A introdução da norma IEC 61850 em sistemas elétricos de potência e industriais possibilita a troca de informações entre relés via rede Ethernet. Novas capacidades surgem visando a redução de cabos convencionais e o tempo de comissionamento em subestações e possibilitando a utilização de esquemas de controle e proteção mais elaborados e adaptados para diversas aplicações. Através da utilização das funções de proteção com troca de informações através de mensagens GOOSE (Generic Object Oriented Substation Event) entre os IEDs (Intelligent Electronic Devices), redes Ethernet ganham papel importante nos esquemas de proteção e controle e torna-se necessário que a mesma tenha alta disponibilidade e confiabilidade tornando o seu monitoramento obrigatório em subestações. Alguns recursos como portas Ethernet dual nos IEDs e redes de switches em anel garantem a redundância de comunicação, aumentando a disponibilidade do sistema de automação e proteção da subestação, assim como IEDs com monitoramento dos links de comunicação nas portas Ethernet. Ao utilizar-se a norma IEC 61850 para projetos de automação de subestações, faz-se necessário revisar as lógicas e esquemas de proteção contemplando o monitoramento da comunicação pelo IED.
Este artigo relata uma visão das principais lógicas e esquemas de proteção em uma SE.
Este artigo visa contextualizar o cenário nacional de aplicação de cargas em transformadores de potência. Aborda os principais aspectos da norma NBR 5416/1997, da Resolução ANEEL 191 dez/2005, do Procedimento de Rede do ONS Submódulo 2.3. Também será apresentado o campo de aplicação e descrito os pré-requisitos necessários para a utilização de monitor térmico digital com confiabilidade e segurança. É ressaltada a necessidade da criação de uma base de dados para a parametrização dos monitores térmicos digitais, assim como os recursos necessários na especificação do mesmo, para atender plenamente o controle da carga aplicada e a importância do sistema de resfriamento com partida automática.
O avanço da aplicação da norma IEC 61850 nos projetos de subestações, a presença de redes Ethernet na área de energia elétrica cresceu exponencialmente na última década. Contudo em termos de segurança cibernética, os projetos de subestações normalmente empregam apenas medidas perimetrais como roteadores e firewalls. Tais equipamentos não garantem totalmente a segurança da rede uma vez que estes podem ser configurados erroneamente e apresentam pouca, quando nenhuma, eficácia para detectar e impedir invasões originadas internamente. Um controle rigoroso de controle de acesso é necessário, porém tal abordagem requer uma metodologia dinâmica e integrada a um sistema de autenticação centralizado.
A proteção de filtros harmônicos é uma das áreas de proteção de sistemas elétricos com parcos recursos literários, inclusive em termos de padronização internacional. Este artigo apresenta uma discussão sobre a proteção de filtros harmônicos; um filtro de dupla sintonia, 3° e 5° harmônicos, é usado como exemplo. Os filtros de harmônicos são constituídos de capacitores, reatores e resistores, necessitando de funções de proteção específicas para cada elemento. As aplicações atuais de proteção não consideram este fato e não fornecem uma proteção abrangente e confiável. O artigo apresenta uma proposta de proteção, a qual tem como base a experiência de Furnas na operação de filtros harmônicos.
O artigo descreve um elemento diferencial de sequência-negativa que melhora a sensibilidade para faltas internas entre espiras sob condições de carga pesada com supervisão na detecção de faltas externas, adicionando segurança a este elemento durante faltas externas com saturação do TC. O artigo também descreve um elemento direcional para a detecção de faltas restritas a terra, próximas ao neutro. Ao final, faltas são aplicadas ao modelo criado no RTDS para a verificação da sensibilidade e confiabilidade do diferencial de sequência-negativa e do elemento direcional de faltas restritas a terra ao transformador
Em uma refinaria de petróleo trabalha-se com grandes quantidades de produtos inflamáveis a altas pressões e temperatura, e mantê-los sob controle é uma tarefa árdua. Manter o sistema elétrico durante um distúrbio é fundamental, não só para garantir a continuidade operacional, mas também reduzir o impacto ambiental e preservar a segurança das instalações e das pessoas que nelas trabalham. É neste contexto que se faz necessário um sistema de descarte de cargas (load shedding system) para garantir a estabilidade do sistema elétrico e com isso minimizar os impactos do distúrbio no processo produtivo.
Este artigo examina os benefícios do uso da tecnologia de redes definidas por software (sigla em inglês, SDN) para facilmente interconectar e gerenciar o tráfego em redes Ethernet TO que se comunicam usando a tecnologia IEC 61850. Um estudo de caso da Usina de Itaipu, na América do Sul, uma das maiores instalações hidrelétricas do mundo, é usado para ilustrar esses benefícios.
Este artigo técnico descreve o projeto e o comissionamento de um esquema de chaveamento controlado para energizar e desenergizar um transformador de 220/18 kV - 485 MVA. Ele destaca o uso de oscilografias de alta resolução para complementar os testes do disjuntor para obter uma crítica configuração do tempo de antecipação para o esquema. Os resultados mostram que ao usar um dispositivo de chaveamento controlado e ajustes finos para o tempo de antecipação do disjuntor, correntes de inrush superiores a 3 pu foram reduzidas para menos de 0,2 pu.
A confiança nos relés de proteção digitais tem aumentando constantemente nas últimas quatro décadas desde sua invenção. Como a vida útil desses dispositivos ultrapassa várias décadas, as questões sobre quando e como substituir estrategicamente esses relés estão aumentando. Este artigo técnico define termos associados à confiabilidade de relés de proteção, fornece dados de confiabilidade do ciclo de vida observado em campo e sugere estratégias de substituição.
Este artigo apresenta detalhes da implementação de um esquema de proteção de gerador com características adaptadas à curva de capabilidade da máquina. O esquema proposto fornece uma aprimorada proteção de gerador e simplifica a coordenação dos elementos do esquema com o limite de subexcitação do gerador.
Este artigo discute a proteção de transformadores com terminais a dois dijuntores. Abrange os conflitos que frequentemente devem ser analisados entre segurança e sensibilidade da proteção para este tipo de aplicação. O artigo descreve métodos para elaborar esquemas de proteção de transformadores e apresenta diretrizes para selecionar relações de TC´s e ajustar elementos diferenciais com e sem restrição.
Este artigo demonstra o uso das curvas de capacidade de faltas passantes do transformador fornecidas pela norma IEEE C57.109 para avaliar o dano por faltas passantes causado por várias sequências de religamento em um transformador da distribuição usado como exemplo.
Este artigo técnico descreve as características,confiabilidade e segurança de um sistema de sensores de proteção de alta velocidade sem fio e sua capacidade para um esquema de disparo rápido de barras. Detalha como a Cooperativa Elétrica Blue Ridge usou essa tecnologia em uma subestação para reduzir custos, evitando a substituição de equipamentos e mudanças de fiação de campo, enquanto melhorou a segurança de trabalhadores.
Este artigo técnico compartilha uma experiência em campo numa concessionária de energia elétrica indiana utilizando proteção em ultra-alta-velocidade e localização de faltas por ondas viajantes. O artigo discute uma instalação piloto de relés de proteção de linhas de transmissão com tais capacidades e apresenta o desempenho tanto da função de proteção como daquela de localização de faltas para casos de faltas internas na linha de transmissão deste projeto piloto.
A proteção terra estator 100% típica para uma única unidade geradora aterrada por alta impedância envolve o uso de um elemento de sobretensão de neutro em conjunto com um esquema de terceiro harmônico ou esquema de injeção.
Este artigo técnico discute considerações sobre a aplicação de relés de proteção de linhas de transmissão com recursos de comunicação e utilizando cinco zonas para a função de distância. Esta discussão aborda como os modernos relés digitais podem beneficiar o sistema de potência quando apropriadamente aplicado em esquemas de teleproteção e como retaguarda num esquema convencional de distância escalonado.
Neste artigo, discutiremos um esquema de distância quadrilateral adaptativo que pode detectar resistência de falta maior do que na implementação anterior. Além disso, o artigo discute as considerações da aplicação dos elementos de distância quadrilaterais.
Este artigo analisa o que pode ser obtido com um dispositivo de chaveamento controlado moderno em termos de melhoria da qualidade de energia, protegendo tanto os equipamentos de potência quanto o disjuntor, e melhorando a confiabilidade dos relés de proteção.
Este artigo fornece uma explicação básica dos princípios da proteção no domínio do tempo e da localização da faltas por ondas viajantes, além de discutir os benefícios para o sistema elétrico de potência obtidos com uma proteção de ultra-alta velocidade, localização precisa e rápida de faltas e a utilização de taxas de amostragem em megahertz. Ele também discute problemas reais solucionados pela aplicação das tecnologias de domínio do tempo.
Este artigo fornece uma análise da interrupção de energia induzida por ataque cibernético na Ucrânia de 23 de dezembro de 2015 e apresenta uma discussão sobre os métodos de mitigação e recomendações que teriam protegido o sistema de controle da Ucrânia.
Este artigo técnico mostra a evolução da proteção de motores de indução com modelos térmico mais preciso, detecção de barras rompidas no rotor e detecção de arco elétrico incorporada.
artigo apresenta a filosofia dos relés de proteção adotada para proteger os
filtros de harmônicos em uma instalação de 600 kV bipolares, associada com
uma linha de transmissão em corrente contínua de 2400 km no Brasil.
Este artigo descreve a operação de um sistema de controle de uma usina de geração FV frente aos desafios associados à interligação destas instalações ao sistema de potência.
Este artigo discute o uso de redes definidas por software (SDN: “Software-Defined Network”), uma nova arquitetura na tecnologia de redes, visando preencher a lacuna entre a interoperabilidade e os requisitos de transporte das comunicações de alta confiabilidade para o sistema de potência.
Este artigo fornece recomendações para testes dos relés da SEL e diretrizes para o desenvolvimento de um programa de testes em conformidade com a norma NERC PRC-005-2.
Este artigo fornece uma visão geral das tecnologias e sistemas baseados em tempo normalmente utilizados para fornecer tempo preciso, discute as vulnerabilidades do sistema de tempo baseado em GPS e explica como projetar sistemas de distribuição de tempo resilientes para aplicações do sistema de potência visando atenuar estas vulnerabilidades.
Os relatórios de evento continuam a ser um recurso inestimável dos relés baseados em microprocessador. A análise de alguns eventos é relativamente simples e direta, mas outros exigem experiência e conhecimento considerável do sistema de potência e do sistema de relés de proteção para encontrar a causa raiz. Esta sessão fornece diversos exemplos de eventos avançados do mundo real, tempo para avaliação dos mesmos, e soluções.
Este artigo fornece um tutorial sobre a localização de faltas baseada em onda viajante ("traveling wave" – TW) e descreve um algoritmo de localização de faltas baseado em TW que usa medições com sincronização de tempo das correntes das TWs nos terminais da linha para determinar a localização da falta.
Este artigo discute vários aspectos essenciais do projeto elétrico, projeto da rede de comunicação, proteção e controle, além dos testes e comissionamento de uma subestação baseada no IEC 61850.
artigo descreve os benefícios da aplicação da tecnologia multifuncional nos
sistemas de automação de controle dos canais de água. De forma similar a uma
aplicação de distribuição de energia, protocolos de comunicação, lógicas
padronizadas e dispositivos robustos são usados para monitorar e controlar o
fluxo de água, gerenciando ao mesmo tempo a energia necessária para o processo.
Este artigo explora um método de controle de tensão com o objetivo de conservação de energia. A abordagem tradicional da redução da tensão de conservação nem sempre é a abordagem adequada para todos os tipos de cargas de alimentadores; algumas cargas operam de forma mais eficiente em uma tensão mais alta.
Primeiro, este artigo apresenta os desafios do sistema de potência existente e os requisitos para o ECS. Em seguida, são descritos o projeto da solução do ECS e a rede de comunicação.
Este artigo discute os aspectos de implementação e aplicação da localização de faltas através de ondas viajantes em um relé de proteção. Limitações de desempenho são discutidas, bem como os requisitos do sistema e considerações da instalação prática.
objetivo deste artigo não é rever os princípios de proteção dos geradores, pois
isso já foi amplamente efetuado em outros trabalhos, mas sim relembrar os
princípios básicos de física e engenharia que estão por trás da interação entre
o AVR de um gerador síncrono e seus limitadores associados, além de algumas
funções de proteção de geradores.
Os relatórios de evento têm sido um recurso inestimável dos relés microprocessados desde a introdução inicial da tecnologia. Os dias de causa raiz desconhecida para interrupções de operação prolongadas ou resultados de testes inexplicáveis estão amplamente superados devido à esta ferramenta e à capacidade de utilização da mesma por engenheiros e técnicos. É necessário praticar para se tornar proficiente na análise de relatórios de evento. Esta sessão fornece exemplos de eventos do mundo real, tempo para avaliação dos mesmos, e soluções.
Este artigo analisa os efeitos da saturação em vários desses elementos e fornece diretrizes de aplicação que eliminam ou minimizam o risco de saturação do TC.
Este artigo discute o sistema SCADA existente e o sistema de monitoramento de uma área ampla (“wide-area monitoring system” – WAMS) recentemente instalado no Centro de Despacho de Carga da Região Norte (“Northern Regional Load Despatch Centre” – NRLDC) da “Power Grid Corporation of India Limited” (PGCIL).
Considerando a competitividade do mercado de energia elétrica, a prevenção de faltas e defeitos nos equipamentos primários das subestações é considerada um fator diferencial significativo para a qualidade da energia elétrica fornecida pelas concessionárias. A redução do número de faltas e defeitos que causam interrupções no suprimento de energia elétrica contribui enormemente para a melhoria dos índices de desempenho dos serviços prestados. Para atingir este objetivo, é necessária a adoção de práticas de manutenção mais eficientes e inteligentes, além da aplicação adequada dos recursos materiais, humanos e financeiros.
Neste artigo, apresentamos um exemplo de um esquema de rejeição de geração nos sistemas de transmissão de 400 kV, onde a CFE está avaliando o uso da diferença angular através das medições fasoriais sincronizadas para melhorar a confiabilidade dos esquemas de rejeição de geração existentes.
Este artigo discute os conceitos fundamentais dos sistemas de rádio, considerando-os em termos dos requisitos de controle e proteção para os modernos sistemas de potência.
Este artigo aborda outro método para aumentar a confiabilidade dos computadores de subestações - projetá-los para usar memória com código de correção de erros (ECC: “Error-Correcting Code”). O uso da memória ECC minimiza a classe de erros de memória específicos de inversão de bits (“single bit flips”). Quase todos os computadores de classe de servidor usam memória ECC, mas muito poucos computadores de subestação usam memória ECC.
Este artigo apresenta um teste efetuado
recentemente pela área de distribuição de uma concessionária de energia
elétrica para substituição das Unidades Terminais Remotas (UTRs) das chaves de
seccionamento do tipo "padmounted" por controladores de automação programáveis expansíveis, baseados no
protocolo IEC 61850.
artigo descreve a solução adotada pela Comisión Federal de Electricidad (CFE),
que instalou com sucesso um sistema de indicação de faltas com comunicação sem
fio a um leitor remoto portátil em seu sistema de distribuição subterrâneo.
Este artigo descreve o projeto de modernização e energização da SE Guarujá 2, uma subestação integrada através da suite de protocolos IEC 61850.
Devido aos casos já registrados de disjuntores fechando com retardos, uma segura e confiável solução custo-benefício foi desenvolvida para evitar problemas futuros.
Este artigo analisa o conceito e aplicação de crosspoint switches de alta velocidade para implementação do esquema de rejeição de cargas numa instalação industrial.
Universidade de Stanford empenhou-se na execução do projeto de modernização dos
sistemas de proteção e controle de sua Subestação Palou.
relés de proteção multifunção possuem recursos abrangentes de monitoração que
podem detectar os estados de alerta e de emergência, minimizar os distúrbios no
sistema e evitar o colapso do mesmo.
Este artigo analisa várias técnicas usadas para detectar faltas provenientes de fontes delta. O artigo faz uma revisão da natureza das contribuições da corrente de falta e das características a tensão das fontes delta não aterradas, usando a análise das componentes de seqüência. O artigo também discute o possível impacto dos sistemas de controle do gerador distribuído e a proteção da interconexão.
Os transformadores de corrente utilizados nas linhas de transmissão são especificados para evitar saturação durante a porção assimétrica da máxima corrente de falta. A saturação é evitada através da seleção da tensão nominal ANSI maior do que a tensão na carga para o valor máximo de falta, com o fator (1 + X/R) aplicado. Isto é possível nas aplicações de proteção de linhas, uma vez que as elevadas correntes de carga resultam no uso de TCs com alta relação e as correntes de falta são normalmente limitadas de três a cinco, e raramente ultrapassam dez, vezes a corrente primária nominal do TC.
Este artigo avalia a confiabilidade das topologias Ethernet de conexão de subestações para a conexão de dispositivos.
Este artigo descreve duas soluções simples com relés, as quais dão a segurança necessária ao “sympathetic trip”, e mantêm a sensibilidade de detecção de faltas desejada. Também apresenta exemplos do sistema, que ilustram como inserir as impedâncias das cargas nos diagramas de componentes simétricas.
Este artigo foi desenvolvido como um estudo de caso do projeto e instalação de uma casa de controle de uma subestação.
Este artigo fornece uma introdução à utilização de rede Ethernet nas subestações de energia elétrica. Além dos termos e conceitos básicos das redes Ethernet, ele trata de assuntos específicos relativos às redes Ethernet em subestações.
Neste artigo, identificamos as ameaças a controladores de subestações e sistemas SCADA e discutimos mecanismos de mitigação para reduzir a vulnerabilidade às invasões eletrônicas maliciosas.
Este artigo discute o processo de fechamento e interrupção dos contatos metálicos.
O artigo discute a modelagem dos cabos através de componentes simétricas e analisa a performance do elemento direcional de seqüência-negativa durante condições de faltas nos cabos.
Este artigo revisa as tecnologias existentes sobre bancos de capacitores, discute as vantagens e desvantagens das diferentes tecnologias de capacitores e detalha as razões do por quê a Pacific Gas and Electric Co. (PG&E) está implementando a tecnologia de capacitores sem fusíveis em todos os novos projetos nos sistemas de 115 e 230 kV.
Este artigo discute uma nova abordagem para encontrar controle, monitoramento e proteção de linha de alta velocidade, utilizando comunicação lógica digital relé-a-relé microprocessado.
Nós quantificamos a probabilidade de operações errôneas (sobredisparo, desligamento retardado), cobertura da resistência da falta, tempos de operação e complexidade dos diversos esquemas de proteção populares. Propomos um novo esquema, que proporciona operação mais rápida, melhor cobertura da resistência da falta e minimiza os riscos das operações irregulares.
O Relé SEL-321 contém um elemento direcional inovador que usa as grandezas de seqüência-negativa tradicionais de um modo um pouco diferente do que é usado pelos elementos direcionais de seqüência-negativa tradicionais. Este artigo descreve e fornece um método para testar esse novo elemento direcional.
Este artigo apresenta a resposta dos relés microprocessados para formas de onda tais como a distorção do terceiro harmônico na corrente do neutro de distribuição, formas de onda de corrente de retificador de seis pulsos com ressonância, corrente de energização magnetizante do transformador e falsa corrente diferencial em TC’s de barramento em anel, causada por remanência desigual.
O artigo conclui mostrando várias aplicações de proteção de linhas de transmissão para os relés microprocessados.
Os relés microprocessados na distribuição proporcionam melhorias técnicas e economias no custo sob vários aspectos.
Este artigo é um tutorial sobre a análise de circuitos trifásicos de um circuito de linha de transmissão e é de um padrão que pode facilmente ser implementado num computador, usando um programa matemático como Mathcad.
Este artigo mais adiante define a eficiência do autoteste em relés digitais.
Este artigo examina o critério baseado em Z = V/I e expõe as degradações devidas ao fluxo de potência e à resistência de falta.
A maioria dos relés digitais de distribuição proporciona a proteção tradicional para sobrecorrente de fase e terra, funções de religamento e informação limitada sobre medição e eventos. Neste artigo, as características adicionais de relés digitais de istribuição mais avançados serão discutidas.
This paper describes the implementation of a circulating current scheme that uses IEC 61850 GOOSE messages to provide automatic voltage regulation for up to four paralleled power transformers.
This paper explains how the X/R ratio and the relay operating time affect the asymmetrical current breaker rating. The paper proposes how to derate a breaker for the relay operating time that is shorter than the standard reference relay time of 0.5 cycle. The paper calculates the “rating loss” due to fast tripping and concludes that applying customary margins when selecting breakers may be sufficient to mitigate the effect of ultra-high-speed relays without the need to replace breakers.
This paper documents how PPL Electric Utilities improved high-impedance fault (HIF) detection on their distribution system by adding an HIF detection algorithm and updating metering technology while still using their existing protective relaying. The paper documents live downed conductor detection testing and the associated findings along with lessons learned from the initial pilot and subsequent enhancements to the system, including adding HIF tripping logic.
Avista Utilities has been in the process of upgrading a set of 8.8 MVA, 4 kV, 48-pole, 60 Hz generators at one of their hydroelectric facilities. The authors took this unique opportunity to perform destructive testing on one of these generators prior to its scheduled upgrade. This paper describes the planning and execution components of this destructive testing and also discusses the lessons learned throughout the entire process.
Several transmission protection misoperations have occurred because of the operation of pilot protection schemes during transmission line switching. In this paper, we discuss many solutions implemented by various utilities and compare the solutions against real-world events.
Power systems are technological marvels. However, as protection has become faster, automation more prevalent, and communications wide-spread, protection systems have become more complex. A. R. van C. Warrington wrote, "In spite of good intentions ... there is a tendency to extend the operation of relay schemes by adding additional features until complexity results and then it becomes necessary to re-design." Is there an opportunity to reset the complexity curve and still achieve high-speed, sensitive, selective, and simple protection systems that provide automation, system visibility, and cybersecurity? We believe the answer is YES!
This paper reviews the merits of controlling autoreclosing based on the location of the fault. Special attention is given to hybrid lines comprising underground cable sections and overhead line sections. The paper explains how the traveling-wave technology allows precise fault locating on these lines and how to use the fault location for autoreclosing for faults on overhead sections and blocking autoreclosing for faults on cable sections.
This paper revisits different grounding practices in distribution power systems. It discusses how system grounding and load connection impact the sensitivity of detecting higher-impedance ground faults. The paper discusses possible ways of improving the ground fault detection sensitivity for different systems. The paper illustrates that no single economical technology or practice available today can guarantee 100 percent reliable high-impedance ground fault detection. To provide a perspective with respect to ground faults versus fire ignitions, the paper reviews several staged downed conductor tests and summarizes key research findings in released energy of arcing faults and fire ignition.
This paper shows why correct CT selection is important for the reliable operation of generator differential protection and, for instances where the CTs cannot be matched properly, provides insight into different mitigation strategies. The paper examines a case from a user who encountered a generator relay misoperation during black-start conditions and discusses how the problem was solved using the strategies presented in the paper.
This paper discusses a pilot installation experience of using ultra-high-speed (UHS) protection and traveling-wave fault locating on a hybrid line at a power utility in India. The paper presents details about the hybrid line pilot installation, commissioning of the UHS relays for protection and fault locating, and overall performance of the UHS relays for faults recorded on the pilot system.
This paper offers practical corrective action plans (CAPs) that can provide PRC-026 compliance in nearly all cases without replacing the relays or preventing trips for true out-of-step power swings. The paper discusses various types of power swing blocking (PSB) and out-of-step tripping (OST) schemes and other features available in multifunction line relays that can help with compliance. Many of the CAPs presented are not the solutions you expect.
This paper provides insight into the similarities and differences in the IEEE and IEC CT sizing requirements for generator and transformer differential applications and presents easy-to-use CT requirements and setting guidance for secure protective relay application. An application example is included.
This paper describes an arc-flash event that occurred at the first 10 MW grid-tied energy storage plant in India. It explains how an installed arc-flash protection application used light sensors in conjunction with ultra-high-speed overcurrent elements to trip quickly. The paper also explains how important the inter-tripping between different voltage levels can be for reducing incident energy and preventing further damage from an arc flash.
This paper describes a new algorithm that uses only single-ended measurements to reliably detect broken conductors and estimate their location by using the charging current of the line. We can use broken-conductor detection to trip the breakers before the conductor touches the ground and creates a shunt fault and block any attempt to reclose the line onto this permanent fault. The proposed algorithm is validated by three field events from 57.1 kV and 220 kV lines and results from EMTP simulations.
This paper discusses a Public Service Company of New Mexico (PNM) project to intersect an existing 345 kV series-compensated line. It also discusses the challenges encountered when protecting overcompensated extra-high-voltage lines and provides a performance comparison of phasor-based and ultra-high-speed protective relays using real-time digital simulation.
Every high-voltage transmission line draws capacitive charging current that a line current differential (87L) relay must compensate for; otherwise, the protection scheme might misoperate. This paper reviews charging current theory, calculations, and compensation methods. It also provides guidelines to help protection engineers determine when charging current compensation is required for an 87L scheme.
This white paper provides a comprehensive review of distribution protection technologies available today for wildfire mitigation. The solutions outlined in this paper focus on enhanced system protection and system hardening, and they are designed to minimize risk in the areas most susceptible to wildfire ignition.
This paper discusses protection scheme design methodology and challenges for shunt reactor applications. The paper discusses the possible improvements to the protection scheme design in consideration of tertiary dry-type reactors using modern relays. In addition, the paper also discusses the overall protection design as applied to the San Diego Gas & Electric (SDG&E) system for reactor bank and related tertiary bus applications.
This paper shares a set of equations for sizing chokes for isolated-parallel power systems. The theory behind each equation is shared, and chokes are sized for an example power system.
This paper explores security weaknesses in the GOOSE protocol and how to mitigate them using managed switches and software-defined networking (SDN).
This paper explores how touchscreen technology has evolved, compares popular touchscreen technologies, and discusses common misconceptions about touchscreen technology for power system applications.
In this paper, the Purdue Model is used to design defense-in-depth cybersecurity methods to implement human-to-machine and machine-to-machine digital communications within an energy control system (ECS) communications network. The ECS communications architecture is divided into multiple appropriate levels with unique requirements and features from the process up through the station and finally to the control center.
Improving how your power system is monitored and controlled can provide operational and maintenance benefits greater than the initial capital investment. This paper examines the financial and non-monetary benefits provided by relay replacement programs.
This paper presents an out-of-phase synchronization (OOPS) protection scheme for detecting faulty generator synchronization and providing high-speed tripping. It demonstrates the performance of the scheme with a real-world event in which a steam turbine generator was synchronized 180 degrees out of phase. The paper also includes a discussion of testing methods for verifying synchronization circuits.
This paper discusses how a centralized user and password management system can enhance the security of secondary system infrastructure. The paper also discusses how this system can enhance substation infrastructure without interrupting operations.
Protective relays provide extensive information that can be retrieved and linked with operational and maintenance topologies, either manually or automatically. This paper details the data that can be retrieved from modern digital protective relays only and how these data can be used to develop an equipment maintenance program that saves time and money.
This paper discusses the basics of control and data planes in a network system. It also compares software-defined networking (SDN) performance with that of traditional Ethernet switches and discusses how SDN optimizes the network in an automation system.
This paper discusses how the implementation of a load-shedding system in a paper mill increased the reliability of the mill while minimizing operating costs and capital losses during unplanned events. The paper further discusses, in detail, the dynamic modeling of a double-extraction steam turbine and the validation of the load-shedding system in a closed-loop environment.
This paper describes how CTs saturate in a simple and intuitive way. The paper describes symmetrical and asymmetrical saturation, remanence, the CT equivalent circuit, the CT excitation graph, ANSI ratings, and how to analyze CT performance using simple equations and tools. It then shows how to detect CT saturation in relay event reports and how relay operation can be compromised during CT saturation.
This paper presents simple rules for the correct selection of transformer differential relay compensation settings and their application to real-world installations.
This paper details an arc-flash mitigation scheme installed on 50 unit substations at a Midwestern pulp and paper mill, which reduced the average arc-flash rating by 90 percent.
This paper provides a comparative analysis of the various communications network topologies and process instrumentation and control devices. The analysis includes the reliability of various systems in terms of unavailability. The cost and complexity of each solution is also evaluated along with the level of expertise required by maintenance teams to detect failures and restore system operation. Performance is evaluated based on the speed of detection and reaction to a power system fault.
This paper explains the principles and illustrates the operation of distance protection including traditional mho and quadrilateral elements, new time-domain incremental quantity distance elements, and future distance elements based on voltage and current traveling waves.
This paper presents a turbine load-sharing and load-shedding system for an islanded liquefied natural gas (LNG) facility in Australia. The system includes three independent and redundant load-shedding schemes: process-based contingency load shedding with predefined load group and load pairs, high-speed underfrequency-based load shedding, and progressive overload shedding with system frequency supervision.
Traveling-wave fault locators are very accurate. To retain the inherently high per-unit fault location accuracy, utilities need a method to convert the per-unit fault location to the tower identifier in order to use their mapping data when dispatching line crews. This paper presents several methods for improving accuracy of tower position information for the purpose of dispatching line crews. These methods use past faults for which the location has been confirmed with high confidence, line taps, and Optical Time-Domain Reflectometry (OTDR) tests for identifying splice locations in the Optical Ground Wire (OPGW) cables.
This paper explains best-known practices and tools available for commissioning arc-flash mitigation systems. Topics discussed include how to select and configure test equipment, interpret device self-test diagnostics, and validate system performance with event reports and time-synchronized devices.
This paper discusses how ground faults affect distance relays that are set to reach through delta-wye transformers.
This paper examines single event upsets (SEUs), their causes, mitigation methods, and most importantly, how engineers can make the protection system more resilient if or when SEUs occur. The paper quantifies how often SEUs are likely to occur and suggests and compares some practical application and control design solutions.
This paper examines the problem of determining a system’s X/R ratio when there are parallel circuits at the fault and no single X/R precisely describes the current. It develops a rigorous method to construct and algebraically solve the differential equation of the fault current, thus providing the accurate transient component. Examples are provided, and the concept of a variable X/R is proposed to consider the actual impact of the transient current.
This paper documents the experience of applying an ultra-high-speed relay that uses incremental quantities and traveling-wave-based protection elements on a 115 kV line. The paper provides extensive event analysis to evaluate the performance, security, sensitivity, and dependability of the relay and presents the lessons learned from the application.
Public Service Company of New Mexico (PNM) selected ultra-high-speed (UHS) line protective relays for their 345 kV lines, in addition to their phasor-based protective relays. In this paper, we discuss the procedures followed during the commissioning, bench, and end-to-end testing of the PNM UHS line protection.
When designing Sampled Values-based (SV-based) substations, engineers must prove that SV-based schemes are as secure and reliable as traditional protection systems. This paper discusses the impact of communications conditions on line protection, provides benchmark test results, and highlights considerations that protection engineers should factor in when implementing SV-based line protection schemes.
This paper provides accounts of undesired operations that have occurred in real recloser installations, reveals the root cause, and offers techniques to mitigate against future failures. The paper categorizes recloser installation misoperations as single-pole tripping, reclosing, and apparent miscoordination issues. The paper recommends commissioning and maintenance practices as well as tips for troubleshooting and repairing recloser systems.
This paper is a tutorial on protection applications of sequence components, focusing on advantages, limitations, and application considerations.
High-frequency traveling-wave technology is entering the power system application mainstream, bringing with it an unprecedented level of highly accurate signal detail. This paper documents and explains some of the more surprising, lesser-known, and strange-looking waveforms captured while monitoring high-voltage transmission lines with megahertz sampling.
This paper demonstrates intelligent electronic device (IED) resiliency to high-altitude electromagnetic pulse (HEMP) events through analysis and test results. It presents substation grounding and wiring practices that are HEMP resilient and also highlights available HEMP standards as they relate to IEDs and substation control houses. This information will help utilities prevent unnecessary mitigation efforts and address the concerns regarding the effects of HEMP on substations and substation IEDs.
This paper examines the application of GOOSE over Ethernet radios and the associated challenges. The paper shares results from a real-world implementation, including results from GOOSE latency tests for protection and control applications.
This paper describes the components of a wireless protection sensor system, its integration with protection devices, and how the fault information can be transmitted from the sensors to such devices at protection speeds. Additionally, this paper discusses how protection devices use this low-latency fault information to securely speed up the operation speed of and improve the selectivity of distribution protection schemes.
This paper explores how operational technology software-defined networking (OT SDN) can deliver benefits for OT networks in determinism, traffic control, and failure recovery by using an application-focused, proactive, and predictable design based on a deny-by-default cybersecurity architecture. This paper then describes an approach to designing and deploying an OT SDN network to incorporate these benefits by focusing on discussing design processes (such as requirement gathering, topology design, and path planning) and engineering considerations (such as automation, validation, and testing).
This paper discusses cryptographic system implementations in operational technology (OT) environments and how protocols such as IPsec, TLS, and DNP3-SA can be mapped onto common distribution communications architectures. It also provides recommendations for OT system owners and manufacturers who wish to implement cryptographic solutions.
As utilities implement packet-based Ethernet transport technology, communications engineers must design pilot channels that still meet strict protection application requirements. This paper describes a deterministic transport solution for critical traffic over packet-based wide-area networks (WANs) that is compatible with both Multiprotocol Label Switching (MPLS) and Carrier Ethernet systems. Live implementation performance data are included.
This paper reports on an experimental investigation that uses wavelength division multiplexing in high-performance power system protection applications. The investigation was performed using the latest generation of carrier-grade optical transport network (OTN) equipment. The paper documents the performance, opportunities, and pitfalls associated with this application and outlines practical strategies for the seamless integration of protection systems with the latest generation of OTN technologies.
This paper discusses many of the common challenges of integrating intelligent electronic devices (IEDs) in an IEC 61850 environment, how to diagnose problems using packet analysis tools and IEC 61850 MMS browsers, and what settings in the IED or Configured IED Description (CID) file need to be adjusted to resolve these challenges.
This paper provides a brief overview of SEL’s Time-Domain Link Technology (TiDL) and IEC 61850 as digital secondary system solutions and assesses the cybersecurity posture of each.
This paper discusses some of the potential causes of open-phase conditions, their impacts on power system operation, the challenges in detecting them, and some novel methods developed to detect them. It discusses the implementation of these methods in microprocessor-based protective relays at several nuclear power generating stations. The paper also presents field results of a successful open-phase detection.
In distribution systems, power utilities are integrating intelligent sensors and advanced communications that go beyond substations and require minimal human interaction. This paper describes many of the technologies and sensor systems that utilities can employ to unlock new distribution applications and enable efficient energy delivery.
This document explains the functionality of the SEL Underground AutoRANGER Fault Indicator (AR-URD). It defines the AR-URD AutoRANGER trip logic, principles of operation, fault indication options, inrush restraint, and testing and reset functions.
This paper discusses the protection and controls for two parallel 400 MVA (+31.3° to –80.1°) phase-shifting transformers at a utility's 230 kV interconnection substation.
This paper describes two categories of impedance-based double-ended fault-locating methods used in transmission systems. The first category includes methods that use local measurements and remote currents. The second category includes methods that use both local and remote currents and voltages. This paper analyzes the accuracy and limitations of known time-synchronized double-ended fault-locating methods and proposes two new methods.
This paper discusses the concept of the "resiliency transformer" and its electrical and physical characteristics. It also discusses aspects related to the design of mobile relay panels, the demonstration and staging of the units, digital secondary protection systems, digital simulations, and commissioning.
This paper presents a case study of a microgrid control system developed, validated, tested, and commissioned for the University of California San Diego. The system provides the ability to detect and decouple during utility disturbances, operate in islanded conditions, and provide resynchronization to the grid.
Telecommunications carriers are ending support for analog leased line services and migrating users to Ethernet-based circuits. This paper presents a solution to the migration challenge based on a technology called virtual synchronous network (VSN) and describes how the utility Consumers Energy validated this solution during trials that used leased Ethernet circuits.
Georgian State Electrosystem implemented a distributed remedial action scheme (RAS) to maintain power system stability in the Republic of Georgia. This RAS was based on customized operating principles devised specifically for Georgia’s power system. This paper describes the genesis of the project, the initial requirements, the reason a distributed architecture was selected, performance indicators, and operation examples.
This paper presents how two-terminal traveling-wave fault-locating (TWFL) methods can be applied to multiterminal and hybrid lines. Laboratory test results and field events from Bonneville Power Administration are discussed to demonstrate the performance of the proposed fault-locating method.
This paper shows how to apply multiple-criteria decision analysis techniques, such as the analytic hierarchy process (AHP), to integrate world-class manufacturing principles into the circuit design process while alleviating the increased complexity of design decisions. Systematic use of AHP in circuit design increases the quality and value of designs while reducing the cost of development.
This paper presents practical solutions for testing traveling wave-based (TW-based) relays and fault locators, including a TW relay test set and relay event playback functionality. Both approaches are capable of performing end-to-end testing when an absolute time reference is used.
Magnetizing inrush creates a spurious operating current in 87T protection. Early 87T relays used harmonics for security during inrush. Today, we can design algorithms that distinguish directly between inrush and fault currents. By using the new algorithms, we improve the sensitivity and speed of 87T protection and maintain security for transformers with cores built from improved steels.
This paper compares the performance of different third-harmonic schemes and shows how these schemes can be applied to provide secure and sensitive stator winding coverage. It also provides additional guidance regarding learning algorithms and coordination with injection schemes.
This paper describes the authors’ experience in designing, installing, and testing microgrid control systems.
This paper discusses the differences between implementing cybersecurity measures in information technology (IT) and operational technology (OT) networks. It introduces software-defined networking (SDN) technology and describes how SDN can be used to build a robust and secure OT network.
This paper reviews three unique CCVT failure events and discusses relay performance during these failures.
This paper discusses an automation system consisting of intelligent electronic devices programmed to exchange information using various protocols to control, protect, and monitor the entire substation.
Keeping in mind the future need of an intelligent power management and control system (PMCS) for smart grid applications, this paper discusses proven design concepts and reliable hardware-in-the-loop testing via a real-time digital simulator. The paper presents various PMCS building blocks, including generation control systems, voltage control systems, an islanding control system, tie-line control, high-speed generation shedding and runback, high-speed load shedding based on contingency and underfrequency, and autosynchronization systems.
This paper describes common failure modes for substation clocks and their recovery mechanisms. It also describes test setups with pass/fail criteria to characterize substation-hardened clocks under conditions of electrical and environmental stress.
This paper presents practical solutions for commissioning testing, including end-to-end testing, of ultra-high-speed relays that use traveling waves and incremental quantities. The paper reviews the relay operating principles and derives adequate testing requirements. It then introduces, explains, and illustrates a testing method that relies on superposition of traveling waves and low-bandwidth signals. The method uses a separate test set to generate sharp current and voltage pulses to represent traveling waves and superimposes them on the low-bandwidth signals provided by a traditional relay test set. The method uses test software to control and synchronize both test sets.
This paper discusses how the SEL-735 Power Quality and Revenue Meter exceeds the nonsinusoidal test requirements for ANSI 0.1 accuracy class compliance. It also illustrates why the SEL-735 is highly qualified for revenue metering applications in today’s challenging power system conditions.
This paper presents a tested generation control system that was designed and implemented to adapt to a generation system with multiple inertias, islands, control modes, and voltage levels that will tolerate system contingencies.
This paper describes new developments in power flow regulating tap-changer control systems for phase-shifting transformers (PSTs), which are also called phase angle regulating (PAR) transformers. This paper discusses recent advancements in the control technology and highlights a particularly challenging application of two parallel PSTs installed on San Diego Gas & Electric's 230 kV transmission system.
This paper describes the design of, and the lessons learned from, a deployment of 300 smart motor control centers for a large oil and gas project in Eurasia. Arc-flash and conventional protection schemes were provided. Manufacturing, testing, and design methods are discussed.
This paper discusses the implementation of a smart grid system for a large dispersed oil field using radios as its communications network. The solution includes high-speed load shedding, online monitoring, event reporting, oscillography, and engineering access. This paper also discusses the process used to design and test the radio technology, including the evaluation of its success metrics, network security, radio path study, and optimization.
This paper describes the design, technology, model development, and overall validation of a hardware-in-the-loop simulation system for the largest oil and gas project in the world. Lessons learned and results from recent testing are shared.
This paper provides an overview of single event upsets (SEUs), including their causes, mitigation methods, and effects on SEL relays. It quantifies the impact that SEUs have on system protection and provides best practices for ensuring reliability.
This paper explores the implementation of PTP on various Ethernet architectures, including enhancements to provide PTP redundancy. In addition, the paper provides reasons to use PTP clocks and recommendations on the types of PTP clocks to select.
This paper introduces a deterministic packet transport method of achieving guaranteed latency for critical traffic being transported over packet-based wide-area networks. The method is standard-agnostic, and it elegantly addresses the challenge of migrating time-division multiplexing-based protection circuits to Ethernet without impacting the performance of the network.
This paper describes an event in which lightning struck a phase conductor of a 345 kV transmission line and discharged current into the phase conductor, but the magnitude of the lightning discharge was insufficient to lead to an insulation breakdown. The paper examines and explains the response of two different line current differential protective relays during such an event.
This paper demonstrates how electromagnetic torque responses can be used to measure the impact of events on a motor in a power system. The paper shows examples of calculating electromagnetic torque using oscillographic event report data obtained from digital motor protection.
This paper highlights the use of symmetrical components for simplifying the analysis of events with non-classic fault waveforms. It first provides a refresher on symmetrical component theory and then analyzes three real-world events using a symmetrical component-based event analysis approach.
This paper describes a single-ended traveling-wave-based fault-locating method that works with currents only and explains how to perform fault locating manually using ultra-high-resolution fault records from any recording device. This paper also presents laboratory test results as well as field cases in which line crews found the actual faults.
This paper compares the performance of different third-harmonic schemes and shows how these schemes can be applied to provide secure and sensitive stator winding coverage.
This paper demonstrates how to analyze faulted transmission lines using phase components (Phase A, Phase B, Phase C) as an alternative to symmetrical components (positive-sequence, negative-sequence, and zero-sequence). The paper explores both steady-state and time-domain applications, with emphasis on generating reliable test signals. Advantages of the phase-domain approach are discussed.
This paper examines various options for obtaining bus protection redundancy. The paper includes an emphasis on examining various methods of applying dual relays in an existing high-impedance bus differential CT circuit.
This paper investigates how, by using the communications and reporting capabilities of modern intelligent electronic devices, a continuously running monitoring system can quickly identify and report signal transmission timing or delivery degradation in a protection system using high-speed peer-to-peer signals.
This paper discusses high-impedance differential protection with respect to applying the scheme with mismatched-ratio CTs. The paper describes methods for accommodating mismatched CTs and reports on high-current laboratory testing of CTs. The testing was performed to assess the risk caused by overvoltage on the end terminal of a higher-ratio CT that was tapped at a lower ratio and connected to a high-impedance differential relay.
This paper reports on an experimental investigation that uses wavelength division multiplexing in high-performance power system protection applications. The investigation was performed using the latest generation of carrier-grade optical transport network (OTN) equipment. The paper documents the performance, opportunities, and pitfalls associated with this application and outlines practical strategies for the seamless integration of protection systems with the latest generation of OTN technologies.
This paper explains how microprocessor-based protective relays are used to provide both control and protection functions for small microgrids. Features described in the paper include automatic islanding, reconnection to the electric power system, dispatch of distributed generation, compliance to IEEE specifications, load shedding, volt/VAR control, and frequency and power control at the point of common coupling.
This paper discusses the design specifications and lessons learned from a project that uses computer virtualization to reduce the computing hardware needs for a modern substation.
This paper discusses the performance comparison of wireless serial and Ethernet communications and innovative wireless network topologies that maximize overall network performance during realistic field conditions. Techniques for simple and inexpensive dual primary data paths are described.
In an IEC 61850 digital substation, merging units connected to instrument transformers stream analog measurements as data packets via an Ethernet network. This paper proposes applying software-defined networking (SDN) path programming and fast failover features to achieve Sampled Values (SV) stream redundancy. The paper also discusses using SDN to manage an IEC 61850 network by logically separating station bus and process bus traffic using SDN path programming.
This paper discusses the preliminary considerations in designing a micro transactive grid that can be used as a platform to share the investment and return of distributed energy resources with a community.
In this paper, the multi-loop fault analysis method is used to determine the sensitivity and coverage provided by various generator internal-fault protection elements for interturn, interbranch, phase-to-phase, and series faults.
This paper shares the initial results and benefits that Blue Ridge Energy Cooperative has achieved by bringing intelligent electronic device oscillography from across their system together in one application.
This paper presents common challenges in distribution protection and demonstrates solutions using the multiple protection elements and custom logic available in modern distribution feeder relays and recloser controls. Solutions are provided to prevent false trips due to inrush, improve protection response times, mitigate conductor slap issues, and improve the performance of noncommunicating loop schemes.
The need for low-cost technology and the sheer number of individually terminated copper conductors in traditional wiring approaches have long fostered a dream of fully digital secondary systems based on fiber-optic communications technology. This paper provides an overview of recent standards that add to the wealth of knowledge describing this technology, explains various options and the relationship among different standards, and identifies some of the future work required in this space.
Numerous digital communications protocols are used in substations to exchange process information traditionally received as low-level analog signals via copper wires from sensors and instrument transformers at the process level. In this paper, characteristics and performance are compared for IEC 61850 GOOSE and Sampled Values messaging, IEC 61158 EtherCAT, IEEE C37.118.2-2011 Synchrophasor Protocol, and Mirrored Bits® communications for their use in copper reduction and distributed communications-assisted control strategies.
This paper discusses how electromagnetic torque can be calculated from oscillographic event report data obtained from digital motor protection. Several example cases are shared.
This paper describes a single-ended traveling-wave-based fault-locating method that works with currents only and explains how to perform fault locating manually using ultra-high-resolution fault records from any recording device. This paper also presents laboratory test results as well as a field case in which the line crew found the actual fault.
This paper describes the challenges associated with protecting pumped storage hydro units. It discusses how digital protective relay schemes provide simpler and more effective protection than traditional electromechanical relay schemes.
This paper presents a new communications-based protection scheme that uses incremental-quantity and traveling wave-based directional elements to make tripping decisions in 4 to 6 milliseconds. It includes a discussion of forward and reverse fault field events that are used to analyze the performance of a permissive overreaching transfer trip scheme.
This paper describes the components of a Sampled Values system and discusses communications network engineering challenges, solutions, and tools available to provide and verify a reliable Ethernet packet transport in the process bus system. Special attention is given to the design of large substations, which need to securely merge the station bus and the process bus into a single, substation-wide network.
This paper explains principles of fault locating based on traveling waves measured only at line terminals for hybrid lines comprising overhead and cable sections. The paper introduces adaptive autoreclosing control logic to allow or cancel reclosing based on the location of the fault. The paper includes examples that explain and illustrate these principles.
This paper presents transformer protection logic for security during magnetizing inrush conditions, especially under transformer ultrasaturation resulting in low levels of even harmonics in the differential current. The protection scheme includes inrush unblocking logic to accelerate tripping for internal short circuits. The paper explains key principles, shares implementation details, and illustrates the concepts with simulation results and field cases.
This paper describes the challenges associated with protecting pumped storage hydro units and how digital protective relay schemes provide simpler and more effective protection than traditional electromechanical relay schemes.
In this paper, we use the multi-loop fault analysis method to determine the sensitivity and coverage provided by various generator internal-fault protection elements for interturn, interbranch, phase-to-phase, and series faults.
This paper discusses the advantages of the time frame capacity factor model for utilities in determining the reliability of a power system with integrated renewable energy sources.
This paper develops an error-checking method for analog-to-digital converters (ADCs) and presents test results for a commercially available ADC which indicate that the error-checking scheme is useful for detecting catastrophic data converter failures.
This paper presents an active power control system for a phase-shifting transformer based on mission priorities. The functional design, technical details, system architecture, and implementations of power controllers are discussed. A case study presents the effectiveness of the proposed controllers.
This paper discusses the installation of a rotor angle measurement system that was commissioned for San Diego Gas & Electric. This installation provides real-time monitoring and recording of generator rotor angle as well as field excitation quantities that can be applied to meet MOD-026 and MOD-027 requirements.
This paper presents a communications-based protection scheme that uses incremental-quantity and traveling-wave-based directional elements to make tripping decisions where coupling capacitor voltage transformers (CCVTs) provide voltage signals to these elements. The paper uses field events captured during forward and reverse faults to analyze the performance of the proposed permissive overreaching transfer trip (POTT) scheme, which achieves operating times on the order of 4 to 6 milliseconds.
This paper describes how Westar Energy implemented a cost-effective distribution automation system that is now providing a very capable and fully automated fault location, isolation, and service restoration and volt/VAR distribution solution.
This paper analyzes event reports that indicated an arcing ground on the neutral end of a large generator. It investigates the limitations of ground protection techniques as well as techniques to overcome these limitations when detecting an arcing ground fault.
This paper discusses the complex challenge of achieving seamless transition between grid-tied and island operation of critical facilities while highlighting fast, reliable, and adaptive protection and control solutions.
This paper presents an efficient and systematic approach for evaluating merging units. It offers engineers help, particularly during merging unit testing, in understanding certain characteristics of a merging unit and in gaining confidence with Sampled Values technology.
This paper describes the Chess Master project, sponsored by the U.S. Department of Energy, which will apply software-defined networking to advance energy sector network cybersecurity.
This paper describes the modeling benefits, challenges, and lessons learned associated with controller hardware-in-the-loop testing. The microgrid system used in this study has a 3 MW battery, 5 MW photovoltaic array, 4 MW diesel generator set, and 3.5 MW combined heat and power generation system.
This paper proposes a fast, secure, zero-setting adaptive algorithm to detect and declare open line conditions using wide-area synchrophasor measurements.
In an effort to move towards smart grid, the Dubai Electricity & Water Authority initiated a long-term contract for the supply, installation, testing, and commissioning of 33 substations with modern automation systems for transmission power substations. This paper discusses the system requirements and various engineering decisions that resulted from lessons learned during the system design stage to ensure that the system is ready for future smart grid requirements. Various analysis tools and testing techniques are described that were used to quantify the performance attributes of the IEC 61850-based system design.
This paper discusses a practical technique for harvesting the maximum power from a large photovoltaic system. The technique tracks the maximum power point from the nonlinear output characteristics of the PV system using an adaptive neuro-fuzzy inference system (ANFIS) to extract the maximum power from the PV system under different conditions.
This paper explains a novel data acquisition method that supports accurate, synchronized, wide-area power flow summation at fixed millisecond intervals.
This paper discusses the fundamentals of how to perform isochronous load sharing in an islanded power system with various makes and sizes of generators (steam and gas turbines). The paper details the decentralized generation control system and also presents other topics crucial for industrial power systems.
By using a defense-in-depth approach, you can provide read-only SCADA data and Syslog messages to corporate or other networks. The layered defense includes adding a perimeter network, read-only HMI and Syslog server, and a one-way data sending mechanism through SDN and unidirectional firewall rules.
This paper discusses the benefits of applying the new SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System to enhance distribution system protection.
This paper examines methods available for fault location and describes the method employed at Fayetteville PWC. It shares the results of Fayetteville PWC's pilot project and provides the information to implement their fault location system on the reader's distribution system.
This paper describes the analysis and resulting investigation that occurred when a CT secondary wire made contact with a transformer bushing, causing an outage at a 138 kV substation.
This paper describes the design and testing of the first stage of a synchronism-check upgrade to the Whakamaru Power Station. The scheme allows simultaneous synchronization of up to four 11 kV generators with up to four 220 kV lines located over one kilometer apart.
This paper examines the dynamic mho expansion for positive-sequence memory polarization during a variety of different faults and changing system conditions.
This paper highlights critical parts of the COMTRADE standard and limitations to replaying event files into a relay. It also provides readers a deeper understanding of COMTRADE files and how replaying system disturbances can yield different responses in the protection elements when compared with the original event.
This paper explains practical design principles to follow for networked protection and control systems. Proven cybersecurity best practices, system architectures, monitoring methods, and defense-in-depth techniques are described.
This paper introduces the acceptance criteria for digital messages and LAN performance between data producers and data consumers that are necessary in order to exchange signals to support distributed mission-critical applications. It also compares the attributes of five popular protocols to provide information necessary for designers to understand the behavior and performance of each protocol.
This paper describes two regional system integrity protection schemes implemented in Turkey to avoid regional blackouts and the propagation of disturbances to neighboring countries.
This paper introduces the concept of using terrestrial private communications networks for the distribution of high-accuracy time and provides methods for mitigating specific GPS vulnerabilities.
This paper explains the technical issues that have been addressed during the past decade of Sampled Values technology development and explains how these issues are resolved with the use of software-defined networking for process local-area network packet switching and fault recovery. It also introduces the correlation between accessible electricity and economic improvements, and it discusses the importance of low installation costs, low lifecycle costs, and high availability and resistance for added or expanded power systems.
This paper analyzes the Sampled Value process bus concepts that have recently been updated by various IEC working groups. The authors are engineers with over a decade of participation in developing the IEC communications standards.
This paper presents actionable information regarding the critical requirements of a fully trusted industrial control system network. It examines the strengths and weaknesses of existing solutions for implementing trust management.
This paper describes a three-terminal line differential protection project designed for a rail company as part of a refurbishment project. The paper explains each of the different technologies used for this project, including line differential over Ethernet, coarse wave division multiplexers, and managed switch configuration. It also provides details of the performance of the system in terms of speed and stability.
This paper summarizes the Ethernet packet performance time definitions in IEC 61850 Edition 1 and the new IEC 61850 Edition 2 time classes, introduces subscribing device features required to confirm proper packet exchange, and illustrates case study examples of in-service local-area network (LAN) failures.
The principles of software-defined networking (SDN) offer significant benefits for operational technology (OT) networking by addressing the limitations of traditional Ethernet. Read more in this white paper.
This paper outlines the benefits of using digital communications between primary substation equipment and the protective relays installed in the control house. The authors discuss two methods used to implement a process bus—a switched network and a point-to-point network—and then introduce a new point-to-point, EtherCAT-based digital substation technology that is robust, simple to use, and secure.
This paper explains how commercial, off-the-shelf protective relays can be used to automatically island microgrids and to then automatically reconnect them to the macrogrid.
Southern California Edison is protecting a new 500 kV mutually coupled transmission line incorporating both overhead and underground sections. This paper discusses the protection challenges faced with this type of arrangement and describes using real-time digital simulation to evaluate the performance of the protection system.
This paper describes an event in which a negative-sequence overcurrent (51Q) element operated for a fault on an adjacent feeder, discusses the impact of voltage unbalance on induction motors, and shares lessons learned to assist engineers to securely set 51Q elements.
This paper discusses the functionality and merits of the high-speed distribution protection implemented for the City of College Station's multiple distribution substations using communications-assisted special protection and control schemes. These schemes were implemented to improve the reliability, selectivity, and availability of the power system.
This paper provides procedures and guidelines for successfully designing and integrating IEC 61850 GOOSE protection schemes while keeping the feasibility of initial commissioning and future expansion and testing in mind.
This paper discusses motoring events and the resulting active and reactive power flows, examines existing reverse power relays used for generator protection, and presents a new algorithm for dependable motoring detection. It also reviews current transformer and voltage transformer accuracy as defined by ANSI IEEE C57.13 and IEC 61869.
This paper introduces new ideas and concepts that complement existing generator protection elements to provide better overall generator protection and monitoring.
In this paper, we use high-resolution event data to discuss switching surges caused by high-speed reclosing on high-voltage lines and their impact on bus differential relays.
This paper describes the design, construction, and commissioning of the microgrid controls for the Duke Energy McAlpine Creek microgrid project and the lessons learned from its implementation.
This paper describes the design of a system that combines event files stored in protective relays and synchrophasor data streamed from phasor measurement units (PMUs) for wide-area system analysis.
This paper compares the intrinsic performance of conventional mho elements and incremental quantity-based distance elements, irrespective of the ways they are implemented. Specifically, it explains that incremental distance elements have superior performance, but they have to be supplemented by conventional mho elements because the incremental elements are only available for a short time.
This paper details a system developed with American Electric Power for monitoring and automatically diagnosing the health of circuit breakers. It presents an overview of real-time data parameters recorded to provide important health diagnostic information that provides insight into the remaining expected life of the breaker. The system uses this information to reduce operations and maintenance costs by eliminating regularly scheduled manual tests and shifting to as-needed maintenance rather than regularly scheduled maintenance.
This paper outlines the three distinct advantages that software-defined networking (SDN) brings to Ethernet-based control systems: dramatically improved packet delivery performance under both normal and fault event conditions, greater cybersecurity without added complexity, and centralized situational awareness with disruptionless change control, enabling seamless scalability.
This paper addresses the use of IEC 61850 network engineering and testing guidelines for performing network acceptance testing and for troubleshooting in-service Ethernet networks. The paper also explains best practices to configure systems to constantly perform self-tests and monitor and record performance statistics.
This paper describes the practical implementation details and operational experience of a new oscillation detection system initially operated at San Diego Gas & Electric. Several examples are provided of successful detection and analysis of events using this system.
This paper discusses improvements to out-of-step protection. These improvements provide adaptive protection based on dynamical system energy balance to more effectively detect potential out-of-step conditions and provide more flexible corrective actions. This method also provides additional robustness by compensating for uncertainties in system parameters.
This paper presents a centralized microgrid control system for effective operation of wind turbines and diesel engines coupled to a flywheel electrical storage component on Saint Paul Island. The wind turbines have sufficient capacity to support the entire island without using the diesel engines, allowing the formation of an islanded power system completely powered by renewables. The control system was tested using hardware-in-the-loop simulation with a simplified electrical model of the Saint Paul system.
This paper discusses what happens when a microgrid control system fails and quantitatively evaluates the impact on microgrid reliability.
This paper describes the logic design, communications infrastructure, and real-time testing of a remedial action scheme implemented in southern Peru.
This paper reviews a number of typical settings found in incremental quantity- and traveling-wave-based protection elements and provides setting guidelines and examples for various applications, including series-compensated lines and lines with tapped loads.
This paper provides insights into how mutual coupling affects ground distance, ground overcurrent, and directional elements in different system configurations; offers practical advice for identifying situations where mutual coupling must be considered; and provides step-by-step guidance for setting ground distance and directional overcurrent elements on transmission lines that are affected by mutual coupling.
This paper focuses on defining and measuring the performance of ultra-high-speed line protective relays, including traveling-wave protection elements.
This paper discusses relay testing concepts, using a line distance relay element as an example.
This white paper describes the early days of programmable logic controllers (PLCs), the introduction of Modbus protocol, and some of the challenges involved today with device interoperability, specifically challenges related to register addressing and data type formatting.
This paper provides a clear set of procedures and equations to follow in optimal current transformer selection for low-voltage motor control centers.
This paper describes a defense-in-depth scheme that applies specifically to the industrial control system realm, with implementation details and an example system.
This paper explains a novel data acquisition method that supports accurate, synchronized, wide-area power flow summation at fixed millisecond intervals.
This paper summarizes the successful addition of a remedial action scheme to an in-service emergency control system in the country of Georgia.
In this paper, we briefly discuss the types of underground cables, their bonding and grounding methods, and the fundamental differences between overhead transmission lines and cable electrical characteristics. Finally, we discuss the application of short-circuit protection for high-voltage ac cables.
This paper discusses how to use event data (voltages, currents, and fault location) from relays at two ends of a transmission line to calculate positive-, negative-, and zero-sequence line impedances. Impedances calculated from real event data can be used to validate relay settings and short-circuit models.
This paper proposes a new principle for generator turn-to-turn fault protection based on the ampere-turn balance between the stator negative-sequence current and the double-frequency component of the field current. The paper describes two protection elements using this principle: a stator-rotor current unbalance element that uses the current magnitudes and a stator-rotor current differential element that uses the current phasors. The paper derives the new methods, discusses their dependability, sensitivity, and security, and illustrates their operation with computer simulations and test results from a physical made-to-scale generator.
This paper provides eight basic guidelines to improve cybersecurity for industrial control systems.
This paper describes the impacts of photovoltaic (PV) installations on power systems and discusses different mitigation methods to address them. The paper proposes a solution to minimize the impacts by using the concept of coordinated control between the substation and the PV generation plant.
This paper analyzes the voltage sags that occurred during a simulated transformer energization study for an offshore platform.
This paper describes the implementation of a power management system for a mature oil field facility and how the system was optimized to use utility generation, its own generation, or both combined for the reliability, stability, and scalability of the facility power system.
This paper demonstrates that errors will exist with a conventional single- or double-ended fault location calculation if the fault occurs during a pole-open condition. Compensated algorithms are presented that achieve accurate fault location under these conditions.
This paper proposes a modular microgrid unit (MMGU) that can work autonomously but is also capable of connecting to other MMGUs to form an expandable microgrid.
This paper describes a new falling conductor detection scheme that trips the affected circuit section in the narrow time window between the moment of the break and the time the conductor hits the ground. The affected circuit section is de-energized while the conductor is still falling, eliminating the risk of an arcing ground fault or energized circuits on the ground.
In this paper, a real-world event and simulations are used to study the impact of dc winding resistance testing on the magnetizing current of a transformer. Solutions are provided to mitigate possible unintended operations.
This paper is an introduction to the deployment of a network intrusion detection system for industrial control systems.
This paper discusses protection system designs for three single-phase-and-spare transformer banks. Ways to improve sensitivity and make it possible to precisely indicate the fault location in the bank are illustrated with examples. The paper also discusses how to design the system to easily reconfigure the differential zones for any spare substitution configuration.
This paper discusses the design and implementation of a distribution automation system developed to detect electric faults using fault indicators and automatically reconfigure the distribution system topology to isolate faulted sections and restore service to the de-energized loads.
Two drastically different types of differential relays, one with a single set of very high-impedance inputs and another with multiple sets of low-impedance inputs, are available for bus differential protection. This paper discusses for each type of relay the concepts used, the pros and cons, and the importance that current transformer selection plays in applications.
This paper discusses improving the security and dependability of line current differential protection schemes on series-compensated transmission lines prone to current inversion.
This paper discusses the installation and commissioning of a generator rotor angle and field quantities measurement system at a 740 MVA combined cycle plant. The paper discusses the lessons learned and possible applications using these measurements.
This paper describes the effect geomagnetically induced currents have on CTs and the resulting impact on protection security and dependability. The paper supports its claims with simulated as well as experimental results.
This paper analyzes and explains why the compensator phase distance elements operated for a utility that experienced a phase cross-connect condition when personnel inadvertently crossed two phases during line switch installation. This paper also discusses the theory of operation of compensator phase distance relays and methods for making elements secure in similar phase cross-connect conditions.
This paper describes and evaluates several commonly applied line protection schemes using analysis tools like fault trees, power system studies, and event analysis. The paper compares the protection schemes in terms of speed, sensitivity, security, dependability, and selectivity.
This paper explains modern nanosecond precision time technologies and new applications they enable.
Ultra-high-speed line protection is becoming a reality today, giving the industry a way to trip line faults in a few milliseconds. One relay described in this paper that uses time-domain principles incorporates incremental-quantity (TD32) and traveling-wave (TW32) directional elements in a communications-assisted tripping scheme, incremental-quantity distance element (TD21), and traveling-wave differential element (TW87). This paper introduces these time-domain line protection elements, shares key details of their implementation in hardware, and illustrates their operation using real-world faults and digital simulations. By comparing the performance of the time-domain line protection elements with the traditional phasor-based elements of the in-service relays that captured the fault records, we demonstrate the performance of the time-domain line
This paper describes the protection challenges and solutions associated with the Penonomé wind power plant in Panama. The paper discusses protection coordination requirements and results, provides recommendations for future enhancements of the protection system, and concludes with a description of an actual event involving two cross-country faults in a 34.5 kV system.
This paper describes the post-fault analysis following a three-phase intercircuit fault on parallel 138 kV transmission lines. Fault study data associated with single fault conditions on each line are compared with time-synchronized disturbance data from protective relays.
This paper details the threats that SCADA and industrial control systems face, how to detect and counter those threats, and how to apply countermeasures, new technologies, and safe practices to these systems.
This paper describes the communications requirements for various protection and control applications, and it discusses the advantages and disadvantages of communications technologies. The paper also describes how network topologies can improve security and dependability, and it discusses cybersecurity practices that are suitable for securing protection communications links.
This paper provides an overview of winding insulation failure modes related to ground faults and discusses all common ground fault protection schemes in detail. The paper contrasts the following aspects of these schemes: sensitivity, speed, security, availability, complexity, and setting considerations.
This paper discusses the implementation of a fast motor bus transfer scheme using existing protective relays. The scheme is designed to respond to local and remote (upstream) events in the substation. This makes possible an attempt to initiate a fast transfer for events that are remote to the motor bus. On a failure to achieve a fast transfer, the scheme resorts to an in-phase transfer and, if that fails, finally a residual transfer. Real-time dynamic modeling was performed to simulate motor bus decay and reacceleration. This paper provides the results of the simulations and the response of the transfer scheme.
This paper provides explanation and comparison of methods of fault identification, i