The ability to quickly detect a fault, isolate a small section of line, and reconfigure the system to automatically restore service to customers is key to improving service and reliability in DNA systems. Using information from the various intelligent electronic devices (IEDs) in the distribution system, the DNA system is able to reconfigure the distribution system to minimize the number of customers impacted, while preserving protection coordination and mitigating equipment overload. The distributed or centralized intelligence allows the system to detect and reconfigure in the presence of multiple permanent faults, keeping the lights on for most customers even during significant storms or severe weather. High-speed restoration is also available for critical loads, such as hospitals or technology parks.
Volt/VAR control is one of the most cost-effective ways to improve distribution efficiency and reduce system losses. SEL DNA systems can provide adaptive volt/VAR control that maintains efficient operation of the distribution system even after reconfiguration. Additionally, conservation voltage reduction schemes can be implemented to reduce consumption during periods of peak demand. The DNA system works in conjunction with both voltage regulators and capacitor bank controls to flatten voltage profiles and/or improve power factor.
Reduce repair crew windshield time by using fault location information provided by a DNA system. Information gathered from IEDs on the feeder is used for locating faults. Strategically locating faulted circuit indicators (FCIs) can further help pinpoint the fault. Wireless FCIs can be incorporated to provide centralized fault location information, or standalone FCIs located on the lines can help visually guide repair crews to the fault. SEL offers both overhead and underground FCIs to aid in improving reliability.
SEL DNA systems that use SEL-451 Protection, Automation, and Bay Control System; SEL-751 Feeder Protection Relays; SEL-651R Advanced Recloser Controls; or SEL-651RA Recloser Controls include SEL’s patented high-impedance fault detection technology called Arc Sense technology (AST). Protect your customers from the dangers of downed conductors and minimize outage times with AST. Poorly conductive surfaces can cause fault current levels that are too low to be detected by conventional overcurrent protection elements. With AST, detect more high-impedance faults and downed conductors to improve safety and restore power quickly.
Increasingly, distributed generation is being added onto distribution circuits. DNA systems can incorporate both the intertie protection and reliable anti-islanding of the distributed generation to ensure that it is disconnected from the feeder if there is a loss of system supply, which complies with the IEEE 1547.1 standard for interconnection of distributed generation. Ensuring that all distributed generation is tripped off is critical to maintain lineman safety, avoid out-of-synch reclosing, and reduce equipment damage due to unregulated voltage.
To ensure secure system access, SEL DNA systems use centralized authentication via Lightweight Directory Access Protocol (LDAP), provide audit trails via access logs, and can include encryption on wired or wireless communication links, aiding in NERC CIP compliance. The Distribution Automation Controller (DAC) automatically generates event reports that can be downloaded from the DAC web interface or emailed for simplified analysis and historical performance analysis. SEL DNA systems can also provide miscoordination detection and correction based on analyzing information seen by field devices. Use engineering access to review and improve device settings based on postevent analysis. Send DNA system information to existing EMS systems to simplify integration for operators. Greatly improve system understanding by adding high-resolution synchrophasor data to detect oscillations or transients that SCADA misses.
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