Protecting Uruguay’s 500 kV System

Challenge

Winter in Uruguay brings colder temperatures and power supply challenges as the drier winter season impacts hydroelectric power generation. To meet the higher winter peak demand, La Administración Nacional de Usinas y Trasmisiones Eléctricas (UTE) has increasingly relied on power imported from Argentina and Brazil via an extra-high-voltage network of 500 kV lines. Because building additional power capacity to meet seasonal demand is expensive, UTE must operate existing equipment close to the operating limits at high utilization levels. Such highly stressed power systems are more prone to instability resulting from faults, which could lead to a blackout of the entire nation.

UTE decided to modernize their power system to help mitigate blackouts. The new solution needed to have fast operating speeds, reliability, and system expandability to allow UTE to systematically shed loads and continue supplying power to large metropolitan areas.

Solution

UTE collaborated with SEL to design a unique remedial action scheme (RAS), the first of its kind in Latin America, to trip loads in subcycle times and keep the power system from getting overloaded, hence avoiding any cascading outages.

Most notably, after load is shed, the RAS solution monitors the system voltage and reactive power flow and ensures that the power factor, voltage, and reactive power compensations are met. Monitoring these compensation factors reduces transmission losses and improves power quality. However, most other RASs do not monitor compensation factors.

SEL and UTE also installed phasor measurement units (PMUs) that can measure synchrophasor data throughout the Uruguayan power grid, providing more detailed analysis to help UTE optimize system performance.

Results

With the RAS in place, UTE is now able to reliably shed loads in the winter and maintain the power supply to key cities, such as the capital city of Montevideo. UTE predicts that the impact of having dependable power will not only affect individuals and their families, but also their enterprises, companies, and society as a whole. With the RAS complete, UTE plans to incorporate their new schemes to support network growth and to maintain and improve the quality of the service they provide.

Customer Profile

Customer: La Administración Nacional de Usinas y Trasmisiones Eléctricas (UTE)

Location: Uruguay

Industry: Utility

Application: Transmission Protection—RAS