Grid Mod: Transmission tool automation will improve reliability and efficiency

The electrical grid is a modern marvel made possible in part by system operators who constantly monitor and adjust the transmission system. They make sure that no facilities are overloaded and the grid is operating efficiently and reliably. It’s like driving a car safely – not going too fast around turns or speeding into a traffic jam – while being mindful of the surroundings. Conditions are always changing, including weather like rain, ice or snow. The driver has to continually monitor the road and traffic, and may need to adjust speed to keep moving safely. Similarly, when an unexpected event occurs that disrupts the delivery of electricity, such as a tree falling into a transmission line, operators must make quick adjustments to maintain the grid’s stability, preventing potential overloads or blackouts.

One tool available to grid operators is known as a remedial action scheme. RAS is a set of controls that quickly adjusts generation or transmission to proactively prevent overloads and potential blackouts. This tool is most often used when there is a significant change in transmission capability created by a major system disruption, also called a contingency event, which can require taking generation offline.

Through a new grid modernization project, BPA is automating RAS, enabling the federal transmission system to be operated more dynamically. This will help accommodate more variable resources being added to the system, namely renewables like wind and solar, and new markets, like the Western Energy Imbalance Market.

The use of RAS on BPA’s transmission grid is not new, but for most of the federal transmission system, operators have to manually set up generators to be ready – or “armed” – to go offline in a contingency event. In 2017, before BPA’s grid modernization initiative, the agency had some early success with automated RAS arming on lines along the Interstate-5 transmission corridor. This resulted in more efficient and optimized operation of this stretch of transmission line. But the continued increase in wind and solar generation, coupled with the demands of emerging energy imbalance markets, requires a system-wide, automated adjustment of BPA’s RAS settings to maintain efficient and reliable power transmission.

Historically, due to the manual nature of the system, RAS arming was set hourly and has been done in larger blocks with conservative margins built in. As BPA prepares for potential participation in markets that operate on five-minute increments, it will be automating RAS arming across the grid. Automation allows for a complex set of rules to be created that determine which generators are set to go offline in response to a contingency or disruption. The settings are based on the current system conditions, such as planned outages and the amount of power being transferred on the grid. This will not only result in more reliable transmission service to customers, but help reduce expenses resulting from lost generation.

“The project will increase reliability by reducing arming errors and arming requirements in real-time,” said Karl Knoll, RAS program manager for BPA.

Next in line is automating RAS arming for the alternating current and direct current interties that connect the Northwest and California by June 2020, and then the western Montana transmission corridor in 2021.

The RAS automatic arming project is one of several grid modernization projects that support the implementation of BPA’s strategic goals to modernize federal power and transmission system operations and supporting technology, and to provide competitive power and transmission products and services.