Invited Talk: Grid Service Provision with Inverter-Based Renewable Resources

Inverter-based renewable resources have the potential to provide secondary grid services such as frequency and voltage support. Variations in transmission frequency or voltage within certain frequency bands, for example 0.1 to 2 Hz, can be suppressed through inverter power modulation assuming low-latency real-time feedback is available. First, we present experimental results that illustrate this idea using synchrophasor-based feedback to modulate a Vestas wind turbine in Lubbock, TX. Results here show that inter-area frequency oscillations can be counteracted with no net loss of steady-state turbine output by adding and subtracting from the turbine’s spinning potential energy. Next we explore how similar inverter modulation services could be provided by large solar installations. We examine some of the key differences and challenges to solar-based services compared to wind-based, including design issues for grid instabilities over larger bandwidths and the tradeoffs between designs that utilize a small amount of storage vs operating the solar installation at less than 100% steady-state capacity. We also note that solar installations can in fact be a cause of grid instabilities, forcing operators to curtail. Inverter-based feedback stabilization may therefore enable higher overall output over existing transmission infrastructure.