Secrets of Successful Integration: Operating Experience With High Levels of Variable, Inverter-Based Generation

Date Published: November 2019

Authors: Debra Lew, Drake Bartlett, Andrew Groom, Peter Jorgensen, Jon O’Sullivan, Ryan Quint, Bruce Rew, Brad Rockwell, Sandip Sharma, and Derek Stenclik

This paper compares the ancillary services strategies across seven system operators around the world. Each of these systems was responding to a high level of variable energy resources and/or inverter-based resources, and a corresponding decrease in synchronous generation. Each has different political, geographic and legacy factors to overcome. Technical responses include running gas turbines in synchronous-condenser mode to maintain inertia, adding voltage support and fault current contributions, adding storage capacity, using more sophisticated forecasting techniques, and enhancing automatic generation control. Market structure responses include expanding intraday markets, integrating demand-response, holding contingency reserves, and expanding ancillary service products. The paper concludes that each ancillary service response increased the system’s flexibility, and that technical challenges in ancillary services are not true barriers to renewable energy integration. The paper proposes that innovation in business models, rate structures, policy and market designs will advance decarbonization in the electricity sector.

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