Load Resources to Provide Primary Frequency Reserve Service

With integration of more and more renewable energy resources, it is becoming increasingly difficult to maintain adequate primary frequency control (PFC) capability for a future power grid, especially under low system inertia conditions. Load resources (LRs) equipped with under-frequency relays can participate in PFC supplementing to the governor responses from synchronous units. In this chapter, we describe an energy, inertia, and frequency response reserve (FRR) co-optimization formulation in the day-ahead market where both primary frequency reserve (PFR) from synchronous generators and fast frequency response reserve (FFR) from LRs are procured in a cooperative way to meet the desired FRR need tied to the system inertia condition. First, the performance of the governor-provided PFC is evaluated as a benchmark to quantify the effectiveness of the load-provided PFC at each typical system inertia condition, using the actual dynamic network models and operation data of the ERCOT system. Second, since FFR is more effective than PFR in arresting the frequency decline, an optimization approach is proposed to yield different marginal prices for FFR and its PFR counterpart to award the speed of response. The case study shows the effectiveness of the proposed approach and the correctness of the quantities and prices of the cleared reserve.