Real-Time Estimation of VPP Equivalent Inertia and Fast Frequency Control

The paper proposes a method to estimate, in transient conditions, the equivalent inertia constant and fast frequency control droop gain of Virtual Power Plants (VPPs). The estimations are obtained based on the frequency and active power variations at the point of connection of the VPP with the power grid. The accuracy of the estimator is enhanced by a novel technique employed to approximate the VPP's equivalent internal reactance, based on the voltage and reactive power variations at the point of connection. The performance of the proposed method is illustrated through a case study based on a modified version of the WSCC 9-bus system.