Targeted Fast Frequency Response by Decomposing Frequency into Transient and Steady-State Deviations

The increasing penetration of renewable energy sources (RESs) into power systems is reducing the effectiveness of operation, control, and protection schemes traditionally employed in power systems. The decoupling of RESs’ kinetic energy from the rest of the system and, thus, the variability of system inertia pose a critical challenge to maintaining frequency stability. In this paper, a new paradigm is set forth for optimal fast-acting frequency containment (OFFC) through a short yet targeted active power injection. This concept builds upon the innovative idea of decomposing frequency response into transient and steady-state deviations. The core aim of OFFC is to reduce or completely remove the transient frequency deviation without unnecessarily changing the settling frequency. This minimizes the time and efforts required to restore the frequency within the statutory limit while avoiding unnecessary expenditure of turbines’ lifetime. Only after allocating enough resources for removing the transient deviation, the system operators may utilize the remaining power resources (if any) to reduce the steady-state deviation. The system frequency response (SFR) model and the loss of generation size are needed as input to formulate the shape, time, and volume of the targeted injection required. This is readily accomplished by applying the inverse SFR model to the frequency correction required. Extensive simulations conducted on the IEEE 39-bus test system verify the effectiveness and reliability of the proposed method for OFFC.