Aggregated Frequency Response Model of Regional System Considering Load Frequency Behaviors

Abstract

With penetration of converter interfaced generation, assessment of inherent frequency stability support capability of regional power grids with rich loads and low inertia is becoming increasingly important for power system safety and stability. Considering the features of regional system frequency dynamics, we extend system equivalent frequency model to encompass load frequency behaviors that have been neglected in previous literature. We first propose an equivalent load frequency response model (LFR) to describe frequency behaviors of individual load in power system dynamics. Then, a regional system aggregated frequency response (RSAFR) model is conducted by gathering equivalent models of multiple generators and loads, during which accuracy of multi-load aggregation is proven by mathematical method. Simulation study illustrates loads have great impact on system frequency response, especially with reduction of synchronous generators in the regional system and LFR model can accurately represent composite load frequency behaviors. Furthermore, performance of the RSAFR model in terms of efficiency, accuracy, robustness, and adaptability is discussed. This work is important for furthering our understanding of the role of loads in frequency dynamics and offers a more complete model to describe the relationship between system frequency and active power imbalance.