Improved Optimal Decentralized Load Modulation for Power System Primary Frequency Regulation

Abstract

Nowadays the interest in smart load technologies for primary frequency regulation is spurred due to the increasing penetration of renewable energy resources. In this paper, an improved optimal load control (improved OLC) is introduced by applying a multiobjective optimization-based gain-tuning method to the conventional OLC approach. The objective is to minimize the frequency nadir, time response, steady-state error, total load shed, and aggregated disutility of controllable loads subject to power balance over the network. Simulation results indicate that enabling a multiobjective optimization-based gain-tuning procedure in the OLC approach can provide better power system frequency regulation. Time-domain analysis confirms the superior performance of improved OLC in terms of frequency nadir (Hz), steady-state error (Hz), control effort, and NERC-based performance metrics (MW/0.1 Hz), with detailed load and wind farm models. Furthermore, small-signal analysis demonstrates that the improved OLC enhances the system closed-loop performance and stability margins by increasing the damping ratio of the system's critical modes.