LOAD FREQUENCY CONTROL OF SINGLE AREA MULTI-SOURCE POWER SYSTEM USING ATOM SEARCH OPTIMIZED HIGHER ORDER SLIDING MODE CONTROLLER

Abstract

In this paper, a robust load-frequency control (LFC) scheme of a single-area multi-source power system is proposed. To create a realistic multi-source power grid scenario, the power system is augmented with reheated thermal, hydro and gas power generating units. Due to the diverse dynamics and non-linearities of these generating units (such as reheater delays and non-minimum-phase water-acceleration features), standard linear controllers are insufficient to maintain frequency stability during load changes. To address this, a Higher-Order Sliding Mode Controller (HOSMC) using the Second Order Sliding Surface is proposed. The sliding surface coefficients and controller gains are tuned using the Atom Search Optimization (ASO) algorithm, which simulates Lennard-Jones potential forces and covalent bonds in molecular dynamics. Integral Time-weighted Absolute Error (ITAE) is used as the objective function. The performance of the proposed ASO-HOSMC scheme is validated through comprehensive simulation and compared with classical Sliding Mode Controllers (SMC), an ASO-tuned FOPID controller, a DE-optimized PI controller, and an optimal controller. The simulation results show that the proposed controller reduces the frequency deviations and the settling times dramatically and eliminates the steady state error. Robustness and sensitivity analyses demonstrate that the proposed controller maintains high-frequency stability under parameter variations (±25% and ±50% changes in system parameters).