Load Frequency Control of Interconnected Power System Using Particle Swarm Optimization Based Disturbance Observer-Enhanced PI Controller

Load frequency control is a vital control problem in power system operation and control. The primary purpose of load frequency control is to keep power system frequency at a nominal value and control net power interchange between power system tie-lines at predetermined limits during load variations or disturbances. One common proposed control method for load frequency control is the linear quadratic regulator (LQR) feedback controller. However, all the state variables may not always be available and measurable, limiting the application of the LQR controller. Therefore, A disturbance observer-based controller is proposed to estimate the state variables using the available measurements. The observer-controller gains are optimized by particle swarm optimization. The proposed controller has been validated in a well-known and widely used power system test case, Kundur's two-area 4-machine 11-bus power system and 10-machine IEEE 39-bus power system implemented in Matlab® and Simulink®, under different faulted conditions, and load disturbances. Furthermore, simulation results produced faster frequency control loop stabilization with minimal frequency nadir, which proved the effectiveness of the proposed controller in an interconnected power system.