Load frequency control of a multi-area system incorporating distributed generation resources, gate controlled series capacitor along with high-voltage direct current link using hybrid ALO-pattern search optimised fractional order controller

摘要

The power output from the wind turbine in distributed generation (DG) resources is intermittent in nature, which adversely affects the system frequency in an interconnected system. Hence, it is important to study the system dynamic performance when DG resources are connected to the existing power system. This study presents the load frequency control of the three-area thermal-thermal-hydro system with DG resources in area 1. Proportional integral fractional derivative (PID mu) controller is proposed as a secondary controller. System dynamics are compared among integral, proportional integral (PI), PI derivative (PID), fractional order PID ((PID mu)-D-lambda) and PID mu controllers whose parameters are optimised simultaneously using nature inspired ant lion optimiser (ALO) technique. The analysis shows the competitive performance of (PID mu)-D-lambda and PID mu controllers. Furthermore, the PID mu controller parameters are optimised using hybrid ALO-pattern search technique, which outperforms the ALO optimised PID mu controller. A flexible AC transmission system device called gate controlled series capacitor performs better than an interline power flow controller. The studies show that the gate controlled series capacitor placed in all lines is its optimal location. The system dynamics are improved considerably with the incorporation of high voltage direct current link, the transient droop of the hydro governor. The PID mu controller effectively handles the parametric variations, random load and wind power profiles.