DefinePK

Abstract

In rural areas which are located far from the electrical grid, renewable energy systems such as photovoltaic (PV) energy are investigated. The most popular PV application is solar water pumping for irrigation. DC-DC converter and maximum power point tracking are used because the PV modules output varies widely due to varying weather conditions. The water pump is driven by a three phase induction motor through a voltage source inverter (VSI). However, the control of induction motor is known to be difficult because it's highly non-linear and time variant. One method to mitigate this is by using vector control techniques to control the VSI as they offer a number of benefits including speed control and regulation over a wide range and fast dynamic response. The proportional - integral (PI) controller is most commonly used in the speed control loop of vector control. This paper deals with the design of the speed PI controller parameters (gains) using particle swarm optimization (PSO) technique and compares it with the conventional Ziegler-Nichols (ZN) method. Different objective functions have been proposed which are used to evaluate the optimization algorithm. The optimum solution mainly converges to a minimum error which affects the control parameters such as the maximum overshoot, rise time and settling time of the system. Simulation results are obtained using Matlab/Simulink program for photovoltaic pump application during load variation (pump head and flow rate variation). The results show the advantage of the PSO-based optimization approach.