Indian Journal of Science and Technology

Abstract

Grid connected distributed generators are becoming increasingly popular owing to their reliability. In earlier days, one of the drawbacks in the solar energy sources is the need for energy storage for the system to be utilized for a significant percentage of the day. One way of overcome this disadvantages by utilizing the inverter and its controller circuits for PV based DG units during the day and night times for improving the reactive power compensation and harmonic elimination on its neighboring DG units and the grid by proper exchange of reactive power between the sources. The existing Proportional-Integral controller (PI) and predictive control methods are more dominant in current error compensation. But the conventional type PI controllers normally do not have appropriate compensation from the inverters for the grid connected applications. In this paper a composite controller design comprising of both voltage oriented control and direct power control is developed for the grid side control. The control strategy is based on generation of current reference for current controller by utilizing the separated fundamental component of power to meet the instantaneous power demand at PCC and the power availability at PV sourced inverter. The state space model for the entire scheme is presented and used for simulation. Comprehensive analysis and simulation of the scheme with variations in irradiation, wind speed and customer loads have been presented in this work. The analysis of the scheme for non linear load and three phase fault at PCC for hybrid scheme with PV array and wind generator has been attempted for the first time in this work. The adaptability of proposed controller to work in islanded mode has also been tested. The simulations have been carried out for all these variations and compared with the direct power control and the significance of the proposed work is presented.

Keywords: Composite Power Control, Direct Power Control, Induction Generator, Nonlinear Load, Photovoltaic Inverter, Voltage Oriented Control