Active and Reactive Power Control of a Grid Connected Photovoltaic Power System

Abstract

The world has been traditionally dependent on non-renewable sources of energy for industrial applications and other daily domestic applications. The modern world is moving fast towards greener sources. Various ongoing research works are dedicated towards meeting the demands of local loads with help of green energy. Solar energy is one of the most abundantly available forms of renewable energy. But extracting power from solar photovoltaic arrays according to the demand of the load under changing grid conditions and environmental conditions has been a challenge. In this work, active/reactive power control and maximum power point tracking control strategies are investigated. First a working model of solar array is developed and simulated using MATLAB/Simulink. This model is further used for our control strategies investigation purposes. The developed solar array is investigated under varying solar irradiation and varying temperatures. The effect of these factors on voltage, current and consequently on power is observed. A solar photovoltaic array of 100KW is used for simultaneous testing of active/reactive control and MPPT control. The active and reactive power control of photovoltaic array is implemented usually when the available solar power is sufficient, the active and reactive power is controlled in such a way that it follows the load‘s demand characteristics. The photovoltaic array acting as generator should be able to mitigate the sudden change in load demands successfully which is tested by simulating the load change conditions in MATLAB. This active/reactive power control is relatively simpler as it is a single stage configuration with an inverter. The inverter is responsible for controlling, processing and delivering the solar power to the load side efficiently. The MPPT control is investigated under changing solar irradiation from 800W/m2 to 1000W/m2 .The sudden injection in power due to increase in irradiation is seen. The solar photovoltaic array tracks the maximum power and delivers it to the load efficiently. The power at AC and DC sides of the inverter is verified. This two stage configuration is more complex in nature with three control loops. One loop is exclusively for MPPT control. The other two loops are for inverter power control and indirect control of solar photovoltaic voltage and inverter voltage. The ability to deliver maximum power under changing irradiation of the solar photovoltaic generator is simulated with help of MATLAB/Simulink.