Active and Reactive Power Controller for Single Phase PV Grid Connected Inverter with LCL Filter

Abstract

This thesis work is concentrated on Photovoltaic system connected with grid by an inverter to control Active Power and Reactive Power independently and reducing THD using LCL filter. Many exciting methods to control power are based on synchronous reference frame transformation, this method requires information on phase angle given by Phase-Locked loop (PLL). At first PV cell characteristics are drawn that help in making the proposed Photovoltaic system. PLL is avoided and a controller is designed for single phase grid connected inverter system connected with a LCL filter in stationary reference frame. To achieve necessary performance with independent control of active and reactive power injected in the grid the decoupling control strategies is adopted. As compared with orthodox control scheme of controlling power for single phase PV grid present scheme is highly reliable, fast in response and active and reactive power is controlled independently. Present control algorithm is easier and simpler as this scheme is implemented in stationary reference frame. To confine high resonant peak value active damping technique is used in the designed current controller. LCL filter designing has been done in such a way to reduce the net THD and total losses taking place in the inductor of the filter. Switching scheme of the inverter and LCL filter are used to obtain sinusoidal output phase voltage. Lastly, the proposed control scheme helps in controlling the THD and independent control of active and reactive power are achieved without PLL in the system. Dynamic performance of the system is analysed and various waveforms are studied using MATLAB/Simulink 2014a