Fast and simple power flow control algorithm for a grid connected photovoltaic inverter

Abstract

A fast real and reactive power flow control algorithm for a single phase grid tie photovoltaic inverter is developed. In previously reported methods, which are available in the literatures are complex in nature. And thus the cost and complexity of the control circuit of those methods are high. This proposed method has the design simplicity. Moreover, this method has the benefit of quicker response time. The proposed method is essentially an adaptive method. The algorithm is fast and has the virtue of quick response to the change of required real and reactive power output for the PV inverter. The inverter is current controlled. The voltage (both the magnitude and phase angle) is assumed to be equal to the grid voltage. Current mode asynchronous sigma delta modulation is implemented to ease the controlled sensitivity to the grid current distortion. The algorithm is tested and compared with another method reported in the literature. The comparison has been done for various power changing cases, such as, only real power change while the reactive power is fixe or vice versa etc. A simulation has been performed in MATLAB/Simulink software. A comparison is provided to observe the response behavior of the algorithm. This proposed method is more efficient and can be used effectively in cases for larger abrupt power change. It can give over-frequency protection and support in case of real power mismatch in the grid. But more importantly, in the events of sudden voltage collapses in the utility grid, this method can provide a faster voltage support to the utility grid. It provides more stability to the grid.