A new method to point of common coupling voltage control in distribution grid-connected photovoltaic systems

Nowadays, in addition to providing active power to the local loads, photovoltaic systems are helping the grid to control the point of common coupling voltage. In this paper, a new version of instantaneous reactive power theory has been proposed to control the point of common coupling voltage. The advantages of using this method are the absence of phase-locked loop and the application of simple calculations to raise the speed of the system response. Moreover, the proposed method is in such a way so that it allows the system to mitigate the symmetrical and asymmetrical voltage sag and swell; consequently, the quality of power delivered by photovoltaic system to the grid will be improved. On the other hand, the proposed structure, in addition to increasing the reliability of power injection, maintains providing of balanced active power in the presence of unbalanced reactive power without the need to additional controllers. To validate the proposed structure, the system has been tested on IEEE 33-bus radial distribution grid and the results are presented from a dynamic simulation by using MATLAB/SIMULINK. According to the results, the proposed method regulates the point of common coupling voltage with a response time of about 0.2second that is faster than conventional control strategies.