Adaptive DC link voltage control of power conditioning unit during FRT

Abstract

The use of power conditioning unit (PCU) in photovoltaic (PV) systems lead to latest technologies in order to manage operation of grid distribution during fault ride through (FRT) operation. An adaptive dc-link voltage control of PCU during FRT is proposed here. The method suggested here for controlling dc link voltage by checking any changes in grid voltage during FRT. This helps in maintaining high modulation ratio (HMR) and attenuation of high frequency harmonics. Control method suggested will help to focus on attenuation of double line frequency dc link voltage ripple at the time of unsymmetrical faults. Double line frequency power ripples need to be exchanged with front end from claiming dc input source; in place to stay with voltage of dc link safely. It is done by making fluctuation in dc input power depending on ratio of voltage drop and input power level. Results are checked in Matlab/Simulink.