A Prototype Development of Control Strategy for Power Conditioning Unit Enabling Current Limitation during FRT

Abstract

In order to study operation of grid connected power converter during unsymmetrical faults, power quality and voltage control plays very important role. At the time of unbalanced voltage sag, active and reactive power consists of contents of double frequency and non-sinusoidal current injection. This paper explains a control strategy for dc link voltage of power conditioning unit (PCU) during unsymmetrical grid faults. By using control method, PCU injects sinusoidal currents during unsymmetrical faults. Current limitation method is suggested here, which is very easy and effective, with the help of which we can limit injected currents to its rated value efficiently in fault condition. Fault ride through (FRT) operation is confirmed to avoid the triggering of overcurrent protection. For dc-dc converter, a Non-MPPT operation mode is suggested to get it enabled under severe fault condition, when converter is not capable of handling maximum PV power. A prototype according to control strategy is developed by using Solar PV emulator with Solar Pro software, Semikron make three phase inverter, boost converter, DSP TMS320F2812 integrated with CCS and Matlab and with MOSFET driver circuit. The set up is tested by using various testing equipments. Experimental results are also verified with simulation results.