Frequency compensation for stand alone voltage-controlled DSTATCOM

This paper presents a simple control loop for voltage-controlled DSTATCOMs able to mitigate the effects of grid frequency deviation, greatly increasing the voltage regulation autonomy. The DSTATCOM consists of a three-phase four-wire Voltage Source Inverter (VSI) connected to the grid through a second order low pass filter. The control structure is composed of the conventional loops: three for the output voltage with active damping, and two for dc bus voltages, along to the frequency loop. The inclusion of the frequency loop makes the grid voltage phase information no longer needed. In other words, only the PCC voltage information is needed for the DSTATCOM operation. Experimental results prove its features and the effectiveness of the new loop.