A Compensation Strategy Based on Consumer's Voltage Unbalance Assessment for a Distribution Static Synchronous Compensator

This paper presents a new control algorithm for a distribution static synchronous compensator (DSTATCOM) based on consumer's voltage unbalance assessment. The proposed controller quantifies, in real time, the parcels of voltage unbalances due to the supplier (utility) and consumer by using local measurements of voltages and currents. The compensator mathematical model is used to derive small signal models in such a way to design controllers to compensate for the negative sequence voltage caused by a consumer. Two inner control loops, designed in synchronous reference frame, assure the DSTATCOM tracks the reference signals generated by the voltage controllers. Digital simulation results obtained with an unbalanced distribution network are used to validate the proposed methodology. The comparison of the results shows that the capacity of the compensator can be significantly reduced when only the unbalanced voltage portion caused by the load is compensated.