Modified Power Balance Theory for control of DSTATCOM

In this paper, a control algorithm based on Power Balance Theory (PBT) is modified to control the DSTATCOM. A 3-leg VSC (voltage source converter) with a zigzag transformer is used as a DSTATCOM (Distribution Static Compensator) for compensation of the reactive power, harmonic currents, unbalance loads and the neutral current in three-phase four-wire distribution system. The modified PBT based control algorithm is used for the extracting the reference source currents for the voltage regulation at PCC (point of common coupling). With the proposed algorithm, simulations are performed for various load conditions such as a reactive linear load, an unbalanced load and a non-linear load in Power Factor Correction (PFC) mode as well as in Zero Voltage Regulation (ZVR) mode in MATLAB environment using SIMULINK and Sim Power System (SPS) toolboxes. Test results on a developed hardware prototype of DSTATCOM are also presented to validate the control algorithm and topology for load compensation.