DSP based implementation of a three-phase four-wire DSTATCOM for voltage regulation and power quality improvement

A three-phase four-wire DSTATCOM (distribution static compensator) based on three-leg VSC (voltage source converter) and a star/delta transformer is proposed for voltage regulation in a three-phase four-wire distribution system. The DSTATCOM is controlled to compensate reactive power, eliminate harmonic currents, balances the load and also to mitigate the neutral current. The use of star/delta transformer for interfacing to a three-phase four-wire power distribution system reduces required rating of the VSC for a three-phase four-wire DSTATCOM. The IGBT (insulated gate bipolar transistor) based VSC is capacitor supported and is controlled for the required compensation of the load current. The dc bus voltage of the VSC is regulated during varying load conditions. The control algorithm is based on synchronous reference frame (SRF) theory for generating the gating pulses. The performance of the three-phase four-wire DSTATCOM is validated for voltage regulation along with neutral current compensation, harmonic elimination and balancing of linear loads as well as non-linear loads through hardware implementation using dSPACE, which is based on DS1104 R&D controller and a slave DSP subsystem based on TMS320F240.