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This paper presents Distribution Static Compensator (DSTATCOM) for compensation of unbalanced nonlinear load with dq 0 current controller (using proportional integrator and harmonic compensation regulators) and Sinusoidal Pulse Width Modulation (SPWM) switching. The dq 0 current controller is implemented in Synchronous Reference Frame (SRF) rotating at fundamental frequency and consists of Harmonic Compensation (HC) regulator (realized by sum of Sinusoidal Signal Integrators (SSI)) in parallel to Proportional Integrator (PI) regulator. The SSI provides high gain to specified tuned harmonic frequency and helps in improving filter current tracking performance for harmonic load current compensation. Each SSI in fundamental rotating dq 0 reference frame can simultaneously compensate for two load current harmonics and thereby reducing the computational effort compared to SSI in stationary reference frame. Neutral current compensation, which is required for compensating unbalance in load, is carried out through 0-axis controller. SPWM switching strategy results in switching of inverter switches at constant frequency. This will simplify the design of inverter output filter (L/LC), reduces stress on switches and switching noise. Simulation studies of DSTATCOM load compensation using dq 0 current controller with interface L and LC filters is carried out in Matlab/Simulink and the corresponding results are presented. Experimental studies are carried out on three phase DSTATCOM prototype using dSPACE 1104 with Matlab Real Time Interface (RTI). [ABSTRACT FROM AUTHOR]

This paper proposes a modified four-leg distribution static compensator (DSTATCOM) topology for compensation of unbalanced and nonlinear loads in three-phase four-wire distribution system. DSTATCOM, connected in parallel to the load, supplies reactive and harmonic powers demanded by unbalanced nonlinear loads. In this proposed topology, the voltage source inverter (VSI) of DSTATCOM is connected to point of common coupling (point of interconnection of source, load, DSTATCOM) through interface inductor and series capacitance, unlike the conventional topology which consists of interface inductor alone. Load compensation with a lower value of input DC link voltage of VSI is possible in this modified topology compared to conventional topology. A comparative study on modified and conventional topologies in terms of voltage rating of inverter power switches, switching losses in VSI and power rating of input DC capacitor of VSI is presented. The detailed design aspects of DC link capacitor and interface series capacitor are also presented. The reference filter currents are generated using instantaneous symmetrical component theory and are tracked using hysteresis current control technique. A detailed simulation study is carried out, to compare the compensation performances of conventional, modified topologies using PSCAD simulator and experimental studies are done to validate the simulation results. [ABSTRACT FROM AUTHOR]