PIS Compensator Based Current Control for Three-Phase Utility Interface Converters

Three phase voltage-source PWM converters are used as a utility interface. In such a case, the converter line currents are required to track sinusoidal references synchronized with the utility grid without a steadystate error. In this paper a current control method based on a sinusoidal internal model is employed. The method uses a sine transfer function with a specified resonant frequency, which is called an S-compensator. The combination of a PI compensator and an S-compensator is called a PIS compensator. The PIS compensator ensures that the steady-state error in response to any step changes in a reference signal at the resonant frequency and zero hertz reduces to zero. Experiment was carried out using a 1kVA prototype to verify the usefulness of the PIS compensator. Three utility-interface-converters, a voltage source PWM rectifier, an active filter, and STATCOM, were examined. Almost perfect current tracking performance without a steady-state error was observed.