Power Quality Improvement of the Grid System with Advanced Hysteresis Controller Design

In the power system the use of the nonlinear loads has increased the harmonics leading to serious problems such as low power factor, over heating of the distribution side transformers and disturbance to the load connected to the same point of common coupling. Active Power Line Conditioner with a power circuit of voltage source inverter connected to a DC link capacitor is used to reduce the harmonics. The Performance of the Active Power Line Conditioner depends on the controller used for the switching pulse generation. In this paper Synchronous Reference Frame method is used for the extraction of the reference current and hysteresis current controllers of two types have been used separately for switching pulse generation .The performance of the two types of hysteresis current controller such as fixed Hysteresis current controller and Adaptive Hysteresis current controller for the Active Power Line Conditioner have been analyzed under transient load condition in terms of the Source current settling time and Total Harmonic Distortions. In the System with Fixed Hysteresis Current Controller for the Active Power Line conditioner the source current takes more time to settle and the THD values obtained are above the standard IEEE 519 harmonics limit whereas in the case of the Adaptive Hysteresis Current Controller the source current settles faster and the Total Harmonic Distortion values are below the standard IEEE 519 harmonics limit. Hence the performance of the Adaptive Hysteresis Current Controller for Active Power Line Conditioner is good compared to the Fixed Hysteresis Current Controller in Harmonics Compensation under the transient load conditions.