Enhancement of power quality by DVR using “ANN Technique” under unbalanced and non-linear loads

The paper discusses the voltage control of a critical load bus using dynamic voltage restorer (DVR) in a distribution system. The critical load requires a balanced sinusoidal waveform across its terminals preferably at system nominal frequency of 50Hz .It is assumed that the frequency of the supply voltage can be varied and it is different from the system nominal frequency. The DVR is operated such that it holds the voltage across critical load bus terminals constant at system nominal frequency irrespective of the frequency of the source voltage. In case of a frequency mismatch, the total real power requirement of the critical load bus has to be supplied by the DVR. Proposed method used to compensate for frequency variation, the DC link of the DVR is supplied through an uncontrolled rectifier that provides a path for the real power required by the critical load to flow .A simple frequency estimation technique is discussed which are Discrete Fourier transform (DFT), ANN controller. The present work study the compensation principle and different control strategies of DVR used here are based on DFT, and ANN Controller .Through detailed analysis and simulation studies using MATLAB. It is shown that the voltage is completely controlled across the critical load.