Comparative analysis of the Pi, Fuzzy and Hybrid Pi-Fuzzy controllers Based DVR

Due to complexity of power system combined with other factors such as increasing susceptibility of equipment, power quality is apt to waver. With electricity demand growing, low power quality is on the rise & becoming notoriously difficult to remedy [1]. Distribution system needs to be protected against voltage sags, dips & swells that adversely affect the reliability & quality of power supply at the utility end. The Dynamic voltage restorer (DVR), which has been utilized in optimized way so as to improve performance, has been put under new technique of sag detection. Various control strategies have been developed to mitigate the voltage sag/swell and the mitigation of unbalanced voltage dips. The applications of Fuzzy logic controller have taken new dimension in various fields. In this thesis, full panorama of power quality disturbances, with background theory and guidelines on measurement procedures & problem solving techniques are presented. The essentials of control scheme with immediate voltage generation to regulate the unbalance voltage phase in three phase system and a tested method to improve the reliability within the distribution system is presented. The 11kV system is controlled by linear & non-linear techniques and their performance levels are compared. The simulation results of the recommended system states the better reliability & compatibility of non-linear techniques with non-linear loads than the system with linear techniques with non-linear loads. The capability of DVR is demonstrated using MATLAB/SIMULINK simulation models. From the obtained results, we have considered the feasibility & practicability of the approach for the linear and non-linear load under voltage sag condition. LIST OF ABBREVIATIONS CPD Custom Power Device DVR Dynamic Voltage Restorer PI Proportional Integral FACTS Flexible AC Transmission System SVC Static VAR Compensator STATCOM Static Synchronous Compensator TCSC Thyristor Controlled Series Compensator SSSC Static Synchronous Series Compensator UPFC Unified Power Flow Conditioner IPFC Interline Power Flow Conditioner HVDVR High Voltage Dynamic Voltage Restorer IPM Intelligent Power Module SVPWM Space Vector Pulse Width Modulation VSC Voltage Source Converter PSCAD Power System Computer Aided System EMTDC Electromagnetic Transients Including DC SPLL Software Phase Locked Loop VSVPWM Voltage Space Vector Pulse Width Modulation MOSFET Metal-Oxide Semi-conductor Field effect ESS Energy Storage System FLC Fuzzy Logic Controller THD Total Harmonic Distortion FFT Fast Fourier Transform IEEE Institute of Electrical and Electronics Engineer EPQ Electric Power Quality BESS Battery Energy Storage System SA Surge Arrester SMES Super Magnetic Energy Storage System GTO Gate Turn-Off Thyristor IGBT Insulated Gate Bipolar Transistor IGCT Insulated Gate Commutated Thyristor