Development of a Close Loop Control Strategy for Enhanced Ride Through Capability for DFIG based Wind Energy System

Abstract

Wind energy is becoming a more viable alternative to commercial electricity production owing to its availability, environmental friendliness, and high power generation capacity. Due to the increased importance of wind turbine-based generators, the doubly fed induction generator (DFIG) is gaining increased prominence due to its maximum power extraction capability, variable speed generator operation, and strong reactive power control and resistive capability during low and high voltage fault ride through. newlineThis thesis describes a grid-connected variable speed wind energy conversion system that utilizes a doubly-fed induction generator in combination with back-to-back power electronics converters. The power converters and their controllers regulate the performance of the generator both during normal and faults. It offers a lower cost solution than the full system power rated converter because the power electronic converter is rated only about one-third of the nominal power. newlineThe conventional techniques of maximum power point tracking have model dependency, slow convergence rate and lower system efficiency. In this work, an attempt has been made to overcome the drawbacks of existing techniques and proposes the Adaptive-Neuro Fuzzy Inference System based maximum power point tracking controller. The adaptive neuro-fuzzy inference method is a highly effective technique that incorporates both fuzzy control and artificial neural network concepts. The main objective of this controller is to maximize the stator active power generation. The proposed ANFIS has single input as rotor speed. The instantaneous torque reference is determined as the output from the ANFIS network. A comparative analysis with PI controller shows that the performance of the DFIG improves significantly using artificial intelligence-based controller. newlineDuring grid disturbances like voltage sag, stator terminal voltage decreases with a rapid increase of stator and rotor current due to a sudden inrush of currents. At this instant, mechanical power is almost c