Development of Variable Speed Wind Turbines Connected to Grid for Optimum Utilization and Power Quality Improvement using Seven-Level Inverter

Abstract: This paper presents an improvement technique for the power quality of the electrical part of a wind generation system with a Permanent magnet synchronous generator (PMSG) which aims to optimize the utilization of wind power injected into weak grids. To realize this goal, an uncontrolled rectifier-digitally controlled inverter system is proposed. The advantage of the proposed system is its simplicity due to fewer controlled switches which leads to less control complexity. It also provides full control of active and reactive power injected into the grid using a voltage source inverter (VSI) as a dynamic volt ampere reactive (VAR) compensator. A voltage oriented control (VOC) scheme is presented in order to control the energy to be injected into the grid. In an attempt to minimize the harmonics in the inverter current and voltage and to avoid poor power quality of the wind energy conversion system (WECS), an LC filter is inserted between VOC VSI and the grid. MPPT controllers used for extracting maximum possible power in WECS. Simulation is carried out using MATLAB Simulink.

Keywords: Permanent magnet synchronous generator (PMSG), voltage source inverter (VSI), dynamic volt ampere reactive (VAR) compensator, voltage oriented control (VOC),wind energy conversion systems (WECS), maximum power point tracking (MPPT).