Control of a Stand-Alone Wind Energy Conversion Systemvia a Third-Harmonic Injection Indirect Matrix Converter

A stand-alone doubly fed induction generator (DFIG)-based wind power generation system using a third-harmonic injection indirect matrix converter (THIIMC) is proposed. The THIIMC has the same performance of a back-to-back pulse width modulation converter, but does not require the bulky direct current (dc)-link capacitor. Because of both its compact construction and high reliability, it is very suitable for embedding into DFIG-based wind generators. It also overcomes the drawbacks of indirect matrix converters and improves the reactive power output capability. The THIIMC consists of a rectifier-side converter, an inverter-side converter (ISC), and an active third-harmonic current injection circuit. A direct stator voltage vector control scheme for the ISC provides the desired stator voltage to the loads. The control scheme is designed to compensate the reactive power of the loads based on the THIIMC working principle. Maximum power point tracking control is performed by a battery energy storage system, which is placed in the dc-link of the THIIMC to smooth out the power fluctuations caused by load or wind speed variations. Simulation results demonstrate the performance and feasibility of the proposed topology and control scheme.