On Optimizing the Transient Load of Variable-Speed Wind Energy Conversion System During the MPP Tracking Process

In order to increase the annual energy yield of a variable-speed wind energy conversion system (WECS), maximum power point tracking (MPPT) control is required at below the rated wind speed. However, the only aspect that has been paid attention to by most of the researchers is the way to accelerate the MPPT speed. In fact, the research of this paper finds out that the faster the MPPT speed is, the larger transient load the turbine shaft bears. Thus, attempts are first made to find out the relationship between the MPPT speed and the transient load through quantity analysis. Then, a principle to choose a proper bandwidth of the MPPT system is given out to optimize the transient load. Furthermore, to ensure that the system can track the varying winds at the designed bandwidth, the design details on how to make the MPPT bandwidth constant are also proposed in this paper. Finally, a 1.2-kW variable-speed WECS, which is based on a permanent-magnet synchronous generator, is established in the laboratory. Theoretical analysis is verified by experimental results performed by it.