Stability Enhancement of VSWT-PMSG

Abstract

Until the end of the 1990s, the constant speed concept dominated the market, and it still represents a significant part of the operating wind turbine population. However, recently the variable speed wind turbine generator system (WTGS) is drawing the attention of the power grid operator. The variable speed WTGS uses the power electronic converters that enable decoupling the grid frequency from the real-time rotational frequency, as imposed by the instantaneous wind speed and the wind turbine control system. Variable speed operation enables an optimization of the performance, reduces the mechanical loading, and at the same time delivers various options for active power plant control. Decoupling the electrical and rotor frequencies absorbs wind speed fluctuations, allowing the rotor to act as a (accelerating and decelerating) flywheel, and thus smoothing out spikes in power, voltage, and torque [6].