Rotor Speed Stability of Grid Connected Wind Energy Conversion Systems

This paper examines the dynamics of grid connected wind energy conversion systems under the concept of ‘rotor speed stability’. The majority of wind turbines installed in India have induction generators, which are directly connected to the grid. Consequently, wind turbines interact with the power system in a way that differs from synchronous generators. Therefore, it is more appropriate to study the impacts in terms of rotor speed stability that focuses on torque-speed dependence of asynchronous generators, similar to the rotor-angle stability that focuses on the torque-angle dependence of synchronous generators. In this paper, the rotor-speed stability of the system considered is analysed for step change in wind velocity, gust speed and for three-phase faults at key locations in the system. Simulation studies are done on an 11-bus radial system, using C++ programming language and the results obtained are presented. The results help to understand the rotor-speed stability phenomena in fixed speed windfarms and could help in designing the rotor-speed stability requirements of such systems.