Wind Farm Electromagnetic Dynamic Model and Outgoing Line Protection Relay RTDS Testing

Large-scale wind farm usually contains hundreds of wind turbines, which is directly integrated to the high voltage transmission network through long distance transmission line. Because of the different control strategy, the electrical information between the wind generator and conventional synchronous machine is very different during the external shortcircuit fault conditions. And due to the excessive number of wind turbines, it's scarcely possible to simulate the electromagnetic transient process of a complete wind farm model because of the limit of the hardware source. In order to study the impact of the wind farm on the existing protection relay of the network, it is an important issue to establish a suitable electromagnetic dynamic equivalent model of wind farm to describe the electromagnetic transient process of the wind farm not just a single wind generator. Doubly-fed induction generator (DFIG) wind turbine is established in this paper on the RTDS platform, and a scheme is proposed to establish a suitable electromagnetic dynamic equivalent model of wind farm based on the model above. Finally the equivalent model is established and verified. A power grid model integrated with wind farm equivalent model is built on the RTDS platform. The electrical information of the high voltage feeder of the wind farm is input to really protection relays. A closed-loop protection relay-testing experiment is accomplished on wind farm outgoing line to study the impact of the wind farm on the existing protection relay. Performance under different short circuit fault condition is tested, and finally typical misstrip and maloperation cases are analyzed.