双馈风电机组短路特性及对保护整定的影响

摘要

风电场运行方式多变,对保护整定提出了新的要求.短路特性是保护配置的前提和依据.针对双馈风电机组,讨论了其数学模型和电磁暂态过程;建立了风电场联络线接地故障时,风电场提供的短路电流以及电流保护整定的表达式,对影响风电场故障特性和保护配置的主要因素进行了分析.参照实际风电场运行情况,以PSCAD/EMTDC为平台建立了风电场并网运行的仿真模型,研究了控制策略、风电场投入系统容量、机组类型对故障特性和保护整定的影响.仿真结果与理论分析相吻合,表明风电场保护整定应综合考虑上述影响因素,以提高风电场继电保护动作的有效性和可靠性.%Different operating conditions of wind farm impose new challenges on the setting of protection relay. Short-circuit characteristic is the basis of relay protections. The mathematical model and electro-magnetic transients of a doubly fed induction generator (DPIG) are discussed. The setting of protection relay and the sequence current model of wind farm are established when fault is present in the grid connection line. The main factors that influence the short-circuit characteristic of wind farm and the relay setting are analyzed. Taking a practical wind farm for example, the grid-connected simulation model is established on the PSCAD/EMTDC platform. Above influence factors of faulty characteristic and protection are studied, including control strategy, capacity, wind speed and type of generator. Simulation results are identical with theoretical analysis. These influence factors should be considered in the protection design of a wind farm. It will help to enhance the effectiveness and reliability of the protection.