CAJ | 학술논문

目前双馈感应风电机组( DFIG)主要通过配备主动式Crowbar保护来实现低电压穿越( LVRT) ,由于电网扰动将打破风电机组原有的转矩平衡条件,由此可能导致风电机组转子加速至超速保护动作值,触发超速保护动作,致使风电机组发生超速脱网,无法实现故障穿越. 本文分析了dq坐标系下DFIG的数学模型和功率解耦控制原理,基于PSCAD/EMTDC仿真平台搭建的DFIG联网仿真系统,仿真分析了因转矩失衡导致机组超速脱网的LVRT失败过程,表明机电暂态过程对机组LVRT有重要影响. 继而提出一种故障期间重启转子变流器、恢复机组功率控制的改进LVRT控制策略,仿真结果表明了改进控制策略的有效性.
목전쌍궤감응풍전궤조( DFIG)주요통과배비주동식Crowbar보호래실현저전압천월( LVRT) ,유우전망우동장타파풍전궤조원유적전구평형조건,유차가능도치풍전궤조전자가속지초속보호동작치,촉발초속보호동작,치사풍전궤조발생초속탈망,무법실현고장천월. 본문분석료dq좌표계하DFIG적수학모형화공솔해우공제원리,기우PSCAD/EMTDC방진평태탑건적DFIG련망방진계통,방진분석료인전구실형도치궤조초속탈망적LVRT실패과정,표명궤전잠태과정대궤조LVRT유중요영향. 계이제출일충고장기간중계전자변류기、회복궤조공솔공제적개진LVRT공제책략,방진결과표명료개진공제책략적유효성.
The crowbar circuit is put into operation to implement low voltage ride through ( LVRT) for doubly fed in-duction generator-based wind turbine ( DFIG) during the fault.If a disturbance triggers the crowbar circuit, it will lead to unbalance of rotor torques of wind generator.The rotor speed may exceed limitation, as a result, the over-speed protection would be triggered and wind generators will trip off from grid.In this paper, the mathematical model of DFIG under dq synchronous rotating coordinate system and the theory of decoupling control of active power and re-active power are analyzed.Based on the simulation system of PSCAD/EMTDC, the DFIG system connected with grid is established.The transient process of DFIG' s over-speed trip-off caused by torque unbalance is simulated and ana-lyzed, which shows that mechanical and electric transient has a major impact on LVRT ability.Furthermore, the tra-ditional LVRT scheme is improved on the basis of restarting rotor-side converter and recovering the control of power during symmetrical grid fault.The simulation results showed that the improved scheme is helpful to enhance the ability of LVRT for DFIG.