抑制风机超速脱网的永磁风电场经柔直系统并网的受端交流故障穿越控制策略

AC fault ride-through control strategy of flexible HVDC transmission system for permanent magnet wind farms with over-speed off-grid suppression

永磁风电场经柔直外送的系统发生受端交流电压跌落时,利用转子储能进行风机减载控制的策略可能存在超速脱网问题。对此,提出一种抑制转子超速脱网的风电场减载控制策略。该策略通过转子转速与风机有功功率的关系,对风电机组减载期间的最小有功功率整定,确定风电场的最小有功输出,尽可能地减小直流两侧不平衡功率。严重故障时与直流卸荷电阻配合,快速减载的同时减小卸荷电阻承担的容量。搭建了基于某型号的永磁风电机组构成的风电场经柔直外送的仿真模型,对所提控制策略与传统控制策略进行仿真对比分析,验证了所提控制策略的有效性。

When voltage drop occurs in the receiving AC network of a permanent magnet wind farm connected flexible DC system,the strategy of using rotor energy storage to reduce the load of the wind turbine may have the problem of overspeed off-grid.A load shedding control strategy for wind farms is proposed to suppress rotor overspeed and disconnection.This strategy determines the minimum active power output of the wind farm by adjusting the minimum active power during the load shedding period of the wind turbine based on the relationship between the rotor speed and the active power of the wind turbine,and minimizes the unbalanced power on both sides of the DC as much as possible.In case of serious faults,it is combined with a DC braking resistor to quickly reduce the load while reducing the capacity borne by the braking resistor.Simulation examples of a certain model of permanent magnet wind turbine for flexible HVDC transmission system are constructed to compare the proposed control strategy with the traditional control strategy,and the simulation results verifies the effectiveness of the proposed control strategy.