中文摘要：

基于集群风电场问无功电压耦合较强、通信条件较差的特点，提出以双馈风电机组为主、电容器／静止无功补偿器（SVC）为辅，不过分依赖风电机组与风电场自动电压控制系统间通信的集群双馈风电场分次调压控制策略。事先根据电网运行状况计算得到不需实时更新的双馈风电机组的PQ曲线，同步补偿无功功率以应对有功出力的变化，并仅在电网运行状况发生大幅变化时更新PQ曲线；在调节效果不够理想或PQ曲线未更新时，再利用电容器／SVC进行二次调压。通过对中国北方某地区集群风电场的仿真分析，验证了所述控制策略可有效减少风电机组连锁脱网的发生机会，并且其控制效果不受风电机组与风电场自动电压控制系统间通信中断的影响。

英文摘要：

The characteristics of clustering wind farms are strongly coupled between reactive power and voltage of wind farms and poor communication reliability. Based on these characteristics, this paper proposes a graded voltage control strategy. In the control strategy, doubly-fed induction generators （DFIGs） are main reactive power resources because of their high reliable reactive power generation ability and capacitors/static var compensators （SVCs） are auxiliary reactive power resources. This makes the strategy independent of high speed and high reliability communication between DFIGs and wind farm automatic voltage control （AVC） system. According to the grid operation condition, the PQ curve of DFIG is calculated previously. Based on the pre-setting PQ curve, the reactive power output of DFIG is adjusted automatically to eliminate voltage fluctuation caused by change of active power output. Only when the grid operation condition changes significantly, the PQ curve need to be updated, that means the PQ curve need not be calculated in real time. When the voltage control aim is not achieved or the updating of PQ curve does not finish, capacitors/SVCs are then used to control voltage, which is called the secondary voltage control. Simulations on a real clustering wind farms in northern China is carried out. The results show that the probability of wind generators＇ cascading disconnection from power grid is reduced effectively with the proposed graded voltage control strategy. Communication failures between DFIGs and wind farm AVC system have no influences on control effect.