基于MP-RCC的双馈风电机组低电压穿越控制研究

Low-voltage Ride-through Handling in Doubly Fed Induction Generators Based on Model-predictive Rotor Current Control

对于风电并网系统,双馈风电机组电网侧电压严重跌落容易在风机转子侧形成峰值涌流,损坏变流设备,并造成风机脱网。因此提出了模型预测转子电流控制(model predictive rotor current control,MP-RCC)与动态电压恢复器(dynamic voltage restorer,DVR)的协调控制策略,以提高双馈风机在故障情况下不脱网运行的能力。首先,根据双馈风电机组的工作原理,建立其预测控制状态空间模型;其次,在双馈风机转子侧施加MP-RCC,从而实现双馈风电机组低电压穿越时转子电流对参考值的迅速跟踪;最后,引入动态电压恢复器,在低电压穿越期间补偿电网压降,维持机端电压,以保证风电机组在MP-RCC控制下稳定运行。通过Matlab/Simulink对所提控制策略进行了仿真验证,结果表明,MP-RCC与DVR的协调策略可以有效应对双馈风电机组的低电压穿越过程,提高双馈风电机组的故障穿越能力。

For the grid-connected wind power system, a severe voltage sag on the grid side of the doubly fed induction generators may induce a peak inrush current in the rotors,which damages the converters and causes wind turbine disconnection from the grid. To prevent these problems, we propose a strategy to coordinate the model predictive rotor current control(MP-RCC) and the dynamic voltage restoration for improving the ability of the wind turbines to remain its connection to the grid under faults. First, by considering the wind turbines operation, we establish a predictive control state-space model. Second, the MP-RCC is applied to the rotor of the wind turbines for the fast tracking of the rotor current to its reference value during the low-voltage ride-through. Finally,a dynamic voltage restorer compensates the grid voltage sag and maintains the terminal voltage during the low-voltage ride-through to ensure the stable operation of the wind turbines under the MP-RCC. Simulation results show that the proposed strategy to coordinate the MP-RCC and the dynamic voltage restoration effectively handles the low-voltage ride-through of the doubly-fed induction generators to improve the fault ride-through capability.