含chopper电路的直驱风机响应电网短路的运行特性分析

Operating Characteristic Analysis of Permanent Magnet Synchronous Generator with Chopper Circuit Responded to the Power System Short Circuit Fault

为了分析电网短路时的直驱风电机组运行特性,从数学模型入手,研究了风轮机最大风能追踪控制策略,以及交直交变频器机侧的有功无功解耦控制策略和网侧的电压定向控制策略。为了满足风电机组的低电压穿越要求,采用了直流电容chooper保护电路。电网短路故障时,chooper回路中的卸能电阻能很大程度地消耗短路冲击带来的能量,从而维持直流电容电压稳定。同时参考电流限值器也限制了短路冲击对网侧变频器的影响。在empt-rv中搭建了直驱风机模型,分析了电网三相短路导致并网电压跌落到0.2以下时风电机组的运行特性。仿真结果验证了所采取的控制策略正确性,以及直流电容chooper保护电路的有效性。研究结果对直驱风机并网运行以及电网短路对风机运行特性的影响提供了依据。

In order to analyze the operating characteristics of permanent magnet synchronous generator（ PMSG）impacted by the power system short circuit fault,this paper researches maximum wind energy tracking control strategy of the wind turbine the machine side decoupling control strategy of active and reactive power of the AC-DC-AC converter and voltage orientation strategy of the gird side by mathematical model. For meeting the wind turbine low voltage ride through（ LVRT） requirement,DC capacitor chooper protection circuit is used. When short-circuit fault occurs discharge resistance in chooper circuit can unload the energy,which could maintain the DC capacitor voltage stabilitily. At the same time the reference current limiter can also limit the impaction on the grid side converter by power system short circuit fault. The PMSG simulation model is constructed in emtp-rv platform,and its operating characteristics is simulated in the condition of power system three-phase short-circuit fault,causing the grid voltage drops below 0. 2. The simulation results verify the control strategy correctly and DC capacitor chooper protection circuit effectively. The results provide the basis for the operating characteristic of the PMSG grid-connecting to the power system and the influence of power system short-circuit fault on the PMSG.