大规模风电汇集地区风电机组高电压脱网机理

大规模风电场接入弱电网时会降低电网的电压稳定裕度,增加电压调整控制的难度。从实际发生的某次风电机组高电压脱网故障出发,探讨大规模风电经远距离输电线路送出时并网点出现高电压过程的机理,建立风电场远距离并网的等效单机无穷大系统模型,得出风电场并网点电压与送出功率及无功补偿之间的关系,推导出在风电机组恒功率特性下风电并网点电压对电容补偿的灵敏度,证明当风电送出功率增大时其并网点电压的灵敏度也随之增大,说明在风电大发时投入电容补偿后会引起较大的电压增幅,存在风电机组高电压脱网的风险。通过DIgSILENT软件对某实际风电场接入地区电网进行仿真分析,验证上述结论的正确性。

High-Voltage Trip-off Mechanism of Wind Power Generators in District Grids with Large-Scale Wind Power Integration

Integration of large scale wind farms to a weak power grid will decrease the margin of voltage stability and increase the difficulty of voltage control. The high-voltage formation mechanism in the process of long distance transmission of large scale wind power is discussed based on an actual event of high-voltage trip-off of wind power generators. An equivalent single-machine infinite-bus system model is established to simulate the wind farm connection with the power grid through long transmission line and derive the relationship of bus voltage with wind power level and reactive power compensation. It is pointed out that there will be a sharp increase in voltage after capacitor compensation at the limited operation point, which may cause a high voltage and then make wind generators trip-off. A real grid integrated with wind farms is simulated by using the DIgSILENT software to prove the conclusions above.