静态无功补偿对双馈风机串补输电系统次同步振荡特性的影响

Influence of Static Reactive Power Compensation on Sub-synchronous Oscillation Characteristics of DFIG Connected to Series-compensated Power System

静态无功补偿装置会影响风电系统的次同步振荡特性,需要进行深入分析。为此,针对双馈风电经串补外送系统,在电网侧安装并联电抗器和并联电容器,采用阻抗扫描法测取电网侧和双馈风机的总等效阻抗,从阻抗的角度分析了静态无功补偿装置的位置和容量大小对系统次同步振荡特性的影响机理。分析结果表明并联电抗器补偿容量越大对等效阻抗影响越大,安装位置距风机很近时会减小谐振频率并提高谐振点电阻,距风机较远时会使谐振频率和谐振点负电阻绝对值增大,相比之下并联电容器对系统阻抗影响则很小。最后采用时域仿真验证了理论分析的正确性。

The static var compensator will affect the sub synchronous oscillation characteristics of the wind power system and need further analysis. For this purpose, for the DFIG via series compensation transmission system,shunt reactor and shunt capacitor are mounted at the power grid side. The impedance scanning method is adopted to measure the total equivalent impedance of grid side and DFIG. The influence mechanism of position and capacity magnitude of static reactive power compensation device to sub-synchronous oscillation characteristic of the system from the point of view of impedance. It is shown by the analysis result that the bigger the compensation capacity of the shunt reactor is,the bigger to the equivalent impedance is. The resonant frequency can be reduced and the resistance at the resonance point can be improved when the installation position is close to the fan,and the absolute value of resonant frequency and the resistance at the resonance point will be increased when the installation position is far from the fan. However,the influence of shunt capacitor on the system impedance is very small. Finally,the correctness of theoretical analysis is verified by the time domain simulation.