基于灵敏度的变流器弱电网适应能力评估方法研究

Research on Evaluation Method for the Adaptability of the Converter to Weak Grid Based on Sensitivity

变流器的弱电网适应能力近年来被广泛关注,对其弱电网适应能力进行评估十分重要。针对目前广泛采用的相位裕度和幅值裕度难以真正反映变流器弱电网适应能力的问题,首先建立了变流器的诺顿等效模型,基于阻抗比判据引入了系统灵敏度指标,从理论上分析了系统灵敏度与变流器弱电网适应能力间的定性关系,结果表明系统灵敏度越小则变流器的弱电网适应能力越强,在此基础上提出了基于灵敏度的变流器弱电网适应能力评估方法,最后通过仿真验证了理论分析和所提出的弱电网适应能力评估方法的正确性。

In recent years,the adaptability of the converter to the weak grid has been widely concerned,and it is very important to evaluate the adaptability to the weak grid.Aiming at the problem that the widely used phase margin and amplitude margin can′t really reflect the adaptability of the converter to the weak grid,the Norton equivalent model of the converter is firstly established.Based on the impedance ratio criterion,the system sensitivity index is introduced,and the qualitative relationship between the system sensitivity and the adaptability of the converter weak grid is analyzed theoretically.The results show that the smaller the sensitivity of the system,the stronger the adaptability of the converter to the weak grid.On this basis,a sensitivity-based adaptability assessment method of converter weak grid is proposed.Finally,the correctness of the theoretical analysis and the proposed weak grid adaptability assessment method are verified by simulation.