仿真分析中负荷模型对特高压联络线峰值功率转移比的影响

Influence of Load Model on UHV Tie-line Peak Power Transfer Ratio in Simulation Analysis

为了寻找仿真分析中影响特高压联络线峰值功率转移比的关键因素,从负荷模型的角度研究了仿真分析和实际系统中特高压联络线峰值功率转移比的差异。在不同负荷模型产生不同阻尼比的基础上,从静态负荷模型的表达式出发,首先对比了恒阻抗、恒电流、恒功率3种负荷模型的电压特性,并分析了电压特性对峰值功率转移的抑制作用,进一步研究了转移比的差异对直流闭锁安全控制策略中切负荷量的影响,即转移比较大时所需的切负荷量较大,反之切负荷量较小。不同负荷模型计算所得转移比有48%的差异,充分说明负荷模型是仿真分析中影响转移比的关键因素之一。因此负荷模型对转移比仿真结果的准确性至关重要,建议全网开展负荷模型校核工作。

In order to find out the key factors that affect UHV tie-line peak power transfer ratio in simulation analysis, we studied the difference of UHV tie-line peak power transfer ratio between simulation analysis and practical system from the perspective of load model. Using different damp ratios because of different load models, and starting from the expres- sion of static load model, we firstly compared the load voltage characteristics of three kinds of load model including constant impedance load, constant current load, and constant power load. We also analyzed the voltage characteristics which acted as a disincentive to peak power transfer ratio. Furthermore, we investigated the influence of transfer ratio difference on control strategy about load shedding of DC blocking fault.The results reveal that the load shedding is larger when transfer ratio is larger, otherwise, the load shedding is fewer. The 48% large enough transfer ratio difference illus- trate fully that the load model is one of the key facts that affect transfer ratio in simulation analysis, Due to the importance of load model to the accuracy of simulation result of transfer ratio, it is suggested all loading models should be verified.