异步联网下多直流送出系统的功率稳定性分析及评价标准

异步联网后的云南电网属于典型的多直流送出系统。由于直流彼此之间存在相互作用,因此如何评估多直流送出系统的稳定性成为了亟待解决的问题。基于两直流送出系统的准稳态模型,研究了多直流送出系统的最大功率传输曲线,基于该功率曲线给出了多直流送出系统功率稳定裕度的评估指标。进一步地,研究了多直流送出系统的功率稳定性与多直流有效短路比的定量关系,揭示了多直流送出系统功率稳定性与直流相互作用因子的关系,最后给出了多直流送出系统稳定运行的评价标准。分析结果表明,多直流有效短路比<1.2时,多直流送出系统难以稳定运行;多直流有效短路比>2.0时,直流系统通常可以保持较高的功率稳定裕度,相关结论为多直流送出系统的规划运行提供了一定的参考价值。

Analysis and Evaluation Criterion of Power Stability for Asynchronously Interconnected Multi-send HVDC Systems

Asynchronously interconnected Yunnan power grid belongs to a typical multi-send HVDC system. Due to the interactions of each other, how to evaluate the stability of a multi-send HVDC system becomes an urgent problem to be solved. Based on the two-send HVDC systems quasi-steady state model, we studied the maximum available power curve of the multi-send HVDC system. Based on the power curve, an evaluation index of power stability margin of multi-DC transmission system is given. Furthermore, we studied the correlations between the power stability of the multi-send HVDC systems and the effective short circuit ratio, revealed the relations between the power stability of the multi-send HVDC systems and the influence factor, and put forward an evaluation criterion for stable operation of the multi-send HVDC systems. The analyses show that the sending HVDC systems are hard to maintain stable operation when their MIESCRs are less than 1.2 and the sending HVDC systems can maintain high power stability margin when their MIESCRs are greater than 2.0. The corresponding conclusions provide a useful instruction for planning and operation of the multi-send HVDC systems.