为缓解数字仿真效率与精度的突出矛盾,提出一种频率响应降序自适应分段匹配方法,以实现对高压直流线路短路故障的快速计算。考虑直流系统的实际拓扑和相关元件的频变特性,首先建立用于直流故障分析的相频域分析模型,并由此提取相关阻抗/导纳的离散频率响应;提出对阻抗离频率响应按照降序的原则分段进行等值的方法,降低匹配过程产生的累积误差;为灵活处理由故障条件不同带来的随机性问题,为每段的匹配技术提供了一种参数自适应选择方案。算例表明,相比传统的数字仿真方法,所提方法能够在保持较高的计算精度的基础上有效提高计算效率。
In order to alleviate the sharp contradiction between the accuracy and efficiency of traditional digital simulations, this paper proposed a descending-order adaptive frequency-partitioned fitting algorithm of frequency responses for fast short-circuit calculation on HVDC transmission lines. With consideration of the actual HVDC project topology and the frequency-dependent nature of related components, a mathematical model in phase and frequency domain for dc-line faults and the extraction of discrete frequency responses for related impendence /admittance were firstly proposed. Then this paper proposed a frequency-partitioned fitting method for the discrete frequency responses of impendence to compute section-by-section approximants according to the principle of descending order, which would reduce greatly the accumulated errors in the fitting process. In order to handle with the random problem caused by different fault conditions, a related parameters adaptive selection scheme for the fitting technique on every section was also presented. Numerical examples show that the proposed method has a huge advantage in saving CPU time on basis of keeping high accuracy over traditional simulations.