基于模型识别的交直流混联输电系统时域双端量选相方法

Time-domain double-ended phase selection method for AC/DC hybrid transmission system based on model recognition

针对传统单端量选相元件在交直流混联系统受端交流长线路不适用的问题,文中提出基于模型识别的时域双端量选相方法。首先,利用模型识别的思想,研究故障期间受端带并联电抗器的交流长线路非故障相和故障相的时域模型,经分析可知,非故障相的差动电流和差动电压满足电容模型而故障相不满足。其次,通过Spearman等级相关系数计算各相的电容模型符合度,与门槛值对比进行故障选相。最后,在PSCAD/EMTDC中搭建交直流混联系统模型,从故障类型、故障位置、过渡电阻、采样频率以及噪声干扰等方面对所提故障选相方法进行仿真验证。结果表明,该故障选相方法在受端交流线路各位置故障期间均能快速准确地选出故障相,不依赖直流侧电源特性、不受并联电抗器的影响,并具有较好的抗过渡电阻和抗干扰性能。

To solve the problem that the traditional single-ended phase selection elements are no longer suitable for AC long lines at the receiving end of the AC/DC hybrid system,a time-domain double-ended phase selection method based on model recognition is proposed.Firstly,the time domain model of thenon-fault phase and fault phase of long AC lines with shunt reactors at the receiving end during fault is studied by using the idea of model identification.It can be seen from the analysis that the differential current and differential voltage of the non-fault phase satisfy the capacitance model but the fault phase does not.Secondly,the capacitance model conformity of each phase is calculated by Spearman rank correlation coefficient,and the fault phase is selected by comparing it with the threshold value.Finally,an AC/DC hybrid system model is built in PSCAD/EMTDC,and the proposed fault phase selection method is simulated and verified from the aspects of fault type,fault location,transition resistance,sampling frequency and noise interference.The results show that the fault phase selection method can quickly and accurately select the fault phase during the fault at each position of the receiving end AC line,without relying on the characteristics of the DC-side power supply,without the influence of the shunt reactors,and with good anti-transition resistance and anti-interference performance.