基于行波固有频率的VSC-HVDC直流输电线路双极短路故障保护与定位

Fault protection and location of bipolar short-circuit in VSC-HVDC transmission line based on natural frequency of traveling wave

提出了运用希尔伯特-黄变换(Hilbert-Huang transform,HHT)对电流进行频谱分析获取固有频率的方法,实现对VSC-HVDC直流输电线路双极短路故障的保护与定位.在高压直流输电线路双极短路故障条件下,对输电线路两端采集到的双极电流相量进行相模变换得到电流模量,从线模电流分量频谱分析结果中提取固有频率主频率和二次频率,运用输电线路两端的线模电流分量固有频率主频率差作为主保护判据,固有频率二次频率作为辅助保护判据,实现直流输电线路双极短路故障保护;利用固有频率与故障距离之间的关系,完成故障定位.通过PSCAD/EMTDC仿真和Matlab数据分析验证了该方法具有较高的可行性.

A method for obtaining natural frequency of traveling wave was proposed by means of analyzing current spectrum with Hilbert-Huang transform （HHT）, and the protection and location of bipolar short circuit fault in VSC-HVDC transmission line were implemented. In condition of high-voltage direct-current （HVDC） transmission line, phase-model transformation of bipolar current phase gathered at both ends of transmission line was carried out to get the current modulus. The dominant frequency and secondary fre- quency of the natural frequency were extracted from the result of spectral analysis of line mode current component and then, the difference between the dominant natural frequencies at both ends of the transmis- sion line was used as the primary Criterion and the secondary natural frequency was utilized as secondary criterion to realize the protection of bipolar short circuit fault. The relationship of natural frequency to fault distance was used to complete fault location. By means of PSCAD/EMTDC simulation and data anal- ysis with Matlab, it was validated that the proposed method would possess a higher feasibility.