新型直流输电行波电流极性比较式方向保护

为克服现有直流输电线路行波保护原理上存在的缺陷,基于现有行波保护方案的分析和仿真,改进了电流极性比较式方向保护方案。该方案引入了数学形态学梯度技术以提高方向保护的动作性能和准确反映暂态行波信号的突变时刻;且集故障定位与保护于一体。6个具有代表性算例的仿真比较表明,该方案能可靠区分直流输电线路区内、外的各种故障,对近距离故障、高阻接地故障等传统方法中难于准确定位的故障类型给出较准确的结果。

New Directional Protection Based on Traveling Wave Current Polarity Comparison Used on HVDC Transmission Line

HVDC transmission is powerful,low cost lines and good performance,which is an important means of high-voltage,large-capacity,long-distance power transmission in developed worlds.Failure to take immediate measures in the event of line failure will threat to the security of the entire system,so when DC fault lines occur,rapid and reliable protection must work in a few milliseconds.On the basis of analyzing and simulating actual traveling wave protective algorithm of HVDC transmission line,the paper points out its shortage and analyzes material reasons.In view of theory of shortage of actual traveling wave protection,this paper introduces and improves the protection algorithm of current polarity comparison traveling wave protection.And the paper introduces mathematical morphology in order to advance motion capability of traveling wave protection and well and truly reflects the characteristic of traveling wave signals;it also introduces a new protection algorithm with fault location.In this paper,six typical examples are simulated.The results of the simulation shows that the algorithm is able to not only distinguish inside and outside fault of HVDC transmission line,but also provide well and truly fault distance to near distance fault and large resistance grounding fault,the normal method actually are hard to accurately provide fault distance.The program is not only can distinguish reliably between inside and outside of the fault zone,but also can locate accurately.As a result of the mathematical morphology,the new method proposed in this paper,has advantage of simple real-time,high speed and low delay.