基于边界消耗暂态谐波能量的柔性直流输电线路保护新方案

A novel protection scheme for VSC-HVDC transmission lines based on boundary transient harmonic energy

超导型故障限流器在柔性直流输电工程中能有效地限制故障电流的峰值和陡度,类比于传统高压直流输电系统的物理边界。将超导型故障限流器看作是柔性直流输电系统的边界,提出了一种基于边界消耗暂态谐波能量的柔性直流线路保护方案。该保护方案利用正极或负极线路整流侧边界消耗的暂态谐波能量启动保护,利用两极线路的整流侧和逆变侧边界消耗的暂态谐波能量差辨别区内外故障,利用正、负极线路整流侧边界消耗的暂态谐波能量之比进行故障选极。理论分析和仿真结果表明,该保护方案适用于各种工况,几乎不受过渡电阻和故障位置的影响,且对采样率要求低,具有重要的工程应用价值。

Superconducting Fault Current Limiter(SFCL)can effectively limit the amplitude and derivative of the fault current in the Voltage Source Converter-High Voltage Direct Current(VSC-HVDC)transmission engineering.This paper regards SFCL as the boundary of the VSC-HVDC transmission system compared to the physical boundary of the traditional HVDC transmission system,and proposes a novel protection scheme for VSC-HVDC transmission lines based on boundary transient harmonic energy.The transient harmonic energy consumed by the boundary of the rectifier side of the positive or negative line is used as the startup component,the difference of transient harmonic energy consumed by the boundary of both rectifier side and inverter side of the bipolar lines is used to identify the internal and external fault,the ratio of transient harmonic energy consumed by the boundary of the rectifier side of the positive and negative line is used to select the fault pole in the proposed scheme.The theory analysis and simulation results show that this protection performs well under various situations,and it is almost not affected by fault resistance and fault location.In addition,high sampling frequency is not needed in this scheme,having important engineering value.