高压直流输电线路时空暂态拟合保护新原理

HVDC line protection has plenty of problems and flaws. The main protection and the backup protection need to be studied, which can meet the requirements of protections and operate correctly during the whole fault period. This project studies new principles of protection which make space-time transient fitting of the fault electrical quantities on the model of HVDC transmission lines. The theory of equal transfer process of transmission lines is the theoretical basis of the virtual digital transferring link design. And the virtual digital transferring link is an important technical means to improve the accuracy of the HVDC transmission line space-time transient fitting and the protection sensitivity. An new current differential protection scheme for HVDC transmission lines based on space-time transient fitting of voltage is presented, which makes space-time transient fitting of voltage on the non-fault HVDC transmission line and the instantaneous values of the capacitive current can be calculated. Thereby a high-sensitivity and high-reliability HVDC transmission line protection based on pilot relay channel is provided, which can operate correctly during the whole fault period. An new Non-unit Protection scheme for HVDC transmission lines based on space-time transient fitting of the internal fault is presented, which makes space-time transient fitting of the internal fault HVDC transmission line and distinguish between internal and external faults by comparing the space-time transient fitting deviation of the two faults on the basis of the boundary characteristic of smoothing reactors and DC filters at both end of a HVDC transmission line. Thereby a HVDC transmission line protection without channel is provided, which can operate correctly during the whole fault period without dead zone.

现有的高压直流线路保护存在诸多问题，迫切需要研究符合继电保护应用要求的并且能够长期反应故障的主后备保护。本项目首次从基于高压直流输电线路模型拟合故障暂态电气量时空变化规律的角度研究保护新原理。输电线路等传变理论是虚拟数字传变环节设计的理论依据，虚拟数字传变环节是提高直流线路时空暂态拟合精度和保护灵敏度的重要技术手段。提出基于电压时空暂态拟合的高压直流输电线路纵联电流差动保护新原理，拟合无内部故障直流线路电压时空暂态变化规律，从而较精确地补偿直流线路的暂态分布电容电流，实现基于纵联通道的高灵敏度、高可靠性且能够长期投入的直流线路保护。提出基于直流线路内部故障时空暂态拟合的单端量保护新原理，拟合直流线路内部故障的时空暂态变化，借助直流线路两端的平波电抗器和直流滤波器的边界效应，通过内、外部故障时进行时空暂态拟合的差异性判断故障，实现不借助纵联通道、无故障死区且能够长期投入的直流线路保护。

现有的高压直流线路保护存在诸多问题，迫切需要研究符合继电保护应用要求的并且能够长期反应故障的主后备保护。本项目首次从基于高压直流输电线路模型拟合故障暂态电气量时空变化规律的角度研究保护新原理。输电线路等传变理论是虚拟数字传变环节设计的理论依据，虚拟数字传变环节是提高直流线路时空暂态拟合精度和保护灵敏度的重要技术手段。提出基于电压时空暂态拟合的高压直流输电线路纵联电流差动保护新原理，拟合无内部故障直流线路电压时空暂态变化规律，从而较精确地补偿直流线路的暂态分布电容电流，实现基于纵联通道的高灵敏度、高可靠性且能够长期投入的直流线路保护。提出基于直流线路内部故障时空暂态拟合的单端量保护新原理，拟合直流线路内部故障的时空暂态变化，通过内、外部故障时进行时空暂态拟合的差异性判断故障，实现不借助纵联通道且能够长期投入的直流线路保护。