Abstract The voltage source converter based multi-terminal high-voltage DC (VSC-MTDC) system is a novel technique that has many advantages over conventional DC systems. However, the widely used half-bridge modular multi-level converter (MMC) is defenseless against DC faults unless the main protection operates fast enough to trip the local DC circuit breaker. For this reason, there is an urgent need to develop high-speed protection schemes apply to the VSC-MTDC. However, many state-of-the-art protection strategies in field applications require the configuration of the fault current limiting reactors at each end of the DC line, which not only increases investment but also has a negative impact on the dynamic response capability of the system. Also, the dilemma between the improving of sensitivity and the ensuring of selectivity of existing protection schemes needs to be further addressed. In this study, a novel permissive pilot protection scheme is proposed based on the energy ratio between the backward traveling wave and the forward traveling wave. The proposed protection scheme requires only a logic signal from the remote end, avoiding the heavy burden caused by the data exchange and synchronization. Simulation results indicate that the proposed protection has an adequate reach to cover the entire length of the DC line, sufficient speed to isolate internal faults before the blocking of the converter, sufficient sensitivity and security for a 500-kV system, and sufficient robustness against disturbances.

中文翻译：

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自适应直流故障中断的 VSC-MTDC 允许导频保护

摘要 基于电压源换流器的多端高压直流（VSC-MTDC）系统是一种新技术，与传统直流系统相比具有许多优点。然而，广泛使用的半桥模块化多电平转换器 (MMC) 无法抵御直流故障，除非主保护运行速度足够快以跳闸本地直流断路器。为此，迫切需要开发适用于 VSC-MTDC 的高速保护方案。然而，现场应用中许多先进的保护策略都需要在直流线路的每一端配置故障限流电抗器，这不仅增加了投资，而且对直流线路的动态响应能力产生了负面影响。系统。还，需要进一步解决提高敏感性与确保现有保护计划的选择性之间的两难问题。在这项研究中，基于后向行波和前向行波之间的能量比，提出了一种新的允许导频保护方案。所提出的保护方案只需要来自远端的逻辑信号，避免了数据交换和同步带来的沉重负担。仿真结果表明，所提出的保护具有足够的覆盖范围来覆盖直流线路的整个长度，足够的速度在转换器阻塞之前隔离内部故障，对于 500 kV 系统具有足够的灵敏度和安全性，以及足够的抗干扰鲁棒性. 基于后向行波和前向行波的能量比，提出了一种新的允许导频保护方案。所提出的保护方案只需要来自远端的逻辑信号，避免了数据交换和同步带来的沉重负担。仿真结果表明，所提出的保护具有足够的覆盖范围来覆盖直流线路的整个长度，足够的速度在转换器阻塞之前隔离内部故障，对于 500 kV 系统具有足够的灵敏度和安全性，以及足够的抗干扰鲁棒性. 基于后向行波和前向行波的能量比，提出了一种新的允许导频保护方案。所提出的保护方案只需要来自远端的逻辑信号，避免了数据交换和同步带来的沉重负担。仿真结果表明，所提出的保护具有足够的覆盖范围来覆盖直流线路的整个长度，足够的速度在转换器阻塞之前隔离内部故障，对于 500 kV 系统具有足够的灵敏度和安全性，以及足够的抗干扰鲁棒性. 避免数据交换和同步带来的沉重负担。仿真结果表明，所提出的保护具有足够的覆盖范围来覆盖直流线路的整个长度，足够的速度在转换器阻塞之前隔离内部故障，对于 500 kV 系统具有足够的灵敏度和安全性，以及足够的抗干扰鲁棒性. 避免数据交换和同步带来的沉重负担。仿真结果表明，所提出的保护具有足够的覆盖范围来覆盖直流线路的整个长度，足够的速度在转换器阻塞之前隔离内部故障，对于 500 kV 系统具有足够的灵敏度和安全性，以及足够的抗干扰鲁棒性.