Abstract In order to maximize the utility of renewable energy resources, long-distance power transmission lines are essentially required. To accomplish this purpose, the voltage-source-converter (VSC) based high voltage direct current (HVDC) transmission is considered an attractive option. However, due to DC-link capacitors and their discharge currents, the VSC-HVDC based transmission networks are more vulnerable to short circuit faults. The direct current circuit-breakers (DCCBs) are considered a reliable option to protect the transmission line against short circuit faults. The DCCBs with increased voltage rating and fault-current interruption capability are still considered a gigantic problem. The capacity issues of DCCBs can be alleviated using some external circuits to reduce the intensity of fault-current. This paper introduces an external fault-current limiting circuit (FCLC), which is non-superconducting in nature, and it consists of power electronics-based bidirectional switches, current limiting inductor, and power dissipating resistor. This circuit is placed in series with a DCCB, to escalate the response time in the advent of fault, to restrict the maximum value of fault-current, and to reduce the stresses on energy absorption components in DCCB. The circuit is activated only when fault-current limitation operation is required, thereby, the proposed FCLC has zero power-loss in the nonoperational state, and has no influence on the steady-state performance of the system. Furthermore, regarding FCLC, the detailed working principle, parametric analysis, and rigorous evaluation of performance are accomplished in this paper. The theoretical concepts are validated using a three-terminal VSC-HVDC model and equivalent circuit analysis, in PSCAD/EMTDC simulation-based environment. The results of FCLC are compared with other solutions in the literature. The comparison of results concludes that the proposed FCLC own better characteristics, in terms of control features, fault clearing time, and power losses.

中文翻译：

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一种改进的 VSC-HVDC 输电系统故障限流电路

摘要 为了最大限度地利用可再生能源，本质上需要长距离输电线路。为了实现这一目的，基于电压源转换器 (VSC) 的高压直流 (HVDC) 传输被认为是一种有吸引力的选择。然而，由于直流母线电容器及其放电电流，基于 VSC-HVDC 的输电网络更容易出现短路故障。直流断路器 (DCCB) 被认为是保护输电线路免受短路故障的可靠选择。具有更高额定电压和故障电流中断能力的 DCCB 仍然被认为是一个巨大的问题。DCCB 的容量问题可以通过使用一些外部电路来降低故障电流强度来缓解。本文介绍了一种非超导的外部故障限流电路（FCLC），它由基于电力电子的双向开关、限流电感和功率耗散电阻组成。该电路与 DCCB 串联，以提高故障发生时的响应时间，限制故障电流的最大值，并降低 DCCB 中能量吸收组件的应力。该电路仅在需要进行故障限流操作时才被激活，因此，所提出的 FCLC 在非操作状态下具有零功耗，并且对系统的稳态性能没有影响。此外，对于FCLC，本文还完成了详细的工作原理、参数分析和严格的性能评估。在基于 PSCAD/EMTDC 仿真的环境中，使用三端 VSC-HVDC 模型和等效电路分析验证了理论概念。FCLC 的结果与文献中的其他解决方案进行了比较。结果的比较得出结论，所提出的 FCLC 在控制特性、故障清除时间和功率损耗方面具有更好的特性。