The short circuit response of a voltage source converter (VSC) under grid unbalanced faults mainly depends on the design of its control system. Due to the limited semiconductor overload capability, the short circuit current contributed by a VSC should be restricted within the limit for each phase. This might bring up challenges to the protection system of a converter-dominated power system. This paper derives a generic converter peak current limitation method for three different VSC control strategies. The impact of the control strategies and the combined impact of a VSC with a synchronous condenser on distance protection are evaluated using a commercial relay through hardware-in-the-loop (HIL) tests. Based on the test results, we propose to avoid using constant reactive power control strategy. It poses an adverse impact on the reliability and speed of distance protection regardless of the presence of a synchronous condenser at the point of common coupling, while constant active power and balanced current control strategies favor the performances of distance protection.

中文翻译：

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不平衡故障下VSC控制策略和并入同步电容器对距离保护的影响

电网不平衡故障下电压源换流器（VSC）的短路响应主要取决于其控制系统的设计。由于半导体过载能力有限，VSC 贡献的短路电流应限制在每相的限制范围内。这可能会给变流器主导的电力系统的保护系统带来挑战。本文针对三种不同的 VSC 控制策略推导出通用转换器峰值电流限制方法。使用商用继电器通过硬件在环 (HIL) 测试来评估控制策略的影响以及带有同步电容器的 VSC 对距离保护的综合影响。根据测试结果，我们建议避免使用恒定无功功率控制策略。