This paper proposes hybrid islanding detection for inverter-based distributed generation (DG) units. Conventionally, passive islanding detection methods may fail when power mismatches are nearly zero. Also, the difficulty of setting threshold is another common problem. To overcome this drawback, a new procedure for islanding detection is proposed based on the combination of the rate of change of voltage (ROCOV) and the rate of change of active power (ROCOAP). The ROCOAP is only activated when the islanding condition is suspected by ROCOV. When the power mismatch is negligible, some high-impedance fault or non-islanding events occur, the proposed method can identify islanding, thus presenting a combination of advantages of each passive/active method. Therefore, it is useful to appropriately detect islanding situation in all-inclusive of scenarios. Consequently, the proposed method under several conditions, such as pulsating loads, pre-energized transformers have been considered. To illustrate the effectiveness of the proposed approach, various tests such as UL1741 have been investigated. Comparison analysis shows that the suggested method is more acceptable and the NDZ is reduced significantly. In addition, proper performance even for small power mismatch is illustrated by presence of variety of non-islanding events and improvement of power quality is achieved in comparison active method.

中文翻译：

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基于电压和有功功率变化率的多逆变器系统混合孤岛检测方法

本文提出了基于逆变器的分布式发电 (DG) 单元的混合孤岛检测。通常，当功率失配几乎为零时，无源孤岛检测方法可能会失败。此外，设置阈值的难度是另一个常见问题。为了克服这个缺点，提出了一种基于电压变化率 (ROCOV) 和有功功率变化率 (ROCOAP) 组合的孤岛检测新程序。ROCOAP 仅在 ROCOV 怀疑孤岛情况时激活。当功率失配可以忽略不计，一些高阻抗故障或非孤岛事件发生时，所提出的方法可以识别孤岛，从而呈现出每种被动/主动方法的优势组合。因此，在所有场景中适当地检测孤岛情况是有用的。因此，已考虑在多种条件下提出的方法，例如脉动负载、预通电变压器。为了说明所提出方法的有效性，已经研究了各种测试，例如 UL1741。对比分析表明，建议的方法更容易接受，NDZ显着降低。此外，通过各种非孤岛事件的存在说明了即使对于小功率失配也具有适当的性能，并且在比较有源方法中实现了电能质量的改善。对比分析表明，建议的方法更容易接受，NDZ显着降低。此外，通过各种非孤岛事件的存在说明了即使对于小功率失配也具有适当的性能，并且在比较有源方法中实现了电能质量的改善。对比分析表明，建议的方法更容易接受，NDZ显着降低。此外，通过各种非孤岛事件的存在说明了即使对于小功率失配也具有适当的性能，并且在比较有源方法中实现了电能质量的改善。