In the last decade, in some countries, the penetration of distributed energy sources has increased significantly. Mostly of the renewable type, these generating units are connected to distribution systems and have been subjected to connection requirements compliant with the historical planning and operating principles of distribution systems, which were designed for passive loads. As people safety is a major concern, the detection of the loss of connection to the main network (loss-of-mains detection) is crucial. Loss-of-mains detection is often performed through the measurement of frequency deviations and triggers generation disconnection to avoid keeping energized isolated networks. However, if applied simultaneously to a large number of units, unique frequency thresholds can jeopardize the security of the whole interconnected system in case of frequency deviations.
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