Reliable detection of electrical islands. Base for a cellular grid operation mode.

分布式发电机组（DG）每年都被纳入公共电网。使用可再生能源的dg尤其受到支持。因此，许多使用化石能源的大型发电厂正变得无利可图，不得不关闭。有功发电以及许多基本的系统服务，如无功供电、控制储备和电能质量维护，必须由较小的dg接管。因此，电网的特点从一个集中组织的系统转变为一个分散控制任务的系统。公共电网的这种转换导致无意的电力孤岛的频率增加，这可能导致不受控制的、因此具有潜在危险的持续能源供应。无意孤岛是指在与上游电网断开连接后仍保持通电的子电网，即使断开连接的目的是处于断电状态。以往的调查表明，在非故意岛屿领域还有很多研究需要做。一方面，必须对从综合电网到电力孤岛再到电力孤岛的过渡过程进行基础性研究。另一方面，必须考虑不同dg之间的互动。RLC并联电路假定为最坏负荷状态，与电网实际负荷相比，RLC并联电路是不临界的。先前的假设，即对rlc载荷下DG行为的研究是充分的，可以被反驳。目前在工程中可以确定和分析低压电网的负荷行为。下一步，重要的是将研究扩展到中压配电网和三相逆变器的测量。在过去几年中，各种实际配电网中出现的无意孤岛证实了这个问题已经相关。同时，缺乏处理这一现象的基本知识和经验。分布式发电是dg持续整合所追求的方法，即使在上游电网中断时，也有可能为子电网提供安全的能源供应。为了实现这一目标，必须在电力系统重组的早期整合蜂窝网格操作模式框架中有意岛屿操作的概念。因此，在这个项目中，将研究利用电力储存和概念在一个有意岛屿中选择性地调整电力负荷的可能性。这种扩展的孤岛概念必须确保在潜在的重大停电情况下，大型子电网的持续能源供应。将设计一种智能控制子电网，使其能够安全地与上游电网重新同步，而不会中断时间。

Distributed generation units (DG) are integrated in the public electrical grid each year. DGs, which use renewable energy sources, are especially supported. Therefore, many large-scale power plants, which are operated by fossil energy sources, are becoming unprofitable and have to be closed down. The generation of active power as well as many essential system services like reactive power supply, control reserve and maintenance of power quality have to be taken over by smaller DGs. Thereby, the character of the electrical grid changes from a centrally organized to a decentral system with distributed control tasks. This conversion of the public electrical grid causes an increasing frequency of unintentional electrical islands, which can lead to uncontrolled, and therefore potentially dangerous, continued energy supply. An unintentional island is a sub-grid, which stays energized after disconnection from the upstream grid, even if a de-energized state was the purpose of the disconnection.Previous investigations show that a lot of research in the field of unintentional islands has still to be done. On the one hand, fundamental investigations on the transition processes from integrated grid to electrical island and backwards have to be executed. On the other hand, interactions between different DGs have to be considered. The RLC parallel circuit, which was assumed as worst-case load condition so far, proved to be uncritical in comparison to the real electrical load in the grid. The previous assumption, that an investigation of DG behavior with RLC-loads is sufficient could be refuted. The load behavior of low-voltage grids could be determined and analyzed in the project so far. In the next step, it is important to extend the investigation to medium-voltage distribution grids and measurements with 3 phase inverters. The occurrence of unintentional islands in various actual distribution grids in the last years confirms that the problem is already relevant. At the same time, basic knowledge and experience in handling of this phenomenon are lacking.The approach of distributed generation of energy, which is pursued by the continuing integra-tion of DGs, has the potential of a safe energy supply of sub-grids even during outages of the upstream grid. To make this possible, concepts for the operation of intentional islands in the framework of a cellular grid operation mode have to be integrated early during the reorgani-zation of the electrical system. Therefore, in this project the possibility to utilize electrical storages and concepts for a selective adjustment of electrical loads in an intentional island shall be investigated. This extended islanding concept has to ensure a continued energy supply of large sub-grids in case of potential major outages. An intelligent control of the sub-grids, which enables a safe resynchronization to the upstream grid without outage times, will be designed.