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

分布式发电机组（DG）每年都被整合到公共电网中。特别支持使用可再生能源的DG。因此，许多由化石能源运营的大型发电厂变得无利可图，不得不关闭。有功功率的产生以及许多基本的系统服务，如无功功率供应，控制储备和电能质量的维护必须由较小的DG接管。因此，电网的特征从集中组织的系统变为具有分布式控制任务的分散系统。公共电网的这种转换会导致无意的电气孤岛出现的频率越来越高，这可能导致不受控制的持续能源供应，从而产生潜在的危险。非故意孤岛是一个子电网，它在与上游电网断开连接后保持通电状态，即使断开连接的目的是断电状态。以前的调查表明，在非故意孤岛领域的大量研究仍然需要做。一方面，必须对从综合电网到电气岛以及向后的过渡过程进行基础研究。另一方面，必须考虑不同DG之间的相互作用。RLC并联电路，这是假设为最坏情况下的负载条件，到目前为止，被证明是不关键的相比，在电网中的真实的电力负载。前面的假设，即RLC负载的DG行为的调查是足够的，可以反驳。到目前为止，该项目可以确定和分析低压电网的负荷行为。下一步，重要的是将调查扩展到中压配电网和三相逆变器的测量。在过去几年中，在各种实际配电网中出现的无意孤岛证实了这个问题已经存在。与此同时，在处理这一现象的基本知识和经验缺乏。分布式发电的方法，这是追求的持续集成的DG，有一个安全的能源供应的子电网，即使在上游电网停电的潜力。为了实现这一点，必须在电力系统重组期间尽早整合在蜂窝电网运行模式框架内的有意孤岛运行概念。因此，在本项目中，应研究利用电力储存和概念选择性调整有意岛屿中的电力负荷的可能性。这种扩展的孤岛概念必须确保大型子电网在可能发生重大停电的情况下持续提供能源。将设计一个子电网的智能控制，它可以在没有停机时间的情况下安全地向上游电网供电。

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.