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

分布式发电机组(DG)每年都集成在公共电网中。特别支持使用可再生能源的DGS。因此，许多由化石能源运营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、控制备用和电能质量维护，都必须由较小的分布式电源来承担。因此，电网的性质从集中组织转变为分散控制任务的分散系统。公共电网的这种转换导致意外电气孤岛的频率增加，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。无意岛是一种子电网，在与上游电网断开后仍保持通电状态，即使断电状态也是如此。以往的调查表明，无意岛领域的许多研究仍有待完成。一方面，必须对从集成电网到电气孤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。到目前为止，RLC并联电路被认为是最坏的负载条件，与电网中的实际电气负载相比，证明是不关键的。以前的假设，即在RLC载荷下对DG行为的调查就足够了，这一假设可能会被驳斥。到目前为止，该项目已经可以对低压电网的负荷行为进行确定和分析。下一步，重要的是将研究扩展到中压配电网和三相逆变器测量。过去几年在各种实际配电网中发生的意外岛屿证实，这个问题已经相关。同时，在处理这一现象方面缺乏基本的知识和经验。分布式发电是分布式发电的持续一体化所追求的方法，即使在上游电网停运期间，也有可能安全地提供子电网的能源。为了实现这一点，在蜂窝电网运行模式的框架内运行意向岛的概念必须在电力系统的重组过程中及早整合。因此，在这个项目中，应该研究利用电力存储和概念来选择性地调整意向岛上的电力负荷的可能性。这种扩展的孤岛概念必须确保在可能发生重大停电的情况下，大型子电网的持续能源供应。将设计一种对子电网的智能控制，使其能够安全地再同步到上游电网，而不会出现停电时间。

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.