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Electrical power systems are changing their traditional structure, which was based on a little number of large generating power plants placed at great distances from loads by new models that tend to split the big production nodes in many smaller ones. The set of small groups which are located close to consumers and provide safe and quality energy is called distributed generation (DG). The proximity of the sources to the loads reduces losses associated with transportation and increases overall system efficiency. DG also favors the inclusion of renewable energy sources in isolated electrical systems or remote microgrids, because they can be installed where the natural resource is located. In both cases, as weak grids unable to get help from other nearby networks, it is essential to ensure appropriate behavior of DG sources to guarantee power system safety and stability. The grid codes sets out the technical requirements to be fulfilled for the sources connected in these electrical networks. In technical literature it is rather easy to find and compare grid codes for interconnected electrical systems. However, the existing literature is incomplete and sparse regarding isolated electrical systems and this happens due to the difficulties inherent in the pursuit of codes. Some countries have developed their own legislation only for their island territory (as Spain or France), others apply the same set of rules as in mainland, another group of island countries have elaborated a complete grid code for all generating sources and some others lack specific regulation. This paper aims to make a complete review of the state of the art in grid codes applicable to isolated systems, setting the comparison between them and defining the guidelines predictably followed by the upcoming regulations in these particular systems.

The aim of this paper is to analyze behavior of isolated power system in case of short-term interruptions that is applied on one of the loads fed from the grid. Developed mathematical model of the system under consideration involves gen-set, prime mover and synchronous generator, and induction motors as active consumers. The aim of this paper is to analyse effect of short-term interruptions from the point of view of source and loads. Analysis includes connecting another load while the transition regime is not terminated.

The aim of this paper is to analyze dynamics of isolated electrical grid during short term interruptions. The effect of short term interruptions of the power supply on the characteristic values of synchronous generator in autonomous operation is analyzed. Dynamical loads (two induction motors), are connecting to the grid. Short-term interruptions that occur in different moments allow analyze of this phenomenon on the generator and on the other uninterrupted motor.