Dynamic Response of a Group of Synchronous Generators following Disturbances in Distribution Grid

Article history: Received: 22.10.2014. Received in revised form: 13.12.2015. Accepted: 14.12.2015. The connection of distributed sources and their impact on distribution grid has been the subject of intensive research in the last two decades. Creating a favorable environment for the production of electrical energy from renewable energy sources in many countries around the world made an evident increase in electrical energy production from renewable sources. Connecting these generators to distribution grid is not always an easy task, and often, in cases of inadequate analysis and poor choice of ways of connecting these sources, can have a negative impact on the quality of electrical energy in local distribution grids. In this paper, using a realistic test system, the focus of research is to identify the behavior of group synchronous generators connected to the medium-voltage distribution grid in "cascade" manner. The selected test system presents the real power distribution system of the Municipality of Gornji Vakuf-Uskoplje, to which six synchronous generators are connected at the moment. Analyses results of the work of this power distribution system in the previous period indicate that there have been significant changes in the existing distribution grid (significant change in voltage, increased losses, etc.) after these generators were connected. Dynamic simulations are conducted on the basis of the appropriate mathematical models, and the response of the generators and changes in the voltage value in the distribution grid were simulated for several types of disturbances. The results show that generators remain in synchronism while tested on selected simulated disturbances, where the oscillations of the generator rotor disappear over a period of several seconds. Also, the changes of voltage value in distribution grids for simulated disturbances are within the permitted limits.