Nowadays there is an increasing demand even on the distribution network level for to the distributed generation systems using renewable energies. The better use of renewable energy sources, the increasing penetration of distributed generators and the importance of energy supply’s continuity require using more and more „smart” devices on the network. A possible solution for these requirement is the microgrid. The microgrid is a smaller, definite part of distribution network, which contain distributed generators, customers and energy storage units. It is connected to the public network via point of common coupling (PCC), which could be switched off in certain cases, e.g. in case of faults of public network. In this case the microgrid is working autonomously in „islanded” mode and it could supply customers: thus, the microgrid is a self-sustainable system. For the optimal operation it is essential to use control system, which could modify the operation of local devices in both grid-connected and islanded mode.
One of possible analysing method of microgrid system is the simulation of the microgrid. The NTS simulator software of the Astron Informatic Ltd. is very suitable for this reason. The task of my diploma thesis is to build a small, simplified microgrid model to show the basics of microgrid’s operation. Firs I learnt the simulating environment, later I searched for literatures describing the operation logic of microgrids, the natures of components and controlling possibilities. Using this I prepared a compact but simplified small AC microgrid system in the NTS simulating environment. The model contains the following: (i) models of customers, generators and storage units; (ii) frequency-model; (iii) control algorithm; (iv) load-flow calculation algorithm. The model represents a low-voltage transformer section with simple frequency-model. The control logic of the simulated takes into account the power increasing and decreasing of devices, and it handles the customers’ and generators’ priorities as well as the State Of Charge (SOC) of the storage unit.