The thesis addresses the influence of self-consumption from solar power stations and battery systems on voltage, power flow, and losses in the distribution network.
The model discussed consists of a 110 kV busbar in RTP Sežana, a power transformer 110/20 kV, a medium voltage network with the thoroughly modelled object medium voltage feeder DV Divača, which powers 11 transformer stations. One of these is TP Merče, where we established a complete low voltage network. This network is analysed in the present paper. Real measurements of 15 minute average values of consumer load diagrams, production of the solar plant located in Merče, and the voltage at individual points in the network for the year 2015 were used. The data was provided by the operator of the network.
The adequacy of the model was established by the validation with real 15 minute average voltage values at the secondary side of transformer at the transformer station Merče, in the year 2015.
Based on the known fact of the increased usage of renewable resources, we set two scenarios. The first shows the rise of the usage of solar power stations at consumers in low voltage network to 30 percent, while the second anticipates the rise to 60 percent. In both scenarios, we compared tree situations – operation of the distribution network discussed in the present state without sources, with installed solar power plants at the chosen clients, and with added battery systems at the chosen clients with solar power plants.
The results of the first scenario show considerable rises of voltage and load flows because of the production by solar power stations. They do not exceed the approved values. Positive effects of battery systems can be observed; however, they do not eliminate the high extreme values. In the field of losses, there are no bigger derogations. In the second scenario, the losses are highly increased, the power flows in the direction of the medium voltage network exceed the thermic limit of the transformer, and voltages also exceed the approved values. The influence of battery systems is more distinct than in scenario one; however, battery systems do not eliminate the high extreme values. The main reasons for this are battery systems that are dimensioned for the purpose of self-consumption, and their way of operation. If the batteries were planned as a system service, they could be operated to receive electric energy from the network independently of the attached solar power plan and this only in the case of extreme unwanted voltage values and/or power flow (eliminating peaks) or some middle possibility. Situation three according to scenario one proved to be the best possible combination.