The effects of solar power plants on the distribution networks and providing voltage regulation by Volt / Var / Demand control

Volt / VAR / Demand control is a versatile function affected by consumer points, transmission, production and network operation changes in active distribution networks. On load tap changers (LTC), voltage regulators, capacitors and reactors are the main elements for regulating voltage changes in such distribution network. The voltage level changes using these network elements affect the power quality and the active and reactive consumption on the subscriber side. The power factor on the subscriber side also changes as reactive loads affecting system voltage more than active loads. These changes affect the power flows in the distribution network as well as technical losses and invoices. First off, the effect of solar power plants on the distribution network was investigated by using simulation study in this thesis. According to the load status of the solar power plants on the feeder effects on the distribution network events, such as voltage increases and current carrying capacities on the lines were examined with realistic grid simulation. Simulation study was carried out, on Kozluca feeder from Burdur TEİAŞ substation with DIgSILENT PF. When all these power plants with the connection license of 19.5 MW are activated in the Kozluca feeder the network grid problems were examined and the solution methods have been proposed. Remote communication system (SCADA) was installed to 1 Solar Plant on the Burdur TM Kozluca substation and control was provided by the centralized software for in order to observe the results of the simulation outputs in the field and to see the effects of the proposed methods. All inverters in this plant were operated in different reactive power sets with a datalogger and the realizations in the feeder were monitored with the help of the class A quality recorder in the feeder head. In the main software, the algorithm which has been able to control the desired reactive power in the feeder and to keep it within the power quality indicators required by EPDK, has been run. In order to observe the results of the simulation outputs in the field and to see the effects of the proposed methods on the feeder, by designing a new control algorithm for reactive power control, an alternative method has been proposed for voltage regulation problems in the distribution network and the existing standard applications. As a method, the output parameters of the inverters in solar power plants were used, and an automatic decision making system was used to control the most suitable voltage or active / reactive power values. As a result of the study, it was seen that central and local control options would be presented at the same time in solar power plants and distribution network, and there could be a control that could move from a single interface which would have control capability on the basis of inverter. Since the existing solar power plants in the network are used for the regulation of the volts / VAR, the need of additional reactor, capacitor, OLTC installation on the feeder line will be eliminated and the investment costs which is spend by distribution companies for reactive power control and voltage regulation can be reduced.