AUTOMATIC CONTROL SYSTEM OF THE OPERATION MODES OF THE POWER DISTRIBUTION NETWORK WITH SOLAR POWER PLANTS UNDER UNBALANCED LOAD

Abstract

The use of renewable energy sources is the most priority direction of Ukraine's energy policy, which is aimed at saving traditional fuel and energy resources, improving the environment and preventing climate change. Taking into account the climatic and geographical features of the territory of Ukraine, it is considered economically feasible to use generating units based on solar and wind energy. At the moment, solar power plants (SPPs) have become the most widespread in Ukraine, the total installed capacity of which is 7,751 MW as of 2022, which is 6% more than in the previous year. The integration of SPPs into power distribution networks (PDN) with their subsequent parallel operation leads to the transition from passive centralized power supply to active decentralized power supply. Under the condition of commensurate power of the electric network and SPP, there is a change in the operation mode of the first, which in the minimum load modes leads to an increase in the voltage level on the buses connecting the SPP to the PDN. Thus, there is a need for research and development of technological solutions aimed at optimizing the integration of grid solar power plants in order to improve the quality of electric energy in distribution systems with a nominal voltage of 10 kV. One of these solutions is the improvement of the automatic control system (ACS) of the generation of active power of the SPP, which will allow controlling the amount of voltage deviation at the point of connection to the electrical network, by limiting the power to specified settings. With this approach, the value of voltage deviation will always be within acceptable limits. However, this kind of control does not take into account the ability of SPP inverters to influence voltage unbalance and reactive power modes. Modern PDNs are characterized by considerable heterogeneity. The presence of a large number of powerful singlephase consumers, as well as three-phase consumers that do not work at the same time, is one of the reasons for voltage unbalance in 10 kV networks. Taking this into account, the task of improving the ACS with modes of operation of PDN with SPP, the implementation of which will allow to achieve a simultaneous reduction in the level of steady-state voltage deviation, the level of voltage unbalance, and the level of reactive power consumption under the condition of the maximum possible value of electricity generation, is relevant.