The Least-Cost Optimization of PV-Station DC/AC Equipment Using Battery Energy Storage System

The auction allocation of state support quotas for renewable generation implementation that will change the existing incentive for their development by providing “green” tariffs to producers is based on competitive selection of the power plant projects with the least cost of electricity generation. The competitive advantage of solar photovoltaic power plant (PV stations) projects can be done by deciding what kind of equipment can provide the minimum cost of electricity generation during the period of operation. In the article, there is improvement of non-linear mathematical least-cost optimization model of the structure of PV-station equipment using DC coupled battery energy storage system (BESS) to store the excess electricity of photovoltaic modules (PV modules), which is lost on inverters when they are overloaded during the hours of the highest intensity of solar radiation. The article presents the modelling results of overall operation of PV station with fixed power of PV modules, as well as determines optimal power of inverter equipment and battery capacity. The model calculations have shown that when the DC equipment costs of the PV station are reduced by almost 62 % and DC equipment costs of BESS are reduced by 86.7 % of the actual value in 2020 at the power of 10 MW PV modules, the optimal power of inverter equipment decreases from 7.08 to 6.29 MW, and the storage capacity increases from 0.22 to 2.51 MWh. The use of BESS allows accumulating the amount of electricity produced by PV modules, which is lost with limitation on inverters, while the cost of their joint electricity production is decreased by 0.42 %.