Thanks to the development of technology, the presence of electric vehicles (EVs) on the roads is no longer a purely theoretical issue. Also in Poland, electric cars are already visible on the streets, and charging stations (EVCS) are increasingly being installed near newly emerging buildings and housing estates. The article attempts to determine to what extent the use of electric cars will affect the demand for power and energy in the Polish electric power system (PEPS). The basis for PEPS modernization plans should be a detailed analysis of the technical adequacy of all its subsystems: generation, transmission and distribution, on the basis of which it will be possible to assess the potential impact of EVCS infrastructure operation on the Polish electric power system. This publication presents an example of such analysis for the distribution sub- sector, most exposed to potential negative interactions with the future, extensive infrastructure of EVCS.

The energy transition toward low-carbon electricity systems has resulted in a steady increase in RESs. The expansion of RESs has been accompanied by a growing number of energy storage systems (ESSs) that smooth the demand curve or improve power quality. However, in order to investigate ESS benefits, it is necessary to determine their reliability. This article proposes a four-state reliability model of a battery ESS operating with a PV system for low-voltage grid end users: households and offices. The model assumes an integration scenario of an ESS and a PV system to maximize autoconsumption and determine generation reliability related to energy availability. The paper uses a simulation approach and proposes many variants of power source and storage capacity. Formulas to calculate the reliability parameters—the intensity of transition $\lambda$, resident time $T_i$, or stationary probabilities—are provided. The results show that increasing the BESS capacity above 80% of daily energy consumption does not improve the availability probability, but it may lead to an unnecessary cost increase; doubling the PV system capacity results in a decrease in the unavailability probability by almost half. The analysis of the results by season shows that it is impossible to achieve a high level of BESS reliability in winter in temperate climates.

In this paper we describe the methodology of determining the reliability indices for power generating subsystem. We analyse then influence of the considered wind power plant reliability modelling on system reliability. The proposed reliability model of wind power plant is two-state model as compromise between calculation time and accuracy. We have found an empirical relationship between the power system reliability index LOLE (Loss of Load Expectation) and reserve capacity margin for a given wind share. This allowed us to estimate the required minimal reserve capacity margin for a given level of power system security and for a known structure of system installed capacity.