This paper presents a method for refining the forecast schedule of renewable energy sources (RES) generation by its intraday adjustment and investigates the measures for reserving RES with unstable generation in electric power systems (EPSs). Owing to the dependence of electricity generation by solar and wind power plants (PV and WPPs, respectively) on natural conditions, problems arise with their contribution to the process of balancing the power system. Therefore, the EPS is obliged to keep a power reserve to compensate for deviations in RES from the planned generation amount. A system-wide reserve (mainly the shunting capacity of thermal and hydroelectric power plants) is used first, followed by other means of power reserve: electrochemical, hydrogen, or biogas plants. To analyze the technical and economic efficiency of certain backup means, mathematical models based on the theory of similarity and the criterion method were developed. This method is preferred because it provides the ability to compare different methods of backing up RES generation with each other, assess their proportionality, and determine the sensitivity of costs to the capacity of backup methods with minimal available initial information. Criterion models have been formed that allow us to build dependencies of the costs of backup means for unstable RES generation on the capacity of the backup means. It is shown that, according to the results of the analysis of various methods and means of RES backup, hydrogen technologies are relatively the most effective. The results of the analysis in relative units can be clarified if the current and near-term price indicators are known.

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

According to the new Law of Electricity Market of Ukraine, photoelectric stations will be obliged to declare their generation graphic one day ahead. Proceeding from this, the task of hourly prediction of generation of PV arises a day ahead. Since such a graph significantly depends on the change of meteorological parameters, in the work it was investigated which of them most influence generation. On the basis of the analysis it was determined that this is solar radiation, cloudiness, humidity, wind speed and temperature. The determined meteorological parameters included the construction of the neural network for forecast the hourly generation of PV on day ahead. Neural networks which proposed that is capable of predicting the generation of photovoltaic stations with a fairly high accuracy.

This research demonstrates the possibility and expediency of forming local electric energy systems (LEESs) based on renewable sources of energy (RSE) as balancing groups in the electric power system (EPS), which can maintain efficiency and provide power supply to consumers in an autonomous mode. The LEES is a part of the EPS of thermal and nuclear power plants and is considered as a separate balancing group. LEESs are designed in such a way that they can operate autonomously in both normal and extreme conditions in the EPS. The sources of electricity in LEESs are small hydroelectric power plants (SHPPs), photovoltaic power plants (PVPPs), and wind power plants (WPPs), whose electricity generation is unstable due to dependence on natural conditions. Therefore, the structure of a LEES with RSE includes an energy storage system with reserves sufficient to compensate for the unstable generation and balancing of the mode. LEESs can differ significantly in terms of key technical and economic indicators (power supply reliability, power losses, and power quality), and therefore, it is necessary to choose the optimal one. It is not advisable to optimize the quality of power supply in a LEES by individual indicators, as improvement of one indicator may lead to deterioration of another. The functional readiness of a LEES should be assessed by the quality of operation, which depends on reliability, power losses, and power quality. To simplify the task of assessing the quality of operation, which is a vector optimization problem, a method for determining the integral indicator as a number that characterizes the LEES and reflects the compromise between the values of reliability, power losses, and power quality has been developed. The integral indicator of the functioning of complex systems is based on a combination of the theory of Markov processes and the criterion method of similarity theory. The value of the integral indicator of the quality of operation of the LEES allows for comparing different variants of power transmission and distribution systems without determining individual components of technical and economic indicators—reliability, power losses, and power quality. The offered integral indicator of the quality of functioning of a LEES with RSE corresponds to the general requirements for such indicators. It reflects the actual operating conditions; allows for assessing the efficiency, quality, and optimality of power supply systems; and can be easily decomposed into partial indicators.

Mathematical model for operation quality assessment of electric grid with renewable sources of energy is suggested, the given model takes into consideration balance reliability and voltage quality. The assessment of renewable sources of electric energy impact on functional preparedness of distributed electric grid to provide reliable and quality energy supply was performed, applying the developed model.

Greater part of renewable energy sources is represented by solar electric stations (SES). Their operation mode depends on natural conditions of the region, where they are located. That is why the problem of RES stability estimation is important in the problem of covering the daily schedule of energy consumption. One of the aims of the research is to evaluate the probability of providing the consumption schedule by means of corresponding source on the base of statistic data. In this paper, the algorithm determination of stability covering load demand their own generation of renewable energy, particularly solar power, was proposed. On the basis of this indicator the method of determining the optimum by criterion of minimum reduced cost, power, which should provide a source of reserve to maintain an appropriate level of reliability in carrying the local electrical system. This method, based on the evaluation of stability data for generating renewable energy sources, including solar power, the problem of covering a given load demand and its impact on the number electricity.