Article citation info: IntroductionFor hundreds of years, the people's need for mobility has contributed to the development of various types of vehicles, which were usually powered by draught animals or humans. However, rapid industrial development in the 19 th century resulted in numerous solutions, which used mechanical drives powered mainly by heating fuels. Initially, these were steam vehicles, and later on, the whole range of various internal combustion engines was developed. The vehicle solutions powered by electric engines also appeared during that period, but electric drive systems were hardly used in vehicles because of limited abilities to store electric energy in mobile systems. For this reason, the 20 th century is the period dominated by vehicles powered by heating fuels [16].However, the use of non-renewable energy sources has this one obvious disadvantage that such sources someday will be exhausted. For this reason, wind power plants and photovoltaic panels appear at single-family houses, wind and photovoltaic farms are built on fields and almost all well-known companies that manufacture cars boast with the offered electric and hybrid ecological vehicles [5,16,19,21]. In comparison with internal combustion engine vehicles, they have many advantages -they do not emit substances detrimental to the environment, are much more efficient (their efficiency exceeds 90%, while internal combustion engine vehicles are characterised by the efficiency ranging between 20% and 30%), their construction is much simpler and cheaper to operate and -what is also important -they can regenerate energy during the braking process [16,21].Not only do the electric vehicles become more and more popular for ecological reasons, but also as a consequence of the technological development of systems used for energy storing. The recent years mark the appearance of the whole range of various kind of batteries whose parameters allow their use in numerous mobile systems, including cars. Unfortunately many of these solutions are much more expensive than popular lead-acid batteries. Additionally, modern batteries often require the application of systems that control their performance (values and distribution of voltages and currents on the respective cells and quite importantly, also the temperature). Failure to observe the limit parameters may lead to their premature aging, and also to a dangerous fire. For this reason, and also because of their low price, lead-acid batteries, whose construction technology is also subject to continuous improvement, are still used. Owing to this, they become more durable and resistant to operating conditions that deviate from nominal operating conditions [16]. Unfortunately, the main disadvantage of the lead-acid batteries is the significant impact of high currents on their life. So far, the solution for this problem included just an increase the number of cells (total capacity), however, in the case of the mobile solutions, this is related to a cumbersome increase in weight. Another solution is the u...

An important issue in the correct operation of the power system is the reliability of the electricity supply from generation systems. This particular problem especially concerns renewable sources, the output power of which is variable over time and additionally has a stochastic character. The solution used in the work to improve the reliability indicators of wind farm sources is the partial stabilization of their output power achieved through cooperation with the kinetic energy storage. Excessive increase in storage capacity is associated with a large increase in investment and operating costs. It is therefore important to determine the minimum storage capacity required to maintain the accepted criteria for the reliability of energy supply. In this paper, a population meta-heuristics algorithm was used for this purpose. The obtained results confirm the possibility of limiting the energy capacity of the flywheels, they also indicate its non-linear character as a function of selected parameters of the reliability of energy supplies from wind farms.

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The paper presents issues of optimisation of a wind power plant–energy storage system (WPP-ESS) arrangement operating in a specific geographical location. An algorithm was developed to minimise the unit discounted cost of electricity generation in a system containing a wind power plant and flywheel energy storage. In order to carry out the task, population heuristics of the genetic algorithm were used with modifications introduced by the author (taking into account the coefficient of variation of the generation in the quasi-static term of the penalty and the selection method). The set of inequality restrictions related to the technical parameters of turbines and energy storage and the parameters of energy storage management has been taken into account with the application of the Powell–Skolnick penalty function (Michalewicz modification). The results of sample optimisation calculations for two wind power plants of 2 MW were presented. The effects achieved in the process of optimisation were described—especially the influence of the parameters of the energy storage management system on the unit cost of electricity generation. The use of a system with higher unit costs of energy generation compared to independently operating wind turbines was justified in the context of improving the conditions of compatibility with the power system—the strategy belongs to a power firming group.

Abstract. The paper presents the methodology of minimisation of the unit cost of production of energy generated in the hybrid system compatible with the lead-acid battery, and used to power a load with the known daily load curve. For this purpose, the objective function in the form of the LCOE and the genetic algorithm method were used. Simulation tests for three types of load with set daily load characteristics were performed. By taking advantage of the legal regulations applicable in the territory of Poland, regarding the energy storing in the power system, the optimal structure of the prosumer solar-wind system including the lead-acid battery, which meets the condition of maximum rated power, was established. An assumption was made that the whole solar energy supplied to the load would be generated in the optimised system.