Browsing by Author "Mykhailenko, Oleksii"

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Advanced Space Vector Modulation with “Fractional” Power Cells
(Elsevier B.V., 2025) Busher, Victor; Shestaka, Anatoliy; Melnikova, Lubov; Kuznetsov, Vitaliy V.; Mykhailenko, Oleksii; Kovalenko, Viktor; Kutyk, Viktor; Osadchyi, Dmytro; Osypenko, Iryna O.; Abdel Gawad, Samer
ENG: The paper develops a model and studies various operating modes of a 5-phase multi-level cascade inverter as part of high-voltage powerful variable-frequency drives (VFD) with the most typical fan load for this type of electric drives. The aim of the work is to test the efficiency of the balanced spatial-vector pulse-width modulation method in a multi-phase high-voltage multi-level inverter in emergency modes by simulating the electric drive in the MATLAB/SIMULINK/Simscape Electrical environment. The paper studies the features of using the balanced spatial-vector pulse-width modulation method in a five-phase frequency converter in normal and emergency modes and, especially, the differences from a three-phase inverter with a similar control principle. The model with a 5-phase synchronous motor from the MATLAB ac8_example.slx database is taken as a basis, which allows us to consider the simulation results reliable. The rules for calculating phase voltages in normal and emergency modes are formulated and the corresponding blocks of the inverter control system model are prepared - a block for calculating basic vectors and a block of spatial vector pulse-width modulation (PWM). The output signals of this block are used for further processing in the modules for controlling power cells with 2- or 3-level PWM. Such a model for a 5-phase electric drive has been built for the first time, which is a scientific novelty of the work. Calculations of transient processes showed the absence of any oscillations, shocks when the system switches from normal to emergency mode and vice versa. That is, the proposed method of balanced spatial vector modulation preserves the symmetry of electromagnetic fields in the engine when individual H-bridges are damaged. It is shown that in normal mode, a 5-phase inverter using the spatial vector modulation method allows increasing the utilization factor of voltage sources by 23.1%. When individual power cells in phases fail, the utilization factor may decrease, but in any case it remains greater than 1. The method ensures compensation for emergency damage even in the event of a short circuit of one or two inverter phases. This significantly increases the service life of the electric drive, which is especially important in critical mechanisms and technological processes, where such complex inverters are actually used. The study found that when using the proposed method in a 5-phase VFD, unlike a 3-phase one, the current balance in the load is disrupted, which leads to increased heating of individual phases of both the motor and the power section of the inverter. The second point of scientific novelty of the work is that in order to reduce this negative effect, it is proposed to improve the algorithm for calculating the output coordinates of the regulator by using the so-called “fractional” power cells with a voltage that is not a multiple of their rated voltage. This leads to a smooth change in phase shifts and asymmetry when individual H-bridges and even one or two phases are damaged. This, in turn, reduces the current imbalance and the corresponding overheating from 2...3 to 12...15%, which gives confidence in the efficiency of using this improvement. It is also important to note that such a change in the control algorithm does not require any changes in the circuit and does not increase the requirements for the computing power of the processors used.
Modeling of Wind Speed Distribution in Urban Environment for the Application of Wind Energy Potential Estimation: Case Study
(UIKTEN, Serbia, 2025) Mykhailenko, Oleksii; Karabut, Nadezhda; Doskoch, Volodymyr; Burtseva, Olena; Kuznetsov, Vitaliy V.; Tsvirkun, Sergij; Kolomits, Hanna
ENG: When designing wind farms, the first stage is always an assessment of the target area wind energy potential. It is necessary to have a mathematical description of the wind speeds occurrence probability at the wind turbines potential location to do this. An analysis of relevant studies shows that the most effective approach to obtaining such dependencies is when the wind speed is taken as a random variable. In this case, wind speed distribution in the target area can be modeled using continuous probability distributions. This article is devoted to determining the typical probability distribution models for representing wind conditions in certain areas of the Dnipropetrovsk oblast (Ukraine), which can be used to estimate expected level of power generation by wind power plants. To obtain the data, a series of wind speed measurements were taken at three locations throughout the year. After that, frequency wind speed distributions with ranges of 0.2, 0.5, and 0.8 m/s were created from the obtained dataset and then approximated by continuous probability distributions. Frequency distributions were modeled by Weibull, Rayleigh, Nakagami, gamma, normal, log-normal, generalized extreme value, Birnbaum-Saunders, Wald and Rice continuous distributions. To determine the parameters of each type probability distribution, which is the most relevant to the frequency distribution, the maximum likelihood estimation method was used. To assess the accuracy of the models, the Pearson test, coefficient of determination and normalized root mean square deviation are used. The probability distributions quality is also evaluated graphically using Q-Q plots. The best fit to wind speed frequency distributions demonstrated by the Weibull probability distributions. A slightly lower accuracy was provided by the normal, Rice and Nakagami distributions than Weibull distribution. But in some cases, these distributions have even smaller error than the last one. Therefore, after detailed analysis and validation, they can also be used. The Rayleigh distribution had the worst accuracy, the Pearson test for it rejected the null hypothesis that the probability distributions correspond to the frequency distributions at all three locations. Additionally, the effect of the frequency distribution wind speed grouping range on the quality of maximum likelihood estimation of continuous distribution parameters was analyzed. It showed that the approximation accuracy decreases with increasing range.