СТАН ТА ТЕНДЕНЦІЇ РОЗВИТКУ СИСТЕМИ ЕНЕРГОЗАБЕЗПЕЧЕННЯ В УКРАЇНІ

The article discusses contemporary issues of ensuring energy security in Ukraine. A brief overview on the modern energy system which comprises power plants of different types, electrical and thermal networks operating in the manufacturing sector, in transmission and distribution of electrical and thermal energy. The study considers the following types of power plants in the energy system of Ukraine: nuclear, thermal, hydroelectric and hydropower stations as well as power plants working with alternative (renewable) energy sources. It is argued that the ratio of energy sources and the energy system balance is the core basis to provide the national energy security and maintain stable power supply subject to different external environment factors. The findings have revealed the dominance of coal and natural gas production in the overall energy balance of Ukraine. However, the study of import and export trends demonstrates the prevalence of energy imports, in particular coal, oil and gas. It is observed that currently, alternative energy sources are at the infant development stage. The study of alternative energy supply in Ukraine shows that over 2018–2020 the capacity of such power plants increased by 7%, in particular, the capacity of wind stations grew by 2.3 times and solar – by 4.3 times, thus exhibiting respective change in energy output. It is also observed that during the period under consideration, the renewable energy output dropped by 17.1% while wind power production increased by 2.8 times and solar – by 5.2 times, respectively. According to the results, over 2018–2020 the capacity of wind power plants increased from 0.9% to 2.0% of the total domestic output, and solar – from 2.3% to 9.4%; as to production, the share of energy generated by wind power increased from 0.8% to 2.4%, and solar – from 0.7% to 4.1%. Given the current trend of increasing energy output generated from alternative sources, there is reason to tap a growing interest in the activities of companies offering power generating equipment in the Ukrainian market. A study on the capacity needs has revealed that the most popular among consumers of autonomous power supply systems, about 70% of total sales refer to low and medium power generators in the range of 8–550 kW. The conclusions resume that the key driver in boosting the alternative energy supply system is the relevant legal framework that encourages further alternative energy supply market development and, accordingly, the market of power generating equipment in Ukraine characterized by a strong upward growth trend.

A Novel Approach of Synchronization of Microgrid with a Power System of Limited Capacity

Currently, active networks called microgrids are formed on the basis of local power supply systems with a small share of distributed generation. Microgrids operating in an island mode, in some cases, have the ability to transfer electricity excess to an external network leading to a synchronization requirement; thus, the optimization task in terms of the system’s synchronization must be considered. This paper proposes a method for obtaining synchronization between microgrids and power systems of limited capacity based on a passive synchronization algorithm, allowing us to connect a microgrid to an external power system with a minimum impact moment on the shaft of the generating equipment. The algorithm application was demonstrated by considering a real-life object in Tajikistan. The simulation was carried out on RastrWin3. The obtained results show that the microgrid generator is connected to an external power system at an angle of 0.3° and a power surge of 29 kW, unlike the classical synchronization algorithm with an angle of 6.8° and a power surge of 154 kW (a reduction of the shock moment by more than five times). The proposed synchronization method allows us to reduce the resource consumption of the generating equipment and increase the reliability and efficiency of the functioning units of the examined power system.

Digital Identification Algorithms for Primary Frequency Control in Unified Power System

The article studies and develops the methods for assessing the degree of participation of power plants in the general primary frequency control in a unified energy system (UES) of Russia based on time series analysis of frequency and power. To identify the processes under study, methods of associative search are proposed. The methods are based on process knowledgebase development, data mining, associative research, and inductive learning. Real-time identification models generated using these algorithms can be used in automatic control and decision support systems. Evaluation of the behavior of individual UES members enables timely prevention of abnormal and emergency situations. Methods for predictive diagnostics of generating equipment in terms of their readiness to participate in the primary frequency control are also proposed. In view of the non-stationarity of the load in electrical networks, the algorithms have been developed using wavelet analysis. Case studies are given showing the operating of the proposed methods.

REVIEW THERMOMETRIC METHODS CONTROL COMPRESSION STATOR CORE STATE OF POWERFUL TURBOGENERATORS

The article is devoted to the analysis of thermometric methods of control and diagnosis of the state of compression of the stator core of the turbogenerator (TG), which have found the greatest application. It is shown that ensuring effective and high-quality control of powerful electric machines, especially power plant generators, today is an integral part of ensuring the reliability and trouble-free operation of their work. As a result of the analysis, it is shown that ensuring high reliability of operation of the generating equipment is practically impossible without their equipping with modern means of control capable to work in real-time. Bibl. 34, fig. 4.

Assessment of the diagnostic significance of modern biomarkers and hemodynamic alterations in workers of vibration-hazardous occupations

Introduction. One of the most significant tasks in modern labor medicine is to reduce the indicators of early disability in persons in contact with harmful and dangerous factors of the production environment. The issue of finding markers of early preclinical manifestations of vibrational disease and establishing comorbid conditions that are prognostically unfavorable for the course of the underlying occupational disease remains relevant. The purpose of the study is assessment of diagnostic significance of current neurospecific biomarkers and hemodynamic changes in workers of the profession related to vibration. Material and methods. The results of two studies were the basis for this work. The first, aimed at determining the concentration of neurospecific markers in the blood of miners, includes 154 working vibration hazardous professions. At the same time, groups were identified depending on the type of exposure to vibration: total (69 workers), local (24 workers) and combined general and local (61 miners) and control group of workers not in contact with vibration (49 people). The second study was performed to assess the change in hemodynamic parameters among 216 industrial workers, of which 114 people were in contact with vibration generating equipment, and 102 workers were included in the control group. Results. Data from the first study showed an increase in the titer of neuron-specific indicators, mainly protein S100B, depending on the type of exposure vibration and its seniority dose. The second study results indicated an increase in systolic blood pressure and total peripheral vascular resistance in miners under exposure to vibration factor. Conclusion. The results of both studies suggest that hemodynamic disorders and changes in the performance of neuro specific proteins may be interconnected. It seems advisable to continue the study in workers in vibrant occupations with comorbid pathology.

The initialization of initial generating equipment maintenance schedules while a heuristic method is used

Currently, heuristic methods based on iterative changing of feasible solutions set provide a perspective tool for generation equipment maintenance scheduling in power systems. Wherein effectiveness of a heuristic method depends significantly on the initial set of possible schedules or in other words quality of the method initialization. In this case, a widely used methodology of building the initial array of solutions on the basis of pseudorandom uniform generation of control variables seems to be only palliative way to access the problem. This paper proposes alternative initialization procedure drawing on the example of generating units maintenance planning with heuristic differential evolution method. The principle of this method is to get initial set of solutions utilizing normal probability distribution to generate pseudorandom deviations from the suboptimal maintenance schedule which is to be preliminarily formed using directed search method. Following this approach allows to improve probabilistic characteristics of resultant maintenance schedule in particular to decrease median value of an objective function and its coefficient of variation, and to maximize probability to get the combination of units outage moments completely suiting operational constraints.

Dental Education in the Time of COVID-19 Pandemic: Challenges and Recommendations

Moving within the second wave of the coronavirus (COVID-19) pandemic, dental education delivery has been profoundly affected by this crisis, so has the structure, evaluation, and future of dental education. Both pre-clinical and clinical dental education have experienced challenges ranging from fully online educational content to limited dental training for senior dental students. This crisis appears to be a tipping point that produced confusion in dental teaching especially clinical sciences. Although medical institutions immediately started to adapt to the unexpected COVID-19 crisis, dental and oral health educational services are profoundly impaired due to the dental team's propinquity to the patient and the aerosols generated during routine dental therapeutic procedures. Dental students unlike other medical students are considered to be at the highest risk due to the nature of their clinical training that includes working in the oral cavity of patients using aerosol-generating equipment. Some dental schools have taken the leadership and documented their modifications during this pandemic; however, there is a serious need for further investigation and wide range screening of the situation in the dental schools during the COVID-19 crisis. The aim of this mini-review is to present these challenges and how academic dental institutions have implemented strategies to overcome them.