Development Of Electric Power System Research Articles

Development of methodological foundations for analyzing the system reliability of modern electric power systems

The article discusses issues related to improving the methodological foundations for analyzing the system reliability of electric power systems. In particular, a decomposition of the complex property “system reliability” is presented, which covers all stages of control of electric power systems. In accordance with the new decomposition, system reliability is formed by three components: security (operational reliability), planned reliability and adequacy. Each of the components is designed to solve specific problems at various stages of managing electrical power systems. Thus, the methodological apparatus for analyzing adequacy should mainly be used when solving problems of designing the development of electric power systems, the methodological apparatus for analyzing planned reliability should be used when solving problems of work planning (states and balances), and the methodological apparatus for analyzing security when solving problems of operational management. Unlike the concepts of adequacy and security, the concept of planned reliability is new. The article presents the rationale for introducing the concept of “planned reliability” into the practice of managing electric power systems. The main differences between planned reliability and security and adequacy are reflected. The basic requirements for the methodology for assessing the planned reliability of electric power systems are formulated. It is indicated that when assessing the planned reliability of electric power systems, it is necessary to take into account a number of random processes in the functioning of energy facilities, such as energy storage systems, hydroelectric power plants, renewable energy sources and others, and this requires the use of the mathematical apparatus of random processes in the functioning of systems. To assess planned reliability, it is proposed to use the sequential Monte Carlo method.

New Electric Power System Stability Evaluation Based on Game Theory Combination Weighting and Improved Cloud Model

The development of new electric power system is a requirement for China to realize its “carbon peaking and carbon neutrality goals”, so it is of great importance that we assess the stability of a new electric power system under certain conditions. Firstly, according to the factors affecting the stability of the new power system, the characteristics of the new electric power system are analyzed in depth, so as to establish a stability evaluation index system including four first-level indices of safety, adequacy, flexibility, and adaptability. Secondly, a stability evaluation model is proposed. Based on the game theory, the entropy weight method, criteria importance though intercrieria correlation (CRITIC) method, and coefficient of variation method are combined and assigned, and the cloud model is improved through the combination of weights, which is used for evaluating the stability of the new electric power system. Finally, the applicability of the proposed evaluation model is verified by an arithmetic example analysis, which can identify the vulnerability of the new electric power system and provide suggestions for improving its stability. The model can provide a theoretical basis for promoting energy transition and sustainable development.

Construction of the structure of rural electric networks taking into account the availability of renewable sources of electricity

It is noted that although the share of renewable electricity sources continues to grow and develop rapidly, the industry still faces many challenges, including how to continue to reduce electricity losses and annualized costs, improve operation and maintenance efficiency, maintain grid stability, ensure safety and reliability of the power supply system containing renewable sources of electrical energy. It is shown that an effective solution to these problems is possible only on the basis of the analysis of the prospects for the development of local electric power systems that contain renewable sources of electric energy, the development of technical and organizational support mechanisms that will contribute to the construction of modern system (schematic) solutions. It is proposed to apply the potential surface method for building the optimal structure of the rural electrical network during its design and modernization in the presence of renewable sources of electrical energy, which allows optimizing the structure of the network from the point of view of electrical energy losses and reducing annualized costs. The algorithm for forming the structure of power supply systems is described, which implements the simultaneous solution of the tasks of determining the number of load nodes, distributing electrical receivers between them, determining the design of power sources, taking into account the discreteness of the design of system elements. The results of numerical modeling based on the proposed algorithm are presented on the example of solving the problem of reconstruction of a section of the rural electricity network.

Construction of the structure of rural electric networks taking into account the availability of renewable sources of electricity

It is noted that although the share of renewable electricity sources continues to grow and develop rapidly, the industry still faces many challenges, including how to continue to reduce electricity losses and annualized costs, improve operation and maintenance efficiency, maintain grid stability, ensure safety and reliability of the power supply system containing renewable sources of electrical energy. It is shown that an effective solution to these problems is possible only on the basis of the analysis of the prospects for the development of local electric power systems that contain renewable sources of electric energy, the development of technical and organizational support mechanisms that will contribute to the construction of modern system (schematic) solutions. It is proposed to apply the potential surface method for building the optimal structure of the rural electrical network during its design and modernization in the presence of renewable sources of electrical energy, which allows optimizing the structure of the network from the point of view of electrical energy losses and reducing annualized costs. The algorithm for forming the structure of power supply systems is described, which implements the simultaneous solution of the tasks of determining the number of load nodes, distributing electrical receivers between them, determining the design of power sources, taking into account the discreteness of the design of system elements. The results of numerical modeling based on the proposed algorithm are presented on the example of solving the problem of reconstruction of a section of the rural electricity network.

Analysis of the Design and Application of a Novel CT Secondary Cable Line Calibrator

With the rapid development of electrical power systems, ensuring the accuracy and reliability of power transmission has become particularly crucial. The secondary cable line calibrator for current transformers (CT) plays an essential role in calibrating electrical power systems. It is not only related to the safe operation of the system but also directly impacts the accuracy of energy metering. This study aims to design and analyze an efficient CT secondary cable line calibrator to explore its application effects in the power system. By thoroughly analyzing the characteristics of CT secondary cable lines and the design requirements of the calibrator, this paper proposes an innovative design scheme for the calibrator. This device demonstrates significant effects in enhancing the accuracy and stability of power system calibration, providing robust technical support for the optimization and upgrade of the power system. This research not only offers a theoretical basis and practical guidance for the design and application of CT secondary cable line calibrators but also contributes new ideas and methods for the precise calibration and efficient management of the power system.

Choosing Optimal Supply Radius of Transformer Substations (TSs) in Iraq’s Cities Using Geometric Programming with Neutrosophic Coefficients

Numerous uncertainties exist in various electricity power system problems due to the size, complexity, geographical distribution, and influence of unforeseen events in these systems, making it difficult for traditional mathematics tools based on crisp set theory to have an impact on and solve many power system problems. As a new branch of mathematical uncertainty techniques, the neutrosophic expert systems approach has therefore emerged with the development of electric power systems and has proven successful when correctly linked. The expert typically uses ambiguous or neutrosophic language to describe their empirical knowledge, such as "very likely," "quite likely," "if x is large, then y is very likely to occur," "x should not be less than a," etc. To design an optimal radius of power supply in the electrical transformer substation, this article presents a new method for creating primal and dual neutrosophic geometric programming problems. It also provides a numerical example to evaluate the approximate optimal economic power supply radius.

Распределенная система станций подзарядки для энергообеспечения группы БпЛА мультикоптерного типа

A steady trend towards the development of electric power systems leads to their continuous enlargement and sophistication. As a result, new ways of their control appear. In this regard, the existing models and complexes for adequacy assessment may work inadequately and ineffectively in terms of the obtained results adequacy. To assess the current state of the existing models and complexes, we reviewed and analyzed the domestic and foreign software and computer systems. In particular, we considered mathematical models of minimizing the power shortage. This work is based on the problem of modifying mathematical models of minimizing the power shortage used in adequacy assessment of the electric power systems of one of the complexes under consideration. As a modification of mathematical models, it is proposed to exclude the existing method of using the line capacities and start using correct accounting for the maximum permissible active power flow in controlled sections. The experimental part reflected in the paper concerns the testing of options for models to minimize the power shortage, as well as the proposed modifications on various systems, including those consisting of three and seven reliability zones with a variable number of controlled sections and power lines included in them. The results of the study have shown that the proposed modifications are efficient and can be used in the future. The authors also obtained the most adequate results in terms of the physical laws of electric power system operation due to the model of minimizing the power shortage with quadratic losses which takes into account the limitations of power transmission over controlled sections.

Working cycle condition construction for electric wheel loader based on principal component analysis and cluster analysis

With the rapid development of new energy technology, cycle condition is significant for the design of powertrain system, whole machine economy, endurance, and other performance parameters of pure electric drive machines. Many cycle conditions of the passenger car industry have been defined. While that for the loader which has complex operation modes and working conditions, has less research on this aspect. Cycle conditions suitable for loader have not been constructed. To support the research and development of electric loader power system, the cycle conditions that can reflect the driving characteristics of electric loader are studied in this paper. According to the typical “V” cycle condition of loader, the actual driving condition data are collected and the kinematic segments are divided. The kinematic segments are grouped into five categories by using principal component analysis and K-means clustering algorithm to obtain the clustering center of each category. The working cycle condition is formed by extracting the combination of segments closest to the clustering center. Finally, based on AMESim simulation and whole machine test analysis, the error between the simulation and vehicle test results of the energy consumption is 3.4%. The accuracy and effectiveness of the proposed constructed cycle conditions are verified.

Development of an interval double-stochastic carbon-neutral electric power system planning model: A case study of Fujian province, China

Synergic adoption of diverse measures and consideration of multiple uncertainties are essential for electric power systems to achieve carbon neutrality. To fill the research gap, an interval double-stochastic carbon-neutral electric power system planning (abbreviated as IDS-CEP) model is developed. In the IDS-CEP model, reduction measures include electricity mix improvement, CO2 capture, transport, and storage (including monoethanolamine absorption and membrane separation), CO2 direct air capture (containing solid adsorption technique and liquid adsorption technique), ecosystem carbon sinks (forest, farmland, and ocean); uncertainties involve stochastic electricity demand, CO2 emission allowance, CO2 emission coefficient, and other interval parameters, which are quantified as forty-five scenarios and three levels. Through the application in Fujian province (China), results disclose that: (i) combination of the reduction measures would help Fujian achieve carbon neutrality with minimized system cost by 2060, their contributions could averagely be ranked as electricity mix improvement (70.75%) > forest (6.03%) > monoethanolamine absorption (5.98%) > farmland (4.53%) > solid adsorption technique (3.83%) > membrane separation (3.45%) > ocean (3.35%) > liquid adsorption technique (2.08%); (ii) to guarantee electricity supply, total installed capacity should be expanded to [156.16, 197.78]GW, where low-carbon electricity (especially nuclear, wind and photovoltaic electricity) installed capacity would occupy [74.68, 76.66]% by conducting electricity mix improvement to reduce CO2 emission; (iii) the changes in electricity mix structure would lead to decreased water utilization (by [48.57, 61.54]%) and pollutant emissions (by [77.00, 87.35]%); (iv) uncertainties would significantly affect decisions about electricity generation and CO2-emission reduction, resulting in varied system costs (in a wide interval of [6.07, 9.16] × 1012 RMB¥). Authorities can choose appropriate schemes according to their risk attitudes towards uncertainties. Results provide scientific planning support for Fujian's electricity generation sector; meanwhile, the IDS-CEP model can also be used in other regions by updating data information.

Integration of calcium looping and calcium hydroxide thermochemical systems for energy storage and power production in concentrating solar power plants

Energy storage is a key factor in the development of renewables-based electrical power systems. In recent years, the thermochemical energy storage system based on calcium-looping has emerged as an alternative to molten salts for energy storage in high-temperature concentrated solar power plants. This technology still presents some challenges that could be solved by integrating the thermochemical energy storage system based on calcium hydroxide. This work studies a novel concentrated solar power system integrating calcium-looping and calcium hydroxide thermochemical energy storage systems. The results show that the combined use of hydration-dehydration cycles in the calcination-carbonation processes of the calcium looping for energy storage could partially solve the issue related to the multicyclic deactivation of calcium oxide. The improvement in the conversion of calcium oxide during carbonation is demonstrated experimentally when hydration-dehydration cycles are combined. Numerical simulations demonstrate the technical feasibility of the integrated process, with efficiencies ranging between 38-46%, improved with the increase in calcium oxide conversion in the carbonator, showing the potential of the proposed integration.

An Improved Three-point Method for Power Flow Calculation based on Halton Sequence

With the development of electric power system, it is necessary to expand the scale of new energy power generation to meet the demand of peak cutting and valley filling. The new energy power generation presents intermittenity and volatility, so it is a hot research topic to use the theory of point estimation method to study the power system planning based on uncertainty quantity. This paper improved the three-point estimation method in probabilistic power flow calculation, combined with Halton sequence sampling method to make sampling samples more uniform, and then added a pair of estimation points on the basis of the three-point estimation method, so as to improve the precision of power flow calculation without calculating the fourth moment. The proposed method is verified on IEEE14 and IEEE33 node systems, and the results verify the rationality of the improved three-point method based on Halton sequence.

ANALYSIS OF THE FEATURES OF EFFECTIVE IMPLEMENTATION OF SOLAR POWER PLANTS IN LOCAL ENERGY SUPPLY SYSTEMS

It is shown that renewable energy sources (RES) are increasingly dominating the electricity market in many countries, while the amount of electricity generation by solar power plants (SPP) has been growing at a record pace in recent years. It is noted that although the share of RES continues to grow and the photovoltaic industry is developing rapidly, the industry still faces many challenges, in particular, how to continue to reduce the Levelized Cost of Energy (LCOE), improve the efficiency of operation and maintenance, and maintain the stability of the power grid, to ensure system security. The effective implementation of solar generation requires an analysis of the prospects for the development of local electric power systems that include SPP, the development of mechanisms and appropriate regulatory, methodological, technical and organizational support that will contribute to the effective development of solar generation, the construction of modern system (schematic) solutions.
 The analysis of the features of the development of green generation in Poland and Ukraine was carried out, the positive factors that influenced the development of renewable energy sources in Ukraine were determined, which made it possible to form the technical, economic and organizational conditions for the successful development of solar generation, in particular, information was provided on new players in developed energy markets according to the Fourth Energy EU package. The analysis showed that when increasing the efficiency of SPP systems, planning and demand management in the electric network, effective functioning of Energy Smart Community (ESC) become important.
 The basic components of the effective functioning of electric power systems with SPP are highlighted, namely: concepts of configurations of photovoltaic systems, Smart-inverters, Energy Storage System (ESS), formation of Virtual Power Plant (VPP) based on SPP. It is shown that each of the four concepts involves the connection of a series of photovoltaic panels or strings and power electronics devices (DC converters and inverters), which are configured taking into account the peculiarities of the functioning of various structural (schematic) solutions. The advantages of using Smart-inverters as a new technology that can help integrate solar energy and other distributed energy resources into the electrical network are evaluated. Smart inverters are used to help the electrical grid cope with intermittent generation, helping the electrical grid remain stable and maintain voltage and frequency requirements.
 It was determined that in any photovoltaic system, the ESS itself becomes a central component that significantly affects the cost, maintenance requirements, reliability and design of the SPP, and the important parameters of the ESS that affect the operation and performance of the photovoltaic system are the battery maintenance requirements, battery life, available power and efficiency. Trends in the market of advanced energy storage systems for SPPs for the next decade are presented. The functioning of virtual power plants based on SPP, as a network of aggregated distributed energy resources that are remotely connected and work together with flexible electricity consumers, is aimed at maximizing the benefits of participants. The possibilities and trends of SPP development in the near future, which are based on the research of Huawei, are presented.

Effects of Y-nodes in DGEBA/TDE-85/MTHPA blends on their thermal and mechanical properties: MD simulation and experimental study

With the development of alternate electrical power system and the improvement of voltage level, the operation conditions faced by epoxy resin (ER) insulation materials are becoming more and more complex. The traditional ER materials have been difficult to meet the increasingly stringent requirements. In this paper, the thermal and mechanical properties of DGEBA/TDE-85/MTHPA blend system were studied by molecular dynamics (MD) simulation and experiment. The results show that the addition of TDE-85 can significantly improve the thermal and mechanical properties, and the comprehensive improvement effect is the best when the molar ratio of DGEBA and TDE-85 is about 8:2. The experimental results are consistent with the simulation results. Further analysis of the micro-parameters of the monomer and the cross-linking network found that the torsional energy barrier of TDE-85 is higher than DGEBA. And the compatibility of the two ER is better when the ratio is 8:2. In addition, TDE-85 can introduce high-stability Y-nodes into the system, making the cross-linked network more stable, which has a significant effect on improving the thermal and mechanical properties. The research provide a reference for the blending modification of high-performance ER for high-voltage insulation.

Анализ влияния объектов распределенной генерации на системы защиты и режим напряжения: обзор

In recent decades, in the process of restructuring energy systems, centralized energy sources are being replaced by decentralized ones. This led to the emergence of a new concept (power generation) in power supply systems, especially in distribution systems, known as «distributed generation». Distributed generation was introduced into the power systems, especially at the low voltage level, to make them more reliable, safer and efficient. At the same time, various problems appeared in the power supply systems that require solving issues of ensuring the selectivity and sensitivity of the protection action, maintaining the required voltage level. Since the current and future trends in the development of electric power systems are aimed at increasing the integration of distributed generation, especially through installations, made based on renewable energy sources, it is required to conduct studies on the impact of these generation technologies on the distribution networks. When using distributed generation, setting up the protection system is associated with the problems associated with changes in the magnitude and direction of emergency currents. Distributed generation installations affect the fault current in a certain way, while influencing the overcurrent protection systems in terms of their coordination. In this regard, the alternative protection systems and algorithms can be used, such as directional overcurrent relays. In addition, highly penetrating distributed generation devices such as photovoltaic installations can cause overvoltage in the distribution systems, which must be effectively prevented. Thus, the paper considers the problems caused by the distributed generation and related to protection systems and voltage regulation in the distribution networks. Solutions for mitigating the negative impact of distributed generation on the power supply systems are proposed and considered in detail.

Ensuring balance reliability in managing the development of electric power systems with renewable energy sources

The issues of substantiating balance reliability - reserves of the generating power of the EPS in the presence of renewal power in the standpoint of achieving the required normative indicators of balance reliability and the execution planned volumes of electricity generation at the wind power plants (WPP) and solar power plants (SPP) in the balance sheet. The results of substantiation reservation tools are given for various scenarios for the development of SPP and WPP both in power and the production of electricity.

Information content the task of balance reliability in managing the development of electric power systems

The issues of influence initial information on the obtained indicators of balance reliability are considered. The analysis new methodological instructions (MI) developed and approved by Russian Ministry of Energy from the position of possibilities information filling the task of assessing the indicators of balance reliability is given.

Ensuring balance reliability in managing the development of electric power systems: condition, problems, information content

The stages of improving the methodological and model support problem of balance reliability in recent years from the standpoint of developing new methodological instructions (MI) on the design of power systems are considered. The analysis of the developed and approved by the Russian Ministry of Energy and the impact of their application on the decisions made.

An advanced method for improving the reliability of power losses probabilistic characteristics calculation to determine the optimal wind power capacity and placement tasks

Due to the trend of increasing electricity consumption that has observed over the past decades, the sustainable development of electric power systems is a relevant task. Taking into account the desire of the leading countries for energy independence, low-carbon energy based on renewable energy sources is being actively penetrated nowadays. One of the main tasks for the renewable energy sources installation into existing electric power systems with no additional changes in network is to maximize power generation with the lowest power losses and to comply with the grid requirements. Considering the stochastic nature of renewable energy, various optimization algorithms are being developed and used for this task. In this regard, numerical methods of deterministic and probabilistic modeling of power systems with, e.g., wind turbine generators are used to determine the optimal placement and capacity. The main problem is that obtaining a reliable result by actual statistical and heuristic methods, based mostly on a group of Monte Carlo methods, does not have a full solution in the whole range of functional dependence, due to the complexity of modeling the input arguments of rare repeatability. As part of the solution to the optimal power flow problems, namely, not exceeding the specified probability density functions of the state parameters, it can lead to false conclusions. This paper proposes a methodology for calculating the probabilistic characteristics of steady-state parameters, increasing the reliability and speed of their calculation by taking into account the values of rare repeatability. The results of research is the refinement of the power flow values (compared with the Monte Carlo method) using the developed method based on selection of interval boundaries of input and output probabilistic data (SIBD method), and the definition of minimum possible power losses as part of the problem of determining the optimal wind power capacity and placement in power system for IEEE-14 and IEEE-57 schemes.

The energy storage mathematical models for simulation and comprehensive analysis of power system dynamics: A review. Part II

With the development of electric power systems, especially with the predominance of renewable energy sources, the use of energy storage systems becomes relevant. As the capacity of the applied storage systems and the share of their use in electric power systems increase, they begin to have a significant impact on their dynamic properties. Accordingly, when solving the issues of design and operation of power systems with energy storage systems, it becomes necessary to take into account their properties. For this purpose, depending on the type of energy storage, different mathematical models have been developed, with varying degrees of detail. At that, for a number of researches it is necessary to apply detailed mathematical models, but simplified models are also widespread. In article approaches in simplification of detailed models of energy storage systems with their mathematical description are described, the area of their application is considered. The authors also give some limitations and disadvantages associated with the use of simplified models. The article is a review and can help in choosing a mathematical model of the energy storage system to solve the necessary problems in the mathematical modeling of storages in electric power systems.

Development of PMU-Based Transient Stability Detection Methods Using CNN-LSTM Considering Time Series Data Measurement

The development of electric power systems has become more complex. Consequently, electric power systems are operating closer to their limits and are more susceptible to instability when a disturbance occurs. Transient stability problems are especially prevalent. In addition, the identification of transient stability is difficult to achieve in real time using the current measurement data. This research focuses on developing a convolutional neural network—long short-term memory (CNN-LSTM) model using historical data events to detect transient stability considering time-series measurement data. The model was developed by considering noise, delay, and loss in measurement data, line outage and variable renewable energy (VRE) integration scenarios. The model requires PMU measurements to provide high sampling rate time-series information. In addition, the effects of different numbers of PMUs were also simulated. The CNN-LSTM method was trained using a synthetic dataset produced using the DigSILENT PowerFactory simulation to represent the PMU measurement data. The IEEE 39 bus test system was used to simulate the model under different loading conditions. On the basis of the research results, the proposed CNN-LSTM model is able to detect stable and unstable conditions of transient stability only from the magnitude and angle of the bus voltage, without considering system parameter information on the network. The accuracy of transient stability detection reached above 99% in all scenarios. The CNN-LSTM method also required less computation time compared to CNN and conventional LSTM with the average computation times of 190.4, 4001.8 and 229.8 s, respectively.