Safety in the Operation of Electrical Networks: Inertia Compensation as a Measure of Frequency and Voltage Stability

One of the key aspects in the development of power engineering all over the world is the use of distributed small-scale generation. This is both based on fuel carbon resources with a synchronized connection between sources when they are connected to the electric power grids and renewable energy sources operated in the electrical grid via frequency converters (electronic generation). The latter brings an inevitable broad use of inverters in available AC power systems. The objectives of this paper are numerous. First is the desire to study the effect of electronic generation on modes and stability of current electrical grids and electrical power systems. Another objective is to establish requirements for electronic generation control that lets us minimize actions on relay protection coordination and automation upon the integration of electronic generation in power grids. A final objective is to increase the reliability of general electrical modes. This article shows the outcomes of the study on the statical aperiodic stability of the electrical power system upon the integration of electronic generation, requirements for its statical characteristics, and the control when operated within the electrical power system.

Main advantage of electric vehicles (EV) compared to vehicles using fossil fuels is that does not produce air pollution. One day the existence of conventional vehicles will be replaced by EV. EV gets electricity supply from batteries. When using EV, one day the electrical energy in the batteries will run out. To recharge batteries, important components such as the Electrical Vehicle Charger (EVC) are needed. EVC provides the impact of voltage drop on the electric power system bus during the charging process. This voltage drop caused by the power supply from generators cannot meet the needs of loads, including chargers and batteries. To maintain the voltage so it remains at its safe operating voltage, the same bus with EVC is interconnected with renewable energy sources. Renewable energy sources used in this study are four types of wind turbine power plants. Safe range of operating voltage in this research from 95% to 105%. This paper analyzes the change in voltage in the electric power system when the wind power plant fills EVC. The research methods section uses several scenarios. The aim is to determine the effect of each type of wind power plant on the bus voltage and EVC. Simulation results show that scenario 3 has the best results than the other scenarios. In scenario 3, voltage in bus 12 is 98,08%, voltage in bus 13 is 98,66%, and voltage in bus 14 is 98,42%. All three buses in safe limits of the operating voltage.

Clean and low-carbon energy sources and technologies have emerged as a critical driver in delivering the energy transition and achieving net zero-carbon emissions. All energy sources and power systems produce greenhouse gases (GHGs) and hence they contribute to anthropogenic greenhouse gas emissions and resultant climate change besides contributing to other negative environmental impacts. Energy sustainability remains a major challenge globally due to current heavy reliance on depletable and polluting fossil fuels for most of global energy needs. This study examines the energy transition strategies and proposes a roadmap for sustainable energy transition for sustainable energy planning and grid electricity generation and supply in wake of commitments made by the world community to the Paris Agreement aimed at reducing greenhouse gas emissions and limiting the rise in global average temperature to 2oC and preferably 1.5oC above the preindustrial level and realisation of the sustainable development goal of the United Nations. The sustainable transition strategies typically consist of three major technological changes namely, energy savings on the demand side, generation efficiency at production level and fossil fuel substitution by various renewable energy sources and low carbon non-renewable sources like nuclear power and carbon emission reduction strategies like carbon capture and sequestration and a conversion from high carbon fossil fuels like coal and oil to natural gas which remains the cleanest fossil fuel. The study demonstrated that decentralised generation with application of both demand side management and behind the meter management (BTM) strategies are effective measures to increase the use of renewable energy resources which are often locally available leading to higher uptake of renewable energy sources and conversion of consumers to prosumers making the transition economically sustainable. Waste to energy options have a significant potential to contribute to the energy transition e.g. use of biowaste for biogas production, slaughterhouse waste biodigestion for biogas and electricity generation and waste treatment and disposal, waste heat recovery from used geothermal for extra power generation and reinjection to improve the reservoir sustainability and use of bagasse and sugarcane trash for grid-based power production in sugar factories. Therefore, domestic, and industrial scale waste to energy conversion can enhance the economic sustainability of waste management process by offering useful energy substitutes for fossil fuels and enhanced energy security through decentralisation of generation. Whereas sustainable development has social, economic, and environmental pillars, energy sustainability is best analysed by five-dimensional approach consisting of environmental, economic, social, technical, and institutional/political sustainability to determine energy resource sustainability. The study recommends the adoption of sustainability-based planning for energy development and optimisation of electricity generation and supply where energy sources are analysed and ranked based on the five dimensions of energy sustainability instead of Least Cost Development Planning (LCDP) often applied by many countries. On this basis, the sustainable energy transition and optimisation of power generation will rely on both renewable and non-renewable energy since both have an important role in the realisation of the energy transition plans even though the desire is to shift entirely to renewable energy sources by the year 2050. The sustainability of various energy sources was assessed with hydrogen, wind, solar, sugarcane bagasse and cane trash, biogas and ocean energy technologies proving to be among the most sustainable renewable energy and sustainable sources. The study also examined various power plants and energy conversion systems for electricity generation in terms of their specific role and potential in grid-based power generation with hydro power plants, geothermal, nuclear, fuel cells, raking high on performance indicators like load and capacity factors making them ideal for base load power supply. Diesel engines and gas turbines using cogeneration and dual cycle systems powered by cleaner fuels like natural gas, hydrogen and biomethane will play an important role in supplying intermediate and peak load power. The study highlighted enabling technologies and concepts in the energy transition which include decentralisation of generation, cogeneration and trigeneration, demand side and behind the meter management microgrids and smart grid technologies, energy and generation planning and optimisation models, energy storage, electrification of transport and use of electric cars as decentralised electricity sources through the V2X technologies like the G2V and V2G, and carbon capture and sequestration for emissions reduction in fossil fuel power plants making them more sustainable. The study classifies electric vehicles as distributed power plants and variable loads with extensive use of energy storage while sugar cane bagasse is noted as a sustainable energy resource for power generation by cane sugar factories by application of more efficient grid connected cogeneration power plants. The study identified long project gestation period as the main factor limiting nuclear and geothermal energy deployment and recommends the adoption of modularised wellhead generators and small modular nuclear reactors (SMRs) as a solution to enhance exploitation of these sustainable energy and technologies through faster deployment with high degree of flexibility. Biogas and biomethane demonstrated significant potential as renewable energy sources for power generation and substitute fuels in all applications of fossil natural gas. The study recommends sustainability-based planning for the energy sector and power generation and use of both renewable and non-renewable but sustainable sources of energy, adoption of smart energy concept by all sectors and investment in energy technology and infrastructure development for hydrogen and other promising energy sources like ocean thermal, wave and tidal energy and the conversion of the transition from the traditional to smart grid systems and a shift from centralised to decentralised power generation. Since the transport sector accounts for a significant portion of the global greenhouse gas emissions, electrification of the transport sector and coupling with the power sector is a key strategy recommended for the transition with the smart grid and microgrids playing an enabling role. Since energy sources and generation technologies have associated emissions occurring at different sections of the lifecycle, the use of lifecycle costs and emissions are helpful in long term energy and generation planning which demonstrate that renewable sources and nuclear are the most sustainable when analysed within the five dimensions of energy sustainability, but with the non-renewable sources playing a critical role as dispatchable sources for sustainable grid power generation, while the smart grids and use of energy storage can increase the uptake of variable renewables to as high as 95% to 100% up from a low of 20-25% uptake of variable renewables with the traditional grid. This will significantly help the world in achieving the global emissions and climate targets as. stipulated in the Paris Agreement as well as the sustainable development goals (SDGs). Graphical Abstract The overall objective of the study was to provide solutions to build global energy systems based on renewable and sustainable energy resources and optimise power generation and consumption by use of sustainable energy resources and generation technologies based on the five dimensions of energy sustainability. A sustainable energy system should intergrade electricity and other sectors through smart electricity grids, smart gas grids and smart heat grids as demonstrated below.

In the paper the simplified criterion of a steady-state stability of electric power systems (EPS) is justified on the basis of Lyapunov functions in a quadratic form ensuring necessary and sufficient conditions of its performance.Upon that, the use of the node-voltage equations allows reducing study of a steady-state stability of complex EPS to study of the generator-bus system.The obtained results facilitate studies of a steady-state stability of the complex systems and have practical importance.

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Introduction. The article is devoted to the analysis of the stability of the electric power system (EPS) in mountainous areas using the Hurwitz criterion. In mountainous regions, the EPS faces a number of specific problems, such as complex terrain, remoteness of consumers and an increased probability of power transmission line failures. An important task is to develop a mathematical model that takes these features into account and to conduct an analysis of the stability of the system using the Hurwitz criterion. The purpose of the research: stability analysis of the system “high-pressure hydroelectric power plant – electric power system” using the Hurwitz criterion; identification of critical parameters of the system that affect its stability, and application of various optimization methods to improve the reliability and safety of the EPS in mountainous regions. Objects and methods. The object of the study is the high-pressure hydroelectric power plant (HPP) of PJSC RusHydro – Zaramagskaya HPP. The following methods were used for stability analysis: numerical modeling (integration of differential equations); state variable method; Laplace method; frequency response method; analytical methods for finding an exact solution to differential equations. Results and discussions. The results of the study demonstrate that the Gurwitz criterion is an effective tool for analyzing the stability of complex electric power systems, especially in mountainous areas. In the work, this method was successfully applied to analyze the static stability of the system taking into account automatic excitation control. Conclusion. A mathematical model has been developed that takes into account the specific conditions of mountainous areas. An analysis of the static stability of the system has been conducted taking into account the automatic excitation control (AEC). Critical parameters that affect the stability of the system, such as the load angle and the AEC gain factors, have been identified. It has been shown that increasing the accuracy of voltage maintenance can lead to a violation of stability in high-load modes. A method has been proposed for determining the minimum permissible gain factor, which allows avoiding aperiodic instability. Prospects for further research. In the future, possible alternative methods of stability analysis should be considered, such as frequency methods or methods based on Lyapunov theory, which could complement the results obtained using the Hurwitz criterion. A more detailed dynamic stability analysis should also be presented, which could provide a more complete understanding of the system’s behavior in transient conditions.

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This paper has details the theoretical background, development and application of a newly developed Automated Stability Assessment Tool for More Electric Aircraft Electrical Power Systems. This tool is shown to provide an easy to use and extremely flexible way for system designers to analyze Electrical Power System stability. It is shown how system parameters can be easily varied in order to investigate their impact on Electrical Power System stability. This methodology could therefore save significant time and money, both by accelerating the design process, and by helping design engineers to select the lowest cost components needed to ensure Electrical Power System stability.

Electrical power system is one among the biggest and composite systems in the world. This system may always undergoes different types of disturbances that may cause to the loss of synchronism of the system. To prevent this, Power system stabilizers (PSS) are being used in order to damp these oscillations and hence to maintain stability of the system. Lead-lag compensation methods are used in the conventional type power system stabilizer, where it have a fixed gain settings for particular operating condition. In renewable energy sources (RES) the system inertia will be decreased due to the presence of power electronic inverters used to connect to the grid. This reduction in system inertia due to large integration of RESs causes unwanted impact to micro grid dynamic stability, and hence the system security, and may also lead to total blackouts and also damages to the complete system equipment. Therefore, maintaining the dynamic security in micro grids is one of the important challenges faced by the modern electrical world. This reduction in inertia will be improved by virtual inertia based control strategy. The important control purpose of the intended work is to enhance the stability and to increase the system dynamic response. The execution of the suggested controller shows enhanced results when evaluated with the system without the controller. This work is done in SIMULINK environment and the performance of the systems are investigated.

The objective of the paper is to present a method which can be used to evaluate rapidly the transient stability of an electric power system. The stability evaluation is performed by using a fuzzy pattern recognition approach, incorporating fuzzy membership values for the system operating states. These values classify the operating states into the defined fuzzy sets representing the class of either the stable or the unstable states. The memberhsip evaluation is performed by considering the lack of a known mathematical expression for the membership values and by using the fuzzy ISODATA clustering algorithm. The developed computational method is applied to evaluate the transient stability of a sample electric power system.

The paper provides an overview of spectral and modal analysis methods for studying the stability of electric power systems (EPSs) and their control. Consideration is given to theoretical grounds of the methods and to the experience of their application for detecting the heterogeneity of the systems’ structure, identifying the coherency of generators’ motion, simplifying the mathematical model of the dynamics of EPSs, assessing their small-signal stability, and selecting the control actions to ensure it. The analysis of sub-Gramians for studying the EPS stability and other new directions in the development of the modal approach are discussed.

In recent decades, there has been an increase in the use of renewable energy sources, which serve as the basis for the concept of distributed generation, that is, facilities that produce electricity at the location of consumers. The large-scale introduction of distributed generation affects the reliability and stability of electric power systems, including by reducing power losses in them by reducing the current in the lines. Taking into account the forecasts of many experts on the growth of distributed energy resources, the issue of studying methods for reducing electrical energy losses in distribution grids containing renewable energy sources is relevant. (Research purpose) The research purpose is determining methods for reducing electricity losses in electric grids containing renewable energy sources. (Materials and methods) Presented an information search, including an overview of Internet sources and sources of scientific literature devoted to methods of reducing electricity losses in electric grids. (Results and discussion) They used Yandex and Google search engines, Scopus, Web of Science and Google Scholar scientific databases, Cyberlenink electronic libraries as sources of information, eLIBRARY.ru , Elsevier, Springer, IEEE Xplore. It was shown that the literary analysis included 59 sources most suitable for the research topic, of which 8 sources of information are given in Russian, 51 in English. In the course of the information search, we determined methods for reducing electricity losses both in traditional electric grids and in electric grids containing renewable energy sources. (Conclusions) It was found out that the considered methods inherent in traditional power supply grids are also relevant for networks with renewable energy sources. It was revealed that the use of renewable energy sources in itself also allows to significantly reduce electricity losses in electric grids due to distributed generation

This paper presents an analysis of the instability of the electricity generation of renewable energy sources (RESs), specifically Digital Twins of RESs. The first part deals with the analysis of RES electricity generation around the world and Ukraine. The following chapter describes features of functioning power grids in modern conditions in Ukraine and ways to ensure the balance reliability in the power system for conditions of high-grade RES integration. The rapid increase in electricity generation RESs causes control problems of distributed power supply in the power grid. A mathematical model of the parameter controls in normal mode electric power systems for conditions with high integration of RESs is proposed in the second part. The study investigates components of the optimality criterion at the control of normal mode parameters of the electric power system with RESs. In general, digital transformation helps decarbonize the energy supply, decrease dependency on fossil fuels, and integrate renewables into power systems. A model Digital Twin (DT) of a photovoltaic system, or an exact 3D visualization, analyzing the accumulator system depending on load and generation, are presented. The problems of Digital Twin are very widely discussed, but many papers and studies are general without any practical implementations. The main part of this paper focuses on research and deals with daily electricity generation from different kinds of RESs, namely mini-hydropower stations, photovoltaic power stations, and wind power stations. Measured data of electricity generation from photovoltaic power plants, wind power plants, and mini-hydropower plants and obtained meteorological factors were used for the calculation of Spearman’s, Kendall’s, and Pearson’s correlation rank coefficients. The main contribution of this research is to determine the main metrological factors for each kind of studied RES. In the future, it will help to decide the task of forecasting power generation more presciently. Additionally, the presented model of DT RESs allows the installation and operation of grids with higher efficiency, because it can help to predict all influences, from shading up to the optimization of the battery storage system.

The article studies the efficiency of using electrical energy storage (EES) for increasing the stability of electric power systems with renewable energy sources (RES). The status of renewable energy sources and energy storage systems development in Russia is analyzed. The main methods of increasing the stability of the power grid with RES are considered, as well as technological and legal aspects of the RES integration into the power grid. “ETAP” model of the power system of the South of Russia was created, consisting of 11 generators, 49 transmission lines, 28 transformers, and 186 static loads. Generation of RES-based sources has been modeled using the real data on the wind and solar potential of the region where the grid is located. The study has produced daily schedules that characterize the RES power output for summer and winter days with and without EES operating. The patterns of the change in the constant inertia of the system during the day have been obtained. Conclusions have been made on the impact of EES on the stability of parallel operation of the power grid with RES.

The effectiveness of power plants of various types in Russia (Siberia and the Far East) and neighboring Asian countries (China, Korea, Japan) was evaluated according to the criterion of the cost of generated electricity. Differences in energy development conditions in these countries (technical and economic indicators of power plants etc.), prices of fossil fuels, climatic characteristics) was taken into account. Two options for the use of renewable energy sources (RES) are considered - unfavorable and favorable (basic and ecological). They differ in the values of RES capacity factor due to different climatic conditions, as well as charges for carbon dioxide emissions (carbon tax). It is shown that under conditions that are less favorable for renewable energy sources, fossil fuel power plants or nuclear power plants are the most economical options. The dependences of the electricity cost on the carbon tax under favorable conditions for renewable energy have been obtained. Values of carbon tax, at which renewable energy sources produce cheaper electricity than organic-fueled power plants have been found.