Academic literature on the topic 'Uneven daily load schedules of the power system'

The activity of any enterprise is always associated with risk. This is especially true of hydropower enterprises, since they work in the conditions of renewable energy sources, which are directly dependent on nature. This necessitates the introduction of the concept of risk management, which will take into account risk factors in the process of developing and approving management decisions.Hydroelectric power plants play an important role in ensuring the required quality of electrical supply, participating in regulating voltage and frequency, covering the uneven part of daily load schedules, guaranteeing measured operation modes of nuclear and thermal power plants, increasing the safety and economy of operation of the final cycles load, performing the function of a temporary emergency and operational power reserve.The purpose of this article is to analyze the characteristics of risk management in hydropower, as well as to justify the development and feasibility of introducing the concept of risk management in hydropower.

Information about the problems arising from the uneven production and consumption of energy in power systems, including in the power system of the Republic of Uzbekistan, is given on the example of a daily electrical load schedule. It is noted that to successfully solve these problems, energy is accumulated in the hours of minimum consumption so that it can be used in peak hours with high consumption, and for this purpose, pumped storage power plants are used. A diagram of hydraulic energy storage is given at large pumping stations used to accumulate water in the upper reservoir in hours of minimum loads, and the accumulated volume of water is directed to generate energy, which can be used by pumping stations to supply additional water to its consumers, replenishing its losses in hours of hydraulic energy storage. The method of selection and optimization of the main parameters of this complex, based on minimizing fuel consumption in power plants while limiting the amount of accumulated energy based on the capabilities of water and energy resources of pumping stations, is presented. The calculations using the example of the Syrdarya thermal power plant show that with the integration of five nearby pumping stations into the process of energy storage and generation, significant cost savings are achieved, and the daily load schedule is significantly leveled.

One of the innovative directions of the prospective development of electric power complexes of the countries of the world is the technology of smart power supply networks, the main element of which is the system of industrial energy storage. They began to be widely used for use as local energy storage devices used in combination with renewable energy sources. The purpose of the study is to analyze the influence of the shape of the graphs of consumers' electrical loads on the effect obtained in the process of price-dependent energy management based on industrial energy storage systems in the current conditions of procurement in the wholesale and retail electricity markets of Russia. The methods of analysis, synthesis, and systems approach are used. To carry out the study, we took data on the characteristics of typical graphs of electric loads of various types of large consumers, price parameters of electricity supply from the retail electricity market, valid for consumers of the Central Federal District. Based on the three basic types of hourly electricity consumption schedules, which have different indicators of daily load factors, calculations were made of changes in the parameters of the cost of electricity purchases and average prices for the purchase of electricity, as well as the comparative characteristics of cost parameters and average prices were revealed. Based on the analysis of the parameters of the cost of electricity and average purchase prices, the example of the Voronezh region investigated the direction of change in the total cost of electricity purchases and average purchase tariffs as the fill factor of daily load schedules changes. The dependence of the effects of lowering the average price of electricity purchases on the fill factor was revealed. Based on the data on the price parameters of all electric power components for the regions of the Central Federal District, the cost parameters and average tariffs for the purchase of electricity were calculated, which made it possible to identify the uneven parameters of both the monthly costs of purchasing electricity before and after the use of electric energy storage systems, and the parameters for reducing the average purchase tariffs electricity after applying storage systems. The analysis of the effects of the use of energy storage systems for different demand schedules and levels of rated voltage was carried out, which revealed a tendency to increase the effect of a decrease in average prices for the purchase of electricity as the level of rated voltage decreases. The results can be used by employees of energy companies in Russia or energy services of industrial enterprises of the Central Federal District in the process of analysis of investment projects on the use of industrial energy storage systems.

A characteristic feature of the present day development of power engineering lies in the increase in the unevenness of power systems schedules. The structure of generating powers of Ukrainian energy engineering is overloaded with basic powers and characterized by a sharp deficit of maneuvering wanes. To cover the uneven load of the power system during the operation of existing and construction of new power plants, it is necessary to take into account the possibility of their operation under maneuvering modes. This paper determines the influence of work of power plants i under maneuvering modes on the specific consumption of conditional fuel on the released electric energy at working on gas or coal fuel. Fuel consumption for starting of a unit depends on its type and downtime in reserve. The use of steam–and–gas facilities and gas turbines helps to enhance the maneuverability of power plants. Alternative options for the development of thermal energy are the introduction of gas–piston power plants and power units with fluidized–bed boilers. We present formulas for the calculations of fuel consumption on by power units for start–ups and specific consumptions depending on the load and degree of their involvement to regulating loads for different thermal energy technologies: steam–turbine condensation and district heating power units; steam–and–gas and gas turbine plants; gas piston installations; power units with fluidized bed boilers. For enhancing the maneuverability of power plants, working on fossil fuels, their modernization and renewal of software are necessary. Quantitative assessment of the efficiency of power units and separate power plants during their operation under variable modes is important for forecasting the structure of generating capacities of power systems, the need to introduce peak and semi–peak capacities, the choice of the most profitable composition of operating equipment at different schedules of electrical loads Keywords: thermal power, power unit, maneuverable mode, electrical load, specific fuel consumption

The aim of this work is to develop approaches for a methodology creation that allows estimate preliminary assessment of the power consumption management potential in the absence of experimental data on the object under actual load study. Analysis of diesel power plants operating modes in such systems showed that diesel generators often operate in suboptimal load ranges, which leads to increased diesel fuel consumption, reduction in diesel generators service life andas a result of poor diesel fuelcombustion in the cylinders or increased mechanical parts wear, etc. At the same time, electricity demand management technology used in large centralized power supply systems in some countries of the world can be adapted for use in isolated low power systems. Considering that diesel power plants are the sources of distributed generation in the power systems of hard-to-reach facilities in mountainous areas, demand management will allow to align the daily load schedule, plan the loading, start-ups and stops of diesel generators to improve the technical, economic and environmental performance of the entire complex. This paper proposes a technique that allows estimate preliminary assessment of the object shiftable electrical load share on the basis of "base" data about a typical similar object. The initial data isthe average electrical load daily schedules for each month of the studied object, for example, a settlement. The schedule of non-shiftable partof the studied object load is constructed by scaling the base non-shiftable load schedule depending on the selected method: the series values of base schedule can be multiplied by a coefficient so that one of the base schedule values becomes equal to the corresponding series value of the studied object load schedule, and other base schedule values were less than or equal to the corresponding values. According to the second method the base schedule values can be multiplied by a coefficient so that the series values at the selected hour (for example, evening maximum) were equal to the corresponding series value of the studied object load schedule. An example of methodology application is shown to estimate the demand response potential for electricity in the Amderma settlementresidential sector in Arkhangelsk region. It also shows the calculation results of technical, economic and environmental effect of the demand side management technology, due to electric load schedule alignment and, as a result, diesel generators operationin modes close to optimal.

This paper reports on the results of a comparison between short-term indoor testing and long-term outdoor monitoring of solar domestic hot water systems. Five solar-preheat systems were monitored under side-by-side conditions of irradiance and load, for a period of two years. The systems were then tested according to a standard day test, using a solar simulator, and a load schedule identical to that imposed on each system during the monitoring. The systems were found to deliver 19.7 MJ–25.8 MJ daily in the test, compared to a two-year average of 19.1 MJ–26.0 MJ (1.5 to 2.0 GJ/m2 annually) outdoors. System rank was reasonably well preserved. Comparison of results on the basis of efficiency and solar fraction suggests that good correspondence exists between long-term outdoor results and those of indoor testing, at least for systems with stable controllers. Selected systems were also tested at different load schedules and radiation levels. Methods of predicting the performance of a solar-preheat system from the results of a standard day test are discussed, and the possibility of reducing testing time to a single day is explored.

Development of the experimental installation for testing of the software and hardware tools of management of a photovoltaic system of a local facility connected to the grid, which, along with checking its operability, will allow analyzing the operation and adjusting the settings of systems with different parameters under different weather conditions, load schedules and operating modes. Method. Experimental research with preliminary justification of settings based on calculations and simulation data obtained in the Matlab software package. Results. The structure and experimental installation on the base of the photovoltaic system with storage battery and using a photovoltaic battery emulator with software control of generation and load power were developed. The software modules of the system have been developed. According to the results of the simulation, the moments of time are determined when the operating mode is switched in the experimental setup. The experimental setup was tested in static and dynamic modes. Static tests were aimed at checking the functioning of the photovoltaic battery emulator in accordance with the specified solar radiation power and the temperature of the photo module, as well as checking the correctness of the model used in the program. Tests in statics with fixed parameters and in dynamics in the daily cycle, in general, confirmed the efficiency of the proposed solutions. Scientific novelty. The method of experimental research in the daily cycle of photovoltaic systems control with the use of software-controlled emulators of a photovoltaic battery and load with power and time scaling was developed. This, along with the acceleration of the experiment, allows us to estimate the effectiveness of the tested systems at different ratios of system parameters and adjust the functioning algorithms. Practical importance. The proposed solutions for the implementation of the experimental installation allow minimizing material costs and time costs in the process of testing and development of software and hardware control tools of a photovoltaic system with storage battery.

The increasing peak-to-valley load difference in China pose a challenge to long-distance and large-capacity hydropower transmission via high-voltage direct current (HVDC) lines. Considering the peak shaving demands of load centers, an optimization model that maximizes the expected power generation revenue is proposed here for the long-term operation of an interprovincial hydropower plant. A simulation-based method was utilized to explore the relationships between long-term power generation and short-term peak shaving revenue in the model. This method generated representative daily load scenarios via cluster analysis and approximated the real-time electricity price of each load profile with the time-of-use price strategy. A mixed-integer linear programming model with HVDC transmission constraints was then established to obtain moving average (MA) price curves that bridged two time-coupled operations. The MA price curves were finally incorporated into the long-term optimization model to determine monthly generation schedules, and the inflow uncertainty was addressed by discretized inflow scenarios. The proposed model was evaluated based on the operation of the Xiluodu hydropower system in China during the drawdown season. The results revealed a trade-off between long-term energy production and short-term peak shaving revenue, and they demonstrated the revenue potential of interprovincial hydropower transmission while meeting peak shaving demands. A comparison with other long-term optimization methods demonstrated the effectiveness and reliability of the proposed model in maximizing power generation revenue.

We propose a model of mathematical programming with integer variables, the use of which provides a search for the optimal modes of redundancy and loading of storage capacities of the power plants in Ukraine with covering the daily schedule of electrical loads. The main purpose of this work is to create a tool for studying the possibilities of optimized dispatching of generating capacities of thermal power plants, as well as generating and reserve capacities of high-power storage units within the IPS of Ukraine, the limits of permissible values of the parameters of generating and storing capacities, at which stable balanced operation of the energy system is possible. The model enables one to determine the optimal modes of using generating and storing capacities for covering the schedule of electrical loads without using storage and with using storage at different values of the total installed and peak power of SES and wind farms. The model takes into account the specific features of the operation of reserve and storage capacities of the Ukrainian energy system – the maximal possibilities for change in the power of storage and generation of electricity units of the Ukrainian energy system and possibility to provide support for frequency recovery reserves (secondary regulation) at a given level, located at thermal power plants, PSPPS, and high-power storage facilities. The model enables us to study the possibilities of optimized dispatching of the components of the IPS of Ukraine, the limits of permissible values of parameters of generating and storing capacities, at which stable balanced operation of the energy system is possible and can be applied in the tasks of forming forecast balances covering daily schedules of electric loads to study the prospects for short- and long-term development of storage and generating capacities of the national energy system, which is relevant under conditions of rapid growth of the capacity of wind and solar power plants. The model is implemented in the mathprog algebraic modeling language, which is a component of the Solver Studio optimization package and uses the COIN-OR PuLP modeling language. Keywords: power system, daily load schedule of the power system, reserve and storage capacities, model of mathematical programming with integer variables, optimal solution

We propose a model of mathematical programming with integer variables, the use of which provides a search for the optimal modes of redundancy and loading of storage capacities of the power plants in Ukraine with covering the daily schedule of electrical loads. The main purpose of this work is to create a tool for studying the possibilities of optimized dispatching of generating capacities of thermal power plants, as well as generating and reserve capacities of high-power storage units within the IPS of Ukraine, the limits of permissible values of the parameters of generating and storing capacities, at which stable balanced operation of the energy system is possible. The model enables one to determine the optimal modes of using generating and storing capacities for covering the schedule of electrical loads without using storage and with using storage at different values of the total installed and peak power of SES and wind farms. The model takes into account the specific features of the operation of reserve and storage capacities of the Ukrainian energy system – the maximal possibilities for change in the power of storage and generation of electricity units of the Ukrainian energy system and possibility to provide support for frequency recovery reserves (secondary regulation) at a given level, located at thermal power plants, PSPPS, and high-power storage facilities. The model enables us to study the possibilities of optimized dispatching of the components of the IPS of Ukraine, the limits of permissible values of parameters of generating and storing capacities, at which stable balanced operation of the energy system is possible and can be applied in the tasks of forming forecast balances covering daily schedules of electric loads to study the prospects for short- and long-term development of storage and generating capacities of the national energy system, which is relevant under conditions of rapid growth of the capacity of wind and solar power plants. The model is implemented in the mathprog algebraic modeling language, which is a component of the Solver Studio optimization package and uses the COIN-OR PuLP modeling language. Keywords: power system, daily load schedule of the power system, reserve and storage capacities, model of mathematical programming with integer variables, optimal solution

Актуальність теми. На сьогоднішні день нерівномірний характер має попит споживачів на електричну потужність. Це призводить до зниження надійності та економічності функціонування енергосистеми, а також погіршенням якості електричної енергії. В зв’язку з цим виникає потреба в регулюванні попиту споживачів на електричну потужність. Викликало необхідність періодичного застосування адміністративних обмежень попиту споживачів на електричну енергію те, що в різні періоди часу енергетична галузь України була дефіцитною. Це пояснюється тим, що, з одного боку, на електростанціях недостатня кількість палива, а з іншого – фізична зношеність значної кількості генеруючого обладнання електростанції, а також електричних мереж. Несприятлива структура генеруючих потужностей спричинила те, що в об’єднаній системі України спостергіється серйозний дефіцит електричної потужності. Мається на увазі, що енергосистемa України недостатньо забезпечена необхiдною кількiстю маневруючих блокiв, які, в свою чергу, можуть швидко виходити нa робочий режим з горячого або холодного резервів, а також змінювати величину виробленої електричної потужності в широких межах. Тому, все більш складною задачею для української енергетичної галузі стає якість електричної енергії, а також надійність забезпечення попиту споживачів на електричну потужність. Відомо, що існують різні методи та способи керування попитом на електричну потужність, основними з яких є методи структурно-технологічного управління, адміністративно-правові методи, економічні та організаційні. Якщо розглядати структурно-технологічні методи, то мова йде про розвантаження енергосистеми при аварійних ситуаціях або дифіциті електричної потужності. Для цього було б доцільно збільшити кількість маневруючих потужностей в ОЕС України, а саме побудові нових гідроакумулюючих електростанцій, побудова та використання парогазових та газотурбінних генеруючих установок, а також модернізації існуючого обладнання ГЕС. Але, на жаль, цей шлях потребує значних фінансових та матеріальних витрат, а також достатньо тривалого часу. Тому необхідно застосовувати такі методи керування попитом споживачів на електричну потужність, які передбачають найменшу кількість витрат та часу, при цьому залишаються ефективними. Мова йде, про економічні методи керування. Таким чином, одним із таких засобів економічного керування попитом споживачів є тарифна система країни, а саме диференційовані за зонами доби тарифи. Диференційовані тарифи в Україні діють з 1995 року. В той час, використання таких тарифів мало сильний стимулюючий ефект у споживачів, при чому з кожним роком їх кількість ставала все більшою. Але, з часом, потреби споживачів на електричну енергію змінились, при чому, диференційовані за зонами доби, а саме коефіцієнти кожної зони, довгий час залишались не змінними. В зв’язку з цим, багато вчених аналізують характер впливу диференційованих тарифів на вирівнювання добових графіків, але разом з тим дана проблема залишається актуальною, адже зонні тарифи втратили свої стимулюючі ефекти до залучення нових споживачів, при чому, їх кількість, навіть, ставала меншою. Відповідно до цього було запропоновано новий спосіб адресного керування попитом споживачів на електричну потужність. Мета й завдання дослідження. Метою роботи є удосконалення механізму адресного керування попитом споживачів на електричну потужність. Для досягнення зазначеної мети були вирішені наступні завдання: • аналiз сучасного стaну eнергeтичної галузi України; • оцінка використання диференційованих за зонами доби тарифів; • визначення характеру та ступеню впливу груп споживачів на формування добового графіка електричного навантаження енергосистеми; • порівняння існуючих меж тарифних зон доби із сучасними потребами споживачів; • удосконалено концепцію та методичні основи побудови та використання мeхaніiму адресного кeрування рeжимами споживання eлeктричної потужностi; • удосконалено розрaхунок коeфіцієнту участi та коефіцiєнту рoзпoдiлу. Об’єкт дослідження. Процеси керування режимами споживання електричної потужності в енергетичній системі. Предмет дослідження. Методи та способи керування режимами споживання електричної потужності в енергетичній системі. Методи дослідження. Методи кореляційного та дисперсійного аналізу, а також математичної статистики застосовуються для визначення характеру та ступеню впливу основних груп споживачів на нерівномірність графіків електричного навантаження енергосистеми; дослідження характеру та ступеню протидії навантаження споживачів, які використовують диференційовані за зонами доби тарифи відповідно до зміни попиту на потужність споживачів, які не використовують ці тарифи; oцiнки пoтeнцiaлу eкoнoмії витрaт eнeргoсистеми на вирoбництвo електричної енергії, яку можливо отримати в результаті вирівнювання нерівномірності її графіка навантаження. Мeтoди встановлення довірчих інтервалів та групування годинних навантажень за допомогою критерія Стьюдента використовуються для виявлення фактичних зон доби зі статистично різним рівнем електричного навантаження енергосистеми та груп споживачів. Методи узагальнення та логічного підходу, методи моделювання графіків електричного навантаження, методи оптимального програмування застосовуються для використання засобу адресного керування режимами споживання електричної потужності в енергосистемі Наукова новизна одержаних результатів. Удосконалено метод визначення тривалості та меж фактичних зон доби зі статистично різним рівнем електричного навантаження, що базується на групуванні погодинних значень навантаження енергосистеми та споживачів електроенергії. Удосконалено показник, який дозволяє оцінити ступінь протидії електричного навантаження «дифтарифних» та «недифтарифних» споживачів. Визначено кількісні показники, а саме коефіцієнт участі та коефіцієнт розподілу, які дозволяють оцінити участь кожного із учасників запропонованого механізму адресного керування попитом споживачів у вирівнюванні нерівномірності графіка електричного навантаження енергосистеми. Практичне значення одержаних результатів. Для ефективного стимулювання споживачів до вирівнювання нерівномірності графіка електричного навантаження ОЕС України може бути застосовано запропоновану концепцію та методичні основи. Також, вона має новий напрямок розвитку ринкових методів керування режимами споживання електричнох потужності в енергосистемі.
Actuality of theme. To date, consumer demand for electricity is uneven. This leads to a decrease in the reliability and efficiency of the functioning of the grid, as well as the deterioration of the quality of electric energy. In connection with this, there is a need to regulate the demand of consumers for electric power. The necessity of the periodic application of administrative constraints on consumer demand for electricity was the fact that the energy sector of Ukraine was scarce at different times. This is explained by the fact that, on the one hand, there is insufficient amount of fuel at power plants, and on the other hand - physical deterioration of a significant amount of generating equipment of the power plant, as well as electric networks. The unfavorable structure of generating capacities was caused by the fact that in the united system of Ukraine there is a serious shortage of electric power. It is understood that Ukraine's energy system is insufficiently equipped with the required number of maneuvering blocks, which, in turn, can quickly enter the operating mode of hot or cold reserves, and also change the amount of electric power produced in a wide range. Therefore, the quality of electric energy, as well as the reliability of ensuring the demand of consumers for electric power, becomes an increasingly complex task for the Ukrainian energy sector. It is known that there are different methods and methods for controlling demand for electric power, the main of which are methods of structural and technological management, administrative and legal methods, economic and organizational. If we consider structural and technological methods, then we are talking about the unloading of the power system in emergency situations or the dipole of electric power. For this purpose, it would be advisable to increase the number of maneuvering capacities in the UES of Ukraine, namely the construction of new hydroelectric power stations, the construction and use of steam and gas turbine generating units, as well as the modernization of the existing equipment of the hydroelectric power station. But, unfortunately, this path requires significant financial and material costs, as well as a sufficiently long time. Therefore, it is necessary to apply such methods of controlling the demand of consumers for electric power, which provide the least amount of time and expenses, while remaining effective. It's about the economic management methods. Thus, one of such means of economic management of consumer demand is the tariff system of the country, namely tariffs differentiated by zones of the day. Differentiated tariffs in Ukraine have been in force since 1995. At that time, the use of such tariffs had a strong stimulating effect on consumers, with what each year their number became more and more. But, over time, the needs of consumers for electric energy have changed, with that, differentiated by zones of the day, namely, the coefficients of each zone, for a long time remained unchanged. In this regard, many scientists analyze the effect of differentiated tariffs on the equalization of daily charts, but at the same time, this problem remains relevant, because zone tariffs have lost their stimulating effects to attract new consumers, and at the same time, their number is even less. Accordingly, a new method of address management of consumer demand for electric power was proposed. The purpose and tasks of the study. The aim of the work is to improve the mechanism of address management of consumer demand for electric power. To achieve this goal, the following tasks were solved: • analysis of the current state of the Ukrainian energy sector; • estimation of the use of tariff-differentiated zones; • determination of the nature and degree of influence of groups of consumers on the formation of a daily schedule of electric load of the power system; • Comparison of the existing boundaries of the tariff zones of the day with the modern needs of consumers; • The concept and methodical bases of the construction and use of the mechanism of address control of electric power consumption modes have been improved; • The calculation of the participation coefficient and the distribution coefficient has been improved. Object of study. Processes of control of modes of consumption of electric power in the power system. Subject of study. Methods and methods for controlling the demand of electric power consumers in the energy system. Research methods. Methods of correlation and dispersion analysis, as well as mathematical statistics, are used to determine the nature and extent of the impact of major consumer groups on the unevenness of the schedules of the electric load of the power system; the study of the nature and degree of counteraction of the load of consumers, which use differentiated by the zones of the day tariffs in accordance with the change in demand for the power of consumers who do not use these tariffs; Estimating the potential of energy saving in electricity generation for electricity production, which can be obtained as a result of equalizing the unevenness of its loading schedule. Methods for establishing confidence intervals and clustering of hourly loads using Student's criterion are used to identify the actual days of the day with a statistically different level of electrical load of the power system and consumer groups. Methods of generalization and logical approach, methods of modeling electric power schedules, methods of optimal programming are used for the use of address management tools for power consumption in the grid. Scientific novelty of the obtained results. The method of determining the duration and limits of actual days of the day with a statistically different level of electric load, based on the grouping of hourly values of the load of the power system and consumers of electricity, has been improved. The indicator, which allows to assess the degree of counteraction to the electric load of "diffariffic" and "non-dipharmary" consumers, is improved. The quantitative indicators, namely, the coefficient of participation and the distribution coefficient, which allow estimating the participation of each of the participants in the proposed mechanism of address management of consumer demand in the alignment of the unevenness of the schedule of the electric load of the grid. The practical value of the results. For the effective stimulation of consumers to equalize the uneven schedule of electric loading of the UES of Ukraine, the proposed concept and methodical bases can be applied. Also, it has a new direction in developing market-based methods for controlling electricity consumption regimes in the grid.