Operation Of Hydroelectric Power Plants Research Articles

Methodology for Exploring Water and Hydropower Operating Criteria That Simultaneously Improve Economic and Environmental Considerations

Despite the reliability and flexibility of hydropower, the operation of hydroelectric power plants may have significant impacts on the downstream river system, including its water stage, sediment transport, and water temperature, ultimately affecting the ecology. To address these challenges, there is a need to identify water scheduling patterns that improve both hydropower economics and the environment relative to current operations. This paper presents a new methodology to explore promising operational criteria/rules that can achieve such improvements. Typical environmental impact statements and relicensing processes generally perform detailed site-specific analyses of a few alternatives that focus on reservoir water release operating rules and their associated environmental impacts. In contrast, the methodology presented in this article uses a widely applicable approach that explores a much larger solution space. This large set of potential alternatives can be represented in a multidimensional space for which one axis represents the economic value and the other axis quantify individual environmental impacts (e.g., sediment transport and fish growth), and they are explored via two approaches: a Monte Carlo simulation that identifies “win–win” alternatives and a multi-objective optimization problem that identifies Pareto-optimal alternatives.

HYDROELECTRIC PLANTS AN IMPORTANT FACTOR FOR ENERGY SECURITY / ՀԻԴՐՈԷԼԵԿՏՐԱԿԱՅԱՆՆԵՐԸ ԷՆԵՐԳԵՏԻԿ ԱՆՎՏԱՆԳՈՒԹՅԱՆ ԿԱՐԵՎՈՐ ԳՈՐԾՈՆ

Currently, a large amount of work is being done for the development of hydropower in Armenia. However, there is still a lot to be done to build new powerful plants and modernize the old ones. At the moment the Sevan-Hrazdan, Vorotan cascades and other HPPs are being operated, which provide a third of Armenia's electricity. From the point of view, it is also important to put the energy use of small water flows on the agenda. It is planned to build the Meghri and Shnogh HPPs, which will make it possible to improve the situation to some extent. The design and operation of hydroelectric power plants is of great importance for the development of Armenia's energy. It will provide an opportunity to improve the energy security of our country. The purpose of the work is to substantiate the need to build a hydroelectric power station on the Chknagh River near the city of Stepanavan in Lori Marz, RA. Methodology. The basic equations of hydraulics, as well as the basic laws of HPP design, were used in the research. Scientific novelty. It is justified that if we build a hydroelectric power station on Chknagh river, we can save 3460 tons of organic fuel per year and solve many environmental problems. Applicability. The proposal can be applied in the Lori region of the Republic of Armenia. It has been established that in case of building a hydroelectric power plant on the Chknagh River, we can save 3460 tons of organic fuel per year and improve the climatic conditions. We can produce 17.13 million kWh of electricity annually. The purchase period with investments is 10.4 years.

Analysis of the results of the study of vibrations the supporting structure of the gates of spillway structures during the operation of hydroelectric power plants

The article discusses the features of the operation of the main gates of spillway structures during the operation of the HPP. As it is known, the main spillway gates are installed at the outlet of the spillway openings into the downstream of the hydroelectric power station. The gates serve to block the openings of the spillway structure, which is opened to discharge water into a flood, as well as in the event of a disaster with an overlying hydroelectric power plant, thereby ensuring reliable operation of the entire water supply path of the hydroelectric power plant. Using the example of the Zhigulevskaya HPP, during the operation of the gates of the spillway structures, stresses in the gate structures, vibrations of the gate elements and the magnitude of the forces in the gate rod during lifting and lowering operations were determined, which made it possible to identify defects in their operation and determine recommendations for their elimination. In addition, the article discusses the results of the study of vibrations of the supporting structure of the gates of the hydroelectric power plant, which could be obtained only after identifying the features of the main gates on the spillway structures during the operation of the hydropower plant. Regarding the nature and origin of the measured oscillations, it can be said that it is not possible to give a clear explanation of the causes and physical nature of the gate oscillations at the HPP, therefore, the article considers two cases as a result of which periodic undamped gate oscillations may occur. Since it has been established that the periodic undamped oscillations registered on the gate could only be caused by a periodic disturbing force, the cause of such oscillations may be the periodic separation of vortices from the lower face of the gate. As a result, the analysis of the study of vibrations, the supporting structure of the shutter showed that the main disturbing forces for the shutter could be: pulsation of the flow pressure on the upper and lower surfaces of the shutter; dynamic forces arising when the vortices are detached from the lower face of the shutter when water flows out from under it. The article provides recommendations for avoiding vibration of the shutter in subsequent periods of operation.

Application of cross-spectral analysis and fast Fourier transform to detect soil vibrations in the natural and technical geosystem of the Dniester PSPP

The main purpose of the study is to identify the relationship between changes in water level and soil deformation, where the cyclic change in loads on the reservoir bed is the stress deviator, i.e., the PSPP reservoir acts as an oscillator of transverse vibrations, and the soil extensometer performs the function of reading and recording these vibrations. Methodology. Solution of the problem requires recording the time series of water level fluctuations and extensometer sensor fluctuations on all depth horizons. It is also necessary to perform a fast Fourier transform for water level fluctuations separately and similarly to each extensometer sensor fluctuation. We need to separately calculate the signal power spectrum of all sensors in the soil, and compare the amplitude-frequency, phase-frequency components of the power spectra of water level oscillations and vertical oscillations of the extensometer sensors. Results. During the studies, it was found that the PSPP reservoir is a source of low-frequency vibrations in a wide spectral range. These vibrations have a very long wavelength, measured in tens of thousands of kilometers, which can propagate over long distances, both along the front of geological layers and in depth. Scientific innovation. The research in this article allows us to more accurately assess the frequency spectrum of vibrations and identify possible resonance phenomena that may occur in soils during the operation of a power facility. In addition, this study was conducted in a specific region, which makes it possible to obtain more accurate data on the impact of low-frequency vibrations on the geosystem in this region. Thus, this paper may be of interest to specialists in the field of geotechnics, geology, and energy. It can also be used in the planning and operation of other power facilities in similar conditions. Practical significance. Low-frequency waves can be detected by seismic instruments such as seismometers. The results of this study will help to correct the analysis and interpretation of seismograms, which is important for understanding the processes occurring in the hydroelectric power plant operation area.

Simulator for personnel of Yumaguzinskaya HPP

During the operation of hydroelectric power plants, issues arise of improving the skills of hydroelectric power plant personnel, which can be ensured by the introduction of simulators for targeted training of personnel to work both in normal operating conditions and in pre-emergency and emergency situations as close as possible to real ones. It should be noted that the developers of simulators in the Russian energy sector peviously focused on the creation of simulators for thermal power plants, leaving hydroelectric power plants overshadowed. To date, TEST JSC has developed and implemented simulators for Irkutskaya, Bratskaya, Ust-Ilimskaya, Krasnoyarskaya, Ondskaya, Pavlovskaya and Yumaguzinskaya HPPs. This paper discusses the development for the Yumaguzinskaya HPP: a simulator with dynamic computer-aided mnemonic circuits of hydraulic units and electrical circuits of one of the Russian hydroelectric power plants, which will arouse interest among readers of the journal and potential customers. The article describes the prototype facility, the composition of the simulator, which includes a model of the facility and operating modes, a model of the control system, a model of the protection system, a model of locks, a model of emergency and warning alarms, describes in detail the educational and methodological support of the simulator complex, including models of training scenarios, an introductory model, a monitoring program, protocols and instructions. The organization of effective simulator training of operational and maintenance personnel on the simulator for operational switching of the Yumaguzinskaya HPP is achieved through the implementation in the simulator of the following main simulated subsystems: trainee's workplace model, instructor's workplace model, control object model, control system model, training system model. The hydroelectric power plant simulator presented in the paper is versatile and can find practical application both as a tool for training and examination of knowledge of operational personnel, and as a means for conducting occupational skills contests.

Relationship between the main economic, environmental and social impacts of hydroelectric dams

Hydroelectric power plants have been a growth tool to supply communities with water resources and electricity. In the last seven decades, large dams increased their environmental and social impacts, which caused the fragmentation and transformation of rivers. It is estimated that around 80 million people are displaced by its construction and operation; and its greatest impact comes from reservoirs by flooding large tracts of land permanently. In this sense, this study seeks to determine the relationship between the main economic, environmental and social impacts of the construction of hydroelectric power plants.It addresses the different non-participatory methods, such as secondary data, documents, records and databases were reviewed. From this information, principal component analysis, simple regression, correlations, multivariate and 3D dispersion graphs were performed. Once the different methods were applied, a significant correlation was identified between the variables of installed capacity and number of displaced people. The study concludes that natural resources are a source of attraction for people to settle around them, the water resource is of special interest, therefore, it is not strange that when establishing a hydroelectric project, there is invariably displacement of people in order to benefit a greater number of them through the generation of energy, prevent floods and droughts among other benefits, depending on the category that the dam have, as there are single purpose and multiple purpose. It is undeniable that there is a very strong correlation between the construction of dams and the economic development of a region, however, the correlation that exists between the construction of dams and the displacement of people is also undeniable, hence the importance of this study that is presented, since it allows having clearer economic, environmental and social perspectives that allow identify whether large hydroelectric project construction projects succeed or fail in their purpose of sustainable regional development.The results indicate that by increasing the installed capacity, there is a social impact as it will increase the displacement of people due to the construction or operation of hydroelectric power plants.

Energy and economic study of the increased energy production of cascaded hydroelectric plants due to the heightening of the upstream reservoir: A case study in Cipó-Rio das Antas dam

Increased hydroelectric reserve capacity through cascade heightening is one option for increasing its overall output. Such increases are relevant to the circumstances faced by the Brazilian energy matrix, which is heavily dependent on hydroelectric dams and where many environmental restrictions may slow the construction of new dams. Thus, this article studies the increase in storage volume in a Brazilian dam and evaluates the gains in terms of electricity generation and water flow on downstream dams. A dam located on the Antas River, in Brazil, was chosen as the study area. Flow regulation capacity from the increased height was determined through multiple hydrological methods which enabled the estimation of energy gains on downstream dams. The results obtained demonstrate that, by increasing the dam height by 1 m to the upstream structure, there would be a regularized flow of 2.47 m3/s along with an increase in energy production of 3.34 GWh/y throughout the entire downstream cascade. Investments of 500,000 USD would be necessary to add an additional meter to the dam construction height, which would be paid off over a period of five years with the increase in energy production. The methodology herein presented can be replicated in other regions, thus aiding in greater efficiency and operation of hydroelectric power plants.

ზედა საფეხურის წყალსაცავის სამუშაო რეჟიმების შერჩევა, ქვედა ბიეფის ჰესების ეფექტური ფუნქციონირების გათვალისწინებით, რიონის ჰესების მაგალითზე

Efficient management of renewable energy sources, including water resources in the context of global warming and tightening environmental requirements, is the most important challenge of our time. Territorial and temporal redistribution of river runoff within the catchment area is essential for energy reservoirs. The regulation of the river runoff by the reservoir which ensures the operation of hydroelectric power plants located in the downstream with high energy performance is discussed. In particular, the selection of the operating modes of the Lajanuri reservoir (upper stage) is presented taking into account the efficient operation of the downstream HPPs (Gumati HPP I, Gumati HPP II, Rioni HPP). The calculations were made for the case of daily regulation of Lajanuri reservoir. At the same time, the one-stage (peak regime) and the two-stage (peak and base regimes) regulation types are discussed. The water balance equation was used for calculations. Based on the results of calculations, it is advisable to operate the Lajanur reservoir in a two-stage mode, which will increase the peak power of the HPP in a dry watery period at the increased power consumption.

Effects on Fluvial Geomorphology and Vegetation Cover following Hydroelectric Power Plant Operation: A Case Study in the Maule River (Chile)

The installation of hydroelectric plants has generated multiple environmental impacts on the world’s river systems. In central Chile, the impacts of hydroelectric reservoir operation have been documented in ecological and hydrologic regime terms. This investigation assesses the changes in channel morphology, vegetation distribution, and flows in the middle section of the Maule River during the period following the start-up of a hydroelectric plant. Changes in fluvial morphology (active area) and land cover are quantified using LANDSAT images, contrasted with a vegetation sampling and flow analysis. The results show a 12% decrease in active areas of the river, indicating a loss of geomorphological diversity. Within the active channel, there was a gradual increase in plant-covered surface area, which reached 159% between 1989 and 2018, mainly due to reductions in water (−61%), active bar (−35%), and bare soil surface areas (−29%). The changes were evident ten years after plant operations began and intensified during the period known as the megadrought in central Chile (2008–2018). The flow magnitudes present a decrease for exceedance probabilities (P) below 85% in the period after 1985, with a slight increase recorded for low flows (P > 85%). In the segments with superior stabilization, invasive species such as Acacia dealbata (silver wattle) predominated, which are specialists at taking advantage of disturbances to settle and stabilize active areas, narrowing the possibilities for morphological change.

Influence of frequency and power control modes on the technical condition of hydraulic units of hydroelectric power plants

The features of the operation of hydroelectric power plants, which are used to regulate the frequency and power in the power system with a wide range of load variations and with varying degrees of intensity of operation mode variations, are considered. An approach is proposed to assess the impact on the reliability of hydraulic turbine equipment used in these modes. When examining the equipment of existing hydroelectric power plants, it has been revealed that the mode of automatic secondary regulation of frequency and power flows in the power system has the greatest impact on the technical condition of hydraulic turbines. Intense participation in regulation leads to an increase in dynamic loads on the hydraulic unit, loads on the friction pairs of the regulating elements of the turbine compared to the basic, semipeak and peak modes and leads to additional wear, reduced reliability and deterioration of the technical condition of the equipment. The operation in the automatic secondary regulation mode of hydraulic units at different HPPs differs depending on the function performed in the power system. To determine the loading of a hydraulic unit with transient load variation modes during operation in the mode of automatic secondary regulation of frequency and power flows, it is proposed to introduce a parameter characterizing the intensity of operation of hydraulic units of HPP in the aforesaid mode and to take it into account in order to accumulate data on the actual operating modes of hydraulic units and use it in assessing and predicting the technical condition of equipment.

Quantifying the impacts of climate variation, damming, and flow regulation on river thermal dynamics: a case study of the W\u0142oc\u0142awek Reservoir in the Vistula River, Poland

BackgroundRiver damming inevitably reshapes water thermal conditions that are important to the general health of river ecosystems. Although a lot of studies have addressed the damming’s thermal impacts, most of them just assess the overall effects of climate variation and human activities on river thermal dynamics. Less attention has been given to quantifying the impact of climate variation, damming and flow regulation, respectively. In addition, for rivers that have already faced an erosion problem in downstream channels, an adjustment of the hydroelectric power plant operation manner is expected, which reinforces the need for understanding of flow regulation’s thermal impact. To fill this gap, an air2stream-based approach is proposed and applied at the Włocławek Reservoir in the Vistula River in Poland.ResultsIn the years of 1952–1983, downstream river water temperature rose by 0.31 ℃ after damming. Meanwhile, the construction of dam increased the average annual water temperature by 0.55 ℃, while climate change oppositely made it decreased by 0.26 ℃. In addition, for the seasonal impact of damming, autumn was the most affected season with the warming reached 1.14 ℃, and the least affected season was winter when water temperature experienced a warming of 0.1 ℃. The absolute values of seasonal average temperature changes due to flow regulation were less than 0.1 ℃ for all the seasons.ConclusionsThe impacts of climate variation, damming, and flow regulation on river water temperatures can be evaluated reasonably on the strength of the proposed methodology. Climate variation and damming led to general opposite impacts on the downstream water temperature at the Włocławek Reservoir before 1980s. It is noted that the climate variation impact showed an opposite trend compared to that after 1980s. Besides, flow regulation below dam hardly affected downstream river water temperature variation. This study extends the current knowledge about impacts of climate variation and hydromorphological conditions on river water temperature, with a study area where river water temperature is higher than air temperature throughout a year.

РЕАКЦІЯ БАГАТОРУКАВНИХ РІЧКОВИХ СИСТЕМ НА ФУНКЦІОНУВАННЯ ГІДРОЕЛЕКТРОСТАНЦІЙ

The operation of the hydroelectric power plant is one of the main reasons for the transformation of river runoff. The change in the hydrological regime affects several other processes taking place in the river channel, including the transformation of its geomorphological features. The article presents the impact of the Kaniv and Włocławek dams on the hydrological regime of the middle Dnieper River and the lower Vistula River. The nature and magnitude of changes in the Dnieper and The Vistula rivers flow regime caused by the functioning of the dams were determined using IHA (Indicators of Hydrologic Alteration) and the RVA (The Range of Variability Approach) method. It was demonstrated that the operation of the hydroelectric power plant especially in the hydropeaking system is the cause of a large flow alteration in respect of the frequency and duration of low- and high-flow pulses and the rate and frequency of change in the flow. It was assessed how the change in flow conditions in connection with the deficit of sediments affected the transformation of the Vistula and Dnieper river channels downstream of the dams. Based on our results, the reaction of the fluvial system to changes in the flow regime caused by the operation of the Kaniv and Włocławek hydroelectric power plants consisted in: 1) changing the width and depth of channels; 2) changing the size of the forms separating channels; 3) fixation of the anastomosing fluvial system. More dynamic water flows due to the operation of hydroelectric power plants modify and dynamize the natural process of evolution of a fluvial system into an anastomosing system by causing the incision and narrowing of the main channels, because of which the side channels occupy a higher position above them. On the other hand, the equalization of the water flow in the channels causes a decrease in the water level and the disappearance of the flow in the side channels. As a result, the islands separated by these channels merge and inter-channel areas are formed.

ОСОБЕННОСТИ ВОДОЭНЕРГЕТИЧЕСКИХ РЕЖИМОВ ГЭС ПРИ СИМБИОЗЕ С ГЕЛИОУСТАНОВКАМИ

The results of the analysis of the problems associated with the development of the world solar energy are presented. It is noted that at the present stage of the electric power industry, the potential of renewable energy sources (RES) is still poorly realized. The specific issues of water-energy modes of operation of hydroelectric power plants (HPPs), operating in symbiosis with solar photovoltaic installations (SPEU) have been identified, the schedule of which should be the same. It is shown that the operation of hydroelectric power plants and SPEU in the joint electric load schedule makes it possible to obtain a constructive and economic effect due to the fuel saving of power plants of various types, including thermal ones. The maximum capacity of the HPP-SPEU power complex is optimized by the installed capacity of the HPP while observing the full duplication of the SPEU capacity by other power plants of the energy system. It is shown on the example of the Lagdo hydroelectric complex in the northern Cameroon that under the conditions of developing countries with a large solar and hydraulic potential (Cameroon, Zimbabwe, Uganda, etc.), as well as for the southern regions of Russia, SPEU can produce up to 75% of the annual electricity generation during the low-water period of the year at its joint work in the energy complex with the hydroelectric power plant. This makes it possible to facilitate the redistribution of the river fl ow during the entire low-water period without attracting additional useful storage capacity of the reservoir. The developed methodology for optimizing the water-energy regulation regime can also be applied during the operation of the HPP of the HPP-SPEU energy complex along the watercourse, i.e. with daily flow regulation.

Strategic Operation of Hydroelectric Power Plants in Energy Markets: A Model and a Study on the Hydro-Wind Balance

The European Union defined ambitious targets for the production of energy from renewable energy sources. Most European markets trade now high levels of variable renewable energy (VRE). Renewable generation increases the variability and uncertainty of the net-load (i.e., demand minus VRE). To a large extent, this variability and uncertainty can be compensated by hydroelectric power plants. Typically, hydro power producers (HPPs) consider the periods of time with low market prices (and normally low demand and/or high VRE production) to pump, and the periods with high market prices (and normally high demand and/or low VRE production) to produce energy. This article presents a model for hydro power plants and a study to analyse the hydro-wind balance in a real-world setting, namely a simplified version of the Portuguese power system, involving a significant penetration of hydro and wind power (more than 50%). The study is conducted with the help of the multi-agent system MATREM. The results confirm (and rebut) the typical behavior of hydroelectric power plants (to produce energy, to pump water or to stay idle).

Modern problems of state regulation of operation of a large hydroelectric plants dams area

The article is devoted to the problem of increasing the risk of accidents at the dam areas of a large power plant (HPP) and the surrounding area over time, and the need to take these risks into account during their operation. The purpose of the research is to introduce the concept of a dam area as an object of state regulation, to reveal the ways of development and legislative solution of the problem of safe operation of hydroelectric power plants and dam territories at the Federal level, and to develop recommendations for their state regulation. The paper shows the necessity and expediency of zoning the dam territory according to the degree of dynamic impact of the HPP on it in order to optimize the administrative and economic consequences of the operation of these objects.

Определение показателей работы гидроэлектростанций с учетом ограничений на выдачу мощности по системным условиям

The aim of the study is to evaluate the extent to which the generating capacities of hydroelectric power plants (HPPs) are underutilized during their joint operation with thermal power plants (TPPs) in a grid under high water conditions. The data on constraints imposed on the operation of power plants in different periods of time for determining their operation intervals were studied based on reported information on the market operation modes for a day ahead. The analysis was carried out for joint operation of HPPs and TPPs in years characterized by different abundance of water resources. Data for the Interconnected Power System of Siberia and two typical periods, namely, an average working day in January and an average working day in June were taken as an analysis example. For each of the considered HPPs, their initial participation was made in the grid load curve: in the load curve base part according to the above-mentioned base part and the HPP monthly average power, and in the load curve peak part according to monthly average and working power (minus their operation in the load curve base part). The participation of the HPPs was determined taking into account the technical and technological minimums of TPP operation. The procedure of determining the participation of power plants is iterative in nature and uses the method of golden section for selecting the parameters characterizing the power plant participation in the load curve and the power capacity margin. It follows from the obtained results that in January, the limitations relating to the TPP operation mode impose no constraints on the operation of HPPs. However, in the June load curve, in which the influence of water abundance on the HPP operation mode is much more significant due to the HPP operational requirements, the HPSs cannot operate at their full capacity; that is, the extent to which the HPP capacity is underutilized depends on the water abundance in a year. By using the developed algorithm, it is possible to estimate the amount of HPP generating capacity underutilized in an interconnected power system. The underutilized power generation capacity of the Angara-Yenisei HPP chain in the Interconnected Power System of Siberia can be used for generating and transmitting power to the European part of the UES of Russia, e.g, to compensate the insufficient output of HPPs in the Volga-Kama chain during low water periods.

Russian hydropower under the global climate change

The influence of the climate change in Russia on the operation of hydroelectric power plants during the 21st century is considered. For obtaining quantitative assessments, the results yielded by global climatic models for river runoff were subjected to ensemble averaging. In addition to the standard RCP climatic scenarios, the MPEI scenario is considered, the fundamental distinctive feature of which is that the most likely development trajectories are selected. It is found that the choice of a scenario has an essential effect on both the qualitative pattern of river runoff changes over the territory and on the quantitative characteristics of this process.An integral assessment for the change in the hydroelectric power plant outputs due to climate change is made.

Russian Hydropower under the Global Climate Change

The influence of the climate change in Russia on the operation of hydroelectric power plants during the 21st century is considered. For obtaining quantitative assessments, the results yielded by global climatic models for river runoff were subjected to ensemble averaging. In addition to the standard RCP climatic scenarios, the MPEI scenario is considered, the fundamental distinctive feature of which is that the most likely development trajectories are selected. It is found that the choice of a scenario has an essential effect on both the qualitative pattern of river runoff changes over the territory and on the quantitative characteristics of this process.An integral assessment for the change in the hydroelectric power plant outputs due to climate change is made.

К оценке состояния гидротехнических сооружений гидроузлов в современных условиях

The effect the limitations imposed on the water storage reservoir’s headrace level (HRL) variation rate have on the hydroelectric power plant (HPP) power performance indicators is studied taking the cascade of Yenisei HPPs as an example. For quantitatively determining the effect the limitations imposed on the Sayano-Shushenskaya HPP’s HRL variation rate (depending on the air temperature in the preceding period) have on the HPP power performance indicators, water energy calculations were carried out for the following Yenisei cascade operation scenarios: operation of the Sayano-Shushenskaya HPP with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period; operation of the Sayano-Shushenskaya and Krasnoyarsk HPPs with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period. The mean energy capability (E0) and the guaranteed power output in winter (Nguar) were taken as the HPP performance indicators from which the effect of limitations was estimated. As a result of the accomplished computations, the guaranteed winter power output in the Sayano-Shushenskaya hydropower system decreased by 17.37%, and its mean energy capability decreased by 3.29%. Based on the accomplished water-energy calculations, a new (corrected) operating mode of the Sayano-Shushenskaya HPP was obtained, in which the regime of levels did not escape beyond the temperature-related limitations. The changes in the Sayano-Shushenskaya HPP operation mode led to a change in the HPP tail race flows. As a result, the Krashoyarsk HPP operation mode was also changed due to the new inflow regime to its site. The study results show very clearly that application of environment temperature-related limitations on the Sayano-Shushenskaya HPP hydraulic structures directly affects the power performance indicators of the Krasnoyarsk HPP. The strongest effect on the Krasnoyarsk HPP parameters takes place at the average temperature in the Karlov site from –17 °С to –11.8 °С in winter and from +8.5 °С to +11 °С in summer. This is connected with the Sayano-Shushenskaya HPP HRL variation rate limitation curve pattern, which in its turn entails a decrease in the HPP tail race flow and, as a consequence, a decrease in the total inflow to the Krasnoyarsk HPP site. As regards the temperature range at the Krasnoyarskaya HPP site, it is from –20 °C to –11 °C for the winter period and from +5 °C to +8 °C for the summer period. The difference in the mean energy capability and guaranteed power output of the Krasnoyarsk HPP during operation under the above-mentioned conditions is 12.9% for mean energy capability and 13.7% for guaranteed winter power output. Key words: limitation of water level variation rate in a water storage reservoir, change of power performance parameters, cascade of Yenisei HPPs.

К оценке состояния гидротехнических сооружений гидроузлов в современных условиях

The effect the limitations imposed on the water storage reservoir’s headrace level (HRL) variation rate have on the hydroelectric power plant (HPP) power performance indicators is studied taking the cascade of Yenisei HPPs as an example. For quantitatively determining the effect the limitations imposed on the Sayano-Shushenskaya HPP’s HRL variation rate (depending on the air temperature in the preceding period) have on the HPP power performance indicators, water energy calculations were carried out for the following Yenisei cascade operation scenarios: operation of the Sayano-Shushenskaya HPP with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period; operation of the Sayano-Shushenskaya and Krasnoyarsk HPPs with variable limitations imposed on the HRL variation rate depending on the air temperature in the previous period. The mean energy capability (E0) and the guaranteed power output in winter (Nguar) were taken as the HPP performance indicators from which the effect of limitations was estimated. As a result of the accomplished computations, the guaranteed winter power output in the Sayano-Shushenskaya hydropower system decreased by 17.37%, and its mean energy capability decreased by 3.29%. Based on the accomplished water-energy calculations, a new (corrected) operating mode of the Sayano-Shushenskaya HPP was obtained, in which the regime of levels did not escape beyond the temperature-related limitations. The changes in the Sayano-Shushenskaya HPP operation mode led to a change in the HPP tail race flows. As a result, the Krashoyarsk HPP operation mode was also changed due to the new inflow regime to its site. The study results show very clearly that application of environment temperature-related limitations on the Sayano-Shushenskaya HPP hydraulic structures directly affects the power performance indicators of the Krasnoyarsk HPP. The strongest effect on the Krasnoyarsk HPP parameters takes place at the average temperature in the Karlov site from –17 °С to –11.8 °С in winter and from +8.5 °С to +11 °С in summer. This is connected with the Sayano-Shushenskaya HPP HRL variation rate limitation curve pattern, which in its turn entails a decrease in the HPP tail race flow and, as a consequence, a decrease in the total inflow to the Krasnoyarsk HPP site. As regards the temperature range at the Krasnoyarskaya HPP site, it is from –20 °C to –11 °C for the winter period and from +5 °C to +8 °C for the summer period. The difference in the mean energy capability and guaranteed power output of the Krasnoyarsk HPP during operation under the above-mentioned conditions is 12.9% for mean energy capability and 13.7% for guaranteed winter power output. Key words: limitation of water level variation rate in a water storage reservoir, change of power performance parameters, cascade of Yenisei HPPs.