Operation Of Hydroelectric Plants Research Articles

Operation of hydroelectric plants without storage volume due to optimization of the turbine flow

Hydroelectric power plants in diversion scheme systems utilize the water flowing through the river, since they present the necessary facilities and infrastructures to channel and harness the water, without having in their initial conception any storage systems. This type of power stations are designed and automated to operate between certain limits of water head, working with “constant head”, using the heads available at any moment. The operating limits are determined by the “nominal flow” for which the power plant has been designed and the “minimal technical flow” which corresponds to the minimum value of the flow with which the plant can work, which depends on each type of turbine. By means of the presented optimization algorithms we can take advantage of those periods of time with low levels of flow (low water levels) to utilize the channels in the power station as storage elements of flow under the technical minimum, making the power plant undergo sequential cycles of emptying/filling of channels, allowing for the energetic exploitation, that will be denoted as “optimal flow”.In this article, we intend to determine how we can adapt each type of turbine to the new optimization algorithms proposed, establishing the increments in production obtained for each type of turbine and the possibility of applying the “optimal flow" algorithms.

The climate change potential effects on the run-of-river plant and the environmental and economic dimensions of sustainability

In this work, we evaluate the environmental and economic sustainability dimensions of a run-of-river hydroelectric plant operation regarding environmental impacts and potential direct and indirect effects of climate change. Results suggest the generation of a vicious cycle of clean generation and dirty generation, enhanced by a positive feedback with climate change impacts. This cycle is triggered by the tradeoffs between environmental protection policies and the socioeconomic pressure for energy production, embedded in an energy production matrix that prioritizes fossil fuel-based production as responses to peak energy demand. The climate projections were generated by the Eta Regional Climate Model from the National Institute for Space Research. They were forced by the atmospheric simulations of the Interdisciplinary Climate Research Model (MIROC5) and the Hadley Center Global Environmental Model (HadGEM2-ES) under the RCP4.5 and RCP 8.5 emission scenarios. The MHD-INPE Distributed Hydrological Model was used to generate streamflow projections. Environmental impacts were assessed by accounting for carbon stock and sequestration, greenhouse gas emissions, and energy cost. Climate projections indicated reduced precipitation and increased temperature. The streamflow will present progressively reductions of the flow volume until the end of the century, which undermines the plant's ability to ensure firm energy and induce thermal plants' activation to supply the demand. This activation will lead to an increase in greenhouse gas emissions and an increase in the price of energy, which may lower the benefits in carbon stock associated with a run-of-river hydropower plant and negatively influence the reduction commitments assumed by Brazil.

EXPANDING THE CONCEPT OF PEOPLE AFFECTED BY HPP: JIRAU AND PENHA VILLAGE SETTLEMENTS - RONDÔNIA

Abstract This work seeks to discuss the conception of affected and the reconfiguration of the territory and social lives with the observation and analysis of two communities not considered affected by the Jirau HPP: that of the small Village Jirau and Village of the Penha. The research is characterized as theoretical-descriptive, based on the issues related to the territory of occurrence of impacts of the construction and operation of hydroelectric plants, and fieldwork was performed with non-participant observation, the data were compiled from the perception of the researchers and allow us to conclude that the damage of the construction of the HPP, in these communities, put them in a condition of being affected , the impact happens in the territory as a result of the influence and confluence of the networks of life lived, comprising the river and what relates it, the connecting roads, the networks of housing.

Security of power supply in hydrothermal systems: Assessing minimum storage requisites for hydroelectric plants

Unfavorable hydrological conditions experienced from 2014 to 2019 led to the depletion of main reservoir systems in Brazil, causing an increase of thermal energy dispatch. However, an important share of the observed thermal generation was out of economic merit, commanded by government entities which risk perception relies mainly on experts’ tacit knowledge. Despite the common sense that storage in reservoirs is intrinsically linked to system security, the metrics employed so far failed to compute the system’s real needs in terms of required stored energy in hydroelectric plants. This work proposes a new method to evaluate the security of power supply in systems with predominance of hydroelectricity, by the development of an optimization model that assesses the minimum secure levels for hydroelectric plants operation in each month, from a nonlinear-backward simulation of 88 historical streamflow series (1931–2018). In addition, based on the simulation results, two reference curves were suggested for the continuous monitoring of the reservoirs operation, with the purpose of subsidizing Brazilian government entities decisions on unorthodox thermal generation dispatch. The monitoring of the proposed reference curves is expected to represent a more robust criterion for decisions on out-of-merit thermal generation in Brazilian power system.

A Reservoir Operation Policy Using Inter-Basin Water Transfer for Maximizing Hydroelectric Benefits in Brazil

The Hydrothermal Coordination problem consists of determining an operation policy for hydroelectric and thermoelectric plants within a given planning horizon. In systems with a predominance of hydraulic generation, the operation policy to be adopted should specify the operation of hydroelectric plants, so that hydroelectric resources are used economically and reliably. This work proposes the implementation of reservoir operation rules, using inter-basin water transfer through an optimization model based on Network Flow and Particle Swarm Optimization (PSO). The proposed algorithm aims to obtain an optimized operation policy of power generation reservoirs and consequently to maximize the hydroelectric benefits of the hydrothermal generation system, to reduce the use of thermoelectric plants, the importation and/or energy deficit and to reduce the cost associated with meeting the demand and reduce CO2 emissions from combustion of fossil fuels used by thermoelectric plants. In order to illustrate the efficiency and effectiveness of the proposed approach, it was evaluated by optimizing two case studies using a system with four hydroelectric plants. The first case study does not consider transfer and water and the second case study uses water transfer between rivers. The obtained results illustrate that the proposed model allowed to maximize the hydroelectric resources of a hydrothermal generation system with economy and reliability.

Evaluating effects of dam operation on flow regimes and riverbed adaptation to those changes

The operation of dam and reservoirs is one of the main reasons for the transformation of river runoff. The change in the hydrological regime affects a number of other processes taking place in the river channel, including the transformation of its geomorphological features. The article presents the impact of the Włocławek Reservoir on the hydrological regime of the lower Vistula. The alterations of the river flow downstream of the dam in the conditions of the hydropeaking regime of hydroelectric plant operation and after its change to the run-of-river and interventional operation were characterised. It was assessed how the change in flow conditions in connection with the deficit of sediments affected the transformation of the Vistula river channel downstream of the dam. The nature and magnitude of changes in the Vistula river flow regime caused by the functioning of the “Włocławek” dam 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 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. The change in the manner of operation of the hydroelectric power plant affected the reduction in the degree of transformation of most features of the flow. The increase in water erosion force downstream of the dam led to the deepening and narrowing of the river channel. The presence of more resistant formations at the bottom of the river channel inhibited riverbed erosion, at the same time intensifying lateral erosion, which increased the width of the river channel. During the operation of the reservoir, the river channel downstream of the dam evolved towards the anabranching type system.

Assessment of the Demarcation Method for Federal Riverine and Accreted Lands: Case Study of the Rio De Janeiro State Section of the South Paraíba River

This study analyzes the demarcation method of riverine and accreted land of the Brazilian Federal Heritage Department and proposes the incorporation of the flow rate corresponding to the recurrence interval of two years, as recommended by the State Environmental Institute of the state of Rio de Janeiro. The case study of the Rio de Janeiro section of the Paraiba do Sul River was investigated, and the results indicate that the Federal Heritage Department’s method does not consider the ongoing anthropization of the river, caused mainly by the construction and operation of hydroelectric plants. In addition, it was observed that the limnimetric scales of the studied gauging stations are influenced by constant changes in the riverbed and by riverbank occupation, making it difficult to estimate the ordinary flood level. The study concludes by suggesting the adoption of a flow rate with a recurrence interval of two years and the simulation of the runoff conditions for demarcation of the average ordinary flood line.

Biomarkers and bioindicators of the environmental condition using a fish species (Pimelodus maculatus Lacepède, 1803) in a tropical reservoir in Southeastern Brazil.

The Funil Reservoir receives a large amount of xenobiotics from the Paraíba do Sul River (PSR) from large number of industries and municipalities in the watershed. This study aimed to assess environmental quality along the longitudinal profile of the Paraíba do Sul River-Funil Reservoir system, by using biomarkers and bioindicators in a selected fish species. The raised hypothesis is that Funil Reservoir acts as a filter for the xenobiotics of the PSR waters, improving river water quality downstream the dam. Two biomarkers, the ethoxyresorufin-O-deethylase activity (EROD), measured as fluorimetricly in S9 hepatic fraction, and the micronuclei frequency (MN), observed in erythrocytes of the cytoplasm, and three bioindicators, the hepatosomatic index (HSI), gonadosomatic index (GSI) and condition factor (CF) were used in Pimelodus maculatus, a fish species widely distributed in the system. Four zones were searched through a longitudinal gradient: 1, river upstream from the reservoir; 2, upper reservoir; 3, lower reservoir; 4, river downstream of the reservoir. EROD activity and HSI and GSI had significant differences among the zones (P<0.05). The upper reservoir had the lowest EROD activity and HSI, whereas the river downstream of the reservoir had the highest EROD and lowest GSI. The river upstream from the reservoir showed the highest HSI and GSI. It is suggested that the lowest environmental condition occur at the river downstream of the reservoir, where it seems to occur more influence of xenobiotics, which could be associated with hydroelectric plant operation. The hypothesis that Funil reservoir acts as a filter decanting pollution from the Paraíba do Sul River waters was rejected. These results are novel information on this subject for a native fish species and could be useful for future comparisons with other environments.

Método para Calcular Políticas de Operación a Largo Plazo de Sistemas Hidroeléctricos de Potencia en el Contexto del Cambio Climático

El propósito de este trabajo es presentar un método de optimización para el cálculo de políticas de operación cuasi-óptimas robustas de sistemas hidrotérmicos de potencia (SHTP). Por política óptima se entiende una de menor costo, y por robusta aquella que a pesar de variaciones en el caudal afluente al reservorio produce un número de fallas menor o igual que 10%. Como caso de estudio, el método se aplicó a un SHTP con central hidroeléctrica de características similares a la de Paute. Dicho procedimiento constituye una variación del método de las partículas, y consiste de dos fases: en la primera se calcula una política óptima correspondiente al promedio de los caudales afluentes al reservorio de la central, y en la segunda se busca su vecindad otra que además sea robusta. En ambas fases se realizan búsquedas mediante algoritmos genéticos. A fin de considerar los efectos del cambio climático se utilizaron horizontes de 30 años. Este método constituye una herramienta útil para estimar políticas cuasi-optimas robustas en la operación de largo plazo de centrales hidroeléctricas. Además, podría utilizarse para dimensionar correctamente el tamaño de reservorios de sistemas en fase de planificación. Inicialmente, al aplicar el método propuesto al caso de estudio no se obtuvieron políticas cuasi-óptima robustas, lo que no sorprende pues su central hidroeléctrica tiene características que corresponden a una de paso. Sin embargo, al incrementar las dimensiones del reservorio, entonces sí se encontraron varias soluciones con las características deseadas. Será el administrador del sistema quien finalmente decida cual aplicar.

Hybrid Model for Short-Term Scheduling of Hydropower Systems

In this paper the authors propose a global–local methodology for optimizing the short-term operation of hydroelectric plants. The authors determine the tradeoffs between minimizing the daily release from the plant and minimizing the number of startups and shutdowns of the generating units. The model is formulated as a mixed integer, nonlinear programming optimization problem with multiple objectives. The authors consider the nonlinearities of the generating units without simplifications or approximations. The authors develop a solution method that combines an evolutionary algorithm for the global search of the integer variables and a gradient-based local optimizer for the continuous variables. The local optimizer is embedded in the global search algorithm. Convergence is achieved by iterating between the global search and the local optimizer. The proposed methodology is applied to a moderately sized Brazilian hydroelectric plant that belongs to the national interconnected system. Additionally, a comparative study was conducted using historical operational records. The results demonstrate that the proposed methodology is feasible for online daily operations and delivers two specific benefits. The first is the efficiency gained, as the model seeks to operate the generating units as close as possible to their most efficient operating points. The second benefit is reduction of the units’ maintenance costs, as the model minimizes switching on/off of the generating units.

Modelagem e Simulaçao do Escoamento e Dispersão Sazonais de Agentes Passivos no Rio Araguari AP: Cenários para o AHE Ferreira Gomes-I-Amapá/Brasil

The research seeks to model and simulate the hydrodynamic and dispersion phenomena in water applied to environmental impact assessment (EIA) for the construction of the Ferreira Gomes I hydroelectric plant (AHE), located in the middle Araguari river - Amapa, Brazil. The general objective is to analyze the changes in river flow behavior as an abiotic factor in deciding the new balance of the aquatic ecosystem of the future reservoir. Besides flow, the physical processes that involve the dispersion of passive agents in water are analyzed. They are specifically represented by continuous inert loads prior to and after construction of the reservoir. The methodology involved the use of an CFX 11.0 computer system to model and simulate the turbulent flow numerically. The turbulence model used was the standard model k-e. 3D computational meshes were generated to represent the geometry of the water system before and after construction of the reservoir. Environmental scenarios were used in four different steady seasonal streamflows: maximum, average, minimum and ecologic. The results indicated a significant change in both the geometric characteristics of the natural channel and in the hydrodynamic behavior of the pollution plumes in water. It was found that the seasonal hydrologic drought may be most critical to control the amount of flow at Ferreira Gomes I AHE, especially as a consequence of the Coaracy Nunes (UHCN) hydroelectric plant operation. In conclusion it was observed that the environmental scenarios show the importance of studying the hydrodynamic flow regime, especially the minimal and ecologic flows, because the dispersion processes of the passive agents in water are critical and strongly linked with the maintenance of ecological and biogeochemical cycles (renewal rate, reaeration, flow regime: lotic or lentic). The results indicate the usefulness of applying objective methods to represent the complex flo

Characterization of water quality in a small hydropower plant reservoir in southern Brazil

AbstractThe construction of large reservoirs can cause profound environmental changes. Reduced water flow, increased water residence time, thermal stratification, increased sedimentation rates and decreased dissolved oxygen concentrations are examples of such changes. These changes can affect water quality and the biota in the environments adapted to the natural conditions of a river. Small reservoirs developed in conjunction with hydropower plants, however, could reduce the degraded water quality. This study focuses on characterizing water quality in a small hydroelectric reservoir. The study reservoir has an area of 1.4 km2 and a short water retention time. The Monte Claro Hydroelectric Power Plant is part of a complex consisting of three plants on the Antas River in the north‐west of Rio Grande do Sul state, Brazil. The reservoirs associated with these plants are operated as run‐of‐the‐river facilities. Monitoring results obtained by CERAN, the Energetic Company of Antas River (Companhia Energética Rio das Antas), were used to evaluate the reservoir water quality. Three samples were collected seasonally (spring, summer, autumn and winter) in the area of influence of this plant following the filling of the reservoir (2005–2008). The examined water quality parameters were electrical conductivity, colour, turbidity, alkalinity, pH, biological oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus, dissolved oxygen, sulphate, nitrate, nitrite, ammonia, suspended and dissolved solids, chlorophyll‐a, total and faecal coliforms, water temperature and Secchi depth transparency. The results were interpreted using an index of water quality, Trophic State Index, reservoir water quality and CONAMA Regulation 357/05 (Brazilian legislation). Based on these analyses, no significant changes were exhibited in the water quality of the reservoir from the hydroelectric plant operation.

An improved PSO approach to short‐term economic dispatch of cascaded hydropower plants

PurposeThe purpose of this paper is to establish the optimization model and solve the short‐term economic dispatch of cascaded hydro‐plants.Design/methodology/approachAn improved particle swarm optimization (IPSO) approach is proposed to solve the short‐term economic dispatch of cascaded hydroelectric plants. The water transport delay time between connected reservoirs is taken into account and it is easy in dealing with the difficult hydraulic and power coupling constraints using the proposed method in practical cascaded hydroelectric plants operation. The feasibility of the proposed method is demonstrated for actual cascaded hydroelectric plant.FindingsThe simulation results show that this approach can prevent premature convergence to a high degree and keep a rapid convergence speed.Research limitations/implicationsThe optimal values of parameters in the proposed method are the main limitations where the method will be applied to the economic operation of the hydro‐plant.Practical implicationsThe paper presents useful advice for short‐term economic operations of the hydro‐plant. A new optimization method to solve the short‐term optimal generation scheduling is proposed. The optimal generation power and water discharge during the whole dispatching time for hydro‐plant operation can be obtained.Originality/valueThe IPSO method is realized by maintaining high diversity of the swarm during the optimization process and preventing premature convergence.

Influence of pumped-storage hydroelectric plant operation on a shallow polymictic lake: Predictions from 3-D hydrodynamic modeling

Pumped-storage hydroelectric plants play important roles in electrical supply grids by providing electricity during periods of peak demand, storing renewable energy and controlling supply frequency. The pumping of water from a lower lake or reservoir to an upper impoundment and the return of that water during power generation can strongly affect the properties of pumped-storage reservoirs, however. For example, plant operation has been found to delay, weaken or eliminate thermal stratification, resuspend bottom sediments and entrain organisms. The aim of this study was to better understand the impacts of a proposed pumped-storage facility on stratification, mixing and sediment resuspension in Lake Elsinore, a shallow, polymictic lake in southern California. Three-dimensional hydrodynamic simulations were conducted using the Environmental Fluid Dynamics Code (EFDC). Model simulations demonstrated regular variations in the lake surface elevation of 0.24–0.5 m associated with pumping and generation, although a large shore-mounted intake structure resulted in quite low velocities near the intake (< 6 cm/s), bottom shear values below the assumed critical threshold for resuspension (< 0.1 N/m2), and limited overall effect on stratification and mixing in the lake. Entrainment of larval fish and other planktonic organisms remains a concern, however.

Data Consolidation from Hydroelectric Plants

This paper presents a sequence of procedures for data analysis and correction from hydroelectric plants. The procedures are based on variable data recorded by the plant. Therefore, they do not require additional financial investment in instrumentation for measurements. The proposed methodology makes use of a data manager, a queries builder, a generator of the overall efficiency function and an electronic spreadsheet. It has been applied to the data from a large Brazilian hydroelectric plant whose operation is under the coordination of the Electric System National Operator (ONS). The benefits of the data correction are analyzed using a simulator of the hydroelectric plants operation. This simulator is used to reproduce the past operation of the plant, once with official data and the next with adjusted data. The results show significant improvements in terms of quality of the data, contributing to the efficiency and reliability of the computational models in use by the energy sector in the operation planning.

Condition of potentially unstable rock masses in the left-bank slope during construction and operation of the Sayano-Shushenskoe hydroelectric power plant

1. In connection with the fact that potentially unstable masses exist in the immediate vicinity of the dam and powerhouse, which are referred to as Class I structures in terms of capital expenditures, the approach taken for the design of PUM stabilization should be nonstandard with consideration given to a number of permanent vibratory design loads introiduced by operating hydraulic units and spillways, as well cyclically varying loads due to the weight of the water in the reservoir and the weight of the structures. 2. It is proposed to define the volumes required for PUM stabilization of the left-bank slope more precisely on the basis of observations of PUM during construction and operation of the hydroelectric plant. The interruptions that have occurred in the instrument observations should therefore be recognized as impermissible. 3. Construction and operating experience has demonstrated that it is expedient to perform work on stabilization of potentially unstable masses prior to the start of construction on entities located in their immediate vicinity. 4. A protective rock wall built at the foot of the slope cannot provide for the complete safety of the structures located close to the left-bank slope during the collapse of rock blocks or individual stones. 5. On-going monitoring of the condition of the left-bank slope does not correspond completely to problems of providing for the safety of the structures and personnel at the hydroelectric plant by reason of the low reliability of the measuring equipment. 6. Use of the automated “Relos-L” system for observations of the condition of the rock masses will make it possible to carry out continuous on-going monitoring within the framework of the automated production-control system at the Sayano-Shushenskoe hydroelectric plant. Only a multifunctional monitoring system, which includes different kinds of independent observations, can provide a sufficiently valid evaluation of the state of the PUM, and, on their basis, determine measures to prevent possible emergency situations. 7. The collapse of PUM in the initial stage of construction with subsequent plaining of the slope and the organization of multistory rock-entrapping benches is a more reliable, safe, and, probably, economical (if expenditures for future operation are assumed in the calculation) method than their stabilization.

Development and improvement of erection of mechanical equipment and metal components of hydraulic structures over the past 50 years

1. The development and improvement of the erection of mechanical equipment and metal components in the USSR over the past 50 years is inseparably linked with the solution of a large number of problems raised by wide hydraulic and hydropower construction. 2. For the erection work stages, the increase in the possibilities of Soviet machinery manufacture is characteristic, and, as a result, there has been a significant expansion of the stock of construction-erection mechanisms and transportation means. 3. For the development of mechanical equipment of high-head hydraulic structures, considerable volumes of analytical, experimental-research, and design work have been carried out. Data for design of the load-carrying elements of gates under dynamic loads have been obtained, and sealing elements, sliding and rolling supports for vertical-lift gates, and support hinges for radial gates have been developed. The coefficients of sliding friction of different types of seals have been experimentally determined, and problems of design, fabrication, and erection of high-head gates intended for operation under heads of up to 200 m have been solved. 4. A general characteristic of modern projects for the carrying out of erection of mechanical equipment and metal components is the striving for maximum reduction of the cost of hydraulic construction and of the times of completion, increase in the reliability and improvement of hydroelectric plant operation conditions, and use of new techniques and work automation. 5. During the past 50 years, the journalGidrotekhnicheskoe Stroitel'stvo has described and summed up the gathered erection experience, and has developed in the reader the capacity to apprehend, understand, and value hydraulic construction.

Improving the operation of hydroelectric plants and the journal's role in the dissemination of leading experience

Improving the operation of hydroelectric plants and the journal's role in the dissemination of leading experience

Operation of Hydroelectric Plants

Operation of Hydroelectric Plants

Seminars on Advanced Experience with Hydroelectric Plant Operation

Seminars on Advanced Experience with Hydroelectric Plant Operation