Pumped Storage Research Articles

Combined utilization of electricity and thermal storages in a highly renewable energy system within an island society

With the increasing share of intermittent renewable energy resources, the demand for different forms of energy storage increases. In this paper, a comparative analysis was performed on two energy storage solutions: small-scale underground pumped hydro storage (PHS) and high-temperature thermal energy storage (HTTES). Using the PLEXOS energy and power system modeling software, the study analyzed the operation and performance of these storage systems in Åland Island, an autonomous region of Finland. The novelty of the paper is in evaluating the business cases of these storage solutions when operating separately and combined. Business cases are studied by comparing annual energies, operating hours, price paid, and price received of the storage types in different scenarios. The results showed that both storages promoted electrification and renewable energy integration, with the HTTES reducing curtailment by 77 % and the PHS by 4 %. The storage systems were also able to take advantage of lower-cost hours of external electricity markets, with the PHS increasing electricity imports by 0.2 % and the HTTES by 1.5 %. Moreover, the PHS enabled the sale of excess electricity to external markets, leading to an increase in exports by 0.3 %. In contrast, the HTTES increased local consumption of excess production, reducing exports by 1.1 %. Results showed that integrating both storage systems in the same energy system could achieve significant benefits, such as reduced curtailment of renewable energy. However, the study also highlighted that the two systems could compete for the same resources in an open energy market, leading to a decrease in annual energy and net profits for both systems. A PHS exhibits an 11 % reduction in annual energies, when compared with operating alone, whereas for an HTTES, the reduction is 1 %. Similarly, the net profit of the PHS is reduced by 25.2 % and that of the HTTES by 4.9 %. Concluding the business case analysis, changes in annual energy and operation hours are not linearly correlated with revenue and charging cost, and the dynamics of the electricity market and the studied energy system must also be considered. Finally, energy storage can be considered a key element in supporting the energy transition; however, the importance of careful planning must be emphasized when integrating energy storage systems into an energy market.

Comparative techno-economic evaluation of energy storage technology: A multi-time scales scenario-based study in China

Energy storage technology is a crucial means of addressing the increasing demand for flexibility and renewable energy consumption capacity in power systems. This article evaluates the economic performance of China's energy storage technology in the present and near future by analyzing technical and economic data using the levelized cost method. Through a comparative analysis of different energy storage technologies in various time scale scenarios, we identify diverse economically viable options. Sensitivity analysis reveals the possible impact on economic performance under conditions of near-future technological progress. The application analysis reveals that battery energy storage is the most cost-effective choice for durations of <2 h, while thermal energy storage is competitive for durations of 2.3–8 h. Pumped hydro storage and compressed-air energy storage emerges as the superior options for durations exceeding 8 h. This article provides insights into suitable energy storage technologies for China's energy structure development in the present and near future.

Energy-Efficient Storage System Optimization and Recent Trends in Enhancing Energy Management and Access Microgrid: A Review

Energy is a vital component of our everyday lives, driving advancements in human development, economic expansion, and efficiency. Implementing sustainable energy storage systems is an economically viable approach to improving energy efficiency and regulating the generation and consumption of power. This study extensively examines energy storage, delving into several techniques, their practical uses, and the most recent progress. It focuses on environmentally sustainable alternatives for the electricity sector, including batteries, flywheels, thermal storage, and pumped hydro storage. The influence of includes compelling case examples, such as using vanadium redox flow batteries in maritime hybrid propulsion systems and advancing portable hydrogen energy storage devices. The results are encouraging, indicating that these technologies have the potential to be adequate replacements for traditional fuel sources, particularly in isolated areas where there is a critical requirement for energy storage. Moreover, this study thoroughly examines the integration options for energy storage in microgrids. It explores the complex aspects of the models, assessment indices, and optimization methods used in designing energy storage systems. This paper explores the capabilities of software used to determine the optimal size for energy storage systems. Furthermore, this study introduces and examines uncertainty analysis in modeling energy storage devices. This state-of-the-art technology has been created to demonstrate the effectiveness of energy storage systems in microgrids, providing crucial data for future progress in the industry.

Hydraulic-mechanical-electrical coupled model framework of variable-speed pumped storage system: Measurement verification and accuracy analysis

With the large-scale operation of wind and solar energy, the demand for energy storage in power grids has increased sharply. As a reliable means of long-term energy storage, the variable-speed pumped-storage power station (VSPSU) is a new development direction for pumped storage that has attracted increasing attention owing to its advantages of more rapid and flexible action. However, accurately predicting the transient process of a VSPSU is a key challenge in its design and operation. The inconsistent time step required for the fine simulation of the hydraulic-machine subsystem (millisecond level) and the electrical subsystem (microsecond level) is the main challenge that hinders the coordination of system simulation efficiency and accuracy and restricts further development of the entire coupling system simulation. Simultaneously, a coupling refinement model verified by multi-condition measurements has not been reported. This paper proposes a VSPSU hydraulic-mechanical-electrical coupling model framework that has been verified experimentally. The innovation of the model framework lies in the realization of the fine solution of the hydraulic and electrical systems through the coupling strategy of the variable simulation step size rather than using model simplification. Based on a real micro-VSPSU system, we conducted experiments under various operating conditions and compared the measurements with the numerical simulation results. The results showed that in the generation mode, the maximum simulation error of the proposed coupling model framework on the hydraulic-mechanical side was 2.29 %, and the maximum simulation error on the electrical side was 9.59 %. Finally, we quantified the contribution of key parameters in the model framework to the dynamic response process and clarified the influence of physical parameters on the transient process in the VSPSU. Compared with conventional models, the advantage of the proposed coupling framework is that it can realize the coupling of a hydraulic-mechanical-electrical system without simplification, which has been verified by measuring multiple working conditions. This framework provides a reliable tool for the parameter design and operation optimization of VSPSU.

Considerations for the static and seismic design of pumped storage reservoirs in soft soils and seismic environments

AbstractFor recent hydroelectric pumped storage projects, the construction of embankment dam structures on alluvial deposits consisting of exceptionally soft soil and in areas with high seismicity was required. This contribution shares experiences and challenges from the static and seismic design of embankment dam structures and ground treatment options. Finite element‐based static and seismic analyses using the Hardening Soil Small Strain model (HSS) showed that preconsolidation has clear benefits compared to stone columns for ground improvement purposes. Regardless of general advantages of surface sealing systems for frequent and rapid impoundment level changes, it was found that clay core design options perform very well under seismic loading conditions and even better than surface‐sealed structures. Seismic ground and structure response analyses involving soft soil considering shear strain‐dependent stiffness degradation revealed that deamplification is expected in contrast to the rule‐of‐thumb amplification approaches enshrined in many seismic design guidelines and codes. It was found that this effect increases with seismic magnitudes and that saturation of peak ground acceleration (PGA) takes place. This results in relatively moderate structure excitations even under significant dynamic excitation.

A highly efficient, low-carbon CCHP system and its comprehensive optimization for an integrated medical and nursing complex

As the global population ages, the demands imposed by medical treatment and care for the elderly are becoming increasingly pressing. To reduce energy consumption and systemic defects in the process of integrating medical treatment and care for the elderly, the authors of this study designed a highly efficient, flexible and low-carbon combined cooling, heating, and power (CCHP) system for the integration of medical and nursing complexes by using a multi-level model of optimization. The complex was modeled in DeST software to obtain the cooling and heating loads, and the general algebraic modeling system software and mixed-integer linear programming (MILP) were used for the collaborative optimization of the choice of equipment, capacity allocation, and operational strategy. The results showed that the proposed system could reduce the total consumption of electric power by 40.95 % when a semiconductor wall was installed on floors 8–12 of the complex for elderly care. The energy management strategy of the system was also optimized by using the vehicle-to-building subsystem in a novel wind–solar–storage and heat pump-based combined cooling, heating, and power system. The rates of reduction in emissions of CO2 and NOx, and the rate of reduction in primary energy consumption of the Wind–Solar–Storage and Heat Pump (WSSH)–CCHP system were 96.5 %, 99.1 %, and 95.6 %, respectively. Finally, the heat pump-assisted liquid-gap membrane distillation (HP-LGMD) subsystem were optimized in MATLAB. The resulting gained output ratio, flux, thermal efficiency of the system, and energy consumed for water production were 0.0269, 4.22 kg/m2, 17.07 %, and 46.88 %, respectively. The proposed system is highly energy efficient, is capable of economical scheduling, and can use energy cascading, which provides guidance on sustainable development of environment and energy.

Optimal Frequency determination for Wind-Hydro hybrid unit using Telegrapher’s Method for Low frequency transmission lines

This study addresses the optimal load flow problem for low-frequency transmission lines connected to wind farms and pumped storage Hydropower (PSH). The losses in LF-HVac system and the voltage stability index heavily dependent on the operating frequency. Therefore, an optimal load flow (OLF) method must be incorporated to determine the proper solutions for these systems. This system analyses the load flow solutions in which newton Raphson with STATCOM requires large vector calculations with variables. So, to reduce the mathematical calculation a two-port equivalent model for transmission lines based on solutions to Telegrapher’s method has been proposed. The proposed OLF method is tested with other algorithms and implemented in IEEE 39-BUS system. The results obtained indicate that the LF method with the proposed metaheuristic algorithm gives optimal frequency for low-frequency HVac systems while maintaining the stability of system.

Modelling and Simulation of 100 kW Pumped Storage Hydro Power System

Renewable energy sources are an attractive alternative option for augmenting the supply that comes from the utility Grid. This is because they are environmentally friendly. However Photovoltaic power generation is intermittent in nature. Hence, it is usually combined with energy storage systems such as batteries. In this study, pumped hydroelectric energy storage is used for supplementing the power produced from the Solar Photovoltaic system especially during peak demands and when the solar irradiance is low especially at night. Thus, the objective of this study is to model and simulate a pumped energy storage hydro system that can provide power supply of up to approximately 100 kW for a 10 hour period to service the night time. The proposed system is modeled using MATLAB Simulink. A total volume of 91836.7 m3 of storage water was calculated to achieve this purpose. Maximum torque of about 90 N/m was attainable when the angular speed of the water turbine was between 1100 and 1200 rpm. Recommendation for further works can be considered to maintain the angular speed of the turbine within this range.

Complementary assessment and design optimization of a hybrid renewable energy system integrated with open-loop pumped hydro energy storage

The intermittent nature of renewable energy resources is a major obstacle in utilizing such resources for power generation despite their abundance. In this paper, a dynamic analysis of an integrated system based on photovoltaic (PV) panels and wind turbines coupled with pumped hydro energy storage is presented. When the power generation exceeds the power demand, surplus electricity is used to pump the water to the upper reservoir. The natural inflow of the river obviates the necessity for oversized reservoirs and saves costs. A recently introduced multi-objective equilibrium optimizer algorithm is developed to find the optimal size of the integrated hybrid energy system. The objectives are to minimize the levelized cost of electricity and maximize the reliability of the proposed system. The results show that the correlation between solar and wind power generation in the selected location is mildly strong with a value of 0.3. The total energy generation from hydro, solar, and wind resources are 77,508.7 kWh, 103,323 kWh, and 47,375.4 kWh, respectively. Comparing the results with other algorithms indicates that the equilibrium optimizer has a better performance in finding the optimal design.

Uncertainty Estimation in the Modeling of a Flood Wave Caused by a Dam Failure in a Hydropower System with Pumped Hydro Energy Storage

Future global sustainability depends heavily on the development of renewable energy. The object of this study is a system of two plants (Kaunas hydropower plant (HP) and Kruonis pumped-storage hydropower plant) and upper and lower reservoirs. A possible dam failure accident in such an important system can endanger the population of Kaunas City. The methodology for estimating dam-failure-induced flood wave uncertainty included scenarios of the upper reservoir embankment failure hydrographs, modeling flood wave spreading (MIKE 21 hydrodynamic model), and estimating wave heights. The GRS methodology was selected to assess the uncertainty of flood wave modeling results and the sensitivity of hydrodynamic model parameters. The findings revealed that the discharge values of the Nemunas inflow and outflow through the HP outlets are the most important parameters determining the greatest height of the flood wave. Therefore, by correctly managing the amount of water in the upper reservoir, it would be possible to prevent the lower reservoir dam from breaking.

Prediction formula of blasting vibration under complex terrain based on dimensional analysis

The accurate prediction of blasting vibration plays an important role in the evaluation of blasting negative effects and the optimization of blasting design. On the premise of clarifying the influencing factors of blasting vibration propagation, combined with dimensional analysis, based on the traditional Sadovsky formula, through the introduction of horizontal distance and elevation difference factor, the attenuation law of blasting vibration under mountainous terrain conditions is studied, and the blasting vibration prediction formula reflecting mountainous terrain conditions is established. Combined with the measured vibration data of underground powerhouse excavation of Xiamen pumped storage power station in Fujian Province, when the elevation between the measuring point and the explosion source changes greatly, the prediction errors of horizontal and vertical vibration by using the traditional Sadovsky formula are large, about16 ~ 25%respectively. The prediction errors of vibration prediction formula based on dimensional analysis are small, about 8 ~ 12%. The results show that the particle vibration peak formula based on dimensional analysis can be better applied to the prediction of blasting vibration under complex terrain.

Multi-Objective Dynamic Economic and Emission Generation Scheduling of Coordinated Power System Considering Renewable Energy Sources and Pumped Storage Hydro Plants via Fuzzy Surrogate-Assisted Coronavirus Herd Immunity Optimization

Globally, the power generation from renewable energy sources (RES) has received considerable attention to reduce pollutant emissions and the total operating costs of power generation. In this context, this study aims to extend the multi-objective dynamic economic and emission dispatch (MODEED) problem by incorporating RES and pumped storage hydro plants. The complex constrained MODEED problem is solved by a fuzzy surrogate-assisted coronavirus herd immunity optimization (FSACHIO) algorithm in which a self-adaptive speed factor and Lévy flight mechanism are utilized to ensure populace diversity, prevent premature convergence and achieve an ideal stability among the exploration and exploitation of the algorithm. Surrogate worth tradeoff methodology is used to discover a solution that provides the optimal balance between the objectives such as operating expenses and emission pollutants. The performance of FSACHIO algorithm is validated on a small-scale and a large-scale test systems, involving 10-unit, and 40-unit test systems, and compared with that of the coronavirus herd immunity optimization, red fox optimizer, Remora optimization algorithm, and other erstwhile approaches. Besides, a fuzzy constraint handling method based on a dominance relationship is integrated to fulfill the restrictions of the MODEED problem. The simulation results reveal that: (i) the operating costs and emissions are reduced by 173785.54 $/day and 2992.1848 lb/day in the small-scale test system and by 6383.9903 $/day and 216631.4877 lb/day in the large-scale test system, respectively for the MODEED problem with the presence of RES and pumped storage hydro plants; (ii) the suggested approach may offer a well-distributed Pareto-optimal frontier and superior tradeoffs among the operating expenses and pollution objectives in comparison to the other approaches.

Research on the slip deformation characteristics and improvement measures of concrete-faced rockfill dams on dam foundations with large dip angles

The pumped storage power station (PSPS) is an important measure to achieve the strategic goal of “dual carbon”. As one of the preferred types for the upper reservoir dams of PSPSs, the concrete-faced rockfill dam (CFRD) often has a dam foundation on a steep transverse slop and is prone to produce slip deformation along the slope, resulting in poor anti-sliding stability of the dam slope. It is dangerous for the operation safety of PSPSs. Therefore, the slip deformation of CFRDs on dam foundations with large dip angles is investigated. The mechanism for the initiation of slip deformation is revealed. The design measures of physical mechanic and geometric structure are proposed to reduce slip deformation. The results show that the larger sliding forces and smaller anti-sliding forces are the fundamental reasons that CFRDs on dam foundations with large dip angles are prone to produce slip deformation. The larger the dip angle of the dam foundation, the larger the slip deformation of the dam body and face slab, and the smaller the safety factor of the dam slope. When the dip angle of the dam foundation is greater than 15°, the safety factor of the dam slope is less than the minimum value of 1.5 required by codes. The addition of pressure slopes can effectively reduce the slip deformation of the dam body or face slab and significantly improve the anti-sliding stability of the dam slope. When the height or width of the pressure slope platform is greater and the cohesion or internal friction angle of the pressure slope is larger, the slip deformations of the dam body and face slab are smaller, and the safety factor of the dam slope is greater. It is recommended that the height and width of the pressure slope platform be 1/2 times the maximum height of the main dam, and the density (cohesion and internal friction angle) of the pressure slope be equivalent to that of the main dam’s rockfill material. The research results can provide theoretical and technical support for the design and construction of CFRDs for the upper reservoir of PSPSs.

Loss of load probability for power systems based on renewable sources

An increasing number of small and variable power sources, such as wind and solar power plants, are being integrated into power systems, potentially affecting their reliability. This study was aimed at developing a method for evaluating reliability in terms of the loss of load probability. To this end, an algorithm capable of assessing the expanded role of renewable sources in the power system was established, which could take into account the specific roles and features of wind, solar, and hydro power plants, including pumped storage hydro power plants. Various models were developed and tested to closely emulate real power system behavior. A regional power system was evaluated over multiple years. The results indicated that the reliability of power systems fluctuates with the available capacity of renewable resources. These findings provide a foundation for a more precise specification of power reserves in such systems to prevent excessive reduction in reliability.

Virtual Power Plant and Microgrid Control Integration for Campus Environments with Wind Solar Pumped Hydro and Biomass Energy

This paper provides a comprehensive exploration of integrating renewable energy sources, focusing on wind, solar, Pumped Hydro and biogas, into power systems. Virtual Power Plants (VPPs) with an Energy Management System (EMS) offer a promising solution for managing these distributed resources. The VPP model, utilizing mixed integer linear programming (MILP) in GAMS and solved with CPLEX, optimizes net daily profit within a 24-hour interval. This approach efficiently allocates resources, maximizes profitability, and ensures stable energy supply, addressing the challenges posed by variable renewable energy outputs. The MILP model is formulated using linear equations and inequalities within GAMS, with the CPLEX solver being effective for handling large-scale linear programming tasks. The model is based on real-world data, including market variability, weather forecasts, and demand patterns, and can be optimized for better decision-making in VPP operations, ultimately maximizing profits while ensuring a stable and sustainable power supply.

Optimal sizing and location of grid-interfaced PV, PHES, and ultra capacitor systems to replace LFO and HFO based power generations

The impacts of climate change, combined with the depletion of fossil fuel reserves, are forcing human civilizations to reconsider the design of electricity generation systems to gradually and extensively incorporate renewable energies. This study aims to investigate the technical and economic aspects of replacing all heavy fuel oil (HFO) and light fuel oil (LFO) thermal power plants connected to the electricity grid in southern Cameroon. The proposed renewable energy system consists of a solar photovoltaic (PV) field, a pumped hydroelectric energy storage (PHES) system, and an ultra-capacitor energy storage system. The economic and technical performance of the new renewable energy system was assessed using metrics such as total annualized project cost (TAC), loss of load probability (LOLP), and loss of power supply probability (LPSP). The Multi-Objective Bonobo Optimizer (MOBO) was used to both size the components of the new renewable energy system and choose the best location for the solar PV array. The results achieved using MOBO were superior to those obtained from other known optimization techniques. Using metaheuristics for renewable energy system sizing necessitated the creation of mathematical models of renewable energy system components and techno-economic decision criteria under MATLAB software. Based on the results for the deficit rate (LPSP) of zero, the installation of the photovoltaic field in Bafoussam had the lowest TAC of around 52.78 × 106€ when compared to the results for Yaoundé, Bamenda, Douala, and Limbe. Finally, the project profitability analysis determined that the project is financially viable when the energy produced by the renewable energy systems is sold at an average price of 0.12 €/kWh.

Optimal operation of pumped storage power plants with fixed- and variable-speed generators in multiple electricity markets considering overload operation

This work studies the optimal operation of pumped storage power plants with fixed- and variable-speed generators in different electricity markets. This paper extends the state of the art by systematically considering the detailed plant behavior for heterogeneous pumped storage power plants and the possible short-term electrical overload operation. The Day-Ahead, ancillary service, and Intraday markets are studied in the first part by developing a mixed integer nonlinear problem (MINLP). The results demonstrate that variable-speed units, especially if equipped with doubly-fed induction machines (DFIMs), yield the highest profit, particularly in the presence of automatic Frequency Restoration Reserve (aFRR). The proposed optimization of the Intraday market shows that the total profit of the Day-Ahead, Ancillary services, and Intraday markets are the highest in the case of variable-speed units with aFRR, where it might be a drawback offering Frequency Containment Reserve. Finally, a robust optimization-based bidding curve generation strategy is developed in the last step. The strategy allows the plant to operate with high profits under price prediction uncertainties and enables optimal reservoir management. The developed optimization tasks and the bidding curve generation strategy also exhibit shorter computation times than the state-of-the-art strategies.

Interpretable GBDT model-based multi-objective optimization analysis for the lateral inlet/outlet design in pumped-storage power stations

ABSTRACT The uneven velocity distribution formed at the lateral inlet/outlet poses a significant risk of damaging the trash racks. Reasonable design of the inlet/outlet structures requires the consideration of two major aspects: the average velocity (Vm) and the coefficient of unevenness (Uc). This paper developed an optimization framework that combines an interpretable Gradient Boosting Decision Tree (SOBOL-GBDT) with a Non-dominated Sorting Genetic Algorithm (NSGA-II). 125 conditions are simulated by performing CFD simulations to generate the dataset, followed by GBDT implemented to establish a nonlinear mapping between the input parameters including vertical (α) and horizontal (β) diffusion angles, diffusion segment length (LD), channel area (CA), and the objectives Uc and Vm. The SOBOL analysis reveals that in Uc prediction, CA and α play more significant roles in the model development compared to β and LD. Besides, GBDT is observed to better capture interactive effects of the input parameters compared with other machine learning models. Subsequently, a multi-objective optimization framework using GBDT-NSGA-II is developed. The framework calculates the optimal Pareto front and determines the best solution using a pseudo-weight method. The results demonstrate that this framework leads to significant improvements in flow separation reduction in the diffusion segment and the normalized velocity distribution. The SOBOL-GBDT-NSGA-II framework facilitates a rational and effective design of the inlet/outlet.

Pumped Storage Hydropower as a Part of Energy Storage Systems in Poland—Młoty Case Study

The increase in the share of renewable energy sources (RES) leads to a growing need for sources or systems/actions to stabilize the national energy grid. Such stabilizing actions include market tools, such as prices and demand-side response (DSR) tools, as well as flexible energy sources (e.g., gas). In addition, energy storage, where pumped storage hydroelectricity (PSH) accounts for 90% of global storage capacity, plays an important role. Therefore, the authors presented a detailed analysis of PSH in the context of the dynamic growth of installed capacity in renewable energy sources. They analyzed the economic viability of this type of power plant, with a particular emphasis on operational costs, energy production, and revenue. The Młoty case study and market data, including historical data on various PSH, were presented and analyzed. This study uses copulas, simulation, and statistical analysis. The authors proved that market prices and arbitrage actions alone are not sufficient to achieve profitability of the investment; however, additional benefits, such as fees for available power, enable the achievement of economic profitability. The reason for this is the fact that one of the main goals of PSH is to serve as a power reserve. In addition, this paper presents the analysis of the utilization of existing PSH in the form of full pumping and energy generation cycles (charging and discharging storage).

Application of the Tracer Test in a Hydrogeological Survey for a Pumped Storage Power Station

In areas with complex hydrogeological conditions, the tracer test method is often used as an effective means in hydrogeological surveys. According to the results of tracer tests, hydrogeological parameters, including hydraulic gradient and permeability coefficient, fracture network leakage passages and their scale, and groundwater flow rate and direction can be quantitatively determined. This paper takes the upper reservoir of Yongxin Pumped Storage Power Station in Jiangxi Province as the research object, and focuses on the complex hydrogeological conditions of the upper reservoir. Three sets of tracer tests and multiple sets of single-hole flow rate and direction tests were conducted on the left and right banks of the reservoir and near surface gullies. The results showed that ZKS18 received tracers in all three tests, which indicates a close hydraulic connection between ZKS18 and the left bank, right bank, and surface gullies within the reservoir. Based on the single or multiple peak values of the tracer, it was determined that there are 1–6 leakage passages in the fractured rocks, with leakage passage sizes of 0.1–0.4 mm. According to the single-hole flow rate and flow direction tests, a self-developed instrument was used to determine the groundwater flow rate and flow direction at different depths in the test holes, which yielded results that were basically consistent with the results of the three-hole method. These results provide a basis for the use of tracer tests in hydrogeological surveys for water conservancy and hydropower engineering, and anti-seepage design of upper reservoirs.