Storage Power Plant Research Articles

Load flexible control method for wind and solar energy storage power plant considering the power side demand

Load flexible control method for wind and solar energy storage power plant considering the power side demand

Research on Design Parameters of Pumped Storage Power Station Based on Different Geographical Locations

Energy storage technology plays an extremely crucial role in the transition of the current social energy structure to renewable energy. Energy storage technology with high efficiency, safety and long storage period has become the key to breaking through the limitations of renewable energy utilization. As one of the most widely used large-scale energy storage technologies, pumped storage hydropower (PSH) has the advantages of high efficiency and large energy storage capacity. It has good development potential in countries with abundant water resources, but there are also problems such as high initial investment, high cost, construction. The cycle is long and largely limited by geographical conditions. This paper analyzes the parameters of PSH station in different geographical locations, compares their differences based on the cost per unit of electricity of the whole life cycle, explores the relationship between the location of pumped storage power plants and the cost of power per unit of electricity, and provides a basis for promoting the development of this technology. Provide effective technical support for development.

Calculation method of external fault short-circuit current for variable-speed pumped storage units based on time-domain dynamic circuit

The calculation method of the external fault short-circuit current of large units with clear mechanisms and practicality is of great value in engineering practice. Due to the special AC excitation structure and control mode, the external fault short-circuit characteristics of variable-speed pumped storage units (VSPSUs) are very different from those of conventional units. Therefore, this paper proposes a calculation method for external fault short-circuit current based on a time-domain dynamic circuit. According to the excitation and control characteristics of VSPSUs under external fault, the VSPSU under external fault is divided into two cases: continuous excitation and jumper action. Based on space vector analysis, the time-domain dynamic circuit models are established, respectively. On this basis, the analytical formula of the external fault short-circuit current of VSPSUs is derived by combining the transition boundary conditions of the two cases and the dynamic characteristics of the stator flux linkage. Finally, the comparison with PSCAD/EMTDC simulation results shows that the proposed VSPSUs’ external fault short-circuit current calculation method has high accuracy and practical value, which can meet the needs of primary equipment selection and relay protection of variable-speed pumped storage power plants.

Prefeasibility analysis of the Pumped Hydro Storage (PHS) system in Türkiye: A case study on a hybrid system

Pumped Hydro Storage (PHS) power plants aim to exploit the price difference between storing and generating electricity. These power plants operate by pumping water from the lower reservoir to the upper reservoir, consuming energy, and generating electricity by transferring water from the upper reservoir to the lower reservoir. There is no pumped storage power plant in Turkey yet, and it is in the planning stage. This study aims to provide a preliminary feasibility analysis of this investment from an economic and technical point of view and to contribute to this issue through the recently announced feed-in tariff for PHS. The planned PHS at Gökçekaya Dam was considered a proposal in this study and was carried out using a developed algorithm. The algorithm determines the optimal installed capacity of hybrid energy. This feasibility analysis is based on two scenarios. The difference between the first and second scenarios is due to the investment cost of the PHS system. Additionally, the second scenario considers an integrated hybrid Solar Hydroelectric (SHE) system. Each scenario is evaluated in terms of base price, average price, maximum feed-in price, and market peak price. The result of the study is that only the market price represents a remarkable payback period for pumped storage power plants. As a result of the study, it was found that it’s possible to support the pumped storage power plant with a hybrid solar power system and market price if only the storage volume is increased. The feed-in tariff should be set to cover the demand. In the first scenario, only the PHS was evaluated, and after completing the economic analysis, the investment has a payback period of 28.39 years for the market peak price. If the PHS facility is supported by a hybrid solar energy system for internal energy needs, the payback periods can be reduced. In the first scenario, the investment has a payback period of 18.05 years, supported by integrated hybrid solar energy. In the second scenario, the PHS investment has a payback period of 9.63 years for the highest price on the market. The investment has a payback period of 8.66 years, which is supported by the integrated hybrid solar energy. Due to the high self-consumption of energy, integrated hybrid solar energy is suitable for the PHS projects.

Thermodynamic and economic analyses of the integrated cryogenic energy storage and gas power plant system

Thermodynamic and economic analyses of the integrated cryogenic energy storage and gas power plant system

Retrofit of a coal-fired power plant with a rock bed thermal energy storage

Power production accounts for about one-fifth of the global final energy consumption and over one-third of all energy-related CO2 emissions. Low-cost, large-scale thermal energy storages are considered as solutions for the decarbonization of fossil-fired power plants by their conversion into power-to-heat-to-power systems, so-called thermal storage power plants. This paper investigates the retrofit of a Chilean coal-fired power plant with an innovative solid media storage from a techno-economic perspective. Selecting a storage capacity of 5.27 GWhth, corresponding to 8 h of discharge, and increasing the inlet steam generator temperature from 590 to 650 °C lead to the highest annual round-trip efficiency of 34.9% and to up to 3.4% lower levelized cost of electricity. Minimum levelized cost of electricity as low as 88.1 €/MWh is attained and considered as close to competitiveness with well-established molten salt storage systems. A sensitivity analysis shows that assuming even five times lower storage costs, initially the strongest driver of capital expenditure, only meant 4% lower levelized costs of electricity on average. On the other hand, the design of electricity purchase for charging, for example with green power purchase agreements, turns out to be the key lever to a successful implementation.

Conflict and uneven development in the multidecade distributed solar energy transition in the United States.

A longitudinal analysis of small-scale solar energy generation in the United States is used to demonstrate how transition studies can explain nonlinearity in multidecade changes of consumption-production systems. Nonlinearity involves uneven development of sustainability innovations with episodes of rapid growth but also periods of slow growth, stalling, or even collapse. Factors that affect the increasing feasibility and attractiveness of small-scale solar include technological improvements, declining costs, and changes in global energy markets. However, a more complete explanation of nonlinearity highlights the importance of a type of systems analysis that also includes strategic action and broader societal and policy changes. Specifically, efforts by the utilities constrained the growth of small-scale solar by weakening policy support because of the perceived threat, but the solar industry and advocates responded with countervailing action in a changing context. As the transition developed, strategic action (including goals, targets, tactics, and coalition partners) changed and became more conflictual. However, by the beginning of the 2020 decade, the development of microgrids, digital technologies, storage, and virtual power plants in combination with net-zero energy policies provided indications of potential for a reconfiguration of the relationship that could be less polarized and conflicted.

Challenges of Large Converter-Fed Synchronous Machines for Variable-Speed Pumped Hydro Storage

The green energy transition of electrical energy production is leading to an increasing share of total energy production for volatile renewable energy sources, mainly wind and solar power. To handle this volatile production, flexible and efficient energy storage is required. The development of high-power converters has enabled the generation of variable-speed pumped hydro storage power plants, combining the so-far-unequalled energy storage capacity of classical pumped-storage hydro power plants and the recently increased operation requirements. The introduction of large-scale converters has led to new challenges in the overall design of power plant systems. This paper intended to take a closer look at a large-scale converter-fed synchronous generator, especially the distribution of the current and voltage harmonics caused by the converter in the implemented generation system. Thereby, holistic design considerations for an ideal loss distribution as well as possible measures to limit the effects of harmonic coupling at the generator shaft and bearings are discussed. Furthermore, basic considerations of harmonic emission to the connected network are described. These topics are addressed by analyzing on-site measurements at an 85 MVA converter-fed synchronous generator with a voltage source inverter, underpinned with the theoretical background.

Hydraulic disturbance characteristics and power control of pumped storage power plant with fixed and variable speed units under generating mode

Hydraulic disturbance characteristics and power control of pumped storage power plant with fixed and variable speed units under generating mode

Thermal storage power plants – Key for transition to 100 % renewable energy

Transition from fossil/nuclear towards renewable energy supply can be achieved in three phases: firstly, variable renewable electricity (VRE) can be fed into the electricity grid just as available, while its fluctuations are balanced by thermal power plants fired by fossil fuels. Secondly, after achieving grid saturation with VRE, the residual load gaps must be covered and grid stability must be secured by highly flexible thermal power stations that generate dispatchable renewable electricity (DRE) without using fossil fuels. Thermal Storage Power Plants (TSPP) that integrate solar- and bioenergy are proposed for that purpose. Finally, in the third phase, renewable power supply can be extended to other sectors via power-to-X technologies, reducing fossil fuel consumption for transport, heat and industrial purposes. The phases of energy transition are described in the frame of a model scenario of the German electricity sector with TSPP as central element for the realization of Phase 2.

Feasibility Analysis of Compressed Air Energy Storage in Salt Caverns in the Yunying Area

With the widespread recognition of underground salt cavern compressed air storage at home and abroad, how to choose and evaluate salt cavern resources has become a key issue in the construction of gas storage. This paper discussed the condition of building power plants, the collection of regional data and salt plant data, and the analysis of stability and tightness. Comprehensive analysis and evaluation methods were put forward from four aspects, including ground comprehensive conditions, regional geological conditions and formation lithology, salt mine characteristics, stability, and tightness of salt caverns. The limit equilibrium theory was applied to establish the limit equilibrium failure mode of salt caverns under operating pressure, and the stability coefficient calculation method of the target salt cavern was determined by combining the mechanical characteristics. Based on the physical and mechanical properties of salt rocks, it was found that salt rocks with enough thickness around the salt cavity could be used as sealing rings to ensure the tightness of the salt cavern. Combined with the field water sealing test, the tightness of the target salt cavern is verified. This method has been applied to the salt cavern screening and evaluation of a 300 MW compressed air energy storage power plant project in Yingcheng, Hubei Province, and remarkable results have been obtained, indicating the rationality of the method.

Simulation analysis of energy characteristics of flow field in the transition process of pump condition outage of pump-turbine

The pump-turbine is the heart of a pumped storage power plant. This study combines numerical simulations with experiments to investigate the flow stability, energy loss in the main flow area and their interconnection in the transition process of the double-row cascade and runner chamber of the pump-turbine, when the pump-turbine is operated under pumping conditions with a sudden power failure and the guide vane refuses to close. The results show that the overall flow pattern of the transition process is extremely unstable, and the flow state is presented as smooth-disturbed-smooth-disturbed, with the maximum vorticity difference(Δω) of 696756 s−1 in the neighboring working conditions; the maximum entropy production rate of the double-row cascade and runner chamber in the braking process has a similar trend in the vorticity change trend, and the rapid change of the flow pattern of the internal fluid causes the sharp change of the entropy production in the pump-turbine; The maximum entropy production rate in the runner chamber is of the order of e6, which is much higher than that in the other regions, and the poor flow phenomenon caused by the runner is the main reason for the energy loss.

Analysis of multimodal performance of a hybrid solar pumped storage system for enhanced energy security in rural areas

ABSTRACT Remote hilly hamlets in India still face acute energy security problems. As a solution, the present study discusses a Novel Hybrid Solar Pumped Storage Powerplant that can operate in grid-connected and standalone modes to provide stable power throughout the year. Genetic algorithm-based optimization techniques and actual resource and demand data were utilized to optimize the system’s design. Site-specific power generation and grid interaction models were established and multiple operational modes of the system were simulated with a system dynamics modeling approach. Results show a 73% reduction in greenhouse emissions, a levelized energy cost of 0.09$/kWh, and assured generation security of 82% during standalone operation. The probability of power supply loss during the grid-connected operation was minimized, and 20% was incurred during standalone operation. This innovative solution can provide reliable and sustainable power to remote hilly hamlets, contributing to the Sustainable Development Goal (SDG)-7 and helping India achieve its COP-26 & 27 commitments. As the government takes active initiatives to improve grid stability in remote locations, this system can be effectively implemented and scaled up to provide a cost-effective and environmentally friendly solution for storage and utilization of solar power.

Thermodynamic analysis and optimization of liquid air power plant integrated with parabolic trough solar collectors

ABSTRACT As to investigate the impact of parabolic trough collector optical characteristics on the comprehensive performance of solar-driven liquid-gas energy storage power plants, this study establishes a mathematical analysis model for a liquid-gas energy storage power plant with a parabolic trough collector. The effects of direct irradiance, collector tracking mode, and component configuration on collector efficiency, round-trip efficiency, and exergy efficiency are analyzed. The results show that when the direct irradiance exceeds 400 W/m2, the round-trip efficiency of the system decreases while the exergy efficiency increases. For every 100 W/m2 increase in irradiance, the round-trip efficiency decreases by 1.54%, and the exergy efficiency increases by 2.36%. The north-south axis tracking mode is superior to the east-west axis tracking mode and dual-axis tracking mode. The component configuration improves the collector efficiency and round-trip efficiency but decreases the thermal efficiency. In low irradiance conditions (direct irradiance less than or equal to 400 W/m2), the system performance is optimal when the collector optical efficiency is maintained at 74%. Under these conditions, the system achieves a maximum net energy output of 495.12 kW·s/kg, the exergy efficiency of 54.5%, and the round-trip efficiency of 18.96%. In high irradiance conditions (direct irradiance greater than 400 W/m2), a 10% increase in collector optical efficiency leads to a 1.94 kW·s/kg decrease in net energy output, a 3.14% decrease in exergy efficiency, and a 0.05% decrease in round-trip efficiency.

DEM-based study of hydraulic fracturing mechanism under high internal water pressure

To solve the problem of fracturing due to high water pressure when pumping in the diversion tunnel, the mechanism of hydraulic fracturing (HF) in the tunnel under high internal water pressure is studied. A numerical model of HF considering water-rock interaction is established using the PFC2D discrete element simulation software. The HF mechanism of surrounding rock under high internal water pressure is studied, and the development process of hydraulic cracks is obtained. The influence of surrounding rock parameters on fracturing is analyzed and the law between principal stress and crack development is investigated. The high-pressure water injection test under different tunnel diameters is also carried out. Numerical test research shows that under the action of high internal water pressure, the surrounding rock at the cavity wall splits first, and the water entering the crack generates water pressure on the crack sidewall, which in turn generates tensile stress at the crack tip and further causes the crack expansion. The crack length is exponentially related to the internal water pressure. The high internal water pressure decays gradually with the crack extension distance and stabilizes when the crack extension reaches a certain length because the water pressure is less than the tensile strength of the surrounding rock. The fracturing results indicate that the process of HF damage is tensile types, and the increase of cohesion plays a suppressive role in crack opening, while the internal friction angle has little effect on the HF effect. The influence of principal stress on the HF result shows that the direction of HF is along the direction of major principal stress. The major principal stress promotes the cracking, while the minor principal stress inhibits the crack growth. By simulating the water injection test for different hole diameters of the diversion tunnel, it is found that the fracturing distance of the surrounding rock increases approximately linearly with the increase of the hole diameter. The test results can provide a basis for the design and construction of high-pressure tunnels such as pumped storage power plants.

A novel capacitor voltage fluctuation suppression method for the low-frequency operating stage of MMC driven pumped storage system

The pumped storage power plant, which has the energy conversion and storage capacity, is an important solution for improving the power grid absorption ability to the unstable and fluctuating new energy from wind farms, as well as photovoltaic power stations. The modular multilevel converter (MMC) is a competitive topology for driving the pumped storage motor due to the advantages of high output power level and low output current harmonics. However, the voltages of the sub-module capacitors fluctuate largely when the MMC is operating at low-frequency stage, which would lead to an abnormal start-up process or an unstable low-speed running state of the variable speed pumped storage system. In order to suppress the low-frequency voltage fluctuation of the MMC sub-module capacitors, this paper proposes a charge channel topology including in-phase and inter-phase channel between the sub-modules for transferring the capacitor charge. Then, the reverse fluctuating fundamental component and third harmonic circulating component, as well as the synchronizing fluctuating second harmonic component, of the sub-module capacitor voltages could be counteracted, respectively. Eventually, the start-up operation performance, as well as the low-speed operation performance of the variable speed pumped storage system are enhanced greatly. The effectiveness of the proposed low-frequency capacitor voltage fluctuation suppression method is verified through simulation results.

A novel topology of drive & thermal model for variable speed pump-storage power plant

Improving drive techniques in variable-speed pumped storage power plants (VSPSPs) for optimal performance, higher efficiency and lower loss is an ongoing challenge in light of these plants' considerable high power output and consumption. Introducing a new direct torque & flux controller (DTFC)-based driver with 3 level voltage source convertor-active neutral point clamped (3LVSC-ANPC) for this power plant, this paper proposes a novel communication and operation topology for the voltage converter with a 5 + 1 layout, in which a driver central control unit (DCCU) controls each converter as an independent power module. This layout consists of five parallel and one redundant power module. Hydraulic and electric VSPSP models are presented to allow for a better grasp of the topic. In the following, models and thermal equivalent circuits of the drivers are presented before investigating the results of MATLAB and PLEXIM simulations in the end. The project is also verified and validated by statistical analysis, proving improved efficiency, reduced THD and lower driver losses by employing the new driver in the power plant.

A study on site selection of pumped storage power plants based on C-OWA-AHP and VIKOR-GRA: A case study in China

Pumped storage power plants (PSPP), as an important clean energy technology, have great potential for energy storage and conditioning. However, site selection is the primary issue in PSPP construction, which directly affects its economics, environmental impact and social acceptability. Therefore, this paper aims to conduct an in-depth study of PSPP site selection, taking into account multiple factors such as geology, hydrology, environment and socio-economics, to determine the best site in a scientific and objective manner. In our study, we used the literature review method and Delphi method to determine the index system for PSPP site selection evaluation, calculated the objective and subjective weights of the indexes by C-OWA and AHP, respectively, and used Lagrangian optimization to calculate the combined weights. In addition, the VIKOR-GRA method was used to evaluate and rank the candidate site selection options to determine the best site location, and the robustness of the research results was tested by sensitivity analysis and comparative analysis. The results of the study indicate that within Anhui Province, the Yuexi area of Anqing is considered to be the most promising and advantageous PSPP site location. This study provides scientific and feasible guidance for PSPP site selection, which is important for promoting clean energy development and achieving sustainable energy supply.

Energy Storage Potential Needed at the National Grid Scale (Poland) in Order to Stabilize Daily Electricity Production from Fossil Fuels and Nuclear Power

With the increasing share of renewable sources in the energy mix, there is a need to balance energy production from weather-dependent sources, such as wind turbines and photovoltaics. This is also a current global trend associated with climate policy. In Poland, there has been a significant increase in energy production from renewable sources, leading to a duck curve phenomenon mainly in the case of photovoltaics, which requires balancing this production through various measures. One possible way to achieve this is energy storage installation. This article identifies the need for energy storage to ensure the stability of electricity production from low-flexibility sources like coal-based power plants. For this purpose, a methodology has been developed to determine the daily minimum energy storage capacities which would also allow for the integration of other stable (though less flexible) energy sources, such as nuclear power. In the case of Poland, energy storage has been estimated to require, as a median value, approximately 6 GWh of additional storage capacity, which is equivalent to twice the planned capacity of the Młoty Pumped Storage Power Plant.

German atlas of Thermal Storage Power Plants (TSPP) - A first approach

The paper assesses the potential of transforming conventional power plants to Thermal Storage Power Plants (TSPP) in Germany on a macro scale. The resulting atlas is based on a scenario of the power sector published before that assumes that current conventional power plants will be transformed to TSPP with a capacity of 70 GW in 2040, providing reliable power supply for the residual load. In order to achieve this, several criteria are introduced that rank all power plants in Germany in terms of suitability for such conversion. Moreover, a method of finding the necessary land areas for PV and biomass required as primary energy sources for the TSPP is described with the help of a geographic information system. The analysis is divided into 2 parts: The first part is to consider the whole country as a single entity, and all power plants are analyzed according to their ranking list in order to find out if the scenario is consistent with existing PV and biomass potentials. The second part focuses on individual power plants without considering the ranking list, in order to find the best potential PV and biomass supply areas for each potential power plant that could be transformed on a first-come-first-save basis. The findings of this study include mapping of the transformation potential of individual power plants, and also provides an integrated framework for a TSPP transition at the national level. By providing a comprehensive overview of the TSPP-atlas across the country, these maps may serve as a helpful tool for policymakers and power plant owners in making decisions regarding the deployment of TSPP.