Hydro Storage System Research Articles

Value of pumped hydro storage in a hybrid energy generation and allocation system

Transition from fossil fuels to renewable sources is inevitable. In this direction, variation and intermittency of renewables can be integrated into the grid by means of hybrid systems that operate asa combination of alternative resources, energy storage and long distance transmission lines. In this study, we propose a two-stage stochastic mixed-integer programming model for sizing an integrated hybrid energy system, in which intermittent solar generation in demand points is supported by pumped hydro storage (PHES) systems and diesel is used asan expensive back-up source. PHES systems work asa combination of pumped storage and conventional hydropower stations since there is also natural streamflow coming to the upper reservoirs that shows significant seasonal and inter-annual variability and uncertainty. With several case studies from India, we examine the role of high hydropower potential in the Himalaya Mountains to support solar energy generation in the form of pumped hydro or conventional hydro system while meeting the demand at various scales. We show that pumped hydro storage can keep the diesel contribution to meet the demand less than 10%, whereas this number can go up to more than 50% for conventional systems where the streamflow potential is limited compared to the demand. We also examine the role of pumped hydro systems in both isolated and connected systems (through inter-regional transmission lines) and show that the benefit of pumped hydro is more significant in isolated systems and resource-sharing in connected systems can substitute for energy storage. In addition, with the help of the proposed model, we show that the upper reservoir size of a pumped hydro system could be lower than the reservoir size of a conventional hydropower system depending on the demand scale and streamflow availability. This means that, most of the current conventional hydropower stations could be converted to pumped hydropower stations without needing to modify the upper reservoir, leading to a significantly reduced diesel contribution and lower system unit cost.

Optimal energy management of a grid-connected micro-hydrokinetic with pumped hydro storage system

Renewable energy sources are the key alternatives to mitigate the issue of greenhouse gases (GHGs) and to meet the ever increasing electricity demand. In South Africa, most energy is consumed by the industrial sectors when discretely compared to other sectors. Industrial consumers can reduce their electricity costs by creating an optimally managed onsite renewable energy system. Hydrokinetic is a promising renewable technology that has proved to offer a cost-effective electrification solution in areas with flowing water resources when compared to solar and wind technologies.

Research on Optimizing Operation of Hybrid PV Power and Pumped Hydro Storage System

Abstract: Considering the more and more capacity of PV generation installed in China. A model for optimizing operation of the hybrid PV power and pumped hydro storage system (PV-PHS) is proposed, which integrates and formulates operating factors such as the fuel cost, total unit start-up cost, and the pollutant discharge cost, etc. In this model, the objectives that optimization pursues include minimizing not only the overall operating cost but also the cost of PV energy curtailment. The optimization based on the IEEE-RTS 96 system is studied by applying the proposed model and the results prove it to be more adaptable and effective for the sustainable development of future power systems.

Portfolio Management and Stochastic Optimization in Discrete Time: An Application to Intraday Electricity Trading and Water Values for Hydroassets

Hydro storage system optimization is becoming one of the most challenging task in Energy Finance. Following the Blomvall and Lindberg (2002) interior point model, we set up a stochastic multiperiod optimization procedure by means of a ''bushy'' recombining tree that provides fast computational results. Inequality constraints are packed into the objective function by the logarithmic barrier approach and the utility function is approximated by its second order Taylor polynomial. The optimal solution for the original problem is obtained as a diagonal sequence where the first diagonal dimension is the parameter controlling the logarithmic penalty and the second is the parameter for the Newton step in the construction of the approximated solution. Optimimal intraday electricity trading and water values for hydroassets are computed. The algorithm is implemented in Mathematica.

California's renewable generation and pumped hydro storage's profitability

An analysis of 860 daily observations finds that rising renewable generation does not significantly diminish a pumped hydro storage system's daily operating profits from energy sales at the day-head and real-time market prices. The system, however, faces severely inadequate investment incentive because its annual operating profit can hardly pay for its annual fixed cost.

Wind-driven stand-alone DFIG with battery and pumped hydro storage system

A wind-driven doubly fed induction generator (DFIG) along with the battery and pumped hydro storage plant (PHSP) has been devised for supplying isolated loads. PHSP-based storage system is economical and viable for the MW level wind-turbine system. The proposed scheme employs a squirrel-cage induction machine (SCIM) coupled with reversible pump turbine for PHSP. The battery storage is also included in this system to cope up with the intermittent nature of wind and fast-changing load. A simple control strategy has been implemented for maintaining the set values of voltage magnitude and frequency at the stator terminals of DFIG, which serve as a virtual grid for connecting ac loads and SCIM. Based on the availability of power in the wind, PHSP and battery, various operating modes of the proposed system have been clearly identified for supplying the isolated loads. These operating modes are clearly demonstrated through the analysis developed for this purpose and validated through experimental results. The salient features of the proposed system over the existing stand-alone wind-driven generators are (i) structural simplicity, i.e., employing only one power electronic converter, (ii) wide speed operation of wind-driven DFIG, (iii) reduced battery capacity, (iv) high energy storage using PHSP and (v) availability of continuous power to the isolated loads.

Optimization of a wind powered desalination and pumped hydro storage system

The penetration of intermittent renewable energy sources, for instances wind power, in the power system of isolated islands is limited, even when there is large potential. The wind power that cannot be directly injected in the power grid is usually curtailed. In addition, some islands need to desalinate seawater to produce fresh water, increasing the pressure on the power system, because desalination needs electricity. Nevertheless, the water scarcity problem of an island can be part of the solution of the problem of its integration of intermittent renewable energy sources. To tackle this issue, a system was proposed to use the excess wind power in desalination units and in a pumped hydro storage, resulting in an integrated power and water supply system that would minimize the wind power curtailed. This paper proposes a methodology to optimize the size and operational strategy of this wind powered desalination and pumped hydro storage system. The objective is to minimize the total annualized production costs, maximize the percentage of renewable energy sources in the total power production and minimize the wind power curtailed. To solve this optimization problem, a derivative free multiobjective optimization method (Direct MultiSearch) is used. This methodology is applied to the integrated power and water supply system proposed for the island of S. Vicente, in Cape Verde. The results show that the penetration of renewable energy sources can reach 84% with a 27% decrease of power and water production costs and 67% decrease of CO2 emissions, in relation to the values foreseen for 2020.

Comparison of two energy storage options for optimum balancing of wind farm power outputs

This study presents a simple methodology for analysing and optimising combined wind generation and storage schemes, using both technical and economic performance criteria. The study provides a detailed analysis of the performance of two storage options for such a scheme: pumped storage hydro (PSH) and battery energy storage systems (BESSs). The analysis is carried out using recorded data from an actual UK wind farm (WF), information on the UK electricity market, and currently available PSH and BESS storage technologies to estimate and compare performance of the considered wind generation–storage schemes over the entire lifetime. The results show that an optimised generation–storage scheme can significantly reduce the variability of power outputs and increase the profitability of the WF. It is further shown that optimised PSH-based schemes have better economic performance than BESS schemes, as the latter are limited by the short discharge times. The approach developed in this study could be used during the initial design and planning stages, in order to select and optimise the type and size of energy storage for a combined wind generation–storage scheme.

Optimal scheduling for distributed hybrid system with pumped hydro storage

Photovoltaic and wind power generations are currently seen as sustainable options of in rural electrification, particularly in standalone applications. However the variable character of solar and wind resources as well as the variable load demand prevent these generation systems from being totally reliable without suitable energy storage system. Several research works have been conducted on the use of photovoltaic and wind systems in rural electrification; however most of these works have not considered other ways of storing energy except for conventional battery storage systems. In this paper, an energy dispatch model that satisfies the load demand, taking into account the intermittent nature of the solar and wind energy sources and variations in demand, is presented for a hybrid system consisting of a photovoltaic unit, a wind unit, a pumped hydro storage system and a diesel generator. The main purpose of the developed model is to minimize the hybrid system’s operation cost while optimizing the system’s power flow considering the different component’s operational constraints. The simulations have been performed using “fmincon” implemented in Matlab. The model have been applied to two test examples; the simulation results are analyzed and compared to the case where the diesel generator is used alone to supply the given load demand. The results show that using the developed control model for the proposed hybrid system, fuel saving can be achieved compared to the case where the diesel is used alone to supply the same load patters.

Sizing of a wind-hydro system using a reversible hydraulic facility with seawater. A case study in the Canary Islands

While the climatic conditions of the Canary Islands (Spain) are highly favourable for wind and solar energy exploitation, the low freshwater reserves are a problem when considering the implementation of hydro-based systems. For this reason, the pumped hydro storage (PHS) systems that have been proposed on the islands and which aim to exploit the available freshwater include an additional seawater desalination process.Given this drawback, this paper proposes an original alternative: a reversible PHS facility which directly uses seawater with the system in this case located on the coast of Gran Canaria island. This facility would be used to manage and better integrate the energy generated by a wind farm into a weak insular electrical system. An analysis is also undertaken of the economic benefits the proposed wind-hydro system would entail for the island’s electrical system.As a result of the incorporation of the hydraulic unit, the contribution of the wind-hydro system in satisfying electricity demand is 29% higher than if a wind-only system is used. The electrical energy generation cost of the wind-hydro system amounts to 95.34€/MWh, entailing an annual saving for the electrical system of 7.68M€/year.

Benchmarking and selection of Power-to-Gas utilizing electrolytic hydrogen as an energy storage alternative

Power-to-Gas is an energy storage and transportation technology which is useful for the development of the ‘smart grid’, including the integration of intermittent renewable energy sources through the provision of energy storage capacity. To accomplish this, surplus or intermittent power is used to produce hydrogen via water electrolysis. As hydrogen is an energy vector, converting the power into gaseous hydrogen is considered to be an effective energy storage alternative. Previous studies attempt to qualitatively compare energy storage technologies considering criteria such as market maturity, efficiency, and cost, and include energy storage systems such as electrochemical batteries, pumped hydro or compressed air energy storage systems. In this work an Analytical Hierarchy Process is applied to compare Power-to-Gas with other energy storage technologies in applications ranging from residential load shifting to bulk energy storage and utility-scale frequency support. The authors find that Power-to-Gas is desirable in utility scale energy storage applications where criteria such as energy portability, energy density and ability for seasonal storage are considered.

Optimization of the daily operation of a hydrokinetic–diesel hybrid system with pumped hydro storage

The present paper develops a model to optimize the daily operation of a hybrid energy system consisting of a hydrokinetic, a pumped hydro storage system and diesel generator. The optimization approach is aimed at minimizing the cost function subject to the availability of water resource, the variable load requirements, and operational constraints of the hybrid system’s components. The main purpose of the developed model is to minimize the daily amount of diesel fuel consumed to supply the load while maximizing the use of the hydrokinetic operating in conjunction with the pumped hydro storage. For simulation purposes, the hourly load demand, resource data for a selected rural area in South Africa have been collected and used as an input to the developed model. The economic analysis has resulted in the calculation of optimized daily operation cost of the proposed hybrid system in summer and winter conditions. The obtained results demonstrate that a substantial reduction in the daily operation cost can be achieved (88% in summer and 97% in winter) using the hybrid system compare to the case where the diesel generator is used alone.

Optimal Real-Time Scheduling for Hybrid Energy Storage Systems and Wind Farms Based on Model Predictive Control

Energy storage devices are expected to be more frequently implemented in wind farms in near future. In this paper, both pumped hydro and fly wheel storage systems are used to assist a wind farm to smooth the power fluctuations. Due to the significant difference in the response speeds of the two storages types, the wind farm coordination with two types of energy storage is a problem. This paper presents two methods for the coordination problem: a two-level hierarchical model predictive control (MPC) method and a single-level MPC method. In the single-level MPC method, only one MPC controller coordinates the wind farm and the two storage systems to follow the grid scheduling. Alternatively, in the two-level MPC method, two MPC controllers are used to coordinate the wind farm and the two storage systems. The structure of two level MPC consists of outer level and inner level MPC. They run alternatively to perform real-time scheduling and then stop, thus obtaining long-term scheduling results and sending some results to the inner level as input. The single-level MPC method performs both long- and short-term scheduling tasks in each interval. The simulation results show that the methods proposed can improve the utilization of wind power and reduce wind power spillage. In addition, the single-level MPC and the two-level MPC are not interchangeable. The single-level MPC has the advantage of following the grid schedule while the two-level MPC can reduce the optimization time by 60%.

Cost-effective design of ringwall storage hybrid power plants: A real options analysis

We study the economic viability and optimal sizing and siting of a hybrid plant that combines a ringwall hydro storage system with wind and solar power plants (ringwall storage hybrid power plant, RSHPP). A real options model is introduced to analyze the economics of an onshore RSHPP, and in particular of the varying storage volume in light of the stochastic character of wind and solar power, as well as the optimal investment timing under uncertainty. In fact, many uncertainties arise in such a project. Energy production is determined by the stochastic character of wind and solar power, and affects the optimal size of the storage device. Monte Carlo simulation is performed to analyze the following sources of uncertainty: (i) wind intensity and solar irradiation; (ii) future electricity price; and (iii) investment costs. The results yield the optimal size of the storage device; the energy market on which the operator should sell the electricity generated; numerical examples for two different RSHPP scenarios; and a real options model for analyzing the opportunity to defer the project investment and thus to exploit the value of waiting.

Cost-Effective Design of Ringwall Storage Hybrid Power Plants: A Real Options Analysis

We study the economic viability and optimal sizing and siting of a hybrid plant that combines a ringwall hydro storage system with wind and solar power plants (ringwall storage hybrid power plant, RSHPP). A real options model is introduced to analyze the economics of an onshore RSHPP, and in particular of the varying storage volume in light of the stochastic character of wind and solar power, as well as the optimal investment timing under uncertainty. In fact, many uncertainties arise in such a project. Energy production is determined by the stochastic character of wind and solar power, and affects the optimal size of the storage device. Monte Carlo simulation is performed to analyze the following sources of uncertainty: (i) wind intensity and solar irradiation; (ii) future electricity price; and (iii) investment costs. The results yield the optimal size of the storage device; the energy market on which the operator should sell the electricity generated; numerical examples for two different RSHPP scenarios; and a real options model for analyzing the opportunity to defer the project investment and thus to exploit the value of waiting.

Pumped storage-based standalone photovoltaic power generation system: Modeling and techno-economic optimization

Standalone renewable energy (RE) systems hold the most promising solution to the electrification of remote areas without utility grid access, while a feasible energy storage is a core part for achieving a continuous and reliable power supply since RE is usually intermittent and weather dependent. In the present study, the pumped hydro storage system is proposed, which is considered as a promising technology for solar energy penetration and particularly for small autonomous systems in remote areas. The mathematical models for the major components are developed, and system reliability and economic criteria are discussed as a benchmark for optimization. The genetic algorithm (GA), along with Pareto optimality concept, is used for the system techno-economic optimization: to maximize power supply reliability and minimize system lifecycle cost simultaneously. The proposed methodology is applied on a real remote inhabited island without power supply. System sizing, simulation and optimization are carried out using single-objective and double-objective GA technique. The performance of the optimal case under zero LPSP is examined. This study demonstrates that the proposed models and optimization algorithm is effective and can be used for other similar studies in the future.

A Novel Market Simulation Methodology on Hydro Storage

This paper presents a novel methodology to simulate the economic performance of hydro storage systems in the day-ahead (DA) and real-time (RT) markets. A detailed hydro storage system model is proposed to capture the unique characteristics of hydro storage units. A unique RT market bidding method named Tiered Bidding is proposed to represent the RT market offers of hydro storage units. In order to accurately represent the way hydro storage systems participate in the RT market, four hydro system RT bidding strategies are proposed and evaluated. The proposed methodology is applied to the Eastern Interconnection system to evaluate the economic benefits of Manitoba Hydro's market participation in MISO's RT energy and ancillary services market.

Hydraulic Hydro Storage System for Self-sufficient Cities

Many modern cities aspire renewable energy self-sufficiency. On a basic level, this can be achieved by producing enough solar and wind power to cover annual electricity demand. On a more ambitious level, the renewable power supply should cover consumption during every hour of the year. This could be reached by storing the energy in a local storage system with sufficient capacity. The Hydraulic Hydro Storage System is a solution to this ambitious level of self-sufficiency. It relies primarily on local resources and has an efficiency of 80%.

Cost-effective Design of Ringwall Storage Hybrid Power Plants: A Real Options Analysis

We study the economic viability and optimal sizing and siting of a hybrid plant that combines a ringwall hydro storage system with wind and solar power plants (ringwall storage hybrid power plant, RSHPP). A real options model is introduced to analyze the economics of an onshore RSHPP, an in particular of the varying storage volume in light of the stochastic character of wind and solar power, as well as the optimal investment timing under uncertainty. In fact, many uncertainties arise in such a project. Energy production is determined by the stochastic character of wind and solar power, and affects the optimal size of the storage device. Monte Carlo simulation is performed to analyze the following sources of uncertainty: (i) wind intensity and solar irradiation; (ii) future electricity price; and (iii) investment costs. The results yield the optimal size of the storage device; the energy market on which the operator should sell the electricity generated; numerical examples for two different RSHPP application scenarios; and a real options model for analyzing the opportunity to defer the project investment and thus to exploit the value of waiting.

Optimisation of Pumped-Hydro Storage System for Hybrid Power System Using Power Pinch Analysis

Storage technology in Hybrid Power System (HPS) is urgently required to adapt with the mismatch between the renewable energy (RE) production and the time distribution of load demands. Different storage systems incur different types and amount of losses depending on the power conditioning as well as storage system efficiencies. This work focuses on the design of HPS with pumped hydro storage systems using Power Pinch Analysis (PoPA). The previously developed modified Storage Cascade Table (SCT) for HPS with battery storage is adapted to calculate losses associated with the pumped hydro storage system. The demonstration of the method on an Illustrative Case Study shows that the application of pumped hydro storage in HPS yield lower total losses in the system. The maximum power demand target is reduced while the targeted maximum storage capacity is increased compared to when battery storage is applied.