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[en] Comprehensive conversion efficiency reflects the operation benefit of pumped storage power station. Analysing and studying the main influence factor for the comprehensive conversion efficiency is important to the overall design of power plant and to the improvement of comprehensive conversion efficiency. This paper adopts the method of combining field efficiency test with daily operation data analysis. By comparing and checking the test results with the model test results and the unit performance acceptance test results, the unit efficiency characteristics are defined. Through the analysis of daily operation data, the influence of unit operation mode on efficiency is clarified. Finally, it is concluded that the level of unit efficiency and generation operation mode are the main factors affecting the comprehensive conversion efficiency of power plants. (paper)
[en] This work addresses a new framework for self-scheduling of an individual price-taker pumped-storage plant in a day-ahead (DA) market. The goal is achieving the best trade-off between the expected profit and the risks when the plant participates in DA energy, spinning reserve and regulation markets. In this paper, a set of uncertainties including price forecasting errors and also the uncertainty of power delivery requests in the ancillary service markets are contemplated. Considering these uncertainties, a new approach is proposed which is called dynamic self-scheduling (DSS). This risk-constrained dynamic self-scheduling problem is therefore formulated and solved as a mixed integer programming (MIP) problem. Numerical results for a case study are discussed.
[en] Highlights: • We investigate unit commitment deploying stochastic and deterministic approaches. • We consider day-ahead markets, its forecast and weekly price based unit commitment. • Stochastic and deterministic unit commitment are identical for the first planning day. • Unit commitment and bidding policy can be based on the deterministic approach. • Robust forecasting models should be estimated based on the whole planning horizon. - Abstract: Pump storage plants are an important electricity storage technology at present. Investments in this technology are expected to increase. The necessary investment valuation often includes expected cash flows from future price-based unit commitment policies. A price-based unit commitment policy has to consider market price uncertainty and the information revealing nature of electricity markets. For this environment stochastic programming models are suggested to derive the optimal unit commitment policy. For the considered day-ahead price electricity market stochastic and deterministic unit commitment policies are comparable suggesting an application of easier implementable deterministic models. In order to identify suitable unit commitment and forecasting policies, deterministic unit commitment models are applied to actual day-ahead electricity prices of a whole year. As a result, a robust forecasting model should consider the unit commitment planning period. This robust forecasting models result in expected cash flows similar to realized ones allowing a reliable investment valuation
[en] Pumped storage power plants have long been used to regulate the production relative variations in consumption, but there is no preliminary pumping power plant in Norway built to regulate on short terms. To increase the knowledge about the possibilities to establish a pumping power plant in Norway, NVE has therefore been made a study of how pumping power can be drawn up and what it costs to build pumped storage plant between already existing magazine. One can not just based on cost and design conclude anything about the potential for pumped storage plant in Norway, but it is a start of a work that might make it easier to assess to what extent this may be possible. (eb)
[en] The head of pumped storage power station is usually set in a small range. When the water head changes in a wide range, it will lead to the reduction of turbine power efficiency and the life of hydraulic turbines. However, the limit of the range of water head change will result in the waste of reservoir capacity and limit the daily power generation. In order to increase the variation of water head in the design of power station, a pumped storage power station using virtual constant pressure tank is proposed in this paper. The concept of hydraulic constant pressure network is introduced. A virtual constant pressure tank is used as a hydraulic accumulator in a hydraulic constant pressure network. A group of hydraulic cylinders with different area ratios are used as hydraulic transformers. The water head of the large change in the reservoir is transformed into the head of the small and medium range in the virtual constant pressure tank through the hydraulic transmission mechanism, and then the power and storage of the pump/water turbine will be carried out. It ensures the efficient operation of the turbine and increases the capacity of sustainable power generation. (paper)
[en] Norway has great potential for producing pumped-storage hydropower, and the European Union (EU) hope Norway can contribute to Europe's transition to a renewable energy system by serving as a ‘green battery’. This is certainly technically feasible. However, this paper asks whether the green battery idea is politically feasible. The paper analyses four scenarios, three of which Norway serves as a green battery and one domestic. It focuses on decision-makers' and interest groups' positions on new interconnectors from Norway to continental Europe and the United Kingdom (UK), pumped-storage hydropower, and new renewable energy production in Norway. The paper argues that the present policy is characterised by incremental change—decisions about new interconnectors are made on an individual basis. Moreover the paper argues there is little reason to believe that this status quo policy will change based on any of the green battery scenarios in the near term. Still, decision-makers and interest groups are positive, in principle, towards new interconnectors and pumped-storage hydropower. Hence, Norway might become a green battery in the longer term. In the short term, however, a politically feasible contribution from Norway is balancing power through already existing hydropower capacity. - Highlights: ► Norwegian status quo policy is characterised by incremental change. ► Status quo is no likely to be replaced by a green battery scenario in the short term. ► Norway might become the green battery of Europe in the longer term
[en] Highlights: • The proposed model could obtain near-global optima in an acceptable CPU time. • The model performed well in relieving the peak shaving pressure of each power grid. • The piecewise linearization techniques described are novel and suitable. • The model has been integrated into the DSS for daily operation of PSHPs in ECPG. China's power grids have constructed many large pumped-storage hydropower plants (PSHPs) to relieve their increasing peak shaving pressure. Unlike PSHPs in a single power grid, the PSHPs directly operated by the dispatch center of regional power grids are required to simultaneously provide peak regulation services for several subordinate provincial power grids. This makes the daily operation of these PSHPs very challenging for both system operators and researchers. Hence, this paper develops a Mixed-integer linear programming (MILP) based model for determining the optimal hourly scheduling of PSHPs serving several provincial power grids. The objective is to minimize the peak-valley difference of the residual load series of each power grid. The performance of individual units in the model will be considered, as well as the head effect for each unit in both generating mode and pumping mode. The study focuses mainly on the linearization of the commonly-used nonlinear objective function, constraints on the operation status of units, and turbine performance curves. These nonlinearities are then linearized with the aid of binary integer variables. The optimization results obtained from two real-world case studies are used to demonstrate that the proposed model is computationally efﬁcient and shows good performance in relieving the peak regulation pressure of each power grid.
[en] Individual hydro- and thermal dominated electric power systems often have characteristics which make coordination between such systems inherently desirable. Operation- and design related differences call for interconnecting the two types of systems, e.g. by a 'pump-storage type' interplay between them. In this scheme the hydro-system can provide for required additional peak power and the necessary 'profiles' of production, while the thermal system covers new energy demand by increased energy production on the course of off-peak hours. Since energy represents one of the crucial building blocks in a modern society, all considerations concerning the development of coordinated systems of first of all focused on the functions and the economics efficiency of these systems and second on the technical solutions that have been developed. However, people have realized that they are part of a larger picture and that their well-being cannot be separated from that of nature. Power production from fossil burning and energy used can give about significant adverse environmental effects through emission into atmosphere of SO2, NOx, CO2, and particulates. The environmental aspects has more or less been neglected in the coordination process. Therefore the time in ripe to extend the discussion to include also environmental effects. The true least-cost solution to the utility operation- and planning problem can only be found by a consistent treatment of environmental effects in all steps of this problem. The paper gives an overview of the problem and demonstrates the environmental benefits from hydro-thermal coordination. (Author)
[en] The use of renewable energy sources has strongly increased in recent years. Because of the high volatility of these sources, an appropriate energy storage capacity as well as the provision of fast and flexible regulating power is necessary. Both can be supplied by pump storage power plants. The pump storage situation is Germany is discussed. The demand of energy storage is roughly estimated and the status quo of pump storage in Germany is described. Pump storage is compared to other storage technologies (compressed air storage, mobile batteries, hydrogen storage and power-to-gas storage) in terms of efficiency, response time and costs.