Numerical Analysis of the Transient Behaviour of a Variable Speed Pump-Turbine during a Pumping Power Reduction Scenario

Pavesi, Giorgio; Cavazzini, Giovanna; Ardizzon, Guido

doi:10.3390/en9070534

Cited by 39 publications

(20 citation statements)

References 17 publications

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“…9). When the instabilities start up, forcing frequencies are highlighted and they partly coincide with those identified in the pumping power reduction scenario obtained by speed reduction (St=0.33, St=0.66) [16], but the most remarkable ones are related to the rotating stall phenomenon highlighted during the rapid closure of the wicket gates.…”

Section: Analysis Of Transient Flow In Pump Turbine During Wicket Gatmentioning

confidence: 99%

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Numerical investigation on transient flow of a high head pump-turbine in pump mode during rapid closure of guide vanes

Pavesi

Wang

2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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Transient flow in pump turbines appears because the hydropower storage plant needs to experience variable operation modes to make a balance between the electricity production and consumption, thus causing high-pressure fluctuations and shortening life expectancy. In this paper, three-dimensional numerical simulation, based on Detached Eddy Simulation (DES) turbulent model, was carried out to investigate the flow characteristics in a high head pump turbine in pump mode during rapid closure of wicket gates. The dynamic mesh technique was applied to simulate the rotation of the guide vane. In this work, the influence of water compressibility on pressure fluctuations was considered. The transient flow characteristics during load reduction were investigated by time-frequency analysis methods of the numerical data. KEYWORDS IntroductionLast decades have witnessed an increasing consumption of renewable energy due to the increasing price of fossil fuels and damage of carbon dioxide emissions on the living environment. The development of wind energy, solar power energy, hydropower energy and clean energy has been put into investigation for many years. However, it is a challenging task to control the stability of the output of renewable energy transmitted to the electricity grid because of stochastic nature of the renewable energy and fluctuating requirement of customers.In the renewable energy system, hydropower pump storage plant has been deemed as a costeffective electricity storage technology to balance the output of renewable electricity and need of the customers. Even though hydropower pump storage plants has such advantage, it needs change the operation modes between the pump mode and turbine mode frequently to meet the unpredictable need of electricity consumption, leading to transient instable flow in the pump-turbine under variable transient processes including the start-up, stop and adjusting rotating speed and so on. Besides, one of the common transient processes is that the wicket gates are required to open or close frequently. The transient instable flow including the flow separation, back flow and rotating stalls can cause severe pressure fluctuations, resulting in the vibrations of pump-turbine, even reducing the operating life expectancy and accidents. Thus, it is very important and urgent to investigate the transient flow mechanism for reducing the unstable flow [1].Many numerical and experimental investigations on the unsteady flow that are rotor-stator interaction and rotating stall have been carried out on pump-turbine at pump mode and turbine mode at the constant flow rate [2][3][4][5][6][7]. In terms of research on the transient process, the transient processes that are runaway, no-load, load rejection and so on are studied in pump turbine at turbine mode by numerical simulation and experimental methods. Cavazzini et al [8] simulated the transient flow in pump turbine at turbine mode under no-load condition. She pointed out that the head began to increase due to the fully developed rotating...

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Section: Analysis Of Transient Flow In Pump Turbine During Wicket Gatmentioning

confidence: 99%

“…Since the study was aimed at reproducing the load rejection scenario of a pump-turbine, a large adjustable guide vane opening of 23.4 deg, presenting an unstable behavior in pumping mode [16], was considered as starting configuration. Fig.…”

Section: Pump-turbine Modelmentioning

confidence: 99%

Numerical investigation on transient flow of a high head pump-turbine in pump mode during rapid closure of guide vanes

Pavesi

Wang

2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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“…During the dynamic process of extreme condition (i.e. load rejection or pump outage) with the non optimal closing law, the rise of the unit rotational speed and the water hammer pressure will exceed the maximum design value, which cause the runaway speed of the PSHU, abnormal vibration or active guide vane asynchronous and other negative phenomena [8,9]. OGVCS plays an important role in ensuring the security and stability of the power grid, and several methods have been proposed to deal with the OGVCS problem.…”

Section: Of 26mentioning

confidence: 99%

“…At present, the pump-turbine modeling based on the characteristic curves has been widely used. In this paper, pump-turbine is be described as the torque function and flow function of guide vane opening, generator rotational speed and water head, shown as formula (8) [32]. The analytic expression of nonlinear functions of ( ) m f ⋅ and ( ) q f ⋅ are difficult to obtain.…”

Section: Model Of Pshumentioning

confidence: 99%

Optimization of Guide Vane Closing Schemes of Pumped Storage Hydro Unit Using an Enhanced Multi-Objective Gravitational Search Algorithm

Zhou¹,

Xu²,

Zheng³

et al. 2017

Preprint

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Abstract：The optimization of guide vane closing schemes (OGVCS) of pumped storage hydro unit (PSHU) is the research field of cooperative control and optimal operation of pumped storage, wind power and solar power generation. This paper presents a OGVCS model of PSHU considering the rise rate of the unit rotational speed and the specific node pressure of each hydraulic unit, as well as various complicated hydraulic and mechanical constraints. OGVCS model is formulated as a multi-objective optimization problem to optimize conflictive objectives, i.e., unit rotational speed and water hammer pressure criteria. In order to realize the efficient solution of the OGVCS model, an enhanced multi-objective bacterial-foraging chemotaxis gravitational search algorithm (EMOBCGSA) is proposed to solve this problem, which adopts population reconstruction, adaptive selection chemotaxis operator of local searching strategy and Elite archive set to efficiently solve the multi-objective problem. Especially, novel constraints-handling strategy with eliminating and local search based on violation ranking is used to balance various hydraulic and mechanical constraints. Finally, simulation cases of complex extreme operating conditions (i.e., load rejection and pump outage) of 'single tube-double units' type PSHU system are conducted to verify the feasibility and effectiveness of the proposed EMOBCGSA in solving OGVCS problem. The simulation results indicate that the proposed EMOBCGSA can provide lower rise rate of the unit rotational speed and smaller water hammer pressure than other method established recently while considering various complex constraints in OGVCS problem.Keyword: pumped storage hydro unit; guide vane closing schemes; multi-objective optimization; enhanced multi-objective bacterial-foraging chemotaxis gravitational search algorithm (EMOBCGSA); hydraulic and mechanical constraints

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“…It has been reported that the intermittency and the variability of renewable energy resources can adversely affect flexibility [3]. To address this problem, the role of pumped hydroelectric storage (PHES) has received attention as a flexible resource; it has a fast start-up and ramping characteristics [4][5][6][7]. In Korea, the PHES start-up is 4 min, while those for a hot-start combined cycle gas turbine and hot-start coal steam turbine are 57 and 197 min, respectively.…”

Section: Introductionmentioning

confidence: 99%

Flexibility-Based Reserve Scheduling of Pumped Hydroelectric Energy Storage in Korea

Min

Kim

2017

Energies

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Abstract:The high penetration of renewable energy resources has made it harder to secure a flexible power system. Accordingly, this has become an issue in operating power systems. As a possible solution, pumped hydroelectric energy storage (PHES) has received much attention because of its fast start-up and ramp characteristics. This study proposes a flexibility-based reserve scheduling method for PHES. In this method, the reserve scheduling of PHES was conducted to improve flexibility; the associated risk index was termed the ramping capability shortage expectation (RSE). The peak-load days in 2016 and 2029 were selected to examine the applicability and performance of the proposed method. Results indicate that the proposed method can improve the flexibility by 4.45% for 2016 and 0.9% for 2029, respectively.

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Numerical Analysis of the Transient Behaviour of a Variable Speed Pump-Turbine during a Pumping Power Reduction Scenario

Cited by 39 publications

References 17 publications

Numerical investigation on transient flow of a high head pump-turbine in pump mode during rapid closure of guide vanes

Numerical investigation on transient flow of a high head pump-turbine in pump mode during rapid closure of guide vanes

Optimization of Guide Vane Closing Schemes of Pumped Storage Hydro Unit Using an Enhanced Multi-Objective Gravitational Search Algorithm

Flexibility-Based Reserve Scheduling of Pumped Hydroelectric Energy Storage in Korea

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