Hydraulic Characterization of Variable-Speed Pump Turbine under Typical Pumping Modes

Shang, Linmin; Cao, Jingwei; Wang, Zhengwei; Liu, Xiaobing

doi:10.3390/pr11102903

Cited by 3 publications

(1 citation statement)

References 33 publications

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“…With the increasing significance of pump-turbine units in load regulation and frequency regulation tasks, along with accelerated adjustment cycles, the unit is more susceptible to operating at low flow rates during pump conditions. This further compromises the safety and stability of the unit [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Study on the Unsteady Flow Characteristics of a Pump Turbine in Pump Mode

Zhang,

Chen,

Han

et al. 2023

Processes

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Extensive research has been conducted on the performance of pump turbines, particularly focused on understanding the generation mechanism of S-shaped characteristics. However, there has been a lack of research on unsteady flow characteristics in hump characteristics with small guide vane openings. This study focuses on the hump characteristics of a pump turbine in pump mode. The unsteady numerical simulation method is used along with experimental testing to examine the internal flow characteristics and induced pressure fluctuations under pump operating conditions. The results indicate that flow separation occurs in the impeller when the flow rate decreases to the valley operating condition, and recirculation flow occurs near the impeller inlet at the partial flow rate. Moreover, the unstable flow on the positive slope exhibits a low-frequency characteristic of 0.15fn. The pressure fluctuation from the hub to shroud areas of the guide vane region diminishes sequentially. Notably, distinct vortex structures emerge at the draft tube cone section under the valley operating condition. These structures extend toward the elbow section of the draft tube as the flow rate decreases. This phenomenon generates low-frequency pressure fluctuation originating from the primary frequency of the vortex and dean vortex on the surface, located at 0.4 D of the draft tube under conditions of low flow rate.

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Section: Introductionmentioning

confidence: 99%

Study on the Unsteady Flow Characteristics of a Pump Turbine in Pump Mode

Zhang,

Chen,

Han

et al. 2023

Processes

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Quantifying power regulation characteristics in pump mode of variable‐speed pumped storage unit with DFIM

Liu,

Yang,

Yang

et al. 2024

Energy Science & Engineering

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Pumped storage plants (PSPs) play an important role in renewable energy consumption in power systems. Variable‐speed technology is a new and critical direction for the development of PSPs. In pump mode, variable‐speed pumped storage units (VSPSUs) have wider power regulation ranges and more flexible power responses than fixed‐speed pumped storage units (FSPSUs); however, the corresponding quantification study of VSPSUs is rare. Therefore, this study aims to quantify the static and dynamic power regulation characteristics of VSPSU in pump mode. First, the modeling of the fast speed control strategy of VSPSU in pump mode is improved. Then, the power regulation range of the VSPSU is explored. The factors (i.e., power command, governor, and converter) affecting the power response rapidity are quantified through the engineering case of a variable‐speed PSP adopting the doubly fed induction machine. Accordingly, suggestions on the settings of the parameters are provided. Quantification results show that parameter tuning based on this study effectively solves the problem of low regulation rate caused by great power fluctuations under typical power regulation cases in pump mode. This VSPSU has the fastest regulation rate of 13.75%/s when adjusting 40% power. This study could provide technical support to the practical operation of VSPSU.

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Research on the Flow Characteristics in the Gap of a Variable-Speed Pump-Turbine in Pump Mode

Wang,

et al. 2024

Processes

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A variable-speed pump-turbine is the core component of a hydraulic storage and energy generation station. When the pump-turbine operates at a constant speed, its response to the power grid frequency is poor. In order to improve the hydraulic efficiency of the pumped storage unit, variable-speed units are used. However, there has been no numerical study on the effect of the rotational flow characteristics within the gap of a variable-speed pump-turbine. This paper calculates the flow characteristics within the gap of a variable-speed pump-turbine under three typical pump modes (maximum head minimum flow condition, minimum head maximum flow condition, and maximum speed condition). The research results indicate that the rotational speed significantly affects the pressure distribution, velocity distribution, and turbulent kinetic energy distribution within the crown and band gaps. The higher the speed, the larger the area of the high-pressure region before the runner inlet compared to other operating conditions, and similarly, the low-pressure area after the runner outlet is also larger than in other operating conditions. The change in speed mainly affects the internal flow field of the crown gap, with the most noticeable changes occurring in the pressure and flow velocity at the inlet and outlet of the crown gap. There is a clear trend of pressure drop and velocity increase within the gap as the speed increases. However, with the increase in speed, the pressure distribution and flow velocity within the band gap remain almost the same. In addition to speed changes, it is observed that the pressure within the gap and the flow velocity within the passages are also related to the head, especially in the condition of maximum head, where this relationship becomes more noticeable.

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Hydraulic Characterization of Variable-Speed Pump Turbine under Typical Pumping Modes

Cited by 3 publications

References 33 publications

Study on the Unsteady Flow Characteristics of a Pump Turbine in Pump Mode

Study on the Unsteady Flow Characteristics of a Pump Turbine in Pump Mode

Quantifying power regulation characteristics in pump mode of variable‐speed pumped storage unit with DFIM

Research on the Flow Characteristics in the Gap of a Variable-Speed Pump-Turbine in Pump Mode

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