A method for estimating the pumping height of a low-head pumped storage power station in a single-tail pre-project river

Abstract

The application provides an estimation method for the suction height of a low-head pumped storage power station in a single tail water in a project early stage, comprising: in the project early stage, according to the unit parameters, the topography of the pumped storage power station and the waterway system arrangement conditions, the suction height required to meet the cavitation performance of the unit and the suction height required to meet the regulation guarantee performance of the unit are respectively estimated; and the smaller value is taken as the estimated suction height of the pumped storage power station. The application discloses an estimation method for the suction height of a low-head pumped storage power station in a single tail water in a project early stage, according to the unit parameters and the waterway arrangement of the pumped storage power station, the algorithm model is used, for the estimation of the suction height of the low-head pumped storage power station in the single-pipe single-unit arrangement of the tail water tunnel in the project early stage, sufficient accuracy and safety can be ensured, complex computer simulation can be avoided, the method is simple and easy to implement, and the work efficiency of the scheme arrangement in the project early stage can be greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pumped storage power station design, in particular to a method for estimating the suction height of a single-tail low-head pumped storage power station in the early stage of a project. BACKGROUND

[0002] At present, most of the pumped storage power stations that have been put into operation and are under construction are large in size, high in water head, deep in suction height, and adopt underground power houses. The depth of the suction height has little effect on the investment of the power station. However, the planning and site selection of small and medium-sized pumped storage power stations are being carried out. The single-machine capacity of small and medium-sized pumped storage power stations is small, and most of them are of medium and low water head. In order to reduce investment and construction period, ground or semi-underground power houses are preferred, and the tail water tunnel is short, and single-pipe single-machine arrangement is adopted. The suction height of the medium and low head unit will directly affect the layout type of the power house and the size of the slope excavation, and has a huge impact on the overall investment and construction period of the power station. Therefore, special attention should be paid to the selection of the suction height.

[0003] There are many site and hub combinations in the early stage of the project, and the depth of the survey and design is shallow. The hub layout is only a preliminary scheme, which has a certain degree of uncertainty. For the suction height of the power station, the existing empirical formula has too large error, and the computer simulation calculation has too large workload, and due to the uncertainty of the input boundary, the overall accuracy of the estimation of the suction height cannot be improved. Therefore, a simple and easy method is urgently needed to quickly estimate the suction height of the power station on the basis of ensuring the necessary accuracy. SUMMARY

[0004] In view of the defects in the prior art, the present application provides a method for estimating the suction height of a single-tail low-head pumped storage power station in the early stage of a project, which can effectively solve the above problems.

[0005] The technical scheme adopted by the present application is as follows:

[0006] The present application provides a method for estimating the suction height of a single-tail low-head pumped storage power station in the early stage of a project, which comprises the following steps:

[0007] Step S1, in the early stage of the project, for a medium and low head pumped storage power station with single-pipe single-machine arrangement of the tail water tunnel, according to the unit parameters, the topography of the pumped storage power station and the waterway system arrangement conditions, the suction height Hs 空化 required to meet the cavitation performance of the unit and the suction height Hs 调保 required to meet the regulation guarantee performance of the unit are respectively estimated.

[0008] Step S2, taking the suction height Hs 空化 required to meet the cavitation performance of the unit and the suction height Hs 调保the smaller value of P abs / (ρ·g) and P v / (ρ·g) as the estimated pump suction height of the pumped storage power station.

[0009] Preferably, the estimated pump suction height Hs 调保 required to meet the unit cavitation performance is obtained according to the formula (2) and formula (3) based on the unit rotation speed n, the unit pump working condition maximum head H and the flow rate Q corresponding to the unit pump working condition maximum head. 空化 , specifically:

[0010] Step A1, the specific speed n sp of the unit pump working condition is obtained according to the unit rotation speed n, the unit pump working condition maximum head H and the flow rate Q corresponding to the unit pump working condition maximum head by using formula (1). sp :

[0011] n sp = n·Q 0.5 / H 0.75 (1)

[0012] Step A2, the estimated pump suction height Hs 空化 required to meet the unit cavitation performance is obtained according to the specific speed n sp of the unit pump working condition, based on the unit operation without cavitation as the benchmark by using formula (2) and formula (3). 空化 :

[0013] Hs 空化 = P abs / (ρ·g)-P v / (ρ·g)±h LS -σ P ·H (2)

[0014]

[0015] wherein: P abs is the atmospheric pressure at the site of the pumped storage power station; ρ is the density of water passing through the pump turbine; g is the acceleration of gravity; P v is the vaporization pressure at the flow passage water temperature; h LS is the water head loss from the low pressure benchmark section to the lower reservoir inlet / outlet section; σ P is the cavitation coefficient of the pumped storage power station device.

[0016] Preferably, in the early stage of the project, P abs / (ρ·g) is 10.2m, P v / (ρ·g) is 0.2m, h LS is ignored due to the short tailrace tunnel, and formula (2) is simplified as:

[0017]

[0018] Preferably, the estimated pump suction height Hs 调保 required to meet the unit regulation guarantee performance is obtained according to the formula (4) and formula (5) based on the unit rotation speed n, the unit pump working condition maximum head H and the flow rate Q corresponding to the unit pump working condition maximum head.

[0019] Step B1, when the tailrace tunnel adopts a single-pipe single-unit layout, the principle is to ensure that the minimum pressure of the tailrace pipe is >-8m during the unit regulation process. Considering the correction of pressure pulsation and error, the formula (5) is obtained by fitting according to the length of the tailrace tunnel and the rated operating velocity of the tailrace tunnel turbine.

[0020]

[0021] Where: L is the length of the tailrace tunnel; v is the rated operating velocity of the tailrace tunnel turbine.

[0022] Step B2: Based on the actual rated operating velocity of the turbine in the tailrace tunnel, formula (5) is used to obtain the corresponding suction head Hs required to meet the unit's regulation and performance guarantee requirements. 调保 .

[0023] Preferably, in step B2, if the actual tailrace tunnel turbine rated operating velocity is different from the tailrace tunnel turbine rated operating velocity v in the segmented formula (5), then the suction head Hs corresponding to the actual tailrace tunnel turbine rated operating velocity is obtained by interpolation to meet the unit's regulation and performance requirements. 调保 .

[0024] The method for estimating the suction head of a single-tail low-head pumped storage power station in the early stage of a project, provided by this invention, has the following advantages:

[0025] This invention discloses a method for estimating the suction head of a low-head pumped storage power station in a single-tailrace tunnel during the early stages of a project. Based on the unit parameters and waterway layout of the pumped storage power station, the algorithm model of this invention estimates the suction head required to meet the cavitation and regulation requirements of the unit, and takes the smaller value as the required suction head of the power station. This invention provides sufficient accuracy and safety for estimating the suction head of a low-head pumped storage power station in a single-pipe, single-unit layout in the tailrace tunnel during the early stages of a project, while avoiding complex computer simulations. The method is simple and easy to implement, and can greatly improve the efficiency of determining the layout scheme in the early stages of a project. Attached Figure Description

[0026] Figure 1 A flowchart illustrating a method for estimating the suction height of a single-tailed low-head pumped storage power station in the early stages of a project, provided by this invention.

[0027] Figure 2 This is a schematic diagram illustrating the suction height required to ensure the performance of the unit's regulation, as provided by the present invention. Detailed Implementation

[0028] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the invention.

[0029] This invention discloses a method for estimating the suction head of a low-head pumped storage power station in a single-tailrace tunnel during the early stages of a project. Based on the unit parameters and waterway layout of the pumped storage power station, the algorithm model of this invention estimates the suction head required to meet the cavitation and regulation requirements of the unit, and takes the smaller value as the required suction head of the power station. This invention provides sufficient accuracy and safety for estimating the suction head of a low-head pumped storage power station in a single-pipe, single-unit layout in the tailrace tunnel during the early stages of a project, while avoiding complex computer simulations. The method is simple and easy to implement, and can greatly improve the efficiency of determining the layout scheme in the early stages of a project.

[0030] See Figure 1 This invention provides a method for estimating the suction head of a low-head pumped storage power station in single-tail water during the early stages of a project, comprising the following steps:

[0031] Step S1: In the early stage of the power station project, for a medium-low head pumped storage power station with a single-pipe, single-unit tailrace tunnel, the suction height Hs required to meet the cavitation performance of the unit is estimated based on the unit parameters, the topography of the pumped storage power station, and the layout conditions of the waterway system, taking into account the impact of cavitation and regulation performance. 空化 And the suction head Hs required to meet the unit's regulation and performance requirements. 调保 ;

[0032] The estimation yields the suction height Hs required to meet the cavitation performance of the unit. 空化 Specifically:

[0033] Step A1: Based on the unit speed n, the maximum head of the unit's water pump under operating conditions H, and the flow rate Q corresponding to the maximum head of the unit's water pump under operating conditions, the specific speed n of the unit's water pump under operating conditions is obtained using formula (1). sp :

[0034] n sp =n·Q 0.5 / H 0.75 (1)

[0035] Step A2, based on the specific speed n of the unit's water pump operating conditions. sp Based on the premise that no cavitation occurs during unit operation, the relationship between the cavitation coefficient and specific speed of existing medium-low head pumped storage power stations is analyzed and studied to obtain formulas (2) and (3). Using formulas (2) and (3), the suction height Hs required to meet the cavitation performance of the unit is estimated.空化 :

[0036] Hs 空化 =P abs / (ρ·g)-P v / (ρ·g)±h LS -σ P ·H (2)

[0037]

[0038] Where: P abs ρ is the atmospheric pressure at the location of the pumped storage power station, in Pa; ρ is the density of water passing through the pump and turbine, in kg / m³. 3 g is the acceleration due to gravity, m / s² 2 ;P v The vaporization pressure at the channel water temperature, Pa; h LS The head loss from the low-pressure reference section to the inlet / outlet section of the lower reservoir is given by m; σ P This represents the cavitation coefficient of a pumped storage power station.

[0039] In the early stages of a project, calculations can be simplified by taking P. abs / (ρ·g) is 10.2m, P v / (ρ·g) is 0.2m. Considering the relatively short tailrace tunnel, h LS Neglecting the consequences, formula (2) simplifies to:

[0040]

[0041] The required suction head Hs for the unit to meet regulation and performance requirements was estimated. 调保 Specifically:

[0042] Step B1, when the tailrace tunnel adopts a single-pipe single-unit layout, the principle is to ensure that the minimum pressure of the tailrace pipe is >-8m during the unit regulation process. Considering the correction of pressure pulsation and error, the formula (5) is obtained by fitting according to the length of the tailrace tunnel and the rated operating velocity of the tailrace tunnel turbine.

[0043]

[0044] Where: L is the length of the tailrace tunnel, m; v is the rated operating velocity of the tailrace tunnel turbine, m / s; in formula (5), Hs 调保 The unit is meters (m).

[0045] Formula (5) is derived by using a computer simulation program to calculate the tailrace tunnel length and the rated operating velocity of the tailrace tunnel turbine under various power station conditions. This yields the regulation and guarantee results of the unit under various combinations of the waterway system. The relationship between the tailrace tunnel length, the rated operating velocity of the tailrace tunnel turbine, and the suction head is summarized. After considering pressure pulsation and error correction, and taking the minimum tailrace pipe pressure > -8m as the benchmark during the unit regulation and guarantee process, Formula (5) is obtained. Its curve is shown in Figure 1. Figure 2 As shown, the suction head required by the unit to meet the regulation guarantee requirements can be estimated.

[0046] In step B2, if the actual tailrace tunnel turbine rated operating velocity is different from the tailrace tunnel turbine rated operating velocity v in the segmented formula (5), then the suction head Hs corresponding to the actual tailrace tunnel turbine rated operating velocity is obtained by interpolation, such as by using formulas or charts, to meet the unit's regulation and performance requirements. 调保 .

[0047] For example, if the actual rated operating velocity of the tailrace tunnel turbine is 2.8 m / s, then calculate Hs when v = 2.5 m / s. 调保 And Hs when v = 3.0 m / s 调保 Then, through interpolation, we obtain Hs at 2.8 m / s. 调保 .

[0048] Step B2: Based on the actual rated operating velocity of the turbine in the tailrace tunnel, formula (5) is used to obtain the corresponding suction head Hs required to meet the unit's regulation and performance guarantee requirements. 调保 .

[0049] Step S2, determine the suction height Hs required to meet the cavitation performance of the unit. 空化 And the suction head Hs required to meet the unit's regulation and performance requirements. 调保 The smaller value is used as the estimated suction height of the pumped storage power station.

[0050] This invention provides a method for estimating the suction height of a single-tailwater low-head pumped storage power station in the early stages of a project. It is applicable to pumped storage power stations with medium-low head and single-pipe single-unit layout in the tailrace tunnel, which are faced with a large number of station and hub layout combinations in the early stages of a project. Based on the unit parameters and waterway system layout conditions, and taking into account the impact of unit cavitation and regulation guarantee, the required suction height of the unit can be quickly estimated.

[0051] The following example, a pumped storage power station project that adopted the technical solution of this invention, further illustrates the point:

[0052] A pumped storage power station is equipped with two generating units, each with a capacity of 150MW. The maximum pump head under operating conditions is H = 240m, corresponding to a flow rate Q of 52m³ / h. 3 The tailrace system adopts a single-pipe, single-machine layout, with a single tailrace tunnel length L of 250m and a rated operating flow velocity v of 3m / s for the tailrace tunnel turbine.

[0053] Calculate the required extraction height to meet both cavitation and regulation requirements:

[0054] (1) Specific speed n of the unit's water pump under operating conditions sp :

[0055] n sp =n·Q 0.5 / H 0.75 =35.5mm 3 / s

[0056] (2) The suction height Hs required to meet the cavitation performance of the unit 空化 :

[0057]

[0058] (3) The suction height Hs required to meet the unit's regulation and performance guarantee requirements 调保 :

[0059] Hs 调保 =0.00004*L 2 -0.1259L - 10.6 = -39.6 (m)

[0060] (4) In summary, the smaller value of the two is taken, that is, the suction height is -39.6m.

[0061] The determination of the suction head for pumped storage power stations should simultaneously consider the impact of cavitation and regulation performance. Using existing empirical formulas to estimate the suction head required to meet cavitation requirements is problematic due to significant discrepancies between different formulas, making it unsuitable for direct design guidance. For regulation calculations, analytical formulas are outdated and simplistic, leading to excessively high estimation errors for pumped storage power station suction heads. Computer simulations, calculating each scheme individually, require numerous input boundary conditions, resulting in excessive computational load in the early stages of projects with a large number of site and scheme combinations. Furthermore, limitations in survey and design depth mean that the hub layout in the early stages is only a preliminary plan, and the uncertainty of input boundary conditions means that computer simulations cannot comprehensively improve the accuracy of suction head estimation. This invention, based on the analysis of actual parameters from multiple existing power stations, uses preliminary computer simulations to summarize the patterns in suction head estimation and proposes a method suitable for estimating the suction head of low-head pumped storage power stations in single-tailed-water configurations in the early stages of projects. This method ensures calculation accuracy while being convenient and easy to implement, significantly improving the accuracy and efficiency of determining system layout schemes in the early stages of projects, and has broad guiding and promotional significance.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for estimating the suction head of a single-tail low-head pumped storage power station in the early stages of a project, characterized in that, Includes the following steps: Step S1: In the early stage of the power station project, for a medium-low head pumped storage power station with a single-pipe, single-unit tailrace tunnel, the suction height Hs required to meet the cavitation performance of the unit is estimated based on the unit parameters, the topography of the pumped storage power station, and the layout conditions of the waterway system. 空化 And the suction head Hs required to meet the unit's regulation and performance assurance requirements. 调保 ; Step S2, determine the suction height Hs required to meet the cavitation performance of the unit. 空化 And the suction head Hs required to meet the unit's regulation and performance assurance requirements. 调保 The smaller value is used as the estimated suction height of the pumped storage power station; The estimation yields the suction height Hs required to meet the cavitation performance of the unit. 空化 Specifically: Step A1: Based on the unit speed n, the maximum head of the unit's water pump under operating conditions H, and the flow rate Q corresponding to the maximum head of the unit's water pump under operating conditions, the specific speed n of the unit's water pump under operating conditions is obtained using formula (1). sp : n sp =n·Q 0.5 / H 0.75 (1) Step A2, based on the specific speed n of the unit's water pump operating conditions. sp Based on the premise that no cavitation occurs during unit operation, the suction height Hs required to meet the cavitation performance of the unit is estimated using formulas (2) and (3). 空化 : Hs 空化 =P abs / (ρ·g)-P v / (ρ·g)±h LS -σ P ·H (2) Where: P abs The atmospheric pressure at the location of the pumped storage power station; ρ is the density of the water passing through the pump and turbine; g is the acceleration due to gravity; P v h is the vaporization pressure at the channel water temperature. LS σ represents the head loss from the low-pressure reference section to the inlet / outlet section of the lower reservoir; P The cavitation coefficient of a pumped storage power station device; In the early stages of the project, take P. abs / (ρ·g) is 10.2m, P v / (ρ·g) is 0.2m. Considering the relatively short tailrace tunnel, h LS Neglecting the consequences, formula (2) simplifies to: The required suction head Hs for the unit to meet regulation and performance requirements was estimated. 调保 Specifically: Step B1, when the tailrace tunnel adopts a single-pipe single-unit layout, the principle is to ensure that the minimum pressure of the tailrace pipe is >-8m during the unit regulation process. Considering the correction of pressure pulsation and error, the formula (5) is obtained by fitting according to the length of the tailrace tunnel and the rated operating velocity of the tailrace tunnel turbine. Where: L is the length of the tailrace tunnel; v is the rated operating velocity of the tailrace tunnel turbine. Step B2: Based on the actual rated operating velocity of the turbine in the tailrace tunnel, formula (5) is used to obtain the corresponding suction head Hs required to meet the unit's regulation and performance guarantee requirements. 调保 .

2. The method for estimating the suction head of a single-tail low-head pumped storage power station in the early stage of a project, as described in claim 1, is characterized in that... In step B2, if the actual tailrace tunnel turbine rated operating velocity is different from the tailrace tunnel turbine rated operating velocity v in the segmented formula (5), then the suction head Hs corresponding to the actual tailrace tunnel turbine rated operating velocity is obtained by interpolation to meet the unit's regulation and performance requirements. 调保 .

Images