A method for setting the time constant of water hammer effect of hydraulic turbine and a real-time monitoring system

Abstract

The invention discloses a method for setting a time constant of a water hammer effect of a water turbine and a real-time monitoring system, and belongs to the technical field of parameter analysis of a water hammer effect of a water turbine. The method comprises: calculating the total head loss coefficient of a water diversion pipeline; obtaining the rated flow and rated head of a hydropower station; respectively monitoring the upstream water level, the downstream water level, the real-time water flow velocity in the pipeline and the flow velocity change rate of the hydropower station; and calculating the real-time value of the time constant of the water hammer effect of the water turbine. The invention solves the problem that the time constant of the water hammer effect of the water turbine changes with factors such as seasons and working conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of turbine water hammer effect parameter analysis, and in particular relates to a turbine water hammer effect time constant setting method and a real-time monitoring system. Background Art

[0002] In recent years, due to the urgent environmental problems and the growing demand for electricity, the penetration rate of renewable energy has increased rapidly. Hydropower stations are an important part of the renewable energy system. In addition to power generation, they also have multiple functions such as peak regulation, valley filling, frequency regulation, phase regulation, and emergency standby. However, when the working conditions of the turbine unit suddenly change, the guide vane opening will suddenly change, and the water pressure at each point of the water diversion pipeline will also change, so that the mechanical power input to the turbine will also change accordingly. When the guide vanes are suddenly opened, it will cause a trend of increasing flow, but the water pressure will decrease instead. The instantaneous power of the turbine does not increase but suddenly decreases, and then increases, and vice versa. Therefore, the severe water hammer caused by the emergency closure of the guide vanes may cause frequency oscillations to appear in the delivery system, seriously endangering the safe and stable operation of the power grid.

[0003] Water hammer effect time constant T W It can directly affect the parameter setting of the turbine speed governor and the frequency regulation performance of the unit, and T W It is strongly related to the operating conditions of the turbine and is not a constant. Current hydropower-related projects and research use default fixed values ​​in all seasons and under different operating conditions, which cannot accurately reflect the impact of water hammer effect on grid output power, frequency and other parameters. The field measurement method proposed in the field of scientific research requires separate load shedding test or governor input and output test, which will occupy certain resources. Therefore, the water hammer effect time constant T under normal operation is W Real-time monitoring and adjustment is an important and necessary task. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for setting the time constant of water hammer effect of a hydraulic turbine and a real-time monitoring system, which solves the problem that the time constant of water hammer effect of a hydraulic turbine varies with factors such as season and working conditions.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A method for setting a time constant of a water hammer effect of a hydraulic turbine comprises the following steps:

[0007] S1. Obtaining water diversion pipeline parameters, and calculating the head loss coefficient along the water diversion pipeline of the hydropower station and the local head loss coefficient according to the water diversion pipeline parameters, and obtaining the total head loss coefficient of the water diversion pipeline;

[0008] S2, obtaining the rated flow and rated head of the hydropower station;

[0009] S3, respectively monitoring the upstream water level, downstream water level, real-time water flow velocity in the pipeline and flow velocity change rate of the hydropower station;

[0010] S4. Calculate the real-time value of the water hammer effect time constant of the turbine based on the total head loss coefficient, the rated flow of the hydropower station, the rated head, the upstream water level of the hydropower station, the downstream water level, the real-time water flow velocity in the pipeline, and the flow velocity change rate.

[0011] The beneficial effects of the present invention are: in the wet and dry seasons and under different working conditions of the hydropower station, the operation data of the hydropower station can be monitored in real time, and within a certain error range, the approximate value of the water hammer effect time constant can be obtained through computer software. Compared with the default fixed value, the real-time monitoring and setting method can more accurately reflect the influence of the water hammer effect on the output power, frequency and other parameters of the power grid, and also help to better design the various parameters of the turbine governor, significantly improving the utilization rate of the hydropower station for water resources; compared with other proposed on-site measurement methods of the water hammer effect time constant, there is no need to conduct a separate load shedding or governor test, which can save a lot of operation and test costs.

[0012] Furthermore, the step S1 includes the following steps:

[0013] S101. Obtain the friction coefficient along the water supply pipeline by looking up the table according to the material of the water supply pipeline, and calculate the head loss coefficient along the water supply pipeline based on the length of the water supply pipeline, the diameter of the pipeline and the acceleration of gravity;

[0014] S102, analyzing and locating the pipeline section with local head loss according to the structural diagram of the hydropower pipeline, and based on the pipeline section, looking up the table to obtain the local resistance coefficient according to different pipeline shapes and pipeline parameters, and calculating the local head loss coefficient;

[0015] S103, calculating the total head loss coefficient of the water diversion pipeline according to the head loss coefficient along the water diversion pipeline and the local head loss coefficient.

[0016] The above further solution has the beneficial effect that the parameters for calculating the longitudinal and local head loss coefficients are directly obtained from the water diversion pipeline structure and building materials. Except for the case where the water diversion pipeline has structural changes, the total head loss coefficient generally remains constant, so it only needs to be calculated and determined at the initial stage of the hydropower station operation, and regularly checked and corrected on an annual basis, without the need for real-time monitoring.

[0017] Furthermore, the expression of the head loss coefficient along the way is as follows:

[0018]

[0019] Among them, α f represents the head loss coefficient along the way, λ represents the friction coefficient along the way, L represents the length of the water diversion pipeline, d represents the diameter of the water diversion pipeline, and g represents the acceleration of gravity;

[0020] The expression of the local head loss coefficient is as follows:

[0021]

[0022] n=1,2,3,...,m

[0023] Among them, α jn represents the local head loss coefficient, ξ n represents each local resistance coefficient, n represents the number of pipeline sections with local head loss, and m represents the total number of pipeline sections with local head loss;

[0024] The expression of the total head loss coefficient of the water diversion pipeline is as follows:

[0025] α w =α f +∑α jn

[0026] Among them, α w It represents the total head loss coefficient of the water diversion pipe, and ∑ represents the summation symbol.

[0027] The beneficial effect of the above further solution is that the total head loss coefficient of the same water diversion pipeline can be obtained by summing up the head loss coefficient along the pipeline and the local head loss coefficient. This calculation method conforms to the principle of hydraulics and basically has no error problem.

[0028] Furthermore, the expression of the real-time value of the water hammer effect time constant of the hydraulic turbine in step S4 is as follows:

[0029]

[0030] Among them, T W Indicates the real-time value of the time constant of the water hammer effect of the turbine, Q r Indicates the rated flow of the hydropower station, H u Indicates the real-time water level upstream, H d represents the real-time water level of the downstream, Q represents the real-time flow rate in the water diversion pipeline, α w It represents the total head loss coefficient of the water diversion pipeline, Indicates the flow rate change rate, H r Indicates rated head.

[0031] The beneficial effect of the above further scheme is that based on the momentum equation of the hydraulic system of the water diversion pipeline and the physical principle of the water hammer effect, the values ​​in the water hammer effect time constant calculation formula can be divided into three categories: rated value, constant value and real-time monitoring value. r and Q r is the rated value, H u , H d , Q and is the real-time monitoring quantity, α w It is a constant value calculated at the initial stage of operation of the hydropower station. Therefore, this setting formula is applicable to hydropower stations in various seasons and working conditions, and is basically not affected by the years of operation; it is not necessary to conduct a separate load rejection test or governor input and output test to obtain an approximate value of the water hammer effect time constant.

[0032] The present invention also provides a real-time monitoring system for a water hammer effect time constant of a hydraulic turbine, comprising:

[0033] The first calculation module is used to obtain the water diversion pipeline parameters, and calculate the head loss coefficient along the water diversion pipeline of the hydropower station and the local head loss coefficient according to the water diversion pipeline parameters, and obtain the total head loss coefficient of the water diversion pipeline;

[0034] An acquisition module, used to obtain the rated flow and rated water head of the hydropower station;

[0035] The monitoring module is used to monitor the upstream water level, downstream water level, real-time water flow velocity in the pipeline and flow velocity change rate of the hydropower station;

[0036] The second calculation module is used to calculate the real-time value of the water hammer effect time constant of the turbine based on the total head loss coefficient, the rated flow of the hydropower station, the rated head, the upstream water level of the hydropower station, the downstream water level, the real-time water flow velocity in the pipeline, and the flow velocity change rate.

[0037] The beneficial effects of the present invention are: in the wet and dry seasons and under different working conditions of the hydropower station, the operation data of the hydropower station can be monitored in real time, and within a certain error range, the approximate value of the water hammer effect time constant can be obtained through computer software. Compared with the default fixed value, the real-time monitoring and setting method can more accurately reflect the influence of the water hammer effect on the output power, frequency and other parameters of the power grid, and also help to better design the various parameters of the turbine governor, significantly improving the utilization rate of the hydropower station for water resources; compared with other proposed on-site measurement methods of the water hammer effect time constant, there is no need to conduct a separate load shedding or governor test, which can save a lot of operation and test costs.

[0038] Furthermore, the first calculation module includes:

[0039] The first calculation unit is used to obtain the friction coefficient along the water supply pipeline by looking up the table according to the material of the water supply pipeline, and calculate the head loss coefficient along the water supply pipeline based on the length of the water supply pipeline, the diameter of the pipeline and the acceleration of gravity;

[0040] The second calculation unit is used to analyze and locate the pipeline section with local head loss according to the structural diagram of the hydropower pipeline, and based on the pipeline section, according to different pipeline shapes and pipeline parameters, look up the table to obtain the local resistance coefficient, and calculate the local head loss coefficient;

[0041] The third calculation unit is used to calculate the total head loss coefficient of the water diversion pipeline according to the head loss coefficient along the water diversion pipeline and the local head loss coefficient.

[0042] The beneficial effect of the above further solution is: the total head loss coefficient α w According to the type of head loss, it is divided into the head loss coefficient along the way and multiple local head loss coefficients. After calculating each part separately and then summing them up, a more accurate total head loss coefficient α can be obtained. w In addition, when a part of the pipeline structure changes, the corresponding local or along-the-way head loss coefficient can be recalculated and then summed with other unchanged parts, rather than recalculating from scratch, to facilitate correction.

[0043] Furthermore, the expression of the head loss coefficient along the way is as follows:

[0044]

[0045] Among them, α f represents the head loss coefficient along the way, λ represents the friction coefficient along the way, L represents the length of the water diversion pipeline, d represents the diameter of the water diversion pipeline, and g represents the acceleration of gravity;

[0046] The expression of the local head loss coefficient is as follows:

[0047]

[0048] n=1,2,3,...,m

[0049] Among them, α jn represents the local head loss coefficient, ξ n represents each local resistance coefficient, n represents the number of pipeline sections with local head loss, and m represents the total number of pipeline sections with local head loss;

[0050] The expression of the total head loss coefficient of the water diversion pipeline is as follows:

[0051] α w =α f +∑α jn

[0052] Among them, α w It represents the total head loss coefficient of the water diversion pipe, and ∑ represents the summation symbol.

[0053] The beneficial effect of the above further solution is that the total head loss coefficient of the same water diversion pipeline can be obtained by summing up the head loss coefficient along the pipeline and the local head loss coefficient. This calculation method conforms to the principle of hydraulics and basically has no error problem.

[0054] Furthermore, the real-time numerical expression of the water hammer effect time constant of the hydraulic turbine is as follows:

[0055]

[0056] Among them, T W Indicates the real-time value of the time constant of the water hammer effect of the turbine, Q r Indicates the rated flow of the hydropower station, H u Indicates the real-time water level upstream, H u represents the real-time water level of the downstream, Q represents the real-time flow rate in the water diversion pipeline, α w It represents the total head loss coefficient of the water diversion pipeline, Indicates the flow rate change rate, H r Indicates rated head.

[0057] The beneficial effect of the above further scheme is: based on the momentum equation of the hydraulic system of the water diversion pipeline and the physical principle of the water hammer effect, the water hammer effect time constant calculation formula is obtained, and the values ​​in the formula can be divided into three categories: rated value, constant value and real-time monitoring value. r and Q r is the rated value, H u , H d , Q and is the real-time detection quantity, α w It is a constant value calculated at the beginning of the operation of the hydropower station. Therefore, this setting formula is applicable to hydropower stations in various seasons and working conditions, and is not affected by the years of operation; it is not necessary to conduct a separate load rejection test or governor input and output test to obtain an approximate value of the water hammer effect time constant.

[0058] Furthermore, the monitoring module includes: an upstream water level monitoring unit arranged in the upstream water reservoir, a downstream water level monitoring unit arranged below the tailwater pipe outlet, and a flow rate and flow rate change rate monitoring unit arranged at the water inlet; the upstream water level monitoring unit, the downstream water level monitoring unit, and the flow rate and flow rate change rate monitoring unit are all connected to a signal transmission unit connected to the control room of the hydropower station.

[0059] The beneficial effect of the above further scheme is that the installation position of the upstream and downstream water level monitoring units can directly obtain water level data, and the location is close to the hydropower station, which is convenient for energy supply and signal transmission. In addition, since the influence of the water hammer effect on the turbine frequency mainly occurs near the turbine guide vanes in the powerhouse, the flow rate and flow rate change rate monitoring unit is installed at the water inlet, which can be closer to the guide vanes and more accurately reflect the influence of the water hammer effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is the flow chart for setting the time constant of water hammer effect of turbine.

[0061] Figure 2 Schematic diagram of the hydropower station system and monitoring equipment.

[0062] Figure 3 It is a schematic diagram of the structure of the gradually expanding tube and the gradually contracting tube.

[0063] Figure 4 This is the structural block diagram of the real-time monitoring system for the water hammer effect time constant of a turbine.

[0064] Figure 5 Schematic diagram of the turbine governor model.

[0065] Figure 6 This is the equivalent circuit diagram of a single hydropower system.

[0066] Figure 7 For different T W Schematic diagram of the frequency response simulation results of the hydropower single-unit system.

[0067] Figure 8 This is a calculation table for local head loss in common elbows. DETAILED DESCRIPTION

[0068] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0069] like Figure 1 As shown, the present invention provides a method for setting the time constant of water hammer effect of a hydraulic turbine, and the implementation method thereof is as follows:

[0070] S1. Obtain the water diversion pipeline parameters, and calculate the head loss coefficient along the water diversion pipeline of the hydropower station and the local head loss coefficient according to the water diversion pipeline parameters, and obtain the total head loss coefficient of the water diversion pipeline. The implementation method is as follows:

[0071] S101. Obtain the friction coefficient along the water supply pipeline by looking up the table according to the material of the water supply pipeline, and calculate the head loss coefficient along the water supply pipeline based on the length of the water supply pipeline, the diameter of the pipeline and the acceleration of gravity;

[0072] S102, analyzing and locating the pipeline section with local head loss according to the structural diagram of the hydropower pipeline, and based on the pipeline section, looking up the table to obtain the local resistance coefficient according to different pipeline shapes and pipeline parameters, and calculating the local head loss coefficient;

[0073] In this embodiment, the management parameters are as follows: Figure 8 Pipe parameters such as diameter and angle of reducers and elbows.

[0074] S103, calculating the total head loss coefficient of the water diversion pipeline according to the head loss coefficient along the water diversion pipeline and the local head loss coefficient;

[0075] In this embodiment, in the hydraulic field, the head loss is divided into two categories according to different boundary conditions: for smooth boundaries, the head loss is proportional to the process flow, which is called the head loss along the process, and is expressed as h. f The head loss caused by the sudden change of local boundaries, which leads to the change of water flow structure, the change of flow velocity distribution and the generation of vortex area, is called local head loss, which is expressed by h. j express.

[0076] According to formula (1), the head loss h along the way is calculated f :

[0077]

[0078] Among them, λ is the friction coefficient along the way, L is the length of the water diversion pipeline, d is the diameter of the pipeline, v is the water flow velocity in the water diversion pipeline, and g is the acceleration of gravity.

[0079] Define the head loss coefficient α along the way f , so that it satisfies formula (2):

[0080]

[0081] Among them, h f is the head loss along the way, and Q is the water flow rate in the water diversion pipeline.

[0082] According to the definition formula of water flow and cylinder cross-sectional area, we can get formula (3):

[0083]

[0084] Among them, Q is the water flow rate in the water diversion pipeline, A is the cross-sectional area of ​​the water diversion pipeline, v is the water flow velocity in the water diversion pipeline, and d is the pipeline diameter.

[0085] Combining equations (1) to (3) gives the head loss coefficient α along the pipeline represented by the fixed parameters: f :

[0086]

[0087] Among them, λ is the friction coefficient along the way, L is the length of the water diversion pipeline, d is the diameter of the pipeline, and g is the acceleration of gravity.

[0088] In this embodiment, the local head loss is caused by the sudden change of the local boundary, which leads to the change of the water flow structure, the change of the flow velocity distribution and the generation of the vortex area. j In actual engineering, after the construction of a hydropower station is completed, the local head loss coefficient can be determined through drawings.

[0089] In this embodiment, the common structure of the water diversion pipeline of a hydropower station is as follows: Figure 2 As shown, H u is the upstream water level, H d is the downstream water level, h f is the head loss along the way, h jn is the local head loss at the nth location, and n is the number of the pipeline section with local head loss. The friction coefficient along the way in the head loss can be obtained by looking up the Moody diagram in "Hydraulics" according to the pipeline construction material and the roughness of the inner wall; for local head loss, such as the gradually expanding and contracting reducers at both ends and the elbows at any angle, the corresponding local resistance coefficient ξ can be obtained by looking up the table according to the pipeline shape and parameters n . Figure 3 It is a schematic diagram of the structure of the gradually expanding tube and the gradually contracting tube. Figure 3 In the table, D represents the diameter of the large end of the pipe, d represents the diameter of the small end of the pipe, v represents the direction of water flow, and θ represents the angle between the tapered pipes. Figure 8 It is the local resistance coefficient provided in "Hydraulics". Among them, Table 1 is the calculation table of local head loss of common reducers. Figure 8 This is a calculation table for local head loss in common elbows.

[0090] Table 1

[0091]

[0092] The local head loss h at the 1st to nth locations is calculated by formula (5): jn :

[0093]

[0094] Among them, ξ n is the local resistance coefficient, v is the water flow velocity in the water diversion pipe, and g is the gravitational acceleration.

[0095] Define each local head loss coefficient jn , so that it satisfies formula (6):

[0096]

[0097] Among them, h jn is the head loss along each part, and Q is the water flow rate in the water diversion pipeline.

[0098] Combining equations (3), (5) and (6) we can get the local head loss coefficient α represented by the fixed parameters of the pipeline: jn :

[0099]

[0100] Among them, ξ n are the local resistance coefficients, d is the pipe diameter, and g is the gravitational acceleration.

[0101] From the definition of total head loss, we can get formula (8):

[0102]

[0103] Among them, h f is the head loss along the way, is the sum of the local head losses of the 1st to mth sections, n represents the number of pipeline sections with local head losses, and m represents the total number of pipeline sections with local head losses;

[0104] Substituting formula (8) into formula (2), we can obtain:

[0105]

[0106] Where, f is the head loss coefficient along the way, It is the sum of the local head loss coefficients of sections 1 to m.

[0107] S2, obtaining the rated flow and rated head of the hydropower station;

[0108] S3, respectively monitoring the upstream water level, downstream water level, real-time water flow velocity in the pipeline and flow velocity change rate of the hydropower station;

[0109] S4. Calculate the real-time value of the water hammer effect time constant of the turbine based on the total head loss coefficient, the rated flow of the hydropower station, the rated head, the upstream water level of the hydropower station, the downstream water level, the real-time water flow velocity in the pipeline, and the flow velocity change rate.

[0110] In this embodiment, the real-time value of the water hammer effect time constant is calculated and determined based on the hydropower station parameters and the real-time monitoring quantity.

[0111] In this embodiment, combined with Figure 3, we can get the momentum equation of the hydraulic system as:

[0112]

[0113] Where, L is the total length of the water diversion pipeline, g is the acceleration of gravity, A is the cross-sectional area of ​​the pipeline, is the flow rate change rate, H u is the real-time water level upstream, H d is the real-time water level of the downstream, w is the total head loss coefficient of the water diversion pipeline, and Q is the real-time flow rate in the water diversion pipeline.

[0114] The dimensionless parameters are defined as follows:

[0115]

[0116] Among them, Q r is the rated flow rate, H r is the rated head, H is the measured head value, and Q is the measured flow value.

[0117] If the elasticity of the water diversion pipe is ignored, the mathematical expression of the water hammer effect of the rigid water diversion pipe is:

[0118]

[0119] Among them, Δh is the dimensionless parameter of the head change, T W is the water hammer effect time constant, is a dimensionless parameter of the flow rate change rate.

[0120] The dimensionless parameters in formula (12) are converted into field measured values:

[0121]

[0122] Among them, H r is the rated head, Q r is the rated flow rate, T W is the water hammer effect time constant, is the measured value of flow rate change rate.

[0123] In actual hydropower stations, the head change means the difference between the upstream and downstream water levels, minus the head loss in the water diversion pipeline, that is:

[0124] ΔH=H u -α w Q 2 -H d (14)

[0125] Among them, H u is the real-time water level upstream, H dis the real-time water level in the downstream, Q is the real-time flow in the water diversion pipeline, w It is the total head loss coefficient of the water diversion pipeline.

[0126] Combining equations (13) and (14), the real-time numerical calculation formula for the water hammer effect time constant can be obtained as follows:

[0127]

[0128] Among them, T W Indicates the real-time value of the time constant of the water hammer effect of the turbine, Q r Indicates the rated flow of the hydropower station, H u Indicates the real-time water level upstream, H u represents the real-time water level of the downstream, Q represents the real-time flow rate in the water diversion pipeline, α w It represents the total head loss coefficient of the water diversion pipeline, Indicates the flow rate change rate, H r Indicates rated head.

[0129] Example 2

[0130] like Figure 4 As shown, the present invention provides a real-time monitoring system for a water hammer effect time constant of a hydraulic turbine, comprising:

[0131] The first calculation module is used to obtain the water diversion pipeline parameters, and calculate the head loss coefficient along the water diversion pipeline of the hydropower station and the local head loss coefficient according to the water diversion pipeline parameters, and obtain the total head loss coefficient of the water diversion pipeline;

[0132] An acquisition module, used to obtain the rated flow and rated water head of the hydropower station;

[0133] The monitoring module is used to monitor the upstream water level, downstream water level, real-time water flow velocity in the pipeline and flow velocity change rate of the hydropower station;

[0134] The second calculation module is used to calculate the real-time value of the water hammer effect time constant of the turbine based on the total head loss coefficient, the rated flow of the hydropower station, the rated head, the upstream water level of the hydropower station, the downstream water level, the real-time water flow velocity in the pipeline, and the flow velocity change rate.

[0135] In one embodiment, the first calculation module comprises:

[0136] The first calculation unit is used to obtain the friction coefficient along the water supply pipeline by looking up the table according to the material of the water supply pipeline, and calculate the head loss coefficient along the water supply pipeline based on the length of the water supply pipeline, the diameter of the pipeline and the acceleration of gravity;

[0137] The second calculation unit is used to analyze and locate the pipeline section with local head loss according to the structural diagram of the hydropower pipeline, and based on the pipeline section, according to different pipeline shapes and pipeline parameters, look up the table to obtain the local resistance coefficient, and calculate the local head loss coefficient;

[0138] The third calculation unit is used to calculate the total head loss coefficient of the water diversion pipeline according to the head loss coefficient along the water diversion pipeline and the local head loss coefficient.

[0139] In one embodiment, the expression of the head loss coefficient along the way is as follows:

[0140]

[0141] Among them, α f represents the head loss coefficient along the way, λ represents the friction coefficient along the way, L represents the length of the water diversion pipeline, d represents the diameter of the water diversion pipeline, and g represents the acceleration of gravity;

[0142] The expression of the local head loss coefficient is as follows:

[0143]

[0144] n=1,2,3,...,m

[0145] Among them, α jn represents the local head loss coefficient, ξ n represents each local resistance coefficient, n represents the number of pipeline sections with local head loss, and m represents the total number of pipeline sections with local head loss;

[0146] The expression of the total head loss coefficient of the water diversion pipeline is as follows:

[0147] α w =α f +∑α jn

[0148] Among them, α w It represents the total head loss coefficient of the water diversion pipe, and ∑ represents the summation symbol.

[0149] In one embodiment, the real-time value of the water hammer effect time constant of the hydraulic turbine is expressed as follows:

[0150]

[0151] Among them, T W Indicates the real-time value of the time constant of the water hammer effect of the turbine, Q r Indicates the rated flow of the hydropower station, H u Indicates the real-time water level upstream, H urepresents the real-time water level of the downstream, Q represents the real-time flow rate in the water diversion pipeline, α w It represents the total head loss coefficient of the water diversion pipeline, Indicates the flow rate change rate, H r Indicates rated head.

[0152] In one embodiment, the monitoring module includes: an upstream water level monitoring unit arranged in the upstream water reservoir, a downstream water level monitoring unit arranged below the tailwater pipe outlet, and a flow rate and flow rate change rate monitoring unit arranged at the water inlet; the upstream water level monitoring unit, the downstream water level monitoring unit, and the flow rate and flow rate change rate monitoring unit are all connected to a signal transmission unit connected to the control room of the hydropower station.

[0153] In this embodiment, a single turbine system is used to verify the water hammer effect time constant T W The impact on the grid frequency, the turbine speed governor model is as follows Figure 5 As shown, T W The key role of the turbine speed governor is shown in the equivalent circuit diagram of the turbine single system. Figure 6 The system base capacity is 100MVA and the base voltage is 230kV. The turbine governor control parameters are set to K p =3.5, K i =2.7, K d =3, b p =0.05, T g =0.2, D=0.8, load parameters are P=100MW, Q=30Mvar. According to the operating principle of the turbine, the water hammer effect time constant T W By changing the transfer function of the speed regulator, the frequency regulation effect of the turbine is affected. W Set to 0.5s, 1.0s, 1.5s, 2s, 2.5s, based on Figure 6 The single-machine system shown in the figure is simulated in MATLAB / Simulink, and the load is set to increase by 30% at t=0s to obtain different T W The frequency response curve of the system is as follows: Figure 7 shown.

[0154] Depend on Figure 7 It can be seen that different T W The frequency response curves of the turbines are quite different, and the severity of oscillation increases with T W When T W =0.5s, 1.0s, 1.5s, 2.0s, the system frequency oscillates after a sudden load increase but gradually stabilizes; when T W = 2.5s, the frequency oscillation diverges and gradually intensifies. The simulation results show that TW The value of has a significant impact on the frequency stability and safe operation of the power system. A small difference in value will lead to obvious frequency deviation. However, in actual engineering and production, and even in the field of scientific research, most of the current work uses the T W It is regarded as a default fixed value, ignoring the objective reality that it changes with working conditions and seasons, resulting in large errors in the results of power grid operation analysis and scientific research. W The real-time monitoring and setting method starts from the fundamental principle of water hammer effect of hydraulic turbine and combines with the actual working needs of Southwest Power Grid to give T W Approximate accurate values ​​provide more accurate data support for hydropower frequency analysis problems.

[0155] like Figure 4 As shown, the real-time monitoring system for water hammer effect time constant of a hydraulic turbine provided in the embodiment can execute the technical solution shown in the real-time monitoring method for water hammer effect time constant of a hydraulic turbine in the above method embodiment, and its implementation principle and beneficial effects are similar and will not be repeated here.

[0156] In this embodiment, the present application can divide the functional units according to the real-time monitoring method of the water hammer effect time constant of the turbine. For example, each function can be divided into each functional unit, or two or more functions can be integrated into one processing unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. It should be noted that the division of units in the present invention is schematic and is only a logical division. There may be other division methods in actual implementation.

[0157] In this embodiment, in order to realize the principle and beneficial effect of the real-time monitoring method for the water hammer effect time constant of the water turbine, the real-time monitoring system for the water hammer effect time constant of the water turbine includes hardware structures and / or software modules corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the schematic units and algorithm steps described in the embodiments disclosed in the present invention, the present invention can be implemented in the form of hardware and / or a combination of hardware and computer software. Whether a function is executed in a hardware or computer software driven manner depends on the specific application and design constraints of the technical solution. Different methods can be used for each specific application to implement the described function, but such implementation should not be considered to exceed the scope of the present application.

[0158] Through the above design, the present invention can monitor and obtain the operation data of the hydropower station in real time during the wet and dry seasons and under different working conditions of the hydropower station, and obtain the approximate value of the water hammer effect time constant within a certain error range through computer software. Compared with directly taking the default fixed value, this real-time monitoring and setting method can more accurately reflect the impact of the water hammer effect on the power grid power, frequency and other parameters, which is helpful to design better turbine governor parameters and significantly improve the utilization rate of water resources in the hydropower station; compared with other proposed on-site measurement methods of the water hammer effect time constant, it does not need to conduct a separate load shedding or governor test, which can save a lot of operation and test costs.

[0159] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for setting the time constant of water hammer effect of a hydraulic turbine, characterized in that: The following steps are involved: S1. Obtaining water diversion pipeline parameters, and calculating the head loss coefficient along the water diversion pipeline of the hydropower station and the local head loss coefficient according to the water diversion pipeline parameters, and obtaining the total head loss coefficient of the water diversion pipeline; S2, obtaining the rated flow and rated head of the hydropower station; S3, respectively monitoring the upstream water level, downstream water level, real-time water flow velocity in the pipeline and flow velocity change rate of the hydropower station; S4. Calculate the real-time value of the water hammer effect time constant of the turbine according to the total head loss coefficient, the rated flow of the hydropower station, the rated head, the upstream water level of the hydropower station, the downstream water level, the real-time water flow velocity in the pipeline, and the flow velocity change rate; The expression of the real-time value of the water hammer effect time constant of the hydraulic turbine in step S4 is as follows: in, Indicates the real-time value of the time constant of the water hammer effect of the turbine. Indicates the rated flow of the hydropower station. Indicates the real-time water level upstream. Indicates the real-time flow rate in the water diversion pipeline. It represents the total head loss coefficient of the water diversion pipeline, represents the flow rate change rate, Indicates rated water head, H d Indicates the real-time water level height downstream.

2. The method for setting the time constant of water hammer effect of a hydraulic turbine according to claim 1, characterized in that: The step S1 comprises the following steps: S101. Obtain the friction coefficient along the water supply pipeline by looking up the table according to the material of the water supply pipeline, and calculate the head loss coefficient along the water supply pipeline based on the length of the water supply pipeline, the diameter of the pipeline and the acceleration of gravity; S102, analyzing and locating the pipeline section with local head loss according to the structural diagram of the hydropower pipeline, and based on the pipeline section, looking up the table to obtain the local resistance coefficient according to different pipeline shapes and pipeline parameters, and calculating the local head loss coefficient; S103, calculating the total head loss coefficient of the water diversion pipeline according to the head loss coefficient along the water diversion pipeline and the local head loss coefficient.

3. The method for setting the time constant of water hammer effect of a hydraulic turbine according to claim 2, characterized in that: The expression of the head loss coefficient along the way is as follows: in, represents the head loss coefficient along the way, represents the friction coefficient along the path, Indicates the length of the water diversion pipeline. Indicates the diameter of the water supply pipe. represents the acceleration due to gravity; The expression of the local head loss coefficient is as follows: in, represents the local head loss coefficient, represents each local resistance coefficient, The number of pipe sections representing local head losses, The total number of pipe sections representing local head losses; The expression of the total head loss coefficient of the water diversion pipeline is as follows: in, It represents the total head loss coefficient of the water diversion pipeline, Represents the summation symbol.

4. A real-time monitoring system for the time constant of water hammer effect of a hydraulic turbine, characterized in that: include: The first calculation module is used to obtain the water diversion pipeline parameters, and calculate the head loss coefficient along the water diversion pipeline of the hydropower station and the local head loss coefficient according to the water diversion pipeline parameters, and obtain the total head loss coefficient of the water diversion pipeline; An acquisition module, used to obtain the rated flow and rated water head of the hydropower station; The monitoring module is used to monitor the upstream water level, downstream water level, real-time water flow velocity in the pipeline and flow velocity change rate of the hydropower station; The second calculation module is used to calculate the real-time value of the water hammer effect time constant of the turbine according to the total head loss coefficient, the rated flow of the hydropower station, the rated head, the upstream water level of the hydropower station, the downstream water level, the real-time water flow velocity in the pipeline, and the flow velocity change rate; The real-time numerical expression of the water hammer effect time constant of the hydraulic turbine is as follows: in, Indicates the real-time value of the time constant of the water hammer effect of the turbine. Indicates the rated flow of the hydropower station. Indicates the real-time water level upstream. Indicates the real-time flow rate in the water diversion pipeline. It represents the total head loss coefficient of the water diversion pipeline, represents the flow rate change rate, Indicates rated water head, H d Indicates the real-time water level height downstream.

5. The real-time monitoring system for water hammer effect time constant of a hydraulic turbine according to claim 4, characterized in that: The first calculation module includes: The first calculation unit is used to obtain the friction coefficient along the water supply pipeline by looking up the table according to the material of the water supply pipeline, and calculate the head loss coefficient along the water supply pipeline based on the length of the water supply pipeline, the diameter of the pipeline and the acceleration of gravity; The second calculation unit is used to analyze and locate the pipeline section with local head loss according to the structural diagram of the hydropower pipeline, and based on the pipeline section, according to different pipeline shapes and pipeline parameters, look up the table to obtain the local resistance coefficient, and calculate the local head loss coefficient; The third calculation unit is used to calculate the total head loss coefficient of the water diversion pipeline according to the head loss coefficient along the water diversion pipeline and the local head loss coefficient.

6. The real-time monitoring system for water hammer effect time constant of a hydraulic turbine according to claim 5, characterized in that: The expression of the head loss coefficient along the way is as follows: in, represents the head loss coefficient along the way, represents the friction coefficient along the path, Indicates the length of the water diversion pipeline. Indicates the diameter of the water supply pipe. represents the acceleration due to gravity; The expression of the local head loss coefficient is as follows: in, represents the local head loss coefficient, represents each local resistance coefficient, The number of pipe sections representing local head losses, The total number of pipe sections representing local head losses; The expression of the total head loss coefficient of the water diversion pipeline is as follows: in, It represents the total head loss coefficient of the water diversion pipeline, Represents the summation symbol.

7. The real-time monitoring system for water hammer effect time constant of a hydraulic turbine according to claim 5, characterized in that: The monitoring module includes: an upstream water level monitoring unit arranged in the upstream water reservoir, a downstream water level monitoring unit arranged below the tailwater pipe outlet, and a flow rate and flow rate change rate monitoring unit arranged at the water inlet; the upstream water level monitoring unit, the downstream water level monitoring unit, and the flow rate and flow rate change rate monitoring unit are all connected to a signal transmission unit connected to the control room of the hydropower station.

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