CN116107236A - Semi-physical simulation model test method for hydropower station transition process - Google Patents
Semi-physical simulation model test method for hydropower station transition process Download PDFInfo
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Abstract
The invention discloses a semi-physical simulation model test method for a hydropower station transient process, which comprises the following steps: 1) Establishing a similarity criterion of the model hydropower station and the prototype hydropower station; 2) Establishing a semi-physical simulation test model of the hydropower station transient process, and adopting a computer real-time simulation method to test the diversion system; adopting a physical model to carry out a test so as to obtain a more accurate internal state in the transition process of the water turbine; 3) And (5) performing a semi-physical simulation model test of the hydropower station transient process, and reversely calculating the change process of the related parameters of the prototype hydropower station. The method provided by the invention has the advantages of simple and convenient experimental process operation and high experimental result accuracy.
Description
Technical Field
The invention belongs to the technical field of hydropower station transition processes, and relates to a semi-physical simulation model test method for a hydropower station transition process.
Background
The safety accident of the hydropower station mainly occurs in the transient process of the hydropower station, and the improvement of the safety of the transient process of the hydropower station has important significance for guaranteeing the safety of the hydropower station. At present, the safety of the hydropower station in the transitional process is ensured mainly by a hydropower station transitional process calculation method, namely, the water pressure and flow change of the hydropower station in the transitional process in each position of a pipeline system are obtained through simulation calculation, so that the safety of the hydropower station in operation is judged.
However, because the internal flow state change of the water turbine in the transient process of the hydropower station is complex, the more detailed internal flow state change process of the water turbine is difficult to consider in the transient process calculation, so that the calculation result error is larger, the pumped storage hydropower station with higher water head is particularly obvious, and the potential threat is caused to the operation safety of the hydropower station.
Disclosure of Invention
The invention aims to provide a semi-physical simulation model test method for a hydropower station transient process, which solves the problem of large calculation result error caused by insufficient consideration of flow states in a water turbine in the hydropower station transient process calculation in the prior art.
The technical scheme adopted by the invention is that the semi-physical simulation model test method for the hydropower station transient process is implemented according to the following steps:
step 2, establishing a semi-physical simulation test model of the hydropower station transition process,
a computer real-time simulation method is adopted to test the diversion system; adopting a physical model to carry out a test so as to obtain a more accurate internal state in the transition process of the water turbine;
and step 3, performing a semi-physical simulation model test of the hydropower station transient process, and calculating the change process of the relevant parameters of the prototype hydropower station.
The method has the advantages that the similarity criteria of the model hydropower station and the prototype hydropower station are obtained through theoretical analysis, then a real model water turbine is adopted to carry out a transient process test according to the similarity criteria and hydropower station characteristics, a computer real-time simulation is adopted to carry out the transient process test on the water diversion system, and meanwhile, a system consisting of equipment such as a pressure tank, a vacuum tank, a high-pressure tank, an electromagnetic valve, a water pump, a check valve and the like is adopted to connect the computer real-time simulation system with the real model system of the water turbine, so that a semi-physical simulation model test method of the hydropower station transient process is formed. The method is simple and convenient to operate and high in accuracy.
Drawings
FIG. 1 is a schematic block diagram of a semi-physical simulation model test employed in the method of the present invention;
FIG. 2 is a schematic diagram of a prototype hydropower station arrangement for verification in an embodiment of the method of the invention;
FIG. 3 is a graph of the results of verification in an embodiment of the method of the present invention.
In the figure, 1. A high pressure tank; 2. a first electromagnetic valve; 3. manufacturing a first pressing tank; 4. a second electromagnetic valve; 5. a computer; 6. a third electromagnetic valve; 7. manufacturing a second pressing tank; 8. a fourth electromagnetic valve; 9. a vacuum tank; 10. a check valve I; 11. a water pump; 12. a first measuring device; 13. a hydraulic power unit; 14. a second measuring device; 15. and a second check valve.
Detailed Description
The invention will be described in detail below with reference to the drawings and the detailed description.
The semi-physical simulation model test method for the hydropower station transient process is implemented according to the following steps:
because the model water turbine and the prototype water turbine have the same unit parameters when working at similar working points, the model water turbine and the prototype water turbine have the following components:
in the formula (1), n 11 Is the unit rotation speed of the water turbine, Q 11 Is the unit flow of the water turbine, M 11 The unit moment of the water turbine is n is the rotating speed of the water turbine, H is the water head of the water turbine, Q is the flow of the water turbine, M is the moment of the water turbine, D is the nominal diameter of the water turbine, and subscripts are taken 1 All represent model water turbine parameters under similar working conditions, with subscripts 2 All represent prototype turbine parameters under similar conditions, and subscripts in the following expressions 1,2 In a similar manner to that described above,
the following formula is obtained after transformation from formula (1):
in formula (2), the scale relationship between the model water turbine and the prototype water turbine is assumed to be D 1 :D 2 ＝1:x D Then equation (2) is reconverted to:
in the formula (3), the following relation exists in the water diversion system according to the rigid water hammer model of the pipeline:
in the formula (4), h is the relative value of the water turbine head deviation, q is the relative value of the flow deviation, T w The inertial time constant of water flow of the water diversion system is adopted, and t is time;
after the secondary transformation, the expression of the obtained water flow inertia time constant is as follows:
in the formula (5), L is the length of the water diversion pipeline; a is the cross-sectional area of the water conduit, g is the gravitational acceleration,
because the model hydropower station and the prototype hydropower station work under similar working conditions, after the combined type (4) and the formula (5), the model hydropower station has the following steps:
in formula (6), subscript r Indicating the nominal operating condition, delta indicating the amount of deviation from the initial operating condition,
the difference of the formula (6) and the ratio of the two formulas are as follows:
because the working conditions of the model hydropower station are similar to those of the prototype hydropower station, the model hydropower station is transformed into:
when formula (8) is substituted into formula (7), there are:
assuming that the size ratio of the model to the prototype of the water diversion system is L 1 :L 2 ＝1:x L The time scale of the system transition process is t 1 :t 2 ＝1:x t The transformed expression of equation (9) is:
the combination of formula (3) and formula (10) is:
for local head loss, there are:
in the formula (12), xi is a local head loss coefficient, subscript J The partial head loss is expressed by the ratio of the two formulas in the formula (12) and the two formulas are arranged, and the method comprises the following steps:
in order to keep the working conditions of the prototype hydropower station and the model hydropower station similar in the dynamic process, the local loss water head in the diversion system is consistent with the specific scale of the water head of the water turbine, and the combined type (8), the formula (11) and the formula (13) are as follows:
for the pipeline along-path head loss, there are:
in the formula (15), lambda is the along-path head loss coefficient; d is the diameter of the water conduit; subscript of Y Indicating the head loss along the course,
the ratio of the two formulas of the formula (15) is adjusted, and the following are:
in order to keep the working conditions of the prototype hydropower station and the model hydropower station similar in the dynamic process, the along-path head loss in the diversion system should be kept consistent with the water turbine head scale, and the combined type (8), the formula (11) and the formula (16) are as follows:
according to the Xie Cai-Manning formula, the transformation is as follows:
in the formula (18), n c Is the roughness of the pipeline; r is the hydraulic radius of the pipeline,
the ratio of the two formulas of the formula (18) is adjusted, and the following are:
in the dynamic process of the water turbine, the rotation speed change must satisfy the following equation of motion:
in the formula (20), GD 2 Is the moment of a flywheel of the unit,
the ratio of the two formulas of the formula (20) is adjusted, and the following are:
the combination of formula (11) and formula (21) includes:
the turbine output must satisfy the following expression:
the combination of formula (11) and formula (23) includes:
the expression of the water hammer constructive is:
in the formula (25), a is the water hammer wave speed,
to ensure that the model hydropower station is similar to the prototype hydropower station in the dynamic process, the ratio of the water hammer to the time is kept consistent, and the method comprises the following steps:
from this, a similarity criterion of the model hydropower station and the prototype hydropower station is obtained, and the expression is:
step 2, establishing a semi-physical simulation test model of the hydropower station transition process,
the equation (27) can ensure that the transition process of the model hydropower station is similar to that of the prototype hydropower station, so that the model hydropower station has certain requirements on easily-controlled parameters such as system size, unit rotating speed, output and the like, and also has certain control requirements on the water hammer wave speed of a pipeline which is difficult to control; meanwhile, the characteristics of larger size of the pipeline system, large change of arrangement modes of different hydropower stations and high simulation precision of the pipeline transition process are considered, and a computer real-time simulation method is adopted to test the water diversion system; the characteristics of complex internal flow state and relatively small unit size in the transition process of the water turbine are considered, and a physical model is adopted for testing so as to obtain a more accurate internal state in the transition process of the water turbine.
Referring to fig. 1, a framework of a semi-physical simulation test model of a hydropower station transient process mainly comprises a high-pressure tank 1, a first pressure-making tank 3, a computer 5, a second pressure-making tank 7, a vacuum tank 9 and a hydropower set 13, wherein the high-pressure tank 1 is filled with high-pressure air, part of water and part of air are filled in the first pressure-making tank 3, the top of the first pressure-making tank 3 is simultaneously communicated with a first electromagnetic valve 2 and a second electromagnetic valve 4, the other end of the first electromagnetic valve 2 is communicated with the high-pressure tank 1, and the other end of the second electromagnetic valve 4 is connected with the atmosphere or the vacuum tank 9; one way of the bottom of the first pressure making tank 3 is connected with the outlet of the water pump 11 through a pipeline, the inlet of the water pump 11 is provided with the first check valve 10, the other way of the bottom of the first pressure making tank 3 is connected with the inlet of the volute of the hydraulic power unit 13, and the tail water pipe end of the hydraulic power unit 13 is connected with the bottom of the second pressure making tank 7; the second pressure making tank 7 is also filled with part of water and part of air, the bottom of the second pressure making tank 7 is additionally provided with a second check valve 15, the top of the second pressure making tank 7 is simultaneously communicated with a third electromagnetic valve 6 and a fourth electromagnetic valve 8, the other end of the third electromagnetic valve 6 is connected to the atmosphere or the high-pressure tank 1, and the other end of the fourth electromagnetic valve 8 is communicated with the vacuum tank 9; the first measuring device 12 is arranged at the inlet end of the volute of the hydraulic power unit 13, and the second measuring device 14 is arranged at the outlet end of the draft tube of the hydraulic power unit 13; the first measuring device 12 and the second measuring device 14 are connected to the signal input end of the computer 5 at the same time, and the signal output end of the computer 5 is connected with the first electromagnetic valve 2, the second electromagnetic valve 4, the third electromagnetic valve 6 and the fourth electromagnetic valve 8 at the same time.
The working principle of the hydropower station transient process semi-physical simulation test is as follows: a mathematical model of the diversion system is built in the computer 5, wherein the mathematical model comprises, but is not limited to, a mathematical model for solving pipeline water hammer by adopting a characteristic line method, a mathematical model for solving pipeline water hammer by adopting a wave characteristic method, or a mathematical model for solving pipeline water hammer by adopting an analytical function method, and the mathematical model comprises all the models of the overflow parts from an upstream water tank to a water turbine inlet and all the models of the overflow parts from a water turbine outlet to a downstream water channel, and the water turbine inlet and the water turbine outlet are boundary conditions of the mathematical model.
The method comprises the steps that real-time water pressure and flow at the inlet of a water turbine are obtained through a first measuring device 12, measured values are transmitted to a computer 5, the computer 5 takes the flow obtained through the first measuring device 12 as the boundary of an overflow part model from an upstream water reservoir to the inlet of the water turbine, the real-time water pressure at the inlet of the water turbine is obtained through calculation and is compared with the water pressure obtained through the first measuring device 12, when the water pressure obtained through measurement of the first measuring device 12 is lower than the calculated real-time water pressure, the computer 5 controls a first electromagnetic valve 2 to be opened and a second electromagnetic valve 4 to be closed, at the moment, compressed air in a high-pressure tank 1 enters a first pressure making tank 3, a first check valve 10 is closed, water loss in the first pressure making tank 3 is prevented, and the water pressure value at the inlet of the water turbine is improved; when the water pressure measured by the measuring device I12 is higher than the real-time water pressure obtained by calculation, the computer 5 controls the electromagnetic valve I2 to be closed and the electromagnetic valve II 4 to be opened, at the moment, compressed air in the pressure generating tank 3 is discharged out of the pressure generating tank, the water pressure value at the inlet of the water turbine is reduced, and the water pressure at the inlet of the water turbine is further guaranteed to be equal to the calculated water pressure of the computer 5 in real time;
meanwhile, the real-time water pressure and flow at the outlet of the water turbine are obtained through the second measuring device 14, the measured value is transmitted to the computer 5, the computer 5 takes the flow obtained by the second measuring device 14 as the boundary of the model of the flow passing component from the outlet of the water turbine to the downstream river, the real-time water pressure at the outlet of the water turbine is obtained by calculation, the real-time water pressure is compared with the water pressure obtained by the second measuring device 14, when the water pressure obtained by the second measuring device 14 is lower than the real-time water pressure obtained by calculation, the computer 5 controls the electromagnetic valve III 6 to be opened and the electromagnetic valve IV 8 to be closed, and at the moment, the air enters the pressure making tank II 7 through the electromagnetic valve III 6, and the water pressure value at the outlet of the water turbine is improved; when the water pressure obtained by measurement of the second measuring device 14 is higher than the real-time water pressure obtained by calculation, the computer 5 controls the electromagnetic valve III 6 to be closed and the electromagnetic valve IV 8 to be opened, air in the pressure making tank II 7 enters the vacuum tank, the check valve II 15 is closed at the moment, tail liquid is prevented from entering the pressure making tank II to cause failure in pressure reduction, the water pressure value at the outlet of the water turbine is reduced, and further the water pressure at the outlet of the water turbine is guaranteed to be equal to the calculated water pressure of the computer 5 in real time.
Step 3, semi-physical simulation model test of hydropower station transition process is carried out,
3.1 Solving the key parameters of the model hydropower station,
hydraulic turbine scale x for determining prototype hydropower station and model hydropower station D Water diversion system scale x L Transient time scale x t Calculating the length L of each water conduit of the model hydropower station according to the related parameters of the prototype hydropower station (27) 2 Diameter d of each water diversion pipeline of model hydropower station 2 Local head loss coefficient xi of each place in model hydropower station water diversion system 2 Roughness n of each section of pipeline in model hydropower station water diversion system c2 Water hammer wave speed a of pipelines of water diversion system of model hydropower station 2 Nominal diameter D of model hydropower station hydroturbine 2 Model hydropower station head H 2 Model hydropower station unit flow Q 2 Model hydropower station unit rotating speed n 2 Model hydropower stationUnit torque M 2 Unit flywheel moment of model hydropower station
Model hydropower station hydroturbine output P 2 ；
3.2 A related parameter of the test stand is set,
determining unit data of a model hydropower station of a test stand, including the nominal diameter D of a water turbine of the model hydropower station 2 Water head H of model hydropower station 2 Unit flow Q of model hydropower station 2 Unit rotation speed n of model hydropower station 2 Unit torque M of model hydropower station 2 Unit flywheel moment of model hydropower station
Water turbine output P of model hydropower station 2 ；
Setting related parameters of a model hydropower station water diversion system in a computer 5, wherein the related parameters comprise the length L of each water diversion pipeline of the model hydropower station 2 Diameter d of each water diversion pipeline of model hydropower station 2 Local head loss coefficient xi of each place in model hydropower station water diversion system 2 Roughness n of each section of pipeline in model hydropower station water diversion system c2 Water hammer wave speed a of pipelines of water diversion system of model hydropower station 2 。
3.3 A transition process test of the model hydropower station is carried out,
according to the transient process time scale x of the model hydropower station t And calculating the guide vane movement rule of the model hydropower station, measuring the rotating speed of the model hydropower station unit, the water pressure of the volute, the water pressure of the draft tube and the flow state change process in the water turbine by applying similar disturbance in the model hydropower station, and reversely calculating the change process of the relevant parameters of the prototype hydropower station according to a formula (27).
Simulation verification:
in order to verify the effectiveness of the method, a hydropower station is taken as an example for simulation calculation verification, a diversion system in the simulation adopts a characteristic line method to solve a water hammer basic equation, a water turbine adopts a model comprehensive characteristic curve to interpolate, so that the constraint of a formula (27) can be met in a large-range transition process of the hydropower set, and the abrupt 100% load shedding transition process of the set is simulated.
Referring to FIG. 2, a schematic diagram of the field layout of a prototype hydropower station is shown, the rated rotational speeds of the 1# unit and the 2# unit are 214.3r/min, the rated output is 266.7MW, and the diameters of the rotating wheels are 4.36m; the length of the No. 1 pipeline is 550m, the diameter of the No. 1 pipeline is 15m, the roughness of the No. 1 pipeline is 0.012,1, the local head loss coefficient at the inlet of the No. 1 pipeline is 0.1, and the water hammer wave speed of the No. 1 pipeline is 1200m/s; the length of the 2# pipeline is 20m, the diameter of the 2# pipeline is 15m, the roughness of the 2# pipeline is 0.012,2# pipeline, the local head loss coefficient at the inlet of the 2# pipeline is 0, and the water hammer wave speed of the 2# pipeline is 1200m/s; the sizes and parameters of the 3# pipeline, the 4# pipeline, the 5# pipeline and the 6# pipeline are the same, the lengths of the pipelines are 20m, the diameters of the pipelines are 10m, the roughness of the pipelines are 0.012, the local head loss coefficients at the inlets of the pipelines are 0, and the water hammer wave speeds of the pipelines are 1200m/s; the length of the 7# pipeline is 20m, the diameter of the 7# pipeline is 15m, the roughness of the 7# pipeline is 0.012,7# pipeline, the local head loss coefficient at the inlet of the 7# pipeline is 0, and the water hammer wave speed of the 7# pipeline is 1200m/s; the length of the 8# pipeline is 200m, the diameter of the 8# pipeline is 15m, the roughness of the 8# pipeline is 0.012,8# pipeline, the local head loss coefficient at the inlet of the 8# pipeline is 0, and the water hammer wave speed of the 8# pipeline is 1200m/s; the local head loss coefficient at the branch pipe from the 2# pipeline to the 3# pipeline and the 5# pipeline is 1, the local head loss coefficient at the converging pipe from the 4# pipeline and the 6# pipeline to the 7# pipeline is 1.5, the rated head of the hydropower station is 202m, and the flywheel moment GD of the 1# unit and the 2# unit 2 Are all 2X 10 5 t·m 2 The guide vane adopts a section of closing rule that the guide vane is closed by 100% for 20s after load shedding.
The water turbine size scale of the model hydropower station and the prototype hydropower station is selected to be 1:10, the water diversion system size scale is selected to be 1:80, and the time scale is selected to be 1:0.5, namely x in the formula (27) D ＝10，x L ＝80，x t =0.5, in this case according to formula (27), there is: the rated rotation speed of the unit of the model hydropower station is 857.2r/min, the rated output is 1707kW, the diameter of a rotating wheel is 0.433 m, the length of a No. 1 pipeline is 6.875m, the diameter of the No. 1 pipeline is 0.1875m, the roughness of the No. 1 pipeline is 0.0075,1, and the local head loss coefficient at the inlet of the No. 1 pipeline is 2.44X10 -5 The water hammer wave speed of the No. 1 pipeline is 7.5m/s; the length of the 2# pipeline is 0.25m, the diameter of the 2# pipeline is 0.1875m, the roughness rate of the 2# pipeline is 0.0075, the local head loss coefficient at the inlet of the 2# pipeline is 0, and the water hammer wave speed of the 2# pipeline is 7.5m/s; the lengths of the 3# pipeline, the 4# pipeline, the 5# pipeline and the 6# pipeline are 0.25m, the 3# pipeline, the 4# pipeline, the 5# pipeline and the 6# pipeline are 0.125m in diameter, the 3# pipeline, the 4# pipeline, the 5# pipeline and the 6# pipeline are 0.0075 in roughness rate, the local head loss coefficients at the inlets of the 3# pipeline, the 4# pipeline, the 5# pipeline and the 6# pipeline are 0, the 3# pipeline, the 4# pipeline, the 5# pipeline and the 6# pipeline are 7.5m/s in water hammer wave speed; the length of the 7# pipeline is 0.25m, the diameter of the 7# pipeline is 0.1875m, the roughness of the 7# pipeline is 0.0075,7# pipeline, the local head loss coefficient at the inlet of the 7# pipeline is 0, and the water hammer wave velocity of the 7# pipeline is 7.5m/s; the length of the 8# pipeline is 2.5m, the diameter of the 8# pipeline is 0.1875m, the roughness of the 8# pipeline is 0.0075,8# pipeline, the local head loss coefficient at the inlet of the 8# pipeline is 0, and the water hammer wave speed of the 8# pipeline is 7.5m/s; the local head loss coefficient at the branching pipe from the 2# pipe to the 3# pipe and the 5# pipe was 2.44X10 -4 The local head loss coefficient at the converging pipe converging from the 4# pipe and the 6# pipe to the 7# pipe was 3.66×10 -4 The method comprises the steps of carrying out a first treatment on the surface of the Rated water head of hydropower station is 32.32m, flywheel moment GD of No. 1 unit and No. 2 unit 2 Are all 16 t.m 2 The guide vane adopts a section of closing rule that the load is thrown and the guide vane is closed for 100% by 40 s.
The hydraulic power unit of the model hydropower station and the hydraulic power unit of the prototype hydropower station generate a 100% load dump transition process, the rotational speed of the model hydropower station, the inlet pressure of the water turbine, the outlet pressure of the water turbine and the position of the guide vane are converted to the prototype hydropower station according to a formula (27), and the result is compared with the simulation result of the prototype hydropower station, and is shown in fig. 3. As can be seen from fig. 3, the simulation data of the model hydropower station overlap with the simulation data of the prototype hydropower station, which indicates that the transient process corresponding to the prototype hydropower station can be completely reflected by adopting the model hydropower station test.
As can be seen from FIG. 3, the dynamic process of the model hydropower station can fully represent the dynamic process of the prototype hydropower station, which illustrates the semi-physical simulation model test method of the hydropower station transient process of the invention, and the dynamic process of the prototype hydropower station can be represented by the test of the model hydropower station.
Claims (5)
1. A semi-physical simulation model test method for a hydropower station transient process is characterized by comprising the following steps:
step 1, establishing a similarity criterion of a model hydropower station and a prototype hydropower station;
step 2, establishing a semi-physical simulation test model of the hydropower station transition process,
a computer real-time simulation method is adopted to test the diversion system; adopting a physical model to carry out a test so as to obtain a more accurate internal state in the transition process of the water turbine;
and step 3, performing a semi-physical simulation model test of the hydropower station transient process, and calculating the change process of the relevant parameters of the prototype hydropower station.
2. The hydropower station transient semi-physical simulation model test method according to claim 1, wherein in step 1, the specific process is:
because the model water turbine and the prototype water turbine have the same unit parameters when working at similar working points, the model water turbine and the prototype water turbine have the following components:
in the formula (1), n 11 Is the unit rotation speed of the water turbine, Q 11 Is the unit flow of the water turbine, M 11 The unit moment of the water turbine is n is the rotating speed of the water turbine, H is the water head of the water turbine, Q is the flow of the water turbine, M is the moment of the water turbine, D is the nominal diameter of the water turbine, and subscripts are taken 1 All represent model water turbine parameters under similar working conditions, with subscripts 2 All represent prototype turbine parameters under similar conditions, and subscripts in the following expressions 1,2 In a similar manner to that described above,
the following formula is obtained after transformation from formula (1):
model water turbineThe scale relationship of the prototype water turbine is D 1 :D 2 ＝1:x D Then equation (2) is reconverted to:
aiming at the water diversion system, according to the rigid water hammer model of the pipeline, the water diversion system has the following relation:
in the formula (4), h is the relative value of the water turbine head deviation, q is the relative value of the flow deviation, T w The inertial time constant of water flow of the water diversion system is adopted, and t is time;
after the secondary transformation, the expression of the obtained water flow inertia time constant is as follows:
in the formula (5), L is the length of the water diversion pipeline; a is the cross-sectional area of the water conduit, g is the gravitational acceleration,
because the model hydropower station and the prototype hydropower station work under similar working conditions, after the combined type (4) and the formula (5), the model hydropower station has the following steps:
in formula (6), subscript r Indicating the nominal operating condition, delta indicating the amount of deviation from the initial operating condition,
the difference of the formula (6) and the ratio of the two formulas are as follows:
because the working conditions of the model hydropower station are similar to those of the prototype hydropower station, the model hydropower station is transformed into:
when formula (8) is substituted into formula (7), there are:
assuming that the size ratio of the model to the prototype of the water diversion system is L 1 :L 2 ＝1:x L The time scale of the system transition process is t 1 :t 2 ＝1:x t The transformed expression of equation (9) is:
the combination of formula (3) and formula (10) is:
for local head loss, there are:
in the formula (12), xi is a local head loss coefficient, subscript J Indicating the loss of the local head of water,
the ratio of the two formulas in the formula (12) is adjusted, and the following are:
in order to keep the working conditions of the prototype hydropower station and the model hydropower station similar in the dynamic process, the local loss water head in the diversion system is consistent with the specific scale of the water head of the water turbine, and the combined type (8), the formula (11) and the formula (13) are as follows:
for the pipeline along-path head loss, there are:
in the formula (15), lambda is the along-path head loss coefficient; d is the diameter of the water conduit; subscript of Y Indicating the head loss along the course,
the ratio of the two formulas of the formula (15) is adjusted, and the following are:
in order to keep the working conditions of the prototype hydropower station and the model hydropower station similar in the dynamic process, the along-path head loss in the diversion system should be kept consistent with the water turbine head scale, and the combined type (8), the formula (11) and the formula (16) are as follows:
according to the Xie Cai-Manning formula, the transformation is as follows:
in the formula (18), n c Is the roughness of the pipeline; r is the hydraulic radius of the pipeline, and the two formulas of the formula (18) are subjected to ratio and arrangement, so that the method comprises the following steps:
in the dynamic process of the water turbine, the rotation speed change must satisfy the following equation of motion:
in the formula (20), GD 2 Is the moment of a flywheel of the unit,
the ratio of the two formulas of the formula (20) is adjusted, and the following are:
the combination of formula (11) and formula (21) includes:
the turbine output must satisfy the following expression:
the combination of formula (11) and formula (23) includes:
the expression of the water hammer constructive is:
in the formula (25), a is the water hammer wave speed,
to ensure that the model hydropower station is similar to the prototype hydropower station in the dynamic process, the ratio of the water hammer to the time is kept consistent, and the method comprises the following steps:
from this, a similarity criterion of the model hydropower station and the prototype hydropower station is obtained, and the expression is:
3. the semi-physical simulation model test method for the hydropower station transient process according to claim 1, wherein in the step 2, the framework of the semi-physical simulation model for the hydropower station transient process comprises a high-pressure tank (1), a first pressure-making tank (3), a computer (5), a second pressure-making tank (7), a vacuum tank (9) and a hydropower set (13), wherein the high-pressure tank (1) is internally filled with high-pressure air, a part of water and a part of air are filled in the first pressure-making tank (3), the top of the first pressure-making tank (3) is simultaneously communicated with a first electromagnetic valve (2) and a second electromagnetic valve (4), the other end of the first electromagnetic valve (2) is communicated with the high-pressure tank (1), and the other end of the second electromagnetic valve (4) is connected with the atmosphere or the vacuum tank (9); one way of the bottom of the first pressure generating tank (3) is connected with the outlet of the water pump (11) through a pipeline, the inlet of the water pump (11) is provided with the first check valve (10), the other way of the bottom of the first pressure generating tank (3) is connected with the volute inlet of the hydraulic power unit (13), and the tail water pipe end of the hydraulic power unit (13) is connected with the bottom of the second pressure generating tank (7); the second pressure making tank (7) is also filled with part of water and part of air, the bottom of the second pressure making tank (7) is additionally provided with a second check valve (15), the top of the second pressure making tank (7) is simultaneously communicated with a third electromagnetic valve (6) and a fourth electromagnetic valve (8), the other end of the third electromagnetic valve (6) is connected with the atmosphere or the high-pressure tank (1), and the other end of the fourth electromagnetic valve (8) is communicated with the vacuum tank (9); a first measuring device (12) is arranged at the inlet end of the volute of the hydraulic power unit (13), and a second measuring device (14) is arranged at the outlet end of the draft tube of the hydraulic power unit (13); the first measuring device (12) and the second measuring device (14) are simultaneously connected with the signal input end of the computer (5), and the signal output end of the computer (5) is simultaneously connected with the first electromagnetic valve (2), the second electromagnetic valve (4), the third electromagnetic valve (6) and the fourth electromagnetic valve (80).
4. A semi-physical simulation model test method for hydropower station transient according to claim 3, characterized in that a mathematical model of a diversion system is established in a computer (5), wherein the mathematical model comprises, but is not limited to, a mathematical model for solving pipeline water hammer by adopting a characteristic line method, a mathematical model for solving pipeline water hammer by adopting a wave characteristic method, or a mathematical model for solving pipeline water hammer by adopting an analytical function method, the mathematical model comprises all over-current component models from an upstream water reservoir to a water turbine inlet and all over-current component models from a water turbine outlet to a downstream water channel, and the water turbine inlet and the water turbine outlet are boundary conditions of the mathematical model;
the method comprises the steps that real-time water pressure and flow at the inlet of the water turbine are obtained through a first measuring device (12), measured values are transmitted to a computer (5), the computer (5) takes the flow measured by the first measuring device (12) as the boundary between an upstream water reservoir and an overflow part model at the inlet of the water turbine, the real-time water pressure at the inlet of the water turbine is obtained through calculation, and the real-time water pressure is compared with the water pressure measured by the first measuring device (12); when the water pressure measured by the measuring device I (12) is lower than the real-time water pressure obtained by calculation, the computer (5) controls the electromagnetic valve I (2) to be opened and the electromagnetic valve II (4) to be closed, compressed air in the high-pressure tank (1) enters the pressure-making tank I (3), the check valve I (10) is closed, water loss in the pressure-making tank I (3) is prevented, and the water pressure value at the inlet of the water turbine is improved; when the water pressure measured by the first measuring device (12) is higher than the real-time water pressure obtained by calculation, the first electromagnetic valve (2) is controlled by the computer (5) to be closed, the second electromagnetic valve (4) is controlled by the computer (5) to be opened, compressed air in the pressure generating tank (3) is discharged out of the pressure generating tank at the moment, the water pressure value at the inlet of the water turbine is reduced, and the water pressure at the inlet of the water turbine is further guaranteed to be equal to the calculated water pressure of the computer (5) in real time;
meanwhile, the real-time water pressure and the flow at the outlet of the water turbine are obtained through the second measuring device (14), the measured value is transmitted to the computer (5), the computer (5) takes the flow obtained by the second measuring device (14) as the boundary of the model of the flow passing component from the outlet of the water turbine to the downstream river, the real-time water pressure at the outlet of the water turbine is obtained by calculation, and the real-time water pressure is compared with the water pressure obtained by the second measuring device (14); when the measuring device II (14) measures that the obtained water pressure is lower than the calculated real-time water pressure, the computer (5) controls the electromagnetic valve III (6) to be opened and the electromagnetic valve IV (8) to be closed, and at the moment, the atmosphere enters the pressure-making tank II (7) through the electromagnetic valve III (6), so that the water pressure value at the outlet of the water turbine is improved; when the obtained water pressure is higher than the calculated real-time water pressure, the computer (5) controls the electromagnetic valve III (6) to be closed and the electromagnetic valve IV (8) to be opened, air in the pressure making tank II (7) enters the vacuum tank, the check valve II (15) is closed at the moment, tail liquid is prevented from entering the pressure making tank II to cause pressure reduction failure, the water pressure value at the outlet of the water turbine is reduced, and the water pressure at the outlet of the water turbine is further guaranteed to be equal to the calculated water pressure of the computer (5) in real time.
5. The hydropower station transient semi-physical simulation model test method according to claim 1, wherein in step 3, the specific process is:
3.1 Solving the key parameters of the model hydropower station,
hydraulic turbine scale x for determining prototype hydropower station and model hydropower station D Water diversion system scale x L Transient time scale x t Calculating the length L of each water conduit of the model hydropower station according to the related parameters of the prototype hydropower station (27) 2 Diameter d of each water diversion pipeline of model hydropower station 2 Local head loss coefficient xi of each place in model hydropower station water diversion system 2 Roughness n of each section of pipeline in model hydropower station water diversion system c2 Water hammer wave speed a of pipelines of water diversion system of model hydropower station 2 Nominal diameter D of model hydropower station hydroturbine 2 Model hydropower station head H 2 Model hydropower station unit flow Q 2 Model hydropower station unit rotating speed n 2 Model hydropower station unit torque M 2 Unit flywheel moment of model hydropower station
Model hydropower station hydroturbine output P 2 ；
3.2 A related parameter of the test stand is set,
determining model hydroelectric power plant unit data of a test bed, including the nominal diameter D of a water turbine of the model hydroelectric power plant 2 Water head H of model hydropower station 2 Unit flow Q of model hydropower station 2 Unit rotation speed n of model hydropower station 2 Unit torque M of model hydropower station 2 Unit flywheel moment of model hydropower station
Model hydropower station hydroturbine output P 2 ；
Setting related parameters of a model hydropower station water diversion system in a computer 5, wherein the related parameters comprise the length L of each water diversion pipeline of the model hydropower station 2 Diameter d of each water diversion pipeline of model hydropower station 2 Local head loss coefficient xi of each place in model hydropower station water diversion system 2 Roughness n of each section of pipeline in model hydropower station water diversion system c2 Water hammer wave speed a of pipelines of water diversion system of model hydropower station 2 ；
3.3 A transition process test of the model hydropower station is carried out,
according to the transient process time scale x of the model hydropower station t And calculating the guide vane movement rule of the model hydropower station, measuring the rotating speed of the model hydropower station unit, the water pressure of the volute, the water pressure of the draft tube and the flow state change process in the water turbine by applying similar disturbance in the model hydropower station, and reversely calculating the change process of the relevant parameters of the prototype hydropower station according to a formula (27).
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| CN117034527B (en) * | 2023-09-22 | 2024-03-19 | 水利部交通运输部国家能源局南京水利科学研究院 | Similar design method for local variable scale resistance of global river network physical model |
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