A method and system for calculating the inflow of a run-of-river hydropower station.

Abstract

The present invention provides a method and system for calculating the inflow of a run-of-river hydropower station. The method calculates the power generation reference flow of the power station by obtaining the water level of the pressure forebay and the output status of each unit. At the same time, the flow deviation value is calculated according to the layout of the water diversion system, thereby obtaining the inflow of the hydropower station. The calculation method can better realize the calculation of the inflow of the power station based on the operating performance of the power station.

Description

Technical Field

[0001] The invention relates to water conservancy projects, and in particular to a method and system for calculating the inflow of a run-of-river hydropower station. Background Art

[0002] Run-of-river hydropower stations are a common form of hydropower station structure in my country. They directly use natural runoff or channel flow to generate electricity. This type of hydropower station does not have the ability to regulate the incoming flow. Therefore, the water flow rate used for power generation needs to match the actual incoming flow of the power station. However, due to the uncertainty of the amount of water used by the unit, it is often difficult to determine a reasonable startup plan to adapt to the matching of the incoming flow in the actual process.

[0003] For the operation of run-of-river hydropower stations, it is particularly important to determine a reasonable startup and operation plan, which requires determining a reasonable inflow according to the startup and operation status. How to determine the inflow of a run-of-river hydropower station based on the current status of the unit and the change in the water level in the forebay is of great significance to the operation of the power station. Summary of the invention

[0004] Based on the above technical problems, the present invention provides a method and system for calculating the inflow of a run-of-river hydropower station.

[0005] A method for calculating the flow rate of a run-of-river hydropower station, the run-of-river hydropower station comprises a water diversion channel, a pressure forebay, a pressure pipeline, a hydro-turbine generator set and a tailwater system, the water diversion channel is a rectangular channel, the bottom width of which is b, the water diversion channel is connected to the pressure forebay, the pressure pipeline is connected to the pressure forebay, the pressure pipeline is connected to the hydro-turbine generator set, the hydro-turbine generator set is connected to the tailwater system, the hydro-turbine generator set is configured as n units, n is an integer greater than or equal to 1, a water level measuring device is installed on the pressure forebay, and an output collection device is installed on the hydro-turbine generator set, and the method for calculating the flow rate is as follows:

[0006] S1: Obtain the change in the water level of the pressure forebay in the time period T, assuming that the water level of the pressure forebay at the beginning of the time period is Hs1, and the water level at the end of the time period is Hs2;

[0007] S2: According to the forebay water levels Hs1 and Hs2 measured by the water level measuring device on the pressure forebay, the forebay water level used for calculation in this step is determined to be Hs3, Hs3 is the average value of Hs1 and Hs2, and the power generation flow of each unit is calculated in combination with the output of each unit collected by the output collection device installed on the hydro-generator unit, and the power generation reference flow of the power station at this time is obtained, and the power generation reference flow is equal to the sum of the power generation flow of each unit;

[0008] S3: Find the water level-area curve of the pressure forebay, and find the area A1 corresponding to Hs1 and the area A2 corresponding to Hs2;

[0009] S4: Determine the water flow velocity v in the water diversion channel according to the power generation reference flow rate and the bottom width and bottom slope of the water diversion channel;

[0010] S5: Calculate the change in water volume in the pressure forebay and channel during the T period, the change in water volume V = (A1 / 2 + A2 / 2 + v × T × b) × (Hs2-Hs1); when Hs1 is less than Hs2, V is a positive value, and when Hs1 is greater than Hs2, V is a negative value;

[0011] S6: The deviation value between the power station's referenced flow and the incoming flow is V / T; the incoming flow of the power station is equal to the sum of the referenced flow and the deviation value. When Hs1 is less than Hs2, the deviation value is positive, and when Hs1 is greater than Hs2, the deviation value is negative.

[0012] Preferably, the power generation flow rate of each unit calculated in S2 needs to be obtained based on the comprehensive characteristic curve or operation characteristic curve of the turbine and the tailwater flow curve.

[0013] Preferably, the water level-area curve of the pressure forepool can obtain the area corresponding to the pressure forepool according to any water level of the pressure forepool.

[0014] Preferably, the water diversion channel is a channel with a regular cross-section.

[0015] Preferably, the short time T is 3 minutes or 5 minutes.

[0016] A system that applies the above-mentioned method for calculating the flow rate of a run-of-river hydropower station is characterized in that: the system includes a power generation reference flow calculation module and a deviation value calculation module, the power generation reference flow calculation module is used to calculate the power generation reference flow of the power station according to the water level of the pressure forebay and the output of each unit, and the deviation value calculation module is used to calculate the deviation value according to the change of the forebay water level and the power generation reference flow.

[0017] Preferably, the system further comprises an incoming flow calculation module, and the incoming flow calculation module is used to calculate the incoming flow of the power station according to the power generation reference flow and the deviation value.

[0018] The present invention sets a water level gauge in the forebay of the hydropower station to reflect the change of the water level in the forebay. The forebay water level gauge is used in combination with the unit output to reflect the water consumption of the unit. The change of the water level in the forebay reflects the change of the water capacity of the forebay. In addition, the influence of the end of the channel and the actual water consumption of the unit are superimposed, so as to more accurately reflect the actual water inflow situation of the power station.

[0019] Beneficial effects:

[0020] The present invention provides a method and system for calculating the inflow of a run-of-river hydropower station. The method calculates the power generation reference flow of the power station by obtaining the water level of the pressure forebay and the output status of each unit. At the same time, the flow deviation value is calculated according to the layout of the water diversion system, thereby obtaining the inflow of the hydropower station. The calculation method can better realize the calculation of the inflow of the power station based on the operating performance of the power station. DETAILED DESCRIPTION

[0021] The present invention provides a method for calculating the flow rate of a runoff hydropower station. The runoff hydropower station comprises a water diversion channel, a pressure forebay, a pressure pipeline, a hydro-turbine generator set and a tailwater system. The water diversion channel is a rectangular channel with a bottom width of b. The water diversion channel is connected to the pressure forebay, the pressure pipeline is connected to the pressure forebay, the pressure pipeline is connected to the hydro-turbine generator set, the hydro-turbine generator set is connected to the tailwater system, the hydro-turbine generator set is configured as n units, n is an integer greater than or equal to 1, a water level measuring device is installed on the pressure forebay, and an output collecting device is installed on the hydro-turbine generator set. The method for calculating the flow rate is as follows:

[0022] S1: Obtain the change in the water level of the pressure forebay in the time period T, assuming that the water level of the pressure forebay at the beginning of the time period is Hs1, and the water level at the end of the time period is Hs2;

[0023] S2: According to the forebay water levels Hs1 and Hs2 measured by the water level measuring device on the pressure forebay, the forebay water level used for calculation in this step is determined to be Hs3, Hs3 is the average value of Hs1 and Hs2, and the power generation flow of each unit is calculated in combination with the output of each unit collected by the output collection device installed on the hydro-generator unit, and the power generation reference flow of the power station at this time is obtained, and the power generation reference flow is equal to the sum of the power generation flow of each unit;

[0024] S3: Find the water level-area curve of the pressure forebay, and find the area A1 corresponding to Hs1 and the area A2 corresponding to Hs2;

[0025] S4: Determine the water flow velocity v in the water diversion channel according to the power generation reference flow rate and the bottom width and bottom slope of the water diversion channel;

[0026] As a specific implementation method, the water flow velocity in the channel can be calculated using the formula for uniform flow in an open channel;

[0027] S5: Calculate the change in water volume in the pressure forebay and channel during the T period, the change in water volume V = (A1 / 2 + A2 / 2 + v × T × b) × (Hs2-Hs1); when Hs1 is less than Hs2, V is a positive value, and when Hs1 is greater than Hs2, V is a negative value;

[0028] S6: The deviation value between the power station's referenced flow and the incoming flow is V / T; the incoming flow of the power station is equal to the sum of the referenced flow and the deviation value. When Hs1 is less than Hs2, the deviation value is positive, and when Hs1 is greater than Hs2, the deviation value is negative.

[0029] Preferably, the power generation flow rate of each unit calculated in S2 needs to be obtained based on the comprehensive characteristic curve or operation characteristic curve of the turbine and the tailwater flow curve.

[0030] Preferably, the water level-area curve of the pressure forepool can obtain the area corresponding to the pressure forepool according to any water level of the pressure forepool.

[0031] Preferably, the water diversion channel is a channel with a regular cross-section.

[0032] Preferably, the time period T is 3 minutes or 5 minutes.

[0033] A system that applies the above-mentioned method for calculating the flow rate of a run-of-river hydropower station is characterized in that: the system includes a power generation reference flow calculation module and a deviation value calculation module, the power generation reference flow calculation module is used to calculate the power generation reference flow of the power station according to the water level of the pressure forebay and the output of each unit, and the deviation value calculation module is used to calculate the deviation value according to the change of the forebay water level and the power generation reference flow.

[0034] Preferably, the system further comprises an incoming flow calculation module, and the incoming flow calculation module is used to calculate the incoming flow of the power station according to the power generation reference flow and the deviation value.

[0035] The forebay water level and the output computer group reference flow rate need to be calculated in combination with the tailwater flow curve, the unit operation efficiency curve, etc., and the exhaustive method can also be used to calculate, exhaustively enumerate the possible flow combinations, and find the flow distribution that meets the current working conditions;

[0036] The flow velocity of the water diversion channel is calculated by adopting the open channel hydraulic calculation method, taking into account the bottom width, bottom slope, roughness, etc. of the channel to calculate its flow velocity, which is proportional to the flow rate.

[0037] The principle logic of this method is that there is a deviation between the incoming flow and the power generation flow. If the water level in the forebay rises, it means that the incoming flow is greater than the power generation flow of the unit. Then, the water increase value caused by the rising water level in the forebay during the time period is calculated. In addition to affecting the volume of the pressure forebay, this water increase value also affects a part of the end of the channel. The part of the end of the channel can be obtained by multiplying the channel flow velocity by the time period to get the affected distance. This processing method can more accurately reflect the current power station's incoming flow relationship. If the pressure forebay rises faster, it means that the incoming flow is larger. Conversely, if the water level in the pressure forebay drops, it means that the incoming flow is less than the power station's reference flow. At this time, the power station's reference flow should be reduced, such as reducing the load.

[0038] The reference flow rate of the unit can be calculated according to the output of each unit and the water level of the forebay. The specific method is: for each unit, assuming that its flow rate is x, then the total startup flow rate of all units is the sum of the x of each unit. According to the total startup flow rate, the tailwater flow curve of the power station is found to obtain the tailwater level. According to the x of each unit and the unit layout, the head loss of each unit is calculated to obtain the net power head of each unit. According to the net power head and flow of each unit, the characteristic curve of the turbine is found to obtain its efficiency, and then its power value is obtained. The obtained power value is compared with the collected output value, and the x of each unit is continuously corrected until the calculated power value matches the collected output value. This trial calculation process can be implemented by computer programming.

[0039] The above-mentioned embodiments are only preferred embodiments of the present invention. The protection scope of the present invention should not be regarded as limited to the specific forms described in the embodiments. The protection scope of the present invention also includes equivalent technical means that can be thought of by those skilled in the art based on the concept of the present invention.

Claims

1. A method for calculating the flow rate of a runoff hydropower station, the runoff hydropower station comprises a water diversion channel, a pressure forebay, a pressure pipeline, a hydro-turbine generator set and a tailwater system, the water diversion channel is a rectangular channel, the bottom width of which is b, the water diversion channel is connected to the pressure forebay, the pressure pipeline is connected to the pressure forebay, the pressure pipeline is connected to the hydro-turbine generator set, the hydro-turbine generator set is connected to the tailwater system, the hydro-turbine generator set is configured as n units, n is an integer greater than or equal to 1, a water level measuring device is installed on the pressure forebay, and an output collection device is installed on the hydro-turbine generator set, and the method for calculating the flow rate is as follows: S1: Obtain the change in the water level of the pressure forebay in the time period T, assuming that the water level of the pressure forebay at the beginning of the time period is Hs1, and the water level at the end of the time period is Hs2; S2: According to the forebay water levels Hs1 and Hs2 measured by the water level measuring device on the pressure forebay, the forebay water level used for calculation in this step is determined to be Hs3, Hs3 is the average value of Hs1 and Hs2, and the power generation flow of each unit is calculated in combination with the output of each unit collected by the output collection device installed on the hydro-generator unit, and the power generation reference flow of the power station at this time is obtained, and the power generation reference flow is equal to the sum of the power generation flow of each unit; S3: Find the water level-area curve of the pressure forebay, and find the area A1 corresponding to Hs1 and the area A2 corresponding to Hs2; S4: Determine the water flow velocity v in the water diversion channel according to the power generation reference flow rate and the bottom width and bottom slope of the water diversion channel; S5: Calculate the change in water volume in the pressure forebay and channel during the T period, the change in water volume V = (A1 / 2 + A2 / 2 + v × T × b) × (Hs2-Hs1); when Hs1 is less than Hs2, V is a positive value, and when Hs1 is greater than Hs2, V is a negative value; S6: The deviation value between the power station's referenced flow and the incoming flow is V / T; the incoming flow of the power station is equal to the sum of the referenced flow and the deviation value. When Hs1 is less than Hs2, the deviation value is positive, and when Hs1 is greater than Hs2, the deviation value is negative.

2. The method for calculating the flow rate of a run-of-river hydropower station according to claim 1, characterized in that: The calculation of the power generation flow of each unit in S2 needs to be obtained based on the comprehensive characteristic curve or operation characteristic curve of the hydro-generator set and the tailwater flow curve.

3. The method for calculating the flow rate of a run-of-river hydropower station according to claim 1, characterized in that: The water level-area curve of the pressure forepool is used to obtain the area corresponding to the pressure forepool according to any water level of the pressure forepool.

4. The method for calculating the flow rate of a run-of-river hydropower station according to claim 1, characterized in that: The water diversion channel is a channel with a regular cross section.

5. The method for calculating the flow rate of a run-of-river hydropower station according to claim 1, characterized in that: The time period T is 3 minutes or 5 minutes.

6. A system using the method for calculating the flow rate of a run-of-river hydropower station as claimed in any one of claims 1 to 5, characterized in that: The system includes a power generation reference flow calculation module and a deviation value calculation module. The power generation reference flow calculation module is used to calculate the power generation reference flow of the power station according to the water level of the pressure forebay and the output of each unit. The deviation value calculation module is used to calculate the deviation value according to the water level change of the forebay and the power generation reference flow.

7. The system for calculating the flow rate of a run-of-river hydropower station according to claim 6, characterized in that: The system further comprises an incoming flow calculation module, which is used to calculate the incoming flow of the power station according to the power generation reference flow and the deviation value.