A method and system for optimizing operation of cascade hydropower stations under constant load

Abstract

The present invention provides an adjustment method for the fixed-load operation of a cascade hydropower station, which fully considers the hydraulic relationship of the cascade hydropower station, provides a load operation mode of the cascade hydropower station on the basis of considering the optimized operation within the hydropower station, and provides a load adjustment method for load deviations that occur after stable operation, thereby realizing the startup and adjustment operation mode of the cascade hydropower station units under a given load.

Description

Technical Field

[0001] The invention relates to an optimized operation mode of a hydropower station, and in particular to a constant load optimized operation method and system of a cascade hydropower station. Background Art

[0002] A cascade hydropower station refers to a hydropower station that forms a cascade relationship in terms of hydraulic relations. It generally includes an upstream leading reservoir and a downstream runoff hydropower station. The tailwater of the reservoir power station is connected in sequence to the downstream runoff hydropower station, that is, there is a definite hydraulic relationship among the cascade hydropower stations; the power generation tailwater of the reservoir power station is connected in sequence to the downstream runoff hydropower station, that is, when the loss of the water diversion channel is not considered, the power generation flow of the reservoir power station is equal to the power generation flow of the downstream runoff hydropower station. This type of cascade hydropower station can make better use of hydraulic energy.

[0003] When cascade hydropower stations are operating at a fixed load, they often need to execute the load value given by the power grid system. For reservoir power stations, as long as the given load is less than the maximum output under the current reservoir water level, the unit can be accurately opened to the given load. However, for run-of-river hydropower stations, since their water inflow has been determined (that is, the upstream reservoir power station determines the corresponding power generation flow under the load), their load is determined according to the water inflow at this time, and the load cannot be adjusted. When distributing the load of cascade hydropower stations, after the unit loads of the given reservoir power station and cascade hydropower station are determined, since the water inflow of the run-of-river hydropower station has been determined, it may not be able to generate the given load, or it may exceed the given load, resulting in a deviation between the initial load distribution of the cascade hydropower station and the actual load of the cascade hydropower station after stable operation. Therefore, when distributing the fixed load operation of the cascade hydropower station, it is necessary to formulate a reasonable and scientific distribution model, and make reasonable adjustments to the deviations that occur after stable operation. Summary of the invention

[0004] Based on the above technical problems, the present invention provides a method and system for optimizing the operation of a cascade hydropower station at a constant load.

[0005] A method for optimizing the operation of a cascade hydropower station at a constant load, wherein the cascade hydropower station includes an upstream reservoir power station and a downstream runoff hydropower station, wherein there is one reservoir power station and n runoff hydropower stations, and the runoff hydropower stations all include a pressure forebay, and the tailwater of the reservoir power station is sequentially connected to the downstream runoff hydropower station, that is, the cascade hydropower stations have a certain hydraulic relationship, and the constant load operation is that the cascade hydropower station performs a given load operation, and the adjustment method comprises the following steps:

[0006] S1: Monitor the reservoir water level of the upstream reservoir power station, and optimize the in-plant operation of the reservoir power station and the downstream run-of-river hydropower station in the order of flow rate from small to large, find the optimal load of the reservoir power station and the downstream run-of-river hydropower station corresponding to each flow rate, and accumulate the optimal load of the reservoir power station and the downstream run-of-river hydropower station to find the optimal load of the cascade hydropower station corresponding to each flow rate under the current reservoir water level, thereby forming the flow-optimal load library of the cascade hydropower station under the current water level;

[0007] S2: According to the given load, find the flow rate of the cascade hydropower station under the current water level obtained in S1 - the optimal load reservoir, find the flow rate corresponding to the given load, and according to the flow rate and the current reservoir water level, perform the in-plant optimization operation of the reservoir power station and the downstream run-of-river hydropower station respectively, and obtain the unit load distribution of the reservoir power station and the downstream run-of-river hydropower station;

[0008] S3: Start the reservoir power station and the downstream run-of-river hydropower station according to the load distribution of the units obtained in S2. After the downstream run-of-river hydropower station is started and operated stably, observe the water level of the pressure forepool. When the water level of the pressure forepool drops, reduce the load to operate at a stable high water level of the pressure forepool; when the water level of the pressure forepool rises, increase the load to operate at a stable high water level of the pressure forepool; after the downstream run-of-river hydropower station is operating stably, collect the total load of the cascade hydropower station;

[0009] S4: Compare the total load of the collected cascade hydropower station with the given load, and calculate the load difference ΔN; when the load difference ΔN is less than the set value, complete the fixed load distribution, and the cascade hydropower station operates in the existing manner; when the load difference ΔN is greater than the set value, execute step S5;

[0010] S5: Collect the reservoir water level, the pressure forebay water level of the downstream run-of-river hydropower station, and the tailwater level of the reservoir power station and the downstream run-of-river hydropower station, and calculate the gross heads of the reservoir power station and the downstream run-of-river hydropower station respectively based on the reservoir water level, the pressure forebay water level, and the tailwater level, which are H(1), H(2)…H(n+1) respectively; distribute the load difference according to the proportion of the gross head, wherein the total load of the reservoir power station is adjusted to H(1)×ΔN / (H(1)+H(2)+…+H(n+1)), and the downstream run-of-river hydropower station adjusts the power station load in turn according to the adjustment method;

[0011] S6: According to the load adjustment in S5, load adjustment is performed for each level of the cascade hydropower station, and step S4 is executed.

[0012] Preferably, the in-plant optimization operation of the reservoir power station is as follows: for any discharge flow, the in-plant units are allocated according to the current reservoir water level, and the group with the largest unit output corresponding to the unit allocation flow is calculated as the optimal load corresponding to the current discharge flow.

[0013] Preferably, the optimized operation within the run-of-river power station is as follows: for any discharge flow, the units within the plant are allocated according to the high water level of the pressure forebay designed for the run-of-river hydropower station, and the group with the largest unit output corresponding to the unit allocation flow is calculated as the optimal load corresponding to the current discharge flow.

[0014] Preferably, the tailwater level of the reservoir power station or the downstream run-of-river hydropower station can be calculated based on a tailwater flow curve, that is, any discharge flow corresponds to a determined tailwater level.

[0015] Preferably, the reservoir hydropower station and the downstream run-of-river hydropower station can both calculate the optimal unit load distribution and the maximum output of the power station corresponding to any flow rate.

[0016] Preferably, the set value in S4 is plus or minus 10% of the given load, and the load difference ΔN being less than the set value is represented as follows: the load difference is greater than minus 10% of the given load and less than plus 10% of the given load.

[0017] Preferably, the set value in S4 is plus or minus 5% of the given load, and the load difference ΔN being less than the set value is represented by: the load difference being greater than minus 5% of the given load and less than plus 5% of the given load.

[0018] A system for executing the above-mentioned method for optimizing the operation of cascade hydropower stations at a constant load, the optimization system comprising a data acquisition module, a load distribution module and a load adjustment module, the data acquisition module can collect the water level of the reservoir, the water level of the pressure forebay of the downstream run-of-river hydropower station, the tailwater level of the reservoir power station and the downstream run-of-river hydropower station, and the output of the cascade hydropower station; the load distribution module is used to calculate the initial load distribution of each unit of the cascade hydropower station according to a given load and the current reservoir water level; the load adjustment module is used to adjust the load of the cascade hydropower station according to the collected data after the initial load distribution and the stable operation of the run-of-river hydropower station.

[0019] Beneficial effect: The present invention provides an adjustment method for fixed-load operation of a cascade hydropower station, which fully considers the hydraulic relationship of the cascade hydropower station, provides a load operation mode of the cascade hydropower station on the basis of considering the optimized operation within the hydropower station, and provides a load adjustment method for load deviations that occur after stable operation, thereby realizing the startup and adjustment operation mode of the cascade hydropower station units under a given load. DETAILED DESCRIPTION

[0020] The present invention provides a method for optimizing the operation of a cascade hydropower station under a fixed load. The cascade hydropower station includes an upstream reservoir power station and a downstream runoff hydropower station, wherein there is one reservoir power station and n runoff hydropower stations, and the runoff hydropower stations all include a pressure forebay. The tail water of the reservoir power station is sequentially connected to the downstream runoff hydropower station, that is, the cascade hydropower station has a certain hydraulic relationship. The fixed load operation is that the cascade hydropower station performs a given load operation. The adjustment method includes the following steps:

[0021] S1: Monitor the reservoir water level of the upstream reservoir power station, and optimize the in-plant operation of the reservoir power station and the downstream run-of-river hydropower station in the order of flow rate from small to large, find the optimal load of the reservoir power station and the downstream run-of-river hydropower station corresponding to each flow rate, and accumulate the optimal load of the reservoir power station and the downstream run-of-river hydropower station to find the optimal load of the cascade hydropower station corresponding to each flow rate under the current reservoir water level, thereby forming the flow-optimal load library of the cascade hydropower station under the current water level;

[0022] S2: According to the given load, find the flow rate of the cascade hydropower station under the current water level obtained in S1 - the optimal load reservoir, find the flow rate corresponding to the given load, and according to the flow rate and the current reservoir water level, perform the in-plant optimization operation of the reservoir power station and the downstream run-of-river hydropower station respectively, and obtain the unit load distribution of the reservoir power station and the downstream run-of-river hydropower station;

[0023] S3: Start the reservoir power station and the downstream run-of-river hydropower station according to the load distribution of the units obtained in S2. After the downstream run-of-river hydropower station is started and operated stably, observe the water level of the pressure forepool. When the water level of the pressure forepool drops, reduce the load to operate at a stable high water level of the pressure forepool; when the water level of the pressure forepool rises, increase the load to operate at a stable high water level of the pressure forepool; after the downstream run-of-river hydropower station is operating stably, collect the total load of the cascade hydropower station;

[0024] S4: Compare the total load of the collected cascade hydropower station with the given load, and calculate the load difference ΔN; when the load difference ΔN is less than the set value, complete the fixed load distribution, and the cascade hydropower station operates in the existing manner; when the load difference ΔN is greater than the set value, execute step S5;

[0025] S5: Collect the reservoir water level, the pressure forebay water level of the downstream run-of-river hydropower station, and the tailwater level of the reservoir power station and the downstream run-of-river hydropower station, and calculate the gross heads of the reservoir power station and the downstream run-of-river hydropower station respectively based on the reservoir water level, the pressure forebay water level, and the tailwater level, which are H(1), H(2)…H(n+1) respectively; distribute the load difference according to the proportion of the gross head, wherein the total load of the reservoir power station is adjusted to H(1)×ΔN / (H(1)+H(2)+…+H(n+1)), and the downstream run-of-river hydropower station adjusts the power station load in turn according to the adjustment method;

[0026] S6: According to the load adjustment in S5, load adjustment is performed for each level of the cascade hydropower station, and step S4 is executed.

[0027] Preferably, the in-plant optimization operation of the reservoir power station is as follows: for any discharge flow, the in-plant units are allocated according to the current reservoir water level, and the group with the largest unit output corresponding to the unit allocation flow is calculated as the optimal load corresponding to the current discharge flow.

[0028] Preferably, the optimized operation within the run-of-river power station is as follows: for any discharge flow, the units within the plant are allocated according to the high water level of the pressure forebay designed for the run-of-river hydropower station, and the group with the largest unit output corresponding to the unit allocation flow is calculated as the optimal load corresponding to the current discharge flow.

[0029] Preferably, the tailwater level of the reservoir power station or the downstream run-of-river hydropower station can be calculated based on a tailwater flow curve, that is, any discharge flow corresponds to a determined tailwater level.

[0030] Preferably, the reservoir hydropower station and the downstream run-of-river hydropower station can both calculate the optimal unit load distribution and the maximum output of the power station corresponding to any flow rate.

[0031] Preferably, the set value in S4 is plus or minus 10% of the given load, and the load difference ΔN being less than the set value is represented as follows: the load difference is greater than minus 10% of the given load and less than plus 10% of the given load.

[0032] Preferably, the set value in S4 is plus or minus 5% of the given load, and the load difference ΔN being less than the set value is represented by: the load difference being greater than minus 5% of the given load and less than plus 5% of the given load.

[0033] A system for executing the above-mentioned method for optimizing the operation of cascade hydropower stations at a constant load, the optimization system comprising a data acquisition module, a load distribution module and a load adjustment module, the data acquisition module can collect the water level of the reservoir, the water level of the pressure forebay of the downstream run-of-river hydropower station, the tailwater level of the reservoir power station and the downstream run-of-river hydropower station, and the output of the cascade hydropower station; the load distribution module is used to calculate the initial load distribution of each unit of the cascade hydropower station according to a given load and the current reservoir water level; the load adjustment module is used to adjust the load of the cascade hydropower station according to the collected data after the initial load distribution and the stable operation of the run-of-river hydropower station.

[0034] 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 optimizing the operation of a cascade hydropower station at a constant load, wherein the cascade hydropower station comprises an upstream reservoir power station and a downstream run-of-river hydropower station, wherein there is one reservoir power station and n run-of-river hydropower stations, and each of the run-of-river hydropower stations comprises a pressure forebay, and the tailwater of the reservoir power station is sequentially connected to the downstream run-of-river hydropower station, that is, the cascade hydropower station has a certain hydraulic relationship, and the constant load operation is that the cascade hydropower station performs a given load operation, and the method comprises the following steps: S1: Monitor the reservoir water level of the upstream reservoir power station, and optimize the in-plant operation of the reservoir power station and the downstream run-of-river hydropower station in the order of flow rate from small to large, find the optimal load of the reservoir power station and the downstream run-of-river hydropower station corresponding to each flow rate, and accumulate the optimal load of the reservoir power station and the downstream run-of-river hydropower station to find the optimal load of the cascade hydropower station corresponding to each flow rate under the current reservoir water level, thereby forming the flow-optimal load library of the cascade hydropower station under the current reservoir water level; S2: According to the given load, find the flow rate under the current reservoir water level of the cascade hydropower station obtained in S1 - the optimal load pool, find the flow rate corresponding to the given load, and according to the flow rate corresponding to the given load and the current reservoir water level, perform the in-plant optimization operation of the reservoir power station and the downstream run-of-river hydropower station respectively, and obtain the unit load distribution of the reservoir power station and the downstream run-of-river hydropower station; S3: Start the reservoir power station and the downstream run-of-river hydropower station according to the load distribution of the units obtained in S2. After the downstream run-of-river hydropower station is started and operated stably, observe the water level of the pressure forepool. When the water level of the pressure forepool drops, reduce the load to operate at a stable high water level of the pressure forepool; when the water level of the pressure forepool rises, increase the load to operate at a stable high water level of the pressure forepool; after the downstream run-of-river hydropower station is operating stably, collect the total load of the cascade hydropower station; S4: Compare the collected total load of the cascade hydropower stations with the given load, and calculate the load difference ΔN; When the load difference ΔN is less than the set value, the fixed load distribution is completed, and the cascade hydropower station operates in the existing manner; when the load difference ΔN is greater than the set value, step S5 is executed; S5: collecting the reservoir water level, the pressure forebay water level of the downstream run-of-river hydropower station, collecting the tailwater levels of the reservoir power station and the downstream run-of-river hydropower station, and calculating the gross heads of the reservoir power station and the downstream run-of-river hydropower station respectively based on the reservoir water level, the pressure forebay water level, and the tailwater level, which are H(1), H(2)…H(n+1) respectively; distributing the load difference according to the proportion of the gross head, wherein the total load of the reservoir power station is adjusted to H(1)×ΔN / (H(1)+H(2)+…+H(n+1)), and the downstream run-of-river hydropower station adjusts the power station load in accordance with the adjustment method of the total load of the reservoir power station; S6: According to the load adjustment in S5, the load of each power station of the cascade hydropower station is adjusted, and step S4 is executed.

2. The method for optimizing operation of a cascade hydropower station at a constant load according to claim 1, characterized in that: The in-plant optimization operation of the reservoir power station is as follows: for any flow rate, the in-plant units are allocated according to the current reservoir water level, and the group with the largest unit output corresponding to the unit allocation flow rate is calculated as the optimal load corresponding to the current flow rate.

3. The method for optimizing operation of a cascade hydropower station at a constant load according to claim 1, characterized in that: The optimal operation within the run-of-river hydropower station is as follows: for any flow rate, the units within the plant are allocated according to the high water level of the pressure forebay designed for the run-of-river hydropower station, and the group with the largest unit output corresponding to the unit allocation flow rate is calculated as the optimal load corresponding to the current flow rate.

4. The method for optimizing operation of a cascade hydropower station at a constant load according to claim 2 or 3, characterized in that: The tailwater level of the reservoir power station or downstream run-of-river hydropower station is calculated based on the tailwater flow curve, that is, any discharge flow corresponds to a determined tailwater level.

5. The method for optimizing operation of a cascade hydropower station at a constant load according to claim 1, characterized in that: The reservoir power station and the downstream run-of-river hydropower station can both calculate the optimal unit load distribution and the maximum output of the power station corresponding to any flow rate.

6. The method for optimizing operation of a cascade hydropower station at a constant load according to claim 1, characterized in that: The set value in S4 is plus or minus 10% of the given load. The load difference ΔN being less than the set value is represented as follows: the load difference is greater than minus 10% of the given load and less than plus 10% of the given load.

7. The method for optimizing operation of a cascade hydropower station at a constant load according to claim 1, characterized in that: The set value in S4 is plus or minus 5% of the given load. The load difference ΔN being less than the set value is represented as follows: the load difference is greater than minus 5% of the given load and less than plus 5% of the given load.

8. A system for executing the fixed-load optimization operation method of a cascade hydropower station as described in any one of claims 1 to 7, the system comprising a data acquisition module, a load distribution module and a load adjustment module, the data acquisition module collecting reservoir water levels, pressure forebay water levels of downstream run-of-river hydropower stations, tailwater levels of reservoir power stations and downstream run-of-river hydropower stations, and output of cascade hydropower stations; the load distribution module is used to calculate the initial load distribution of each unit in the cascade hydropower station according to a given load and the current reservoir water level; the load adjustment module is used to adjust the load of the cascade hydropower station according to the collected data after the initial load distribution and the stable operation of the run-of-river hydropower station.