Method for crossing embargo area through active power distribution of hydroelectric generating set

Abstract

The invention discloses a method for crossing an embargo area through active distribution of a hydroelectric generating set, and the method comprises the steps: obtaining the embargo area of the hydroelectric generating set under different known water heads, and obtaining the embargo area under an unknown water head through an interpolation algorithm; when the active given value of the whole plant is changed, performing active distribution on the unit according to an active distribution principle; when the load of the whole plant cannot meet the scheduling requirement in the current operation area, allowing to cross the embargo area; setting a load imbalance threshold between a crossing embargo zone dead zone and a unit, and obtaining a target unit needing to cross the embargo zone in combination with the direction of the current crossing embargo zone; the method can flexibly adjust the unit load on the premise of ensuring the safety of the unit, enhance the response capability of the hydropower station to the power grid load change, and ensure the stable operation of the power system.

Description

Technical Field

[0001] The invention relates to the technical field of hydropower unit power grid control, and in particular to a method for distributing active power of a hydropower unit across a prohibited area. Background Art

[0002] Usually, the operation area of ​​a turbine is divided into six parts, namely, the cavitation zone, the forbidden zone, the transition zone, the rough operation zone, the vortex zone, the low-frequency oscillation zone, and the stable operation zone. Among them, the cavitation zone, the forbidden zone, the vortex zone, and the low-frequency oscillation zone of the unit are collectively referred to as the forbidden zone of the unit; the transition zone and the rough operation zone of the unit are collectively referred to as the transition operation zone. In order to stabilize the unit, reduce unit wear, and improve the unit operation efficiency, the turbine unit needs to operate in the transition operation zone and the stable operation zone, and try to avoid the forbidden zone. The low-frequency oscillation zone of the unit belongs to the forbidden zone of the unit, and it is necessary to avoid the low-frequency oscillation zone. When the unit enters the low-frequency oscillation zone, it should quickly cross the low-frequency oscillation zone and adjust to the stable operation zone.

[0003] In the prior art, the active power distribution of hydropower units usually follows certain distribution principles, such as the equal incremental rate method, the equal consumption incremental rate method, etc., to ensure the reasonable distribution of the plant load and the economic operation of the units. However, when faced with changes in the plant load demand, especially when the plant load cannot meet the dispatching requirements in the current operating area, the units are usually strictly restricted to operate outside the restricted area. Once the plant load demand changes and it is necessary to cross the restricted area, the system may not be able to make adjustments in time, resulting in unreasonable load distribution or even failure to meet the dispatching requirements. The prior art lacks sufficient flexibility in dealing with the restricted area issue. When the plant load demand changes slightly, even if the risk of crossing the restricted area is small, the system may refuse to adjust due to strict compliance with the restricted area restrictions, resulting in uneven load distribution between units and affecting the overall operating efficiency.

[0004] In addition, when distributing active power, the existing technology often only considers basic factors such as load demand and unit capacity, but ignores the economy and operating status of the unit. This may lead to the selection of uneconomical units or units with poor operating conditions when crossing the restricted area, increasing operating costs and risks. Faced with complex load changes and multiple constraints, the existing technology lacks an intelligent judgment mechanism to accurately determine when and how to cross the restricted area and which unit to select for the crossing operation.

[0005] Therefore, a more flexible and intelligent method for distributing active power of hydropower units is needed to overcome the shortcomings of the existing technology and ensure that the hydropower units can achieve safe, economical and efficient operation while meeting the scheduling requirements. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a method for distributing active power of a hydropower unit across a prohibited zone, which adopts the following technical scheme:

[0007] A method for distributing active power of a hydropower unit across a prohibited zone, the method comprising:

[0008] Step 1: Obtain the prohibited areas of the hydropower station units under different known water heads, and obtain the prohibited areas under unknown water heads through interpolation algorithm.

[0009] Step 2: When the active power given value of the whole plant changes, the active power of the units is distributed according to the active power distribution principle.

[0010] Step 3: When the plant load cannot meet the dispatching requirements in the current operating area, crossing the restricted area is allowed.

[0011] Step 4, setting the dead zone for crossing the forbidden zone and the load imbalance threshold between units, and obtaining the target unit that needs to cross the forbidden zone in combination with the current direction of crossing the forbidden zone.

[0012] Furthermore, the prohibited areas under various working conditions are obtained through interpolation algorithms, including:

[0013] When the number of prohibited areas under the two adjacent water heads is the same, the number of prohibited areas under the current water head is consistent with that under the adjacent water heads:

[0014]

[0015] Among them, P 禁运,i is the power of the ith restricted area under the current water head, P 禁运,i,前 and P 禁运,i,后 are the power of the ith restricted area under the front and rear water heads, H is the current water head, and H 前 and H 后 They are the front and rear water heads respectively.

[0016] When the number of restricted areas under the two adjacent water heads is different, the number of restricted areas under the front and rear water heads is set to be n, and the number of restricted areas under the front and rear water heads is set to be m; if the current water head is close to the water head with fewer restricted areas between the front and rear water heads, the number of restricted areas under the current water head is n, otherwise it is m:

[0017]

[0018] Among them, when i≤n, the power of the restricted area of ​​the previous water head is used for interpolation. When m≥i>n, the power P of the i-th restricted area under the water head with more restricted areas before and after the water head is directly used. 禁运,i,多 .

[0019] Furthermore, the active power allocation principle includes:

[0020] The active power regulation step of the unit is predefined. When the active power set value of the whole plant changes, it is determined whether the change is an increase in load or a decrease in active power.

[0021] If the load is increased, the unit with the smallest active power distribution value last time will be selected; if the increase is within the adjustment step range and does not enter the prohibited area and does not exceed the active power upper limit, only one unit needs to be allocated to complete the adjustment; otherwise, the remaining load will be allocated to the unit with the second smallest active power distribution value last time, and the same judgment will be made until the active power increase is allocated.

[0022] If active power is reduced, the unit with the largest active power distribution value last time will be selected; if the reduction is within the adjustment step range and does not enter the prohibited area and does not exceed the active power upper limit, only one unit needs to be allocated to complete the adjustment; otherwise, the remaining load will be allocated to the unit with the second largest active power distribution value last time, and the same judgment will be made until the active power reduction is allocated.

[0023] Furthermore, the scheduling requirements include: when the power shortage caused by the unit not crossing the restricted area is greater than the power shortage caused by crossing the restricted area, or when the load between units is seriously unbalanced, resulting in the active power difference between units exceeding the load imbalance threshold between units, the unit is allowed to cross the restricted area.

[0024] Furthermore, the power shortage caused by the unit not crossing the forbidden area is greater than the power shortage caused by crossing the forbidden area, that is, the power shortage ratio is greater than 1. The expression of the power shortage ratio is:

[0025]

[0026] When the power shortage ratio is greater than 1, crossing the prohibited area is allowed.

[0027] Furthermore, the current direction of crossing the forbidden zone is determined as follows: if the load is increased, the forbidden zone is crossed upwards, and if the active power is reduced, the forbidden zone is crossed downwards.

[0028] Furthermore, the target units that need to cross the restricted area are obtained in combination with the current direction of crossing the restricted area. The principle to be followed is: when the load is increased, the units with the lowest load rate are given priority to cross the restricted area to reduce the impact on other units; when the active power is reduced, the units with the highest load rate are given priority to cross the restricted area to make full use of the potential of the units.

[0029] On the premise of meeting the above principles, the economic efficiency of the units shall be taken into consideration, and the units with the lowest operating costs shall be given priority for operations across the restricted areas. At the same time, the operating status of the units shall also be taken into consideration, and the units in good operating status shall be given priority for operations across the restricted areas.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention can guide the unit to avoid the restricted area by accurately acquiring and processing the restricted area under different water heads, thereby reducing the wear of the unit and extending the service life of the unit. When the load of the whole plant cannot meet the scheduling requirements or the load between the units is seriously unbalanced, the restricted area crossing strategy proposed by the present invention can flexibly adjust the unit load while ensuring the safety of the unit, enhance the response ability of the hydropower station to the change of the grid load, and ensure the stable operation of the power system.

[0032] The implementation of the present invention relies on accurate calculation of the restricted area and advanced active power distribution algorithm, which helps to improve the automation and intelligence level of the hydropower station, reduce manual intervention, and improve the accuracy and efficiency of operation management, which is of great significance to improving the overall operation efficiency of the hydropower station. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a flow chart of a method for distributing active power of a hydroelectric unit across a prohibited area.

[0034] Figure 2 Schematic diagram of the interpolation algorithm of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, a method for distributing active power of a hydropower unit across a prohibited zone according to the present invention is shown, and the method comprises:

[0037] Step 1: Obtain the prohibited areas of the hydropower station units under different known water heads, and obtain the prohibited areas under unknown water heads through interpolation algorithm.

[0038] Step 2: When the active power given value of the whole plant changes, the active power of the units is distributed according to the active power distribution principle.

[0039] Step 3: When the plant load cannot meet the dispatching requirements in the current operating area, crossing the restricted area is allowed.

[0040] Step 4, setting the dead zone for crossing the forbidden zone and the load imbalance threshold between units, and obtaining the target unit that needs to cross the forbidden zone in combination with the current direction of crossing the forbidden zone.

[0041] The prohibited areas under various working conditions are obtained through interpolation algorithms, including:

[0042] When the number of prohibited areas under the two adjacent water heads is the same, the number of prohibited areas under the current water head is consistent with that under the adjacent water heads:

[0043]

[0044] Among them, P 禁运,i is the power of the ith restricted area under the current water head, P 禁运,i,前 and P 禁运,i,后 are the power of the ith restricted area under the front and rear water heads, H is the current water head, and H 前 and H 后 They are front and rear water heads respectively;

[0045] When the number of restricted areas under the two adjacent water heads is different, the number of restricted areas under the front and rear water heads is set to be n, and the number of restricted areas under the front and rear water heads is set to be m; if the current water head is close to the water head with fewer restricted areas between the front and rear water heads, the number of restricted areas under the current water head is n, otherwise it is m:

[0046]

[0047] Among them, when i≤n, the power of the restricted area of ​​the previous water head is used for interpolation. When m≥i>n, the power P of the i-th restricted area under the water head with more restricted areas before and after the water head is directly used. 禁运,i,多 .

[0048] It should be noted that after obtaining the original prohibited areas under the corresponding water heads and operating conditions, the prohibited areas under various operating conditions are obtained by the following engineering method; when the numbers of prohibited areas under the two adjacent water heads are the same, they are obtained by interpolation in the order of the prohibited areas.

[0049] When the number of prohibited areas under the two adjacent water heads is different, such as Figure 2 As shown, it is a schematic diagram of the interpolation algorithm of the present invention; if it is known that there are 2 restricted areas at a water head of 76 meters and 3 restricted areas at a water head of 78 meters, and the restricted areas under a water head of 77.2 meters are to be sought, then 3 restricted areas are used for a water head of 77.2 meters; the first two restricted areas are obtained by linear interpolation of the 2 restricted areas at a water head of 76 meters and the first two restricted areas at a water head of 78 meters, and the third restricted area is obtained by linear interpolation of the 78-meter restricted area. If there are two restricted areas under a water head of 76.5 meters, the 2 restricted areas under a water head of 76 meters are used, and the solution method is to obtain the restricted areas by linear interpolation of the 2 restricted areas at a water head of 76 meters and the first two restricted areas at a water head of 78 meters.

[0050] The active power distribution principle includes: pre-defining the active power regulation step of the unit, and when the active power given value of the whole plant changes, judging whether the change is an increase in load or a decrease in active power.

[0051] If the load is increased, the unit with the smallest active power distribution value last time will be selected; if the increase is within the adjustment step range and does not enter the prohibited area and does not exceed the active power upper limit, only one unit needs to be allocated to complete the adjustment; otherwise, the remaining load will be allocated to the unit with the second smallest active power distribution value last time, and the same judgment will be made until the active power increase is allocated.

[0052] If active power is reduced, the unit with the largest active power distribution value last time will be selected; if the reduction is within the adjustment step range and does not enter the prohibited area and does not exceed the active power upper limit, only one unit needs to be allocated to complete the adjustment; otherwise, the remaining load will be allocated to the unit with the second largest active power distribution value last time, and the same judgment will be made until the active power reduction is allocated.

[0053] It should be noted that the following principles are considered in active power distribution. These principles are listed in order of priority: 1) The unit cannot operate in the prohibited area; 2) The prohibited area cannot be crossed frequently; 3) When the given total active power is greater than the actual total active power, the unit should not reduce the load as much as possible; when the given total active power is less than the actual total active power, the unit should not increase the load as much as possible; 4) The unit cannot be adjusted frequently (small load changes are moved by 1 or 2 units); 5) Optimize efficiency.

[0054] In order to reduce unit wear, the following principles are adopted: 1) Only change the set value of one or two machines within the predetermined power range.

[0055] 2) Increase the adjustment time interval. 3) Predefine an appropriate active power adjustment step size for each machine (such as 40MW).

[0056] When the active power set value of the whole plant changes, such as when the load increases, the unit with the smallest active power distribution value last time is selected. If the increment is within the adjustment step range, and does not enter the prohibited area and does not exceed the upper limit of active power, only one unit is allocated to complete the adjustment amount; otherwise, the remaining load is allocated to the unit with the second smallest active power distribution value last time, and the same judgment is made. If the distribution cannot be completed, the next unit is replaced until the active power increment is distributed; when reducing active power, the unit with the largest active power distribution last time is reduced first, and the same strategy is adopted for the others. Setting an appropriate active power adjustment step can reduce the number of units participating in the adjustment for a change in the active power set value, thereby reducing unit wear. If the active power adjustment step is set to be very small, it becomes an average distribution.

[0057] The dispatching requirements include: when the power shortage caused by the unit not crossing the restricted area is greater than the power shortage caused by crossing the restricted area, or when there is a serious load imbalance between units, resulting in the active power difference between units exceeding the load imbalance threshold between units, the unit is allowed to cross the restricted area.

[0058] The power shortage caused by the unit not crossing the forbidden area is greater than the power shortage caused by crossing the forbidden area, that is, the power shortage ratio is greater than 1. The expression of the power shortage ratio is:

[0059]

[0060] When the power shortage ratio is greater than 1, crossing the prohibited area is allowed.

[0061] The current direction of crossing the forbidden zone is determined as follows: if the load is increased, the forbidden zone is crossed upwards; if the active power is reduced, the forbidden zone is crossed downwards.

[0062] Combined with the current direction of crossing the restricted area, the target units that need to cross the restricted area are obtained. The principle to be followed is: when the load is increased, the unit with the lowest load rate is given priority to cross the restricted area to reduce the impact on other units; when the active power is reduced, the unit with the highest load rate is given priority to cross the restricted area to make full use of the unit potential.

[0063] On the premise of meeting the above principles, the economic efficiency of the units shall be taken into consideration, and the units with the lowest operating costs shall be given priority for operations across the restricted areas. At the same time, the operating status of the units shall also be taken into consideration, and the units in good operating status shall be given priority for operations across the restricted areas.

[0064] When the load of the entire plant cannot meet the dispatching requirements in the current operating area or the efficiency is too low, the unit needs to cross the forbidden area. The following principles need to be followed when crossing the forbidden area: 1) As few units as possible should cross the forbidden area; 2) The forbidden area should not be crossed frequently. In order to reduce unit wear and tear and maximize power plant efficiency, AGC crosses the forbidden area in the following two situations: 1) The power shortage caused by the unit not crossing the forbidden area is greater than the power shortage caused by crossing the forbidden area. 2) The load between units is seriously unbalanced, and the active power difference between units exceeds the preset value.

[0065] For example, if the adjustable operating range of the unit is 300-700MW, the prohibited zone of the unit is 450-510MW, the dead zone across the prohibited zone is 20MW, the load imbalance judgment value between units is 110MW, and the step length of increasing active power of a single unit is 40MW. Take three units as an example; Table 1 shows the load increase to cross the prohibited zone. Currently, the three units are all 400MW, the given value is 1200MW, and the active power given value is increased in steps of 50MW.

[0066] Table 1: Load increase upward across the prohibited area

[0067]

[0068]

[0069] Table 2 shows the reduction of active power to cross the prohibited area. Currently, the three units are all 550MW, the given value is 1650MW, and the active power given value is reduced in steps of 50MW.

[0070]

[0071]

[0072] Carry out real-time monitoring of the target unit to ensure its safe and stable operation during the operation across the restricted area; when the target unit completes the operation across the restricted area, promptly adjust the load distribution of other units to maintain the load balance of the entire plant; set a frequency limit for the unit's operation across the restricted area to avoid the impact of frequent crossing of the restricted area on the unit's life.

[0073] The real-time monitoring includes: monitoring the key parameters of the unit such as water head, flow, speed, vibration, etc.; analyzing the monitored parameters to determine whether the unit is within the safe operating range; taking timely measures when abnormal conditions are found, such as reducing the unit load, adjusting the operating strategy, etc. The load distribution adjustment of other units includes: recalculating the active power distribution of the whole plant according to the actual operating conditions of the target unit after crossing the restricted area; adjusting the load distribution of other units to ensure the balance of the whole plant load and the stable operation of the unit; in the adjustment process, giving priority to the economy and operating status of the unit.

[0074] In addition, in daily control, it is necessary to conduct regular performance evaluations on the units, and carry out necessary maintenance and overhaul of the units based on the evaluation results; establish a unit operation database to record the historical operation data of the units, and provide a basis for subsequent operation optimization and decision-making; combine actual operating conditions and dispatch requirements to continuously optimize the active power distribution strategy and improve the operating efficiency and economic benefits of the hydropower station.

[0075] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for distributing active power of hydropower units across prohibited areas. It is characterized in that The method comprises: Step 1, obtaining the prohibited areas of the hydropower station units under different known water heads, and obtaining the prohibited areas under unknown water heads by using an interpolation algorithm; Step 2: when the active power given value of the whole plant changes, the active power of the units is distributed according to the active power distribution principle; Step 3: When the plant load cannot meet the dispatching requirements in the current operation area, it is allowed to cross the prohibited area; Step 4, setting the dead zone for crossing the forbidden zone and the load imbalance threshold between units, and obtaining the target unit that needs to cross the forbidden zone in combination with the current direction of crossing the forbidden zone.

2. A method for distributing active power of hydropower units across prohibited areas according to claim 1, It is characterized in that The prohibited areas under various working conditions are obtained through interpolation algorithms, including: When the number of prohibited areas under the two adjacent water heads is the same, the number of prohibited areas under the current water head is consistent with that under the adjacent water heads: Among them, P 禁运,i is the power of the ith restricted area under the current water head, P 禁运,i,前 and P 禁运,i,后 are the power of the ith restricted area under the front and rear water heads, H is the current water head, and H 前 and H 后 They are front and rear water heads respectively; When the number of restricted areas under the two adjacent water heads is different, the number of restricted areas under the front and rear water heads is set to be n, and the number of restricted areas under the front and rear water heads is set to be m; if the current water head is close to the water head with fewer restricted areas between the front and rear water heads, the number of restricted areas under the current water head is n, otherwise it is m: Among them, when i≤n, the power of the restricted area of ​​the previous water head is used for interpolation. When m≥i>n, the power P of the i-th restricted area under the water head with more restricted areas before and after the water head is directly used. 禁运,i,多 .

3. A method for distributing active power of hydropower units across prohibited areas according to claim 2, It is characterized in that The active power distribution principles include: Predefine the active power regulation step of the unit, and when the active power given value of the whole plant changes, determine whether the change is an increase in load or a decrease in active power; If the load is increased, the unit with the smallest active power distribution value last time is selected; if the increment is within the adjustment step range, and does not enter the prohibited area and does not exceed the active power upper limit, only one unit is allocated to complete the adjustment amount; otherwise, the remaining load is allocated to the unit with the second smallest active power distribution value last time, and the same judgment is performed until the active power increment is allocated; If active power is reduced, the unit with the largest active power distribution value last time will be selected; if the reduction is within the adjustment step range and does not enter the prohibited area and does not exceed the active power upper limit, only one unit needs to be allocated to complete the adjustment; otherwise, the remaining load will be allocated to the unit with the second largest active power distribution value last time, and the same judgment will be made until the active power reduction is allocated.

4. A method for distributing active power of hydropower units across prohibited areas according to claim 3, It is characterized in that The dispatching requirements include: when the power shortage caused by the unit not crossing the restricted area is greater than the power shortage caused by crossing the restricted area, or when there is a serious load imbalance between units, resulting in the active power difference between units exceeding the load imbalance threshold between units, the unit is allowed to cross the restricted area.

5. A method for distributing active power of hydropower units across prohibited areas according to claim 4, It is characterized in that The power shortage caused by the unit not crossing the forbidden area is greater than the power shortage caused by crossing the forbidden area, that is, the power shortage ratio is greater than 1. The expression of the power shortage ratio is: When the power shortage ratio is greater than 1, crossing the prohibited area is allowed.

6. A method for distributing active power of hydropower units across prohibited areas according to claim 4, It is characterized in that The current direction of crossing the forbidden zone is determined as follows: if the load is increased, the forbidden zone is crossed upwards; if the active power is reduced, the forbidden zone is crossed downwards.

7. A method for distributing active power of hydropower units across prohibited areas according to claim 5, It is characterized in that Combined with the current direction of crossing the restricted zone, the target units that need to cross the restricted zone are obtained. The principle to be followed is: when increasing the load, the unit with the lowest load rate is given priority to cross the restricted zone to reduce the impact on other units; when reducing the active power, the unit with the highest load rate is given priority to cross the restricted zone to make full use of the unit potential; On the premise of meeting the above principles, the economic efficiency of the units shall be taken into consideration, and the units with the lowest operating costs shall be given priority for operations across the restricted areas. At the same time, the operating status of the units shall also be taken into consideration, and the units in good operating status shall be given priority for operations across the restricted areas.

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