Control method for improving small-amplitude active power regulation performance of hydraulic power plant

Abstract

The invention relates to a control method for improving small-amplitude active power regulation performance of a hydraulic power plant, which comprises the following steps of: adding a unit power stability evaluation index change trend into unit small load distribution priority calculation, comprehensively evaluating the power stability of each load point according to the power fluctuation condition of a single machine, and calculating the small-amplitude active power regulation performance of the hydraulic power plant. And the priority is correspondingly given according to the predicted change condition of the power stability of the unit after the small load power regulation is executed, and the unit selection of small load distribution is optimized. Compared with the prior art, the small-load distribution unit priority calculation process is optimized by combining the power stability difference of each unit, so that the AGC hydraulic power plant put into the whole plant can better meet the small-amplitude active power regulation requirement.

Description

Technical Field

[0001] The invention relates to a hydroelectric power generation control technology, and in particular to a control method for improving the small-amplitude active power regulation performance of a hydroelectric power plant. Background Art

[0002] The power stability of hydropower units will show differences in different load ranges and different operating stages after maintenance. For hydropower plants that have put the whole plant into AGC operation, if the changing trend of the unit power stability after small load adjustment is not dynamically considered, the stability of the total active power of the whole plant may deteriorate. For areas where the power control deviation will trigger the AGC action response performance assessment, the deterioration of the total active power stability of the whole plant will increase the frequency of AGC response assessment, and the small-scale AGC response performance will also be weakened by the power stability, which will eventually aggravate the AGC assessment penalty.

[0003] At present, the research on improving the small-scale AGC regulation performance of hydropower plants with full-plant AGC operation mainly focuses on the allocation strategy of the total active power command of the whole plant, the accuracy and stability of the power regulation of a single unit. The small load distribution strategy allocates all small-scale regulation needs to a single unit for execution, which not only reduces the frequency of unit regulation, but also effectively avoids the impact of power fluctuations on the AGC regulation performance of the whole plant when multiple units are adjusted at the same time. However, the current small load distribution generally does not adopt a separate unit priority calculation, and is still executed according to the priority of start-up and shutdown, that is, it mainly considers the cumulative running time of the unit, the shortest start / stop limit, the start / stop failure degradation and the manually set priority, etc., and the consideration of the trend of changes in unit power stability is insufficient, and there is a lot of room for improvement. In terms of improving the power regulation accuracy and stability of a single hydropower unit, current research mainly focuses on the inner-loop double-closed-loop power control model, power PID control parameter optimization, power measurement damping filtering, guide vane control linearization correction, etc. However, it is still difficult to overcome the power fluctuations caused by factors such as inherent guide vane mechanical characteristics and flow channel hydraulic characteristics, and it is impossible to maintain a high level of power stability for all units in the power plant in all operating stages and all load ranges after repair. The actual assessment scores show that the use of conventional small load distribution strategies and improving the power regulation performance of a single unit still have a large AGC assessment risk. Therefore, it is necessary to dynamically select the unit priority according to the trend of power stability changes during AGC small load regulation.

[0004] After searching, Chinese patent publication number CN111740452A discloses a method for controlling active power of hydropower units in a single recommended operating area. It specifically discloses that on the basis of subdividing the distribution of different vibration zones of hydropower units, an AGC allocation calculation method based on trial is adopted to avoid the dimensionality curse problem of the exhaustive method. When the AGC active distribution value is sent to each unit, the change part of the active setting value of the reverse balanced unit is sent in steps, so as to avoid the possible fluctuation of the active power of the whole station during the power balance between units. However, this method does not take into account the power fluctuation of the hydropower unit itself. When facing the working condition of small-amplitude active power regulation of the whole plant, there is still the problem of insufficient AGC regulation performance.

[0005] Therefore, the existing technology has insufficient consideration for the optimization of small-amplitude AGC regulation performance in hydropower plants that have invested in plant-wide AGC, and the small load distribution has not fully considered the changing trend of the power stability of each unit. Even if the accuracy and stability of power regulation of all units are improved, due to the influence of inherent power control deviation, it is still impossible to maximize the stability of the total active power of the whole plant when implementing the small load regulation strategy, and there is still a high AGC assessment risk. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a control method for improving the small-amplitude active power regulation performance of a hydropower plant.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] According to one aspect of the present invention, there is provided a control method for improving the small-amplitude active power regulation performance of a hydropower plant. The method incorporates the changing trend of the unit power stability evaluation index into the unit small load distribution priority calculation, performs a comprehensive evaluation of the power stability of each load point based on the power fluctuation of a single machine, assigns a priority accordingly based on the expected change in the unit power stability after executing small load power regulation, and optimizes the unit selection for small load distribution.

[0009] As a preferred technical solution, the method comprises the following steps:

[0010] Step S1, defining the unit power stability priority for small load distribution unit priority selection;

[0011] Step S2, regularly and automatically counting the power stability of all operational load points of the hydropower unit, and calculating the comprehensive power stability index of each load point of the unit;

[0012] Step S3, dividing the operating range of the unit into load segments based on the distribution of the power comprehensive stability index;

[0013] Step S4, based on the subdivision of the load segments within the unit's operable range, according to the expected changes in the comprehensive stability indicators of the load segments before and after each unit executes the small load instruction, calculate the unit power stability priority under the current small-amplitude regulation demand.

[0014] As a preferred technical solution, step S2 specifically includes:

[0015] Step S201, regularly and automatically counting, recording and updating the power control deviation of each load point where the power setting value of all operating intervals of the units in the hydropower plant remains unchanged for more than a set time;

[0016] Step S202, based on the power control deviation, calculate the power comprehensive stability index characterizing the power control deviation of each load point within the operating range of the unit.

[0017] As a preferred technical solution, the comprehensive power stability index is a function that characterizes the statistical index of power stability at each load point.

[0018] As a preferred technical solution, the unit operating range in step S3 includes a non-vibration area and a non-restricted operating area.

[0019] As a preferred technical solution, step S3 specifically includes:

[0020] Step S301, counting the distribution of the power comprehensive stability index of the power control deviation of each load point;

[0021] Step S302, according to the distribution of stability indicators, a threshold set is set to divide the operating ranges of all units into load segments.

[0022] As a preferred technical solution, the threshold in step S302 is set according to the distribution of the comprehensive power stability index of all units.

[0023] As a preferred technical solution, step S4 specifically includes:

[0024] Step S401, sorting the light load allocation priorities of the units according to the changes in the comprehensive stability index of the load segment where each unit is located before and after executing the light load instruction;

[0025] Step S402, if the predicted improvement degree of the comprehensive stability index of the load segment where the unit is located before and after executing the small load instruction is greater, the small load allocation priority is higher;

[0026] Step S403: If the improvement of the power stability index is the same after executing the small load instruction, the unit with short response time and fast regulation rate is preferentially selected to perform small load regulation.

[0027] As a preferred technical solution, the small load distribution does not involve start-up and shutdown, and its priority selection is biased towards performance selection.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1) The present invention incorporates the changing trend of the unit power stability evaluation index into the unit small load allocation priority calculation, thereby weakening the impact of the unit power stability difference on the AGC response performance of the whole plant.

[0030] 2) The present invention dynamically considers the impact of power stability differences in different operating stages and different load intervals after unit repair on the AGC response performance of the entire hydropower plant, introduces power stability priority to optimize the small load allocation priority calculation, and solves the problem of poor small-amplitude AGC regulation performance of the hydropower plant with full-plant AGC. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a specific flow chart of the control method of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0033] At present, the processing method for improving the response performance of small-amplitude regulation instructions of hydropower plants at the small-load distribution strategy level has not taken into account the potential constraints of the dynamic power stability of each unit in the power plant on the total active power regulation performance of the whole plant. The present invention optimizes the priority calculation method of small-load distribution units based on the power stability differences of each unit, so that the hydropower plant with AGC in the whole plant can better meet the demand for small-amplitude active power regulation.

[0034] The present invention incorporates the change trend of the unit power stability evaluation index into the unit small load allocation priority calculation, weakening the impact of the unit power stability difference on the AGC response performance of the whole plant. According to the power fluctuation of a single machine, the power stability of each load point is comprehensively evaluated, and the priority is assigned accordingly according to the expected change of the unit power stability after the small load power adjustment is performed, so as to optimize the selection of units for small load distribution, improve the performance of small-amplitude AGC adjustment of hydropower plants with full-plant AGC, and reduce the AGC assessment score of power plants.

[0035] like Figure 1 As shown, in one embodiment of the present invention,

[0036] Step 1: Define the unit power stability priority for small load distribution unit priority selection.

[0037] Step 2, regularly and automatically count, record, and update the power control feedback deviation of each load point where all power setting values ​​in all operable intervals of all units in the power plant remain unchanged for more than 5 minutes;

[0038] According to the power control deviation, the comprehensive power stability index characterizing the power control deviation of each load point within the operating range of the unit is calculated.

[0039] It should be noted that the comprehensive power stability index is a function that characterizes the statistical index of power stability at each load point. In this embodiment, the maximum deviation from the power setting value is used as the comprehensive power stability index.

[0040] Step 3, counting the distribution of the power comprehensive stability index of the power control deviation of each load point;

[0041] According to the distribution of stability indicators, a suitable threshold set is set to further divide the operating range of all units into load segments.

[0042] It should be noted that the threshold used to further divide the load operation range is set according to the distribution of the comprehensive power stability indicators of all units. When designing the function for calculating the power stability priority of the computer unit, it should be noted that the calculation result should be able to distinguish the differences in power stability in different subdivided intervals of different units.

[0043] Step 4: sort the small load allocation priorities of the units according to the changes in the comprehensive stability indicators of the load segments where each unit is located before and after executing the small load instruction.

[0044] The greater the expected improvement in the comprehensive stability index of the load segment before and after the unit executes the small load instruction, the higher the priority of small load allocation.

[0045] If the power stability index improves in the same way after executing the small load instruction, the units with short response time and fast regulation rate will be given priority to perform small load regulation.

[0046] It should be noted that since small load distribution does not involve starting and stopping the unit, its priority selection should focus on performance selection without considering factors such as the cumulative operating time of the unit.

[0047] In order to more clearly illustrate the technical solution and advantages of the present invention, a control method for improving the small-amplitude active power regulation performance of a hydropower plant provided by the present invention is further illustrated below.

[0048] Assume that a hydropower plant has three units with a single unit capacity of 300MW and a total capacity of 900MW. The vibration range of the units is 90-150MW. All three units are put into group operation on a daily basis. According to the comprehensive response performance of the single unit AGC, they are arranged from high to low as No. 3, No. 1, and No. 2.

[0049] First, the power control deviations of the three units with stable durations greater than 5 minutes under each power command in the load ranges of 0-90 and 150-300MW are automatically counted, recorded and updated regularly.

[0050] According to the recorded power control deviation data, the maximum deviation from the power setting value is taken as the power comprehensive stability index, and the power comprehensive stability index of the three units in the operating load range of 0-90 and 150-300MW is counted. It is assumed that the statistical results are shown in Table 1 below:

[0051] Table 1

[0052]

[0053] Secondly, according to the distribution of the comprehensive power stability index in Table 1, the threshold set {1, 2, 3, 4, 5} is set to further divide the load segments of the respective operable intervals of all units. The specific division results are shown in Table 2.

[0054] Table 2

[0055] Area division number Unit 1 Unit 2 Unit 3 1 0~60(3MW) 0~60(3MW) 0~60(3MW) 2 60~180(2MW) 60~90(1MW) 60~90(4MW) 3 180~240(3MW) 150~180(2MW) 150~300(2MW) 4 240~300(2MW) 180~240(4MW) 5 240~300(2MW)

[0056] Finally, the unit that executes the small load instruction is selected according to the predicted value of the improvement of the comprehensive power stability index after executing the small load instruction. The greater the predicted improvement of the comprehensive power stability index, the higher the priority of being selected to execute the small load allocation strategy. If the improvement of the power stability index is the same, the unit with short response time and fast adjustment rate is preferred to execute the small load strategy. The specific selection results are shown in Table 3:

[0057] Table 3

[0058]

[0059] The optimization result finally selected by the method and system of the present invention dynamically considers the influence of the power stability difference in different operating stages and different load intervals after the unit repair on the AGC response performance of the whole hydropower plant, introduces the power stability priority to optimize the small load distribution priority calculation, solves the problem of poor small-amplitude AGC regulation performance of the hydropower plant with full-plant AGC, and reduces the AGC assessment score.

[0060] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A control method for improving the small-amplitude active power regulation performance of a hydropower plant, characterized in that: This method incorporates the changing trend of the unit power stability evaluation index into the unit small load distribution priority calculation, conducts a comprehensive evaluation of the power stability of each load point according to the power fluctuation of a single machine, and assigns priority accordingly according to the expected change in the unit power stability after executing small load power adjustment, thereby optimizing the unit selection for small load distribution.

2. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 1, characterized in that: The method comprises the following steps: Step S1, defining the unit power stability priority for small load distribution unit priority selection; Step S2, regularly and automatically counting the power stability of all operational load points of the hydropower unit, and calculating the comprehensive power stability index of each load point of the unit; Step S3, dividing the operating range of the unit into load segments based on the distribution of the power comprehensive stability index; Step S4, based on the subdivision of the load segments within the unit's operable range, according to the expected changes in the comprehensive stability indicators of the load segments before and after each unit executes the small load instruction, calculate the unit power stability priority under the current small-amplitude regulation demand.

3. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 2, characterized in that: The step S2 specifically includes: Step S201, regularly and automatically counting, recording and updating the power control deviation of each load point where the power setting value of all operating intervals of the units in the hydropower plant remains unchanged for more than a set time; Step S202, based on the power control deviation, calculate the power comprehensive stability index characterizing the power control deviation of each load point within the operating range of the unit.

4. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 3, characterized in that: The power comprehensive stability index is a function that characterizes the statistical index of power stability at each load point.

5. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 2, characterized in that: The unit operable range in step S3 includes a non-vibration zone and an unrestricted operation zone.

6. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 2, characterized in that: The step S3 specifically includes: Step S301, counting the distribution of the power comprehensive stability index of the power control deviation of each load point; Step S302, according to the distribution of stability indicators, a threshold set is set to divide the operating ranges of all units into load segments.

7. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 6, characterized in that: The threshold in step S302 is set according to the distribution of the comprehensive power stability index of all units.

8. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 2, characterized in that: The step S4 specifically includes: Step S401, sorting the light load allocation priorities of the units according to the changes in the comprehensive stability index of the load segment where each unit is located before and after executing the light load instruction; Step S402, if the predicted improvement degree of the comprehensive stability index of the load segment where the unit is located before and after executing the small load instruction is greater, the small load allocation priority is higher; Step S403: If the improvement of the power stability index is the same after executing the small load instruction, the unit with short response time and fast regulation rate is preferentially selected to perform small load regulation.

9. A control method for improving the small-amplitude active power regulation performance of a hydropower plant according to claim 8, characterized in that: The small load distribution does not involve starting and stopping, and its priority selection is biased towards performance selection.

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