Hydropower medium-and-long-term peak regulation scheduling method considering time period contribution degree

Abstract

The invention provides a hydropower medium-and-long-term peak regulation scheduling method considering time period contribution degree, which comprises the following steps of: firstly, performing variable-scale segmentation on a scheduling period according to amplitude-fluctuation characteristics of a power grid load in a medium-and-long-term scale, then setting the time period contribution degree, and obtaining a hydropower station scheduling process under a corresponding scale by adopting a variable-scale load shedding method; the hydropower peak regulation capacity in the dispatching period can be distributed in a targeted mode, dimensionality reduction solving of cascade hydropower peak regulation dispatching is facilitated, and the dispatching scheme calculation efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid planning and dispatching operation, and specifically relates to a medium- and long-term peak-shaving dispatching method for hydropower taking into account the contribution of time periods. Background Art

[0002] In the context of accelerating the construction of a new power system, the characteristics of the power system's diversified entities, complex grid forms, and diversified operation modes are becoming increasingly obvious, and the peak-shaving pressure of the power grid at different time scales is increasing on both the source and the load sides. As a dual provider of power supply and flexible regulation within the system, hydropower peak-shaving methods are also facing new challenges. How to effectively utilize the flexibility of hydropower, optimize the allocation of daily hydropower electricity according to the medium- and long-term characteristics of the grid load, and ensure that the grid has sufficient peak-shaving capacity during the "peak winter", "peak summer" and other critical periods is the key to the medium- and long-term scheduling of hydropower stations under the new situation.

[0003] When making medium- and long-term dispatching plans for power grids, dispatchers usually have variable-scale peak-shaving needs: based on load and new energy forecasts, they predict peak-shaving needs, hoping to maximize the hydropower peak-shaving effect within a certain period of time without affecting the normal operation of hydropower in the later period. Conventional dispatching methods with fixed steps such as days and ten days are no longer applicable. In addition, the medium- and long-term loads of power grids usually show greater amplitude and volatility differences in time than short-term loads. Conventional medium- and long-term optimized dispatching usually guides the peak-shaving capacity to gather at the highest load, highlighting the amplitude characteristics but easily ignoring the volatility characteristics. This may result in insufficient peak-shaving capacity during periods of strong load fluctuations, inability to smooth fluctuations, and increased difficulty and cost of power grid regulation.

[0004] The Chinese patent "CN106655280A, a short-term peak-shaving model and solution method for cascade hydropower based on power control" provides a short-term peak-shaving model for cascade hydropower based on power control. It scientifically arranges the working position of the hydropower station in the power grid through load reconstruction, heuristic load shedding and other methods, and can reasonably distribute the power of the hydropower system. However, it is only suitable for short-term scales and does not consider the characteristic differences of medium and long-term loads.

[0005] The technical solution described in the Chinese patent "CN115169701A Cascade Hydropower Short-term Optimal Scheduling Method Based on Segmented Load Reconstruction Strategy" divides the load horizontally into segmented loads with peak and valley characteristics and frequently fluctuating residual load processes, and allocates them to different hydropower stations. It solves the dimensionality curse of large-scale hydropower short-term optimal scheduling from the load space dimension, but cannot solve the requirement of fixing a certain peak-shaving depth for hydropower in special time periods. Summary of the invention

[0006] In view of the above problems, the present invention provides a medium- and long-term hydropower peak-shaving scheduling method taking into account the contribution of time periods. First, the scheduling period is divided into variable scales according to the amplitude-fluctuation characteristics of the power grid load in the medium and long term, and then the time period contribution is set. The variable scale load shedding method is used to obtain the hydropower station scheduling process at the corresponding scale. This method can not only allocate the hydropower peak-shaving capacity during the scheduling period in a targeted manner, but also is conducive to the dimensionality reduction solution of cascade hydropower peak-shaving scheduling, thereby improving the calculation efficiency of the scheduling scheme.

[0007] In order to realize the above technical features, the purpose of the present invention is to achieve: a method for medium- and long-term peak load regulation of hydropower considering the contribution of time periods, comprising the following steps:

[0008] S1, initialization of input data and power station parameters;

[0009] S2, load cut-off point extraction;

[0010] S3, cut-off point screening;

[0011] S4, full cycle segmentation;

[0012] S5, set time period contribution;

[0013] S6, shedding load in sections.

[0014] The input data and power station parameters initialized in S1 include: medium- and long-term load forecast data and hydropower peak-shaving capacity data; wherein the hydropower peak-shaving capacity data is set to the installed capacity of the hydropower station, or is set separately in different time periods according to the actual output capacity; wherein the installed capacity of the hydropower station is a constant.

[0015] The load demarcation point extraction in S2 is to propose the basic judgment conditions of the load characteristic change point based on the load amplitude and fluctuation quantitative index, and extract it;

[0016] Specifically, the load extreme value points have clear peak and valley physical meanings, including load characteristic changes, and the load sequence extreme value points are selected as the initial characteristic sequence:

[0017] Where t is the cutoff point, n is the total number of cutoff points, and l is the extreme value of the load sequence at the corresponding cutoff point.

[0018] The demarcation point screening in S3 is to retain only the demarcation points with load trend turning significance according to the peak regulation capacity of the hydropower station, and filter the demarcation interference caused by small fluctuations in the load curve;

[0019] The full cycle segmentation in S4 is to segment the original load into time segments according to the reserved landmark points to obtain multiple scheduling periods;

[0020] Specifically, based on the frequent medium- and long-term load fluctuations and the large number of sequence data points obtained in step S2, some data points are only generated by small medium- and long-term load fluctuations and do not have the significance of a load trend turning point. A load sequence smoothing strategy is used to superimpose a hydropower station peak-shaving capacity screening strategy to screen out the final dividing point and divide the scheduling period into a set of continuous time periods by the dividing point.

[0021] It is characterized in that the load sequence smoothing strategy is specifically:

[0022] First, define the load amplitude characteristic as the amplitude ratio A, and the fluctuation characteristic as the minimum time interval R of the extreme points. If the amplitude ratio is less than A and the time interval is less than R, then it is eliminated and from Continue to judge, as shown in formula (1):

[0023]

[0024] In the formula, t is the dividing point, i is one of the dividing points, A is the amplitude ratio, R is the minimum time interval of the extreme point, l is the extreme value of the load sequence at the corresponding dividing point, p is the output of the hydropower station at the dividing point, and Δt is.

[0025] The peak load capacity screening strategy of the hydropower station is specifically as follows:

[0026] The left and right sides of the dividing point belong to different time periods. In order to ensure the consistency of the output of the hydropower station in different sections around the dividing point, the heuristic load shedding process is considered. The working position of the hydropower station in different time periods is jointly determined by the load peak value and the hydropower peak regulation capacity during the scheduling period. When the dividing point belongs to the time period below the working position of the hydropower station, the output of the hydropower station is the minimum output. Only the dividing point in this period is retained to meet the consistency of the output of the dividing point, as shown in formula (2):

[0027] P t - =P t + (2)

[0028] Where P t - is the power output of the hydropower station calculated in the period to the left of the demarcation point t, P t + It is the power output of the hydropower station calculated in the period to the right of the dividing point t.

[0029] Calculate the allowable range of water levels at the end of different scheduling periods: According to the operation constraints of the power station, the maximum allowable water level and the minimum operable water level at the end of different time periods are recursively calculated forward and backward to form the water level range at the end of this period.

[0030] Setting the time period contribution in S5 is the dispatcher setting the hydropower peak-shaving capacity for each dispatch period after segmentation, so as to achieve targeted allocation of hydropower peak-shaving capacity within the dispatch period;

[0031] Specifically, it includes: setting the peak load regulation capacity of hydropower in different periods, as shown in formula (3), P n peak is the peak load regulation capacity of the hydropower station in segment n, is the minimum output of the hydropower station in segment n, is the maximum output of the hydropower station in segment n, λ is the contribution degree of the period, which can be set manually. The larger λ is, the greater the peak regulation depth of segment n is;

[0032]

[0033] The load shedding in step S6 is to use the load shedding method in different sections according to the peak load regulation capacity of the hydropower in the section, and solve the hydropower operation process in the section;

[0034] Specifically, it includes: independently using a heuristic load shedding method for different sections. After the first load shedding in each section, the final water level of the period is calculated to check whether it is within the allowable range of the final water level. If it is lower than the lower limit, λ is reduced until the final water level of the period meets the lower limit requirement; if the water level is higher than the allowable upper limit, λ is increased until the final water level of the period meets the upper limit requirement. The calculation is performed section by section until the hydropower output plan for different periods in the entire scheduling cycle is obtained.

[0035] The detailed steps of load cutoff point extraction and cutoff point screening are as follows:

[0036] Step 1. Extract the extreme points of the load sequence and generate the extreme sequence L′;

[0037] Step 2. Set the current time t = 0, define the load amplitude characteristic as the amplitude ratio A, and the fluctuation characteristic as the minimum time interval R of the extreme value point. If two adjacent points in the extreme value sequence If the amplitude ratio is less than L and the time interval is less than R, then it is eliminated and from Continue to judge, as shown in formula (4), and get the preliminary demarcation point sequence L s ;

[0038]

[0039] Step 3. In L s Based on this, the maximum value points are eliminated to obtain the boundary sequence L' that needs to be screened for consistency s ={(t s,1 ,l s,1 ),(t s,2 ,l s,2 ),...,(ts,n ,l s,n )}, the scheduling period is t s,1 ,t s,2 ,...,t s,n The entire dispatching period is divided into sections as the demarcation point, and the installed capacity of the hydropower station is used as the peak-shaving capacity of each period. s,1 ,t s,2 ,...,t s,n Verify whether the hydropower station meets the output consistency at this moment, as shown in formula (5); traverse L' s All time points in the equation (5) are eliminated if they do not satisfy the equation (5). Finally, the boundary sequence L is obtained. se ={(t se,1 ,l se,1 ),(t se,2 ,l se,2 ),...,(t se,I ,l s,I )};

[0040]

[0041] Step 4. Set the number of sub-periods i = 0, and calculate the allowable range of water levels at the end of different scheduling periods: According to the operating constraints such as power station output, water level, flow, etc., the maximum allowable water level and the minimum operable water level at the end of different periods are recursively calculated in the forward and reverse directions to form the water level range at the end of this period

[0042] Step 5. Set the time period contribution: Set the time period contribution λ of sub-period i i , calculate the peak load regulation capacity of hydropower during this period, as shown in the following formula:

[0043] P i peak =P i min +λ i ·(P i max -P i min ) (6)

[0044] Step 6. Variable scale load shedding: Adopt heuristic load shedding method, according to P i peak Determine the working position of the hydropower station, calculate the output during the period, and then calculate the final water level of the period to check whether it is within the allowable range of the final water level. If it is below the lower limit, reduce λ i Until the water level at the end of the period meets the lower limit requirement; if the water level is higher than the upper limit allowed, increase λ until the water level at the end of the period meets the upper limit requirement;

[0045] Step 7. Determine whether i=I. If so, the calculation ends. If not, set i=i+1 and repeat Step 4-Step 6 until the condition is met.

[0046] The present invention has the following beneficial effects:

[0047] The dispatching method proposed in the present invention can improve the coordination of water and electricity dispatching. By making the hydropower output curve closer to the grid load and the dispatcher's needs, the hydropower peak regulation can accurately improve the satisfaction of the grid load demand in all periods. The load demarcation point extraction, screening, and segmentation methods can ensure that the demarcation points with load trend turning significance are retained according to the peak regulation capacity of the hydropower station; the time period contribution can be set manually and dynamically to set the hydropower peak regulation capacity, realize the targeted allocation of hydropower peak regulation capacity during the dispatching period, and can effectively smooth load fluctuations and improve the overall peak regulation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0049] Figure 1 The figure is a flow chart of the method of the present invention.

[0050] Figure 2 It is a schematic diagram of the working position of the hydropower station of the present invention.

[0051] Figure 3 It is the load segmentation result of a certain area power grid in an embodiment of the present invention.

[0052] Figure 4 This is the actual operation process of a hydropower station in an embodiment of the present invention and the process obtained by the proposed method. DETAILED DESCRIPTION

[0053] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0054] Embodiment 1:

[0055] The present invention proposes a medium- and long-term peak-shaving dispatching method for hydropower considering the contribution of time periods. The method consists of several parts: load demarcation point extraction, demarcation point screening, full-cycle segmentation, setting time period contribution, and load shedding in sections. The load demarcation point extraction is to propose basic judgment conditions for load characteristic change points based on load amplitude and fluctuation quantitative indicators, and extract them; the demarcation point screening link is to retain only demarcation points with load trend turning significance according to the peak-shaving capacity of the hydropower station, and filter out demarcation interference caused by small fluctuations in the load curve; the full-cycle segmentation link is to segment the original load in time according to the retained landmark points to obtain multiple dispatching periods; setting time period contribution is for the dispatcher to set the hydropower peak-shaving capacity for each dispatching period after segmentation, so as to realize the targeted allocation of hydropower peak-shaving capacity within the dispatching period; load shedding in sections is to use the load shedding method in different sections according to the peak-shaving capacity of hydropower in this section, and solve the hydropower operation process in this section. The proposed method can improve the coordination of water and electricity dispatching, and accurately improve the satisfaction of hydropower peak regulation with grid load demand at all times by making the hydropower output curve closer to the grid load and dispatcher needs. Figure 1 shown.

[0056] Embodiment 2:

[0057] A method for medium- and long-term peak load regulation of hydropower considering time period contribution comprises the following steps:

[0058] S1, initialization of input data and power station parameters;

[0059] Including: medium- and long-term load forecast data and hydropower peak-shaving capacity data; wherein the hydropower peak-shaving capacity data is set as the installed capacity of the hydropower station, or is set separately in different time periods according to the actual output capacity; wherein the installed capacity of the hydropower station is a constant.

[0060] S2, load cut-off point extraction;

[0061] Load demarcation point extraction is to propose basic judgment conditions for load characteristic change points based on load amplitude and fluctuation quantitative indicators, and then extract them;

[0062] Specifically, the load extreme value points have clear peak and valley physical meanings, including load characteristic changes, and the load sequence extreme value points are selected as the initial characteristic sequence:

[0063] Where t is the cutoff point, n is the total number of cutoff points, and l is the extreme value of the load sequence at the corresponding cutoff point.

[0064] S3, cut-off point screening;

[0065] S4, full cycle segmentation;

[0066] The demarcation point screening in S3 is to retain only the demarcation points with load trend turning significance according to the peak regulation capacity of the hydropower station, and filter out the demarcation interference caused by small fluctuations in the load curve;

[0067] The full cycle segmentation in S4 is to segment the original load into time segments according to the reserved landmark points to obtain multiple scheduling periods;

[0068] Specifically, based on the frequent medium- and long-term load fluctuations and the large number of sequence data points obtained in step S2, some data points are only generated by small medium- and long-term load fluctuations and do not have the significance of a load trend turning point. A load sequence smoothing strategy is used to superimpose a hydropower station peak-shaving capacity screening strategy to screen out the final dividing point and divide the scheduling period into a set of continuous time periods by the dividing point.

[0069] The load sequence smoothing strategy is specifically as follows:

[0070] First, define the load amplitude characteristic as the amplitude ratio A, and the fluctuation characteristic as the minimum time interval R of the extreme points. If the amplitude ratio is less than A and the time interval is less than R, then it is eliminated and from Continue to judge, as shown in formula (1):

[0071]

[0072] In the formula, t is the dividing point, i is one of the dividing points, A is the amplitude ratio, R is the minimum time interval of the extreme point, l is the extreme value of the load sequence at the corresponding dividing point, p is the output of the hydropower station at the dividing point, and Δt is.

[0073] The peak load capacity screening strategy of the hydropower station is specifically as follows:

[0074] The left and right sides of the dividing point belong to different time periods. In order to ensure the consistency of the output of the hydropower station in different sections around the dividing point, the heuristic load shedding process is considered. The working position of the hydropower station in different time periods is jointly determined by the load peak value and the hydropower peak regulation capacity during the scheduling period. When the dividing point belongs to the time period below the working position of the hydropower station, the output of the hydropower station is the minimum output, such as Figure 2 The middle time period [0, t1), (t2, T] is shown. Only retaining the demarcation points in this type of time period can satisfy the consistency of the demarcation point output, as shown in formula (2);

[0075] P t - =P t + (2)

[0076] Where P t - is the power output of the hydropower station calculated in the period to the left of the demarcation point t, P t+ It is the power output of the hydropower station calculated in the period to the right of the dividing point t.

[0077] Calculate the allowable range of water levels at the end of different scheduling periods: According to the operation constraints of the power station, the maximum allowable water level and the minimum operable water level at the end of different time periods are recursively calculated forward and backward to form the water level range at the end of this period.

[0078] S5, set time period contribution;

[0079] The peak load regulation capacity of hydropower in different periods is set as shown in formula (3), P n peak is the peak load regulation capacity of the hydropower station in segment n, is the minimum output of the hydropower station in segment n, is the maximum output of the hydropower station in segment n, λ is the contribution degree of the period, which can be set manually. The larger λ is, the greater the peak regulation depth of segment n is;

[0080]

[0081] S6, shedding load in sections.

[0082] The heuristic load shedding method is used independently for different sections. After the first load shedding in each section, the final water level of the period is calculated to check whether it is within the allowable range of the final water level. If it is lower than the lower limit, λ is reduced until the final water level of the period meets the lower limit requirement; if the water level is higher than the allowable upper limit, λ is increased until the final water level of the period meets the upper limit requirement. The calculation is performed section by section until the hydropower output plan for different periods in the full scheduling cycle is obtained.

[0083] Embodiment 3:

[0084] The key point of the implementation plan is to propose a method for extracting and screening load demarcation points to finely define medium- and long-term peak-shaving demands, and to set time period contribution to achieve targeted allocation of hydropower peak-shaving capacity during the scheduling period.

[0085] Taking the load in a certain area as an example, the detailed steps of load classification using the proposed load cutoff point extraction and screening method are as follows:

[0086] Step 1. Extract the extreme points of the load sequence and generate the extreme sequence L′;

[0087] Step 2. Set the current time t = 0, define the load amplitude characteristic as the amplitude ratio A, and the fluctuation characteristic as the minimum time interval R of the extreme value point. If two adjacent points in the extreme value sequence If the amplitude ratio is less than L and the time interval is less than R, then it is eliminated and from Continue to judge, as shown in formula (4), and get the preliminary demarcation point sequence L s ;

[0088]

[0089] Step 3. In L s Based on this, the maximum value points are eliminated to obtain the boundary sequence L' that needs to be screened for consistency s ={(t s,1 ,l s,1 ),(t s,2 ,l s,2 ),...,(t s,n ,l s,n )}, the scheduling period is t s,1 ,t s,2 ,...,t s,n The entire dispatching period is divided into sections as the demarcation point, and the installed capacity of the hydropower station is used as the peak-shaving capacity of each period. s,1 ,t s,2 ,...,t s,n Verify whether the hydropower station meets the output consistency at this moment, as shown in formula (5); traverse L' s All time points in the equation (5) are eliminated if they do not satisfy the equation (5). Finally, the boundary sequence L is obtained. se ={(t se,1 ,l se,1 ),(t se,2 ,l se,2 ),...,(t se,I ,l s,I )};

[0090]

[0091] Step 4. Set the number of sub-periods i = 0, and calculate the allowable range of water levels at the end of different scheduling periods: According to the operating constraints such as power station output, water level, flow, etc., the maximum allowable water level and the minimum operable water level at the end of different periods are recursively calculated in the forward and reverse directions to form the water level range at the end of this period

[0092] Step 5. Set the time period contribution: Set the time period contribution λ of sub-period i i , calculate the peak load regulation capacity of hydropower during this period, as shown in the following formula:

[0093] P i peak =P i min +λ i ·(P i max -P i min ) (6)

[0094] Step 6. Variable scale load shedding: Adopt heuristic load shedding method, according to Pi peak Determine the working position of the hydropower station, calculate the output during the period, and then calculate the final water level of the period to check whether it is within the allowable range of the final water level. If it is below the lower limit, reduce λ i Until the water level at the end of the period meets the lower limit requirement; if the water level is higher than the upper limit allowed, increase λ until the water level at the end of the period meets the upper limit requirement;

[0095] Step 7. Determine whether i=I. If so, the calculation ends. If not, set i=i+1 and repeat Step 4-Step 6 until the condition is met.

[0096] Considering the actual application needs of a certain region, March 1 is set as the artificial segmentation point, and the proposed method is used for segmentation from March 1 to June 11. The load process in this region is as follows Figure 3 As shown, sub-periods 1 to 5 are obtained as Figure 4 shown.

[0097] Take a hydropower station in the region as an example. Figure 4 As shown in the figure, compared with the actual operation process, the output process obtained by the proposed method effectively adjusts the load peak value within the artificial segment 1 (this segment includes the peak of the load amplitude), and achieves the purpose of adjusting the peak-shaving effect in a certain period of time; at the same time, the segmentation method and the time period contribution setting in the remaining scheduling period can guide the peak-shaving capacity to be reasonably allocated in a manner that meets the scheduling needs of the dispatchers, effectively smoothing the small and frequent fluctuations of the load in certain periods, and avoiding the frequent shutdown of thermal power units caused by the large-scale generation of hydropower before the flood season occupying the consumption space, which can effectively alleviate the medium- and long-term peak-shaving pressure of the power grid from a global perspective.

Claims

1. A method for medium- and long-term peak load regulation of hydropower considering the contribution of time periods, characterized in that: The following steps are involved: S1, initialization of input data and power station parameters; S2, load cut-off point extraction; S3, cut-off point screening; S4, full cycle segmentation; S5, set time period contribution; S6, shedding load in sections.

2. According to claim 1, a method for medium- and long-term peak load regulation of hydropower considering time period contribution is characterized in that: The input data and power station parameters initialized in S1 include: medium- and long-term load forecast data and hydropower peak-shaving capacity data; wherein the hydropower peak-shaving capacity data is set to the installed capacity of the hydropower station, or is set separately in different time periods according to the actual output capacity; wherein the installed capacity of the hydropower station is a constant.

3. According to claim 2, a method for medium- and long-term peak load regulation of hydropower considering time period contribution is characterized in that: The load demarcation point extraction in S2 is to propose the basic judgment conditions of the load characteristic change point based on the load amplitude and fluctuation quantitative index, and extract it; Specifically, the load extreme value points have clear peak and valley physical meanings, including load characteristic changes, and the load sequence extreme value points are selected as the initial characteristic sequence: Where t is the cutoff point, n is the total number of cutoff points, and l is the extreme value of the load sequence at the corresponding cutoff point.

4. According to claim 2, a method for medium- and long-term peak load regulation of hydropower considering time period contribution is characterized in that: The demarcation point screening in S3 is to retain only the demarcation points with load trend turning significance according to the peak regulation capacity of the hydropower station, and filter out the demarcation interference caused by small fluctuations in the load curve; The full cycle segmentation in S4 is to segment the original load into time segments according to the reserved landmark points to obtain multiple scheduling periods; Specifically, based on the frequent medium- and long-term load fluctuations and the large number of sequence data points obtained in step S2, some data points are only generated by small medium- and long-term load fluctuations and do not have the significance of a load trend turning point. A load sequence smoothing strategy is used to superimpose a hydropower station peak-shaving capacity screening strategy to screen out the final dividing point and divide the scheduling period into a set of continuous time periods by the dividing point.

5. According to claim 4, a method for medium- and long-term peak load regulation of hydropower considering time period contribution is characterized in that: The load sequence smoothing strategy is specifically as follows: First, define the load amplitude characteristic as the amplitude ratio A, and the fluctuation characteristic as the minimum time interval R of the extreme points. If the amplitude ratio is less than A and the time interval is less than R, then it is eliminated and from Continue to judge, as shown in formula (1): Where t is the dividing point, i is one of the dividing points, A is the amplitude ratio, R is the minimum time interval of the extreme point, l is the extreme value of the load sequence at the corresponding dividing point, p is the output of the hydropower station at the dividing point, and Δt is the time interval.

6. According to claim 5, a method for medium- and long-term peak load regulation of hydropower considering time period contribution is characterized in that: The peak load capacity screening strategy of the hydropower station is specifically as follows: The left and right sides of the dividing point belong to different time periods. In order to ensure the consistency of the output of the hydropower station in different sections around the dividing point, the heuristic load shedding process is considered. The working position of the hydropower station in different time periods is jointly determined by the load peak value and the hydropower peak regulation capacity during the scheduling period. When the dividing point belongs to the time period below the working position of the hydropower station, the output of the hydropower station is the minimum output. Only the dividing point in this period is retained to meet the consistency of the output of the dividing point, as shown in formula (2): Where P t - is the power output of the hydropower station calculated in the period to the left of the demarcation point t, P t + It is the power output of the hydropower station calculated in the period to the right of the dividing point t.

7. According to claim 6, a method for medium- and long-term peak load regulation of hydropower considering the contribution of time periods, characterized in that: Calculate the allowable range of water levels at the end of different scheduling periods: According to the operation constraints of the power station, the maximum allowable water level and the minimum operable water level at the end of different time periods are recursively calculated forward and backward to form the water level range at the end of this period.

8. According to claim 7, a method for medium- and long-term peak load regulation of hydropower considering the contribution of time periods is characterized in that: Setting the time period contribution in S5 is the dispatcher setting the hydropower peak-shaving capacity for each dispatch period after segmentation, so as to achieve targeted allocation of hydropower peak-shaving capacity within the dispatch period; Specifically, it includes: setting the peak load regulation capacity of hydropower in different periods, as shown in formula (3), P n peak is the peak load regulation capacity of the hydropower station in segment n, P n min is the minimum output of the hydropower station in segment n, P n max is the maximum output of the hydropower station in segment n, λ is the contribution degree of the period, which can be set manually. The larger λ is, the greater the peak regulation depth of segment n is; P n peak =P n min +λ·(P n max -P n min ) (3)。 9. A method for medium- and long-term peak load regulation of hydropower considering time period contribution according to claim 8, characterized in that: The load shedding in step S6 is to use the load shedding method in different sections according to the peak load regulation capacity of the hydropower in the section, and solve the hydropower operation process in the section; Specifically, it includes: independently using a heuristic load shedding method for different sections. After the first load shedding in each section, the final water level of the period is calculated to check whether it is within the allowable range of the final water level. If it is lower than the lower limit, λ is reduced until the final water level of the period meets the lower limit requirement; if the water level is higher than the allowable upper limit, λ is increased until the final water level of the period meets the upper limit requirement. The calculation is performed section by section until the hydropower output plan for different periods in the entire scheduling cycle is obtained.

10. A method for medium- and long-term peak load regulation of hydropower considering time period contribution according to claim 8, characterized in that: The detailed steps of load cutoff point extraction and cutoff point screening are as follows: Step 1. Extract the extreme points of the load sequence and generate the extreme sequence L′; Step 2. Set the current time t = 0, define the load amplitude characteristic as the amplitude ratio A, and the fluctuation characteristic as the minimum time interval R of the extreme value point. If two adjacent points in the extreme value sequence If the amplitude ratio is less than L and the time interval is less than R, then it is eliminated and from Continue to judge, as shown in formula (4), and get the preliminary demarcation point sequence L s ; Step 3. In L s Based on this, the maximum value points are eliminated to obtain the boundary sequence L' that needs to be screened for consistency s ={(t s,1 ,l s,1 ),(t s,2 ,l s,2 ),...,(t s,n ,l s,n )}, the scheduling period is t s,1 ,t s,2 ,...,t s,n The entire dispatching period is divided into sections as the demarcation point, and the installed capacity of the hydropower station is used as the peak-shaving capacity of each period. s,1 ,t s,2 ,...,t s,n Verify whether the hydropower station meets the output consistency at this moment, as shown in formula (5); traverse L' s All time points in the equation (5) are eliminated if they do not satisfy the equation (5). Finally, the boundary sequence L is obtained. se ={(t se,1 ,l se,1 ),(t se,2 ,l se,2 ),...,(t se,I ,l s,I )}; Step 4. Set the number of sub-periods i = 0, and calculate the allowable range of water levels at the end of different scheduling periods: According to the operating constraints such as power station output, water level, flow, etc., the maximum allowable water level and the minimum operable water level at the end of different periods are recursively calculated in the forward and reverse directions to form the water level range at the end of this period Step 5. Set the time period contribution: Set the time period contribution λ of sub-period i i , calculate the peak load regulation capacity of hydropower during this period, as shown in the following formula: P i peak =P i min +λ i ·(P i max -P i min ) (6) Step 6. Variable scale load shedding: Adopt heuristic load shedding method, according to P i peak Determine the working position of the hydropower station, calculate the output during the period, and then calculate the final water level of the period to check whether it is within the allowable range of the final water level. If it is below the lower limit, reduce λ i Until the water level at the end of the period meets the lower limit requirement; if the water level is higher than the upper limit allowed, increase λ until the water level at the end of the period meets the upper limit requirement; Step 7. Determine whether i=I. If so, the calculation ends. If not, set i=i+1 and repeat Step 4-Step 6 until the condition is met.

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