A joint operation dispatching method for multi-energy system based on horizontal pumped storage

Abstract

The present invention relates to a method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage. The method transforms the adjustable hydropower that meets the conditions in the multi-energy system into horizontal pumped storage, and optimizes the dispatching modeling and efficiently solves the multi-energy system. The method can effectively improve the regulation capacity of the adjustable hydropower, smooth the volatility and randomness of wind power and photovoltaics, achieve seasonal complementarity of wind power, photovoltaics and hydropower, and improve the utilization efficiency of clean energy such as wind and solar power, thereby solving the contradiction between supply and demand of the power system, maximizing the power generation efficiency and peak regulation efficiency, and facilitating the safe and economical operation of the multi-energy system.

Description

Technical Field

[0001] The present invention relates to the technical field of power system engineering, and in particular to a multi-energy system joint operation dispatching method based on horizontal pumped storage. Background Art

[0002] In recent years, renewable energy generation such as wind power and photovoltaic power has gradually become an important area of ​​transformation of the power system. However, with the large-scale grid connection of wind power and photovoltaic power, the power system faces the challenges of strong randomness and violent fluctuations in the output of the power generation side due to the large fluctuations in wind and solar power output, insufficient regulation capacity of conventional hydropower, low regulation efficiency of energy storage systems, and the complexity of the joint operation of multi-energy systems. This has led to a significant reduction in the stability and reliability of the system, and the inability to fully utilize wind and solar resources. Although the existing technology can improve the stability of the system to a certain extent through the complementary characteristics of multiple energy sources, the effect is not ideal. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a multi-energy system joint operation scheduling method based on horizontal pumped storage, which can effectively improve the operation stability and reliability of the multi-energy system and the resource utilization efficiency.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: a multi-energy system joint operation scheduling method based on horizontal pumped storage, the multi-energy system includes a wind farm, a photovoltaic power station, a thermal power plant, a hydropower station and an energy storage power station, wherein the hydropower station includes an adjustable hydropower station and a non-adjustable hydropower station, wherein a pumping station is arranged for an adjustable hydropower station that meets the set conditions to obtain a horizontal pumped storage power station, and the scheduling method includes the following steps:

[0005] S1, build an optimization scheduling model, where the objective function is as follows:

[0006]

[0007] In the above formula, F obj represents the objective function value, t represents the tth scheduling period, T represents the total number of scheduling periods in the scheduling period, and T is a natural number greater than or equal to 1. represents the power load of the power system in the tth dispatching period, represents the output of the mth wind farm in the tth dispatch period, M represents the number of wind farms, represents the output of the k-th photovoltaic power station in the t-th period, K represents the number of photovoltaic power stations, represents the output of the sth thermal power plant in the tth period, S represents the number of thermal power plants, represents the output of the rth hydropower station in the tth period, R represents the number of hydropower stations, that is, the sum of the number of adjustable hydropower stations and non-adjustable hydropower stations, represents the output of the lth energy storage power station in the tth period, L represents the number of energy storage power stations, C represents the translation constant, and M, K, S, R, and L are all natural numbers greater than or equal to 1;

[0008] S2, according to the installed capacity and output characteristic curve of wind farms and photovoltaic power stations, calculate the output of wind farms and photovoltaic power stations in each dispatching period; according to the output characteristic curve of thermal power plants and non-adjustable hydropower stations, calculate the output of thermal power plants and non-adjustable hydropower stations in each dispatching period;

[0009] S3, subtracting the output of the wind farm, photovoltaic power station, thermal power plant and non-adjustable hydropower station during the dispatch period from the power system power load curve during the dispatch period to obtain a first residual power load curve;

[0010] S4, according to the initial water level and the final water level of the adjustable hydropower station during the scheduling period, the initial water level at each time point in the scheduling period is obtained by linear interpolation, and the initial output process of the adjustable hydropower station is calculated according to the water inflow data, and the average total output of the adjustable hydropower station during the scheduling period is calculated based on the initial output process of the adjustable hydropower station, and the output difference is obtained by subtracting the minimum value of the first residual power load curve from the average total output of the adjustable hydropower station during the scheduling period;

[0011] S5, calling the objective function, if the output difference is a positive value, assigning the output difference to the translation coefficient C in the objective function, otherwise the translation coefficient C is 0, and the first remaining power load curve is translated by C along the load direction to obtain the second remaining power load curve, and let Then, the stepwise optimization algorithm is used to solve the optimal output process of each adjustable hydropower station during the dispatch period.

[0012] S6, subtracting the optimal output of the adjustable hydropower station from the second remaining power load curve to obtain a third remaining power load curve, and then calculating an average value of the third remaining power load curve;

[0013] S7, according to the initial storage power and the final storage power of the energy storage power station, the initial solution of the energy storage power at each time point in the scheduling period is obtained by linear interpolation, the objective function is called, and the inverse of the average value of the third remaining power load curve is assigned to the translation coefficient C in the objective function, so as to translate the third remaining power load curve along the load direction by C, wherein the output of the adjustable hydropower station in the hydropower station in the objective function adopts the optimal output of the adjustable hydropower station obtained in step S5, and then the optimal output process of the energy storage power station is solved by a stepwise optimization algorithm in each time period;

[0014] S8, according to the power load curve of the power system during the dispatching period and the output process of various power stations in the multi-energy system, calculate the power load gap in each dispatching period, and then determine the external power purchase plan.

[0015] Furthermore, the constraints in the optimization scheduling model include:

[0016] I rt =Q (r-1)t +B rt

[0017]

[0018] Z r,min ≤Z rt ≤Z r,max

[0019] Q r,min ≤Q rt ≤Q r,max

[0020] V r(t+1) =V rt +[I rt -Q rt ]△t

[0021] Z r0 =Z r begin , Z rT =Z r end

[0022]

[0023] V p,min ≤V pt ≤V p,max

[0024] Among them, I rt and B rt They represent the total inflow and interval runoff of the rth hydropower station in the tth dispatching period, Q rt represents the discharge flow of the rth hydropower station in the tth period, represents the output of the mth wind farm in the tth dispatch period, represents the maximum output of the mth wind farm, represents the output of the k-th PV power station in the t-th scheduling period, represents the maximum output of the kth photovoltaic power station, Z rt represents the operating water level of the rth hydropower station in the tth dispatching period, Z r,min , Z r,max They represent the minimum and maximum operating water levels of the rth hydropower station, Q r,min , Q r,max They represent the minimum and maximum discharge flows of the rth hydropower station, respectively. When the hydropower station is a horizontal pumped storage power station, Q r,min The value is -Q pump , Q pump represents the maximum pumping flow of the pumping station of the horizontal pumped storage power station, otherwise Qr,min The value of V is greater than or equal to 0. rt represents the water storage capacity of the rth hydropower station in the tth dispatching period, Z r begin , Z r end They represent the initial water level and final water level of the rth hydropower station dispatch period, represents the output of the sth thermal power plant in the tth dispatch period, They represent the minimum and maximum output of the sth thermal power plant, respectively. denote the minimum and maximum output of the rth hydropower station, respectively. represents the output of the rth hydropower station in the tth dispatching period, V pt represents the water storage capacity of the lower tank of the horizontal pumped storage power station in the tth dispatching period, V p,min 、V p,max They respectively represent the minimum and maximum water storage capacity of the lower tank of a horizontal pumped-storage power station.

[0025] Furthermore, the arrangement of the pumping station for the adjustable hydropower satisfying the set conditions obtains a horizontal pumped-storage power station, wherein the set conditions include: the tailwater level of the adjustable hydropower station is connected with the normal water level of the downstream adjacent hydropower station; the adjustable hydropower station has a regulating storage capacity above daily regulation; the net water head of the adjustable hydropower station is greater than or equal to 30m; and there are site conditions for installing the pumping station.

[0026] Furthermore, the adjustable hydropower station that meets the set conditions is arranged to obtain a horizontal pumped storage power station, wherein the number of pumps in the pumping station is determined as follows:

[0027] Calculate the rated total pumping power P of the pumping station: P = 9.81*(3.65VH) / (3.6ηh);

[0028] Calculate the number of water pumps Y: Y = P / p;

[0029] In the above formula, V represents the maximum regulating storage capacity of the horizontal pumped storage power station, H represents the rated pumping head, h represents the annual equivalent pumping hours of the horizontal pumped storage power station, η represents the designed pumping efficiency of the pump, and p represents the rated power of the pump.

[0030] Furthermore, the stepwise optimization algorithm is used to solve the optimal output process of the adjustable hydropower station in each period, specifically including:

[0031] S51, select the jth adjustable hydropower station at the most upstream, j is a natural number greater than or equal to 1, and the initial value of j is 1, then according to the initial water level of each dispatching period of the jth adjustable hydropower station obtained in step S4, fix the water level at time t0 and time t2 to remain unchanged, discretize the initial water level at time t1, where t1=t0+△t, t2=t0+2*△t, △t represents the duration of each dispatching period, the initial value of t0 is 0, where time t0 to time t1 is the tth dispatching period, time t1 to time t2 is the t+1th dispatching period, t is a natural number greater than or equal to 1, calculate the output and discharge flow of the tth dispatching period and the t+1th dispatching period under different discrete water levels;

[0032] S52, according to the discharge flow of the j-th adjustable hydropower station and the interval runoff of each downstream adjustable hydropower station, while keeping the operating water level of each adjustable hydropower station downstream of the j-th adjustable hydropower station unchanged, calculate the output of each downstream adjustable hydropower station in the t-th scheduling period and the t+1-th scheduling period, add the output of the j-th adjustable hydropower station and all the adjustable water stations downstream of it in the t-th period and the t+1-th period to the optimal output of the j-1-th adjustable hydropower station to obtain the total adjustable hydropower output in the t-th scheduling period and the t+1-th scheduling period, wherein when j=1, the optimal output of the j-1-th adjustable hydropower station is set to 0, substitute the total adjustable hydropower output corresponding to the discrete water level at time t1 into the objective function called in step S5, and select the discrete water level corresponding to the minimum objective function value as the optimal water level of the j-th adjustable hydropower station at time t1;

[0033] S53, determine whether t2 reaches the end of the dispatch period. If not, execute t0=t0+△t and return to execute S51. If yes, calculate the optimal output process of each dispatch period within the dispatch period of the jth adjustable hydropower station according to the optimal water level at each time point of the jth adjustable hydropower station;

[0034] S54, determine whether there is another adjustable hydropower station downstream of the jth adjustable hydropower station. If so, execute j=j+1 and return to execute S51. If not, output the optimal output process of each adjustable hydropower station in each scheduling period during the scheduling period.

[0035] Furthermore, the specific method of discretizing the initial water level at time t1 is:

[0036] There are a number of discrete water levels above and below the initial water level at time t1, a total of 2a discrete water levels, of which the nth discrete water level from low to high is calculated by the following formula:

[0037] Z n，jt1 =f -1 (V n，jt1 )

[0038] V n，jt1 =Vjt1 +(na)*0.95 |n-a| *ΔQ*Δt

[0039] In the above formula, Z n，jt1 represents the nth discrete water level of the initial water level of the jth adjustable hydropower station at time t1, f -1 is the inverse function of the water level and storage capacity of the hydropower station, a is a natural number greater than or equal to 1, n is a natural number greater than or equal to 1 and less than or equal to 2a, V n，jt1 V represents the nth discrete water storage capacity of the jth adjustable hydropower station at time t1, jt1 represents the water storage capacity of the jth adjustable hydropower station at time t1, ΔQ represents the preset discrete step length of flow, and Δt represents the step length of the scheduling period.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] The method of the present invention can bring the following technical effects by transforming the adjustable hydropower station into a horizontal pumped-storage power station, and optimizing the scheduling modeling and efficiently solving the multi-energy system: 1. By transforming the adjustable hydropower station into a horizontal pumped-storage power station, the output regulation range of the adjustable hydropower station is expanded, the regulation capacity of the adjustable hydropower is improved, and the problems of hydropower abandonment and peak regulation in the flood season and insufficient output in the dry season can be effectively alleviated, and the regulating role of hydropower in the power system is enhanced; 2. The efficiency of resource utilization is improved. Through the joint optimization scheduling of wind, solar, water and storage for horizontal pumped storage, the supply and demand imbalance caused by the drastic fluctuations in wind and solar output and the abandonment of wind and solar power can be effectively solved, so that wind and solar resources can be fully utilized; 3. The safe and economical operation of the multi-energy system is realized. Through the joint optimization scheduling of wind, solar, water, fire and storage, the volatility and randomness of wind power and photovoltaic power are smoothed, the seasonal complementarity of wind power, photovoltaic power and hydropower is realized, and the supply and demand contradiction of the multi-energy system is solved, thereby maximizing the power generation efficiency and peak regulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a typical daily power grid load and system output diagram in summer under the current status of the study area.

[0043] Figure 2 These are typical daily load curves in summer and winter in the study area.

[0044] Figure 3 It is the typical daily output characteristic curve of wind and solar power generation in summer and winter.

[0045] Figure 4 It is the average daily inflow into one of the cascade hydropower stations in the study area.

[0046] Figure 5The diagram is a typical day power grid load and system output diagram in summer after the optimization scheduling is performed using the method of the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the embodiments of the drawings, examples of which are shown in the drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0048] In the description of the present application, it should be noted that for directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions and positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific protection scope of the present application. The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0049] The present invention relates to a method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage. The multi-energy system comprises a wind farm, a photovoltaic power station, a thermal power plant, a hydropower station and an energy storage power station, wherein the thermal power plant comprises a garbage power plant, and the hydropower station comprises an adjustable hydropower station and a non-adjustable hydropower station. The non-adjustable hydropower station can also be called small hydropower or runoff hydropower. A pumping station is arranged for an adjustable hydropower station that meets set conditions to obtain a pumped storage power station. Generally speaking, the adjustable hydropower station in a multi-energy system is a group of cascade hydropower stations. When carrying out the transformation of a horizontal pumped-storage power station, factors such as the regulating reservoir capacity and power generation head of the adjustable hydropower station need to be considered, that is, the aforementioned setting conditions need to be met. The setting conditions are as follows: there is a tailwater connection between the tailwater level of the adjustable hydropower station and the normal water storage level of the downstream adjacent hydropower station. Whether there is a tailwater connection in practice can be obtained through empirical observation; the adjustable hydropower station has a regulating reservoir capacity above daily regulation, and it is even better when it has a seasonal regulation reservoir capacity; the net water head of the adjustable hydropower station is greater than or equal to 30m, and the higher the net water head, the better; there are site conditions for installing a pumping station. As a technical personnel in this field, after knowing that a pumping station is to be installed, you should know the relevant site requirements such as site width and geological conditions, which are not described in detail here.

[0050] In this embodiment, the number of pumps in the pumping station of the pumped storage power station is determined as follows:

[0051] Calculate the rated total pumping power P of the pumping station: P = 9.81*(3.65VH) / (3.6ηh);

[0052] Calculate the number of water pumps Y: Y = P / p;

[0053] In the above formula, V represents the maximum regulating storage capacity of horizontal pumped storage. The maximum regulating storage capacity can be determined through empirical comparison based on the regulating capacity of the adjustable hydropower station and the principle of having little impact on the normal operation of the hydropower station. H represents the rated pumping head, h represents the annual equivalent pumping hours of the horizontal pumped storage power station. In practice, the peak and valley characteristics of electricity load and other forms of pumped storage power stations can be comprehensively considered to determine the annual equivalent pumping hours of the horizontal pumped storage power station based on experience and scientific selection. η represents the designed pumping efficiency of the pump, and p represents the rated power of the pump.

[0054] When scheduling the above-mentioned multi-energy system, for a given load curve, after determining the installed capacity of wind power, photovoltaic power and energy storage capacity, it is necessary to reasonably arrange the output of adjustable hydropower and energy storage power stations so that the total output of the multi-energy system in each scheduling period can meet the load demand as much as possible. That is, it is required that the total output curve of the multi-energy system in each scheduling period is as parallel to the load curve as possible to achieve the best peak regulation. At the same time, it is required that the position of the total output curve of the multi-energy system in each scheduling period is as high as possible to achieve the maximum output, that is, the sum of the squares of the difference between the total output of the system in each scheduling period and the shifted electricity load curve is minimized.

[0055] Specifically, the multi-energy system joint operation scheduling method based on horizontal pumped storage of the present application includes the following steps:

[0056] S1, build an optimization scheduling model, where the objective function is as follows:

[0057]

[0058] In the above formula, F obj represents the objective function value, t represents the tth scheduling period, T represents the total number of scheduling periods in the scheduling period, T is a natural number greater than or equal to 1, and scheduling is generally performed on a daily scale, that is, the scheduling period is one day, and the T value is usually 24, 48 or 96. represents the power load of the power system in the tth dispatching period, represents the output of the mth wind farm in the tth dispatch period, M represents the number of wind farms, represents the output of the k-th photovoltaic power station in the t-th period, K represents the number of photovoltaic power stations, represents the output of the sth thermal power plant in the tth period, S represents the number of thermal power plants, represents the output of the rth hydropower station in the tth period, R represents the number of hydropower stations, that is, the sum of the number of adjustable hydropower stations and non-adjustable hydropower stations, represents the output of the lth energy storage power station in the tth period, L represents the number of energy storage power stations, C represents the translation constant, and M, K, S, R, and L are all natural numbers greater than or equal to 1;

[0059] S2, based on the known installed capacity and output characteristic curves of wind farms and photovoltaic power stations, calculate the output of wind farms and photovoltaic power stations in each dispatching period; based on the known output characteristic curves of thermal power plants and non-adjustable hydropower stations, calculate the output of thermal power plants and non-adjustable hydropower stations in each dispatching period;

[0060] S3, subtracting the output of the wind farm, photovoltaic power station, thermal power plant and non-adjustable hydropower station during the dispatch period from the power system power load curve during the given dispatch period to obtain a first residual power load curve;

[0061] S4, according to the initial water level and the final water level of the adjustable hydropower station during the scheduling period, the initial water level at each time point in the scheduling period is obtained by linear interpolation, and the initial output process of the adjustable hydropower station is calculated according to the known water inflow data, and the average total output of the adjustable hydropower station during the scheduling period is calculated based on the initial output process of the adjustable hydropower station, and the output difference is obtained by subtracting the minimum value of the first residual power load curve from the average total output of the adjustable hydropower station during the scheduling period;

[0062] S5, calling the objective function, if the output difference is a positive value, assigning the output difference to the translation coefficient C in the objective function, otherwise the translation coefficient C is 0, and the first remaining power load curve is translated by C along the load direction to obtain the second remaining power load curve, and let Then, the stepwise optimization algorithm is used to solve the optimal output process of each adjustable hydropower station during the dispatch period, and the stepwise optimization algorithm can also be called POA algorithm.

[0063] S6, subtracting the optimal output of the adjustable hydropower station from the second remaining power load curve to obtain a third remaining power load curve, and then calculating an average value of the third remaining power load curve;

[0064] S7, according to the initial storage power and the final storage power of the energy storage power station, the initial solution of the energy storage power at each time point in the scheduling period is obtained by linear interpolation, the objective function is called, and the inverse of the average value of the third remaining power load curve is assigned to the translation coefficient C in the objective function, so as to translate the third remaining power load curve along the load direction by C, wherein the output of the adjustable hydropower station in the hydropower station in the objective function adopts the optimal output of the adjustable hydropower station obtained in step S5, and then the optimal output process of the energy storage power station is solved by a stepwise optimization algorithm in each time period;

[0065] S8, according to the power load curve of the power system during the dispatch period and the output process of various power stations in the multi-energy system, calculate the power load gap in each dispatch period, and then determine the external power purchase plan. When the purchase amount is negative, it means external power sale.

[0066] In this embodiment, the constraints in the above optimization scheduling model include:

[0067] I rt =Q (r-1)t +B rt

[0068]

[0069] Z r,min ≤Z rt ≤Z r,max

[0070] Q r,min ≤Q rt ≤Q r,max

[0071] V r(t+1) =V rt +[I rt -Q rt ]△t

[0072] Z r0 =Z r begin , Z rT =Z r end

[0073]

[0074] V p,min ≤V pt ≤V p,max

[0075] Among them, I rt and B rt They represent the total inflow and interval runoff of the rth hydropower station in the tth dispatching period, Q rt represents the discharge flow of the rth hydropower station in the tth period, represents the output of the mth wind farm in the tth dispatch period, represents the maximum output of the mth wind farm, represents the output of the k-th PV power station in the t-th scheduling period, represents the maximum output of the kth photovoltaic power station, Z rt represents the operating water level of the rth hydropower station in the tth dispatching period, Z r,min , Z r,maxThey represent the minimum and maximum operating water levels of the rth hydropower station, Q r,min , Q r,max They represent the minimum and maximum discharge flows of the rth hydropower station, respectively. When the hydropower station is a horizontal pumped storage power station, Q r,min The value is -Q pump , Q pump represents the maximum pumping flow of the pumping station of the horizontal pumped storage power station, otherwise Q r,min The value of V is greater than or equal to 0. rt represents the water storage capacity of the rth hydropower station in the tth dispatching period, Z r begin , Z r end They represent the initial water level and the preset final water level of the rth hydropower station dispatch period, represents the output of the sth thermal power plant in the tth dispatch period, They represent the minimum and maximum output of the sth thermal power plant, respectively. denote the minimum and maximum output of the rth hydropower station, respectively. represents the output of the rth hydropower station in the tth dispatching period, V pt represents the water storage capacity of the lower tank of the horizontal pumped storage power station in the tth dispatching period, V p,min 、V p,max They represent the minimum and maximum water storage capacity of the lower tank of the horizontal pumped storage power station. It should be noted that the above parameters such as interval runoff and boundary range are all known parameters and can be obtained according to the design reports and dispatching regulations of each power station.

[0076] In this embodiment, the above-mentioned step-by-step optimization algorithm is used to solve the optimal output process of the adjustable hydropower station in each period, which specifically includes:

[0077] S51, select the jth adjustable hydropower station at the most upstream, j is a natural number greater than or equal to 1, and the initial value of j is 1, then according to the initial water level of each dispatching period of the jth adjustable hydropower station obtained in step S4, the water level at time t0 and time t2 is fixed unchanged, and the initial water level at time t1 is discretized within a set interval, wherein t1=t0+△t, t2=t0+2*△t, △t represents the duration of each dispatching period, the initial value of t0 is 0, wherein t0 to t1 is the tth dispatching period, t1 to t2 is the t+1th dispatching period, t is a natural number greater than or equal to 1, and calculate the output and discharge flow of the tth dispatching period and the t+1th dispatching period under different discrete water levels;

[0078] S52, according to the discharge flow of the j-th adjustable hydropower station and the interval runoff of each downstream adjustable hydropower station, while keeping the operating water level of each adjustable hydropower station downstream of the j-th adjustable hydropower station unchanged, calculate the output of each downstream adjustable hydropower station in the t-th scheduling period and the t+1-th scheduling period, add the output of the j-th adjustable hydropower station and all the adjustable water stations downstream of it in the t-th period and the t+1-th period to the optimal output of the j-1-th adjustable hydropower station to obtain the total adjustable hydropower output in the t-th scheduling period and the t+1-th scheduling period, wherein when j=1, the optimal output of the j-1-th adjustable hydropower station is set to 0, substitute the total adjustable hydropower output corresponding to the discrete water level at time t1 into the objective function called in step S5, and select the discrete water level corresponding to the minimum objective function value as the optimal water level of the j-th adjustable hydropower station at time t1;

[0079] S53, determine whether t2 reaches the end of the dispatch period. If not, execute t0=t0+△t and return to execute S51. If yes, calculate the optimal output process of each dispatch period within the dispatch period of the jth adjustable hydropower station according to the optimal water level at each time point of the jth adjustable hydropower station;

[0080] S54, determine whether there is another adjustable hydropower station downstream of the jth adjustable hydropower station. If so, execute j=j+1 and return to execute S51. If not, output the optimal output process of each adjustable hydropower station in each scheduling period during the scheduling period.

[0081] After knowing the calculation method of using a step-by-step optimization algorithm to solve the optimal output process of an adjustable hydropower station in each period, technical personnel in this field should be clear about the calculation process of using a step-by-step optimization algorithm to solve the optimal output process of an energy storage power station in each period, so it will not be described in detail here.

[0082] In this embodiment, the specific method of discretizing the initial water level at time t1 is as follows:

[0083] There are a number of discrete water levels above and below the initial water level at time t1, a total of 2a discrete water levels, of which the nth discrete water level from low to high is calculated by the following formula:

[0084] Z n，jt1 =f -1 (V n，jt1 )

[0085] V n，jt1 =V jt1 +(na)*0.95 |n-a| *ΔQ*Δt

[0086] In the above formula, Z n，jt1 represents the nth discrete water level of the initial water level of the jth adjustable hydropower station at time t1, f -1is the inverse function of the water level and storage capacity of the hydropower station, a is a natural number greater than or equal to 1, and in this embodiment, the value of a can be 20, n is a natural number greater than or equal to 1 and less than or equal to 2a, V n，jt1 represents the nth discrete water demand of the jth adjustable hydropower station at time t1, V jt1 represents the water storage capacity of the jth adjustable hydropower station at time t1, ΔQ represents the preset flow discrete step length, which can be 5 in this embodiment, and Δt represents the scheduling time step. That is, in the discretization process, the adjacent discrete points are not equidistant. As the discrete points gradually move away from the initial water level, the distance between the discrete points decays by 0.95 times. Of course, the attenuation coefficient of 0.95 can be adjusted according to different actual conditions, which can improve the final optimization accuracy.

[0087] The method of the present invention is further explained below by taking a certain research area as an example. The multi-energy system in this area includes: four adjustable hydropower stations with installed capacities of 4×20MW, 3×21MW, 3×16.5MW, and 3×30MW respectively; a wind farm with an installed capacity of 540MW; a photovoltaic power station with a total installed capacity of 945MW; 46 non-adjustable hydropower stations, i.e. small runoff hydropower stations, with a total installed capacity of 127MW; a thermal power plant, i.e. garbage power generation of 7.5MW; and a chemical energy storage power station of 318MWh. The parameters of the four adjustable hydropower stations are shown in Table 1.

[0088] Table 14 Main parameters of adjustable hydropower stations

[0089]

[0090]

[0091] In order to improve the regulation capacity of the system, the horizontal pumped storage system of Hydropower Station 2 was transformed into a horizontal pumped storage system, two pumps with a rated power of 45MW were added, and the 4 million m 3 The regulating reservoir capacity is divided into the lower pumped storage tank to form a horizontal pumped storage power station with the following parameters: regulating reservoir capacity 4 million m 3 , rated pumping flow 340m 3 / s, rated head 24m, rated pumping power 90MW, annual pumping hours 1193h, the dead water level and normal operating water level of Hydropower 3 were adjusted to 70.5m and 71.5m respectively.

[0092] The system output and power load results of a typical summer day before the regional multi-energy system integration transformation are as follows: Figure 1As shown in the figure, we can see that in the current level before the transformation, the system only used 4 adjustable hydropower and runoff small hydropower to regulate the system. The operation and output process of the 4 adjustable hydropower stations generally tracked the power load process. After regulation by the 4 adjustable hydropower stations, the peak-to-valley difference of the power load of the power grid on a typical day in summer was 111.66MW, the standard deviation of the load curve was 30.91MW, and the average power supply gap was still 285.10MW.

[0093] In the current year, the typical load curve in summer is the load curve of 2021-07-27, the maximum load day in 2021, and the typical load curve in winter is the load curve of 2021-01-07, when the peak-to-valley difference and maximum load are both large. The corresponding typical load curves are as follows: Figure 2 As shown by Figure 2 It can be seen that the power load is relatively low from 2 to 8 in the morning in summer, reaching the lowest at 7, with obvious fluctuations during this period, and then steadily increasing with small fluctuations, with the maximum load being 790MW and the minimum being 480MW. In winter, except for the relatively stable power load from 2 to 8 without obvious fluctuations, the load fluctuates greatly at other times.

[0094] The output characteristics analysis is carried out below.

[0095] Analysis of wind and solar power output characteristics: In summer, wind power output is relatively small, with an average daily equivalent hours of only 3.15 hours, while in winter, wind power output is relatively large, with an average daily equivalent hours of 13 hours. Figure 3 As shown, in summer, the wind power output is relatively small, and the output coefficient is generally below 0.2MW. It is a season with small power generation. The intraday fluctuation is relatively stable, and the output at each time is almost the same. In winter, the output coefficient is maintained at around 0.5MW, gradually decreasing from a maximum of 0.6MW at 0:00 to 0.4MW at 8:00, and then gradually recovering to around 0.5MW during the day. It is a season with large power generation.

[0096] The maximum monthly average irradiation in the study area occurs in July, with an average daily equivalent power generation hour of 5.28h, and a typical daily photovoltaic output curve in summer is obtained; the minimum monthly average irradiation occurs in January and February, with an average daily equivalent power generation hour of 2.39h. In summer, the light amplitude is strong and the irradiation time is long, so the photovoltaic output is relatively large; in winter, the light amplitude decreases, and the irradiation time also decreases, so the photovoltaic output also decreases accordingly. The photovoltaic output in winter is generally below 0.4MW, which is a season with relatively low output in the year; the photovoltaic output in summer is generally above 0.5MW, which is a relatively large season in the year.

[0097] Analysis of the output characteristics of small hydropower, thermal power and energy storage power stations: The total installed capacity of small hydropower in the grid is 127MW in the current level year, and the total installed capacity of small hydropower in the planned level year is 132MW. The output of small hydropower in a typical day is set to remain unchanged, the typical daily load rate in summer is 0.8, and the typical daily load rate in winter is 0.3. The output in the corresponding period is the installed capacity multiplied by the load rate. There is only one 7.5MW garbage power station with thermal power installed in the grid in the study area, so the installed capacity of thermal power in the current and planned level years is only 7.5MW. The output on a typical day remains unchanged, and the typical daily load rate in summer and winter is 0.6.

[0098] The energy storage power station in this study is an electrochemical energy storage power station with a charging and discharging efficiency of 95%, a maximum charging and discharging depth of 5% to 95%, and a rated power charging and discharging hours of 2h. The current and planned annual energy storage installed capacity is determined based on the optimization configuration results, and the initial and final storage capacity is determined in combination with the energy storage installed capacity.

[0099] Adjustable hydropower parameters and runoff characteristics analysis: Based on the daily runoff data from 2015 to 2022, the average daily runoff of cascade hydropower stations over the past 10 years is obtained. Figure 4 As shown by Figure 4 It can be seen that the flow of hydropower is closely related to seasonal changes. In spring and summer, there will be more rainfall and abundant water. Usually, the water is most abundant in June, with a flow of 1050m 3 / s, and then gradually decreases over time. In autumn and winter, rainfall decreases and river water levels drop, reaching a minimum of only 200m in December. 3 / s or so.

[0100] Based on the installed capacity of the power grid at the end of 2022 and the above-mentioned optimization configuration results, in the current level year, the power grid has 4 direct-adjusted power sources with daily adjustment capacity of 282.5MW hydropower stations, 127MW small hydropower, 544MW wind power, 911MW photovoltaic, 7.5MW waste power generation, and 318MWh chemical energy storage. At the same time, a 90MW pumping station is installed for one of the adjustable hydropower integration transformations. Combined with the current level year load curve, the current level year dispatch simulation is carried out as follows: Figure 5 As shown by Figure 5 The results show that under the current situation, the power grid can meet the power load demand of the system well during the day by integrating conventional hydropower and transforming 90MW pumping stations. The total output of the system on a typical summer day can gradually increase the photovoltaic power generation from 6 to 13 o'clock. At noon, photovoltaic power generation alone can meet the load demand, and there is a small amount of surplus electricity. After 18:00 in the evening, the light weakens, and the photovoltaic power generation gradually decreases, resulting in the system output gradually failing to meet the power load demand. Finally, after joint operation and optimization scheduling, the average daily power supply gap of the power grid on a typical summer day is 24.63MW.

[0101] From the above analysis, it can be seen that the multi-energy system joint operation scheduling method based on horizontal pumped storage of the present invention is adopted for scheduling in the study area. The typical daily load gap of the multi-energy system in summer is only 24.63MW, which is 285.10MW compared with the load gap scheduled by the existing scheduling method. The load gap is greatly reduced, the supply and demand balance of the power system can be basically achieved, and the waste of resources of the multi-energy system is avoided.

[0102] Although embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage, characterized in that: The multi-energy system includes a wind farm, a photovoltaic power station, a thermal power plant, a hydropower station and an energy storage power station, wherein the hydropower station includes an adjustable hydropower station and a non-adjustable hydropower station, wherein a pumping station is arranged for an adjustable hydropower station that meets the set conditions to obtain a horizontal pumped storage power station, and the scheduling method includes the following steps: S1, build an optimization scheduling model, where the objective function is as follows: In the above formula, F obj represents the objective function value, t represents the tth scheduling period, T represents the total number of scheduling periods in the scheduling period, and T is a natural number greater than or equal to 1. represents the power load of the power system in the tth dispatching period, represents the output of the mth wind farm in the tth dispatch period, M represents the number of wind farms, represents the output of the k-th photovoltaic power station in the t-th period, K represents the number of photovoltaic power stations, represents the output of the sth thermal power plant in the tth period, S represents the number of thermal power plants, represents the output of the rth hydropower station in the tth period, R represents the number of hydropower stations, that is, the sum of the number of adjustable hydropower stations and non-adjustable hydropower stations, represents the output of the lth energy storage power station in the tth period, L represents the number of energy storage power stations, C represents the translation constant, and M, K, S, R, and L are all natural numbers greater than or equal to 1; S2, according to the installed capacity and output characteristic curve of wind farms and photovoltaic power stations, calculate the output of wind farms and photovoltaic power stations in each dispatching period; according to the output characteristic curve of thermal power plants and non-adjustable hydropower stations, calculate the output of thermal power plants and non-adjustable hydropower stations in each dispatching period; S3, subtracting the output of the wind farm, photovoltaic power station, thermal power plant and non-adjustable hydropower station during the dispatch period from the power system power load curve during the dispatch period to obtain a first residual power load curve; S4, according to the initial water level and the final water level of the adjustable hydropower station during the scheduling period, the initial water level at each time point in the scheduling period is obtained by linear interpolation, and the initial output process of the adjustable hydropower station is calculated according to the water inflow data, and the average total output of the adjustable hydropower station during the scheduling period is calculated based on the initial output process of the adjustable hydropower station, and the output difference is obtained by subtracting the minimum value of the first residual power load curve from the average total output of the adjustable hydropower station during the scheduling period; S5, calling the objective function, if the output difference is a positive value, assigning the output difference to the translation coefficient C in the objective function, otherwise the translation coefficient C is 0, and the first remaining power load curve is translated by C along the load direction to obtain the second remaining power load curve, and let Then, the stepwise optimization algorithm is used to solve the optimal output process of each adjustable hydropower station during the dispatch period. S6, subtracting the optimal output of the adjustable hydropower station from the second remaining power load curve to obtain a third remaining power load curve, and then calculating an average value of the third remaining power load curve; S7, according to the initial storage power and the final storage power of the energy storage power station, the initial solution of the energy storage power at each time point in the scheduling period is obtained by linear interpolation, the objective function is called, and the inverse of the average value of the third remaining power load curve is assigned to the translation coefficient C in the objective function, so as to translate the third remaining power load curve along the load direction by C, wherein the output of the adjustable hydropower station in the hydropower station in the objective function adopts the optimal output of the adjustable hydropower station obtained in step S5, and then the optimal output process of the energy storage power station is solved by a stepwise optimization algorithm in each time period; S8, according to the power load curve of the power system during the dispatching period and the output process of various power stations in the multi-energy system, calculate the power load gap in each dispatching period, and then determine the external power purchase plan.

2. A method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage according to claim 1, characterized in that: The constraints in the optimization scheduling model include: I rt =Q (r-1)t +B rt WITH r,min ≤Z rt ≤Z r,max Q r,min ≤Q rt ≤Q r,max V r(t+1) =V rt +[I rt -Q rt ]△t WITH r0 =Z rbegin ,WITH rT =Z rend In p,min ≤V pt ≤V p,max Among them, I rt and B rt They represent the total inflow and interval runoff of the rth hydropower station in the tth dispatching period, Q rt represents the discharge flow of the rth hydropower station in the tth period, represents the output of the mth wind farm in the tth dispatch period, represents the maximum output of the mth wind farm, represents the output of the k-th PV power station in the t-th scheduling period, represents the maximum output of the kth photovoltaic power station, Z rt represents the operating water level of the rth hydropower station in the tth dispatching period, Z r,min , Z r,max They represent the minimum and maximum operating water levels of the rth hydropower station, Q r,min , Q r,max They represent the minimum and maximum discharge flows of the rth hydropower station, respectively. When the hydropower station is a horizontal pumped storage power station, Q r,min The value is -Q pump , Q pump represents the maximum pumping flow of the pumping station of the horizontal pumped storage power station, otherwise Q r,min The value of V is greater than or equal to 0. rt represents the water storage capacity of the rth hydropower station in the tth dispatching period, Z rbegin , Z rend They represent the initial water level and final water level of the rth hydropower station dispatch period, represents the output of the sth thermal power plant in the tth dispatch period, They represent the minimum and maximum output of the sth thermal power plant, respectively. denote the minimum and maximum output of the rth hydropower station, respectively. represents the output of the rth hydropower station in the tth dispatching period, V pt represents the water storage capacity of the lower tank of the horizontal pumped storage power station in the tth dispatching period, V p,min 、V p,max They respectively represent the minimum and maximum water storage capacity of the lower tank of a horizontal pumped-storage power station.

3. A method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage according to claim 2, characterized in that: The horizontal pumped storage power station is obtained by arranging a pumping station for the adjustable hydropower station that meets the set conditions, wherein the set conditions include: the tail water level of the adjustable hydropower station is connected with the normal water storage level of the downstream adjacent hydropower station; the adjustable hydropower station has a regulating storage capacity of more than daily regulation; the net water head of the adjustable hydropower station is greater than or equal to 30m; and there are site conditions for installing the pumping station.

4. A method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage according to claim 3, characterized in that: The adjustable hydropower station that meets the set conditions is arranged to obtain a horizontal pumped storage power station, wherein the number of pumps in the pumping station is determined as follows: Calculate the rated total pumping power P of the pumping station: P = 9.81*(3.65VH) / (3.6ηh); Calculate the number of water pumps Y: Y = P / p; In the above formula, V represents the maximum regulating storage capacity of the horizontal pumped storage power station, H represents the rated pumping head, h represents the annual equivalent pumping hours of the horizontal pumped storage power station, η represents the designed pumping efficiency of the pump, and p represents the rated power of the pump.

5. The method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage according to claim 1, characterized in that: The process of using a step-by-step optimization algorithm to solve the optimal output of the adjustable hydropower station in each period specifically includes: S51, select the jth adjustable hydropower station at the most upstream, j is a natural number greater than or equal to 1, and the initial value of j is 1, then according to the initial water level of each dispatching period of the jth adjustable hydropower station obtained in step S4, fix the water level at time t0 and time t2 to remain unchanged, discretize the initial water level at time t1, where t1=t0+△t, t2=t0+2*△t, △t represents the duration of each dispatching period, the initial value of t0 is 0, where time t0 to time t1 is the tth dispatching period, time t1 to time t2 is the t+1th dispatching period, t is a natural number greater than or equal to 1, calculate the output and discharge flow of the tth dispatching period and the t+1th dispatching period under different discrete water levels; S52, according to the discharge flow of the j-th adjustable hydropower station and the interval runoff of each downstream adjustable hydropower station, while keeping the operating water level of each adjustable hydropower station downstream of the j-th adjustable hydropower station unchanged, calculate the output of each downstream adjustable hydropower station in the t-th scheduling period and the t+1-th scheduling period, add the output of the j-th adjustable hydropower station and all the adjustable water stations downstream of it in the t-th period and the t+1-th period to the optimal output of the j-1-th adjustable hydropower station to obtain the total adjustable hydropower output in the t-th scheduling period and the t+1-th scheduling period, wherein when j=1, the optimal output of the j-1-th adjustable hydropower station is set to 0, substitute the total adjustable hydropower output corresponding to the discrete water level at time t1 into the objective function called in step S5, and select the discrete water level corresponding to the minimum objective function value as the optimal water level of the j-th adjustable hydropower station at time t1; S53, determine whether t2 reaches the end of the dispatch period. If not, execute t0=t0+△t and return to execute S51. If yes, calculate the optimal output process of each dispatch period within the dispatch period of the jth adjustable hydropower station according to the optimal water level at each time point of the jth adjustable hydropower station; S54, determine whether there is another adjustable hydropower station downstream of the jth adjustable hydropower station. If so, execute j=j+1 and return to execute S51. If not, output the optimal output process of each adjustable hydropower station in each scheduling period during the scheduling period.

6. A method for joint operation and dispatching of a multi-energy system based on horizontal pumped storage according to claim 5, characterized in that: The specific method of discretizing the initial water level at time t1 is: There are a number of discrete water levels above and below the initial water level at time t1, a total of 2a discrete water levels, of which the nth discrete water level from low to high is calculated by the following formula: With n，jt1 =f -1 (In n，jt1 ) V n，jt1 =V jt1 +(n-a)*0.95 |n-a| *ΔQ*Δt In the above formula, Z n，jt1 represents the nth discrete water level of the initial water level of the jth adjustable hydropower station at time t1, f -1 is the inverse function of the water level and storage capacity of the hydropower station, a is a natural number greater than or equal to 1, n is a natural number greater than or equal to 1 and less than or equal to 2a, V n，jt1 V represents the nth discrete water storage capacity of the jth adjustable hydropower station at time t1, jt1 represents the water storage capacity of the jth adjustable hydropower station at time t1, ΔQ represents the preset discrete step length of flow, and Δt represents the step length of the scheduling period.

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