Short-term optimal scheduling method for energy storage pumps in integrated water-solar-storage system

Abstract

The present invention discloses a short-term optimization scheduling method for an integrated water-photovoltaic-storage system configured with an energy storage pump, which is applied to the integrated water-photovoltaic-storage system. The method comprises: obtaining characteristic parameters of a hydropower unit, and calculating the forced capacity output of the hydropower unit based on the characteristic parameters of the hydropower unit; obtaining characteristic parameters of a photovoltaic system, and calculating the photovoltaic output based on the characteristic parameters of the photovoltaic system; calculating the load difference according to the forced capacity output and photovoltaic output of the hydropower unit and the load demand value of the power grid; adjusting the adjustable capacity output of the hydropower unit or the output of the energy storage pump according to the load difference; the method helps to reduce the adverse effects of random fluctuations in photovoltaic output and give full play to the complementary advantages of the integrated system, which is of great significance to ensuring the safety and stability of the power grid.

Description

Technical Field

[0001] The invention belongs to the technical field of capacity configuration of energy storage pumps in hydropower stations, and in particular to a short-term optimal dispatching method for configuring energy storage pumps in a water-solar-storage integrated system. Background Art

[0002] The installed capacity of new energy power generation such as wind power and photovoltaic power is constantly increasing, and the power generation is constantly increasing, but there are problems of poor stability and strong volatility. Among them, instability will cause frequency fluctuations of the entire power grid, which poses a certain threat to the smooth operation of the power system. Multi-energy combined power generation (such as integrated water, photovoltaic and storage systems) can effectively reduce the adverse effects of the volatility of single energy power generation.

[0003] Since photovoltaic power generation has the characteristics of anti-peak regulation, and the energy demand of the power grid is a segmented and nonlinear indicator. Photovoltaic output is generated in the form of "steamed buns". The excess photovoltaic output at noon can supply power to the energy storage pump station to make up for the insufficient power generation of the system caused by the insufficient water level of the hydropower station at night. According to the actual working conditions, it is necessary to establish a water-light combined power generation model based on the stable operation conditions of the hydraulic unit and on the basis of meeting the power supply guarantee rate to reduce the abandonment rate of water and light. At present, there are few studies on the configuration of a certain capacity of energy storage pump station for mixed flow hydropower stations and the joint operation with new energy power generation (such as photovoltaics) in the surrounding areas. How to obtain a suitable capacity ratio of hydropower, photovoltaics, and energy storage pumps to ensure that the water-light energy storage integrated system has good output performance under the premise of high flexibility of the mixed flow hydropower station is an urgent problem to be solved.

[0004] In the "hydro-photovoltaic-storage integrated" system, hydropower units will bear more peak-shaving and frequency-regulating tasks, and will inevitably cause the units to operate in the vibration zone. Therefore, in the process of configuring the energy storage pump, it is necessary to consider the vibration zone constraints of the hydropower units, so as to ensure a sufficiently low abandonment rate of solar power and water and environmental flow restrictions, while meeting the requirements of relevant indicators of the power system. Therefore, the reasonable capacity configuration of the energy storage pump considering the vibration zone constraints is an important factor that must be considered in the "hydro-photovoltaic-storage integrated" power generation.

[0005] Therefore, how to take the vibration zone constraints into account when configuring the energy storage pump so as to ensure a sufficiently low abandonment rate of solar and water resources and environmental flow restrictions while also meeting the requirements of the power supply guarantee rate of the power system has become a key issue in current research. Summary of the invention

[0006] In view of the above problems, the present invention provides a short-term optimization scheduling method for configuring an energy storage pump for an integrated water-photovoltaic-storage system, which aims to solve some of the above technical problems. By configuring an energy storage pump of a certain capacity for a conventional hydropower station, the conventional hydropower in the integrated system has a certain energy storage function. The energy storage pump can use the surplus electricity to pump water to the upstream reservoir when photovoltaic power generation is sufficient to replenish the water volume of the upstream reservoir. When the photovoltaic output is insufficient, the upstream reservoir uses its adjustable capacity to increase the power generation. This method will help to reduce the adverse effects of random fluctuations in photovoltaic output and give full play to the complementary advantages of the integrated system to support the large-scale grid connection of renewable energy such as photovoltaics, which is of great significance to ensuring the safe, stable, economical and high-quality operation of the power grid.

[0007] The embodiment of the present invention provides a short-term optimization scheduling method for configuring an energy storage pump in a water-photovoltaic-storage integrated system, which is applied to the water-photovoltaic-storage integrated system. The method includes:

[0008] S1. Obtain characteristic parameters of a hydropower unit, and based on the characteristic parameters of the hydropower unit, calculate the mandatory capacity output of the hydropower unit; obtain characteristic parameters of a photovoltaic system, and based on the characteristic parameters of the photovoltaic system, calculate the photovoltaic output;

[0009] S2. Calculate the load difference according to the forced capacity output of the hydropower unit and the photovoltaic output, combined with the load demand value of the power grid;

[0010] S3. According to the load difference, the adjustable capacity output of the hydropower unit or the output of the energy storage pump is adjusted.

[0011] Furthermore, it also includes:

[0012] S4. Determine whether the integrated water-solar-storage system meets the constraints:

[0013] If the integrated water, photovoltaic and storage system meets the constraint conditions, it will operate according to the adjusted storage power of the energy storage pump or the adjustable capacity output of the hydropower unit;

[0014] If the integrated water-photovoltaic-storage system does not meet the constraint conditions, the flexibility ratio of the hydropower unit is corrected, and then the characteristic parameters of the hydropower unit and the photovoltaic system are re-obtained.

[0015] Furthermore, in said S1, the characteristic parameters of the hydropower unit include: the efficiency of the hydropower unit, the maximum flow of the hydropower unit, and the forced flow of the hydropower unit.

[0016] Furthermore, in said S1, the characteristic parameters of the photovoltaic system include: photovoltaic power generation capacity and average value of regional radiation intensity.

[0017] Further, in S2, the calculation formula of the load difference is expressed as:

[0018]

[0019] Among them, P d (t) represents the load difference at time t; P inflexible (t) represents the non-adjustable capacity output at time t; L(t) represents the grid load demand value at time t; P pv (t) represents the photovoltaic output at time t; Indicates the forced capacity output of the hydropower unit.

[0020] Furthermore, in S3, the adjustable capacity output of the hydropower unit is adjusted according to the load difference, which is expressed by the formula:

[0021]

[0022] in, represents the adjustable capacity output of the hydropower unit at time t; P d (t) represents the load difference of the hydropower unit at time t; represents the adjustable flow rate of the upper reservoir that can be used by the hydropower unit at time t; η represents the efficiency of the hydropower unit; ρ represents the density of water; g represents the acceleration of gravity; h(t) represents the water level difference between the reservoir and the hydropower unit; It indicates the maximum ramp rate of the hydropower unit; Δt indicates the time interval.

[0023] Furthermore, in S3, the output of the energy storage pump is adjusted according to the load difference, which is expressed by the formula:

[0024]

[0025] Among them, P pump (t) represents the output of the energy storage pump at time t; P d (t) represents the load difference at time t; Q pump (t) represents the pumping flow rate of the energy storage pump at time t; η pump represents the efficiency of the energy storage pump; ρ represents the density of water; g represents the acceleration of gravity; h(t) represents the water level difference between the reservoir and the hydropower unit; Indicates the maximum climbing rate of the energy storage pump; Δt indicates the time interval.

[0026] Furthermore, the constraints include: system power balance constraints, upper reservoir constraints, hydropower output constraints, lower reservoir constraints, energy storage pump constraints and photovoltaic output constraints.

[0027] Furthermore, the flexibility ratio of the hydropower unit is expressed as:

[0028]

[0029] Among them, C OR It indicates the flexibility ratio of hydropower units; represents the adjustable flow of the upper reservoir of the hydropower unit at time t; Represents the forced flow of the hydropower unit at time t.

[0030] Furthermore, the objective functions of the integrated water, photovoltaic and storage system include: a maximum power generation objective function, a maximum system benefit objective function, a minimum output and load deviation objective function, and a maximum hydropower unit efficiency objective function.

[0031] Compared with the prior art, the short-term optimization scheduling method for configuring an energy storage pump for a water-photovoltaic-storage integrated system described in the present invention has the following beneficial effects:

[0032] Relevant constraints and system optimization objective functions are given respectively. Among the constraints, an active vibration avoidance strategy for the Francis hydropower unit is given, in order to solve the problems of vibration, poor stability and strong volatility of the Francis hydropower unit under the joint power generation of cascade hydropower, so that the Francis hydropower station can operate safely and reliably under the condition of avoiding the vibration area, support the large-scale grid connection of photovoltaic power, and participate in grid regulation at the same time.

[0033] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0036] Figure 1 A flow chart of a short-term optimization scheduling method for configuring an energy storage pump for a water-solar-storage integrated system provided in an embodiment of the present invention.

[0037] Figure 2 Schematic diagram of the integrated water-photovoltaic-storage system provided in an embodiment of the present invention.

[0038] Figure 3 A schematic diagram of water volume changes in a hydroelectric power generation system provided in an embodiment of the present invention.

[0039] Figure 4 A schematic diagram of water volume changes in a hydroelectric power generation system equipped with an energy storage pump provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0041] See also Figure 1 As shown, the embodiment of the present invention provides a short-term optimization scheduling method for configuring an energy storage pump in a water-solar-storage integrated system, which specifically includes the following steps:

[0042] S1. Obtain characteristic parameters of a hydropower unit, and based on the characteristic parameters of the hydropower unit, calculate the mandatory capacity output of the hydropower unit; obtain characteristic parameters of a photovoltaic system, and based on the characteristic parameters of the photovoltaic system, calculate the photovoltaic output;

[0043] S2. Calculate the load difference according to the forced capacity output of the hydropower unit and the photovoltaic output, combined with the load demand value of the power grid;

[0044] S3. According to the load difference, the adjustable capacity output of the hydropower unit or the output of the energy storage pump is adjusted.

[0045] S4. Determine whether the integrated water-solar-storage system meets the constraints:

[0046] If the integrated water, photovoltaic and storage system meets the constraint conditions, it will operate according to the adjusted storage power of the energy storage pump or the adjustable capacity output of the hydropower unit;

[0047] If the integrated water, photovoltaic and storage system does not meet the constraint conditions, the flexibility ratio of the hydropower unit is corrected.

[0048] The following is a detailed description of each of the above steps.

[0049] In the above step S1, refer to Figure 2 As shown, firstly, a mathematical model of the "water-photovoltaic-storage integration" system is established, including a hydropower generation system model, a photovoltaic generation system model, a load model and an energy storage pump model; the specific contents are as follows:

[0050] (1) Hydropower system model

[0051] Schematic diagram of water volume changes in a hydropower generation system Figure 3 As shown in the figure, the change in water volume V in the upstream reservoir upper Includes natural runoff and natural inflow Precipitation Evaporation and total outflow Total outflow including forced water Adjustable water volume and overflow water Among them, the mandatory water volume is used to ensure sufficient downstream runoff and water volume in the lower reservoir; the adjustable water volume is used to participate in regulating the output of renewable energy such as photovoltaic power generation to smooth its randomness and volatility and ensure the stability of the grid load; the overflow volume is the amount of water released through the spillway when the water level of the upper reservoir approaches the critical value. The relationship between the water volume changes in the upstream reservoir is as follows:

[0052]

[0053] Among them, V upper Indicates the change of water volume in the upper reservoir; It represents the natural inflow of natural runoff from the upper reservoir; Indicates the evaporation of the upper reservoir; Indicates the total outflow of water from the upper reservoir; Indicates the mandatory water volume of the upper reservoir; Indicates the adjustable water volume of the upper reservoir; Indicates the overflow water volume of the upper reservoir;

[0054] Correspondingly, the total outflow of the upstream reservoir is It consists of three parts: mandatory flow Adjustable flow and overflow flow

[0055] The total outflow of the upstream reservoir at time t is as follows:

[0056]

[0057] Then the capacity of the upstream reservoir at time t+Δt can be expressed as:

[0058]

[0059] Where: Q pump (t) represents the pumping flow rate of the energy storage pump at time t, m 3 / s; Δt represents the time interval, which is 1h.

[0060] Here, the flexibility ratio C is introduced OR To characterize the forced flow With adjustable flow The relationship between the flexibility ratio C OR Determines the amount of water that can be used flexibly by the hydropower station. Theoretically, when C OR →1, the hydropower station water storage will operate as an adjustable flow (i.e. ) and hardly provides a minimum stable load (i.e. ). In the embodiment of the present invention, C is set ORis 0.6.

[0061]

[0062] From formula (4), it is easy to get:

[0063]

[0064] Forced flow Adjustable flow The corresponding hydropower station output is the mandatory capacity output and adjustable capacity output Total output is MW.

[0065] Forced capacity output of hydropower unit at time t It is expressed as:

[0066]

[0067] In the formula, η represents the efficiency of the hydropower unit, and a relatively conservative value η is taken. turb =80%; ρ represents the density of water, ρ = 1000kg / m 3 ; g represents the acceleration due to gravity, which is 9.81 m / s 2 ; h(t) represents the water level difference between the reservoir and the hydropower unit, in m; Q max Indicates the maximum flow of the hydropower unit, take Q max ≈P rated / (ηρgh max ), where P rated Indicates the rated power of the hydropower unit in MW; h max It represents the maximum hydraulic head of the reservoir, in m.

[0068] Adjustable capacity output of hydropower unit at time t It is expressed as:

[0069]

[0070] In the formula, represents the adjustable capacity output of the hydropower unit at time t; represents the adjustable flow of the upper reservoir of the hydropower unit at time t; η represents the efficiency of the hydropower unit; ρ represents the density of water; g represents the acceleration of gravity; h(t) represents the water level difference between the reservoir and the hydropower unit; Δt represents the time interval; P d (t) is the sum of the forced hydropower and photovoltaic output at time t P inflexible The difference between (t) (non-adjustable capacity output) and the power load demand L(t), i.e. the load difference; ΔP d (t) = P d (t)-Pd (t-Δt) determines whether the hydropower plant should be in a ramp-up state (ΔP d (t)<0) or decrease (ΔP d (t)≥0) state; It is the maximum climbing rate of the hydropower unit.

[0071] (2) Photovoltaic power generation system model

[0072] The photovoltaic power generation system consists of photovoltaic arrays, batteries and other equipment, which can convert light radiation into electrical energy. The power control of the photovoltaic power generation system is mainly determined by the radiation intensity. Changes in weather and seasons in the natural environment will cause changes in the light intensity at the same location of the photovoltaic panel, thereby causing changes in the system power output. Therefore, the output power of the photovoltaic power generation system is a function related to the radiation intensity:

[0073] P pv (t) = c pv ·CF pv (t) (8)

[0074] Where: P pv (t) represents the photovoltaic output at time t; c pv Indicates photovoltaic power generation capacity, MW; CF pv (t) is expressed as the average regional radiation intensity to simulate the photovoltaic power generation output.

[0075] (3) Load model

[0076] For the reservoir of a large hydropower station, the non-adjustable capacity output P inflexible The load difference P between (t) (the sum of hydropower forced output and photovoltaic output) and the grid load demand value L(t) d (t) is calculated as follows:

[0077]

[0078] Where P d (t) represents the load difference at time t; P inflexible (t) represents the non-adjustable capacity output at time t; P pv (t) represents the photovoltaic output at time t; L(t) represents the grid load demand value to be followed; Indicates the forced capacity output of the hydropower unit.

[0079] (4) Energy storage pump model

[0080] By configuring a storage pump of a certain capacity, the discharged water from power generation is pumped back to the upstream reservoir for storage to consume the excess photovoltaic power generation. When the photovoltaic power generation is insufficient, the storage pump reduces or stops pumping water, and the hydropower station releases water to generate electricity to increase the total power generation of the combined power generation system. Figure 4 Schematic diagram of water volume changes in a hydropower generation system equipped with an energy storage pump.

[0081] The flow balance part of the change comes from the low-capacity downstream reservoir, only the adjustable flow Q flexible (t) can be used for pumping water, and the forced flow rate Q stable (t) must be discharged directly downstream to ensure the balance of water volume downstream. Assuming that the surface area of ​​the lower reservoir is much smaller than that of the upper reservoir, precipitation and evaporation can be ignored. Therefore, the water volume of the downstream reservoir is:

[0082]

[0083] Among them, V lower (t) represents the change of water volume in the lower reservoir at time t; represents the forced flow of the upper storage at time t; represents the adjustable flow of the upper reservoir at time t; Q pump (t) is the pumping flow rate of the energy storage pump at time t, is the overflow flow of the lower reservoir. The power stored by the energy storage pump is:

[0084]

[0085] Among them, P pump (t) represents the output of the energy storage pump at time t; P d (t) represents the load difference at time t; Q pump (t) represents the pumping flow rate of the energy storage pump at time t; η pump represents the efficiency of the energy storage pump; ρ represents the density of water; g represents the acceleration of gravity; h(t) represents the water level difference between the reservoir and the hydropower unit; Indicates the maximum climbing rate of the energy storage pump; Δt indicates the time interval. The calculation is as follows:

[0086]

[0087] in, Indicates the maximum water flow rate of the energy storage pump.

[0088] Obtain the characteristic parameters of the hydropower unit, i.e., the efficiency of the hydropower unit, the maximum flow rate of the hydropower unit, and the forced flow rate of the hydropower unit, from the above hydropower generation system model; calculate the forced capacity output of the hydropower unit (i.e., the above formula (6)) according to the obtained characteristic parameters of the hydropower unit;

[0089] Obtain photovoltaic system characteristic parameters from the above photovoltaic power generation system model, namely, photovoltaic power generation capacity and average value of regional radiation intensity; calculate photovoltaic output (i.e., the above formula (8)) based on the obtained photovoltaic system characteristic parameters;

[0090] In the above step S2, the load difference is calculated based on the forced capacity output of the hydropower unit calculated by the above formula (6) and the photovoltaic output calculated by the above formula (8), combined with the grid load demand value, that is, the above formula (9);

[0091] In the above step S3, the adjustable capacity output of the hydropower unit or the output of the energy storage pump is adjusted according to the load difference, referring to the above formula (7) and formula (14); specifically including:

[0092] Load difference P d (t) Making judgments:

[0093] ① If the load difference P d (t)>0, indicating that the sum of the hydropower output and the photovoltaic output is greater than the grid load demand value. Since the electric energy itself cannot be stored in large quantities for a long time, power abandonment will occur. pump (t) to pump water to consume the surplus electricity, while the hydropower unit maintains the forced output No need to increase power generation;

[0094] ② If the load difference P d (t)<0, indicating that the sum of the hydropower forced output and the photovoltaic output is less than the grid load demand value, which does not meet the power demand at that moment. Increase power generation without the storage pump working;

[0095] ③If the load difference P d (t) = 0, indicating that the sum of the hydropower output and the photovoltaic output just meets the grid load demand value, so the total power generation of the non-adjustable part P inflexible (t) remains unchanged.

[0096] In the above step S4, it is determined whether the relevant variables in the integrated water-solar-storage system meet the constraint conditions; if so, the system is operated according to the adjusted storage power of the energy storage pump or the adjustable capacity output of the hydropower unit; if not, the flexibility ratio of the hydropower unit is corrected, and then the characteristic parameters of the hydropower unit and the photovoltaic system are re-acquired.

[0097] The constraints include: system power balance constraints, upper reservoir constraints, hydropower output constraints, lower reservoir constraints, energy storage pump constraints and photovoltaic output constraints; the specific contents are as follows:

[0098] (1) System power balance constraints

[0099] Since electric energy does not have the property of large-scale storage, the total power generation of the joint operation system should be equal to the total power consumption. Without considering the system network loss, the system power balance equation is:

[0100]

[0101] Where P load (t) represents the system load at time t, in MW; P hydro (t) represents the hydropower output of the hydropower unit at time t; P pv (t) represents the photovoltaic output at time t; P pump (t) represents the output of the energy storage pump at time t;

[0102] M represents the number of hydropower units.

[0103] (2) Inventory constraints

[0104] ① Upper reservoir water level constraints

[0105]

[0106] In the formula, H upper (t) represents the water level of the upper reservoir at time t; and They represent the dead water level of the upper reservoir and the highest power generation water level respectively, in m.

[0107] ② Upper reservoir water volume constraints

[0108]

[0109] Where V t hydro Indicates the change in water volume in the upper reservoir at time t; and Respectively represent the minimum and maximum water volume of the upper reservoir at time t, in m 3 .

[0110] ③ Constraints on upper reservoir discharge flow

[0111]

[0112] In the formula, It represents the total outflow flow of the upper storage at time t; and They are the minimum and maximum discharge of the upper reservoir at time t, in m 3 / s. Where:

[0113]

[0114] ④ Upper reservoir water balance constraints

[0115]

[0116] Where V upper (t) represents the change in water volume of the upper reservoir at time t, in m 3 ; is the inflow at time t, S(t) is the discharge flow of the upper reservoir at time t, in m 3 / s; Δt is the time interval, the unit is h.

[0117] (3) Hydropower output constraints

[0118] ①Hydropower output constraints

[0119]

[0120] Where P hydro (t) is the output of the hydropower unit at time t, MW; A is the output coefficient of the hydropower unit; Q(t) is the power generation flow of the hydropower unit at time t, m 3 / s;h i (t) is the water head of the i-th hydropower unit at time t, m; and They are the uphill and downhill rates of the hydropower unit, MW / h.

[0121] ②Constraints on hydropower output vibration zone

[0122] Due to the complex structure of the hydropower unit, the coupling of different vibration factors will cause the unit's operating state to change, seriously affecting its safe operation. Therefore, the unit needs to avoid the vibration zone. If the hydropower unit has I vibration zone, the constraint condition for the hydropower unit to avoid the vibration zone is:

[0123]

[0124] Where P min and P max are the minimum and maximum output of the hydropower unit, P H (t) is the output of the hydropower unit at the tth moment, P i D (t) and P i U (t) are the lower and upper limit outputs of the hydropower unit in the ith vibration zone, respectively. P1 D (t) is the lower limit output of the first vibration zone of the hydropower unit, It is the upper limit output of the hydropower unit in the first vibration zone, in MW.

[0125] (4) Download Constraints

[0126] ①Lower reservoir water level constraints

[0127]

[0128] In the formula, H lower (t) is the lower reservoir water level at time t, and are the minimum and maximum water levels of the lower reservoir, m.

[0129] ② Reservoir water volume constraints

[0130]

[0131] Where V pump (t) is the change in water volume in the lower reservoir at time t, and are the minimum and maximum water volume of the lower reservoir at time t, m 3 .

[0132] ③Lower reservoir water balance constraints

[0133]

[0134] Where V lower (t) is the change in water volume in the lower reservoir at time t, m 3 ;Q pump (t) is the water flow rate of the energy storage pump to the reservoir at time t, m 3 / s; Δt is the time interval, h; are the precipitation and evaporation of the lower reservoir, m 3 (Assuming that the surface area of ​​the lower reservoir is much smaller than that of the upper reservoir, the precipitation and evaporation of the lower reservoir are ignored. (5)

[0136] ① Constraints on pumping flow of energy storage pumps

[0137]

[0138] In the formula, Q pump (t) is the pumping flow rate of the energy storage pump at time t, is the maximum pumping flow rate of the energy storage pump, m 3 / s.

[0139] ②Energy storage pump output constraints

[0140]

[0141] Where P pump (t) is the output of the energy storage pump at time t, MW; A pump is the output coefficient of the energy storage pump; Q i (t) is the pumping flow rate of the energy storage pump, m 3 / s;hpump (t) is the head of the energy storage pump at time t, m; and Respectively represent the rising and falling climbing rates of the energy storage pump, MW / h.

[0142] (6) Photovoltaic output constraints

[0143] The photovoltaic output constraint condition is that the photovoltaic output at time t does not exceed its maximum predicted output, that is:

[0144]

[0145] Where P pv (t) is the photovoltaic output at time t, is the maximum predicted photovoltaic output at time t, MW.

[0146] The objective function of the integrated water-solar-storage system is as follows:

[0147] The "integrated water, photovoltaic and energy storage" system needs to consider the power balance constraints and related constraints of each link of hydropower, photovoltaics and energy storage pumps.

[0148] (1) Maximum power generation

[0149] Divide a day into 24 periods, and take the maximum power generation of the "water-solar-storage integration" system as the objective function:

[0150]

[0151] Where P load (t) is the total output of the “water-solar-storage integrated” system at time t, MW; T is the total number of intervals within the time range; Δt is the time interval.

[0152] (2) Maximum system benefits

[0153] The objective function is to maximize the benefits of the "water-solar-storage integration" system, as shown in the following formula:

[0154]

[0155] Where P pv (t), P hydro (t) are the photovoltaic and hydropower grid-connected power at time t, P pump (t) is the pumping power of the energy storage pump at time t, in MW; C t The bundled on-grid electricity price of the “hydro-photovoltaic-storage integrated system” at time t, C p is the electricity price of the energy storage pump at time t, in yuan / MW·h; T is the operating time, in h.

[0156] (3) Minimum deviation between output and load

[0157] In the "water-photovoltaic-storage integrated" system, due to the anti-peaking characteristics of photovoltaic power generation and the limited regulation capacity of hydropower, there is always a phenomenon of abandoning light or failing to meet load demand. Therefore, the minimum deviation between load demand and output is used as the objective function:

[0158]

[0159] Where T is the total number of intervals within the time range; L(t) is the grid load curve at time t; P load (t) is the total output of the “water-solar-storage integrated system” at time t, in MW.

[0160] (4) Hydropower units have the highest efficiency

[0161] In the "hydro-solar-storage integration" system, since the load distribution within the hydropower station meets the output constraints and vibration avoidance constraints of conventional hydropower units, there is always a problem of diversified load combinations assigned to each hydropower unit under the current water head. Therefore, in order to reduce the life loss of the hydropower unit runner, etc., the highest efficiency value of each hydropower unit in the load combination under the current water head is used as the objective function:

[0162] max[η i ] (33)

[0163] Where η i is the power generation efficiency of the i-th state hydropower unit, which can be obtained by the difference of the power-efficiency-head curve after the hydropower station efficiency test.

[0164] The evaluation index system of water-solar-storage integrated system is as follows:

[0165] (1) Abandoned light rate

[0166] The abandoned light rate is used to describe the proportion of the excess light energy that cannot be used relative to the load demand. The calculation method is:

[0167]

[0168] In the formula, is the abandoned light power of the “water-solar-storage integrated system” at time t, P pv (t) is the photovoltaic power generation output at time t, in MW; T is the total power generation cycle of the system.

[0169] (2) Power supply guarantee rate

[0170] The power supply guarantee rate is an indicator used to evaluate the reliability of the power transmission end in meeting the power demand side. The smaller the power supply guarantee rate, the more cases where the power demand cannot be met, and the worse the power supply capacity of the "water-solar-storage integration" system. The power supply guarantee rate is defined as:

[0171]

[0172] (3) Annual utilization rate of hydropower

[0173] The annual utilization rate of hydropower is used to quantify the proportion of hydropower utilization hours in a year. The greater the annual utilization rate of hydropower, the higher the proportion of hydropower utilization hours in a year, and the better the complementary performance of the "hydro-solar-storage integration" system.

[0174] The hydropower utilization rate equation is defined as:

[0175]

[0176] In the formula, It is the annual utilization hours of hydropower, in h.

[0177] Next, the embodiment of the present invention is further described through example analysis.

[0178] Since the installed capacity of hydropower is affected by upstream water and climate, its installed capacity has been basically determined. Based on the initial planned installed capacity of each power source, this example sets the installed capacity to 2200MW-3800MW based on the initial planned photovoltaic installed capacity of 3000MW, in order to explore the impact of photovoltaic capacity changes on the power transmission capacity of the "water-photovoltaic-storage integration" system. The specific plan and indicator results are shown in the table below.

[0179] Table 1 Evaluation index results under different photovoltaic installed capacities

[0180]

[0181]

[0182] The hydropower installed capacity is maintained at 320MW and the energy storage pump installed capacity is maintained at 1000MW, and the photovoltaic installed capacity is changed from 2200MW to 3800MW. According to the analysis of the obtained data results, with the continuous expansion of the photovoltaic installed capacity, the system's abandoned light rate gradually increased from the initial 0.35% to 22.71%; while the power supply guarantee rate showed a significant upward trend, from the minimum value of 58.43% to the maximum value of 97.33% when the photovoltaic unit increased to 3800MW. In addition, the annual utilization rate of the hydropower unit showed a downward trend, from 54.59% when the photovoltaic installed capacity was 2200MW to 48.74% when the photovoltaic installed capacity was 3800MW.

[0183] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A short-term optimal scheduling method for energy storage pumps configured in a water-photovoltaic-storage integrated system, applied to a water-photovoltaic-storage integrated system, characterized in that: include: S1. Obtain characteristic parameters of a hydropower unit, and based on the characteristic parameters of the hydropower unit, calculate the forced capacity output of the hydropower unit; Acquiring characteristic parameters of a photovoltaic system, and calculating photovoltaic output based on the characteristic parameters of the photovoltaic system; S2. According to the forced capacity output of the hydropower unit and the photovoltaic output, combined with the load demand value of the power grid, the load difference is calculated; the calculation formula of the load difference is expressed as: Among them, P d (t) represents the load difference of the hydropower unit at time t; P inflexible (t) represents the non-adjustable capacity output at time t; L(t) represents the grid load demand value at time t; P pv (t) represents the photovoltaic output at time t; Indicates the mandatory capacity output of the hydropower unit; S3. According to the load difference, the adjustable capacity output of the hydropower unit or the output of the energy storage pump is adjusted; wherein: According to the load difference, the adjustable capacity output of the hydropower unit is adjusted, which is expressed by the formula: in, represents the adjustable capacity output of the hydropower unit at time t; represents the adjustable flow rate of the upper reservoir that can be used by the hydropower unit at time t; η represents the efficiency of the hydropower unit; ρ represents the density of water; g represents the acceleration of gravity; h(t) represents the water level difference between the reservoir and the hydropower unit; It indicates the maximum ramp rate of the hydropower unit; Δt indicates the time interval; According to the load difference, the output of the energy storage pump is adjusted, which is expressed by the formula: Among them, P pump (t) represents the output of the energy storage pump at time t; Q pump (t) represents the pumping flow rate of the energy storage pump at time t; η pump represents the efficiency of the energy storage pump; Indicates the maximum climbing rate of the energy storage pump; S4. Determine whether the integrated water-solar-storage system meets the constraints: If the integrated water, photovoltaic and storage system meets the constraint conditions, it will operate according to the adjusted storage power of the energy storage pump or the adjustable capacity output of the hydropower unit; If the integrated water-photovoltaic-storage system does not meet the constraint conditions, the flexibility ratio of the hydropower unit is corrected, and then the characteristic parameters of the hydropower unit and the photovoltaic system are re-obtained; The constraints include: system power balance constraints, upper reservoir constraints, hydropower output constraints, lower reservoir constraints, energy storage pump constraints and photovoltaic output constraints.

2. The short-term optimization scheduling method for configuring an energy storage pump for a water-photovoltaic-storage integrated system according to claim 1 is characterized in that: In S1, the characteristic parameters of the hydropower unit include: the efficiency of the hydropower unit, the maximum flow of the hydropower unit, and the forced flow of the hydropower unit.

3. The short-term optimization scheduling method for configuring an energy storage pump for a water-photovoltaic-storage integrated system according to claim 1 is characterized in that: In S1, the characteristic parameters of the photovoltaic system include: photovoltaic power generation capacity and average regional radiation intensity.

4. The short-term optimization scheduling method for configuring an energy storage pump for a water-photovoltaic-storage integrated system according to claim 1, characterized in that: The flexibility ratio of the hydropower unit is expressed as: Among them, C OR It indicates the flexibility ratio of hydropower units; Represents the forced flow of the hydropower unit at time t.

5. The short-term optimal scheduling method for configuring an energy storage pump for a water-photovoltaic-storage integrated system according to claim 1, characterized in that: The objective functions of the integrated water, photovoltaic and storage system include: a maximum power generation objective function, a maximum system benefit objective function, a minimum output and load deviation objective function and a maximum hydropower unit efficiency objective function.

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