A method for dispatching power systems taking into account the flexibility of battery energy storage and pumped storage

Abstract

The present invention discloses a method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage, including considering the fluctuation of the net load of the system and establishing an upward / downward flexibility demand model; taking the total cost of dispatching energy cost, standby cost and FRP call cost as the minimum as the goal, establishing a mixed integer linear programming model based on day-ahead safety constraint unit combination and real-time economic redispatch; taking the IEEE-RTS-24 node system as an example, considering different typical scenario scenarios, and comparing and verifying the flexibility of system operation. The present invention makes full use of the flexible supply capacity of conventional units, battery energy storage and pumped storage, and reasonably formulates unit combination and dispatching plans to reduce system operating costs and improve system operating flexibility.

Description

Technical Field

[0001] The present invention relates to the field of power system dispatching operation, and particularly to a power system dispatching method considering the flexibility of battery energy storage and pumped - storage energy storage. Background Art

[0002] Driven by the dual - carbon goal, to build a clean, low - carbon, safe and efficient energy system, the high - proportion access of new energy will become the basic feature and development form of the future power system. At the same time, the intermittency and volatility of new - energy output require the power system to have higher flexibility. Flexibility, as the key to the operation of a power system with a high proportion of new energy, has attracted extensive research.

[0003] Power system flexibility refers to "the ability of a power system to reliably and economically manage the supply - demand changes and uncertainties on all relevant time scales". At present, the flexibility of China's power system is mainly provided by conventional generating units on the supply side. However, the increase in new - energy penetration rate will lead to the inability of generating units alone to meet the increasing demand for system flexibility, posing higher requirements for system flexible regulation resources. Flexible ramp products (FRP) is a new type of power - market trading variety. The unit of FRP is MW / min, including two types: flexible ramp - up (FRU) and flexible ramp - down (FRD). In the current power - market dispatching, the time scale of FRP trading is mainly the real - time market. However, with the increase in new - energy penetration rate, it may lead to insufficient system flexible regulation ability.

[0004] Energy - storage systems can provide flexible regulation ability for power systems, ensure the balance of power supply and demand, take into account system safety and economy, and reduce energy - using costs. Current research and applications have proved the role of battery energy storage systems (BESS) in providing FRP and solving load imbalance. However, the FRP of other emerging energy - storage technologies such as pumped - hydro energy storage (PHES), compressed - air energy storage, etc. has not been widely studied. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above problems and / or problems existing in the existing power system dispatching methods, the present invention is proposed.

[0007] Therefore, the problem to be solved by the present invention is the need for a power system dispatching method that takes into account the flexibility of battery energy storage and pumped storage, so as to solve the problem that the current existing methods may lead to insufficient system flexibility supply capacity.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage, comprising:

[0009] Considering the net load fluctuation of the system, the upward flexibility FRU and downward flexibility FRD demand models are established;

[0010] With the goal of minimizing the total cost of dispatching energy cost, reserve cost and FRP call cost, a mixed integer linear programming model based on day-ahead safety constraint unit commitment and real-time economic redispatch is established.

[0011] Taking the IEEE-RTS-24 node system as an example, different typical scenario scenarios are considered to compare and verify the system operation flexibility.

[0012] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, wherein: in the step of considering the fluctuation of the net load of the system and establishing the upward flexibility FRU and downward flexibility FRD demand models, the FRU demand and FRD demand of the system are determined by the change in the system demand per unit time, that is, the change in the net load of the system between the next moment and the current moment;

[0013] The system net load calculation formula is:

[0014] NL t =L t -P s,t -P w,t

[0015] In the formula, NL t is the predicted system net load value at time t; L t , P s,t , P w,t They are the system load power, photovoltaic output, and wind power output predicted at time t respectively;

[0016] The specific calculation formula for FRU and FRD requirements is as follows:

[0017]

[0018] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, wherein: taking into account the system flexibility demand, the flexible adjustment capabilities of conventional units, battery energy storage BESS and pumped storage PHES are coordinated and optimized to ensure the balance of system flexibility supply and demand, considering the operation constraints of the system, and establishing the day-ahead safety constraint unit combination and real-time economic re-dispatch model with the minimum total system cost, wherein the day-ahead dispatching time scale is 15 minutes and the real-time dispatching time scale is 5 minutes;

[0019] The objective is to minimize the total cost of scheduling energy cost, standby cost and FRP call cost, and the objective function is as follows:

[0020]

[0021] In the formula, represents the energy cost, reserve cost and FRP call cost in day-ahead scheduling, LC RT To reduce the cost of real-time load dispatch, RC RT It is the penalty cost for abandoning wind and solar power in real-time dispatch; among which,

[0022]

[0023] Where, the first part represents the linearized form of the quadratic cost function of the conventional unit, is the minimum power generation cost of unit i, u i,t is the start / stop status of the i-th unit at time t; the second part is the start / shutdown cost of the conventional unit, y i,t 、z i,t is the start-up action variable and shutdown action variable of unit i; the third part is the cost of PHES pumping and power generation mode; the fourth part is the BESS discharge cost;

[0024]

[0025] In the formula, C res is the standby cost, res i,t 、res ph,t 、res be,t They are the spare capacities of conventional units, PHES, and BESS respectively;

[0026]

[0027] In the formula, C frp is the FRP call cost, RU i,t , R.U. ph,t , R.U. be,t They are respectively the upward flexibility capacity of conventional units, PHES, and BESS, and RD i,t , RD ph,t, RD be,t They are the downward flexibility capacities of conventional units, PHES and BESS respectively.

[0028] As an optimal solution for the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, wherein: a mixed integer linear programming model based on day-ahead safety constraint unit combination and real-time economic re-dispatch is established, and constraints need to be considered. The constraints include conventional unit constraints, PHES model and its operation constraints, battery energy storage model constraints, new energy output constraints, day-ahead flexibility constraints and spare capacity constraints, system flow and safety constraints, implementation flexibility constraints, and power balance constraints.

[0029] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, wherein: the conventional unit constraints include upper and lower limit constraints of conventional unit output, climbing constraints, and unit operation status and start-stop status constraints;

[0030] The conventional unit output upper and lower limit constraints and climbing constraints are expressed as follows:

[0031]

[0032]

[0033] The unit operation status and start-stop status constraints are expressed as follows:

[0034] y i,t -z i,t =u i,t -u i,t-1

[0035] y i,t +z i,t ≤1

[0036] Among them, P i,t is the active power output of conventional unit i at time t, in kW; The upward and downward climbing limits of the unit, in kW / h; It is the starting and stopping climbing limit of the unit, in kW / h.

[0037] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, the mathematical model of PHES and its operation constraints are as follows:

[0038]

[0039]

[0040]

[0041] In the formula, are the power generation and pumping power of PHES, respectively related to the water flow of the upper and lower reservoirs And the upper and lower reservoir heads H UR , H LR Related; η g , η m are the power generation efficiency and pumping efficiency of PHES, respectively; are the water levels of the upper and lower reservoirs respectively; res ph,t They are the power generation energy, pumping energy, and standby power of PHES, RU ph,t , RD ph,t Upward flexibility and downward flexibility provided to PHES.

[0042] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage described in the present invention, the battery energy storage model includes the power balance constraint, charge and discharge power limit constraint, and charge and discharge state constraint of the BESS, which are as follows:

[0043]

[0044]

[0045]

[0046] In order to ensure that the charging and discharging of the energy storage battery are not performed at the same time, the following constraints are also set:

[0047] ψ be,t +ζ be,t ≤1

[0048] In the formula, SOC be,t is the charge state of BESS; is the charging and discharging power of BESS, in kW; ψ be,t , be,t 0-1 variable for the charging and discharging working status of BESS; The energy conversion efficiency during charging and discharging of BESS;

[0049] The new energy output constraints are as follows:

[0050]

[0051] In the formula, The available resources of photovoltaic and wind power.

[0052] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, among the day-ahead flexibility constraints and reserve capacity constraints, the constraints for conventional units, PHES, and BESS in day-ahead dispatching to meet upward / downward flexibility requirements are:

[0053]

[0054] In the formula, The system's day-ahead upward / downward flexibility requirements;

[0055] The backup constraints of the system are:

[0056]

[0057] To ensure the reliability of system operation, the reserve capacity is set to 50% of the maximum output of the conventional units.

[0058] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, the system flow and safety constraints include:

[0059] The transmission power Pf between node b and node n at time t b,n,t :

[0060]

[0061] Transmission line transmission capacity constraints:

[0062]

[0063] In the formula, γ b,n is the transmission line admittance; b,n is the maximum transmission capacity of the transmission line.

[0064] As a preferred solution of the power system dispatching method taking into account the flexibility of battery energy storage and pumped storage as described in the present invention, in which: in real-time dispatching, the FRU / FRD demand is given by the system net load calculation formula, and the system flexibility constraint in real-time re-dispatching is:

[0065]

[0066] The power balance constraint in day-ahead scheduling is:

[0067]

[0068] The power balance constraint in intraday scheduling is:

[0069]

[0070] The beneficial effects of the present invention are as follows: the present invention fully utilizes the flexible supply capabilities of conventional units, battery energy storage and pumped storage, and rationally formulates unit combinations and scheduling plans to reduce system operating costs and improve system operating flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0072] Figure 1 Schematic diagram of system FRP demand in the power system dispatch method considering battery energy storage and pumped storage flexibility.

[0073] Figure 2 Diagram of the adjusted IEEE-RTS-24 node system structure for the power system dispatch method to account for battery energy storage and pumped storage flexibility.

[0074] Figure 3 Typical daily load and renewable energy output curves for the power system dispatch method taking into account the flexibility of battery energy storage and pumped storage.

[0075] Figure 4 The day-ahead dispatch plan of ESS in Scheme 1 of the power system dispatch method considering the flexibility of battery energy storage and pumped storage.

[0076] Figure 5 Real-time power balance of FRP in Scheme 1 for power system dispatch method considering battery energy storage and pumped storage flexibility.

[0077] Figure 6 The FRP day-ahead plan and real-time dispatch diagram are provided for the conventional units in Scheme 4 of the power system dispatch method taking into account the flexibility of battery energy storage and pumped storage.

[0078] Figure 7 The FRP day-ahead plan and real-time dispatch diagram are provided for PHES in Scheme 4 of the power system dispatch method considering battery energy storage and pumped storage flexibility.

[0079] Figure 8 The FRP day-ahead plan and real-time dispatch diagram are provided for the BESS in Scheme 4 of the power system dispatch method considering battery energy storage and pumped storage flexibility. DETAILED DESCRIPTION

[0080] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0081] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0082] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0083] Example 1

[0084] Reference Figures 1 to 3 , which is the first embodiment of the present invention, and provides a method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage:

[0085] S1: Considering the net load fluctuation of the system, the upward flexibility FRU and downward flexibility FRD demand models are established;

[0086] Specifically, the FRU demand and FRD demand of the system are determined by the change in system demand per unit time, that is, the change in net load of the system between the next moment and the current moment, such as Figure 1 It should be noted that, although FRP is a transaction product in the electricity market, the scheduling of the present invention considers the FRP demand, that is, the sequential ramping power of the net load under a unit time scale.

[0087] Figure 1 China, NL 1 and NL 2 is the system net load at t 1 and t 2 The predicted value at time t, the arrow is 1 Real-time system FRU / FRD requirements.

[0088] The system net load calculation formula is:

[0089] NL t =L t -P s,t -P w,t (1)

[0090] In the formula, NL t is the predicted system net load value at time t; L t , P s,t , P w,tThey are the system load power, photovoltaic output, and wind power output predicted at time t respectively.

[0091] The specific calculation formula for FRU and FRD requirements is as follows:

[0092]

[0093] S2: With the goal of minimizing the total cost of dispatching energy cost, reserve cost and FRP call cost, a mixed integer linear programming model based on day-ahead safety constraint unit commitment and real-time economic redispatch is established;

[0094] Specifically, the present invention takes into account the system flexibility requirements, coordinates and optimizes the flexible adjustment capabilities of conventional units, battery energy storage BESS and pumped storage PHES to ensure the balance of system flexibility supply and demand, considers the system operation constraints, and establishes a day-ahead safety-constrained unit combination and a real-time economic re-dispatch model with the minimum total system cost, wherein the day-ahead dispatch time scale is 15 minutes and the real-time dispatch time scale is 5 minutes.

[0095] The goal of the optimization problem is to minimize the total cost of energy cost, reserve cost and FRP call cost in day-ahead dispatch, and the sum of load reduction and wind and solar power abandonment penalty costs in real-time dispatch.

[0096]

[0097] In the formula, represents the energy cost, reserve cost and FRP call cost in day-ahead scheduling, LC RT To reduce the cost of real-time load dispatch, RC RT It is the penalty cost for abandoning wind and solar power in real-time dispatch.

[0098]

[0099] Where, the first part represents the linearized form of the quadratic cost function of the conventional unit, is the minimum power generation cost of unit i, u i,t is the start / stop status of the i-th unit at time t; the second part is the start / shutdown cost of the conventional unit, y i,t 、z i,t are the start-up action variables and shutdown action variables of unit i; the third part is the cost of PHES in pumping and power generation mode; the fourth part is the BESS discharge cost.

[0100]

[0101] In the formula, C res is the standby cost, res i,t 、res ph,t 、res be,tThey are the spare capacities of conventional units, PHES and BESS respectively.

[0102]

[0103] In the formula, C frp is the FRP call cost, RU i,t , R.U. ph,t , R.U. be,t They are respectively the upward flexibility capacity of conventional units, PHES, and BESS, and RD i,t , RD ph,t , RD be,t They are the downward flexibility capacities of conventional units, PHES and BESS respectively.

[0104] Furthermore, in order to establish a mixed integer linear programming model based on day-ahead safety-constrained unit combination and real-time economic redispatch, it is necessary to consider constraints, which include conventional unit constraints, PHES model and its operation constraints, battery energy storage model constraints, new energy output constraints, day-ahead flexibility constraints and spare capacity constraints, system flow and safety constraints, implementation flexibility constraints, and power balance constraints.

[0105] (1) Conventional unit constraints

[0106] Formulas (7-9) are the upper and lower limit constraints and climbing constraints of conventional unit output respectively, and formulas (10-11) are the unit operation status and start-stop status constraints.

[0107]

[0108] y i,t -z i,t =u i,t -u i,t-1 (10)

[0109] y i,t +z i,t ≤1 (11)

[0110] Where P i,t is the active power output of conventional unit i at time t, in kW; It is the upward and downward climbing limit of the unit, in kW / h; It is the starting and stopping climbing limit of the unit, in kW / h.

[0111] (2) PHES model

[0112] Equations (12)-(17) are the mathematical model of PHES and its operation constraints:

[0113]

[0114]

[0115] In the formula, are the power generation and pumping power of PHES, respectively related to the water flow of the upper and lower reservoirs And the upper and lower reservoir heads H UR , H LR Related; η g , η m are the power generation efficiency and pumping efficiency of PHES, respectively; are the water levels of the upper and lower reservoirs respectively; res ph,t They are the power generation energy, pumping energy, and standby power of PHES, RU ph,t , RD ph,t Upward flexibility and downward flexibility provided to PHES.

[0116] (3) Battery energy storage model

[0117] Formulas (18)-(21) are the power balance constraint, charge and discharge power limit constraint, and charge and discharge state constraint of BESS respectively. Formula (21) ensures that the charging and discharging of the energy storage battery are not performed at the same time.

[0118]

[0119]

[0120] ψ be,t +ζ be,t ≤1 (22)

[0121] In the formula, SOC be,t is the charge state of BESS; is the charging and discharging power of BESS, kW; ψ be,t , be,t 0-1 variable for the charging and discharging working status of BESS; It is the energy conversion efficiency during the charging and discharging process of BESS.

[0122] (4) Constraints on new energy output

[0123]

[0124] In the formula, The available resources of photovoltaic and wind power.

[0125] (5) Day-ahead flexibility constraints and reserve capacity constraints

[0126] Formulas (25-26) are the constraints for conventional units, PHES, and BESS to meet the upward / downward flexibility requirements in day-ahead scheduling; Formula (27) is the system's reserve constraint. To ensure the reliability of system operation, the reserve capacity is set to 50% of the maximum output of the conventional units.

[0127]

[0128] In the formula, Provides up / down flexibility requirements for the system day-ahead.

[0129] (6) System power flow and safety constraints

[0130] The transmission power Pf between node b and node n at time t b,n,t Determined by formula (28), formula (29) is the transmission capacity constraint of the transmission line.

[0131]

[0132] In the formula, γ b,n is the transmission line admittance; b,n is the maximum transmission capacity of the transmission line.

[0133] (7) Real-time flexibility constraints

[0134] In real-time scheduling, the FRU / FRD demand is given by equation (1), and equations (30-31) are the system flexibility constraints in real-time rescheduling.

[0135]

[0136] (8) Power balance constraints

[0137] Formula (32) is the power balance constraint in day-ahead scheduling; Formula (33) is the power balance constraint in intraday scheduling.

[0138]

[0139]

[0140] S3: Taking the IEEE-RTS-24 node system as an example, four different typical scenario are considered, and the comparison verifies that the proposed method can effectively improve the system operation flexibility and reduce the operation cost.

[0141] Specifically, taking the IEEE-RTS-24 node system as the basic example model, its peak load is 2900 MW; the total installed capacity of conventional units is 3250 MW; the total installed capacity of the wind farm is 450 MW; the total installed capacity of the PV power station is 550 MW. A battery energy storage device with a capacity of 200 MWh and a power of 50 MW is installed at node 3; a pumped-storage power station with a reservoir capacity of 1 TMC and a power of 200 MW is installed at node 12. Figure 2 It is the structure diagram of the adjusted IEEE-RTS-24 node system.

[0142] The penalty for load curtailment, wind curtailment, and PV curtailment is 100 $ / WMh. The day-ahead flexibility requirement is defined as Kσ t , where σ t is the standard deviation of the net load calculated based on historical data, and K is taken as 1. The load and wind-solar output curves of a typical day in the system are as Figure 3 shown.

[0143] Example 2

[0144] Referring to Figures 4 to 8 , this is the second embodiment of the present invention. In order to better verify and illustrate the technical effects achieved by the method of the present invention, the following 4 schemes are compared and analyzed in this embodiment:

[0145] Scheme 2: On the basis of Scheme 1, the FRP is jointly provided by conventional units and PHES.

[0146] Scheme 3: On the basis of Scheme 1, the FRP is jointly provided by conventional units and BESS.

[0147] Scheme 4: On the basis of Scheme 1, the FRP is jointly provided by conventional units, PHES, and BESS.

[0148] The scheduling comparison results of the 4 schemes are shown in Table 1 and Figure 4-8 .

[0149] Table 1: Scheduling results of different schemes

[0150]

[0151] Figure 4 is the day-ahead scheduling scheme in Scheme 1, Figure 5 is the real-time power balance in Scheme 1. Figure 6-8 is the deviation between the day-ahead plan and the real-time scheduling for the FRP provided by conventional units, PHES, and BESS in Scheme 4.

[0152] The comparison results show that: in Scheme 1, although the FRP purchased from conventional units is used to meet the system flexibility needs in real-time redispatch, the system load will be cut by about 314MWh due to insufficient ramping capacity during certain periods;

[0153] In Option 2, due to the addition of PHES FRP on the basis of Option 1, the operating cost is reduced by $120,000 and the system load shedding is reduced by 46MWh;

[0154] In Scheme 3, the FRP of BESS is incorporated into real-time redispatch, which reduces the operating cost by $140,000 and reduces the system load shedding by 61 MWh compared with Scheme 1.

[0155] In Scheme 4, although conventional units, PHES, and BESS all provide FRP, the reduction in operating costs and system load shedding is not significant compared with Schemes 2 and 3. This is because all energy storage devices are involved in the charging and discharging cycle. The system load shedding is reduced to 250MWh and the operating cost is reduced to US$4.57 million, a decrease of 3.18% compared with Scheme 1.

[0156] In addition, from the operating results of Scheme 4, it can be concluded that the system FRU demand is large, and a large number of FRU resources need to be purchased from the day-ahead plan and applied to real-time scheduling, while the system FRD demand is small and can be met only by conventional units.

[0157] In the above four schemes, the system has a great demand for upward flexibility and uses the upward flexibility capacity allocated in the day-ahead plan in real-time scheduling. Although in the day-ahead unit output plan, the unit output meets all net loads without any load reduction, in real-time operation, it can be observed that the upward flexibility capacity of the available units is not enough to meet the changes in net load, and the lack of energy and FRP call plans will lead to a large amount of load reduction in certain periods. On the other hand, when the system net load decreases, the downward flexibility capacity of the available units is sufficient to meet the system FRD demand, so the charging or FRD call of energy storage can be ignored. In addition, by comparing Scheme 2 and Scheme 3, it can be observed that BESS has a faster climbing capability than PHES, so BESS has greater potential than PHES in providing FRP.

[0158] With the continuous increase in the penetration rate of new energy, how to ensure the flexible and safe operation of the power system under the access of large-scale fluctuating power sources is an engineering problem that needs to be considered urgently. To this end, the present invention establishes a quantitative model of upward / downward flexibility demand considering the time-varying characteristics of net load; then considering the FRP supply capacity of BESS and PHES, an optimization scheduling model is constructed from the perspective of optimal total system cost to determine the day-ahead scheduling plan and real-time scheduling strategy of flexible resources. The correctness and effectiveness of the model are verified by examples. The results show that the proposed model can make full use of the flexibility supply capacity of conventional units, BESS and PHES, reasonably formulate unit combinations and scheduling plans, and significantly reduce system operating costs.

[0159] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0160] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0161] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0162] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for dispatching power systems taking into account the flexibility of battery energy storage and pumped storage, Features: include, Considering the net load fluctuation of the system, the upward flexibility FRU and downward flexibility FRD demand models are established; With the goal of minimizing the total cost of dispatching energy cost, reserve cost and FRP call cost, a mixed integer linear programming model based on day-ahead safety constraint unit commitment and real-time economic redispatch is established. Taking the IEEE-RTS-24 node system as an example, different typical scenarios are considered to compare and verify the system operation flexibility; Taking into account the system flexibility demand, the flexible adjustment capabilities of conventional units, battery energy storage BESS and pumped storage PHES are coordinated and optimized to ensure the balance of system flexibility supply and demand. Considering the system operation constraints, the day-ahead safety constraint unit combination and real-time economic re-dispatch model are established with the minimum total system cost, where the day-ahead dispatch time scale is 15 minutes and the real-time dispatch time scale is 5 minutes. The objective is to minimize the total cost of scheduling energy cost, standby cost and FRP call cost, and the objective function is as follows: In the formula, represents the energy cost, reserve cost and FRP call cost in day-ahead scheduling, LC RT To reduce the cost of real-time load dispatch, RC RT It is the penalty cost for abandoning wind and solar power in real-time dispatch; among which, This formula is the sum of the linearized form of the quadratic cost function of conventional units, the startup / shutdown cost of conventional units, the cost of PHES in pumping and power generation mode, and the discharge cost of BESS; in is the minimum power generation cost of unit i, u i,t is the start / stop status of the i-th unit at time t; y i,t 、z i,t are the start-up action variables and shutdown action variables of unit i, Charging power for BESS, They are the power generation energy and pumping energy of PHES respectively; In the formula, C res is the standby cost, res i,t 、res ph,t 、res be,t They are the spare capacities of conventional units, PHES, and BESS respectively; In the formula, C frp is the FRP call cost, RU i,t , R.U. ph,t , R.U. be,t They are respectively the upward flexibility capacity of conventional units, PHES, and BESS, and RD i,t , RD ph,t , RD be,t They are the downward flexibility capacities of conventional units, PHES and BESS respectively.

2. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 1, Features: In the step of considering the fluctuation of the net load of the system and establishing the upward flexibility FRU and downward flexibility FRD demand models, the FRU demand and FRD demand of the system are determined by the change of the system demand per unit time, that is, the change of the net load of the system between the next moment and the current moment; The system net load calculation formula is: NL t =L t -P s,t -P w,t In the formula, NL t is the predicted system net load value at time t; L t , P s,t , P w,t They are the system load power, photovoltaic output, and wind power output predicted at time t respectively; The specific calculation formula for FRU and FRD requirements is as follows:

3. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 2, Features: To establish a mixed integer linear programming model based on day-ahead safety-constrained unit combination and real-time economic redispatch, it is necessary to consider constraints, including conventional unit constraints, PHES model and its operation constraints, battery energy storage model constraints, new energy output constraints, day-ahead flexibility constraints and spare capacity constraints, system power flow and safety constraints, implementation flexibility constraints, and power balance constraints.

4. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 3, Features: The conventional unit constraints include upper and lower output limits of conventional units, climbing constraints, and unit operation status and start / stop status constraints; The conventional unit output upper and lower limit constraints and climbing constraints are expressed as follows: The unit operation status and start-stop status constraints are expressed as follows: yes i,t -z i,t =u i,t -u i,t-1 y i,t +z i,t ≤1 Among them, P i,t is the active power output of conventional unit i at time t, in kW; The upward and downward climbing limits of the unit, in kW / h; It is the starting and stopping climbing limit of the unit, in kW / h.

5. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 4, Features: The mathematical model of PHES and its operation constraints are as follows: In the formula, are the power generation and pumping power of PHES, respectively related to the water flow of the upper and lower reservoirs And the upper and lower reservoir heads H UR , H LR Related; η g , η m are the power generation efficiency and pumping efficiency of PHES, respectively; are the water levels of the upper and lower reservoirs respectively; ph,t is the reserve power of PHES, RU ph,t , RD ph,t Upward flexibility and downward flexibility provided to PHES.

6. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 5, Features: The battery energy storage model includes the power balance constraint, charge and discharge power limit constraint, and charge and discharge state constraint of BESS, which are as follows: In order to ensure that the charging and discharging of the energy storage battery are not performed at the same time, the following constraints are also set: ψ be,t +g be,t ≤1 In the formula, SOC be,t is the charge state of BESS; is the BESS discharge power, in kW; ψ be,t , be,t 0-1 variable for the charging and discharging working status of BESS; The energy conversion efficiency during charging and discharging of BESS; The new energy output constraints are as follows: In the formula, The available resources of photovoltaic and wind power.

7. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 6, Features: Among the day-ahead flexibility constraints and reserve capacity constraints, the constraints for conventional units, PHES, and BESS in day-ahead scheduling to meet upward / downward flexibility requirements are: In the formula, The system's day-ahead upward / downward flexibility requirements; The backup constraints of the system are: To ensure the reliability of system operation, the reserve capacity is set to 50% of the maximum output of the conventional units.

8. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 7, Features: The system power flow and safety constraints include, The transmission power Pf between node b and node n at time t b,n,t : Transmission line transmission capacity constraints: In the formula, γ b,n is the transmission line admittance; b,n is the maximum transmission capacity of the transmission line.

9. The method for dispatching a power system taking into account the flexibility of battery energy storage and pumped storage as claimed in claim 8, Features: In real-time scheduling, the FRU / FRD demand is given by the system net load calculation formula, and the system flexibility constraint in real-time redispatching is: The power balance constraint in day-ahead scheduling is: The power balance constraint in intraday scheduling is:

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