Constant power control method and system for connecting line of power distribution network and superior power grid

Abstract

The invention relates to a constant power control method and system for a tie line of a power distribution network and a superior power grid, and the method comprises the steps: obtaining the operation parameters of the power distribution network, and constructing a constant power control model of the tie line; wherein the constant power control model of the tie line is constructed by taking the sum of the operation cost of the minimum power distribution network and the operation cost of the superior power grid as an objective function; and solving the constant power control model of the tie line based on the operation parameters of the power distribution network, generating the optimal operation setting of each device in the power distribution network corresponding to the optimal transmission power of each time period of the tie line, and performing cooperative control on the devices of the power distribution network by taking the optimal operation setting as a cooperative control parameter. According to the method, the economical efficiency and the flexibility of energy interaction between the power distribution network and the superior power grid are improved, the fluctuating tie line power is controlled to be different optimal transmission power in different time periods, the objective function enables the total cost to be optimized, meanwhile, the power fluctuation of the tie line can be reduced, and the controllability and the stability of the tie line power are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric power dispatching, and in particular relates to a constant power control method and system for a tie line between a distribution network and a superior power grid. Background Art

[0002] With the global energy transition and the growing emphasis on sustainable development, the penetration of distributed renewable energy sources, such as wind and photovoltaic power generation, in power systems continues to grow rapidly. These distributed energy resources (DERs) are typically connected in large numbers to medium and low voltage distribution networks, transforming traditional distribution networks from being merely passive load networks to becoming significantly more active.

[0003] However, renewable energy sources such as wind and solar are inherently intermittent, volatile, and subject to forecasting uncertainty. Their large-scale integration poses significant challenges to the safe, stable, and economical operation of distribution networks. On the one hand, random fluctuations in DER output can cause voltage overshoots and line overloads within the distribution network. On the other hand, these fluctuations are transmitted to the upper grid via the tie lines between the distribution network and the transmission grid, increasing the upper grid's peak and frequency regulation pressures and reserve capacity requirements, impacting the operational stability of the entire grid. Effectively managing and coordinating power exchange between distribution networks containing a high proportion of DERs and the upper grid has become a key technical challenge facing power system operations.

[0004] Currently, traditional methods for controlling the power of tie lines between distribution networks and upstream power grids typically employ relatively simple strategies, such as setting a fixed tie line exchange power target over a long dispatch cycle (e.g., one hour). While simple, this "fixed power" control approach has increasingly significant drawbacks in the context of high DER integration. First, fixed power settings cannot flexibly adapt to real-time fluctuations in DER output and load within the distribution network, hindering full utilization of the distribution network's regulation capacity. This can lead to unnecessary curtailment of wind and solar power or load reduction, resulting in economic losses. Second, fixed power targets cannot effectively mitigate the impact of DER fluctuations on the upstream power grid, increasing system operational risks. Third, there is a lack of coordinated optimization of the power exchange between the distribution network's various active and reactive resources (such as conventional generators, energy storage, controllable loads, and reactive power compensation devices) and the tie line, failing to fully leverage the overall system's operational benefits.

[0005] Therefore, the existing technology still lacks a method for controlling the power of interconnecting lines that can effectively coordinate the energy interaction between the distribution network and the upper-level power grid, ensure the safe and stable operation of the system, take into account economic efficiency, and be computationally efficient and feasible. In particular, there is still much room for improvement in dealing with the problem of uncontrollable power fluctuations caused by the large-scale access of distributed power sources. Summary of the Invention

[0006] One of the purposes of the present invention is to solve at least one or more of the above-mentioned problems existing in the prior art. In other words, one of the purposes of the present invention is to provide a method and system for controlling the constant power of the connection line between a distribution network and an upper-level power grid that meets one or more of the above-mentioned requirements.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for controlling a constant power of a tie line between a distribution network and a superior power grid, comprising: Obtaining distribution network operating parameters and constructing a constant power control model for the tie line; wherein the constant power control model for the tie line is constructed with minimizing the sum of the operating costs of the distribution network and the upper-level power grid as the objective function; Solve the constant power control model of the tie line based on the distribution network operating parameters, and generate the optimal operating settings of each device in the distribution network corresponding to the optimal transmission power of the tie line in each time period; The optimal operating settings are used as collaborative control parameters to collaboratively control the distribution network equipment. As a preferred embodiment, the operating cost of the distribution network is the sum of the unit operating costs, energy storage scheduling costs, network loss costs, and the total costs of wind and solar curtailment and load shedding.

[0008] As a preferred implementation method, the objective function has constraints, which include: power balance constraints, line flow constraints, branch capacity constraints, node voltage constraints, unit output constraints, energy storage constraints, upper-level power grid power supply constraints, wind power curtailment, solar power curtailment, load shedding constraints, grouped capacitor switching constraints, static VAR compensator constraints and interconnection line power constraints in each time period.

[0009] As a further preferred implementation manner, the tie line power constraint in each time period includes a tie line power energy limit and a tie line power locking time constraint.

[0010] As a further preferred implementation manner, the constant power control model of the tie line is solved using power circle linearization and absolute value linearization methods.

[0011] As a further preferred embodiment, solving the constant power control model of the tie line based on the distribution network operation parameters specifically includes: The nonlinear formula in the constant power control model of the tie line is transformed into a linear formula by using power circle linearization and absolute value linearization methods. The distribution network operating parameters are substituted into the linear formula to solve the constant power control model of the tie line, and the optimal transmission power of the tie line between the distribution network and the upper power grid in each time period under different operating requirements is generated.

[0012] As a further preferred embodiment, converting the nonlinear formula in the constant power control model of the interconnected line into a linear formula specifically includes: In the constant power control model of the tie line, a nonlinear formula that can be linearized piecewise is selected and linearized using the power circle linearization method. The absolute value linearization method is used to linearize the absolute value in the nonlinear formula.

[0013] On the other hand, the present invention also provides a constant power control system for a tie line between a distribution network and a superior power grid, comprising: Collection terminal, used to obtain distribution network operating parameters; A collaborative control module is connected to the acquisition terminal and to the equipment of the distribution network, and can execute any of the above-mentioned constant power control methods for the tie line between the distribution network and the upper-level power grid.

[0014] On the other hand, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the program, it implements any of the above-mentioned methods for controlling the constant power of the connection line between the distribution network and the upper power grid.

[0015] On the other hand, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-mentioned methods for controlling the constant power of the tie line between the distribution network and the upper power grid.

[0016] Compared with the prior art, the method and system for controlling the constant power of the tie line between the distribution network and the upper power grid provided by the present invention have the following beneficial effects: The method and system of the present invention improve the economy and flexibility of energy interaction between the distribution network and the upper-level power grid, control the fluctuating tie-line power to different optimal transmission powers at different time periods, comprehensively consider the collaborative interaction between the distributed energy output, energy storage system, and system load in the upper-level power grid and distribution network, and tap into the comprehensive regulation potential of a new multi-objective, multi-agent power system. At the same time, the present invention uses minimizing the total cost of the upper-level power grid and distribution network as the objective function, and adopts tie-line power energy limits and tie-line power lock time constraints as constraints. This allows the total cost to be optimized while also reducing tie-line power fluctuations, enhancing the controllability and stability of tie-line power.

[0017] In addition, the method and system of the present invention use power circle linearization and large M method to linearize the nonlinear part of the model, converting the model into a definite linearized model, so that a commercial solver can be directly used for accurate solution, thereby improving the computational efficiency and practical application value of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Flowchart of a method for controlling constant power of a tie line between a distribution network and a superior power grid according to an embodiment of the present invention; Figure 2 2. It is a schematic diagram of the time window for locking the tie line power according to an embodiment of the present invention; Figure 3 1 is a schematic diagram of a linearized function image according to an embodiment of the present invention; Figure 4 It is a schematic diagram of a function image of an inscribed regular polygon according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0020] The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Changes may be made to the function and arrangement of the elements described without departing from the scope of the present invention. Various examples may appropriately omit, replace or add various processes or components. For example, the described method may be performed in an order different from the order described, and various steps may be added, omitted or combined. In addition, features described in some examples may be combined in other examples.

[0021] The embodiment of the present invention provides a method for controlling the constant power of the tie line between the distribution network and the upper power grid. Figure 1 As shown, the following steps are included: S1. Obtain the operating parameters of the distribution network and build a constant power control model for the tie line.

[0022] Before executing optimization control, it is necessary to obtain the necessary system operation information as model input. This information may include but is not limited to upper-level power grid information, distribution network topology, line parameters, load data, distributed power generation data, generator data within the distribution network, and energy storage data.

[0023] After obtaining the above parameters, a constant power control model for the tie line is constructed. This model is an optimization problem that aims to determine the optimal operation strategy for each time period in the future, such as within a day.

[0024] Among them, the constant power control model of the tie line is constructed with the objective function of minimizing the sum of the operating cost of the distribution network and the operating cost of the upper-level power grid.

[0025] Specifically, the objective function is set as ,in, is the objective function, which is divided into two parts: the operating cost of the upper power grid and the operating cost of the upper power grid. , and the operating costs of the distribution network , For the m The operating cost of a distribution network, Represents a collection of distribution networks.

[0026] Operation costs of the upper-level power grid With the following function definition: ; ; in, is the power generation cost of the upper grid, Represents a set of optimization periods; Represents the collection of upper-level power grids; and Upper power station f exist t Cost coefficients for providing active and reactive power during the time period; and Respectively t The upper power grid within the time period f Active power and reactive power generated; express t Gear position within the time period; f The number of the upper-level power grid.

[0027] Operating costs of distribution networks With the following function definition: No. m The operating cost of a distribution network is the sum of the unit operating cost, energy storage dispatching cost, network loss cost, and the total cost of wind power curtailment, solar power curtailment, and load shedding, specifically: ; in, Unit operating costs ; Total cost of wind power curtailment, solar power curtailment, and load shedding ; Energy storage dispatch costs ; Network loss costs ; In the above function, is the load shedding cost, is the cost of wind curtailment, The cost of abandoned light; Represents a set of optimization periods; Represents a collection of nodes; Represents the collection of upper-level power grids; represents a collection of generator sets; Represents a collection of fans; represents the collection of photovoltaics; represents a collection of energy storage devices; express t Generators within time period g The active power output, that is, the active power operation base point; 、 、 For generators g The operating cost coefficient; and Respectively t Generators within time period g Upward and downward spares that can be provided; 、 denote the cost of generators providing upward and downward reserves, respectively; 、 and are the penalty cost coefficients for load shedding, wind curtailment, and solar curtailment, respectively; and They are t Nodes within the period i Active and reactive load shedding capacity; and They are t Fans during the period w of wind and photovoltaic curtailment pv The amount of abandoned light; is the energy storage charging and discharging cost coefficient; and They are t Energy storage during the period e Charging power and discharging power; e The number of the energy storage device; express t The gear position within the time period.

[0028] The above objective function It also has constraints, including: power balance constraints, line flow constraints, branch capacity constraints, node voltage constraints, unit output constraints, energy storage constraints, upper-level power grid power supply constraints, wind curtailment, solar curtailment, load shedding constraints, grouped capacitor switching constraints, static VAR compensator constraints and interconnection line power constraints in each time period.

[0029] The power balance constraint is:

[0030] Where, express t Generators within time period g The active power output, that is, the active power operation base point; for t Nodes within the time period i The net load predicted active value, express t Generators within time period g The reactive power output is the reactive operation base point; express t Nodes within the time period i The net load reactive value, express t Nodes within the time period i The net load active value. Static Var Compensator svc A collection of express t Static VAR Compensator within the time period svc Reactive power provided; Indicates capacitor bank cb A collection of express t Capacitor bank within time period cb Reactive power provided; g The generator number.

[0031] The above power balance constraint ensures that in any time period, the sum of the total generator output (active or reactive) and the upper grid output (active or reactive) changes is equal to the sum of the total net load (active or reactive) changes.

[0032] The line power flow constraint is:

[0033] Where, rer is the reference node, 、 Represents time periods t Internal Line ij Active power flow and reactive power flow; loc(g)=k Representation node k Generator connected to g ; 、 Respectively represent the active power flow about the node kGeneration load transfer factors for active and reactive power injection on ; 、 Respectively represent the reactive power flow about the node k Generation load transfer factors for active and reactive power injection on ; b f It is a binary variable. When it is 1, it means the upper power grid and node k Direct connection, when it is 0, it means that the upper power grid is not connected to the node k Direct connection; loc(svc)=k Representation node k The static VAR compensator connected to the upper part; loc(cb)=k represents the capacitor bank connected to node k; for t Nodes within the time period k Generator connected to g The meritorious contribution, for t Generators within time period g The reactive power output, for t Nodes within the time period k Generator connected to g The reactive power output, for t Static VAR Compensator within the time period svc The reactive power output, for t Nodes within the time period k Static Var Compensator connected to svc The reactive power output, for t Capacitor bank within time period b The reactive power output, for t Nodes within the time period k Capacitor bank connected to cb The reactive power output, g Number the generator set. i and j are node numbers. is a collection of energy storage devices, e is the number of the energy storage device, t To optimize the time period, 、 They are active parameters and reactive parameters respectively.

[0034] Specifically,

[0035] in, ; Represents the set of branches that are not directly connected to the reference node; Represents the set of branches starting from the reference node; represents the set of branches with the reference node as the terminal node; is the active power flow relative to the node k The generation load transfer factor of active power injection on For nodes k Conductance of the connected lines, is the voltage amplitude, For nodes k The susceptance of the connected lines, is the voltage phase angle value, is the active power flow relative to the node k The generation load transfer factor for reactive power injection on is the reactive power flow relative to the node k The generation load transfer factor of active power injection on is the reactive power flow relative to the node k The generation load transfer factor for reactive power injection on For the line ij Susceptance, For the line ij conductivity.

[0036] The line flow constraint introduces a generation load transfer factor based on the decoupled linearized flow constraint of the distribution network, which more accurately expresses the relationship between the line resistance and reactance of the distribution network, can significantly reduce the error of the distribution network flow calculation, increase the reliability of the optimization results of the constant power control model of the tie line between the upper power grid and the distribution network, and improve the practical engineering value of the tie line constant power control model.

[0037] The branch capacity constraint is: ; in, Indicates a branch ij The branch capacity constraint limits the total flow on the branch to not exceed the branch capacity limit.

[0038] The upper and lower limits of node voltage are constrained as follows:

[0039]

[0040] in, and Represents nodes respectively i The upper and lower limits of the voltage amplitude; 、 Represents nodes respectively iThe upper and lower limits of the voltage phase angle; where, 、 Represents nodes respectively i The voltage amplitude of the node k Generation load transfer factor for active power and reactive power injection on ; 、 Represents nodes respectively i The voltage phase angle about the node k Generation load transfer factor for active power and reactive power injection on ; In the above formula and are the voltage amplitude related parameters and the voltage phase angle related parameters, respectively, and their expressions are as follows: ; in, 、 Represents nodes respectively i The voltage amplitude of the node k Generation load transfer factor for active power and reactive power injection on ; For nodes k Conductance of the connected lines, is the voltage amplitude value, is the voltage phase angle value, For nodes k Susceptance value of the connected line.

[0041] The middle terms of the two formulas in the node voltage upper and lower limit constraints are the node voltage amplitude and node voltage phase angle calculated based on the generation load transfer factor of the decoupled linearized power flow, both of which must be within the specified upper and lower limits.

[0042] The unit output constraint is:

[0043] Due to the limitations of the physical characteristics of the generator set, the output of the unit is limited. Indicates a generator g The active output must be within the specified upper and lower limits. Indicates that the total output of the generator should be less than the upper limit of the generator set capacity.

[0044]

[0045] This formula is the generator set g Provides upper and lower limit constraints for upward and downward backup.

[0046]

[0047] This formula is the unit gUpward ramp rate and downward ramp rate constraints.

[0048] in, and Respectively represent the units g The minimum and maximum active output values; Indicates the unit g Output capacity limit; and Respectively for units g Upward climbing capacity and downward climbing capacity; Indicates time period t duration; For the crew g The upward climbing rate, For the crew g Downward climbing rate; express t Generators within time period g The active power output, that is, the active power operation base point; express t -1 time period generator g The meritorious contribution.

[0049] The energy storage constraint is: ; in, and Represents energy storage e Maximum charging power and maximum discharging power; Indicates energy storage e In the time period t stored energy; Indicates energy storage e In the time period t-1 stored energy; and Respectively represent the charging and discharging efficiency of energy storage; and Represents energy storage e In the time period t The upper and lower limits of the energy stored in and Represent the initial energy and final energy in a charging cycle respectively. Through the above constraints, the energy storage constraint limits the change of the charging and discharging power and stored energy of the energy storage device.

[0050] The power supply constraints of the upper-level power grid are: in, Pmax f and Qmax fRespectively represent the maximum active power and reactive power provided by the upper grid f. Through the above constraints, the upper grid power supply constraint restricts the upper grid output to be within the upper and lower limits and the upper grid can absorb the active and reactive power of the distribution network.

[0051] The constraints for curtailing solar power, wind power and load shedding are: ; and They are t Time period photovoltaic pv and fan w Active power output prediction value; and They are t Time period node i Active load and reactive load; for t Time period fan w The amount of abandoned wind, for t Time period photovoltaic pv The amount of abandoned light, for t Time period node i The amount of active load abandonment, for t Time period node i The reactive load abandonment amount.

[0052] Group switching capacitors ( cb ) is constrained to: ; As a further preferred implementation manner, the tie line power constraints in each time period include tie line power energy limitations and tie line power locking time constraints.

[0053] in, Indicates capacitor bank cb The reactive power output in period t is: h Indicates gear position, Indicates that when the capacitor bank cb In gear h The number of capacitor groups put into use is a parameter; For capacitor bank cb Unit charge; To represent the capacitor bank cb exist t Is it in gear at the moment? h A 0 / 1 variable, where a value of 1 indicates that the capacitor bank cb exist t Always in gear h , otherwise it is not present; this constraint indicates thatt Time cb Can only be in one gear.

[0054] ; in, B cb,t for 0\1 Variable, when the value is 0, it means cb Maintain the original state and do not act. When the value is 1, it means cb Make adjustments; To represent the capacitor bank cb Reactive power output during the t-1 period; express cb Unit reactive power output, express t time cb The maximum number of gears that can be adjusted is Indicates the maximum number of operations of group switching capacitor banks within the optimization period.

[0055] The static VAR compensator SVC constraint is: ; in, and They represent the upper and lower limits of the static VAR compensator output respectively.

[0056] The constraints of the constant power control model of the tie line also include tie line power constraints in each time period. Specifically, the tie line power constraints in each time period include tie line power energy limit and tie line power locking time constraint.

[0057] Among them, the tie line power energy limit is: ; in, It represents the maximum total active power allowed to be exchanged between the distribution network and the upper-level power grid within a scheduling cycle; the tie line power energy limits the bidirectional power flow to be within a certain energy limit.

[0058] For the tie line power locking time constraint, first, define the tie line power planned locking time as (Unit: period), this is a parameter related to the upper power grid, indicating that once the tie line power is determined, it must be maintained at least The time period remains unchanged.

[0059] Introducing binary variables ,when When it is 1, the tie line power changes; otherwise is 0.

[0060] In order to ensure the state of the first period is reasonable, set the initial conditions It is 0 because at the beginning of the first period, the tie line power has just been established and there is no change.

[0061] In summary, the tie line power lock time constraint is: ; The meaning of this formula is that from the period To time period During this time window, the tie line power can only be changed once at most. For example, if , during the period Then, from period 3 to period 5, the number of times the tie line power changes is That is to say, during the period when the tie line power is locked, the tie line cannot change the exchange power plan arbitrarily and frequently.

[0062] The schematic diagram of the time window is as follows Figure 2 As shown, each interval should be greater than the tie line power plan locking time. On this basis, the power switching time is , are all variables to be optimized.

[0063] The above constraints adopt the tie-line power energy limit and tie-line power lock time constraint. When optimizing the total cost, the power fluctuation of the tie-line is reduced, making it flexible and controllable, and obtaining the optimal operation strategy of the upper-level power grid and distribution network, thereby ensuring that the distribution network system comprehensively considers safety, economy and reliability, and meets the requirements of safe and economical operation of the system.

[0064] After the setting of the constant power control model of the tie line is completed according to the above objective function and constraint conditions, step S2 is executed.

[0065] S2. Solve the constant power control model of the tie line based on the distribution network operating parameters to generate optimal operating settings for each device in the distribution network corresponding to the optimal transmission power of the tie line in each time period.

[0066] The core of this step is to solve the model established in S1 in combination with specific operating parameters to obtain the optimal operating strategy for each time period in the future scheduling cycle.

[0067] Because the nonlinear terms and absolute value terms in the model make direct solution very difficult, preferably, step S2 adopts power circle linearization and absolute value linearization methods to solve the constant power control model of the above-mentioned interconnection line. By adopting linearization technology, the model is converted into a mixed integer linear programming model that is easier to solve.

[0068] Specifically, step S2 includes the following steps: S21, converting the nonlinear formula in the constant power control model of the tie line into a linear formula using power circle linearization and absolute value linearization methods; This step is used to identify the part of the model that causes nonlinearity and apply the corresponding linearization technology to transform it. The nonlinear formula that can be piecewise linearized in the three-level optimization target programming model is linearized using the power circle linearization method, and then the absolute value linearization method is used to linearize the absolute value in the nonlinear formula.

[0069] This embodiment provides a specific implementation of linearization, such as Figure 3 As shown; The above constraints and It is a quadratic constraint. Step S21 uses the power circle linearization method to linearize the above constraint and solve it effectively.

[0070] The function graph of the feasible domain of the above nonlinear formula is a prototype. This week, S21 uses the power circle linearization method to approximate the creation of an inscribed regular polygon of the feasible domain of the above nonlinear formula, and uses the linear inequality that defines the boundary of the inscribed regular polygon to replace the inequality of the circle boundary, so that the original nonlinear constraints are effectively replaced by a set of linear constraints.

[0071] With constraints For example, the feasible domain of the formula is all inside the circle. In this embodiment, the circle is approximated by a regular polygon inscribed in the circle. In order to balance the accuracy and computational complexity, a polygon with more sides can usually be selected, for example, Figure 4 As shown in the figure, the area enclosed by the dodecagon inscribed in the circle is used to approximate the circular area, thereby converting the above constraints into a set of linear constraints:

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] Where, 、 and is the coefficient corresponding to the linearized power circle constraint, which varies with the number of sides of the divided regular polygon; 、 They represent the radian angles of two adjacent vertices of an equilateral u-gon inscribed in a circle; u is the number of sides of the polygon inscribed in the circle; cb Adjust the number of linearization, let the intermediate variable , Indicates the disturbance state t Capacitor bank within time period b The reactive power output, For capacitor bank cb exist t -1 time has arrived t The reactive output change value at the moment, To represent the disturbance state t- 1 Capacitor bank within a time period b Reactive output.

[0078] This embodiment also shows an example of linearization processing, for example, linearization processing is performed on the absolute value in the above-mentioned group switching capacitor constraint: The formula

[0079] The absolute value in is linearized to obtain: ; ; ; ; Among them, M is the penalty coefficient, which is infinite in principle. is an auxiliary 0\1 variable, To represent the capacitor bank cb 0\1 variable to indicate whether the action is taken. For capacitor bank cb The unit reactive power output, for t Time capacitor bank cb Maximum number of adjustable gears.

[0080] The above steps use power circle linearization and the large-M method to linearize the nonlinear part of the model, converting the model into a deterministic linearized model, which can then be accurately solved directly using a commercial solver, improving the computational efficiency and practical application value of the model.

[0081] S22. Substitute the distribution network operating parameters into the linear formula, solve the constant power control model of the interconnection line, and generate the optimal transmission power of the distribution network and the upper-level power grid interconnection line in each time period under different operating requirements.

[0082] In this step, all the specific numerical values obtained in S1 are substituted into the corresponding parameter positions in the MIP model obtained in S21, and then the solver is called to use professional mathematical optimization solver software (such as CPLEX, Gurobi, MOSEK, or open source such as SCIP, CBC, etc.) to solve this specific MIP problem instance.

[0083] The solver will find a set of values for the integer and continuous variables that satisfies all linear constraints and minimizes the objective function (total operating cost). This result set includes the optimal transmission power of the tie lines at each time period and the optimal operating settings for each device in the distribution network.

[0084] S3. Use the optimal operation settings as collaborative control parameters to collaboratively control the equipment in the distribution network.

[0085] From the complete set of results obtained from solving S2, the optimal values of all decision variables related to the controllable devices within the distribution network at each time period t are extracted. These variable values constitute the optimal operating settings. The resolved optimal operating settings are then converted into specific control instructions or set points that can be recognized and executed by the devices, thereby enabling coordinated control of the distribution network devices.

[0086] The method based on the above steps of the present invention improves the economy and flexibility of the energy interaction between the distribution network and the upper-level power grid, controls the fluctuating power of the interconnection line to different optimal transmission powers in different time periods, comprehensively considers the collaborative interaction capabilities between the distributed energy output, energy storage system and system load in the upper-level power grid and the distribution network, and taps the comprehensive regulation potential of the new multi-objective and multi-agent power system.

[0087] Another embodiment of the present invention provides a constant power control system for a tie line between a distribution network and a superior power grid, comprising: The acquisition terminal is used to obtain distribution network operating parameters. Specifically, the acquisition terminal is responsible for collecting the required operating parameters from various data sources of the distribution network in real time or periodically. This module may also include functions for cleaning, verifying, formatting, and storing the raw data for use by subsequent modules.

[0088] The collaborative control module is connected to the acquisition terminal and various devices in the distribution network. It is used to build a constant power control model for the tie line based on the distribution network operating parameters, and solve the model to generate the optimal operating settings for each device in the distribution network corresponding to the optimal transmission power of the tie line in each time period. The model is constructed with the objective function of minimizing the sum of the operating costs of the distribution network and the upper-level power grid.

[0089] The collaborative control module preferably incorporates power circle linearization and absolute value linearization algorithms, specifically using these methods to solve the constant power control model for the tie line. This ensures that the module can complete complex optimization calculations within the timescale required for engineering applications and obtain a reliable optimal solution, thereby ensuring the practicality and efficiency of the entire system.

[0090] The collaborative control module is also used to use the optimal operating settings as collaborative control parameters to collaboratively control the equipment in the distribution network and convert the optimization results into actual control actions. The system of the present invention based on the above-mentioned architecture improves the economy and flexibility of the energy interaction between the distribution network and the upper-level power grid, controls the fluctuating power of the interconnection line to different optimal transmission powers in different time periods, comprehensively considers the collaborative interaction capabilities between the distributed energy output, energy storage system and system load in the upper-level power grid and distribution network, and taps the comprehensive regulation potential of the new multi-objective and multi-agent power system.

[0091] An embodiment of the present invention further provides an electronic device, which may include but is not limited to: a processor 101, a memory 102, and an optional communication interface 103 and an input / output interface 104, etc.

[0092] The processor may be a central processing unit (CPU), a digital signal processor (DSP), a field-programmable logic device (FPGA), an application-specific integrated circuit (ASIC), or other processing core capable of executing instructions. In this embodiment, processor 101 is the control center of the electronic device, responsible for running the computer program stored in memory 102 to execute one or more steps of the "constant power control method for the tie line between a distribution network and a higher-level power grid" proposed in this invention. For example, processor 101 may calculate corresponding control instructions based on data collected from the power grid (obtained via communication interface 103 or input / output interface 104) and a preset control target (such as the target exchange power of the tie line).

[0093] Memory can be any type of volatile or non-volatile storage media, such as random access memory (RAM), read-only memory (ROM), flash memory, hard disk drive (HDD), solid-state drive (SSD), etc. Memory is used to store the operating system, various data, and computer programs.

[0094] The computer program stored in the memory, when its instructions are executed by the processor, enables the electronic device to execute the constant power control method of the tie line between the distribution network and the upper power grid of the above embodiment.

[0095] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon.

[0096] The computer program includes a series of instructions, and when these instructions are loaded and executed by the processor of the electronic device, the electronic device can implement the constant power control method of the distribution network and the upper power grid tie line of the aforementioned embodiment. It can be appreciated by those skilled in the art that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0097] The above is only an exemplary embodiment of the present disclosure and cannot be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure herein, those skilled in the art will easily think of the implementation scheme of the present disclosure. The present invention is intended to cover any variation, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the art that are not recorded in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A method for controlling constant power of a tie line between a distribution network and a higher-level power grid, characterized in that: include: Obtaining distribution network operating parameters and constructing a constant power control model for the tie line; wherein the constant power control model for the tie line is constructed with minimizing the sum of the operating cost of the distribution network and the operating cost of the upper-level power grid as the objective function; Solving the constant power control model of the tie line based on the distribution network operating parameters to generate optimal operating settings for each device in the distribution network corresponding to the optimal transmission power of the tie line in each time period; The optimal operation setting is used as a collaborative control parameter to perform collaborative control on the equipment in the distribution network.

2. A constant power control method for a tie line between a distribution network and a superior power grid according to claim 1, characterized in that: The operating cost of the distribution network is the sum of the unit operating cost, energy storage scheduling cost, network loss cost, and the total cost of wind power curtailment, solar power curtailment, and load shedding.

3. A constant power control method for a tie line between a distribution network and a superior power grid according to claim 1, characterized in that: The objective function has constraints, which include: power balance constraints, line flow constraints, branch capacity constraints, node voltage constraints, unit output constraints, energy storage constraints, upper-level power grid power supply constraints, wind power curtailment, solar power curtailment, load shedding constraints, grouped capacitor switching constraints, static VAR compensator constraints, and tie line power constraints in each time period.

4. A constant power control method for a tie line between a distribution network and a superior power grid according to claim 3, characterized in that: The tie line power constraints in each time period include tie line power energy limit and tie line power locking time constraint.

5. A constant power control method for a tie line between a distribution network and a superior power grid according to claim 1, characterized in that: The constant power control model of the tie line is solved by using power circle linearization and absolute value linearization methods.

6. A constant power control method for a tie line between a distribution network and a superior power grid according to claim 5, characterized in that: Solving the constant power control model of the tie line by the distribution network operation parameters specifically includes: The nonlinear formula in the constant power control model of the tie line is converted into a linear formula by using power circle linearization and absolute value linearization methods; The distribution network operating parameters are substituted into the linear formula, the constant power control model of the tie line is solved, and the optimal transmission power of the distribution network and the upper power grid tie line in each time period under different operating requirements is generated.

7. A constant power control method for a tie line between a distribution network and a superior power grid according to claim 6, characterized in that: Converting the nonlinear formula in the constant power control model of the tie line into a linear formula specifically includes: Selecting a nonlinear formula that can be piecewise linearized in the constant power control model of the tie line and linearizing it using a power circle linearization method; The absolute value linearization method is used to linearize the absolute value in the nonlinear formula.

8. A constant power control system for the tie line between a distribution network and a higher-level power grid, characterized in that: include: Collection terminal, used to obtain distribution network operating parameters; A collaborative control module, which is connected to the acquisition terminal and to the equipment of the distribution network, and can execute the constant power control method of the distribution network and the upper power grid tie line as described in any one of claims 1-7.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the constant power control method for the tie line between the distribution network and the upper power grid is implemented as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the constant power control method for the tie line between a distribution network and a superior power grid is implemented as described in any one of claims 1 to 7.

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