Method for coordinated transmission and distribution dispatching of power grids in electricity market environment, and system

Abstract

The present invention relates to the technical field of electricity markets. Disclosed are a method for coordinated transmission and distribution dispatching of power grids in an electricity market environment, and a system. The method comprises: collecting transmission and distribution data of power grids, and performing economic dispatch modeling for a hybrid system incorporating hydropower and thermal power; performing linear processing on nonlinear terms in a model; and using Benders decomposition to accelerate the solution of the model, and optimizing coordinated transmission and distribution dispatching of the power grids. In the method of the present invention, by means of performing economic dispatch modeling for the hybrid system incorporating hydropower and thermal power, the power system's ability to integrate renewable energy is enhanced, improving the resource utilization efficiency; by means of converting complex nonlinear terms in an original model into linear expressions, the model is easier to solve, providing rapid response capabilities for power grid dispatching; and by using a Benders decomposition method to accelerate the solution, a problem is decomposed into a master problem and a sub-problem, which are solved independently, thus improving the overall solving efficiency, scalability and flexibility.

Description

A method and system for coordinated dispatching of power grid transmission and distribution in an electric power market environment Technical Field

[0001] The present invention relates to the technical field of power market, and in particular to a method and system for coordinated dispatching of power grid transmission and distribution in a power market environment. Background Art

[0002] With the continuous deepening of power market reform, the power system's approach to absorbing renewable energy needs to be innovated. Traditional non-market-based absorption methods can no longer meet the development needs of today's green power system. Exploring market-based absorption methods is an inevitable choice for further promoting the vigorous development of renewable energy. The integration of large-scale renewable energy generation into the grid squeezes the output of traditional thermal power units, significantly reducing the system's backup resources. This significantly reduces the system's ability to regulate power balance, making it difficult to cope with the scheduling risks brought about by renewable energy with uncertain power output values. At the same time, as distributed resources are connected to the distribution network, the distribution system's operating mode is more flexible and diverse. The distribution network is becoming increasingly proactive and market-oriented, making the interaction between transmission and distribution networks closer and greatly increasing the flexibility and controllability of the distribution network. The traditional organizational model of the separated transmission and distribution network cannot fully leverage the decisive role of the market in resource allocation. To better achieve economic dispatch of the power system under a market environment, it is necessary to establish coordinated dispatch of power grid transmission and distribution under the power market. Through the coordinated operation of the transmission and distribution power systems, the distribution system provides a series of ancillary services to the transmission system, making the transmission system more efficient, flexible and safe.

[0003] To address these shortcomings, we first collected grid transmission and distribution data and conducted economic dispatch modeling for a hybrid system containing hydropower and thermal power, effectively combining the advantages of renewable energy and traditional energy. Compared with existing technologies, this method provides a more reasonable dispatching strategy for the effective access and utilization of renewable energy. In model processing, the nonlinear terms in the model are linearized, which effectively reduces the computational complexity and improves the solution efficiency. In addition, Benders decomposition is used to accelerate the solution of the model, further optimizing the efficiency of grid transmission and distribution coordinated dispatch. These innovations not only improve the economy and safety of the power system, but also enhance the system's adaptability to the uncertainty of renewable energy. Through innovative methods of grid transmission and distribution coordinated dispatch, the shortcomings of existing technologies in large-scale grid connection of renewable energy, grid resource dispatch and market-based absorption are effectively addressed, providing new solutions for the sustainable development of the power system. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: the existing transmission and distribution network scheduling method has low efficiency, low flexibility and high complexity, and how to make the transmission system operate more efficiently, more flexibly and safely.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a method for coordinated dispatching of power grid transmission and distribution in an electricity market environment, comprising collecting power grid transmission and distribution data, performing economic dispatch modeling for a hybrid system containing hydropower and thermal power; linearizing the nonlinear terms in the model; and accelerating the solution of the model using Benders decomposition to optimize the coordinated dispatching of power grid transmission and distribution.

[0007] As a preferred solution of the grid transmission and distribution coordinated scheduling method in the power market environment described in the present invention, the grid transmission and distribution data includes power generation data, grid data, market data and environmental data; power generation data includes reservoir water level, fuel consumption rate, generator set efficiency and emission efficiency; grid data includes real-time load data, line loss and line impedance; market data includes real-time electricity price; environmental data includes temperature, humidity and precipitation.

[0008] As a preferred solution of the grid transmission and distribution coordinated dispatching method in the power market environment described in the present invention, the economic dispatch modeling includes an optimization objective of minimizing the total system operation cost, and the total system operation cost includes the coal consumption cost of the thermal power station operation cost, the start-up and shutdown cost of the thermal power station operation cost, and the water abandonment cost of the hydropower station, which is expressed as:

[0009] Among them, F is the objective function of minimizing the total cost of system operation, i and N are the number and total number of thermal power units, j and M are the number and total number of cascade hydropower stations, t and T are the time period number and total number, P i,t is the output of the i-th thermal power unit in period t, u i,t is the state variable of the unit, 0 indicates the unit is in shutdown state, 1 indicates the unit is in startup state, C i,t represents the startup cost of unit i in period t, S j,t represents the amount of water abandoned by hydropower station j in period t, λ j is the penalty factor for water abandonment of the hydropower station, and the abandoned water volume is converted into the abandoned water cost. The operating cost f of computer group i in period t is i (p i,t ) is expressed as:

[0010] Among them, a, b, and c are the consumption characteristic parameters of the unit operation.

[0011] As a preferred solution of the method for coordinated dispatching of power grid transmission and distribution in the power market environment described in the present invention, the economic dispatch modeling also includes a hybrid system containing hydropower and thermal power, and constraining the system includes calculating system power constraints and spinning reserve constraints. The power balance of the power system is the balance of power supply and demand. The total power generation of the power system is balanced with the total load of the distribution network connected to the active network. The power balance constraint is modeled and expressed as follows:

[0012] Among them, P i,t 、P j,t Denote the output of thermal power unit i and hydropower station j in time period t, D t It represents the algebraic sum of the equivalent loads of different distribution networks in time period t. When distributed generation is connected to the distribution network, the distribution network changes from a passive network to an active network. When the active network is calculated and analyzed, if there are too many distributed generation in the distribution network, the equivalent load is negative. The spinning reserve constraint is calculated and expressed as:

[0013] Among them, P i,max 、P j,max They represent the output limits of thermal power unit i and hydropower station j, respectively, t represents the system's reserve capacity factor in time period t; establish unit operation constraints including unit output constraints, ramp constraints, and minimum start-stop time constraints; the computer unit output constraint is expressed as:

[0014] Among them, P i,min 、P j,min denote the lower output limits of thermal power unit i and hydropower station j respectively; the ramp constraint is calculated and expressed as:

[0015] Among them, R i,max is the upper limit of the ramp constraint of thermal power unit i, R j,max represents the upper limit of the ramp constraint of hydropower station j; the minimum start-stop time constraint is calculated as:

[0016] Among them, T on 、T off They are the minimum running time and the minimum stopping time of the unit, T i,t Indicates the continuous operation time or continuous shutdown time of unit i in period t; the constraints of the hydropower station include water balance constraint, head constraint, power flow constraint, outflow flow constraint, water level constraint, and water level-reservoir capacity and unit output relationship constraint; the water balance constraint is calculated as:

[0017] Among them, V j,t is the storage capacity of power station j in period t, Ij,t is the inflow flow of power station j in period t, Q j,t is the outflow flow of power station j in period t, is the kth direct upstream power station of power station j at t-τ j,k Outbound flow in the period, K j is the set of power stations directly upstream of power station j, τ j,k is the water flow delay time from power station j to upstream power station k, q j,t is the power generation flow of power station j in period t, s j,t is the water discharge of power station j in period t; the calculation head constraint is expressed as:

[0018] Among them, h j,t , Z j,t 、 are respectively the generating head, water level and head loss of power station j in period t. There is a nonlinear relationship between head loss and generating flow. The generating flow constraint, outflow flow constraint and water level constraint are expressed as:

[0019] Among them, q jt is the lower limit of power generation flow of power station j in period t, is the upper limit of power generation flow of power station j in period t, Q j,t is the lower limit of the outflow flow of power station j in period t, is the upper limit of the outflow flow of power station j in period t, Z j,t is the lower limit of the water level of power station j in period t, is the upper limit of the water level of power station j in period t; the constraint of calculating the relationship between water level, reservoir capacity and unit output is expressed as:

[0020] Among them, f j,v (V j,t ) represents the nonlinear relationship between the water level and reservoir capacity of each hydropower station, f j,q,h (q j,t ,h j,t ) represents the two-dimensional relationship between the output of power station j and the power generation flow and water head.

[0021] As a preferred solution of the grid transmission and distribution coordinated scheduling method under the power market environment described in the present invention, the linearization processing includes linearizing the objective function of the model, the objective function includes the thermal power operation cost and the hydropower abandonment penalty cost, the coal consumption cost in the thermal power operation cost is a quadratic function of the unit output, and the coal consumption cost is a nonlinear function of the unit output. The linearized output is expressed as:

[0022] Among them, m, Mmax are the linearization segment number and the total number of segments, k i,m is the slope of the mth segment of the linearized operating cost curve of thermal power unit i, P i,t,m is the output of unit i in the mth segment during period t, ΔP i,t is the power difference of the average segment.

[0023] As a preferred solution of the method for coordinated dispatching of power grid transmission and distribution in the power market environment described in the present invention, wherein: the row linearization processing also includes linearizing the constraints with nonlinear relationships,

[0024] The water level-storage capacity and head loss-power generation flow are one-dimensional nonlinear relationships. In the water level and storage capacity function, by introducing 0-1 variables, the nonlinear function is linearly interpolated. The linearized model is expressed as:

[0025] in, They represent the water level and storage capacity segmentation points of the water level and storage capacity curve of power station j respectively. The numerical correspondence of the segmentation points is based on historical data. j It is expressed as the lower limit of storage capacity of power station j, It is represented as the upper limit of storage capacity of power station j, represents the value of the storage capacity of power station j in the kth interval during period t, is a 0-1 indicator variable, representing whether the storage capacity of power station j in period t is in the kth discrete interval, 1 means it is in the interval, and 0 means it is not in the interval;

[0026] The output constraint of the hydropower unit is a two-dimensional nonlinear constraint. The reservoir capacity and power generation flow are discretized into n and m segments respectively. The average value of the upper and lower limits of each reservoir capacity segment is taken as the interval reservoir capacity of the segment. For a specific reservoir capacity interval, the unit output is simplified to a unary function of the power generation flow, and the linear relationship is calculated by segmented interpolation.

[0027] As an optimal solution of the method for coordinated dispatching of power grid transmission and distribution in the power market environment described in the present invention, the accelerated solution of the model using Benders decomposition includes decomposing the original problem into main and sub-problems based on model linearization, alternately solving the main and sub-problems, and calculating the optimal solution. The main problem is a unit combination problem without safety constraints, and the sub-problem is a system flow verification.

[0028] When the objective function value of the time period subproblem is less than the threshold, the solution of the main problem satisfies the power flow equation and operation constraints of time period t, and the subproblem is a feasible subproblem.

[0029] When the objective function value of the sub-problem in a time period is greater than or equal to the threshold, the solution to the main problem does not satisfy the power flow equation and operation constraints of the time period t, and the sub-problem is an infeasible sub-problem. For the infeasible sub-problem, the limit-crossing information is fed back to the main problem, and the solution to the main problem in the corresponding time period is corrected. During the correction process, Benders decomposition is performed, which is expressed as:

[0030] in, are the forward and reverse power flow relaxations of line l, respectively, p,i ,λ u,i are the Lagrange multipliers for the unit output constraint and the start-stop state constraint, are the values ​​of the upper iteration respectively. Based on the decomposed model, the transmission and distribution coordinated scheduling optimization of the power grid is carried out.

[0031] Another object of the present invention is to provide a power grid transmission and distribution coordinated scheduling system in an electricity market environment, which can solve the problem of low accuracy in the current transmission and distribution network scheduling by linearizing the nonlinear terms in the model and linearizing the model objective function and nonlinear relationship constraints.

[0032] As an optimal solution for the grid transmission and distribution coordinated dispatching system in the power market environment described in the present invention, it includes: an economic dispatching module, a linearization processing module, and a decomposition optimization module; the economic dispatching module is used to collect grid transmission and distribution data and perform economic dispatch modeling for a hybrid system containing hydropower and thermal power; the linearization processing module is used to linearize the nonlinear terms in the model and linearize the model objective function and nonlinear relationship constraints; the decomposition optimization module is used to accelerate the solution of the model using Benders decomposition to perform grid transmission and distribution coordinated dispatching optimization.

[0033] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement a step of a method for coordinated dispatching of power grid transmission and distribution in an electricity market environment.

[0034] A computer-readable storage medium stores a computer program, wherein the computer program is executed by a processor to implement the steps of a method for coordinated dispatching of power grid transmission and distribution in an electricity market environment.

[0035] Beneficial effects of the present invention: The grid transmission and distribution coordinated dispatching method provided by the present invention in the power market environment performs economic dispatch modeling for a hybrid system containing hydropower and thermal power, comprehensively considers the characteristics of different energy types and their respective operating costs, thereby enhancing the power system's ability to integrate renewable energy and improving resource utilization efficiency; by converting complex nonlinear terms in the original model into linear expressions, the model is made easier to solve while retaining the core characteristics of the original model, providing a rapid response capability for grid dispatching; by adopting the Benders decomposition method for accelerated solution, the problem is decomposed into a main problem and sub-problems, which can be solved independently, thereby improving the overall solution efficiency as well as scalability and flexibility. The present invention achieves better results in terms of accuracy, efficiency and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of 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 work.

[0037] FIG1 is an overall flow chart of a method for coordinated dispatching of power grid transmission and distribution in a power market environment provided by the first embodiment of the present invention.

[0038] FIG2 is a piecewise linearized diagram of the hydropower conversion relationship of a grid transmission and distribution coordinated scheduling method in an electricity market environment provided by the first embodiment of the present invention.

[0039] FIG3 is a flowchart of a Benders decomposition solution to a grid dispatching method for coordinated dispatching of grid transmission and distribution in a power market environment provided by the first embodiment of the present invention.

[0040] FIG4 is a 118-node unit output diagram of a grid transmission and distribution coordinated scheduling method in an electricity market environment provided by a second embodiment of the present invention.

[0041] FIG5 is an overall flow chart of a power grid transmission and distribution coordinated dispatching system in a power market environment provided by a third embodiment of the present invention. DETAILED DESCRIPTION

[0042] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0043] Example 1

[0044] 1 to 3 , an embodiment of the present invention provides a method for coordinated dispatching of power grid transmission and distribution in a power market environment, including:

[0045] S1: Collect grid transmission and distribution data and conduct economic dispatch modeling for hybrid systems containing hydropower and thermal power.

[0046] Furthermore, grid transmission and distribution data includes power generation data, grid data, market data, and environmental data; power generation data includes reservoir water levels, fuel consumption rates, generator efficiency, and emission efficiency; grid data includes real-time load data, line loss, and line impedance; market data includes real-time electricity prices; and environmental data includes temperature, humidity, and precipitation.

[0047] It should be noted that the optimization objective of economic dispatch modeling is to minimize the total system operating cost. The total system operating cost includes the coal consumption cost of the thermal power station operation cost, the start-up and shutdown cost of the thermal power station operation cost, and the water abandonment cost of the hydropower station, which can be expressed as:

[0048] Among them, F is the objective function of minimizing the total cost of system operation, i and N are the number and total number of thermal power units, j and M are the number and total number of cascade hydropower stations, t and T are the time period number and total number, P i,t is the output of the i-th thermal power unit in period t, u i,t is the state variable of the unit, 0 indicates the unit is in shutdown state, 1 indicates the unit is in startup state, C i,t represents the startup cost of unit i in period t, S j,t represents the amount of water abandoned by hydropower station j in period t, λ j is the penalty factor for water abandonment of the hydropower station, and the abandoned water volume is converted into the abandoned water cost. The operating cost f of computer group i in period t is i (p i,t ) is expressed as:

[0049] Among them, a, b, and c are the consumption characteristic parameters of the unit operation.

[0050] It should also be noted that economic dispatch modeling also includes hybrid systems containing hydropower and thermal power. System constraints include calculating system power constraints and spinning reserve constraints. The power balance of the power system is the balance of power supply and demand. The total power generation of the power system is balanced with the total load of the distribution network connected to the active network. The power balance constraint is modeled and expressed as:

[0051] Among them, P i,t 、P j,t Denote the output of thermal power unit i and hydropower station j in time period t, Dt It represents the algebraic sum of the equivalent loads of different distribution networks in time period t. When distributed generation is connected to the distribution network, the distribution network changes from a passive network to an active network. When the active network is calculated and analyzed, if there are too many distributed generation in the distribution network, the equivalent load is negative. The spinning reserve constraint is calculated and expressed as:

[0052] Among them, P i,max 、P j,max They represent the output limits of thermal power unit i and hydropower station j, respectively, t represents the system's reserve capacity factor in time period t; establish unit operation constraints including unit output constraints, ramp constraints, and minimum start-stop time constraints; the computer unit output constraint is expressed as:

[0053] Among them, P i,min 、P j,min denote the lower output limits of thermal power unit i and hydropower station j respectively; the ramp constraint is calculated and expressed as:

[0054] Among them, R i,max is the upper limit of the ramp constraint of thermal power unit i, R j,max represents the upper limit of the ramp constraint of hydropower station j; the minimum start-stop time constraint is calculated as:

[0055] Among them, T on 、T off They are the minimum running time and the minimum stopping time of the unit, T i,t Indicates the continuous operation time or continuous shutdown time of unit i in period t; the constraints of the hydropower station include water balance constraint, head constraint, power flow constraint, outflow flow constraint, water level constraint, and water level-reservoir capacity and unit output relationship constraint; the water balance constraint is calculated as:

[0056] Among them, V j,t is the storage capacity of power station j in period t, I j,t is the inflow flow of power station j in period t, Q j,t is the outflow flow of power station j in period t, is the kth direct upstream power station of power station j at t-τ j,k Outbound flow in the period, K j is the set of power stations directly upstream of power station j, τ j,k is the water flow delay time from power station j to upstream power station k, q j,t is the power generation flow of power station j in period t, s j,t is the water discharge of power station j in period t; the calculation head constraint is expressed as:

[0057] Among them, h j,t , Z j,t 、 are respectively the generating head, water level and head loss of power station j in period t. There is a nonlinear relationship between head loss and generating flow. The generating flow constraint, outflow flow constraint and water level constraint are expressed as:

[0058] Among them, q j,t is the lower limit of power generation flow of power station j in period t, is the upper limit of power generation flow of power station j in period t, Q j,t is the lower limit of the outflow flow of power station j in period t, is the upper limit of the outflow flow of power station j in period t, Z j,t is the lower limit of the water level of power station j in period t, is the upper limit of the water level of power station j in period t; the constraint of calculating the relationship between water level, reservoir capacity and unit output is expressed as:

[0059] Among them, f j,v (V j,t ) represents the nonlinear relationship between the water level and reservoir capacity of each hydropower station, f j,q,h (q j,t ,h j,t ) represents the two-dimensional relationship between the output of power station j and the power generation flow and water head.

[0060] It should also be noted that economic dispatch modeling integrates the operating characteristics of thermal and hydropower stations, minimizing the operating costs of the power system. This helps to optimize resource allocation and improve the economy and efficiency of the power system. By adjusting the output of thermal power units, the operating costs of thermal power stations can be effectively managed, especially in terms of consumption characteristic parameters and start-up and shutdown costs. Reasonable control of abandoned water volume and cost evaluation can help optimize the operation of hydropower stations and reduce resource waste.

[0061] S2: Linearize the nonlinear terms in the model.

[0062] Furthermore, the linearization process includes linearizing the objective function of the model. The objective function includes the thermal power operation cost and the water abandonment penalty cost of hydropower. The coal consumption cost in the thermal power operation cost is a quadratic function of the unit output, and the coal consumption cost is a nonlinear function of the unit output. The linearized output is expressed as:

[0063] Among them, m, M max are the linearization segment number and the total number of segments, k i,m is the slope of the mth segment of the linearized operating cost curve of thermal power unit i, Pi,t,m is the output of unit i in the mth segment during period t, ΔP i,t is the power difference of the average segment.

[0064] It should be noted that the linearization process also includes linearization of nonlinear relationship constraints. Water level-storage capacity and head loss-power flow are one-dimensional nonlinear relationships. In the water level and storage capacity function, by introducing 0-1 variables, the nonlinear function is linearly interpolated. The linearized model is expressed as follows:

[0065] in, They represent the water level and storage capacity segmentation points of the water level and storage capacity curve of power station j respectively. The numerical correspondence of the segmentation points is based on historical data. j It is expressed as the lower limit of storage capacity of power station j, It is represented as the upper limit of storage capacity of power station j, represents the value of the storage capacity of power station j in the kth interval during period t, is a 0-1 indicator variable, representing whether the storage capacity of power station j in time period t is in the kth discrete interval, 1 indicates that it is in the interval, and 0 indicates that it is not in the interval; the output constraint of the hydropower unit is a two-dimensional nonlinear constraint. By discretizing the storage capacity and power generation flow into n and m segments respectively, the average of the upper and lower limits of the storage capacity of each segment is taken as the interval storage capacity of the segment. For a specific storage capacity interval, the unit output is simplified to a unary function of the power generation flow, and the linear relationship is calculated by piecewise interpolation.

[0066] It should also be noted that, referring to the piecewise linearized hydropower conversion relationship diagram in Figure 2, the introduction of 0-1 variables for linear interpolation in the one-dimensional nonlinear relationship between water level-reservoir capacity and head loss-power generation flow can transform the complex hydropower station operation model into an easy-to-handle linear model, which makes it possible to optimize the operation of the hydropower station and improves the flexibility and accuracy of hydropower station management. For the two-dimensional nonlinear constraints on the output of the hydropower unit, linearization is achieved through discretization and piecewise interpolation, which greatly simplifies the calculation process of output scheduling and improves the accuracy and operability of scheduling.

[0067] S3: Benders decomposition is used to accelerate the solution of the model and optimize the coordinated scheduling of power grid transmission and distribution.

[0068] Furthermore, the model is accelerated by using Benders decomposition, which includes decomposing the original problem into main and sub-problems based on model linearization, solving the main and sub-problems alternately, and calculating the optimal solution. The main problem is the unit combination problem without safety constraints, and the sub-problem is the system flow verification.

[0069] When the objective function value of the time period subproblem is less than the threshold, the solution of the main problem satisfies the power flow equation and operation constraints of time period t, and the subproblem is a feasible subproblem.

[0070] When the objective function value of the sub-problem in a time period is greater than or equal to the threshold, the solution to the main problem does not satisfy the power flow equation and operation constraints of the time period t, and the sub-problem is an infeasible sub-problem. For the infeasible sub-problem, the limit-crossing information is fed back to the main problem, and the solution to the main problem in the corresponding time period is corrected. During the correction process, Benders decomposition is performed, which is expressed as:

[0071] in, are the forward and reverse power flow relaxations of line l, respectively, p,i ,λ u,i are the Lagrange multipliers for the unit output constraint and the start-stop state constraint, are the values ​​of the upper iteration respectively. Based on the decomposed model, the transmission and distribution coordinated scheduling optimization of the power grid is carried out.

[0072] It should be noted that, referring to Figure 3, Benders decomposition solves the power grid dispatching flow chart, and the Benders decomposition method is used to accelerate the solution of the model. Through model transformation, the constructed model can be solved by the existing solver, but when the system scale increases, the time required increases exponentially. In order to speed up the solution, Benders decomposition is used for accelerated processing.

[0073] It should also be noted that the alternating solution method of the main and sub-problems not only simplifies the calculation process, but also gradually approaches the optimal solution through continuous iterative optimization, ensuring the accuracy and reliability of the solution results. When the objective function value of the sub-problem is lower than the preset threshold, it means that the current solution meets the power system's flow equation and operation constraints and is feasible. When the objective function value is higher than the threshold, the solution to the main problem needs to be corrected. The Benders cut applied in this correction process provides an effective feedback mechanism, ensuring the safety and stability of the power system operation. The optimization of the entire process improves the adaptability and flexibility of the power system in complex operating environments, which has important practical significance for the power market and power system operation, and improves the economy of resource allocation and the reliability of system operation.

[0074] Example 2

[0075] 4 , which shows an embodiment of the present invention, provides a method for coordinated dispatching of power grid transmission and distribution in an electricity market environment. To verify the beneficial effects of the present invention, scientific demonstration is conducted through economic benefit calculations and simulation experiments.

[0076] First, the IEEE118-node system includes 48 thermal power units and 6 hydropower units. The transmission network is responsible for supplying power to 91 distribution systems. In addition to the accelerated solution of the Benders decomposition, an unaccelerated solution was also performed. That is, only the grid transmission and distribution data was collected. Economic dispatch modeling was performed for the hybrid system containing hydropower and thermal power. The nonlinear terms in the model were linearized.

[0077] Reference Table 1 lists the comparison of the two solution methods in terms of solution speed and accuracy.

[0078] Table 1 Comparative analysis of two methods

[0079] Figure 4 shows the output diagram of the 118-node unit without Benders decomposition (left) and with Benders decomposition (right). The operating cost is based on the results of the traditional method.

[0080] The Benders decomposition method decomposes the unit commitment problem into two problems: a main problem and a subproblem. The main problem is used to solve the optimal unit commitment, without considering system flow constraints; the subproblem is used to perform system flow verification. For infeasible solutions to the main problem, a Benders feasibility cut containing system slack and Lagrange multipliers is returned to the main problem. The main problem is then re-solved to obtain a new unit commitment, and the system flow verification is then re-performed. Through iteration, when the slack of the subproblem is sufficiently small, the optimal unit commitment is obtained. Although the Benders decomposition method requires iteration, the scale of both the main problem and the subproblem is smaller than the original problem, so the solution speed is accelerated. As the system scale increases, the acceleration effect becomes more obvious. From the perspective of operating cost, compared with direct solution, the operating cost of the Benders decomposition method is partially improved. That is, the improvement in calculation speed of the Benders decomposition method is at the expense of calculation accuracy. Compared with the existing technology, our invention is creative and novel, especially in improving the operating efficiency of the power system and reducing costs. Therefore, our invention is creative.

[0081] Example 3

[0082] 5 , which shows an embodiment of the present invention, a grid transmission and distribution coordinated dispatching system in an electricity market environment is provided, including an economic dispatching module, a linearization processing module, and a decomposition optimization module.

[0083] The economic dispatch module is used to collect grid transmission and distribution data and perform economic dispatch modeling for hybrid systems containing hydropower and thermal power. The linearization processing module is used to linearize the nonlinear terms in the model and linearize the model objective function and nonlinear relationship constraints. The decomposition optimization module is used to accelerate the solution of the model using Benders decomposition and perform coordinated dispatch optimization of grid transmission and distribution.

[0084] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, and other media that can store program code.

[0085] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0086] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0087] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having logic gate circuits for implementing logical functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc. It should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to be limiting. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications should be encompassed by the claims of the present invention.

[0088] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. 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 coordinated dispatching of power grid transmission and distribution in an electric power market environment, characterized in that: include: Collect power grid transmission and distribution data and conduct economic dispatch modeling for hybrid systems containing hydropower and thermal power; Linearize the nonlinear terms in the model; Benders decomposition is used to accelerate the solution of the model and optimize the coordinated dispatching of power grid transmission and distribution.

2. The method for coordinated dispatching of power grid transmission and distribution in a power market environment according to claim 1, characterized in that: The power grid transmission and distribution data includes power generation data, power grid data, market data and environmental data; Power generation data include reservoir levels, fuel consumption rates, generator unit efficiency, and emissions efficiency; Grid data includes real-time load data, line loss, and line impedance; Market data includes real-time electricity prices; Environmental data includes temperature, humidity, and precipitation.

3. The method for coordinated dispatching of power grid transmission and distribution in a power market environment according to claim 2, characterized in that: The economic dispatch modeling includes the optimization goal of minimizing the total system operation cost. The total system operation cost includes the coal consumption cost of the thermal power plant operation cost, the start-up and shutdown cost of the thermal power plant operation cost, and the water abandonment cost of the hydropower station, which is expressed as: Among them, F is the objective function of minimizing the total cost of system operation, i and N are the number and total number of thermal power units, j and M are the number and total number of cascade hydropower stations, t and T are the time period number and total number, P i,t is the output of the i-th thermal power unit in period t, u i,t is the state variable of the unit, 0 indicates the unit is in shutdown state, 1 indicates the unit is in startup state, C i,t represents the startup cost of unit i in period t, S j,t represents the amount of water abandoned by hydropower station j in period t, λ j is the penalty factor for water abandonment in hydropower stations, converting the amount of abandoned water into the cost of abandoned water. The operating cost of computer group i in period t is f i (p i,t ) is expressed as: Among them, a, b, c are the consumption characteristic parameters of the unit operation.

4. The method for coordinated dispatching of power grid transmission and distribution in a power market environment according to claim 3, characterized in that: The economic dispatch modeling also includes a hybrid system containing hydropower and thermal power, and the system constraints include calculating the system power constraints and the spinning reserve constraints. The power balance of the power system is the balance of power supply and demand. The total power generation of the power system is balanced with the total load of the distribution network connected to the active network. The power balance constraint is modeled and expressed as: Among them, P i,t , P j,t Denote the output of thermal power unit i and hydropower station j in time period t, respectively. t It represents the algebraic sum of the equivalent loads of different distribution networks in time period t. When distributed generation is connected to the distribution network, the distribution network changes from a passive network to an active network. When the active network is calculated and analyzed, if there are too many distributed generation in the distribution network, the equivalent load is negative; Calculate the spinning reserve constraint, expressed as: Among them, P i,max , P j,max They represent the upper limits of the output of thermal power unit i and hydropower station j, respectively, t represents the reserve capacity factor of the system in time period t; Establish unit operation constraints including unit output constraints, ramp constraints and minimum start and stop time constraints; The computer group output constraint is expressed as: Among them, P i,min , P j,min They represent the lower limits of the output of thermal power unit i and hydropower station j respectively; The climbing constraint is calculated and expressed as: Among them, R i,max is the upper limit of the ramp constraint of thermal power unit i, R j,max represents the upper limit of the ramp constraint of hydropower station j; The minimum start-stop time constraint is calculated as: Among them, T on , T off They are the minimum running time and the minimum stopping time of the unit, T i,t Indicates the continuous running time or continuous shutdown time of unit i in period t; Establish hydropower station constraints including water balance constraints, head constraints, power generation flow constraints, outflow flow constraints, water level constraints, and water level-reservoir capacity and unit output relationship constraints; The water balance constraint is expressed as: Among them, V j,t is the storage capacity of power station j in period t, I j,t is the inflow flow of power station j in time interval t, Q j,t is the outflow flow of power station j in period t, is the kth direct upstream power station of power station j at t-τ j,k The outbound flow rate of the period, K j is the set of power stations directly upstream of power station j, τ j,k is the water flow delay time from power station j to upstream power station k, q j,t is the power generation flow of power station j in period t, s j,t is the water discharge of power station j in period t; The computational head constraint is expressed as: Among them, h j,t , Z j,t , are the power generation head, water level and head loss of power station j in period t, respectively. There is a nonlinear relationship between head loss and power generation flow; The calculation of power generation flow constraints, outflow flow constraints and water level constraints is expressed as: Among them, q j,t is the lower limit of power generation flow of power station j in period t, is the upper limit of power generation flow of power station j in period t, Q j,t is the lower limit of the outflow flow of power station j in period t, is the upper limit of the outflow flow of power station j in period t, Z j,t is the lower limit of the water level of power station j in period t, is the upper limit of the water level of power station j in period t; The constraint of calculating the relationship between water level, reservoir capacity and unit output is expressed as: Among them, f j,v (V j,t ) represents the nonlinear relationship between the water level and reservoir capacity of each hydropower station, f j,q,h (q j,t ,h j,t ) represents the two-dimensional relationship between the output of power station j and the power generation flow and water head.

5. The method for coordinated dispatching of power grid transmission and distribution in a power market environment according to claim 4, characterized in that: The linearization process includes linearizing the objective function of the model. The objective function includes the thermal power operation cost and the water abandonment penalty cost of hydropower. The coal consumption cost in the thermal power operation cost is a quadratic function of the unit output. The coal consumption cost is a nonlinear function of the unit output. The linearized output is expressed as: Among them, m, M max are the linearization segment number and the total number of segments, respectively, i,m is the slope of the mth segment of the linearized operating cost curve of thermal power unit i, P i,t,m is the output of unit i in the mth segment during period t, ΔP i,t is the power difference of the average segment.

6. The method for coordinated dispatching of power grid transmission and distribution in a power market environment according to claim 5, characterized in that: The row linearization process also includes linearizing the existence of nonlinear relationship constraints; Water level-storage capacity and head loss-power generation flow are one-dimensional nonlinear relationships. In the water level and storage capacity function, by introducing 0-1 variables, the nonlinear function is linearly interpolated. The linearized model is expressed as: in, They represent the water level and storage capacity segmentation points of the water level and storage capacity curve of power station j respectively. The numerical correspondence of the segmentation points is based on historical data. j It is represented as the lower limit of the storage capacity of power station j, is the upper limit of the storage capacity of power station j, represents the value of the storage capacity of power station j in the kth interval during time period t, is a 0-1 indicator variable, representing whether the storage capacity of power station j in period t is in the kth discrete interval, 1 means it is in the interval, and 0 means it is not in the interval; The output constraint of the hydropower unit is a two-dimensional nonlinear constraint. The reservoir capacity and power generation flow are discretized into n and m segments respectively, and the average value of the upper and lower limits of each reservoir capacity is taken as the interval reservoir capacity of the segment. For a specific reservoir capacity interval, the unit output is simplified to a univariate function of the power generation flow, and the linear relationship is calculated by piecewise interpolation.

7. The method for coordinated dispatching of power grid transmission and distribution in a power market environment according to claim 6, characterized in that: The accelerated solution of the model by using Benders decomposition includes decomposing the original problem into main and sub-problems based on model linearization, solving the main and sub-problems alternately, and calculating the optimal solution, wherein the main problem is a unit commitment problem without safety constraints, and the sub-problem is a system power flow verification; When the objective function value of the time period subproblem is less than the threshold, the solution of the main problem satisfies the power flow equation and operation constraints of the time period t, and the subproblem is a feasible subproblem; When the objective function value of the time period sub-problem is greater than or equal to the threshold, the solution of the main problem does not satisfy the power flow equation and operation constraints of the t period, and the sub-problem is an infeasible sub-problem. For the infeasible sub-problem, the limit-crossing information is fed back to the main problem, and the solution of the main problem of the corresponding period is corrected. During the correction process, Benders decomposition is performed, which is expressed as: in, are the forward power flow relaxation and reverse power flow relaxation of line l, λ p,i , u,i are the Lagrange multipliers of the unit output constraint and the start-stop state constraint, are the values ​​of the upper iteration respectively. Based on the decomposed model, the coordinated dispatching optimization of power grid transmission and distribution is carried out.

8. A system using the coordinated dispatching method for power grid transmission and distribution in a power market environment as claimed in any one of claims 1 to 7, characterized in that: Including economic scheduling module, linearization processing module, decomposition optimization module; The economic dispatch module is used to collect power grid transmission and distribution data and to perform economic dispatch modeling for a hybrid system containing hydropower and thermal power; The linearization processing module is used to linearize the nonlinear terms in the model and linearize the model objective function and nonlinear relationship constraints; The decomposition optimization module is used to accelerate the solution of the model using Benders decomposition to optimize the coordinated dispatching of power grid transmission and distribution.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for coordinated dispatching of power grid transmission and distribution in the power market environment described in any one of claims 1 to 7 are implemented.

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 steps of the method for coordinated dispatching of power grid transmission and distribution in an electric power market environment described in any one of claims 1 to 7 are implemented.

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