Electric-gas Energy Joint Scheduling Method and System Considering the Flexibility of Natural Gas Systems

Abstract

The present invention belongs to the technical field of energy dispatch. To solve the problem of poor ability to accurately evaluate the maximum flexible regulation capacity of the electric-gas integrated energy system, a method and system for joint dispatching of electric-gas energy considering the flexibility of the natural gas system are provided. Among them, the method for joint dispatching of electric-gas energy considering the flexibility of the natural gas system includes a quantitative model for the flexible regulation capacity of the gas storage in the natural gas network, introducing the pipeline pressure alarm value, and constructing an electric-gas joint two-stage dispatching objective function; the objective function in the first stage maximizes the wind power anti-disturbance domain, and the objective function in the second stage minimizes the system operation cost on the premise of ensuring the wind power anti-disturbance domain; under the basic operation constraints of the electric-gas integrated energy system, based on the electric-gas joint two-stage dispatching objective function, the operation base points and power adjustment amounts of each unit are determined, and the flexible regulation capacity of the gas storage in the natural gas network is quantified, which can accurately evaluate the wind power anti-disturbance domain of the system and the adjustable domain of the gas storage in the natural gas network.

Description

Technical Field

[0001] The invention belongs to the technical field of energy dispatch, and particularly relates to an electric-gas integrated energy dispatch method and system considering the flexibility of a natural gas system. Background Art

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] The randomness of renewable energy output introduces uncertain factors into the operation of the power system, bringing certain challenges to economic dispatch and also posing new requirements for the regulation ability of the system. The flexibility of the power system refers to the acceptance ability of the system to the uncertainty disturbance of the net load. At present, the flexibility resources of the power system itself are very limited, and the system operation faces great risks. The integrated energy system couples heterogeneous energies and has a certain flexible regulation potential, which can improve the flexibility regulation ability of the power system and the utilization efficiency of energy. Among them, the slow dynamic characteristics of natural gas during the flow process endow the electric-gas integrated energy system with sufficient flexible regulation ability. Therefore, considering the actual operation state of the natural gas network, fully exploring the flexible regulation ability of the natural gas network and accurately calculating the renewable energy acceptance ability of the system are of great significance for promoting the flexible and economic operation of the system and improving the new energy consumption level.

[0004] However, the current electric-gas integrated energy system has the following problems:

[0005] (1) With the deepening of the interaction degree between different energy systems, the natural gas network can provide a certain flexible operation ability for the power system. However, the existing models lack the description of the regulation interaction process between the electric-gas systems, and most of the pipeline pressure constraints of the current models only consider the safety standards and do not combine the operation flexibility requirements of the electric-gas coupled energy system, which may cause the situation that the gas network operates at the safety boundary and is difficult to provide flexibility for the next time period. To sum up, the current methods limit the accurate quantification of the flexible regulation ability of the natural gas system.

[0006] (2) In order to study the renewable energy consumption ability of the integrated energy system, the current methods take the optimal operation economy as the optimization goal and map the wind curtailment and light curtailment power into the penalty cost and add it to the optimization goal, which can promote the renewable energy consumption and improve the flexible operation level of the system to a certain extent. This single-stage optimization model equally considers the flexibility and economy of the system operation and is not conducive to accurately evaluating the maximum flexible regulation ability of the electric-gas integrated energy system. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides an electric-gas energy joint dispatching method and system considering the flexibility of the natural gas system, which can accurately evaluate the wind power anti-disturbance domain of the system and the adjustable domain of the gas storage in the natural gas network.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The first aspect of the present invention provides an electric-gas energy joint dispatching method considering the flexibility of the natural gas system.

[0010] In one or more embodiments, an electric-gas energy joint dispatching method considering the flexibility of the natural gas system includes:

[0011] Construct a quantitative model for the flexible regulation ability of the gas storage in the natural gas network according to the physical operation characteristics of the natural gas network and the interaction process between the power grid and the natural gas network;

[0012] Based on the quantitative model for the flexible regulation ability of the gas storage in the natural gas network, introduce the pipeline pressure alarm value to construct an electric-gas joint two-stage dispatching objective function; wherein, the objective function of the first stage maximizes the wind power anti-disturbance domain, and the objective function of the second stage minimizes the system operation cost on the premise of ensuring the wind power anti-disturbance domain.

[0013] Under the basic operation constraint conditions of the electric-gas integrated energy system, based on the electric-gas joint two-stage dispatching objective function, determine the operation base points and power adjustment amounts of each unit, quantify the flexible regulation ability of the gas storage in the natural gas network, and correspondingly evaluate the wind power anti-disturbance domain of the system and the adjustable domain of the gas storage in the natural gas network.

[0014] As an implementation manner, the flexible regulation ability of the gas storage in the natural gas network is characterized by the gas storage adjustment amount of the natural gas pipeline, and the adjustable domain of the gas storage in the natural gas network is the range of the gas storage adjustment amount of the natural gas pipeline.

[0015] As an implementation manner, the expression of the quantitative model for the flexible regulation ability of the gas storage in the natural gas network is:

[0016]

[0017]

[0018] Wherein, is the gas storage adjustment amount of the natural gas pipeline gl at t time period; is the gas storage adjustment amount of the natural gas pipeline gl at t -1 time period; is the adjustment value of the reference value of the inlet gas flow rate of the pipeline gl at t time period; is the pipeline gl at t the adjustment value of the reference value of the outlet gas flow rate during the period; is the gas network pipeline gl length of, is the gas network pipeline gl diameter of; is the gas constant of natural gas; is the natural gas temperature; is the gas density; is the natural gas pipeline gl at t the pressure adjustment value during the period.

[0019] As an implementation manner, in the base state scenario, the operation base points of each unit are determined according to the day-ahead prediction value of the wind power; in the disturbance scenario, considering the probability information of the wind power random disturbance, the power adjustment amount of each unit is determined.

[0020] As an implementation manner, the expression of the power adjustment amount of each unit is:

[0021]

[0022]

[0023]

[0024] In the formula: M is the set of wind farms in the system; GT is the set of gas turbines in the system; TU is the set of thermal power units in the system; NT is the set of day-ahead scheduling time scales; , are respectively t during the period, the upper and lower limits of the absorption range of the wind farm wt , which are decision variables; is t during the period, the power prediction value of the wind farm wt ; is t during the period, the participation factor of the unit i ; , are respectively t during the period, the upward and downward output power adjustment amounts of the unit i .

[0025] As an implementation manner, a new wind power anti-disturbance constraint is constructed based on the optimization result of the first stage, and then the second stage of optimization is carried out.

[0026] As an implementation manner, the basic operation constraint conditions of the electric-gas combined system include the basic constraint conditions of the power grid and the basic constraint conditions of the natural gas network;

[0027] The basic constraint conditions of the power grid include: power balance constraint under the base state scenario, flexibility demand constraint under the disturbance scenario, unit capacity constraint, unit ramp constraint, and line transmission capacity constraint;

[0028] The basic constraint conditions of the natural gas network include: gas network node flow balance constraint under the expected scenario, gas network node flow balance constraint under the disturbance scenario, and Weymouth equation.

[0029] The second aspect of the present invention provides an electric-gas energy combined dispatching system considering the flexibility of the natural gas system.

[0030] In one or more embodiments, an electric-gas energy combined dispatching system considering the flexibility of the natural gas system includes:

[0031] A model construction module, which is used to construct a quantification model of the flexible regulation ability of the gas storage in the natural gas network according to the physical operation characteristics of the natural gas network and the interaction process between the power grid and the natural gas network;

[0032] A model optimization module, which is used to introduce the pipeline pressure warning value based on the quantification model of the flexible regulation ability of the gas storage in the natural gas network to construct an electric-gas combined two-stage dispatching objective function; among them, the objective function of the first stage maximizes the wind power anti-disturbance domain, and the objective function of the second stage minimizes the system operation cost on the premise of ensuring the wind power anti-disturbance domain;

[0033] A two-stage dispatching module, which is used to decide the operation base points and power adjustment amounts of each unit based on the electric-gas combined two-stage dispatching objective function under the basic operation constraint conditions of the electric-gas integrated energy system, quantify the flexible regulation ability of the gas storage in the natural gas network, and correspondingly evaluate the wind power anti-disturbance domain of the system and the adjustable domain of the gas storage in the natural gas network.

[0034] As an implementation manner, in the model optimization module, the flexible regulation ability of the gas storage in the natural gas network is characterized by the gas storage adjustment amount of the natural gas pipeline, and the adjustable domain of the gas storage in the natural gas network is the range of the gas storage adjustment amount of the natural gas pipeline.

[0035] As an implementation manner, in the model optimization module, under the base state scenario, the operation base points of each unit are decided according to the day-ahead predicted value of the wind power; under the disturbance scenario, considering the probability information of the wind power random disturbance, the power adjustment amounts of each unit are decided.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] (1) The present invention proposes a method for quantifying the flexible regulation ability of an integrated electricity-gas energy system considering the gas network storage. It deeply analyzes the interaction mechanism between the gas system and the power system, depicts the regulation interaction process of the electricity-gas system, quantifies the flexible resources contained in the storage, and considering the actual operation scenario, sets the alarm value of the pipeline pressure, and uses the model constraint conditions to limit the pipeline pressure to fluctuate between the limit values. When the pressure is between the alarm value and the limit value, a penalty cost is set to force the pipeline pressure away from the upper and lower limits, which helps to restore the flexible regulation ability and ensure the reliable supply of natural gas, and realizes the accurate evaluation of the system's flexible regulation ability.

[0038] (2) The present invention proposes a two-stage scheduling method for the electricity-gas system based on maximizing the wind power anti-disturbance domain of the system. In the first optimization stage, the goal is to maximize the wind power anti-disturbance domain of the system, and in the second optimization stage, without reducing the wind power anti-disturbance range, the operating cost of the system is minimized. Considering the basic constraint conditions of the power system and the gas system, the operating base points and power adjustment amounts of each unit are determined, the flexible regulation ability contained in the gas network is quantified, and the wind power anti-disturbance domain of the system and the adjustable domain of the gas network are accurately evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0040] Figure 1 is a schematic flow chart of the integrated electricity-gas energy joint scheduling method considering the flexibility of the gas system in the embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of the pipeline pressure limit in the embodiment of the present invention;

[0042] Figure 3 is a schematic diagram of the electricity-gas system in the embodiment of the present invention;

[0043] Figure 4 is a schematic structural diagram of the integrated electricity-gas energy joint scheduling system considering the flexibility of the gas system in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0045] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0046] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0047] Figure 1 The flowchart of the electric-gas energy joint dispatching method considering the flexibility of the natural gas system in this embodiment is given. As Figure 1 shown, a kind of electric-gas energy joint dispatching method considering the flexibility of the natural gas system in this embodiment includes:

[0048] S100: According to the physical operation characteristics of the natural gas network and the interaction process between the power grid and the natural gas network, construct a quantitative model for the flexible regulation ability of the pipeline storage in the natural gas network;

[0049] S200: Based on the quantitative model for the flexible regulation ability of the pipeline storage in the natural gas network, introduce the pipeline pressure alarm value to construct an electric-gas joint two-stage dispatching objective function; among them, the objective function in the first stage maximizes the wind power anti-disturbance domain, and the objective function in the second stage minimizes the system operation cost on the premise of ensuring the wind power anti-disturbance domain;

[0050] S300: Under the basic operation constraints of the electric-gas integrated energy system, based on the electric-gas joint two-stage dispatching objective function, determine the operation base points and power adjustment amounts of each unit, quantify the flexible regulation ability of the pipeline storage in the natural gas network, and correspondingly evaluate the wind power anti-disturbance domain of the system and the adjustable domain of the pipeline storage in the natural gas network.

[0051] The flexibility in this embodiment refers to the ability of the power system to cope with uncertain disturbances during operation. The electric-gas integrated energy system couples heterogeneous energies, significantly improving the regulation ability of the system.

[0052] In step S100, natural gas has slow dynamic characteristics during the transmission process, which endows the pipeline with a certain energy storage capacity. The volume of natural gas stored in the pipeline is called pipeline storage, and its steady-state model is as follows:

[0053] (1)

[0054] (2)

[0055] (3)

[0056] In the formula: is the pipeline storage of the natural gas pipeline gl at t time period; is the length of the gas pipeline gl ; is the diameter of the gas pipeline gl ; is the gas constant of natural gas m; is the temperature of natural gas; is the gas density; is the pipeline gl at t the average pressure of the time period, unit bar; is the gas pipeline storage at the initial time period, is the gas pipeline storage at the end of the last scheduling period. Equation (3) indicates that the gas pipeline storage must be restored to the initial value at the end of the scheduling period; is the pipeline gl at t the reference value of the inlet gas flow rate of the time period, is the pipeline gl at t the reference value of the outlet gas flow rate of the time period.

[0057] Pipeline storage endows the natural gas system with a certain regulation ability, enabling the gas network to effectively respond to the uncertain disturbances of wind power within the anti-disturbance domain. The natural gas system provides flexibility support for the power system with the help of pipeline storage. This method defines the schedulable range of pipeline storage as the adjustable domain of pipeline storage, and the corresponding system wind power acceptance range as the wind power acceptable domain.

[0058] The storage and release of pipeline storage and the conversion of different transmission media are completed by energy coupling devices. Gas turbines are important coupling components connecting the power grid and the gas network. The flexibility supply of the natural gas system and the reserve capacity of gas turbines can be expressed by a linear relationship as:

[0059] (4)

[0060] In the formula: is the adjustment amount of the output electric power of the gas turbine at t the time period, is the adjustment amount of the gas consumed by the gas turbine at t the time period, is the conversion efficiency of the gas turbine, is the calorific value of natural gas.

[0061] Correspondingly, after the gas turbine provides reserve, the consumption or storage of pipeline storage affects the flow distribution of the gas network:

[0062] (5)

[0063] In the formula: is the gas source w at tOutput during the period, is the pipeline gl at t the reference value of the inlet gas flow rate during the period, is the adjustment value of is the pipeline gl at t the reference value of the outlet gas flow rate during the period, is the adjustment value of is the gas load flow rate of node g at t during the period; is the output electric power of the gas turbine at t during the period.

[0064] The change in flow rate will affect the operating state of the natural gas network, and the change in the operating state can be effectively addressed by the gas network storage, that is, the expression of the quantitative model for the flexible regulation ability of the gas network storage is obtained:

[0065] (6)

[0066] (7)

[0067] In the formula: is the pipeline inventory adjustment amount of the natural gas pipeline gl at t during the period; is the pressure adjustment value of the natural gas pipeline gl at t during the period.

[0068] The power adjustment of the gas turbine will cause pressure fluctuations in the gas network, affect the operating state of the gas network, and bring certain risks to the safe and stable operation of the natural gas network. In actual operation, the pipeline pressure must be restricted:

[0069] (8)

[0070] In the formula: , are respectively t the lower limit and upper limit of the pressure gl of the natural gas pipeline during the period.

[0071] In step S200, in order to prevent the gas network from operating at the pressure limit state after providing unilateral flexibility for a long time, resulting in limited adjustment ability of the pipeline in the next period, this method sets a pipeline pressure warning value, and a penalty cost will be generated when the pipeline pressure exceeds the warning range:

[0072] As Figure 2 shown, , is the pipeline pressure limit value, and its value depends on the safety operation specifications of the natural gas network; , is the pipeline pressure warning value, and its value is determined by negotiation between the electricity and natural gas operators. When the pipeline pressure is within or , a penalty cost will be generated, and the specific expression is as follows:

[0073] (9)

[0074] (10)

[0075] In the formula: is the pressure warning penalty cost of the pipeline gl , is the difference between the actual pipeline pressure and the pressure warning value, is the pressure penalty cost coefficient. When the pipeline pressure is within the interval , this item is 0; when the pipeline pressure is within the interval or , a penalty cost is generated.

[0076] In step S200, a new wind power anti-disturbance constraint is constructed based on the optimization result of the first stage, and then the second stage of optimization is carried out.

[0077] In step S300, the flexible regulation ability of the gas storage in the natural gas network is characterized by the gas storage adjustment amount of the natural gas pipeline, and the adjustable range of the gas storage in the natural gas network is the range of the gas storage adjustment amount of the natural gas pipeline.

[0078] The wind power output is uncertain, and robust optimization is a method that attempts to solve the optimal result under the "worst" scenario. Traditional robust optimization methods only consider the boundary information of uncertain quantities, and the decision results are often conservative. This method takes into account both the solution efficiency and the solution cost, and introduces the probability distribution information of uncertain quantities, as follows:

[0079] (11)

[0080] In the formula: is the probability density function of wind power random disturbance. This method assumes that it follows a normal distribution; is the actual wind power output value, which is a random variable; is the standard deviation of the random variable; is the mathematical expectation of the random variable.

[0081] When the wind power in the power system fluctuates downward, the gas network releases the stored gas, and the gas turbine increases its output to ensure the reliable supply of the power load; when the wind power fluctuates upward, the gas network stores gas, and the gas turbine reduces its output to ensure the accommodation of wind power. Due to the different operating characteristics and complex energy conversion characteristics of different energy systems, it is difficult to scientifically evaluate and optimize the flexible regulation ability of the natural gas network. Therefore, it is crucial to coordinate various flexible resources and formulate reasonable cooperation strategies to accurately quantify the regulation ability of the gas network system. Thus, the present invention proposes a joint decision-making method that takes into account both the base state and disturbance scenarios. In the base state scenario, the operating base points of each unit are determined according to the day-ahead predicted value of the wind power; in the disturbance scenario, considering the probability information of the random disturbance of the wind power, the power adjustment amount of each unit is determined.

[0082] In step S300, the expression for the power adjustment amount of each unit is:

[0083] (12)

[0084] (13)

[0085] (14)

[0086] In the formula: M is the set of wind farms in the system, GT is the set of gas turbines in the system, TU is the set of thermal power units in the system, NT is the set of day-ahead scheduling time scales; and are respectively the upper and lower limits of the accommodation range of wind farm at time period, which are decision variables; is the power prediction value of wind farm at time period, is the participation factor of unit at time period, and are respectively the upward and downward output power adjustment amounts of unit at time period.

[0087] Figure 3 is the schematic diagram of the electric-gas integrated energy system in this method, and the two energy systems are coupled through a gas turbine. The gas turbine has a relatively fast regulation rate and can suppress power disturbances on the day-ahead time scale. This method is based on the uncertain disturbance information of wind power, and the gas turbine and thermal power units are responsible for the unplanned power adjustment.

[0088] In the specific implementation process, the electro-gas combined two-stage scheduling objective function adopts a two-layer optimization objective. Assuming that the random disturbance of wind power follows a known probability distribution, a disturbance risk index of wind power is introduced in the first-layer objective. The meaning of this index is the loss of wind curtailment or load shedding in the system under the known probability distribution. When the anti-disturbance domain of wind power is the largest, this risk index is the smallest, that is:

[0089] (15)

[0090] In the formula: is the expected wind curtailment risk, is the expected load shedding risk, and the calculation method is:

[0091] (16)

[0092] (17)

[0093] In the formula: is the wind farm wt The maximum upward disturbance that may occur, is the wind farm wt The maximum downward disturbance that may occur.

[0094] Meanwhile, for a given system, when the anti-disturbance domain of wind power is the same, there may be several different setting methods for the unit operating base points and participation factors. Therefore, a second-layer objective is introduced, and minimizing the power generation cost and system operation cost is used as another basis for setting the unit operating base points and participation factors. The second-layer optimization objective function is as follows:

[0095] (18)

[0096] In the formula: Nq is the set of gas sources in the system, gline is the set of gas network pipelines in the system. 、 、 、 are the operating costs of thermal power units, the operating costs of gas turbines, the output costs of gas sources, and the penalty costs for pipeline pressure over-limit respectively.

[0097] The unit operating cost is:

[0098] (19)

[0099] (20)

[0100] In the formula: 、 and are the power generation cost coefficients of thermal power units respectively; , and are the power generation cost coefficients of the gas turbine respectively.

[0101] The gas source output cost is:

[0102] (21)

[0103] In the formula: is the gas source output cost coefficient, is t the natural gas flow rate of the gas source in the period.

[0104] The pipeline pressure limit penalty cost is:

[0105] (22)

[0106] In the formula: is the pressure limit penalty cost coefficient.

[0107] The basic operating constraint conditions of the electric-gas integrated system include the basic constraint conditions of the power grid and the basic constraint conditions of the natural gas network;

[0108] The basic constraint conditions of the power grid include: power balance constraint under the base state scenario, flexibility demand constraint under the disturbance scenario, unit capacity constraint, unit ramp constraint, and line transmission capacity constraint;

[0109] The basic constraint conditions of the natural gas network include: gas network node flow balance constraint under the expected scenario, gas network node flow balance constraint under the disturbance scenario, and the Weymouth equation.

[0110] Specifically, the gas network node flow balance constraint under the expected scenario:

[0111] (23)

[0112] In the formula: is the gas load flow of the gas network node g at t in the period, is the gas flow rate output by the P2G unit t in the period.

[0113] The gas network node flow balance constraint under the disturbance scenario:

[0114] (24)

[0115] The Weymouth equation:

[0116] In the natural gas network, the pipeline flow rate and pressure have a direct relationship, which is described by the Weymouth equation:

[0117] (25)

[0118] In the formula: sign is the sign function. When sign = 1, it indicates that the air flow is from node to node; when sign = -1, it indicates that the air flow is from node to node, where .

[0119] Power balance constraint under the base state scenario:

[0120] (26)

[0121] In the formula: is the predicted power value of the load during the period.

[0122] Flexibility demand constraint under the disturbance scenario:

[0123] (27)

[0124] (28)

[0125] (29)

[0126] Unit capacity constraint:

[0127] (30)

[0128] (31)

[0129] (32)

[0130] In the formula: and are respectively the upper and lower limits of the output of the unit.

[0131] Unit ramp constraint:

[0132] (33)

[0133] (34)

[0134] (35)

[0135] In the formula: is the maximum value of the ramp power of the unit.

[0136] Line transmission capacity constraint:

[0137] (36)

[0138] (37)

[0139] Wherein: is the number of units in the system, is the number of wind farms in the system, is the random disturbance power value of the wind farm in the time period, is the upper limit of the transmission capacity of line , represents the power flow transfer distribution factor of the unit, represents the power flow transfer distribution factor of the wind farm.

[0140] Linearization method of the objective function:

[0141] The first-layer objective function of the model contains an integral term and cannot be directly solved by the solver. Now, linearization processing is performed on it. This method adopts an improved piecewise linearization method, which can complete linearization without introducing 0-1 variables, greatly improving the solving efficiency.

[0142] This method in this embodiment assumes that the random disturbance of wind power follows a normal distribution, and the image function is symmetric about the wind power prediction value. When the wind power prediction value is = 500 MW , = 10 MW , taking the piecewise linearization method as an example, the linearization model is established as follows:

[0143] (38)

[0144] (39)

[0145] (40)

[0146] (41)

[0147] Wherein: s is the number of segments, is the slope of the th segment, is the length of the th segment, is the binary variable defined on the th segment, is the continuous variable defined on the th segment, and its value ranges from 0 to Between. After this differentiation, the curtailed wind power will definitely take values from right to left, and the 0-1 variable restricting the direction can be removed, thus transforming the linearized expression into:

[0148] (42)

[0149] (43)

[0150] (44)

[0151] Add constraints

[0152] (45)

[0153] The above new energy consumption optimization decision-making model for the integrated electricity-gas energy system has two-layer objectives. The present invention first optimizes the first-layer objective within the wind power anti-disturbance domain, and then constructs a new wind power anti-disturbance constraint with the optimization result of the first layer for the second-layer optimization. In the model, when performing the second-layer optimization, according to the optimization result of the first-layer objective, the following constraints are added:

[0154] (46)

[0155] In the formula: is the optimal objective value obtained from the first-layer optimization, and this constraint ensures that the optimization of the system operation economy will not affect the utility of new energy consumption in the first-layer optimization.

[0156] Treatment of uncertain quantities:

[0157] Formulas (36)-(37) contain uncertain parameters, which need to be processed and transformed into

[0158] (47)

[0159] (48)

[0160] That is,

[0161] (49)

[0162] (50)

[0163] Wind power random disturbance The range of

[0164] (51)

[0165] Taking formula (49) as an example, considering The coefficient of There are two cases of positive and negative values, and equation (49) is transformed into (52)-(53):

[0166] (52)

[0167] (53)

[0168] Similarly, it can be known that equation (50) can be transformed

[0169] (54)

[0170] (55)

[0171] So far, equations (36)-(37) are expressed as equations (52)-(55).

[0172] In Figure 4 gives a schematic diagram of the structure of an electric-gas integrated energy dispatch system considering the flexibility of the natural gas system, as Figure 4 shown, an electric-gas integrated energy dispatch system considering the flexibility of the natural gas system includes:

[0173] A model construction module 401, which is used to construct a quantitative model for the flexible regulation ability of the gas storage in the natural gas network according to the physical operation characteristics of the natural gas network and the interaction process between the power grid and the natural gas network;

[0174] A model optimization module 402, which is used to introduce the pipeline pressure alarm value based on the quantitative model for the flexible regulation ability of the gas storage in the natural gas network to construct an electric-gas combined two-stage dispatch objective function; among them, the objective function of the first stage maximizes the wind power anti-disturbance domain, and the objective function of the second stage minimizes the system operation cost on the premise of ensuring the wind power anti-disturbance domain;

[0175] A two-stage dispatch module 403, which is used to decide the operation base point and power adjustment amount of each unit based on the electric-gas combined two-stage dispatch objective function under the basic operation constraints of the electric-gas integrated energy system, quantify the flexible regulation ability of the gas storage in the natural gas network, and correspondingly evaluate the wind power anti-disturbance domain of the system and the adjustable domain of the gas storage in the natural gas network.

[0176] In the specific implementation process, in the model optimization module 403, the flexible regulation ability of the gas storage in the natural gas network is characterized by the gas storage adjustment amount of the natural gas pipeline, and the adjustable domain of the gas storage in the natural gas network is the range of the gas storage adjustment amount of the natural gas pipeline.

[0177] In the model optimization module 403, under the base state scenario, the operation base point of each unit is decided according to the day-ahead predicted value of the wind power; under the disturbance scenario, considering the probability information of the wind power random disturbance, the power adjustment amount of each unit is decided.

[0178] It should be noted here that each module in the combined power-gas energy dispatching system considering the flexibility of the natural gas system corresponds one by one to each step in the above-mentioned combined power-gas energy dispatching method considering the flexibility of the natural gas system, and the specific implementation process is the same, so it will not be elaborated here.

[0179] Among them, Figure 1 The computer program instructions corresponding to the method shown can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the process Figure 1 one process or multiple processes and / or blocks Figure 1 the functions specified in one block or multiple blocks.

[0180] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0181] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for joint dispatching of electricity and gas energy taking into account the flexibility of the natural gas system, characterized in that: include: According to the physical operation characteristics of the natural gas network and the interaction process between the power grid and the natural gas network, a quantitative model of the flexible regulation capacity of the natural gas network is constructed; Based on the quantitative model of the flexible regulation capacity of natural gas network, the pipeline pressure alarm value is introduced to construct the two-stage dispatch objective function of electricity-gas joint; the objective function of the first stage maximizes the wind power anti-disturbance domain, and the objective function of the second stage minimizes the system operation cost under the premise of ensuring the wind power anti-disturbance domain; Among them, the pipeline storage gives the natural gas system the ability to adjust, so that the gas grid can effectively deal with the uncertain disturbances of wind power within the anti-disturbance domain; the natural gas system uses the pipeline storage to provide flexibility support for the power system, and defines the dispatchable range of the pipeline storage as the pipeline storage adjustable domain, and the corresponding system wind power acceptance range as the wind power acceptance domain; , is the pipeline pressure limit, and its value depends on the safe operation specifications of the natural gas network; , is the pipeline pressure alarm value, which is determined by the power and natural gas operators through negotiation; when the pipeline pressure exceeds the alarm range, that is, when the pipeline pressure is or The expression for the penalty cost when within the range is: Where: For pipeline gl The pressure warning penalty cost, is the difference between the actual pressure of the pipeline and the pressure alarm value. is the pressure penalty cost coefficient; when the pipeline pressure is in the interval When the pipeline pressure is within the interval or When , penalty costs are incurred; In the base state scenario, the operating base point of each unit is determined based on the day-ahead wind power forecast value; in the disturbance scenario, the power adjustment amount of each unit is determined by considering the probability information of random disturbances of wind power; The expression of power adjustment of each unit is: Where: M is the collection of wind farms in the system; GT is the collection of gas turbines in the system; TU is the collection of thermal power units in the system; NT is the set of day-ahead scheduling time scales; , They are t Wind farm wt The upper and lower limits of the absorption range are the decision quantities; for t Wind farm wt The power prediction value of for t Time unit i The participation factor of , They are t Time unit i Upward and downward output power adjustment; The objective function of the first stage is to maximize the wind power anti-disturbance domain. When the wind power anti-disturbance domain is the largest, the risk index is the smallest, and the expression is: Where: To anticipate the risk of wind curtailment, is the expected load shedding risk, calculated as: Where: For wind farms wt The maximum upward disturbance that may occur, For wind farms wt The maximum downward disturbance that may occur, for Wind farm The power prediction value, , They are Wind farm The upper and lower limits of the absorption range, is the probability density function of wind power random disturbance; The objective function of the second stage is to minimize the system operation cost under the premise of ensuring the wind power anti-disturbance domain: Where: NT is the set of day-ahead scheduling time scales, TU is the collection of thermal power units in the system, GT is the collection of gas turbines in the system, Nq is the collection of gas sources in the system, gline is the collection of gas network pipelines in the system. , , , They are the operating cost of thermal power units, the operating cost of gas turbines, the gas source output cost, and the penalty cost for exceeding the pipeline pressure limit; Under the basic operating constraints of the electricity-gas integrated energy system, the operating base point and power adjustment amount of each unit are determined based on the electricity-gas joint two-stage scheduling objective function, and the flexible regulation capacity of the natural gas grid is quantified, corresponding to the evaluation system wind power anti-disturbance domain and the natural gas grid regulation domain; The electric-gas energy joint dispatch method taking into account the flexibility of the natural gas system analyzes the interaction mechanism between the natural gas system and the electric power system, characterizes the adjustment interaction process of the electric-gas system, quantifies the flexibility resources contained in the pipeline storage, and considers the actual operation scenario. It sets the alarm value of the pipeline pressure and uses model constraints to limit the fluctuation of the pipeline pressure between the limit values. When the pressure is between the alarm value and the limit value, a penalty cost is set to force the pipeline pressure to stay away from the upper and lower limits, which is helpful to restore the flexible adjustment capacity and the reliable supply of natural gas, and realize the accurate evaluation of the system's flexible adjustment capacity.

2. The method for joint dispatching of electricity and gas energy taking into account the flexibility of the natural gas system according to claim 1, characterized in that: The flexible regulation capability of the pipeline storage of the natural gas network is characterized by the pipeline storage adjustment amount of the natural gas pipeline, and the pipeline storage adjustable domain of the natural gas network is the range of the pipeline storage adjustment amount of the natural gas pipeline.

3. The method for joint dispatching of electricity and gas energy taking into account the flexibility of the natural gas system as claimed in claim 2, characterized in that: The expression of the quantitative model of the pipeline storage flexible adjustment capacity of the natural gas network is: in, For natural gas pipelines gl exist t The amount of inventory adjustment for the time period; For natural gas pipelines gl exist t -1 period of inventory adjustment; For pipeline gl exist t An adjustment value of a reference value of an inlet gas flow rate for a time period; For pipeline gl exist t The adjustment value of the baseline value of the outlet gas flow rate during the time period; For gas network pipeline gl Length, For gas network pipeline gl The diameter of is the gas constant of natural gas; is the natural gas temperature; is the gas density; For natural gas pipelines gl exist t The pressure adjustment value for the time period.

4. The method for joint dispatching of electricity and gas energy taking into account the flexibility of the natural gas system according to claim 1, characterized in that: The new wind power anti-disturbance constraints are constructed based on the optimization results of the first stage, and then the second stage of optimization is carried out.

5. The method for joint dispatching of electricity and gas energy taking into account the flexibility of the natural gas system according to claim 1, characterized in that: The basic operating constraints of the electricity-gas combined system include basic constraints of the power grid and basic constraints of the natural gas grid; The basic constraints of the power grid include: power balance constraints in base state scenarios, flexibility demand constraints in disturbance scenarios, unit capacity constraints, unit ramp constraints and line transmission capacity constraints; The basic constraints of the natural gas network include: gas network node flow balance constraints under expected scenarios, gas network node flow balance constraints under disturbance scenarios and the Weymouth equation.

6. An electricity-gas energy joint dispatching system taking into account the flexibility of the natural gas system, characterized in that: include: A model building module, which is used to build a quantitative model of the pipeline storage and flexible adjustment capability of the natural gas network based on the physical operation characteristics of the natural gas network and the interaction process between the power grid and the natural gas network; The model optimization module is used to quantify the flexible adjustment capacity model of pipeline storage based on the natural gas network, introduce the pipeline pressure alarm value, and construct the two-stage dispatch objective function of electricity-gas joint; among which, the objective function of the first stage maximizes the wind power anti-disturbance domain, and the objective function of the second stage minimizes the system operation cost under the premise of ensuring the wind power anti-disturbance domain; Among them, the pipeline storage gives the natural gas system the ability to adjust, so that the gas grid can effectively deal with the uncertain disturbances of wind power within the anti-disturbance domain; the natural gas system uses the pipeline storage to provide flexibility support for the power system, and defines the dispatchable range of the pipeline storage as the pipeline storage adjustable domain, and the corresponding system wind power acceptance range as the wind power acceptance domain; , is the pipeline pressure limit, and its value depends on the safe operation specifications of the natural gas network; , is the pipeline pressure alarm value, which is determined by the power and natural gas operators through negotiation; when the pipeline pressure exceeds the alarm range, that is, when the pipeline pressure is or The expression for the penalty cost when within the range is: Where: For pipeline gl The pressure warning penalty cost, is the difference between the actual pressure of the pipeline and the pressure alarm value. is the pressure penalty cost coefficient; when the pipeline pressure is in the interval When the pipeline pressure is within the interval or When , penalty costs are incurred; In the base state scenario, the operating base point of each unit is determined based on the day-ahead wind power forecast value; in the disturbance scenario, the power adjustment amount of each unit is determined by considering the probability information of random disturbances of wind power; The expression of power adjustment of each unit is: Where: M is the collection of wind farms in the system; GT is the collection of gas turbines in the system; TU is the collection of thermal power units in the system; NT is the set of day-ahead scheduling time scales; , They are t Wind farm wt The upper and lower limits of the absorption range are the decision quantities; for t Wind farm wt The power prediction value of for t Time unit i The participation factor of , They are t Time unit i Upward and downward output power adjustment; The objective function of the first stage is to maximize the wind power anti-disturbance domain. When the wind power anti-disturbance domain is the largest, the risk index is the smallest, and the expression is: Where: To anticipate the risk of wind curtailment, is the expected load shedding risk, calculated as: Where: For wind farms wt The maximum upward disturbance that may occur, For wind farms wt The maximum downward disturbance that may occur, for Wind farm The power prediction value, , They are Wind farm The upper and lower limits of the absorption range, is the probability density function of wind power random disturbance; The objective function of the second stage is to minimize the system operation cost under the premise of ensuring the wind power anti-disturbance domain: Where: NT is the set of day-ahead scheduling time scales, TU is the collection of thermal power units in the system, GT is the collection of gas turbines in the system, Nq is the collection of gas sources in the system, gline is the collection of gas network pipelines in the system. , , , They are the operating cost of thermal power units, the operating cost of gas turbines, the gas source output cost, and the penalty cost for exceeding the pipeline pressure limit; The two-stage dispatch module is used to determine the operating base point and power adjustment amount of each unit based on the two-stage dispatch objective function of the electricity-gas combined energy system under the basic operating constraints of the electricity-gas integrated energy system, quantify the flexible regulation capability of the natural gas grid, and evaluate the wind power anti-disturbance domain of the system and the adjustable domain of the natural gas grid; The electricity-gas energy joint dispatching system that takes into account the flexibility of the natural gas system analyzes the interaction mechanism between the natural gas system and the power system, characterizes the adjustment interaction process of the electricity-gas system, quantifies the flexibility resources contained in the pipeline storage, and considers the actual operation scenario. It sets the alarm value of the pipeline pressure and uses model constraints to limit the fluctuation of the pipeline pressure between the limit values. When the pressure is between the alarm value and the limit value, a penalty cost is set to force the pipeline pressure to stay away from the upper and lower limits, which is conducive to the recovery of flexible adjustment capabilities and the reliable supply of natural gas, and realizes an accurate assessment of the system's flexible adjustment capabilities.

7. The electric-gas energy joint dispatching system taking into account the flexibility of the natural gas system as claimed in claim 6, characterized in that: In the model optimization module, the pipeline storage flexible adjustment capability of the natural gas network is characterized by the pipeline storage adjustment amount of the natural gas pipeline, and the pipeline storage adjustable domain of the natural gas network is the range of the pipeline storage adjustment amount of the natural gas pipeline.

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