Unit Commitment Method for Coupled Frequency Security Constraints of Electric Power and Natural Gas Systems

Abstract

An embodiment of the present invention provides a method for unit commitment with frequency security constraints for coupling power and natural gas systems. The method includes: establishing a power system operating cost minimization objective function corresponding to the frequency security-constrained unit commitment; constructing frequency security constraints; constructing power system operating constraints; constructing natural gas system operating constraints; constructing power system and natural gas system coupling constraints; and determining the optimal operating state of the unit commitment based on the power system operating cost minimization objective function, the frequency security constraints, the power system operating constraints, the natural gas system operating constraints, and the power system and natural gas system coupling constraints. The method considers the impact of the natural gas system operating constraints and the power system and natural gas system coupling constraints on the power system frequency security-constrained units, optimizes the power system operating cost objective function under the specified constraints, and minimizes the power system operating cost.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power system operation and scheduling, and in particular to a unit combination method with frequency safety constraints for coupling of power and natural gas systems. Background Art

[0002] As environmental concerns become increasingly prominent, traditional synchronous thermal power units in power systems are being replaced by high-proportion renewable energy sources such as wind and solar. Because wind and solar power are connected to the power system via power electronics, they generally lack inertia, leading to a gradual decrease in the inertia of the power system. This necessitates considering frequency security in the unit mix. Meanwhile, the development and deployment of gas-fired units provides flexibility for wind and solar renewable energy sources, but this also exacerbates the coupling between the power system and the natural gas system.

[0003] Changes in the natural gas system's state directly impact the startup and shutdown, output, and operation of gas-fired units, as well as the power system's operational status. For example, a gas shortage can reduce the output of gas-fired units or even shut them down, impacting the power system's operational status. Existing research on frequency-constrained unit commitments has been conducted solely from the perspective of the power system, neglecting the impact of coupling with other energy systems, such as the natural gas system. Currently, research on frequency-constrained unit commitments that considers the coupling of power and natural gas systems is lacking. Summary of the Invention

[0004] The embodiments of the present invention propose a method, apparatus, computer equipment, and storage medium for frequency-safety-constrained unit combination for coupling of power and natural gas systems, which are suitable for studying frequency-safety-constrained unit combination for coupling of power and natural gas systems while considering the impact of the natural gas system on the coupling.

[0005] In a first aspect, an embodiment of the present invention provides a unit commitment method for coupling frequency safety constraints of electric power and natural gas systems, comprising:

[0006] Establish the objective function of minimizing the power system operation cost corresponding to the unit commitment with frequency security constraints;

[0007] Construct frequency safety constraints;

[0008] Constructing power system operation constraints;

[0009] Establishing natural gas system operation constraints;

[0010] Construct coupling constraints between the power system and the natural gas system;

[0011] The optimal operating state of the unit combination is determined according to the power system operation cost minimization objective function, the frequency security constraint, the power system operation constraint, the natural gas system operation constraint, and the power system and natural gas system coupling constraint.

[0012] In a second aspect, an embodiment of the present invention further provides a unit combination device for power and natural gas system coupling frequency safety constraints, comprising:

[0013] An objective function establishment module is used to establish an objective function for minimizing the power system operation cost corresponding to the unit commitment with frequency security constraints;

[0014] Frequency safety constraint building module, used to build frequency safety constraints;

[0015] Power system operation constraint construction module, used to construct power system operation constraints;

[0016] A natural gas system operation constraint building module, used to build natural gas system operation constraints;

[0017] Power system and natural gas system coupling constraint construction module, used to construct power system and natural gas system coupling constraints;

[0018] An optimal operating state determination module is used to determine the optimal operating state of the unit combination based on the power system operation cost minimization objective function, the frequency security constraints, the power system operation constraints, the natural gas system operation constraints, and the power system and natural gas system coupling constraints.

[0019] In a third aspect, an embodiment of the present invention further provides a computer device, comprising:

[0020] one or more processors;

[0021] a memory for storing one or more programs,

[0022] When the one or more programs are executed by the one or more processors, the one or more processors implement the unit combination method with frequency security constraints for coupling of electric power and natural gas systems as described in the first aspect.

[0023] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the unit combination method for frequency safety constraints of coupling of power and natural gas systems as described in the first aspect.

[0024] In an embodiment of the present invention, an objective function for minimizing the operating cost of the power system corresponding to the frequency security-constrained unit combination is established; frequency security constraints are constructed; power system operating constraints are constructed; natural gas system operating constraints are constructed; and power system and natural gas system coupling constraints are constructed. The optimal operating state of the unit combination is determined based on the power system operating cost minimization objective function, frequency security constraints, natural gas system operating constraints, power system and natural gas system coupling constraints, and power system and natural gas system coupling constraints. This method considers the impact of natural gas system operating constraints and power system and natural gas system coupling constraints on power system frequency security-constrained units, optimizes the power system operating cost objective function under specified constraints, and minimizes the operating cost of the power system. This method can provide insights into operational analysis in the context of coupling power systems with other energy systems, and has both theoretical value and practical significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of a unit combination method for coupling frequency safety constraints of electric power and natural gas systems provided in the first embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of a unit combination device with frequency safety constraints for coupling of electric power and natural gas systems provided in the second embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the structure of a computer device provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0029] Example 1

[0030] Figure 1 This is a flow chart of a method for frequency-safety-constrained unit commitment for coupling power and natural gas systems, provided in Example 1 of the present invention. This embodiment is applicable to studying frequency-safety-constrained unit commitment for coupling power and natural gas systems, taking into account the impact of the natural gas system on coupling. The method can be performed by a unit commitment device for frequency-safety-constrained unit commitment for coupling power and natural gas systems. The unit commitment device for frequency-safety-constrained unit commitment for coupling power and natural gas systems can be implemented by software and / or hardware and can be configured in a computer device, such as a server, personal computer, embedded computer, etc., and specifically includes the following steps:

[0031] Step 101: Establish an objective function for minimizing the power system operation cost corresponding to the frequency security constrained unit commitment.

[0032] The unit commitment theory in the power market refers to arranging power generation plans at the lowest cost within a certain scheduling cycle to achieve balance with the given load and meet certain constraints and reserve requirements.

[0033] The present invention mainly focuses on how to set the system operating parameters under some self-defined constraints to minimize the operating cost of the power system and at the same time ensure the safety of the power system operation and good performance of the system.

[0034] In some embodiments of the present invention, the power system operation cost minimization objective function is:

[0035]

[0036] Where T represents the set of time periods; G and N represent the sets of gas-fired units and non-gas-fired units; and is the starting and stopping cost of generator set i; is the no-load cost of generator set i; c i is the marginal generation cost of generator i; is the standby cost of generator set i; and are the start and stop states of generator set i at time t; x i,t is the operating status of generator set i at time t; P i,t and R i,t is the power output and reserve of generator set i at time t.

[0037] Step 102: Construct frequency safety constraints.

[0038] Frequency safety constraints primarily involve establishing constraints on three indicators: the frequency change rate, the lowest frequency, and the quasi-steady-state frequency. These constraints include system data set according to requirements and the operating parameters of the optimal solution that minimizes the objective function.

[0039] In some embodiments of the present invention, step 102 includes:

[0040] Step 1021: Construct frequency change rate constraint:

[0041]

[0042] Among them, H t is the inertia of the system at time t; and P imax are the inertia constant and capacity of generator set i respectively; f0 is the rated frequency; ΔP t dis is the power disturbance of the system at time t; RoCoF max is the maximum allowed frequency change rate.

[0043] Step 1022: Construct the frequency minimum point constraint:

[0044]

[0045] Among them, κ t It is the only solution of the following formula (4);

[0046]

[0047] Among them, T d is the transfer time; D is the load damping rate; P t D is the total load level at time t; Δf DB is the dead time of the generator set speed governor; Δf max is the maximum allowed frequency deviation.

[0048] Step 1023: Construct quasi-steady-state frequency constraints:

[0049]

[0050] in, is the maximum allowable quasi-steady-state frequency deviation.

[0051] The system is always in steady state when it is not disturbed. Quasi-steady state means that after the system is disturbed, it responds, such as generator output, so that the system reaches a short-term new equilibrium.

[0052] For example, some operating parameters in the frequency security constraint condition will affect the result of the power system operation cost minimization objective function. For example, the inertia H of the system at time t t , the operating status x of generator set i at time t i,t , and the power reserve R of generator set i at time t i,t .

[0053] It should be noted that the embodiment of the present invention constructs the frequency safety constraint by constructing the above-mentioned frequency change rate constraint, frequency minimum point constraint and quasi-steady-state frequency constraint conditions, which is an exemplary description of the present invention. In other embodiments of the present invention, other constraint conditions can also be constructed to construct the frequency safety constraint.

[0054] Step 103: Construct power system operation constraints.

[0055] Some operating parameter settings during the operation of the power system will affect the results of the objective function of minimizing the operating cost of the power system.

[0056] In some embodiments of the present invention, the power system operation constraints are:

[0057]

[0058]

[0059]

[0060]

[0061] x i,t P i min ≤P i,t ≤x i,t P i max (10)

[0062]

[0063] -RD i ≤P i,t +R i,t -P i,t-1 -R i,t-1 ≤RU i (12)

[0064]

[0065]

[0066] Among them, formula (6) describes the logical relationship between the generator set state and the start-stop state; formula (7) uses binary variables to describe the generator set state, start state and shutdown state;

[0067] Among them, formula (8) and formula (9) are the minimum operation time limit constraint and the minimum shutdown time limit constraint respectively, formula (10) is the generator output constraint, formula (11) is the standby output constraint, formula (12) is the generator set climbing constraint, formula (13) is the line transmission power constraint, and formula (14) is the system active power balance constraint;

[0068] Where, T i on and T i off are the minimum operating time and minimum shutdown time of generator set i respectively; P i min is the lower limit of the output of generator set i; is the spare capacity of generator set i; RD i and RU i are the downward and upward climbing limits of generator set i respectively; F l max is the transmission capacity of transmission line l; ψ l,i is the transfer factor of generator set i to transmission line l; is the load d e Transfer factor for transmission line l; is the load d at time t e Level; D e A collection of loads.

[0069] It should be noted that the embodiment of the present invention constructs the power system operation constraints by constructing the above-mentioned power system operation constraints, which is an exemplary description of the present invention. In other embodiments of the present invention, other constraints can also be constructed to construct the power system operation constraints.

[0070] Step 104: Construct natural gas system operation constraints.

[0071] Some operating parameter settings during the operation of the natural gas system will affect the results of the objective function of minimizing the operating cost of the power system.

[0072] In some embodiments of the present invention, the natural gas system operation constraints are:

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] Among them, formula (16) is used to calculate the average airflow in the pipeline; formula (17) is the pipeline airflow equation; formula (18) describes the relationship between the pipeline storage and the pressure of the two end nodes; formula (22) is used to calculate the air flow consumed by the compressor;

[0085] Among them, formula (15) is the node airflow balance equation constraint; formula (19) is the pipe inventory relationship constraint between time t and time t-1; formula (20) is the total pipe inventory constraint at the end of the scheduling period is not less than the initial pipe inventory constraint; formula (21) is the air flow constraint through the compressor; formula (23) is the compressor boost ratio constraint; formula (24) is the air source output constraint; formula (25) is the node pressure constraint;

[0086] Where, S(m), G(m), D g L(m) and C(m) are the gas source set, gas generator set, gas load set and compressor set connected to node m respectively; g is a collection of pipelines; is the output of gas source s at time t; is the gas flow consumed by the gas generator set g at time t; is the gas load d g The value at time t; is the air flow consumed by compressor k at time t; is the air flow through compressor k at time t; F mn,t is the gas flow rate of pipeline mn at time t; and are the inlet and outlet gas flows of pipeline mn at time t; C mn and K mn are all constant parameters of pipeline mn; π m,t and π n,t are the pressures on nodes m and n at time t; L mn,t is the pipe inventory of pipeline mn at time t; is the maximum capacity allowed to pass through compressor k; is the gas consumption ratio of compressor k; and The upper limit and lower limit of the compressor boost ratio respectively; and The maximum and minimum output limits of gas source s respectively; and are the upper and lower limits of the pressure on node m respectively.

[0087] For example, the output of gas source s at time t is The gas flow consumed by the gas generator set g at time t Gas load d g The value at time t The air flow consumed by compressor k at time t The air flow through compressor k at time t The gas flow F in pipe mn at time t mn,t , respectively, the inlet and outlet gas flow rates of pipeline mn at time t and The pressure π on node m and node n at time t m,t and π n,t , and the pipeline inventory L of pipeline mn at time t mn,t ,The setting of the above working parameters will affect the results of the objective function of minimizing the ,operation cost of the power system.

[0088] It should be noted that the embodiment of the present invention constructs the natural gas system operation constraints by constructing the above-mentioned natural gas system operation constraints, which is an exemplary description of the present invention. In other embodiments of the present invention, other constraints can also be constructed to construct the natural gas system operation constraints.

[0089] Step 105: Construct coupling constraints between the power system and the natural gas system.

[0090] Some operating parameter settings in the coupling of power system and natural gas system will affect the results of the objective function of minimizing the operating cost of the power system.

[0091] In some embodiments of the present invention, the coupling constraint conditions between the power system and the natural gas system are:

[0092]

[0093] Where, is the energy conversion coefficient of the gas turbine unit; P g,t and R g,t are the output and reserve of gas generator set g at time t respectively.

[0094] For example, P g,t and R g,t The output and reserve settings of the gas generator set g at time t will affect the result of the objective function of minimizing the operating cost of the power system.

[0095] It should be noted that the embodiment of the present invention constructs the coupling constraint of the power system and the natural gas system by constructing the above-mentioned coupling constraint conditions of the power system and the natural gas system. This is an exemplary illustration of the present invention. In other embodiments of the present invention, other constraints can also be constructed to construct the coupling constraint of the power system and the natural gas system.

[0096] In some embodiments of the present invention, the unit commitment method for coupling frequency security constraints of electric power and natural gas systems further includes:

[0097] Step 106: By introducing auxiliary variables, formula (3) is transformed into a mixed integer linear programming constraint to obtain a new frequency minimum point constraint condition:

[0098]

[0099] -Mx i,t ≤X i,t ≤Mx i,t (28)

[0100]

[0101] Among them, in formula (27) to formula (29), X i,t is an auxiliary variable introduced; M is a preset large positive number.

[0102] Since the frequency minimum point constraint equation (3) constructed in step 1022 contains bilinear terms, and the frequency safety constraint unit commitment model composed of various constraints and the objective function is a mixed integer nonlinear nonconvex model, it is difficult to solve directly. Therefore, variable substitution and the big M method are used to convert equation (3) into a mixed integer linear programming constraint. Among them, the big M method is a method for finding an initial basis feasible solution for the constraints of the linear programming problem when the constraints are (=) equality or (≥) greater than type, after using the artificial variable method, treating M as an algebraic symbol to participate in the operation, and solving it using the simplex method.

[0103] By transforming Equation (3) into Equations (27)-(29), the non-convex constraints that are difficult to solve are transformed into mixed integer linear programming constraints, which greatly improves the convenience of the constraints and can be easily solved by existing optimization toolkits, while also improving the efficiency of the solution.

[0104] The embodiments of the present invention are only examples and are not limiting.

[0105] Step 107: Perform convex relaxation transformation on equation (19) to obtain the convex second-order cone constraint of the pipe storage relationship between time t and time t-1:

[0106]

[0107] Since the pipe storage relationship constraint (19) between time t and time t-1 constructed in step 103 is a quadratic equality non-convex constraint, the frequency safety constraint unit commitment model composed of various constraints and the objective function is a mixed integer nonlinear non-convex model and is difficult to solve directly. Therefore, a convex relaxation method is used to relax Equation (19) into a convex second-order cone constraint (30), making the model easier to solve and ensuring its accuracy.

[0108] The embodiments of the present invention are only examples and are not limiting.

[0109] Step 108: Transform the convex second-order cone constraint (30) to obtain the standard second-order cone constraint for the pipe storage relationship between time t and time t-1:

[0110]

[0111] Exemplarily, the convex second-order cone constraint formula (30) of the pipe storage relationship between time t and time t-1 is further transformed into the standard second-order cone constraint formula (30) of the pipe storage relationship between time t and time t-1, so as to make the model easier to solve, further improve the solution speed, and reduce the occupied computing space.

[0112] The embodiments of the present invention are only examples and are not limiting.

[0113] Step 109: Determine the optimal operating state of the unit combination based on the power system operation cost minimization objective function, frequency security constraints, power system operation constraints, natural gas system operation constraints, and power system and natural gas system coupling constraints.

[0114] The frequency security-constrained unit commitment model for coupled power and natural gas systems consists of multiple constraints and objective functions, including frequency security constraints, power system operation constraints, natural gas system operation constraints, and power and natural gas system coupling constraints. Each constraint and objective function pre-sets various system data and operating parameters. The frequency security-constrained unit commitment model for coupled power and natural gas systems is solved based on these system data and operating parameters to obtain operating parameters that minimize power system operating costs and determine the optimal operating state for the unit commitment. This approach minimizes power system operating costs while ensuring power system operational security and good system performance.

[0115] For example, existing commercial optimization software such as Gurobi and Cplex can be used to solve the frequency security-constrained unit commitment model of the coupled power and natural gas systems, thereby determining the optimal operating state of the unit commitment.

[0116] It should be noted that the embodiment of the present invention uses Gurobi and Cplex software to solve the frequency security constrained unit commitment model of the coupled power and natural gas systems. This is an exemplary description of the embodiment of the present invention. In other embodiments of the present invention, other software can also be used to solve the problem. The embodiment of the present invention is only an example and is not limiting.

[0117] It should be noted that for the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should be aware that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

[0118] In an embodiment of the present invention, an objective function for minimizing the operating cost of the power system corresponding to the frequency security-constrained unit combination is established; frequency security constraints are constructed; power system operating constraints are constructed; natural gas system operating constraints are constructed; and power system and natural gas system coupling constraints are constructed. The optimal operating state of the unit combination is determined based on the power system operating cost minimization objective function, frequency security constraints, natural gas system operating constraints, power system and natural gas system coupling constraints, and power system and natural gas system coupling constraints. This method considers the impact of natural gas system operating constraints and power system and natural gas system coupling constraints on power system frequency security-constrained units, optimizes the power system operating cost objective function under specified constraints, and minimizes the operating cost of the power system. This method can provide insights into operational analysis in the context of coupling power systems with other energy systems, and has both theoretical value and practical significance.

[0119] Example 2

[0120] Figure 2 This is a structural block diagram of a unit combination device with frequency safety constraints for coupling of electric power and natural gas systems provided in the second embodiment of the present invention, which may specifically include the following modules:

[0121] An objective function establishing module 201 is used to establish an objective function for minimizing the power system operation cost corresponding to the frequency security constrained unit commitment;

[0122] A frequency safety constraint building module 202 is used to build a frequency safety constraint;

[0123] In some embodiments of the present invention, the frequency safety constraint building module 202 includes:

[0124] Frequency change rate constraint construction submodule, used to construct frequency change rate constraint:

[0125] The frequency minimum point constraint construction submodule is used to construct the frequency minimum point constraint:

[0126] In some embodiments of the present invention, the frequency minimum point constraint construction submodule includes:

[0127] A mixed integer linear programming constraint conversion unit is used to perform mixed integer linear programming constraint conversion on the frequency minimum point constraint to obtain a new frequency minimum point constraint condition;

[0128] The quasi-steady-state frequency constraint construction submodule is used to construct the quasi-steady-state frequency constraint.

[0129] A power system operation constraint building module 203 is used to build power system operation constraints;

[0130] A natural gas system operation constraint building module 204 is used to build natural gas system operation constraints;

[0131] In some embodiments of the present invention, the natural gas system operation constraint building module 204 includes:

[0132] The convex relaxation transformation submodule is used to transform the pipe-storage relationship between time t and time t-1 to obtain a convex second-order cone constraint on the pipe-storage relationship between time t and time t-1;

[0133] The standard second-order cone constraint conversion submodule is used to convert the convex second-order cone constraint of the pipe-storage relationship between time t and time t-1 to obtain the standard second-order cone constraint of the pipe-storage relationship between time t and time t-1.

[0134] The power system and natural gas system coupling constraint construction module 205 is used to construct the power system and natural gas system coupling constraint;

[0135] The optimal operating state determination module 206 is used to determine the optimal operating state of the unit combination based on the power system operating cost minimization objective function, the frequency security constraint, the power system operation constraint, the natural gas system operation constraint, and the power system and natural gas system coupling constraint.

[0136] The unit combination device with frequency safety constraints for coupling of electric power and natural gas systems provided in an embodiment of the present invention can execute the unit combination method with frequency safety constraints for coupling of electric power and natural gas systems provided in any embodiment of the present invention, and has functional modules and beneficial effects corresponding to the execution method.

[0137] Example 3

[0138] Figure 3 A schematic diagram of the structure of a computer device provided in Example 3 of the present invention. Figure 3 A block diagram of an exemplary computer device 12 suitable for use in implementing embodiments of the present invention is shown. Figure 3 The computer device 12 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0139] like Figure 3As shown, computer device 12 is implemented as a general-purpose computing device. Components of computer device 12 may include, but are not limited to, one or more processors or processing units 16, system memory 28, and a bus 18 that connects various system components (including system memory 28 and processing unit 16).

[0140] Bus 18 represents one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or a local bus using any of a variety of bus architectures. Examples of these architectures include, but are not limited to, an Industry Standard Architecture (ISA) bus, a Micro Channel Architecture (MAC) bus, an Enhanced ISA bus, a Video Electronics Standards Association (VESA) local bus, and a Peripheral Component Interconnect (PCI) bus.

[0141] The computer device 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by the computer device 12, including volatile and non-volatile media, removable and non-removable media.

[0142] System memory 28 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. Computer device 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 34 may be configured to read and write non-removable, non-volatile magnetic media ( Figure 3 Not shown, often called a "hard drive"). Although Figure 3 Not shown, a magnetic disk drive for reading and writing to a removable non-volatile magnetic disk (e.g., a "floppy disk"), and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In these cases, each drive may be connected to bus 18 via one or more data media interfaces. Memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of various embodiments of the present invention.

[0143] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in memory 28. Such program modules 42 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may include an implementation of a network environment. Program modules 42 generally implement the functions and / or methods of the embodiments described herein.

[0144] The computer device 12 can also communicate with one or more external devices 14 (e.g., a keyboard, pointing device, display 24, etc.), one or more devices that enable a user to interact with the computer device 12, and / or any device that enables the computer device 12 to communicate with one or more other computing devices (e.g., a network card, a modem, etc.). Such communication can occur via an input / output (I / O) interface 22. Furthermore, the computer device 12 can communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network such as the Internet) via a network adapter 20. As shown, the network adapter 20 communicates with the other modules of the computer device 12 via a bus 18. It should be understood that, although not shown, other hardware and / or software modules can be used in conjunction with the computer device 12, including but not limited to microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0145] The processing unit 16 executes various functional applications and data processing by running programs stored in the system memory 28, such as implementing the unit commitment method for frequency security constraints of coupling of electric power and natural gas systems provided in an embodiment of the present invention.

[0146] Example 4

[0147] Embodiment 4 of the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the various processes of the above-mentioned unit combination method for coupling frequency safety constraints of the power and natural gas systems are implemented, and the same technical effects can be achieved. To avoid repetition, they will not be described here.

[0148] Among them, computer-readable storage media can include, for example, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or components, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device or device.

[0149] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A unit commitment method for coupling frequency safety constraints of power and natural gas systems, characterized in that: include: Establish the objective function of minimizing the power system operation cost corresponding to the unit commitment with frequency security constraints; Construct frequency safety constraints; Constructing power system operation constraints; Establishing natural gas system operation constraints; Construct coupling constraints between the power system and the natural gas system; determining the optimal operating state of the unit commitment according to the power system operation cost minimization objective function, the frequency security constraint, the power system operation constraint, the natural gas system operation constraint, and the power system and natural gas system coupling constraint; The construction frequency safety constraint includes: Construct a frequency rate of change constraint: Among them, H t is the inertia of the system at time t; and are the inertia constant and capacity of generator set i respectively; f0 is the rated frequency; is the power disturbance of the system at time t; RoCoF max is the maximum frequency change rate allowed; x i,t is the operating status of generator set i at time t; Build the frequency minimum point constraint: Among them, κ t It is the only solution of the following formula (4); Among them, T d is the transfer time; D is the load damping rate; is the total load level at time t; Δf DB is the dead time of the generator set speed governor; Δf max is the maximum frequency deviation allowed; R i,t is the reserve of generator set i at time t; Construct a quasi-steady-state frequency constraint: in, is the maximum allowable quasi-steady-state frequency deviation; G and N represent the collection of gas-fired units and non-gas-fired units.

2. The method according to claim 1, characterized in that In the power system operation cost minimization objective function corresponding to the unit commitment for establishing frequency security constraints, the power system operation cost minimization objective function is: Where T represents the set of time periods; G and N represent the sets of gas-fired units and non-gas-fired units; and is the starting and stopping cost of generator set i; is the no-load cost of generator set i; ci is the marginal power generation cost of generator set i; is the standby cost of generator set i; and are the start and stop states of generator set i at time t; x i,t is the operating status of generator set i at time t; P i,t and R i,t is the power output and reserve of generator set i at time t.

3. The method according to claim 2, characterized in that In the construction of power system operation constraints, the power system operation constraints are: Among them, formula (6) describes the logical relationship between the generator set state and the start-stop state; formula (7) uses binary variables to describe the generator set state, start state and shutdown state; Among them, formula (8) and formula (9) are the minimum operation time limit constraint and the minimum shutdown time limit constraint respectively, formula (10) is the generator output constraint, formula (11) is the standby output constraint, formula (12) is the generator set climbing constraint, formula (13) is the line transmission power constraint, and formula (14) is the system active power balance constraint; Where, and are the minimum operating time and minimum shutdown time of generator set i respectively; is the lower limit of the output of generator set i; is the spare capacity of generator set i; RD i and RU i are the downward and upward climbing limits of generator set i respectively; is the transmission capacity of transmission line l; ψ l,i is the transfer factor of generator set i to transmission line l; is the load d e Transfer factor for transmission line l; is the load d at time t e Level; D e A collection of loads.

4. The method according to claim 1, wherein In the construction of the natural gas system operation constraints, the natural gas system operation constraints are: Among them, formula (16) is used to calculate the average airflow in the pipeline; formula (17) is the pipeline airflow equation; formula (18) describes the relationship between the pipeline storage and the pressure of the two end nodes; formula (22) is used to calculate the air flow consumed by the compressor; Among them, formula (15) is the node airflow balance equation constraint; formula (19) is the pipe inventory relationship constraint between time t and time t-1; formula (20) is the total pipe inventory constraint at the end of the scheduling period is not less than the initial pipe inventory constraint; formula (21) is the air flow constraint through the compressor; formula (23) is the compressor boost ratio constraint; formula (24) is the air source output constraint; formula (25) is the node pressure constraint; Where, S(m), G(m), D g L(m) and C(m) are the gas source set, gas generator set, gas load set and compressor set connected to node m respectively; g is a collection of pipelines; is the output of gas source s at time t; is the gas flow consumed by the gas generator set g at time t; is the gas load d g The value at time t; is the air flow consumed by compressor k at time t; is the air flow through compressor k at time t; F mn,t is the gas flow rate of pipeline mn at time t; and are the inlet and outlet gas flows of pipeline mn at time t; C mn and K mn are all constant parameters of pipeline mn; π m,t and π n,t are the pressures on nodes m and n at time t; L mn,t is the pipe inventory of pipeline mn at time t; is the maximum capacity allowed to pass through compressor k; is the gas consumption ratio of compressor k; and The upper limit and lower limit of the compressor boost ratio respectively; and The maximum and minimum output limits of gas source s respectively; and are the upper and lower limits of the pressure on node m respectively.

5. The method according to claim 1, wherein In the construction of the coupling constraint between the power system and the natural gas system, the coupling constraint conditions between the power system and the natural gas system are: Where, is the energy conversion coefficient of the gas turbine unit; P g,t and R g,t are the output and reserve of gas generator set g at time t respectively.

6. The method according to claim 1, characterized in that Before determining the optimal operating state of the unit commitment according to the power system operation cost minimization objective function, the frequency security constraint, the natural gas system operation constraint, the power system and natural gas system coupling constraint, and the power system and natural gas system coupling constraint, the method further includes: By introducing auxiliary variables and transforming equation (3) into a mixed integer linear programming constraint, we can obtain the new frequency minimum point constraint: -Mx i,t ≤X i,t ≤Mx i,t (28) Among them, in formula (27) to formula (29), X i,t is an auxiliary variable introduced; M is a preset large positive number; Performing convex relaxation transformation on Equation (19) yields the convex second-order cone constraint of the pipe storage relation between time t and time t-1: The convex second-order cone constraint (30) is transformed to obtain the standard second-order cone constraint of the pipe storage relationship between time t and time t-1:

7. A unit combination device with frequency safety constraints for coupling of power and natural gas systems, characterized in that: include: An objective function establishment module is used to establish an objective function for minimizing the power system operation cost corresponding to the unit commitment with frequency security constraints; Frequency safety constraint building module, used to build frequency safety constraints; Power system operation constraint construction module, used to construct power system operation constraints; A natural gas system operation constraint building module, used to build natural gas system operation constraints; Power system and natural gas system coupling constraint construction module, used to construct power system and natural gas system coupling constraints; an optimal operating state determination module, configured to determine the optimal operating state of the unit combination according to the power system operating cost minimization objective function, the frequency security constraint, the power system operating constraint, the natural gas system operating constraint, and the power system and natural gas system coupling constraint; The construction frequency safety constraint includes: Construct a frequency rate of change constraint: Among them, H t is the inertia of the system at time t; and are the inertia constant and capacity of generator set i respectively; f0 is the rated frequency; is the power disturbance of the system at time t; RoCoF max is the maximum frequency change rate allowed; x i,t is the operating status of generator set i at time t; Build the frequency minimum point constraint: Among them, κ t It is the only solution of the following formula (4); Among them, T d is the transfer time; D is the load damping rate; is the total load level at time t; Δf DB is the dead time of the generator set speed governor; Δf max is the maximum frequency deviation allowed; R i,t is the reserve of generator set i at time t; Construct a quasi-steady-state frequency constraint: in, is the maximum allowable quasi-steady-state frequency deviation; G and N represent the collection of gas-fired units and non-gas-fired units.

8. A computer device, characterized in that: The computer device comprises: one or more processors; a memory for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the unit combination method for power and natural gas system coupling frequency security constraints according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the unit combination method for power and natural gas system coupling frequency security constraints is implemented as described in any one of claims 1-6.

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