Optimal load shedding method, device and system of integrated energy system, and storage medium

Abstract

The invention discloses an optimal load shedding method, device and system for an integrated energy system, and a storage medium. The method comprises the following steps: constructing an urban electrical coupling network model; according to the topological connection relation of the urban electrical network of the urban electrical coupling network model, the optimal load shedding scheme is found out by calculating the sensitivity of the nodes of the gas power plant, iteratively cutting off the fragile nodes and calculating the equal-consumption incremental rate after the nodes are cut off to serve as a circulation termination condition. By adopting the technical scheme of the invention, the optimal load shedding of the urban electrical integrated energy system is realized, and a decision maker can be helped to allocate emergency resources so as to realize more effective post-disaster recovery.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy management, and particularly relates to an optimal load shedding method, device, system, and storage medium for an integrated energy system. Background Art

[0002] With the transformation and optimization of the global energy structure, the integrated energy system (IES), as a new type of energy ecosystem, integrates multiple energy links such as electricity, natural gas, and heat / cold power, aiming to achieve efficient coordination and optimization of the energy supply chain. Through the interconnection of energy networks, the IES not only improves the energy conversion ability but also effectively compensates for the power fluctuations and uncertainties of renewable energy, which is of great significance for building an energy system with efficient and stable operation and the sustainable development of society. In order to improve the resilience of the electrical coupling network, it is necessary to conduct research on the cross-domain propagation model of IEGS to provide theoretical guidance for the safe and reliable operation of IEGS and the effective restoration of power supply and gas supply after extreme events.

[0003] At present, most research only considers the park-level electrical coupling system, and there is very little research on the urban-level electrical coupling network, ignoring the multi-level characteristics of the electrical integrated energy system. There is no optimal load shedding scheme for the urban-level electrical integrated energy system, and it cannot provide theoretical guidance for large-scale electrical integrated energy systems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an optimal load shedding method, device, system, and storage medium for an integrated energy system, which iteratively searches based on the fault conduction model and evaluation index of the electrical coupling network to achieve the optimal load shedding of the urban-level electrical integrated energy system, and can help decision-makers allocate emergency resources to achieve more effective post-disaster recovery.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An optimal load shedding method for an integrated energy system, comprising:

[0007] Constructing a model of the urban electrical coupling network;

[0008] According to the topological connection relationship of the urban electrical network in the urban electrical coupling network model, by calculating the sensitivity of the gas power plant nodes, iteratively removing the vulnerable nodes, and calculating the equal incremental rate of fuel consumption after removing the nodes as the loop termination condition, finding the optimal load shedding scheme.

[0009] The present invention also provides an optimal load shedding method for an integrated energy system, comprising:

[0010] Step 1: Obtaining the network topological structure, line power flow, node injection power, and sensitivity data of the target area power grid and gas network;

[0011] Step 2: Calculate the initial operating point, the initial gas pressure of the gas power plant, and the operating states of the change nodes.

[0012] Step 3: Calculate the operating state of the high-voltage power transmission and distribution network.

[0013] Step 4: Calculate the state of the electricity-gas coupling components.

[0014] Step 5: Calculate the operating states of the nodes in the gas network.

[0015] Step 6: Calculate the incremental fuel cost rate for the loop termination condition. Check if it is less than zero. If it is less than zero, proceed to Step 8; if it is greater than zero, proceed to Step 7.

[0016] Step 7: Output the node with the highest sensitivity among the remaining nodes in the gas network and return to Step 2.

[0017] Step 8: Import the urban power grid data and calculate the states of the low-voltage distribution network and the gas distribution network.

[0018] Step 9: Calculate the number of affected users in the electricity-gas coupling network.

[0019] The present invention also provides an optimal load shedding device for an integrated energy system, including:

[0020] A first processing module for constructing an urban electricity-gas coupling network model.

[0021] A second processing module for, according to the topological connection relationship of the urban electricity network in the urban electricity-gas coupling network model, calculating the sensitivity of the gas power plant nodes, iteratively removing vulnerable nodes, calculating the incremental fuel cost rate after removing the nodes as the loop termination condition, and finding the optimal load shedding scheme.

[0022] The present invention also provides an optimal load shedding system for an integrated energy system, including: a memory and a processor. A computer program is stored on the memory and run by the processor. When the computer program is run by the processor, it executes the optimal load shedding method for the integrated energy system.

[0023] An embodiment of the present invention also provides a storage medium on which a computer program is stored. When the computer program runs, it executes the optimal load shedding method for the integrated energy system.

[0024] Based on the topological connection relationship of the urban electricity-gas coupling network model, the present invention calculates the sensitivity of the gas power plant nodes, iteratively removes vulnerable nodes, calculates the incremental fuel cost rate after removing the nodes as the loop termination condition, finds the optimal load shedding scheme, and improves the stability of the gas power plant nodes; it provides a reference for the post-disaster emergency response of the urban electricity-gas integrated energy system. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0026] Figure 1 It is a flowchart of the optimal load shedding method for the integrated energy system in the embodiment of the present invention; Detailed Embodiments

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0029] Embodiment 1:

[0030] The embodiment of the present invention provides an optimal load shedding method for an integrated energy system, including:

[0031] Construct a model of the urban electrical coupling network;

[0032] According to the topological connection relationship of the urban electrical network in the urban electrical coupling network model, by calculating the sensitivity of the gas power plant nodes, iteratively removing the vulnerable nodes, and calculating the equal incremental rate of fuel consumption after removing the nodes as the loop termination condition, find the optimal load shedding scheme.

[0033] Based on the topological connection relationship of the urban electrical coupling network model, by calculating the sensitivity of the gas power plant nodes and iteratively removing the vulnerable nodes, the present invention finds the optimal load shedding scheme to improve the stability of the gas power plant nodes, providing a reference for the post-disaster emergency disposal of the urban electrical integrated energy system.

[0034] Embodiment 2:

[0035] A model is adopted to characterize the impact of N-k faults on load loss and pump operation (function fF2P). Generally, the UPN part is served by internal thermal power plants and gas power plants, and partly by the external transmission system. The load loss is determined by four factors, including the economic dispatch of thermal power plants, the stable operation of gas power plants, network reconfiguration, and optimal load shedding. The modeling of UPN consists of a meshed HVT network, substations, and an HVD network. Based on the input parameters of line fault status and the operation of gas power plants, the simplified economic dispatch model is given by equations (1.1)-(1.10).

[0036]

[0037] θ ref = 0 (5)

[0038]

[0039] z g = 0, ij ∈ Ω EBF (9)

[0040]

[0041] The objective function (1) minimizes the total cost of generators and load shedding. Constraint (2) enforces the output limits of the generator sets. The load shedding limit is given by (3-4). The DC power flow equation is used to model the power flow in the N-k fault scenario, as shown in (5)-(8). Equation (5) specifies the voltage angle of the reference bus. Constraint (6) represents the bus power balance. Note: Only a small number of nodes are equipped with generator sets; if there is no generator, then PG j,t is set to 0. (7) represents the branch power flow, which is relaxed if the branch is open. Equation (8) limits the upper limit of the branch power flow. If the branch (i,j) fails, then Pij,t = 0. (9) limits the state of the fault branch. Equation (10) indicates that the HVD network maintains a radial structure by opening switches in loop k. The optimal load shedding is converted to the number of affected customers, given by (11).

[0042]

[0043] If the substation is not powered by the upstream system (including gas power plants), the substation will lose power. In addition, if the substation loses power or the local power supply is lower than the WTP load, the substation is identified as unable to support the WTP, as shown in (12).

[0044]

[0045] To clearly show the relationship between the output of a gas generator and the natural gas injection volume, based on the accurate model of the gas generator, it is assumed that the influence of ambient changes on the operation of the gas generator is negligible, and the internal cycle of the gas generator is considered to be completely ideal. Thus, a multi-state output reliability model of the gas generator is established. The overall energy conversion process of the gas generator can be described by formulas (1.13)-(1.16):

[0046] -W×C pa (T 2 -T 1 )+W×C pc (T 3 -T 4 )=P (13)

[0047]

[0048] Where W is the total flow rate of natural gas W f and air W a , W = W f +W a ; C pa 、C pc are the heat capacities of air and natural gas respectively; T i is the temperature at different points inside the gas generator, and the subscripts 1, 2, 3, 4 are the temperatures at the inlet and outlet of the air compressor, the inlet of the combustion chamber, and the outlet respectively, H u is the lower calorific value of natural gas; P is the power generation of the gas generator, where p i is the pressure at different points inside the gas generator; ηc ,η t are the efficiencies of the air compressor and the turbine respectively; σ is a constant, and in the embodiments of the present invention, it is taken as 1.4. Since it is assumed that the internal cycle of the gas generator is completely ideal, the pressure of each part of the gas generator remains unchanged, and (1.17) and (1.18) can be written as:

[0049]

[0050] T 3 -T 4 =T 3 ×η t ×K 2 (18)

[0051] Combining formulas (1.13)-(1.16), the relationship between the output of the gas generator and the injected natural gas flow rate can be obtained:

[0052]

[0053] The function fP2H is based on the comprehensive hydraulic modeling of the GDN. The pipe network has the dual functions of natural gas transmission and storage, and can buffer and regulate the hazards caused by the uncertainty of gas load demand or the output of new energy grid connection to the operation of the natural gas system. In addition, as the core equipment of pipeline transportation, compressors can effectively improve the energy supply reliability of the natural gas system. During the long-distance gas transmission process, the pipe network will have pressure loss due to pipeline friction, so the gas in the pipeline may face the problem of slow or even stagnant flow. For the actual use scenarios of compressors in natural gas networks, they are limited to gas drainage and production, gas gathering and treatment, pipeline transportation, and gas storage. In urban natural gas pipe networks, the use scenarios of compressors are limited to natural gas compressor stations, vehicle gas filling stations, and gas storage. A large number of pressure regulating stations and pressure regulators are used in urban natural gas pipe networks, making the urban gas network and the urban power grid also have multi-level networks. Since gas has different physical properties at different pressure levels, a multi-level gas network calculation model is established to better simulate gas network faults.

[0054] Basic formula for hydraulic calculation of low-pressure gas pipelines:

[0055]

[0056] If the customary common units are adopted and considering that the pressure of urban gas pipelines is generally below 1.6 MPa and Z0 = 1, the basic calculation formulas for high- and medium-pressure gas pipelines are:

[0057]

[0058] p 1 is the starting pressure of the pipeline (Pa), p 2 is the ending pressure of the pipeline (Pa), L is the calculated length of the pipeline (m), Q 0 is the calculated flow rate of the gas pipeline (Nm 3 / h), d is the inner diameter of the pipeline (mm), ρ 0 is the gas density (kg / Nm 3) , λ is the friction resistance coefficient of the gas pipeline, T is the standard temperature of the gas (K), T 0 is the absolute temperature at standard state (273.15 K).

[0059] Basic calculation formula for low-pressure pipelines

[0060]

[0061] Due to the multi-pressure-level characteristics of the natural gas system, each pressure level is connected by pressure regulators and pressure regulating stations. The urban gas network has a radial network and a loop network. Different pressures of gas have different physical states, and different pressure levels require different calculation models. Through multi-level constraints

[0062] The high-pressure gas network includes node flow balance constraints, pipeline flow upper and lower limit constraints, gas load reduction constraints, and component operation constraints, etc. Its model can be expressed as:

[0063]

[0064] f mr = V lcak + f rn (25)

[0065] π i,min ≤ π i ≤ π i, max (26)

[0066] f ij,min ≤ f ij ≤ f ij, max (27)

[0067] W s,min ≤ W s ≤ W s, max (28)

[0068] 0 ≤ ΔW g ≤ W g (29)

[0069] Where: Ψ GS 、Ψ GT 、Ψ GC 、Ψ j are the sets of gas sources, gas turbines, compressors, and natural gas pipelines respectively; W s 、f c are the gas output of the gas source and the gas flow rate in the branch where the compressor is located respectively.

[0070] Constraints of medium-pressure and low-pressure gas networks

[0071]

[0072] f mr = V lcak + f rn (31)

[0073] π i,min ≤ π i ≤ π i, max (32)

[0074] f ij,min ≤ f ij ≤ f ij, max (33)

[0075] Y s,min ≤ Y s ≤ Y s, max (34)

[0076] 0 ≤ ΔW g ≤ W g (35) where: Ψ TS and Ψ j are the pressure regulator and the natural gas pipeline network respectively; Y s are the gas output of the pressure regulator respectively.

[0077] Due to the multi-pressure level characteristics of the urban natural gas system, different pressure level networks are connected by pressure regulators and pressure regulating stations. For the optimal load shedding scheme of the power grid, a very mature system already exists. However, the optimal load shedding scheme for the urban gas network has not been proposed yet. Natural gas has slow dynamic characteristics. During the transmission process of natural gas, part of the gas is stored in the pipeline in the form of pipeline inventory, making the change of pipeline flow a slow process. By utilizing the slow dynamic characteristics of natural gas, through the optimal load shedding scheme of the urban gas network, the gas pressure at the gas turbine node can be controlled to be stable. The embodiments of the present invention combine the electrical coupling vulnerability identification method to propose an optimal load shedding scheme for the urban gas network considering the operating state of the gas turbine. Since the urban gas network has a radial network and a loop network, and the physical states of the gas at different pressure levels are different, the calculation methods are also different. Through the analysis of the natural gas network topology diagram, the number of nodes in the low-pressure gas network is large and the distance from the gas turbine node is far, having little impact on the gas turbine node. To simplify the operation, the load shedding range is controlled in the medium-pressure and high-pressure gas networks.

[0078] The embodiments of the present invention define Q i the sensitivity matrix R of the natural gas node pressure - gas turbine node pressure growth L , the influence of different nodes on the gas turbine node. The gas turbine is an important coupling element of the IEGS. The operating state of the gas turbine is characterized as the operating state of the IEGS system, and thus the weak pressure link of the IEGS is located.

[0079] Definition:

[0080]

[0081] This index reflects the sensitivity of the gas pressure at the gas turbine node m of the natural gas system to the gas load growth at node L. The larger this index, the greater the influence of the changing node on the gas turbine node, and thus the weak pressure link of the system can be further identified. Through the important coupling nodes of electrical coupling, the weak pressure link of the IEGS of the gas network nodes is found.

[0082] First, calculate the sensitivity matrix R of the natural gas node pressure - gas turbine node pressure growth Lp , and then perform iterative operations to calculate the equal incremental consumption rate by sensitivity from high to low and iterative excision:

[0083]

[0084] Where S is the multi-output power of the gas turbine, and ΔL is the change value of the output flow before and after the low-pressure gas network regulator cuts the load

[0085] When D = 0, stop the iteration, output the excision node, and calculate the final impact on users.

[0086] Such as Figure 1 As shown, an optimal load shedding method for an integrated energy system according to an embodiment of the present invention includes:

[0087] Step 1: Obtain the network topology structure, line power flow, node injection power, and sensitivity data of the target area power grid and gas network; among them, the sensitivity data is calculated through formula (36);

[0088] Step 2: Calculate the initial operating point, the initial gas pressure of the gas power plant, and the operating state of the changing nodes through formulas (20)-(35);

[0089] Step 3: Calculate the operating state of the high-voltage transmission and distribution power grid through the power grid calculation formulas (1)-(13);

[0090] Step 4: Calculate the state of the electricity-gas coupling element by coupling element calculation formulas (13)-(29);

[0091] Step 5: Calculate the operating state of each node of the gas network through formulas (20)-(35);

[0092]

[0093] If it is less than zero, go to step 8; if it is greater than zero, go to step 7;

[0094] Step 7: Output the node with the highest sensitivity among the remaining nodes of the gas network, and return to step 2;

[0095] Step 8: Import the urban power grid data to calculate the state of the low-voltage distribution power grid and the gas distribution network;

[0096] Step 9: Calculate the number of users affected by the electricity-gas coupling network.

[0097] Embodiment 3:

[0098] An embodiment of the present invention further provides an optimal load shedding device for an integrated energy system, including:

[0099] The first processing module is used to construct an urban electrical coupling network model;

[0100] A second processing module, configured to, according to the topological connection relationship of the urban electrical network in the urban electrical coupling network model, iteratively remove vulnerable nodes by calculating the sensitivity of the gas power plant nodes, calculate the incremental fuel cost after removing the nodes as the loop termination condition, and find the optimal load shedding scheme.

[0101] Embodiment 4:

[0102] An embodiment of the present invention further provides an optimal load shedding system for an integrated energy system, including: a memory and a processor, where a computer program run by the processor is stored on the memory, and the computer program, when run by the processor, executes the optimal load shedding method for the integrated energy system.

[0103] Embodiment 5:

[0104] An embodiment of the present invention further provides a storage medium, where a computer program is stored on the storage medium, and the computer program, when running, executes the optimal load shedding method for the integrated energy system.

[0105] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An optimal load shedding method for an integrated energy system, characterized in that: include: Construct urban electrical coupling network model; According to the topological connection relationship of the urban electrical network of the urban electrical coupling network model, the sensitivity of the gas power plant nodes is calculated, the vulnerable nodes are iteratively removed, and the equal consumption slight increase rate after the node removal is calculated as the cycle termination condition to find the optimal load shedding plan.

2. An optimal load shedding method for an integrated energy system, characterized in that: include: Step 1: Obtain the network topology, line flow, node injection power, and sensitivity data of the target area power grid and gas grid; Step 2: Calculate the initial operating point, the initial gas pressure of the gas power plant and the operating status of the change node; Step 3: Calculate the operating status of the high voltage transmission and distribution network; Step 4, calculating the state of the electric-pneumatic coupling element; Step 5: Calculate the operating status of each node in the gas network; Step 6: Calculation of the slight increase rate of consumption under cycle termination conditions Is it less than zero? If so, proceed to step eight; if greater than zero, proceed to step seven; Step 7: Output the node with the highest sensitivity among the remaining nodes in the gas network, and return to step 2; Step 8: Import the city power grid data to calculate the status of the low-voltage distribution network and the gas distribution network; Step 9: Calculate the number of users affected by the electric-gas coupling network.

3. An optimal load shedding device for a comprehensive energy system, characterized in that: include: The first processing module is used to construct a city electrical coupling network model; The second processing module is used to find the optimal load shedding plan based on the topological connection relationship of the urban electrical network of the urban electrical coupling network model, by calculating the sensitivity of the gas power plant nodes, iteratively removing the vulnerable nodes, and calculating the equal consumption slight increase rate after the node removal as the cycle termination condition.

4. An optimal load shedding system for an integrated energy system, characterized in that: include: A memory and a processor, wherein the memory stores a computer program executed by the processor, and when the computer program is executed by the processor, the optimal load shedding method for the integrated energy system as claimed in claim 2 is executed.

5. A storage medium, characterized in that: The storage medium stores a computer program, which, when running, executes the optimal load shedding method for the integrated energy system as described in claim 2.

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