Two-stage resilience recovery method for electrical coupling system considering component importance recognition

Abstract

The application discloses a kind of electric-gas coupling system stage toughness recovery method considering element importance recognition.Method includes: obtaining the importance index of each element according to the system function level of each element removed electric-gas coupling system;In the case where reinforcement constraint is considered, each important element is reinforced in pre-event stage;In post-event stage, the load data to be recovered of electric-gas coupling system is input into electric-gas coupling system toughness recovery optimization model, and the recovery decision variable of the element set to be recovered is output, toughness recovery is carried out according to recovery decision variable, and finally realizes the element reinforcement and toughness recovery of electric-gas coupling system two stages.The method of the application can guide the system energy supply recovery of electric-gas coupling system in pre-event stage and post-event stage to be realized quickly and effectively, and the electric power load and natural gas load after extreme event occur are recovered quickly, so as to effectively improve the overall toughness level of electric-gas coupling system.

Description

TECHNICAL FIELD

[0001] The application relates to a two-stage resilience recovery method for an electric-gas coupling system, in particular to a two-stage resilience recovery method for an electric-gas coupling system considering element importance identification. BACKGROUND

[0002] In recent years, with the continuous increase of natural gas power generation capacity and the gradual maturity of electric-gas conversion technology, the coupling degree of the electric power system and the natural gas system is increasing. The close coupling of the two systems not only brings economic benefits, but also may increase the risk of large-scale fault propagation, and even lead to the collapse of the entire electric-gas coupling system. Therefore, for the case of large-scale energy supply interruption of the electric-gas coupling system, a fast and effective recovery strategy is of great significance to reduce economic losses and improve the resilience capability of the system.

[0003] Existing researches are all aimed at the independent operation scene of the electric power system, ignoring the influence of the coupling characteristics between the natural gas system and the electric power system on the recovery strategy. On the one hand, the resilience research of the electric-gas coupling system needs to consider not only the recovery process of the electric power system, but also the recovery process of the natural gas system, and how to establish a unified resilience recovery framework based on the different physical characteristics of the two systems is a key and difficult point. On the other hand, the recovery processes of the electric power system and the natural gas system need to be coordinated, and the recovery decision of the coupling equipment depends not only on the system it belongs to, but also on the coupling system, which will be more complex than the recovery decision of a single energy system. SUMMARY

[0004] In order to solve the problems in the background art, the application provides a two-stage resilience recovery method for an electric-gas coupling system considering element importance identification.

[0005] The technical scheme adopted by the application is:

[0006] The two-stage resilience recovery method for an electric-gas coupling system provided by the application comprises the following steps:

[0007] 1) An electric-gas coupling system comprising a plurality of elements is established, the system function level of the electric-gas coupling system after removal of each element in the electric-gas coupling system is obtained, and the importance index of each element in the electric-gas coupling system is obtained according to the system function level of the electric-gas coupling system after removal of each element.

[0008] 2) According to the importance index of each element in the electric-gas coupling system, a plurality of elements among the elements are selected as important elements under the condition of considering reinforcement constraints, and the important elements are reinforced in the pre-event stage before the electric-gas coupling system encounters an extreme event.

[0009] 3) in the case of considering the electrical coupling recovery optimization constraint, establish the resilience recovery optimization model of the electrical-gas coupling system; form a to-be-recovered element set by excluding some elements from each important element in each element in the electrical-gas coupling system, obtain the to-be-recovered load data of the electrical-gas coupling system in the post-event stage after the electrical-gas coupling system encounters an extreme event, input the to-be-recovered load data of the electrical-gas coupling system into the resilience recovery optimization model of the electrical-gas coupling system, and the resilience recovery optimization model of the electrical-gas coupling system outputs the recovery decision variable of the to-be-recovered element set; according to the recovery decision variable, some elements in the to-be-recovered element set are removed, so that the electrical coupling system realizes resilience recovery, and finally realizes the element reinforcement and resilience recovery of the electrical-gas coupling system in two stages.

[0010] In the step 1), the electrical-gas coupling system includes a power network and a natural gas network, the power network includes a plurality of electric nodes, generator sets, transformer substations and electric load devices, each electric node is connected through each power transmission line, each generator set, transformer substation and electric load device is located at a respective electric node, each generator set includes a gas turbine unit and a non-gas turbine unit, and the non-gas turbine unit is specifically a coal-fired turbine unit, a nuclear power turbine unit or a hydroelectric turbine unit; each electric load device includes an electric load device consuming a conventional electric load and an electric load device consuming a converted gas load, and the conventional electric load is used for normal work of an electric load device irrelevant to the natural gas network.

[0011] The natural gas network includes a plurality of gas nodes, gas source devices, compressor devices and gas load devices, each gas node is connected through each gas transmission pipeline, each gas source device and gas load device is located at a respective gas node, each gas source device includes a conventional gas source and an electric-gas conversion device, and each gas load device includes a gas load device consuming a conventional gas load and a gas load device consuming a converted electric load, and the conventional gas load is used for normal work of a gas load device irrelevant to the power network; the natural gas network further includes a plurality of compressor branches, each end of each compressor branch is connected to a gas node, and each compressor branch is provided with a compressor device.

[0012] Each electric node where each gas turbine unit in the power network is located is connected to each gas node where each gas load device consuming a converted electric load in the natural gas network is located; each gas node where each electric-gas conversion device in the natural gas network is located is connected to each electric node where each electric load device consuming a converted gas load in the power network is located.

[0013] Each element in the electrical-gas coupling system includes each power transmission line in the power network and each gas transmission pipeline and compressor branch in the natural gas network.

[0014] The power-gas interdependence links in the electricity-gas coupling system include gas turbine unit dependent link and electric-gas conversion device dependent link. The gas turbine unit dependent link refers to the link between the electric node where the gas turbine unit is located in the power network and the gas node where the gas turbine unit is located in the natural gas network. The electric-gas conversion device dependent link refers to the link between the electric node where the electric-gas conversion device is located in the power network and the gas node where the electric-gas conversion device is located in the natural gas network. The natural gas fuel consumed by the gas turbine unit for power generation depends on the gas node of the natural gas network; the power load required by the electric-gas conversion device for normal operation depends on the electric node of the power network.

[0015] In the step 1), the system function level of the electricity-gas coupling system after removing each element in the electricity-gas coupling system is obtained, and the importance index of each element in the electricity-gas coupling system is obtained according to the system function level of the electricity-gas coupling system after removing each element, which is specifically as follows:

[0016]

[0017] wherein, LOR(ξ) represents the importance index of the element ξ in the electricity-gas coupling system; t1 and t e respectively represent the starting time and the ending time of the resilience process of the element ξ in the electricity-gas coupling system; represents the expected system function level of the electricity-gas coupling system at the time t, and the system function level is the load level that the electricity-gas coupling system has recovered at the time t; represents the system function level of the electricity-gas coupling system at the time t; represents the system function level of the electricity-gas coupling system after removing the element ξ in the electricity-gas coupling system at the time t.

[0018] In the step 2), the reinforcement constraint is specifically as follows:

[0019]

[0020] wherein, Γ represents the total number of reinforced elements in the electricity-gas coupling system, χ ξ represents the reinforcement decision variable of the element ξ in the electricity-gas coupling system, if the element ξ is reinforced, the reinforcement decision variable χ ξ = 1, otherwise χ ξ = 0; H is the preset number of reinforced elements.

[0021] According to the importance indexes of the elements in the electro-gas coupling system, in the case of considering reinforcement constraints, a plurality of elements in the elements are selected as important elements, the important elements are reinforced in the pre-event stage before the electro-gas coupling system encounters an extreme event, specifically, the importance indexes of the elements in the electro-gas coupling system are sorted in descending order according to the numerical values, in the case of considering reinforcement constraints, the total number of reinforced elements Γ in the electro-gas coupling system is determined, and the elements corresponding to the top Γ importance indexes are selected as important elements for reinforcement; when the total number of elements in the electro-gas coupling system is greater than or equal to a preset reinforcement element number H, the total number of reinforced elements Γ in the electro-gas coupling system is equal to the preset reinforcement element number H.

[0022] All the reinforced elements will not be severely damaged after the extreme event and can be restored to the normal operating state, thereby minimizing the loss of resilience caused by element removal.

[0023] In step 3), in the case of considering the electro-gas coupling recovery optimization constraints, the resilience recovery optimization model of the electro-gas coupling system is established, specifically as follows:

[0024]

[0025]

[0026]

[0027]

[0028] wherein R represents the system resilience index of the electro-gas coupling system, T represents the duration of the post-event stage, the duration T of the post-event stage is divided into a plurality of time periods, N T represents the total number of time periods into which the duration T of the post-event stage is divided; and respectively represent the power network function level and the natural gas network function level at time t, and υ represents a weight coefficient; V e and V g respectively represent the set of electric nodes of the power network and the set of gas nodes of the natural gas network; and respectively represent the working state variable of the electric node i of the power network and the gas node j of the natural gas network at time t, if the working state of the electric node i of the power network or the gas node j of the natural gas network at time t has been restored, the working state variable of the electric node i of the power network or the gas node j of the natural gas network at time t is equal to 1, otherwise, it is equal to 0; τ or e,i and ​respectively represent the cut load cost coefficient and the to-be-restored load size on the electric node i of the power network; τ g,j and respectively represent the cut load cost coefficient and the to-be-restored load size on the gas node j of the natural gas network, and the product of the two represents the load value on the node; the cost is specifically a relevant quantity of consumed electric quantity or natural gas quantity.

[0029] The electrical coupling restoration optimization constraint is specifically as follows:

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] wherein, and respectively represent the restoration decision variable of the power transmission line l in the power network, the gas transmission pipeline p in the natural gas network and the compressor branch c at the t period, if the working state of the power transmission line l in the power network, the gas transmission pipeline p in the natural gas network or the compressor branch c at the t period has been restored, the restoration decision variable of the power transmission line l in the power network, the gas transmission pipeline p in the natural gas network or the compressor branch c at the t period is equal to 1, otherwise equal to 0, when the restoration decision variable of the power transmission line l in the power network, the gas transmission pipeline p in the natural gas network or the compressor branch c at the t period is equal to 0, the power transmission line l in the power network, the gas transmission pipeline p in the natural gas network or the compressor branch c is removed in the electrical-gas coupling system;E r represent the removed element set, the removed element set is contained in the to-be-restored element set; and respectively represent the working state variables of the transmission line l in the power network, the gas pipeline p in the natural gas network and the compressor branch c at time t, if the working state of the transmission line l in the power network, the gas pipeline p in the natural gas network or the compressor branch c has been restored at time t, the working state variable of the transmission line l in the power network, the gas pipeline p in the natural gas network or the compressor branch c at time t is equal to 1, otherwise it is equal to 0; and respectively represent the restoration decision variables of the transmission line l in the power network, the gas pipeline p in the natural gas network and the compressor branch c in m time periods, if the working state of the transmission line l in the power network, the gas pipeline p in the natural gas network or the compressor branch c has been restored in m time periods, the restoration decision variable of the transmission line l in the power network, the gas pipeline p in the natural gas network or the compressor branch c in m time periods is equal to 1, otherwise it is equal to 0, when the restoration decision variable of the transmission line l in the power network, the gas pipeline p in the natural gas network or the compressor branch c in m time periods is equal to 0, the transmission line l in the power network, the gas pipeline p in the natural gas network or the compressor branch c is removed in the electric-gas coupling system;E line 、E pipe andE com respectively represent the set of all power lines in the power network, the set of all gas pipelines in the natural gas network and the set of compressor branches;η gfu,i represents the energy conversion coefficient of the gas turbine unit on the electric node i of the power network; represents the gas-to-electricity load output of the gas load device consuming the gas-to-electricity load on the gas node j of the natural gas network in t time period; ρ represents the heat value of the natural gas; represents the power generation of the gas turbine unit on the electric node i of the power network in t time period, and respectively represent the upper limit and the lower limit of the power generation of the gas turbine unit on the electric node i of the power network in t time period; represents the working state variable of the gas turbine unit on the electric node i of the power network at time t, if the resilience of the gas turbine unit on the electric node i of the power network has been restored at time t, the working state variable of the gas turbine unit on the electric node i of the power network at time t is equal to 1, otherwise it is equal to 0; represents the upper limit of the gas-to-electricity load of the gas load device consuming the gas-to-electricity load on the gas node j of the natural gas network.

[0040] In step 3), the to-be-restored load data of the electric-gas coupling system is obtained in the post-event stage after the electric-gas coupling system encounters an extreme event, and the to-be-restored load data of the electric-gas coupling system includes the to-be-restored load size of the electric node i of the power network ​and the size of the load to be restored on the gas node j of the natural gas network inputting the data of the load to be restored of the electric-gas coupling system into an electric-gas coupling system resilience recovery optimization model, the electric-gas coupling system resilience recovery optimization model outputting recovery decision variables of the set of elements to be restored, the recovery decision variables of the set of elements to be restored including recovery decision variables of the power transmission line l in the power network, the gas transmission pipeline p and the compressor branch c in the natural gas network in the t period and determining a removal strategy of the elements in the set of elements to be restored according to the recovery decision variables, that is, determining to remove several elements in the set of elements to be restored, so that the electric-gas coupling system achieves resilience recovery, and the elements with high recovery importance are recovered first to speed up the resilience recovery of the electric-gas coupling system, and finally achieve the two-stage reinforcement and resilience recovery of the electric-gas coupling system, that is, the element reinforcement in the pre-event stage and the element resilience recovery in the post-event stage.

[0041] extreme event simulation of the electric-gas coupling system resilience, and evaluating the resilience ability of the electric-gas coupling system under the method of the application to resist extreme events through the expected loss resilience index, specifically as follows:

[0042]

[0043] wherein, ELOR represents the expected loss resilience index; n s represents the total simulation times; represents the removed element set under the σth extreme event simulation; is the resilience loss value of the set of elements to be restored under the σth extreme event simulation .

[0044] The beneficial effects of the application are:

[0045] In the case of disasters caused by extreme events, the electric-gas coupling system with closely coupled power network and natural gas network causes large-scale energy supply interruption, the application can obtain the element reinforcement result in the pre-event stage and the element resilience recovery result in the post-event stage of the electric-gas coupling system, thereby guiding the reinforcement and recovery of the power line and the natural gas pipeline, and quickly and effectively achieving the system energy supply recovery of the electric-gas coupling system in the pre-event stage and the post-event stage, quickly recovering the power load and the natural gas load after the extreme event, thereby effectively improving the overall resilience level of the electric-gas coupling system, and having important significance for providing system resilience capability. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is an embodiment structure schematic diagram of the electric-gas coupling system of the application;

[0047] Figure 2 is a flowchart of the method of the application. DETAILED DESCRIPTION

[0048] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] As shown in the figure, the two-stage resilience recovery method of the electrical-coupled system of the application comprises the following steps: Figure 2

[0050] 1) Establishing an electrical-coupled system comprising a plurality of elements, obtaining the system function level of the electrical-coupled system after removal of each element in the electrical-coupled system, and obtaining the importance index of each element in the electrical-coupled system according to the system function level of the electrical-coupled system after removal of each element.

[0051] In step 1), the electrical-coupled system comprises a power network and a natural gas network, the power network comprises a plurality of electric nodes, generator sets, transformer substations and electric load devices, each electric node is connected with each other through each power transmission line, each generator set, transformer substation and electric load device is located at a respective electric node, each generator set comprises a gas-fired generator set and a non-gas-fired generator set, and the non-gas-fired generator set is specifically a coal-fired generator set, a nuclear power generator set or a hydroelectric generator set, etc.; each electric load device comprises an electric load device consuming a conventional electric load and an electric load device consuming a converted gas load, and the conventional electric load is used for normal work of an electric load device irrelevant to the natural gas network.

[0052] The natural gas network comprises a plurality of gas nodes, gas source devices, compressor devices and gas load devices, each gas node is connected with each other through each gas transmission pipeline, each gas source device and gas load device is located at a respective gas node, each gas source device comprises a conventional gas source and an electric-gas converted device, and each gas load device comprises a gas load device consuming a conventional gas load and a gas load device consuming a converted electric load, and the conventional gas load is used for normal work of a gas load device irrelevant to the power network; the natural gas network further comprises a plurality of compressor branches, both ends of each compressor branch are connected with a gas node, and each compressor branch is provided with a compressor device.

[0053] Each electric node where each gas-fired generator set in the power network is located is connected with each gas node where each gas load device consuming a converted electric load in the natural gas network is located; each gas node where each electric-gas converted device in the natural gas network is located is connected with each electric node where each electric load device consuming a converted gas load in the power network is located.

[0054] Each element in the electrical-coupled system comprises each power transmission line in the power network and each gas transmission pipeline and compressor branch in the natural gas network.

[0055] ​In an electro-gas coupling system, the interdependencies between electricity and natural gas include the gas turbine dependency link and the power-to-gas (EPG) equipment dependency link. The gas turbine dependency link refers to the connection between the electrical node of the gas turbine in the power grid and the gas node in the natural gas network. The EPG equipment dependency link refers to the connection between the electrical node of the EPG equipment in the power grid and the gas node in the natural gas network. The natural gas fuel consumed by the gas turbine for power generation depends on the gas node in the natural gas network; the electrical load required for the EPG equipment to maintain normal operation depends on the electrical node in the power grid.

[0056] In step 1), the system functional level of the electro-electric coupling system after removing each component is obtained. Based on the system functional level of the electro-electric coupling system after removing each component, the importance index of each component in the electro-electric coupling system is obtained, as follows:

[0057]

[0058] Where LOR(ξ) represents the importance index of component ξ in the electro-electric coupling system; t1 and t e These represent the start and end times of the ductile recovery process of component ξ in the electro-pneumatic coupling system, respectively. This represents the expected system function level of the electro-pneumatic coupling system at time t. The system function level is the load level that the electro-pneumatic coupling system has recovered at time t. This indicates the system functional level of the electro-pneumatic coupling system at time t. The system function level of the electro-pneumatic coupling system after the component ξ is removed at time t is indicated.

[0059] 2) Based on the importance index of each component in the electro-pneumatic coupling system, and considering the hardening constraints, select several components as important components and harden each important component in the pre-event stage before the electro-pneumatic coupling system encounters an extreme event.

[0060] In step 2), the reinforcement constraints are as follows:

[0061]

[0062] Where Γ represents the total number of hardened components in the electro-pneumatic coupling system, and χ ξ Let χ represent the hardening decision variable for component ξ in an electro-pneumatic coupling system. If component ξ is hardened, then the hardening decision variable χ... ξ =1, otherwise χ ξ =0; H is the preset number of reinforcement components.

[0063] According to the importance indexes of the elements in the electro-mechanical coupling system, a number of elements in the elements are selected as important elements, the important elements are reinforced in the pre-event stage before the electro-mechanical coupling system encounters an extreme event, specifically, the importance indexes of the elements in the electro-mechanical coupling system are sorted in descending order according to the numerical values, the total number of the reinforced elements in the electro-mechanical coupling system is determined under the condition of considering the reinforcement constraint, and the elements corresponding to the first G importance indexes are selected as the important elements for reinforcement; when the total number of the elements in the electro-mechanical coupling system is greater than or equal to the preset number of reinforced elements H, the total number of the reinforced elements in the electro-mechanical coupling system is equal to the preset number of reinforced elements H.

[0064] All the reinforced elements will not be severely damaged after the extreme event and can be restored to the normal operating state, thereby minimizing the resilience loss caused by the removal of the elements.

[0065] 3) In the case of considering the electrical coupling recovery optimization constraint, a resilience recovery optimization model of the electro-mechanical coupling system is established; a number of elements in the elements in the electro-mechanical coupling system except the important elements constitute a to-be-restored element set, the to-be-restored load data of the electro-mechanical coupling system is obtained in the post-event stage after the electro-mechanical coupling system encounters an extreme event, the to-be-restored load data of the electro-mechanical coupling system is input into the resilience recovery optimization model of the electro-mechanical coupling system, the resilience recovery optimization model of the electro-mechanical coupling system outputs the recovery decision variable of the to-be-restored element set, and a number of elements in the to-be-restored element set are removed according to the recovery decision variable, so that the electrical coupling system realizes resilience recovery, and finally realizes the two-stage element reinforcement and resilience recovery of the electro-mechanical coupling system.

[0066] In step 3), in the case of considering the electrical coupling recovery optimization constraint, the resilience recovery optimization model of the electro-mechanical coupling system is established, specifically as follows:

[0067]

[0068]

[0069]

[0070]

[0071] Wherein, R represents the system resilience index of the electro-mechanical coupling system, T represents the duration of the post-event stage, the duration T of the post-event stage is divided into a number of time periods, N T represents the total number of time periods into which the duration T of the post-event stage is divided; and V represents the functional levels of the power grid and the natural gas grid at time t, respectively, and υ represents the weighting coefficient; e and V g These represent the set of electrical nodes in an electric power network and the set of gas nodes in a natural gas network, respectively. and Let represent the operating state variables of electrical node i in the power grid and gas node j in the natural gas network at time t, respectively. If the operating state of electrical node i in the power grid or gas node j in the natural gas network has been restored at time t, then the operating state variables of electrical node i in the power grid or gas node j in the natural gas network at time t are... or τ equals 1, otherwise equals 0; e,i and τ represents the load shedding cost coefficient and the size of the load to be restored at electrical node i in the power network, respectively; g,j and These represent the load shedding cost coefficient and the load to be restored at gas node j in the natural gas network, respectively. Their product represents the load value at that node; the cost is specifically the amount of electricity or natural gas consumed.

[0072] The specific constraints for electrical coupling restoration optimization are as follows:

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] in, and represents the restoration decision variable of transmission line l in power network, gas pipeline p in gas network and compressor branch c in m period, if the working state of transmission line l in power network, gas pipeline p in gas network or compressor branch c in m period has been restored, the restoration decision variable of transmission line l in power network, gas pipeline p in gas network or compressor branch c in m period equals to 1, otherwise equals to 0, when the restoration decision variable of transmission line l in power network, gas pipeline p in gas network or compressor branch c in m period equals to 0, transmission line l in power network, gas pipeline p in gas network or compressor branch c in the electrical-gas coupling system is removed;E r represents the removed element set, the removed element set is contained in the to-be-restored element set; and represents the working state variable of transmission line l in power network, gas pipeline p in gas network and compressor branch c at time t, if the working state of transmission line l in power network, gas pipeline p in gas network or compressor branch c at time t has been restored, the working state variable of transmission line l in power network, gas pipeline p in gas network or compressor branch c at time t equals to 1, otherwise equals to 0; and represents the restoration decision variable of transmission line l in power network, gas pipeline p in gas network and compressor branch c in m period, if the working state of transmission line l in power network, gas pipeline p in gas network or compressor branch c in m period has been restored, the restoration decision variable of transmission line l in power network, gas pipeline p in gas network or compressor branch c in m period equals to 1, otherwise equals to 0, when the restoration decision variable of transmission line l in power network, gas pipeline p in gas network or compressor branch c in m period equals to 0, transmission line l in power network, gas pipeline p in gas network or compressor branch c in the electrical-gas coupling system is removed;E line , E pipe and E com represents the set of all power lines in all power networks, the set of all gas pipelines in gas network and the set of compressor branches;η gfu,i represents the energy conversion coefficient of gas turbine unit on electric node i in power network; represents the gas-to-electricity load output of gas load device on gas node j in gas network in t period;ρrepresents the calorific value of natural gas; represents the power generation of gas turbine unit on electric node i in power network in t period, and respectively represent the upper limit and the lower limit of the power generation of the gas unit on the electrical node i of the power network in the time period t; represents the working state variable of the gas unit on the electrical node i of the power network at time t, if the resilience of the gas unit on the electrical node i of the power network at time t has been restored, the working state variable of the gas unit on the electrical node i of the power network at time t is equal to 1, otherwise, it is equal to 0. represents the working state variable of the gas unit on the electrical node i of the power network at time t, if the resilience of the gas unit on the electrical node i of the power network at time t has been restored, the working state variable of the gas unit on the electrical node i of the power network at time t is equal to 1, otherwise, it is equal to 0. represents the upper limit of the gas-to-electricity load of the gas load equipment on the gas node j of the natural gas network.

[0083] In step 3), the to-be-restored load data of the electricity-gas coupling system is obtained in the post-event phase after the electricity-gas coupling system encounters an extreme event, the to-be-restored load data of the electricity-gas coupling system includes the to-be-restored load size of the electrical node i of the power network and the to-be-restored load size of the gas node j of the natural gas network The to-be-restored load data of the electricity-gas coupling system is input into the resilience restoration optimization model of the electricity-gas coupling system, and the resilience restoration optimization model of the electricity-gas coupling system outputs the restoration decision variable of the to-be-restored element set, the restoration decision variable of the to-be-restored element set includes the restoration decision variable of the power transmission line l in the power network, the gas transmission pipeline p and the compressor branch c in the natural gas network in the time period t and According to the restoration decision variable, the removal strategy of the elements in the to-be-restored element set is determined, that is, a number of elements in the to-be-restored element set are removed, so that the electricity-gas coupling system realizes resilience restoration, and the elements with high restoration importance are restored first, which can speed up the resilience restoration of the electricity-gas coupling system, and finally realize the two-stage reinforcement and resilience restoration of the electricity-gas coupling system, that is, the element reinforcement in the pre-event phase and the element resilience restoration in the post-event phase.

[0084] The resilience of the electricity-gas coupling system is simulated under extreme events, and the resilience of the electricity-gas coupling system under the method of the present application is evaluated through the expected loss resilience index, which is as follows:

[0085]

[0086] Wherein, ELOR represents the expected loss resilience index; n s represents the total simulation times; represents the removed element set under the σth extreme event simulation; is the resilience loss value of the to-be-restored element set under the σth extreme event simulation.

[0087] The specific implementation of the method of the present application is as follows:

[0088] As Figure 1As shown, taking an electricity-gas coupled system composed of IEEE 30-bus power system and Belgium 20-bus natural gas system as an example, the specific implementation of the present application is described in detail in combination with the technical solutions and the drawings.

[0089] 1) Component importance recognition

[0090] Firstly, the importance of each component in the system is recognized, thereby guiding the pre-stage important component reinforcement strategy. By using the resilience recovery optimization model of the electricity-gas coupled system proposed in the present application, the ideal recovery process and the actual recovery process after removing each component can be solved, and based on this, the importance LOR(ξ) of each component is recognized, wherein the importance of the compressor branch is low and is not listed in the table.

[0091]

[0092] 2) Resilience recovery strategy evaluation results

[0093] Further, the electricity-gas coupled system stage resilience recovery method considering the component importance recognition proposed in the present method is compared with the traditional method. The traditional method usually only considers recovery in the post-stage, and does not consider the priority of each component recovery when recovering. The comparison results are shown in the following table.

[0094]

[0095] As can be seen from the above table, compared with the traditional method, in various scenarios where the number of removed components caused by extreme events is different, the expected resilience loss index of the present method is lower, thereby illustrating that the present method can reduce the resilience loss of the electricity-gas coupled system under the influence of extreme weather.

Claims

1. A two-stage resilience recovery method for an electrically coupled system considering component importance recognition, characterized in that: The method comprises the following steps: 1) establishing an electro-gas coupling system comprising a plurality of elements, obtaining a system function level of the electro-gas coupling system after removal of each element of the electro-gas coupling system, and obtaining an importance index of each element of the electro-gas coupling system according to the system function level of the electro-gas coupling system after removal of each element, specifically as follows: wherein denotes an importance index of an element in the electro-mechanical coupling system; and denote a start time and an end time of a resilience recovery process of an element in the electro-mechanical coupling system, respectively; denotes a time at which a desired system function level of the electro-mechanical coupling system, i.e. the electro-mechanical coupling system at time has recovered a load level; denotes a time at which a system function level of the electro-mechanical coupling system; denotes a time at which an element in the electro-mechanical coupling system has been removed, a system function level of the electro-mechanical coupling system;​​ 2) selecting a plurality of elements of each element as important elements in the electro-gas coupling system according to the importance index of each element of the electro-gas coupling system, and reinforcing each important element in a pre-event stage before the electro-gas coupling system encounters an extreme event, considering the reinforcement constraints; 3) establishing a resilience recovery optimization model of the electro-gas coupling system, considering the electro-gas coupling recovery optimization constraints, specifically as follows: wherein, represents a system resilience indicator of the electro-gas coupled system, represents a duration of the post-contingency phase, the duration of the post-contingency phase is divided into a number of time periods, represents a duration of the post-contingency phase is divided into a number of time periods; and respectively represent the power network functionality level and the gas network functionality level at time t, represents a weight coefficient; and respectively represent a set of electrical nodes of the power network and a set of gas nodes of the gas network; and respectively represent an electrical node of the power network and a gas node of the gas network at time t, the working state variable of the electrical node of the power network or the gas node of the gas network at time t, if the working state of the electrical node of the power network or the gas node of the gas network at time t has recovered, the working state variable of the electrical node of the power network or the gas node of the gas network at time t is equal to 1, otherwise is equal to 0; or represents a cut load cost coefficient and a to-be-restored load size on the electrical node of the power network and represents a cut load cost coefficient and a to-be-restored load size on the gas node of the gas network ; and and represents a cut load cost coefficient and a to-be-restored load size on the gas node of the gas network ; and constructing a set of to-be-recovered elements from a plurality of elements other than the important elements in each element of the electro-gas coupling system, obtaining to-be-recovered load data of the electro-gas coupling system in a post-event stage after the electro-gas coupling system encounters an extreme event, inputting the to-be-recovered load data of the electro-gas coupling system into the electro-gas coupling system resilience recovery optimization model, and outputting recovery decision variables of the set of to-be-recovered elements from the electro-gas coupling system resilience recovery optimization model, removing a plurality of elements from the set of to-be-recovered elements according to the recovery decision variables, so that the electro-gas coupling system realizes resilience recovery, and finally realizes two-stage element reinforcement and resilience recovery of the electro-gas coupling system.

2. The two-stage resilience recovery method of an electrical coupling system considering component importance recognition according to claim 1, characterized in that: In the step 1), the electro-gas coupling system comprises a power network and a natural gas network, the power network comprises a plurality of electric nodes, generator sets, substations and electric load devices, the electric nodes are connected by a plurality of power transmission lines, the generator sets, the substations and the electric load devices are located at the respective electric nodes, each generator set comprises a gas turbine unit and a non-gas turbine unit, and each electric load device comprises an electric load device consuming electric load and an electric load device consuming converted gas load; the natural gas network comprises a plurality of gas nodes, gas source devices, compressor devices and gas load devices, the gas nodes are connected by a plurality of gas transmission pipelines, the gas source devices and the gas load devices are located at the respective gas nodes, each gas source device comprises a gas source and an electric-gas conversion device, and each gas load device comprises a gas load device consuming gas load and a gas load device consuming converted electric load; the natural gas network further comprises a plurality of compressor branches, each compressor branch has a compressor device arranged thereon and is connected to one gas node at each end; each electric node where the gas turbine unit of the power network is located is connected to each gas node where the electric load device consuming converted gas load of the natural gas network is located; and each gas node where the electric-gas conversion device of the natural gas network is located is connected to each electric node where the electric load device consuming converted gas load of the power network is located. Each element in the electro-gas coupling system comprises each power transmission line in the power network and each gas transmission pipeline and each compressor branch in the natural gas network.

3. The two-stage resilience recovery method of an electrical coupling system considering component importance recognition according to claim 2, characterized in that: In the step 2), the reinforcement constraints are specifically as follows: wherein, represents the total number of hardened elements in the electro- pneumatic coupling system, represents a hardening decision variable for an element in the electro-pneumatic coupling system, if the element is hardened, the hardening decision variable , otherwise ; is a preset number of hardened elements; According to the importance indexes of the elements in the electric-gas coupling system, in the case of considering reinforcement constraints, a plurality of elements in the elements are selected as important elements, the important elements are reinforced in a pre-event stage before the electric-gas coupling system encounters an extreme event, specifically, the importance indexes of the elements in the electric-gas coupling system are sorted from large to small according to the numerical values, in the case of considering reinforcement constraints, the total number of the reinforced elements in the electric-gas coupling system is determined , the elements of the first importance indexes in the sorting are selected as the important elements for reinforcement.

4. The two-stage resilience recovery method of an electrical coupling system considering component importance recognition according to claim 2, characterized in that: In the step 3), the electro-gas coupling recovery optimization constraints are specifically as follows: wherein , and represent transmission lines in the power network , gas pipelines in the gas network and compressor branches , the restoration decision variable of the time period, if the working state of the transmission line in the power network , the gas pipeline in the gas network or the compressor branch has been restored in the time period , the restoration decision variable of the transmission line in the power network , the gas pipeline in the gas network or the compressor branch in the time period equals 1, otherwise equals 0, when the restoration decision variable of the transmission line in the power network , the gas pipeline in the gas network or the compressor branch in the time period equals 0, the transmission line in the power network , the gas pipeline in the gas network or the compressor branch is removed in the electro-gas coupling system; represents the removed element set, the removed element set is contained in the to-be-restored element set; , and represent the working state variable of the transmission line in the power network , the gas pipeline in the gas network and the compressor branch at the time point , if the working state of the transmission line in the power network , the gas pipeline in the gas network or the compressor branch has been restored at the time point , the working state variable of the transmission line in the power network , the gas pipeline in the gas network or the compressor branch at the time point equals 1, otherwise equals 0; , and represent the working state variable of the transmission line in the power network , the gas pipeline in the gas network and the compressor branch at the time point recovery decision variable for transmission lines in the power network , gas pipelines in the natural gas network or compressor branches in the time period recovery decision variable for transmission lines in the power network , gas pipelines in the natural gas network or compressor branches in the time period recovery decision variable equals 1, otherwise equals 0, when the recovery decision variable for transmission lines in the power network , gas pipelines in the natural gas network or compressor branches in the time period recovery decision variable equals 0, the transmission lines in the power network , gas pipelines in the natural gas network or compressor branches are removed in the electro-gas coupled system; , and denote the set of all power lines in the power network, the set of all gas pipelines in the natural gas network and the set of compressor branches, respectively; denotes the energy conversion coefficient of the gas unit at the electrical node of the power network; denotes the gas-to-electricity load output of the gas load device consuming the electricity-to-gas load at the gas node denotes the heat value of natural gas; denotes the electricity generation power of the gas unit at the electrical node and denote the upper and lower bounds of the electricity generation power of the gas unit at the electrical node denotes the operation state variable of the gas unit at the electrical node of the power network at time , if the resilience of the gas unit at the electrical node of the power network has recovered at time , the operation state variable of the gas unit at the electrical node of the power network at time equals 1, otherwise equals 0; denotes the upper bound of the gas-to-electricity load of the gas load device consuming the electricity-to-gas load at the gas node of the natural gas network.

5. The two-stage resilience recovery method of an electrical coupling system considering component importance recognition according to claim 4, characterized in that: The step 3) obtains the to-be-restored load data of the electric-gas coupling system in the post-event stage after the electric-gas coupling system encounters an extreme event, the to-be-restored load data of the electric-gas coupling system includes the to-be-restored load size of the electric node of the power network and the to-be-restored load size of the gas node of the natural gas network ; the to-be-restored load data of the electric-gas coupling system is input into the electric-gas coupling system resilience restoration optimization model, the electric-gas coupling system resilience restoration optimization model outputs the restoration decision variable of the to-be-restored element set, the restoration decision variable of the to-be-restored element set includes the restoration decision variable of the transmission line in the power network , the restoration decision variable of the gas pipeline and the restoration decision variable of the compressor branch in the time period , and , according to the restoration decision variable, the removal strategy of the elements in the to-be-restored element set is determined, that is, the removal of a plurality of elements in the to-be-restored element set is determined, so that the electric-gas coupling system realizes resilience restoration, and finally realizes the reinforcement and resilience restoration of the electric-gas coupling system in two stages, that is, the element reinforcement in the pre-event stage and the element resilience restoration in the post-event stage.

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