Power grid toughness evaluation method for urban system function requirements under earthquake disasters

Abstract

The invention discloses a power grid toughness evaluation method for urban system function requirements under earthquake disasters, and the method comprises the following steps: building a three-stage division model of a potential seismic source region according to the non-complete random distribution of earthquake activities in space, and determining the probability distribution conditions of earthquakes of different magnitudes in the potential seismic source region; seismic oscillation peak accelerations under different epicentral distances are obtained by adopting a seismic attenuation elliptical model, and then a fault probability model of surface elements and buried pipelines under a seismic scene is constructed; based on the power characteristics of a water pumping station, a compressor and a gas turbine, constructing an urban water supply network model and an urban gas supply network model which are influenced by the power supply capacity of the power grid; constructing a distribution network reconstruction and island division-based power grid toughness recovery model which comprehensively considers urban lifeline system function requirements under earthquake disasters; the basic living needs of victims are met to the maximum extent under limited power resources, and then the toughness of an urban power grid facing earthquake disasters is measured.

Description

Technical Field

[0001] The present invention relates to the technical field of urban water supply and electricity grid, and in particular to a grid resilience assessment method for urban system functional requirements under earthquake disasters. Background Art

[0002] As a whole, the normal operation of the urban system requires the mutual cooperation of multiple urban lifeline systems such as the power grid, water supply network, and gas supply network. While each system plays its own role, there is also a coupling relationship. As the energy provider of the urban system, the power grid plays a key supporting role in the operation of the urban lifeline system. The failure of the power grid will directly affect the operation status of other systems. However, in recent years, extreme disasters such as earthquakes have brought great risks to the stable and reliable operation of the power system. In the 8.0 magnitude earthquake, at least 1,700 10kV lines, 106 35kV lines, 118 110kV lines, and 46 220kV lines were shut down, the total network load loss exceeded 4 million kW, and at least 2.46 million users were without power, causing huge economic losses and adverse social impacts.

[0003] Basic resources such as water, electricity, and gas play an important role in restoring basic living order in disaster areas and carrying out rescue and relief work. Therefore, when evaluating the losses of urban power grids in the face of earthquake disasters, it is necessary not only to consider the load loss caused by power grid failures under earthquakes, but also to comprehensively evaluate the functional losses of urban lifeline systems caused by power grid failures. At this time, the resilience requirements for urban power grids will not be limited to power restoration, but it is necessary to comprehensively consider the restoration of the functional requirements of urban lifeline systems.

[0004] At present, the assessment of the resilience of urban power grids under earthquake disasters mainly starts from the perspective of minimizing the amount of power grid load loss. However, the functionality of the urban lifeline system and the energy coupling of the power grid are not a simple linear relationship, and the energy demand within each urban lifeline system is not a superposition relationship. In the scenario of power shortage caused by earthquake disasters, the maximum recovery of electricity cannot improve the degree of recovery of the functions of the urban lifeline system, but may waste precious electricity resources. Therefore, it is necessary to consider the differences in resource requirements of different types of users to more accurately reflect the resilience of urban power grids in the face of earthquake disasters. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a grid resilience assessment method for urban system functional requirements under earthquake disasters, which comprehensively considers the needs of different types of disaster-stricken users for basic resources such as water, electricity, and gas under limited power resources, and satisfies the basic living needs of the affected people to the greatest extent, thereby measuring the resilience of urban power grids in the face of earthquake disasters.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] A method for evaluating the resilience of a power grid based on the functional requirements of an urban system under earthquake disasters comprises the following steps:

[0008] S101. Based on the non-completely random distribution of earthquake activity in space, a three-level division model of potential earthquake source areas is established to determine the probability distribution of earthquakes of different magnitudes occurring in the potential earthquake source areas;

[0009] S102, obtaining the peak acceleration of earthquake motion at different epicenter distances by adopting an earthquake attenuation ellipse model, and then constructing a failure probability model of surface components and buried pipelines under an earthquake scenario;

[0010] S103. Based on the power characteristics of the water pump station, the compressor and the gas turbine, a city water supply network model and a city gas supply network model affected by the power supply capacity of the power grid are constructed;

[0011] S104. Based on the objective function, decision variables and condition constraint library, a power grid resilience recovery model is constructed under earthquake disasters based on distribution network reconstruction and island division, which comprehensively considers the functional requirements of the urban lifeline system.

[0012] Furthermore, according to the non-completely random distribution of earthquake activity in space, a three-level division model of potential earthquake source areas is established, and the probability distribution of earthquakes of different magnitudes occurring in the potential earthquake source areas is determined, including the following steps:

[0013] The seismic activity area is divided into the first-level seismic statistical area, the second-level seismic tectonic area and the third-level potential earthquake source area;

[0014] The magnitude is divided into different levels of magnitude gears, and the probability of earthquake occurrence in each magnitude gear in the earthquake statistical area is calculated. The expression is as follows:

[0015]

[0016] Among them, P earthquake (M i ) is the probability of an earthquake of the i-th magnitude occurring in the earthquake statistical area; M0 is the magnitude of the earthquake in the earthquake statistical area; ΔM is the interval between each magnitude level, which is set to 0.5; β is the GR relationship coefficient of the earthquake statistical area, which represents the quantitative relationship between the earthquake level and the number of occurrences in the statistical area, M UA is the maximum magnitude of the earthquake in the earthquake statistical area, M i is the i-th magnitude earthquake in the earthquake statistical area;

[0017] Based on the number and spatial distribution of scattered points in the earthquake statistical area, M i The probability of an earthquake of this magnitude occurring in each potential source area is expressed as follows:

[0018]

[0019] Among them, P occur ((x,y)|M i ) j Indicates M i The probability of an earthquake of this magnitude occurring in the jth potential source area; N j is the number of scattered points in the jth potential earthquake source area, N k is the number of scattered points in the kth potential earthquake source area, M Uj is the maximum magnitude of the jth potential earthquake source area, M Uk is the maximum magnitude of the kth potential earthquake source area, μ j is a Boolean constant. When M i Located between M0 and M Uj When between, take 1, M i Greater than M Uj When 0 is taken;

[0020] Based on the probability of earthquake occurrence in each magnitude range in the earthquake statistical area and M i The probability of an earthquake of magnitude M occurring in each potential source area is determined by x Greater than M i The probability of an event is expressed as follows:

[0021] P j (M x ≥M i )=P earthquake (M i )·P occur ((x,y)|M i ) j

[0022] Among them, P earthquake (M i ) is the probability of an earthquake of magnitude i occurring in the earthquake statistical area, P occur ((x,y)|M i ) j Indicates M i The probability of an earthquake of this magnitude occurring in the jth potential source area.

[0023] Furthermore, the earthquake attenuation ellipse model is used to obtain the peak acceleration of the earthquake motion at different epicenter distances, and then the failure probability model of the surface components and the buried pipeline under the earthquake scene is constructed, which includes the following steps:

[0024] The earthquake magnitude is segmented to construct the attenuation of earthquake motion parameters in different magnitude ranges, and the peak acceleration of earthquake motion is determined based on the magnitude and epicenter distance of the earthquake;

[0025] The failure probability of the ground surface components is described by adopting the fragility model, which is expressed as follows:

[0026]

[0027] in, For k element in Y PGA The probability of being in the jth damage state under the peak acceleration of the earthquake motion; represents the sequence number of the four damage states, j=1~4 represents slight damage, moderate damage, severe damage and complete damage respectively; are the median and standard deviation of the fragility curves of the four damage states;

[0028] Since the probability of buried pipeline failure is affected by factors such as geology, pipe diameter, seismic intensity and pipeline length, the buried pipeline failure probability model is obtained by combining the simplified model of pipeline segment seismic damage rate with the seismic motion parameters and seismic intensity conversion formula. Its expression is as follows:

[0029]

[0030] P pipe =1-exp(-R f ·L)

[0031] Among them, R f is the seismic damage rate of underground pipeline sections; C d is the underground pipeline diameter coefficient; C g is the geological coefficient; P pipe is the probability of serious damage to the buried pipeline, and L is the length of the buried pipeline.

[0032] Furthermore, the urban water supply network model includes a node head constraint model, a water pipe flow model, a water pump operation status model and a water pump and power grid energy coupling relationship model.

[0033] Furthermore, the urban gas supply network model includes a node gas pressure constraint model, a gas supply network flow model, a compressor operation status model, a compressor energy coupling model and a gas turbine energy coupling model.

[0034] Furthermore, based on the objective function, decision variables and condition constraint library, a grid resilience recovery model based on distribution network reconstruction and island division under earthquake disasters that comprehensively considers the functional requirements of the urban lifeline system is constructed, including the following steps:

[0035] In the earthquake disaster scenario, according to the demand of each user for electricity, water and gas resources, the functional loss of the entire city lifeline system in the earthquake scenario can be reduced. The expression is as follows:

[0036]

[0037] Among them, α i +β i +γ i =1, ω i is the importance weight of user i; α i , β i , γ i are the demand ratio parameters for electricity resources, water resources, and gas resources in the energy structure of user i, respectively. For the same user i, α i , β i , γ i The sum is 1; are the amount of electricity, water and gas resources restored by user i in period t under the disaster scenario; are the electricity, water and gas resource demands of user i in period t under normal circumstances; Ω is the set of all users;

[0038] The main grid and the distribution grid exchange electric power through the tie line. When the main grid transmits power to the distribution grid, it takes positive value, otherwise it takes negative value. The present invention only considers the scenario of power transmission from the main grid to the distribution grid.

[0039] Construct the main distribution network power interaction constraint model, and its expression is as follows:

[0040]

[0041] in, are respectively the active and reactive power transmitted by the tie line received by node i in the distribution network at time t; are the upper limits of active and reactive power transmitted by the tie line received by node i in the distribution network at time t, respectively; are the lower limits of active and reactive power transmitted by the tie line received by node i in the distribution network at time t, respectively; and They are respectively the active and reactive power of the load on the main grid node j at time t; and are the power transmitted from the main grid to the distribution grid through the tie line; and They are respectively the active and reactive power generated by the main grid power supply node; and are the active and reactive power cut on the main grid node j at time t respectively;

[0042] Based on the binary variables of power transmitted between nodes, square value of current amplitude transmitted between nodes, square value of voltage amplitude between nodes, impedance of lines between nodes and connectivity status between nodes, a distribution network operation model is constructed, and its expression is as follows:

[0043]

[0044]

[0045] in, is the active power transmitted from node i to node j at time t; is the active power demand of residents at node i at time t; is the proportion of active power recovery of residents at node i at time t; r ki is the resistance value of the line between node k and node i; is the reactive power transmitted from node i to node j at time t; is the reactive power demand of residents at node i at time t; ki is the reactance value of the line between node k and node i; is the square value of the current amplitude transmitted from node k to node i at time t; is the square of the voltage amplitude at node i at time t; is a binary variable indicating the connectivity status between node i and node j at a given moment. If the connection is connected, it takes 1, otherwise it takes 0. M is a sufficiently large positive number.

[0046] Construct voltage safety operation constraints and current safety operation constraints;

[0047] Construct radial constraints for distribution networks.

[0048] The beneficial effects of the present application are: it fully takes into account the non-completely random distribution characteristics of earthquake disasters, establishes a three-level division model for potential earthquake source areas, establishes the probability distribution of earthquakes of different magnitudes occurring in potential earthquake source areas, and uses the PGA seismic peak acceleration as an earthquake attenuation indicator to more accurately reflect the attenuation of high-magnitude earthquakes.

[0049] The city system is considered as a whole, and the supporting role and coupling relationship of the power grid to the city lifeline system are fully considered. After the power grid is damaged by an earthquake disaster, its impact on the city lifeline system and the loss of functions of different types of users are used to measure the resilience of the power grid under earthquake disasters.

[0050] It is possible to consider the differences in resource demands of different types of users in scenarios where electricity shortages are caused by earthquake disasters, and to more accurately set up a resilience recovery model for urban power grids in the face of earthquake disasters. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 It is a schematic diagram of the steps of a method for evaluating the resilience of a power grid according to the functional requirements of a city system under earthquake disasters according to the present invention;

[0053] Figure 2 It is a schematic diagram of the three-level division model of the potential earthquake source area of ​​the present invention;

[0054] Figure 3 It is a schematic diagram of the distribution of earthquake sources of various magnitudes in the potential earthquake source area of ​​the present invention;

[0055] Figure 4 This is an exemplary application scenario of the power supply network of the present invention;

[0056] Figure 5 This is an exemplary application scenario of the water supply network of the present invention;

[0057] Figure 6 This is an exemplary application scenario of the gas supply network of the present invention;

[0058] Figure 7 It is a comparison of the residential electricity recovery situation of the present invention;

[0059] Figure 8 It is a comparison of the recovery of the residential gas load of the present invention;

[0060] Fig. 9 It is a comparison of the recovery of the water load of residents in the present invention. DETAILED DESCRIPTION

[0061] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0062] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0063] Embodiment 1:

[0064] A method for evaluating the resilience of a power grid based on the functional requirements of an urban system under earthquake disasters comprises the following steps:

[0065] S101. Based on the non-completely random distribution of earthquake activity in space, a three-level division model of potential earthquake source areas is established to determine the probability distribution of earthquakes of different magnitudes occurring in the potential earthquake source areas;

[0066] The three-level classification model of potential earthquake source areas is as follows Figure 2 As shown in the figure, it is divided into three layers and five zones. The bottom layer A is the seismic zone, that is, the first-level seismic statistical zone; the middle layer A1 and A2 are the second-level seismic tectonic zones; the upper layer A 11 With A 21 The potential earthquake source area is divided into three levels. U It represents the maximum magnitude in each area. The maximum magnitude in the earthquake statistical area is the maximum possible magnitude in the earthquake belt, that is, The maximum magnitude of a potential earthquake source area is less than the maximum magnitude of the earthquake in the seismic tectonic zone where it is located, that is, and

[0067] According to the non-completely random distribution of seismic activity in space, a three-level division model of potential earthquake source areas is established to determine the probability distribution of earthquakes of different magnitudes occurring in the potential earthquake source areas, including the following steps:

[0068] The seismic activity area is divided into the first-level seismic statistical area, the second-level seismic tectonic area and the third-level potential earthquake source area;

[0069] The magnitude is divided into different levels of magnitude gears, and the probability of earthquake occurrence in each magnitude gear in the earthquake statistical area is calculated. The expression is as follows:

[0070]

[0071] Among them, P earthquake (M i ) is the probability of an earthquake of the i-th magnitude occurring in the earthquake statistical area; M0 is the magnitude of the earthquake in the earthquake statistical area; ΔM is the interval between each magnitude level, which is set to 0.5; β is the GR relationship coefficient of the earthquake statistical area, which represents the quantitative relationship between the earthquake level and the number of occurrences in the statistical area, M UA is the maximum magnitude of the earthquake in the earthquake statistical area, M i is the i-th magnitude earthquake in the earthquake statistical area;

[0072] Based on the number and spatial distribution of scattered points in the earthquake statistical area, M i The probability of an earthquake of this magnitude occurring in each potential source area is expressed as follows:

[0073]

[0074] Among them, P occur ((x,y)M i )j Indicates M i The probability of an earthquake of this magnitude occurring in the ,th potential source area; N j is the number of scattered points in the potential source area, N k is the number of scattered points in the kth potential earthquake source area, M Uj is the maximum magnitude of the potential source area, M Uk is the maximum magnitude of the kth potential earthquake source area, μ j is a Boolean constant. When M i Located between M0 and M Uj When between, take 1, M i Greater than M Uj When 0 is taken;

[0075] Based on the probability of earthquake occurrence in each magnitude range in the earthquake statistical area and M i The probability of an earthquake of magnitude M occurring in each potential source area is determined by x Greater than M i The probability of an event is expressed as follows:

[0076] P j (M x ≥M i )=P earthquake (M i )·P occur ((x,y)|M i ) j

[0077] Among them, P earthauake (M i ) is the probability of an earthquake of magnitude i occurring in the earthquake statistical area, P occur ((x,y)M i ) j Indicates M i The probability of an earthquake of this magnitude occurring in the jth potential source area.

[0078] It should be noted that the division of seismic activity zones into first-level seismic statistical zones, second-level seismic tectonic zones and third-level potential earthquake source zones, and simply increasing or decreasing the number of seismic activity zone divisions are all within the protection scope of this application.

[0079] S102, obtaining the peak acceleration of earthquake motion at different epicenter distances by adopting an earthquake attenuation ellipse model, and then constructing a failure probability model of surface components and buried pipelines under an earthquake scenario;

[0080] The earthquake intensity attenuation model currently widely used can show good results when facing earthquakes of magnitude 4 to 7, but when facing high-magnitude earthquakes, the intensity value will be underestimated to a certain extent due to weak constraints. Using seismic motion parameters to reflect the attenuation relationship of earthquakes can largely solve this problem. For example, using magnitude 6.5 as the dividing line, the magnitude is segmented and the attenuation of seismic motion parameters of different magnitude ranges is constructed. When M≤6.5: lg(Y PGA )=0.561+0.746M-1.925·lg(L+0.956·exp(0.462·M)); when M≥6.5: lg(Y PGA )=2.501+0.448M-1.925·lg(L+0.956·exp(0.462·M)); where M is the magnitude of the earthquake; L is the distance from the epicenter; Y PGA It is the peak ground acceleration PGA. In the face of earthquakes of different levels, the damage can be divided into: slight damage, moderate damage, moderate damage and complete damage.

[0081] The earthquake attenuation ellipse model is used to obtain the peak acceleration of the earthquake motion at different epicenter distances, and then the failure probability model of the surface components and buried pipelines under the earthquake scenario is constructed, which includes the following steps:

[0082] The earthquake magnitude is segmented to construct the attenuation of earthquake motion parameters in different magnitude ranges, and the peak acceleration of earthquake motion is determined based on the magnitude and epicenter distance of the earthquake;

[0083] The failure probability of the ground surface components is described by adopting the fragility model, which is expressed as follows:

[0084]

[0085] in, For k element in Y PGA The probability of being in the jth damage state under the peak acceleration of the earthquake motion; represents the sequence number of the four damage states, j=1~4 represents slight damage, moderate damage, severe damage and complete damage respectively; are the median and standard deviation of the fragility curves of the four damage states;

[0086] Since the probability of buried pipeline failure is affected by factors such as geology, pipe diameter, seismic intensity and pipeline length, the buried pipeline failure probability model is obtained by combining the simplified model of pipeline segment seismic damage rate with the seismic motion parameters and seismic intensity conversion formula. Its expression is as follows:

[0087]

[0088] P pipe =1-exp(-R f ·L)

[0089] Among them, R f is the seismic damage rate of underground pipeline sections; C d is the underground pipeline diameter coefficient; C g is the geological coefficient; P pipe is the probability of serious damage to the buried pipeline, and L is the length of the buried pipeline.

[0090] S103. Based on the power characteristics of the water pump station, the compressor and the gas turbine, a city water supply network model and a city gas supply network model affected by the power supply capacity of the power grid are constructed;

[0091] Urban water supply systems are usually composed of water sources, water storage units, water pump units, and water pipelines. As the carrier of water resource flow, the water pipeline can be regarded as the edge that connects the units of the entire water supply system in series. The water source, water storage unit, and water pump unit can be regarded as the key nodes in the water supply system, thereby simplifying the entire water supply system into a topological structure composed of points and edges. The urban water supply network model includes a node head constraint model, a water pipe flow model, a water pump operation status model, and a water pump and power grid energy coupling relationship model.

[0092] The expression of the node head constraint model is as follows:

[0093]

[0094] Among them, s jk The resistance coefficient of the pipe section can be expressed as l is the length of the pipe section; C w is the Hezen-Williams coefficient; D is the pipe diameter; m is the constant coefficient; For Node j of water head; is the water head at node k; is the head loss between adjacent nodes j and k, which can be expressed as the pipe resistance coefficient and the pipe flow rate function.

[0095] The expression of the water pipe flow model is as follows:

[0096]

[0097] in, h is the upper limit of the flow rate of the pipe section between adjacent nodes; j The lower limit of the node head; is the water load demand at node j; It is the collection of all water network nodes.

[0098] The pump operation state model expression is as follows:

[0099]

[0100] in, is a binary variable of the start and stop state of the water pump, which takes 1 when the water pump is in operation and 0 otherwise; α, β are characteristic parameters of the water pump; is the set of pipes affected by the operating state of pump m; Ω pump A collection of all pumps.

[0101] The expression of the energy coupling relationship model between the water pump and the power grid is as follows:

[0102]

[0103] in, is the power consumed by the water pump m at time t; ρ is the density of water; g is the acceleration due to gravity; is the power factor of the water pump m; is the flow rate of the pipeline where the water pump m is located; is the upper limit of the power of the water pump unit m;

[0104] The urban gas supply system is usually composed of gas sources, gas pipelines, compressors, and gas turbines. The compressors and gas turbines consume and generate electricity respectively, making the power grid and gas grid present a two-way flow relationship in terms of energy. In the case of limited resources in disaster scenarios, resources can be better allocated. The urban gas supply network model includes a node pressure constraint model, a gas supply network flow model, a compressor operation status model, a compressor energy coupling model, and a gas turbine energy coupling model.

[0105] The expression of the node air pressure constraint model is as follows:

[0106]

[0107] Among them, K jk is the Weymouth characteristic parameter of the natural gas pipeline; is the node air pressure of gas network node j at time t; p j and are the lower and upper limits of the air pressure at node j in the gas network, respectively.

[0108] The expression of the gas network flow model is as follows:

[0109]

[0110] in, is the flow rate of the pipe section between adjacent nodes; is the gas load demand at node j; is the gas consumption of the gas turbine at node j; The collection of all gas network nodes.

[0111] The expression of the compressor operation state model is as follows:

[0112]

[0113] in, is a binary variable of the compressor start / stop state, which takes 1 when the compressor is in operation and 0 otherwise; λ is the compression ratio of the compressor; is the set of pipelines affected by the operating state of compressor n; Ω comp The collection of all compressors.

[0114] The expression of the compressor energy coupling model is as follows:

[0115]

[0116] in, is the power consumed by compressor n at time t; is the conversion coefficient between gas flow and power consumption;

[0117] The expression of the gas turbine energy coupling model is as follows:

[0118]

[0119] in, is the power generation of gas turbine l at time t; is the conversion factor between gas consumption and power generation;

[0120] S104. Based on the objective function, decision variables and condition constraint library, a power grid resilience recovery model based on distribution network reconstruction and island division under earthquake disasters is constructed to comprehensively consider the functional requirements of the urban lifeline system;

[0121] The maximum sum of functional recovery degrees of water, electricity and gas resources of different types of users in the city is taken as the objective function, and the amount of user life electricity recovery, water pump station operation power consumption, compressor boosting power consumption and gas consumption of gas turbine power generation are taken as decision variables. According to the main grid power transmission constraint, power and electricity balance constraint, voltage safe operation constraint, current safe operation constraint, distribution network radial constraint, water source constraint, gas source constraint and the node head constraint constructed in step S103, water network pipeline flow upper limit constraint, node gas pressure constraint and other constraints, a power grid resilience recovery model that comprehensively considers the functional requirements of the city lifeline system under earthquake disasters based on distribution network reconstruction and island division is constructed. A conditional constraint library is constructed, which includes the main grid power transmission constraint, power and electricity balance constraint, voltage safe operation constraint, current safe operation constraint, distribution network radial constraint, water source constraint, gas source constraint, node head constraint, water network pipeline flow upper limit constraint, and node gas pressure constraint.

[0122] Based on the objective function, decision variables and condition constraint library, a grid resilience recovery model based on distribution network reconstruction and island division under earthquake disasters that comprehensively considers the functional requirements of the urban lifeline system includes the following steps:

[0123] In the earthquake disaster scenario, according to the demand of each user for electricity, water and gas resources, the functional loss of the entire city lifeline system in the earthquake scenario can be reduced. The expression is as follows:

[0124]

[0125] Among them, α i +β i +γ i =1, ω i is the importance weight of user i; α i , β i , γ i are the demand ratio parameters for electricity resources, water resources, and gas resources in the energy structure of user i, respectively. For the same user i, α i , β i , γ i The sum is 1; are the amount of electricity, water and gas resources restored by user i in period t under the disaster scenario; are the electricity, water and gas resource demands of user i in period t under normal circumstances; Ω is the set of all users;

[0126] The main grid and the distribution grid exchange electric power through the tie line. When the main grid transmits power to the distribution grid, it takes positive value, otherwise it takes negative value. The present invention only considers the scenario of power transmission from the main grid to the distribution grid.

[0127] Construct the main distribution network power interaction constraint model, and its expression is as follows:

[0128]

[0129] in, are respectively the active and reactive power transmitted by the tie line received by node i in the distribution network at time t; are the upper limits of active and reactive power transmitted by the tie line received by node i in the distribution network at time t, respectively; are the lower limits of active and reactive power transmitted by the tie line received by node i in the distribution network at time t, respectively; and They are respectively the active and reactive power of the load on the main grid node j at time t; and are the power transmitted from the main grid to the distribution grid through the tie line; and They are respectively the active and reactive power generated by the main grid power supply node; and are the active and reactive power cut on the main grid node j at time t respectively;

[0130] Based on the binary variables of power transmitted between nodes, square value of current amplitude transmitted between nodes, square value of voltage amplitude between nodes, impedance of lines between nodes and connectivity status between nodes, a distribution network operation model is constructed, and its expression is as follows:

[0131]

[0132] in, is the active power transmitted from node i to node j at time t; is the active power demand of residents at node i at time t; is the proportion of active power recovery of residents at node i at time t; r ki is the resistance value of the line between node k and node i; is the reactive power transmitted from node i to node j at time t; is the reactive power demand of residents at node i at time t; ki is the reactance value of the line between node k and node i; is the square value of the current amplitude transmitted from node k to node i at time t; is the square of the voltage amplitude at node i at time t; is a binary variable indicating the connectivity status between node i and node j at a given moment. If the connection is positive, it takes 1; otherwise, it takes 0. M is a sufficiently large positive number.

[0133] Construct voltage safety operation constraints and current safety operation constraints, whose expressions are as follows:

[0134]

[0135] in, U i and are the lower and upper limits of the square value of the voltage amplitude at node i at time t respectively; The upper limit of the square value of the current amplitude transmitted from node i to node j.

[0136] Construct the radial constraint of the distribution network, and its expression is as follows:

[0137]

[0138] Among them, |Ω E | is the total number of nodes in the distribution network; is the virtual power flow between lines ki at time t; is the virtual load demand at node i at time t, and is set to 1 at non-root nodes;

[0139] The main grid and the distribution grid exchange electric power through the tie line. The transmission power of the tie line at node i at time t can be expressed as When the main grid transmits power to the distribution grid, it takes positive value, otherwise it takes negative value; in, is the upper limit of the transmission power of the tie line at node i.

[0140] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0141] The terms "first", "second" and "third" etc. in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in a sequence other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0142] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0143] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating the resilience of a power grid based on the functional requirements of an urban system under earthquake disasters, characterized in that: The following steps are involved: S101. Based on the non-completely random distribution of earthquake activity in space, a three-level division model of potential earthquake source areas is established to determine the probability distribution of earthquakes of different magnitudes occurring in the potential earthquake source areas; S102, obtaining the peak acceleration of earthquake motion at different epicenter distances by adopting an earthquake attenuation ellipse model, and then constructing a failure probability model of surface components and buried pipelines under an earthquake scenario; S103. Based on the power characteristics of the water pump station, the compressor and the gas turbine, a city water supply network model and a city gas supply network model affected by the power supply capacity of the power grid are constructed; S104. Based on the objective function, decision variables and condition constraint library, a power grid resilience recovery model is constructed under earthquake disasters based on distribution network reconstruction and island division, which comprehensively considers the functional requirements of the urban lifeline system.

2. The method for evaluating the resilience of power grids according to the functional requirements of urban systems under earthquake disasters according to claim 1 is characterized in that: The method of establishing a three-level classification model of potential earthquake source areas according to the non-completely random distribution of earthquake activities in space and determining the probability distribution of earthquakes of different magnitudes occurring in the potential earthquake source areas comprises the following steps: The seismic activity area is divided into the first-level seismic statistical area, the second-level seismic tectonic area and the third-level potential earthquake source area; The magnitude of earthquakes is divided into different levels of magnitude gears, and the probability of earthquake occurrence in each magnitude gear in the earthquake statistical area is calculated; Based on the number and spatial distribution of scattered points in the earthquake statistical area, M i The probability of an earthquake of this magnitude occurring in each potential source area; Based on the probability of earthquake occurrence in each magnitude range in the earthquake statistical area and M i The probability of an earthquake of magnitude M occurring in each potential source area is determined by x Greater than M i The probability of an event is expressed as follows: P j (M x ≥M i )=P earthquake (M i )·P occur ((x,y)|M i ) j Among them, P earthquake (M i ) is the probability of an earthquake of magnitude i occurring in the earthquake statistical area, P occur ((x,y)|M i ) j Indicates M i The probability of an earthquake of this magnitude occurring in the jth potential source area.

3. The method for evaluating the resilience of a power grid based on the functional requirements of an urban system under earthquake disasters according to claim 2 is characterized in that: The magnitude is divided into different levels of magnitude gears, and the probability of earthquake occurrence in each magnitude gear in the earthquake statistical area is calculated. The expression is as follows: Among them, P earthquake (M i ) is the probability of an earthquake of the i-th magnitude occurring in the earthquake statistical area; M0 is the magnitude of the earthquake in the earthquake statistical area; ΔM is the interval between each magnitude level, which is set to 0.5; β is the GR relationship coefficient of the earthquake statistical area, which represents the quantitative relationship between the earthquake level and the number of occurrences in the statistical area, M UA is the maximum magnitude of the earthquake in the earthquake statistical area, M i is the i-th magnitude earthquake in the earthquake statistical area.

4. The method for evaluating the resilience of power grids according to the functional requirements of urban systems under earthquake disasters according to claim 2 is characterized in that: The number and spatial distribution of scattered points in the earthquake statistical area are used to determine M i The probability of an earthquake of this magnitude occurring in each potential source area is expressed as follows: Among them, P occur ((x,y)|M i ) j Indicates M i The probability of an earthquake of this magnitude occurring in the jth potential source area; N j is the number of scattered points in the jth potential earthquake source area, N k is the number of scattered points in the kth potential earthquake source area, M Uj is the maximum magnitude of the jth potential earthquake source area, M Uk is the maximum magnitude of the kth potential earthquake source area, μ j is a Boolean constant. When M i Located between M0 and M Uj When between, take 1, M i Greater than M Uj When 0.

5. The method for evaluating the resilience of power grids according to the functional requirements of urban systems under earthquake disasters according to claim 1 is characterized in that: The method of obtaining the peak acceleration of earthquake motion at different epicenter distances by adopting the earthquake attenuation ellipse model and then constructing the failure probability model of the surface components and the buried pipeline under the earthquake scene includes the following steps: The earthquake magnitude is segmented to construct the attenuation of earthquake motion parameters in different magnitude ranges, and the peak acceleration of earthquake motion is determined based on the magnitude and epicenter distance of the earthquake; The failure probability of surface components is described by adopting a fragility model; Since the probability of buried pipeline failure is affected by factors such as geology, pipe diameter, seismic intensity and pipeline length, the buried pipeline failure probability model is obtained by combining the simplified model of pipeline segment seismic damage rate with the seismic motion parameters and seismic intensity conversion formula. Its expression is as follows: P pipe =1-exp(-R f ·L) Among them, R f is the seismic damage rate of underground pipeline sections; C d is the underground pipeline diameter coefficient; C g is the geological coefficient; P pipe is the probability of serious damage to the buried pipeline, and L is the length of the buried pipeline.

6. The method for evaluating the resilience of power grids according to the functional requirements of urban systems under earthquake disasters according to claim 5 is characterized in that: The failure probability of the surface components is described by adopting the fragility model, and its expression is as follows: in, For k element in Y PGA The probability of being in the jth damage state under the peak acceleration of the earthquake motion; represents the sequence number of the four damage states, j=1~4 represents slight damage, moderate damage, severe damage and complete damage respectively; They are the median and standard deviation of the fragility curves of the four damage states.

7. The method for evaluating the resilience of power grids according to the functional requirements of urban systems under earthquake disasters according to claim 1 is characterized in that: The urban water supply network model comprises a node head constraint model, a water pipe flow model, a water pump operation state model and a water pump and power grid energy coupling relationship model.

8. The method for evaluating the resilience of power grids according to the functional requirements of urban systems under earthquake disasters according to claim 1 is characterized in that: The city gas supply network model includes a node gas pressure constraint model, a gas supply network flow model, a compressor operation state model, a compressor energy coupling model and a gas turbine energy coupling model.

9. The method for evaluating the resilience of power grids according to the functional requirements of urban systems under earthquake disasters according to claim 1, characterized in that: The construction of a power grid resilience recovery model based on the objective function, decision variables and condition constraint library under earthquake disasters and taking into account the functional requirements of the urban lifeline system based on distribution network reconstruction and island division includes the following steps: In the earthquake disaster scenario, according to the demand of each user for electricity, water and gas resources, the functional loss of the entire city lifeline system in the earthquake scenario can be reduced. The expression is as follows: Among them, α i +β i +γ i =1, ω i is the importance weight of user i; α i , β i , γ i are the demand ratio parameters for electricity resources, water resources, and gas resources in the energy structure of user i, respectively. For the same user i, α i , β i , γ i The sum is 1; are the amount of electricity, water and gas resources restored by user i in period t under the disaster scenario; are the electricity, water and gas resource demands of user i in period t under normal circumstances; Ω is the set of all users; The main grid and the distribution grid exchange electric power through the interconnection line. When the main grid transmits power to the distribution grid, it takes positive value, otherwise it takes negative value. Construct the main distribution network power interaction constraint model, and its expression is as follows: in, are respectively the active and reactive power transmitted by the tie line received by node i in the distribution network at time t; are the upper limits of active and reactive power transmitted by the tie line received by node i in the distribution network at time t, respectively; are the lower limits of active and reactive power transmitted by the tie line received by node i in the distribution network at time t, respectively; and They are respectively the active and reactive power of the load on the main grid node j at time t; and are the power transmitted from the main grid to the distribution grid through the tie line; and They are respectively the active and reactive power generated by the main grid power supply node; and are the active and reactive power cut at the main grid node j at time t respectively; based on the binary variables of the power transmitted between nodes, the square value of the current amplitude transmitted between nodes, the square value of the voltage amplitude between nodes, the impedance of the line between nodes and the connectivity state between nodes, the distribution network operation model is constructed; Construct voltage safety operation constraints and current safety operation constraints; Construct radial constraints on distribution networks; Based on the binary variables of the transmission power between nodes, the square value of the transmission current amplitude between nodes, the square value of the voltage amplitude between nodes, the impedance of the line between nodes and the connectivity state between nodes, the distribution network operation model is constructed, and its expression is as follows: in, is the active power transmitted from node i to node j at time t; is the active power demand of residents at node i at time t; is the proportion of active power recovery of residents at node i at time t; r ki is the resistance value of the line between node k and node i; is the reactive power transmitted from node i to node j at time t; is the reactive power demand of residents at node i at time t; ki is the reactance value of the line between node k and node i; is the square value of the current amplitude transmitted from node k to node i at time t; is the square of the voltage amplitude at node i at time t; is a binary variable indicating the connectivity status between node i and node j at a given moment. The value is 1 if there is connectivity and 0 if there is none. M is a sufficiently large positive number.

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