A simulation method for simulating the state of cascading failures in the power grid under the action of typhoon disasters

Abstract

The present invention discloses a simulation method for simulating the cascading failure state of a power grid under the action of typhoon disasters. First, a circulation wind field model and a moving wind field model of a typhoon are established according to a typhoon data set, and then a typhoon spatio-temporal distribution model is established. Next, a vulnerability curve of power grid components is drawn to obtain the damage probability of power grid components corresponding to different wind speeds. Then, the set of working states of power grid components is abstracted into Markov states, and a state transition model of the power system is constructed to generate a set of faulty power grid components at different times under the action of a typhoon. The present invention takes into account the spatio-temporal characteristics of typhoon disasters, combines the vulnerability analysis of power grid components, and gives a power grid fault sampling simulation method, which can realize the real-time prediction of the fault states of each component and sub-region of the power grid, accurately simulate the impact of extreme typhoons on the power grid, and provide an effective reference basis for the normal operation and immediate maintenance of the power grid during disasters, and is suitable for being widely promoted and used.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid operation, and particularly relates to a simulation method for simulating the cascading fault state of a power grid under the action of typhoon disasters. Background Art

[0002] In recent years, due to global climate change, extreme disasters such as typhoons have occurred frequently. High-intensity typhoons have damaged the equipment of the power system, posing a great challenge to the safe and stable operation of the power system. In 2019, Typhoon Lekima landed in Zhejiang. When it landed, it was at the super typhoon level, causing damage to power facilities in many places. 72 substations above 35 kV and 3,753 lines above 10 kV in Zhejiang, Fujian, Shanghai and other places were damaged, and 5.5355 million customers were without power.

[0003] The power grid is a complex network with multiple nodes and branches. A complete power network includes a transmission network with a ring network and a distribution network with a radial structure, including large centralized power plants, substations and loads. Under the action of typhoon disasters, the nodes (power generation nodes, intermediate nodes and load nodes) and branches of the network may be damaged, resulting in the outage of some areas of the power grid.

[0004] It can be seen that although typhoons are low-probability events, the losses caused to the power grid are huge, and the cost invested in the later maintenance stage is high. Since most power equipment is located outdoors, it is easy to be damaged such as broken and fallen under the action of typhoons, and the strong precipitation and landslides caused by typhoons will also affect the power grid facilities. 1. Although the meteorological department can make accurate early warnings before the typhoon lands, the power department usually lacks a reasonable assessment of the harmfulness of typhoons and cannot deeply study the impact degree and scope of typhoon disasters on the power grid, resulting in great difficulties in formulating safety defense measures; 2. In order to cope with such low-probability - high-loss extreme events, it is necessary to simulate the occurrence and development process of power grid faults under disasters, so as to evaluate the resilience level of the power grid and formulate measures to improve the resilience of the power system; Therefore, it is necessary to design a simulation method for simulating the cascading fault state of a power grid under the action of typhoon disasters. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art. In order to better and effectively solve the problem of simulating the cascading faults of the power grid with the spatio-temporal characteristics of typhoon disasters, a simulation method for simulating the cascading fault state of a power grid under the action of typhoon disasters is provided, which has the advantages of being able to predict the power grid fault state in real time, finally forming a time-domain model of the power grid state, and providing a reference for the repair plan in the power grid repair stage.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A simulation method for simulating the cascading fault state of a power grid under the action of typhoon disasters, including the following steps:

[0008] Step (A): Establish a typhoon circulation wind field model and a moving wind field model based on the typhoon data set, and then establish a typhoon spatio-temporal distribution model;

[0009] Step (B): Draw the vulnerability curves of power grid components to obtain the damage probabilities of power grid components corresponding to different wind speeds;

[0010] Step (C): Abstract the working state set of power grid components into Markov states and construct a state transition model of the power system to generate a set of faulty power grid components at different times under the action of typhoons;

[0011] Step (D): Use the state transition model and generate a set of power grid component faults according to the typhoon spatio-temporal distribution model and the vulnerability curves of power grid components, and then deduce the evolution of cascading faults according to the line overload situation, and finally generate a power grid component fault state matrix to complete the simulation operation.

[0012] For the foregoing simulation method for simulating the cascading fault state of a power grid under the action of typhoon disasters, in step (A), a typhoon circulation wind field model and a moving wind field model are established based on the typhoon data set, and then a typhoon spatio-temporal distribution model is established. The typhoon spatio-temporal distribution model includes a typhoon wind field space model and a time-domain distribution model of the maximum typhoon wind speed. The specific steps are as follows:

[0013] Step (A1): Construct a typhoon circulation wind field model. The typhoon circulation wind field is a circular symmetric wind field generated by the pressure gradient. The typhoon wind speed is the lowest at the position of the typhoon eye. Taking the typhoon eye as the center, as the distance from the typhoon eye gradually increases, the wind speed first increases and then decreases, and reaches the highest at the position of the maximum wind speed radius. The Batts model is used to simulate the distribution of the typhoon circulation wind field as shown in formula (1):

[0014]

[0015] where r is the distance from the typhoon eye, v is the wind speed at a position r away from the typhoon eye, is the maximum typhoon wind speed, and R max is the maximum wind speed radius of the typhoon;

[0016] Step (A2): Construct a typhoon moving wind field model. The moving wind field is a wind field generated by the movement of the typhoon. In order to simulate the asymmetry of the typhoon wind field, the vector synthesis of the circulation wind field and the moving wind field is adopted. The specific steps are as follows:

[0017] Step (A21): Use the Miyazaki Masae model to simulate the distribution of the typhoon moving wind field as shown in formula (2):

[0018]

[0019] Among them, r is the distance from the typhoon eye, and v x is the eastward component of the moving speed, and v y is the northward component of the moving speed;

[0020] Step (A22), the eastward component and the northward component of the typhoon moving speed can be calculated through the longitude and latitude information of the typhoon, as shown in Formulas (3) and (4).

[0021]

[0022]

[0023] Among them, θ t and are the longitude and latitude of the typhoon at time t, and θ t+△t and are the longitude and latitude of the typhoon at time t + △t;

[0024] Step (A3), construct a typhoon wind field model under the superposition of the circulation wind field and the moving wind field, and add the vectors of Formula (1) and Formula (3), as shown in Formula (5).

[0025]

[0026] Among them, α is the angle between the line connecting the wind speed calculation point and the typhoon eye and the due east direction, and c 1 and c 2 are used to correct the wind field model;

[0027] Step (A4), obtain the time-domain distribution model of the typhoon wind speed. In the Chinese historical typhoon database, search for relevant data based on the current typhoon occurrence month, with a search interval of one month before and after, to obtain typhoon samples that meet seasonal similarity, and then store the typhoon samples according to the time-domain - wind speed sequence, so as to obtain the time-domain distribution model of the maximum typhoon wind speed at the maximum wind speed radius R max of the typhoon.

[0028] The foregoing simulation method for simulating the cascading fault state of the power grid under the action of typhoon disasters, step (B), draw the vulnerability curve of the power grid components to obtain the damage probability of the power grid components corresponding to different wind speeds, where the power grid components include poles and towers and lines, calculate the vulnerability models of the poles and towers and the lines. Under the action of typhoon, the poles and towers and the lines will have a damage probability. The vulnerability curve is the damage probability under different intensities of external interference. Define the vulnerability curves of the poles and towers and the lines as shown in Formula (6).

[0029]

[0030] Among them, \(v\) is the wind speed borne by the line element, and \(V\) is the rated wind speed of the element during design.

[0031] The aforementioned simulation method for simulating the cascading fault state of the power grid under the action of typhoon disasters, step (C), abstracts the working state set of the power grid elements into Markov states and constructs a state transition model of the power system to generate the set of faulty power grid elements at different times under the action of typhoon. The specific steps are as follows.

[0032] Step (C1), obtain the state transition model of the system. During the typhoon disaster process, define the set of the working states of all elements as Markov states. The states of different elements are considered independent events, and the repair problem is not considered during the disaster process. Therefore, it is defined that the set of possibly faulty elements in two adjacent time intervals satisfies as shown in formula (7).

[0033]

[0034] Among them, \(\Omega\) C,t is the set of faulty elements at time \(t\), and \(\Omega\) C,t+1 is the set of faulty elements at time \(t + 1\);

[0035] Step (C2), the transition probability between two adjacent Markov states can be expressed as the product of the probabilities that the states of all power grid elements at time \(t\) are successfully transferred to time \(t + 1\), as shown in formula (8).

[0036]

[0037] Among them, \(S\) i,t represents the Markov state of the system at time \(t\), \(S\) i′,t+1 represents the Markov state of the system at time \(t + 1\), \(\Omega\) S,t is the set of Markov states of the system at time \(t\), \(s\) k,t is the state of the \(k\)th element at time \(t\), \(s\) k,t+1 represents the state of the \(k\)th element at time \(t + 1\), \(Pr(S\) i,t , \(S\) i′,t+1 ) represents the probability that the power system transfers from the \(S\) i,t state to the \(S\) i′,t+1 state, and \(Pr(s\) k,t , \(s\) k,t+1 ) represents the probability that the \(k\)th element transfers from the \(s\) k,t state to the \(s\) k,t+1 state;

[0038] Step (C3), \(Pr(s\) k,t , \(s\) k,t+1 ) can be calculated by formula (9).

[0039]

[0040] Among them, p k,t+1 represents the failure probability of the k-component at time t + 1. Assume that the working state of the power grid component is divided into 0 and 1, where 0 represents that the power grid component cannot work properly, and 1 represents that the power grid component works normally.

[0041] The aforementioned simulation method for simulating the cascading failure state of the power grid under the action of typhoon disasters, step (D), uses the state transition model and generates a power grid component failure set according to the typhoon spatio-temporal distribution model and the power grid component vulnerability curve, and then deduces the evolution of the cascading failure according to the line overload situation, and finally generates a power grid component failure state matrix to complete the simulation operation. The specific steps are as follows.

[0042] Step (D1), use the state transition model and generate a power grid component failure set according to the typhoon spatio-temporal distribution model and the power grid component vulnerability curve. Conduct Monte Carlo simulation on the power system to generate failure scenarios, update the wind field model of the typhoon at the current moment, and then calculate its failure probability according to the typhoon wind field distribution and the vulnerability models of the line and the tower. Generate a uniformly distributed random number between 0 and 1. If the generated random number is less than its failure probability, it is considered that the power grid component is damaged, and a power grid component failure set is generated.

[0043] Step (D2), deduce the evolution of the cascading failure according to the line overload situation, and finally generate a power grid component failure state matrix. Among them, deducing the evolution of the cascading failure according to the line overload situation includes calculating the working state of the transmission line, calculating the working state of the transmission line, detecting the subnets in the power grid, calculating the power flow distribution of the power grid through the DC power flow model, ending the cascading process, and updating the time. The specific steps are as follows.

[0044] Step (D21), calculate the working state of the transmission line. The transmission line is composed of towers and lines in series. When calculating whether the whole line can work properly, it can be calculated as the product of the working states of all power grid components on the series line. If the transmission channel fails due to a tower or line fault and cannot work properly, it is cut off.

[0045] Step (D22), detect the subnets in the power grid. If there is no power plant node in the subnet, the subnet loses all load nodes; if the power generation in the subnet is greater than the load, adjust the generator output according to formula (11); if the load in the subnet is greater than the power generation, cut off the load uniformly according to formula (12).

[0046]

[0047]

[0048] Among them, i represents the power plant nodes that can still generate power after the wind disaster, j represents the load nodes that can still work normally after the wind disaster, and P Gi represents the power generation of the i-th power plant node in the subnet at the current moment, and P' Gi represents the power generation of the i-th power plant node in the subnet before the wind disaster, and P Lj represents the load of the j-th load node in the subnet at the current moment, and P' Lj represents the load of the j-th load node in the subnet before the wind disaster;

[0049] Step (D23), calculate the power flow distribution of the power grid through the DC power flow model. If the branch power flow exceeds the rated capacity of the line, cut it off and go to step (C22). If no line is cut off, go to step (C24). The branch power flow equation is shown in formula (10),

[0050]

[0051] Among them, F is the branch power flow, defined as M f is the admittance matrix associated with the branch-node, is M f the matrix obtained by deleting the columns related to the reference node, and B 0 is the branch admittance the n×n matrix constructed, is B 0 the corresponding fixed admittance matrix;

[0052] Step (D24), the cascading process ends, generating the fault set of the transmission channel at the current moment and the fault set of the power grid components;

[0053] Step (D25), update the time, linearly interpolate the wind speed and the typhoon longitude and latitude between two sampling points. To evaluate the maximum damage degree of the system, take the larger value of the wind speed and the maximum wind speed radius among the adjacent sampling points, and return to step (D1) until the typhoon ends, generating the time-series power grid component fault status matrix.

[0054] The beneficial effects of the present invention are:

[0055] (1) The present invention considers the spatio-temporal characteristics of typhoon disasters, combines the vulnerability analysis of power grid components, and gives a power grid fault sampling simulation method, which can realize the real-time prediction of the fault states of various components and partitions of the power grid, and accurately simulate the impact of extreme typhoons on the power grid, providing an effective reference basis for the normal operation and immediate maintenance of the power grid during disasters.

[0056] (2) The present invention establishes a power grid cascading failure model under the action of extreme typhoon disasters, develops a time-domain simulation method for fault states, can effectively deduce the failure process of the power grid under extreme typhoon weather, can also sample the fault states of power grid components in chronological order, and can evaluate the damage degree of the power grid in real time, providing a basis for power grid resilience calculation and formulating an optimal repair plan. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is the overall flowchart of the present invention;

[0058] Figure 2 is the curve distribution diagram of the typhoon circulation wind field of the present invention;

[0059] Figure 3 is the curve distribution diagram of the typhoon moving wind field of the present invention;

[0060] Figure 4 is the wind speed distribution diagram of Typhoon Lekima of the present invention;

[0061] Figure 5 is the vulnerability curve diagram of the power grid components of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0062] The present invention will be further described below in conjunction with the accompanying drawings of the specification.

[0063] As Figures 1-5 shown, a simulation method for simulating the cascading fault state of a power grid under the action of typhoon disasters of the present invention includes the following steps

[0064] Step (A), establish a typhoon circulation wind field model and a moving wind field model of the typhoon according to the typhoon data set, and then establish a typhoon spatio-temporal distribution model, wherein the typhoon spatio-temporal distribution model includes a typhoon wind field space model and a typhoon maximum wind speed time-domain distribution model. The specific steps are as follows

[0065] Among them, due to the nature of natural disasters changing with time and space, the failure probability of network components changes with time and disaster intensity, which means that the power grid cascading failure model is a dynamic time-domain model;

[0066] Step (A1), construct a typhoon circulation wind field model. The typhoon circulation wind field is a circular symmetric wind field generated by the pressure gradient. The typhoon wind speed is the lowest at the position of the typhoon eye. Taking the typhoon eye as the center, as it gradually moves away from the typhoon eye, the wind speed first increases and then decreases, and reaches the highest at the position of the maximum wind speed radius. The Batts model is used to simulate the distribution of the typhoon circulation wind field as shown in formula (1)

[0067]

[0068] Among them, r is the distance from the typhoon eye, and v is the wind speed at a position r away from the typhoon eye. is the maximum wind speed of the typhoon, and R max is the radius of the maximum wind speed of the typhoon;

[0069] Step (A2): Construct a moving wind field model of the typhoon. The moving wind field is the wind field generated by the movement of the typhoon. In order to simulate the asymmetry of the typhoon wind field, the vector synthesis of the circulation wind field and the moving wind field is adopted. The specific steps are as follows.

[0070] Step (A21): Use the Miyazaki Masae model to simulate the distribution of the moving wind field of the typhoon as shown in formula (2).

[0071]

[0072] Among them, r is the distance from the typhoon eye, and v x is the eastward component of the moving speed, and v y is the northward component of the moving speed;

[0073] Step (A22): The eastward component and northward component of the typhoon moving speed can be calculated through the longitude and latitude information of the typhoon, as shown in formula (3) and formula (4).

[0074]

[0075]

[0076] Among them, θ t and are the longitude and latitude of the typhoon at time t, and θ t+△t and are the longitude and latitude of the typhoon at time t + △t;

[0077] Step (A3): Construct a typhoon wind field model under the superposition of the circulation wind field and the moving wind field. Vectorially add formula (1) and formula (3), as shown in formula (5).

[0078]

[0079] Among them, α is the angle between the line connecting the wind speed calculation point and the typhoon eye and the due east direction, and c 1 and c 2 are used to correct the wind field model;

[0080] Step (A4): Obtain the time-domain distribution model of the typhoon wind speed. In the Chinese historical typhoon database, search for relevant data based on the current typhoon occurrence month, with a search interval of one month before and after, to obtain typhoon samples that meet seasonal similarity. Then store the typhoon samples according to the time-domain - wind speed sequence, and the radius of the maximum wind speed R can be obtained.max The time-domain distribution model of the maximum typhoon wind speed at

[0081] Step (B): Draw the vulnerability curves of grid components to obtain the damage probabilities of grid components corresponding to different wind speeds. The grid components include poles and towers and lines. Calculate the vulnerability models of poles and towers and lines. Under the action of a typhoon, there will be damage probabilities for poles and towers and lines. The vulnerability curve is the damage probability under different intensities of external interference. Define the vulnerability curves of poles and towers and lines as shown in formula (6).

[0082]

[0083] where v is the wind speed borne by the line component, and V is the rated wind speed of the component during design.

[0084] Step (C): Abstract the set of working states of grid components into Markov states and construct a state transition model of the power system to generate the set of faulty grid components at different times under the action of a typhoon. The specific steps are as follows.

[0085] Step (C1): Obtain the state transition model of the system. During the typhoon disaster process, define the set of working states of all components as Markov states. The states of different components are considered independent events, and the repair problem is not considered during the disaster process. Therefore, define that the set of possible faulty components in two adjacent time intervals satisfies as shown in formula (7).

[0086]

[0087] where Ω C,t is the set of faulty components at time t, and Ω C,t+1 is the set of faulty components at time t + 1;

[0088] Step (C2): The transition probability between two adjacent Markov states can be expressed as the product of the probabilities that the states of all grid components at time t successfully transfer to time t + 1, as shown in formula (8).

[0089]

[0090] where S i,t represents the Markov state of the system at time t, S i′,t+1 represents the Markov state of the system at time t + 1, Ω S,t is the set of Markov states of the system at time t, s k,t is the state of component k at time t, s k,t+1 represents the state of component k at time t + 1, and Pr(S i,t , S i′,t+1 ) represents the probability that the power system transfers from S i,tThe state transfers to S i′,t+1 The probability of the state, Pr(s k,t , s k,t+1 ) represents the probability that the k-component transfers from the s k,t state to the s k,t+1 state;

[0091] Step (C3), Pr(s k,t , s k,t+1 ) can be calculated by formula (9),

[0092]

[0093] where p k,t+1 represents the failure probability of the k-component at time t + 1. Assume that the working states of power grid components are divided into 0 and 1, where 0 represents that the power grid component cannot work properly, and 1 represents that the power grid component works properly.

[0094] Step (D), Use the state transition model and generate the power grid component fault set according to the typhoon spatio-temporal distribution model and the power grid component vulnerability curve, then deduce the evolution of cascading faults according to the line overload situation, and finally generate the power grid component fault state matrix to complete the simulation operation. The specific steps are as follows:

[0095] Step (D1), Use the state transition model and generate the power grid component fault set according to the typhoon spatio-temporal distribution model and the power grid component vulnerability curve, conduct Monte Carlo simulation on the power system to generate fault scenarios, update the wind field model of the typhoon at the current moment, and then calculate its damage probability according to the typhoon wind field distribution and the vulnerability models of lines and towers, generate a uniformly distributed random number of 0 - 1. If the generated random number is less than its damage probability, it is considered that the power grid component is damaged, and a power grid component fault set is generated;

[0096] Step (D2), Deduce the evolution of cascading faults according to the line overload situation, and finally generate the power grid component fault state matrix. Among them, deducing the evolution of cascading faults according to the line overload situation includes calculating the working state of transmission lines, calculating the working state of transmission lines, detecting subnets in the power grid, calculating the power flow distribution of the power grid through the DC power flow model, ending the cascading process, and updating the time. The specific steps are as follows:

[0097] Step (D21), Calculate the working state of the transmission line. The transmission line is composed of towers and lines in series. When calculating whether the whole line can work properly, it can be calculated as the product of the working states of all power grid components on the series line. If the transmission channel fails due to tower or line faults and cannot work properly, it is cut off;

[0098] Step (D22): Detect the subnets in the power grid. If there is no power plant node in a subnet, then all load nodes in that subnet are lost. If the power generation in the subnet is greater than the load, adjust the generator output according to formula (11). If the load in the subnet is greater than the power generation, cut off the load uniformly according to formula (12).

[0099]

[0100]

[0101] Among them, i represents the power plant nodes that can still generate power after the wind disaster, j represents the load nodes that can still work normally after the wind disaster, and P Gi represents the power generation of the i-th power plant node in the subnet at the current moment, and P' Gi represents the power generation of the i-th power plant node in the subnet before the wind disaster, and P Lj represents the load of the j-th load node in the subnet at the current moment, and P' Lj represents the load of the j-th load node in the subnet before the wind disaster;

[0102] Step (D23): Calculate the power flow distribution of the power grid through the DC power flow model. If the branch power flow exceeds the rated capacity of the line, cut it off and go to step (C22). If no line is cut off, go to step (C24). The branch power flow equation is as shown in formula (10).

[0103]

[0104] Among them, F is the branch power flow, defined as M f is the admittance matrix associated with the branch-node, is M f the matrix obtained by deleting the columns related to the reference node, and B 0 is the branch admittance the constructed n×n matrix, is B 0 the corresponding fixed admittance matrix;

[0105] Step (D24): The cascading process ends, generating the fault set of the transmission channels at the current moment and the fault set of the power grid components;

[0106] Step (D25): Update the time. Linearly interpolate the wind speed and the typhoon longitude and latitude between two sampling points. To evaluate the maximum damage degree of the system, take the larger value of the wind speed and the maximum wind speed radius among the adjacent sampling points, and return to step (D1) until the typhoon ends, generating the time-series power grid component fault status matrix.

[0107] To further elaborate on the usage effect of the present invention, a specific embodiment of the present invention is introduced below.

[0108] To describe the maximum damage situation of the power system under the action of a typhoon, the time-domain distribution data of the wind speed of the "Lekima" typhoon, which has the strongest comprehensive wind and rain intensity in the past 60 years, is selected as Figure 4 shown; setting the rated wind speed of the overhead line to 30 m / s and the rated wind speed of the tower to 50 m / s, the vulnerability curve of the power grid components is as Figure 5 shown.

[0109] In summary, a simulation method for simulating the cascading failure state of a power grid under the action of a typhoon disaster according to the present invention first establishes a typhoon model, which helps to simulate a real typhoon scenario, then applies the typhoon data in reality to the simulation model to provide a basis for modeling the subsequent power grid failure state. Then, a vulnerability curve of the power grid components is proposed and used to describe the corresponding relationship between the failure probability of power grid components such as towers and lines and the wind speed. Then, the wind speed model and the vulnerability curve are integrated to obtain the component failure rate at different times. Subsequently, the Markov Monte Carlo method is used for failure state sampling to obtain the set of failure states at each moment under the action of the typhoon, which helps the power department accurately evaluate the hazards of the typhoon and improve the response ability to typhoon disasters.

[0110] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A simulation method for simulating the cascading fault state of a power grid under the action of typhoon disasters, characterized in that: It includes the following steps, Step (A), establish a circulation wind field model and a moving wind field model of the typhoon according to the typhoon data set, and then establish a typhoon spatio-temporal distribution model; Step (B), draw the vulnerability curve of power grid components to obtain the damage probability of power grid components corresponding to different wind speeds; Step (C), abstract the working state set of power grid components into Markov states, and construct a state transition model of the power system to generate a set of faulty power grid components at different times under the action of the typhoon; Step (D), use the state transition model and generate a set of power grid component faults according to the typhoon spatio-temporal distribution model and the power grid component vulnerability curve, and then deduce the evolution of cascading faults according to the line overload situation, and finally generate a power grid component fault state matrix to complete the simulation operation. The specific steps are as follows, Step (D1), use the state transition model and generate a set of power grid component faults according to the typhoon spatio-temporal distribution model and the power grid component vulnerability curve, perform Monte Carlo simulation on the power system to generate a fault scenario, update the wind field model of the typhoon at the current moment, and then calculate its damage probability according to the typhoon wind field distribution and the vulnerability models of the line and the tower, generate a uniformly distributed random number between 0 and 1, if the generated random number is less than its damage probability, it is considered that the power grid component is damaged, and a set of power grid component faults is generated; Step (D2), deduce the evolution of cascading faults according to the line overload situation, and finally generate a power grid component fault state matrix, where deducing the evolution of cascading faults according to the line overload situation includes calculating the working state of the transmission line, calculating the working state of the transmission line, detecting the subnets in the power grid, calculating the power flow distribution of the power grid through the DC power flow model, ending the cascading process and updating the time. The specific steps are as follows, Step (D21), calculate the working state of the transmission line. The transmission line is composed of towers and lines in series. When calculating whether the whole line can work normally, it can be calculated as the product of the working states of all power grid components on the series line. If the transmission line has a tower or line fault that causes it to not work normally, it is cut off; Step (D22), detect the subnets in the power grid. If there is no power plant node in the subnet, the subnet loses all load nodes; if the power generation in the subnet is greater than the load, adjust the generator output according to formula (11); if the load in the subnet is greater than the power generation, cut off the load uniformly according to formula (12); Among them, i represents the power plant nodes that can still generate power after the wind disaster, and j represents the load nodes that can still work normally after the wind disaster. P Gi represents the power generation of the i-th power plant node in the subnet at the current moment. P G ' i represents the power generation of the i-th power plant node in the subnet before the wind disaster. P Lj represents the load of the j-th load node in the subnet at the current moment. P L ' j represents the load of the j-th load node in the subnet before the wind disaster; Step (D23), calculate the power flow distribution of the power grid through the DC power flow model. If the branch power flow exceeds the rated capacity of the line, cut it off and go to step (C22). If no line is cut off, go to step (C24). The branch power flow equation is shown in formula (10); Among them, F is the branch power flow, defined as M f is the admittance matrix associated with the branch-node, is the matrix obtained by deleting the columns related to the reference node from M f , B 0 is the branch admittance to construct an n×n matrix, is the fixed admittance matrix corresponding to B 0 ; Step (D24), the cascading process ends, generating a set of faults of the current transmission channel and a set of power grid component faults; Step (D25), update the time. Perform linear interpolation on the wind speed and the typhoon's longitude and latitude between two sampling points. To evaluate the maximum damage degree of the system, take the larger values of the wind speed and the maximum wind speed radius among adjacent sampling points. Return to step (D1) until the typhoon ends, and generate a time-series matrix of the fault states of power grid components.

2. A simulation method for simulating the cascading fault states of a power grid under typhoon disasters according to claim 1, characterized in that: Step (A), establish a typhoon circulation wind field model and a moving wind field model of the typhoon based on the typhoon data set, and then establish a typhoon spatio-temporal distribution model. The typhoon spatio-temporal distribution model includes a typhoon wind field spatial model and a typhoon maximum wind speed time-domain distribution model. The specific steps are as follows. Step (A1), construct a typhoon circulation wind field model. The typhoon circulation wind field is a circular symmetric wind field generated by the pressure gradient. The typhoon wind speed is the lowest at the position of the typhoon eye. Taking the typhoon eye as the center, as the distance from the typhoon eye gradually increases, the wind speed first increases and then decreases, and reaches the highest at the position of the maximum wind speed radius. Use the Batts model to simulate the distribution of the typhoon circulation wind field as shown in formula (1). Among them, r is the distance from the typhoon eye, and v is the wind speed at a position r away from the typhoon eye. is the maximum wind speed of the typhoon, and R max is the radius of the maximum wind speed of the typhoon. Step (A2), construct a typhoon moving wind field model. The moving wind field is the wind field generated by the movement of the typhoon. In order to simulate the asymmetry of the typhoon wind field, the vector synthesis method of the circulation wind field and the moving wind field is adopted. The specific steps are as follows. Step (A21), use the Miyazaki Masae model to simulate the distribution of the typhoon moving wind field as shown in formula (2). where r is the distance from the typhoon eye, v x is the due east component of the moving speed, v y is the due north component of the moving speed; Step (A22), the eastward component and the northward component of the typhoon moving speed can be calculated through the longitude and latitude information of the typhoon, as shown in formula (3) and formula (4). where, θ t and are the longitude and latitude of the typhoon at time t, and θ t+△t and are the longitude and latitude of the typhoon at time t + △t; Step (A3), construct a typhoon wind field model under the superposition of the circulation wind field and the moving wind field, and add the vectors of formula (1) and formula (3) as shown in formula (5). where α is the angle between the line connecting the wind speed calculation point and the typhoon eye and the due east direction, c 1 and c 2 are used to correct the wind field model; Step (A4): Obtain the time-domain distribution model of the typhoon's wind speed. In the Chinese historical typhoon database, search for relevant data based on the current typhoon occurrence month, with a search interval of one month before and after, to obtain typhoon samples that meet seasonal similarity. Then store the typhoon samples according to the time-domain - wind speed sequence to obtain the time-domain distribution model of the maximum wind speed radius R max of the typhoon at the location.

3. A simulation method for simulating the cascading fault states of a power grid under typhoon disasters according to claim 2, characterized in that: Step (B), draw the vulnerability curves of power grid components to obtain the damage probabilities of power grid components corresponding to different wind speeds. The power grid components include poles and lines. Calculate the vulnerability models of poles and lines. Under the action of a typhoon, there will be damage probabilities for poles and lines. The vulnerability curve is the damage probability under different intensities of external interference. Define the vulnerability curves of poles and lines as shown in formula (6). Where, v is the wind speed borne by the line component, and V is the rated wind speed of the component during design.

4. A simulation method for simulating the cascading fault states of a power grid under typhoon disasters according to claim 3, characterized in that: Step (C), abstract the working state set of power grid components into Markov states, and construct a state transition model of the power system to generate a set of fault power grid components at different times under the action of a typhoon. The specific steps are as follows. Step (C1): Obtain the state transition model of the system. During the typhoon disaster process, the set of working states of all components is defined as Markov states. The states of different components are considered independent events, and the repair problem is not considered during the disaster process. Therefore, it is defined that the set of components that may fail in two adjacent time intervals satisfies the formula (7) as follows: Among them, Ω C,t is the set of faulty components at time t, and Ω C,t+1 is the set of faulty components at time t + 1; Step (C2): The transition probability between two adjacent Markov states can be expressed as the product of the probabilities that the states of all power grid components at time t successfully transfer to time t + 1, as shown in formula (8): Among them, S i,t represents the Markov state of the system at time t, and S i′,t+1 represents the Markov state of the system at time t + 1. Ω S,t is the set of Markov states of the system at time t, and s k,t is the state of component k at time t, and s k,t+1 represents the state of component k at time t + 1. Pr(S i,t , S i′,t+1 ) represents the probability that the power system transfers from the S i,t state to the S i′,t+1 state, and Pr(s k,t , s k,t+1 ) represents the probability that component k transfers from the s k,t state to the s k,t+1 state; Step (C3), Pr(s k,t , s k,t+1 ) can be calculated by formula (9), Among them, p k,t+1 represents the failure probability of the k-component at time t + 1. Assume that the working state of the power grid component is divided into 0 and 1, where 0 represents that the power grid component cannot work properly, and 1 represents that the power grid component works normally.

Images