Typhoon disaster-oriented receiving-end power grid backbone grid frame searching method

Abstract

The invention relates to the technical field of disaster prevention and disaster resistance of a power system, in particular to a receiving-end power grid backbone grid frame searching method for typhoon disasters, which comprises the following steps of: simulating typhoon paths, evaluating fault probabilities of power transmission lines of a receiving-end power grid under different typhoon paths, comparing the fault probabilities of the lines with a preset threshold value, and calculating the fault probability of the power transmission lines of the receiving-end power grid. Forming a power transmission line fault set; the difference of disaster loss caused by cutting off different types of loads and scales thereof is considered, and a utility function is utilized to simulate the function relationship between the load shedding amount and the load shedding loss; and constructing a backbone grid frame search model by taking the minimum grid frame scale as an optimization target, and solving the model to obtain the backbone grid frame of the receiving-end power grid. According to the method, by simulating the fault probability of the typhoon path and the power transmission line, introducing the utility function, taking the minimum grid scale as an optimization target, constructing the backbone grid frame search model, and solving the model, the backbone grid frame of the receiving-end power grid is obtained, and the load supply guarantee capacity of the receiving-end power grid during the typhoon disaster period is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of disaster prevention and mitigation of electric power systems, and in particular to a method for searching a backbone grid of a receiving-end power grid facing typhoon disasters. Background Art

[0002] In recent years, extreme disasters represented by typhoons have occurred frequently, bringing severe challenges to the safe supply of power systems. my country has a long coastline, and most of its economically developed cities are located in the southeast coast. However, coastal cities are extremely vulnerable to typhoon disasters, and power supply interruptions will bring huge economic losses. Typhoon disaster factors include strong winds and rainfall, which can cause problems such as the collapse of transmission towers and the disconnection of wind turbines. This not only affects the power supply at the power supply end, but also causes transmission congestion, resulting in obstruction of power transmission. On the other hand, my country's resource endowment is unevenly distributed. Large energy bases are located in the west, while electricity loads are mostly located in coastal cities. A large number of ultra-high voltage AC and DC transmission lines extend from the west to the southeast coastal power consumption center, forming multiple large-scale receiving-end power grids. The receiving-end power grid itself has the characteristics of hollow power supply and weak support capacity. Coupled with the transmission congestion caused by extreme typhoon disasters and insufficient output of wind and solar energy, the receiving-end power grid under typhoon disasters is under tremendous pressure to ensure supply.

[0003] Therefore, there is an urgent need for a search method that can improve the ability to provide insurance during disasters while ensuring economic efficiency. Summary of the invention

[0004] In view of at least one of the above technical problems, the present invention provides a receiving power grid backbone network search method for typhoon disasters, which integrates natural disaster risk assessment and power system optimization to improve the load supply capability of the receiving power grid during typhoon disasters.

[0005] According to a first aspect of the present invention, a method for searching a receiving-end power grid backbone network for typhoon disasters is provided, comprising the following steps:

[0006] Simulate typhoon paths, evaluate the probability of transmission line failures at the receiving end power grid under different typhoon paths, compare the line failure probability with the preset threshold, and form a transmission line failure set;

[0007] Considering the differences in disaster losses caused by shedding different types of loads and their scales, the functional relationship between load shedding amount and load shedding loss is simulated using utility function.

[0008] Taking the minimum grid scale as the optimization goal, a backbone grid search model is constructed, and the backbone grid of the receiving-end power grid is obtained by solving the model.

[0009] In some embodiments of the present invention, the simulated typhoon path includes a set of fault scenarios of power transmission lines of the receiving power grid under the simulated typhoon path. The typhoon path is related to its landing location, landing angle, moving speed and direction, and its calculation formula is:

[0010]

[0011] In the formula, (x l ,y l ) represents the position of the typhoon center at landfall; α is the angle between the coastline and the typhoon's direction of travel assuming that the typhoon moves in a straight line; v0(t0) is the forward speed of the typhoon at time t0 assuming that the typhoon moves in a straight line.

[0012] In some embodiments of the present invention, in the transmission line fault set, the failure probability of the transmission line at a certain moment is expressed by the following formula:

[0013]

[0014] In the formula, v x,k (t0) represents the wind speed at the kth position of line x at time t0; v α represents the design wind speed of the line; μ and ν are coefficients; Δl represents the length of the line; P x,k (t0) is the failure probability of line x at time t0.

[0015] In some embodiments of the present invention, the failure probability of the transmission line at a certain moment also includes setting a line failure probability threshold For lines with a failure probability exceeding the threshold, Then the line is selected into the fault set Ω,

[0016]

[0017] In some embodiments of the present invention, the utility function represents the user's subjective willingness to bear the loss caused by load shedding.

[0018] In some embodiments of the present invention, the calculation formula for the load shedding amount and load shedding loss of the receiving-end power grid under a typhoon disaster is:

[0019]

[0020] In the formula, S loss Indicates load shedding loss; P ls Indicates load shedding; P set represents the threshold value of load shedding loss; e represents the natural logarithm.

[0021] In some embodiments of the present invention, the backbone grid is the minimum-scale grid that guarantees the power supply requirements of important users of the receiving power grid. With the minimum grid scale as the goal, combined with constraints such as avoiding high failure probability transmission channels and incorporating cables, a receiving power grid backbone grid search model is established.

[0022] In some embodiments of the present invention, the objective function minN is set B , N B Indicates the number of backbone network lines.

[0023] In some embodiments of the present invention, the constraints include:

[0024] Node power balance constraints:

[0025]

[0026] Line DC power flow constraints:

[0027]

[0028] Line capacity constraints:

[0029]

[0030] Power output constraints:

[0031]

[0032] Constraints on continuous reporting of loads at all levels:

[0033]

[0034] Where P i,t is the power output at node i at time t; Provide power for new energy power stations; l,t is the line flow; The first-level load, second-level load, and third-level load after load removal, ζ = 1, 2, 3; The load size of the first three levels of load shedding; b l is the line reactance; θ i,t and θ j,t is the voltage phase angle at both ends of the line; l It is a 0-1 variable of line status, where 1 means the line is running and 0 means the line is disconnected; is the line capacity; and Respectively represent the maximum and minimum output of the power supply.

[0035] In some embodiments of the present invention, the constraint condition further includes:

[0036] Constraints on the output range of new energy sources:

[0037]

[0038] Line operation status statistics constraints:

[0039]

[0040] Load utility constraints of each node:

[0041]

[0042] Eliminate high failure probability transmission lines:

[0043]

[0044] Cables to be included first:

[0045]

[0046] In the formula, Predict output for new energy power stations; S loss,i is the utility value of the lost load at node i; is the maximum utility value of the lost load of node i; Ω is the set of transmission circuit faults; W Ca A collection of cable lines.

[0047] The beneficial effects of the present invention are as follows: the present invention simulates the typhoon path and the failure probability of the transmission line, introduces the utility function, takes the minimum grid scale as the optimization goal, constructs a backbone grid search model, solves the model, and obtains the backbone grid of the receiving-end power grid; compared with the prior art, the load supply capacity of the receiving-end power grid during typhoon disasters is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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 recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 The present invention is a flowchart of the steps of a method for searching a receiving-end power grid backbone network for typhoon disasters in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0051] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0053] like Figure 1 The receiving-end power grid backbone network search method for typhoon disasters shown includes the following steps:

[0054] S10: simulate the typhoon path, evaluate the failure probability of the receiving power grid transmission line under different typhoon paths, compare the line failure probability with the preset threshold, and form a transmission line failure set;

[0055] S20: Considering the differences in disaster losses caused by shedding different types of loads and their scales, the utility function is used to simulate the functional relationship between load shedding amount and load shedding loss;

[0056] S30: Taking the minimum grid scale as the optimization goal, a backbone grid search model is constructed, and the backbone grid of the receiving-end power grid is obtained by solving the model.

[0057] In the above embodiment, the present invention introduces a utility function by simulating the typhoon path and the failure probability of the transmission line, takes the minimum grid scale as the optimization goal, constructs a backbone grid search model, solves the model, and obtains the backbone grid of the receiving-end power grid; compared with the prior art, the load supply capacity of the receiving-end power grid during typhoon disasters is improved.

[0058] In an embodiment of the present invention, the simulated typhoon path includes simulating a set of fault scenarios of power transmission lines of the receiving power grid under the typhoon path. The typhoon path is related to its landing location, landing angle, moving speed and direction, and its calculation formula is:

[0059]

[0060] In the formula, (x l ,y l) represents the position of the typhoon center at landfall; α is the angle between the coastline and the typhoon's direction of travel, assuming that the typhoon moves in a straight line; v0(t0) is the forward speed of the typhoon at time t0, assuming that the typhoon moves in a straight line. The landing location of the typhoon determines its direct impact range on the receiving power grid. Different landing locations may cause different areas in the receiving power grid to be affected. It is necessary to conduct scenario simulations for each possible landing location to assess the risk of transmission lines in different areas. The landing angle of the typhoon (i.e., the angle between the typhoon path and the coastline) has an important influence on the direction and intensity of the wind force. At a specific landing angle, the transmission line may show different failure probabilities due to different windward or leeward forces. The movement speed of the typhoon directly affects the duration of wind force and the cumulative pressure on the power grid facilities; when the movement speed is slow, the typhoon will affect a specific area for a longer time, which may lead to a higher risk of transmission line failure, while a fast-moving typhoon may expand the affected area. The movement direction of the typhoon determines the spatial distribution of its impact. Different movement directions may cause the transmission lines to be subjected to different wind pressures and impact forces, thus showing different fault characteristics. It is necessary to combine the geographical distribution and direction of the lines in the simulation to establish a set of transmission line fault scenarios. This component not only provides basic data for subsequent backbone grid optimization, but also helps power grid operators identify high-risk lines in advance.

[0061] In an embodiment of the present invention, in the transmission line fault set, the failure probability of the transmission line at a certain moment is expressed by the following formula:

[0062]

[0063] In the formula, v x,k (t0) represents the wind speed at the kth position of line x at time t0; v α represents the design wind speed of the line; μ and ν are coefficients; Δl represents the length of the line; P x,k (t0) is the failure probability of line x at time t0. By analyzing the failure probability of the line at different times and under different wind speed conditions, it is possible to identify high-risk transmission lines and their key locations.

[0064] In an embodiment of the present invention, the failure probability of a transmission line at a certain moment also includes setting a line failure probability threshold. For lines with a failure probability exceeding the threshold, Then the line is selected into the fault set Ω,

[0065]

[0066] The present invention combines complex typhoon scenarios with the risk quantification of power transmission lines, facilitating scientific analysis of the vulnerability of the power grid.

[0067] In an embodiment of the present invention, the utility function represents the user's subjective willingness to bear the loss caused by load shedding. It should be noted here that the subjective willingness to bear the loss refers to the user's subjective tolerance or acceptability of the loss caused by load shedding when the power supply is interrupted. It can be expressed as follows: for industrial users, power outages may cause production stagnation and huge losses, and the willingness to bear the loss is low; for ordinary residential users, short-term power outages may only bring inconvenience to life, and the willingness to bear the loss is relatively high. The setting of the utility function quantifies the sensitivity of different types of users to load shedding and provides a more accurate loss assessment.

[0068] In an embodiment of the present invention, the calculation formula for the load shedding amount and load shedding loss of the receiving-end power grid under a typhoon disaster is:

[0069]

[0070] In the formula, S loss Indicates load shedding loss; P ls Indicates load shedding; P set represents the threshold value of load shedding loss; e represents the natural logarithm. This formula refines the relationship between load shedding loss and load shedding amount into an adjustable dynamic model, which can truly reflect the changes in electricity demand and the differences in disaster-bearing willingness of different users under disasters.

[0071] In an embodiment of the present invention, the backbone grid is the minimum scale grid that guarantees the power supply requirements of important users of the receiving power grid. With the minimum grid scale as the goal, combined with avoiding high-failure probability transmission channels and incorporating cables and other constraints, a receiving-end power grid backbone grid search model is established. The backbone grid is the minimum scale network architecture in the receiving power grid that is streamlined and optimized to meet the power supply needs of important users. The minimum scale means that while minimizing resource input (such as the number and length of lines), it is ensured that electricity can be reliably delivered to important users. When optimizing the backbone grid, constraints need to be introduced to ensure that the model design meets actual needs. A high-failure probability transmission channel refers to a transmission line whose failure probability exceeds a threshold in a typhoon path simulation. Including low-risk channels such as cables means that cable lines are buried underground and are less affected by typhoons, and are considered to be more reliable transmission channels. The optimal backbone grid structure is automatically found based on the set goals (such as the minimum grid scale) and constraints through the backbone grid search model.

[0072] In an embodiment of the present invention, the objective function minN is set B , N BRepresents the number of backbone grid lines. Each transmission line involves construction, maintenance and operation costs. By reducing the number of lines, economic costs can be significantly reduced. For example, in an emergency situation in response to a typhoon disaster, reliable lines are given priority, and lines with a high probability of failure are removed from the grid, thereby optimizing resource allocation. This setting allows the backbone grid optimization results to be dynamically adjusted according to different disaster scenarios, providing a more flexible and efficient emergency response plan for the power grid.

[0073] In an embodiment of the present invention, the constraints include:

[0074] Node power balance constraints:

[0075]

[0076] Line DC power flow constraints:

[0077]

[0078] Line capacity constraints:

[0079]

[0080] Power output constraints:

[0081]

[0082] Constraints on continuous reporting of loads at all levels:

[0083]

[0084] Where P i,t is the power output at node i at time t; Provide power for new energy power stations; l,t is the line flow; The first-level load, second-level load, and third-level load after load removal, ζ = 1, 2, 3; The load size of the first three levels of load shedding; b l is the line reactance; θ i,t and θ j,t is the voltage phase angle at both ends of the line; z l It is a 0-1 variable of line status, where 1 means the line is running and 0 means the line is disconnected; is the line capacity; and Respectively represent the maximum and minimum output of the power supply.

[0085] Based on the above embodiment, the constraints also include:

[0086] Constraints on the output range of new energy sources:

[0087]

[0088] Line operation status statistics constraints:

[0089]

[0090] Load utility constraints of each node:

[0091]

[0092] Eliminate high failure probability transmission lines:

[0093]

[0094] Cables to be included first:

[0095]

[0096] In the formula, Predict output for new energy power stations; S loss,i is the utility value of the lost load at node i; is the maximum utility value of the lost load of node i; Ω is the set of transmission circuit faults; W Ca A collection of cable lines.

[0097] What needs to be understood here is that the node power balance constraint enables each node to prioritize the removal of secondary or low-priority loads when the power generation is insufficient; the line DC power flow constraint is the basis of the DC power flow model, which determines the distribution of power on each line and ensures the calculability of the power flow and the feasibility of actual operation; the line capacity constraint limits the line power flow to operate within its design capacity to avoid overload and line failure; the power output constraint ensures that the power supply operates within a safe range to avoid equipment damage or system instability caused by overload or low output operation; the continuous power supply constraint for loads at all levels will give priority to high-priority loads (such as hospitals and communication facilities) in disasters. Power supply guarantee, secondary loads are gradually removed according to the situation to ensure the power demand of important users; the new energy output range constraint is used to limit the actual output of new energy to not exceed the predicted value, so as to ensure the safety and reliability of dispatching; the line operation status statistics constraint is used to determine which lines can still operate normally after the typhoon disaster; the load utility constraint of each node limits the subjective tolerance of the node load loss; exclude high-failure probability transmission lines to avoid incorporating high-risk lines that are susceptible to typhoons into the backbone grid to improve power supply reliability; cable lines are included first because they are buried underground and are not easily affected by typhoon disasters, so they are the preferred choice of the backbone grid. These constraints together constitute the basis of the backbone grid search model, covering power balance, flow distribution, capacity limitation, load classification guarantee and other aspects, combined with the fluctuation characteristics of new energy and disaster risk factors, to provide systematic support for optimizing the operation of the power grid under typhoon disaster scenarios.

[0098] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for searching the backbone grid of a receiving-end power grid facing typhoon disasters, characterized in that: The following steps are involved: Simulate typhoon paths, evaluate the probability of transmission line failures at the receiving end power grid under different typhoon paths, compare the line failure probability with the preset threshold, and form a transmission line failure set; Considering the differences in disaster losses caused by shedding different types of loads and their scales, the functional relationship between load shedding amount and load shedding loss is simulated using utility function. Taking the minimum grid scale as the optimization goal, a backbone grid search model is constructed, and the backbone grid of the receiving-end power grid is obtained by solving the model.

2. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 1 is characterized in that: The simulated typhoon path includes a set of fault scenarios of power transmission lines of the receiving power grid under the simulated typhoon path. The typhoon path is related to its landing location, landing angle, moving speed and direction, and its calculation formula is: In the formula, (x l ,y l ) represents the position of the typhoon center at landfall; α is the angle between the coastline and the typhoon's direction of travel assuming that the typhoon moves in a straight line; v0(t0) is the forward speed of the typhoon at time t0 assuming that the typhoon moves in a straight line.

3. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 1 is characterized in that: In the transmission line fault set, the failure probability of the transmission line at a certain moment is expressed by the following formula: In the formula, v x,k (t0) represents the wind speed at the kth position of line x at time t0; v α represents the design wind speed of the line; μ and ν are coefficients; Δl represents the length of the line; P x,k (t0) is the failure probability of line x at time t0.

4. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 3 is characterized in that: The failure probability of the transmission line at a certain moment also includes setting a line failure probability threshold For lines with a failure probability exceeding the threshold, Then the line is selected into the fault set Ω, 5. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 1 is characterized in that: The utility function represents the user's subjective willingness to bear the loss caused by load shedding.

6. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 1 is characterized in that: The calculation formula for load shedding and load shedding loss of the receiving power grid under typhoon disaster is: In the formula, S loss Indicates load shedding loss; P ls Indicates load shedding; P set represents the threshold value of load shedding loss; e represents the natural logarithm.

7. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 1 is characterized in that: The backbone grid is the minimum scale grid that guarantees the power supply requirements of important users of the receiving power grid. With the minimum grid scale as the goal, combined with constraints such as avoiding high failure probability transmission channels and incorporating cables, a receiving power grid backbone grid search model is established.

8. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 7 is characterized in that: Set the objective function minN B , N B Indicates the number of backbone network lines.

9. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 8, characterized in that: The constraints include: Node power balance constraints: Line DC power flow constraints: Line capacity constraints: Power output constraints: Constraints on continuous reporting of loads at all levels: Where P i,t is the power output at node i at time t; Provide power for new energy power stations; l,t is the line flow; The first-level load, second-level load, and third-level load after load removal, ζ = 1, 2, 3; The load size of the first three levels of load shedding; b l is the line reactance; θ i,t and θ j,t is the voltage phase angle at both ends of the line; z l It is a 0-1 variable of line status, where 1 means the line is running and 0 means the line is disconnected; is the line capacity; P i and Respectively represent the maximum and minimum output of the power supply.

10. The method for searching the backbone grid of the receiving-end power grid facing typhoon disasters according to claim 9, characterized in that: The constraints also include: Constraints on the output range of new energy sources: Line operation status statistics constraints: Load utility constraints of each node: Eliminate high failure probability transmission lines: Cables to be included first: In the formula, Predict output for new energy power stations; S loss,i is the utility value of the lost load at node i; is the maximum utility value of the lost load of node i; Ω is the set of transmission circuit faults; W Ca A collection of cable lines.

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