Active defense method, device and system for power system cascading failure

Abstract

The embodiments of the present disclosure provide a method, system and device for active defense against chain failures in a power system, and relate to the field of safe operation of power systems. The method comprises: calculating the failure rate of each line under extreme meteorological conditions respectively, generating an initial planned disconnection line set according to the lines whose failure rate is higher than a preset threshold; performing flow and stability calculations on the initial planned disconnection line set based on the principle of minimum grid load loss, and determining the planned disconnection line set and the disconnection order of each line in the planned disconnection line set. In this way, some lines can be actively disconnected in the optimal order in sequence without fault, forming a power grid that can operate safely and stably in advance, without the need for complex accident chain searches and emergency blocking controls, significantly reducing the probability of generators, especially new energy sources, being disconnected from the grid after being impacted by faults, and minimizing power load losses and equipment damage while ensuring the safe operation of the power system.

Description

Technical Field

[0001] The present disclosure relates to the field of power system operation safety, and in particular to the field of active defense technology for power system cascading failures. Background Art

[0002] Extreme weather such as typhoons, blizzards, and lightning strikes are the main causes of cascading failures in power grids, which have a huge destructive effect on power grid equipment. Existing methods for preventing and controlling cascading failures mostly use theories such as self-organized criticality and small world to establish a dynamic model of the power grid, search and identify the power grid accident chain, and intervene in time during the expansion stage of the accident to reduce line power and remove some units or loads, thereby preventing the degree and scope of the accident from further expanding. The challenges faced by these cascading failure blocking methods include: 1) The initial fault selection takes less consideration of the impact of extreme weather, resulting in inaccurate identification of the accident chain, incorrect selection of blocking points and the size of the control quantity; 2) Due to the rapidity and weak anti-interference of the new energy dynamic response, the accident chain presents the characteristics of short evolution time, reduced related links, and high probability of occurrence. Therefore, the time left for blocking control is greatly shortened, and even the system accident has spread widely before it can be implemented. Therefore, a safe and stable active defense method for cascading failures is urgently needed. Summary of the invention

[0003] The present invention provides a method, device and system for active defense against cascading failures in an electric power system.

[0004] According to a first aspect of the present disclosure, a method for actively preventing cascading failures in a power system is provided, the method comprising:

[0005] The failure rate of each line under extreme meteorological conditions is calculated respectively, and an initial set of planned disconnected lines is generated based on the lines whose failure rate is higher than a preset threshold;

[0006] Based on the principle of minimum power grid load loss, flow and stability calculations are performed on the initial planned disconnection line set to determine the planned disconnection line set and the disconnection order of each line in the planned disconnection line set.

[0007] According to the above aspects and any possible implementation, an implementation is further provided, wherein respectively calculating the failure rate of each line under extreme meteorological conditions comprises:

[0008] Obtain the historical extreme weather level, duration, line location information, and average line failure rate within the specified time period of the target area, and obtain the total number of line failures and the number of failures of each line under extreme weather conditions;

[0009] The reciprocal of the product of the total number of line failures and the duration is multiplied by the number of failures of each line, the duration of the specified time period, and the average failure rate of the line in order to obtain the historical failure rate of each line under different weather levels and different durations;

[0010] Determine the linear coefficients of the historical failure rate of each line and the historical extreme weather level, and the historical failure rate of each line and the duration, and determine the quantitative linear relationship between the historical failure rate of each line and the historical extreme weather level and duration according to the linear coefficients;

[0011] The extreme weather forecast level and forecast duration are obtained, and the failure rate of each line of the power grid under the extreme weather forecast level and forecast duration is calculated according to the quantitative linear relationship.

[0012] According to the above aspect and any possible implementation manner, an implementation manner is further provided, wherein the method for calculating the preset threshold value includes:

[0013] Obtain the upper limit of the tolerance capacity of the line equipment under extreme weather conditions, the line load rate, and the short-term recovery rate of line faults after the protection control system of the equipment is actually configured to operate;

[0014] The reciprocal of the difference between the upper limit of the tolerance capacity and the line load rate is multiplied by the line fault short-time recovery rate to obtain a preset threshold value of the line fault rate.

[0015] According to the above aspects and any possible implementation, an implementation is further provided, wherein the flow and stability calculations are performed on the initial planned disconnection line set based on the principle of minimum power grid load loss, and the planned disconnection line set and the disconnection order of each line in the planned disconnection line set are determined, including:

[0016] Obtain power grid line parameter information;

[0017] In the power grid digital twin model, each line in the initial planned disconnected line set is disconnected respectively, and a simulation calculation is performed on the power grid flow after each line is disconnected respectively;

[0018] According to the result of the simulation calculation, a set of lines to be disconnected and a disconnection order of each line in the set of lines to be disconnected are determined.

[0019] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein determining the planned disconnection line set and the disconnection order of each line in the planned disconnection line set according to the result of the simulation calculation comprises:

[0020] Step (1): according to the result obtained by simulation calculation, i lines in the initial planned disconnection line set whose current is not overloaded are determined as the planned disconnection line set, wherein i is equal to the number of lines in the planned disconnection line set, and i=i-1;

[0021] Step (2): respectively obtaining the transient voltage and frequency of the i non-overloaded lines from a normal state to a disconnected state;

[0022] Step (3): Select the line with the smallest transient voltage and frequency change amplitude as the ath disconnected circuit, and delete it from the set of planned disconnected lines, where the initial value of a is 1, a=a+1;

[0023] Repeat steps (1), (2), (3) until i=0.

[0024] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein the method further includes:

[0025] According to the results of the simulation calculation, if the currents of all lines in the initially planned disconnected line set are overloaded, the load and generator output are adjusted according to the degree of line overload, and the adjusted grid line parameter information is re-acquired so as to re-perform the simulation calculation based on the adjusted grid line parameter information.

[0026] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein the method further includes:

[0027] When extreme weather occurs, each line in the planned disconnection line set is disconnected in sequence according to the line disconnection order to form a defense power grid line.

[0028] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein the method further includes:

[0029] Performing N-1 power flow calculation and N-2 stability calculation on the defense power grid line;

[0030] If the defensive power grid line is still overloaded and / or unstable, continue to reduce the load;

[0031] If the defense power grid line has no line overload and remains stable, the defense power grid line will be used as the final power grid form during the extreme weather.

[0032] According to a second aspect of the present disclosure, a device for active protection against cascading failures in a power system is provided. The device comprises:

[0033] A calculation module, used to calculate the failure rate of each line under extreme weather conditions, and generate a set of planned disconnected lines according to the lines whose failure rate is higher than a preset threshold;

[0034] The determination module is used to determine the disconnection order of each line in the planned disconnection line set based on the principle of minimum power grid load loss.

[0035] According to a third aspect of the present disclosure, there is provided a power system cascading failure active defense system, the system comprising:

[0036] Meteorological unit: sends extreme weather forecast information to user units, and sends extreme weather forecast information and historical extreme weather information to power grid units;

[0037] A power grid unit: used to implement the active defense method for cascading failures of a power system according to the first aspect of the present disclosure, and to send power outage information to a user unit;

[0038] User unit: Carry out load control and grid feedback based on extreme weather forecast information and power outage information.

[0039] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. The accompanying drawings are used to better understand the present solution and do not constitute a limitation of the present disclosure. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, among which:

[0041] Figure 1 is a schematic diagram of interaction between a meteorological department, a power grid enterprise and a power user provided by an embodiment of the present disclosure;

[0042] Figure 2 It is a flow chart of a method for active defense against cascading failures in a power system provided by an embodiment of the present disclosure;

[0043] Figure 3 is a flow chart for calculating the failure rate of each line of a power grid under extreme weather conditions provided by an embodiment of the present disclosure;

[0044] Figure 4 is a flowchart of determining the disconnection order of each line in a planned disconnection line set provided by an embodiment of the present disclosure;

[0045] Figure 5 is a system structure diagram of a regional power system provided by an embodiment of the present disclosure;

[0046] Figure 6 is a final power grid state diagram formed under extreme weather conditions provided by an embodiment of the present disclosure;

[0047] Figure 7 It is a block diagram of an active defense device for cascading failures of a power system provided by an embodiment of the present disclosure;

[0048] Figure 8 is a block diagram of an exemplary electronic device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0050] In addition, the term "and / or" in this article is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0051] The present disclosure provides a method for active defense against cascading failures in a power system, the method comprising: respectively calculating the failure rate of each line under extreme weather conditions, generating an initial planned disconnection line set according to the lines whose failure rate is higher than a preset threshold; performing flow and stability calculations on the initial planned disconnection line set based on the principle of minimum grid load loss, determining the planned disconnection line set and the disconnection order of each line in the planned disconnection line set. In this way, when extreme weather occurs, some lines can be actively disconnected in the optimal order in order without fault, forming an Nk grid (the total number of grid equipment is N, and the planned disconnection line is k) that can operate safely and stably in advance, with sufficient time to disconnect the lines, and there is no problem of mismatch between the accident chain and the actual situation and insufficient blocking control time in the accident.

[0052] Figure 1 A schematic diagram of the interaction between a meteorological department, a power grid enterprise and a power user in which an embodiment of the present disclosure can be implemented is shown, such as Figure 1 As shown,

[0053] The meteorological department 102 sends the future weather forecast data to the power grid company 104 and the power user 106, and also sends the historical weather data (extreme weather type, weather level, duration) to the power grid company 104; the power grid company 104 determines the order of disconnecting the lines and the load to be controlled in each round of disconnecting the lines based on the future weather forecast information and historical weather data received, and sends them to the power user 106; the power user 106 accepts the weather forecast and the power outage information issued by the power grid company, and makes a power outage plan in advance. It should be pointed out that the interaction between the three is not static. The meteorological department 102 will update the future weather forecast information in a rolling manner, and the power grid company 104 also needs to update the disconnection lines and pre-control loads in a timely manner according to the real-time weather forecast. In addition, the power user 106 is also required to cooperate closely during the disconnection operation, which is an alternating process of load control-disconnection-load control-disconnection.

[0054] Figure 2 2 shows a flow chart of a method 200 for actively preventing cascading failures in a power system in which an embodiment of the present disclosure can be implemented. Figure 2 As shown,

[0055] S210, respectively calculating the failure rate of each line under extreme weather conditions, and generating an initial planned disconnection line set according to the lines whose failure rate is higher than a preset threshold.

[0056] In some embodiments, extreme weather conditions refer to historically rare weather events that occur in a certain area within a certain period of time, such as typhoons, blizzards, lightning strikes, etc.

[0057] In some embodiments, the probability of failure of each line of the power grid under an impending extreme weather event can be determined by using statistical data of extreme weather level, duration, line faults, and geographical location information, as shown in the attached figure. Figure 3 As shown, determining the failure probability of each line of the power grid under an impending extreme weather event specifically includes the following steps:

[0058] Step (1): Count the meteorological level D of extreme meteorological events that occurred within a period of time T in the study area. k , duration T k According to the positioning information of power grid equipment, the average regional line failure rate λ0, the total number of failures С and the number of failures C of each line under extreme weather conditions within time T are counted. k .

[0059] Step (2): Based on the data provided in step 1, calculate the historical failure rate λ of each line under different weather levels and different duration conditions k , which is derived as follows:

[0060]

[0061] so,

[0062] Step (3): Determine the historical failure rate and weather level D of each line k Duration T k The linear relationship between them can be expressed as:

[0063] λ k =αD k +βT k (2)

[0064] Through steps (1) and (2), we can use the statistically obtained λ k , D k , T k The results are used to infer the values ​​of coefficients α and β.

[0065] According to the inferred α and β values, the failure rate λ of each line under the upcoming extreme weather conditions can be determined. k0 and forecast weather level D k0 and the forecast duration T k0 The binary function expression between:

[0066] λ k0 =αD k0 +βT k0 (3)

[0067] Step (4): According to the extreme weather forecast level D updated by the meteorological department k0 and forecast duration T k0 , using formula (3) to calculate the failure rate of each line in the power grid under the impending extreme weather event.

[0068] In some embodiments, the failure rates of the lines may be sorted from high to low, and the lines with failure rates greater than a preset threshold are selected as the initially planned disconnected lines, which are recorded as a set L.

[0069] In some embodiments, the upper limit of the tolerance capacity of the line equipment under extreme weather conditions, the line load rate, and the short-time recovery rate of the line fault after the actual configuration of the protection control system of the equipment is activated can be obtained, and the inverse of the difference between the upper limit of the tolerance capacity and the line load rate is multiplied by the short-time recovery rate of the line fault as the preset threshold of the line failure rate.

[0070] S220, performing power flow and stability calculations on the initial planned disconnection line set based on the principle of minimum power grid load loss, and determining the planned disconnection line set and the disconnection order of each line in the planned disconnection line set.

[0071] In some embodiments, the disconnection order of each line in the planned disconnection line set is taken as the optimal order. When extreme weather occurs, the planned disconnection line set can be proactively disconnected in the optimal order in sequence without fault, thereby forming an Nk power grid (the total number of power grid equipment is N, and the planned disconnection lines are k) that can operate safely and stably in advance.

[0072] In some embodiments, the disconnection order of each line in the planned disconnection line set is determined as shown in the attached Figure 4 As shown, the specific steps include:

[0073] Step (5): The power grid line parameter information can be obtained from the power dispatching department background, including: reading the grid structure, predicted load, generator, line, transformer electrical parameter information before the power grid line is disconnected, and building calculation data;

[0074] Step (6): disconnect each line in the initial planned disconnected line set L in the power grid digital twin model, and use the Newton-Raphson method to simulate power flow calculation based on the calculated data in step 5;

[0075] Step (7): Check the results of the simulation calculation, count the lines whose grid equipment currents do not exceed their current carrying limits after each line is disconnected, take the non-overloaded lines as the planned disconnected line set, calculate the transient voltage and frequency changes of these lines in the transition from normal state to disconnection one by one, select the line with the smallest amplitude change as the first disconnected line, record it as line i, and delete line i from the planned disconnected line set; if each line in the set L is overloaded after being disconnected, reduce the load and generator according to the degree of line overload, re-acquire the grid line parameter information, form new calculation data and repeat step (6).

[0076] Step (8): record the load loss caused by disconnecting the line i. The load loss includes two parts: one is the isolated node load formed after the line is disconnected, and the other is the load loss caused by the generator being disconnected from the grid during the transition process.

[0077] Step (9): According to the load loss and generator disconnection situation, adjust the grid calculation data after line i is disconnected, repeat steps 6-8, and obtain the second, third, ..., Nth (the number of lines in the planned disconnected line set) disconnected lines in turn, and actively reduce the load accordingly.

[0078] The first, second, third, ..., Nth disconnected lines determined in the above steps (6)-(9) are used as the disconnection order of each line in the planned disconnected line set.

[0079] In some embodiments, when extreme weather occurs, each line in the planned disconnection line set can be disconnected in sequence according to the line disconnection order to form a defensive power grid line.

[0080] In some embodiments, the above-mentioned defense power grid lines can be subjected to N-1 flow calculation and N-2 stability calculation respectively, wherein the N-1 flow calculation means that any component in the power system under normal operating mode (such as lines, generators, transformers, DC monopole, etc.) is fault-free or disconnected due to a fault, the power system should be able to maintain stable operation and normal power supply, other components are not overloaded, and the voltage and frequency are within the allowable range; the N-2 stability calculation means that after any two independent components (generators, transmission lines, transformers, etc.) among the N components of the power system fail and are removed, it should not cause power outages to users due to overload tripping of other lines, and should not destroy the stability of the system, and should not cause accidents such as voltage collapse.

[0081] In some embodiments, if N-1 loses stability due to equipment overload or N-2 failure, it is still necessary to reduce the load or actively disconnect the line. After the flow stability calculation is verified to be problem-free, the defense grid line will be used as the final grid form during extreme weather.

[0082] According to the embodiments of the present disclosure, the following technical effects are achieved:

[0083] (1) Actively disconnect the line before a chain accident occurs. There is no need to conduct complex chain accident chain identification and analysis. There is ample time to disconnect the line. There is no problem of mismatch between the accident chain and the actual situation and insufficient blocking control time during the accident.

[0084] (2) The lines are disconnected slowly and in sequence without any faults, which not only avoids the adverse effects of protection failure or malfunction, but also makes the voltage and frequency disturbances almost negligible compared with the simultaneous disconnection of line faults. This significantly reduces the probability of generators, especially new energy sources, being disconnected from the grid. Compared with the power grid that is passively formed by a short-term large disturbance shock, the load and equipment losses are greatly reduced, which has a high engineering application value.

[0085] According to the third embodiment of the present disclosure, the present disclosure is further described in detail, specifically taking a regional power system as the research object, and its system structure is shown in FIG. Figure 5 .

[0086] like Figure 5 As shown, "fire", "wind" and "light" refer to thermal power generation, wind power generation and solar power generation. The grid load is 2000MW. Historically, there have been many records of heavy rain in this area.

[0087] According to the rainstorm weather level and duration provided by the meteorological department, the power grid company obtained the partial line failure rate under the lightning weather conditions in July as shown in the following table:

[0088]

[0089] The power grid companies set the threshold at 0.45, taking into account the high cost of 220kV lines, the large amount of maintenance work and the long time required, the small number of important power users, and the personal safety during and after disasters.

[0090] It is thus determined that the disconnected lines are: 6-22, 15-17, 11-17.

[0091] After the flow and transient stability calculations, the order is determined as: 11-17, 15-17, 6-22, and the required pre-control loads are: 0MW, 0MW, 140MW respectively.

[0092] The failure rate of line 11-18 is lower than 0.45. However, after disconnecting the above high failure rate lines, 11-18 does not meet the N-1 safety requirements. 11-18 is in the connection between two regional power grids. If it is not disconnected, the load reduction at the sending end is too large. Directly disconnecting the load loss is small and meets the operation requirements. The best of the two is to actively disconnect 11-18 and then limit the load to 320WM. The final grid structure and state are as follows: Figure 6 shown.

[0093] According to the embodiments of the present disclosure, the following technical effects are achieved:

[0094] (1) Actively disconnect the line before a chain accident occurs. There is no need to conduct complex chain accident chain identification and analysis. There is ample time to disconnect the line. There is no problem of mismatch between the accident chain and the actual situation and insufficient blocking control time during the accident.

[0095] (2) The lines are disconnected slowly and in sequence without any faults, which not only avoids the adverse effects of protection failure or malfunction, but also makes the voltage and frequency disturbances almost negligible compared with the simultaneous disconnection of line faults. This significantly reduces the probability of generators, especially new energy sources, being disconnected from the grid. Compared with the power grid that is passively formed by a short-term large disturbance shock, the load and equipment losses are greatly reduced, which has a high engineering application value.

[0096] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the present disclosure is not limited by the order of the actions described, because according to the present disclosure, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present disclosure.

[0097] The above is an introduction to the method embodiment. The following is a further explanation of the scheme disclosed in the present invention through an apparatus embodiment.

[0098] Figure 7 A block diagram of a power system cascading failure active protection device 700 according to an embodiment of the present disclosure is shown. The device 700 includes:

[0099] The calculation module 710 is used to calculate the failure rate of each line under extreme weather conditions, and generate an initial planned disconnection line set according to the lines with failure rates higher than a preset threshold;

[0100] The determination module 720 is used to perform power flow and stability calculations on the initial planned disconnection line set based on the principle of minimum power grid load loss, and determine the planned disconnection line set and the disconnection order of each line in the planned disconnection line set.

[0101] In some embodiments, the calculation unit 710 is specifically used to: obtain the historical extreme weather level, duration, line location information and average line failure rate within a specified time period in the target area, and obtain the total number of line failures and the number of failures of each line under extreme weather conditions;

[0102] The reciprocal of the product of the total number of line failures and the duration is multiplied by the number of failures of each line, the duration of the specified time period, and the average failure rate of the line in order to obtain the historical failure rate of each line under different weather levels and different durations;

[0103] Determine the linear coefficients of the historical failure rate of each line and the historical extreme weather level, and the historical failure rate of each line and the duration, and determine the quantitative linear relationship between the historical failure rate of each line and the historical extreme weather level and duration according to the linear coefficients;

[0104] Obtain the extreme weather forecast level and forecast duration, and calculate the failure rate of each line of the power grid under the extreme weather forecast level and forecast duration according to the quantitative linear relationship.

[0105] In some embodiments, the determination unit 720 is specifically used to: obtain power grid line parameter information; disconnect each line in the initial planned disconnected line set in the power grid digital twin model, and simulate the power grid flow after each line is disconnected; and determine the planned disconnected line set and the disconnection order of each line in the planned disconnected line set based on the results of the simulation calculation.

[0106] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the described module can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0107] In the technical solution disclosed herein, the acquisition, storage and application of user personal information involved are in compliance with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0108] According to an embodiment of the present disclosure, the present disclosure also provides an electronic device, a readable storage medium and a computer program product.

[0109] Figure 8 A schematic block diagram of an electronic device 800 that can be used to implement an embodiment of the present disclosure is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present disclosure described and / or required herein.

[0110] The device 800 includes a computing unit 801, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 802 or a computer program loaded from a storage unit 808 into a random access memory (RAM) 803. In the RAM 803, various programs and data required for the operation of the device 800 can also be stored. The computing unit 801, the ROM 802, and the RAM 803 are connected to each other via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0111] A number of components in the device 800 are connected to the I / O interface 805, including: an input unit 806, such as a keyboard, a mouse, etc.; an output unit 807, such as various types of displays, speakers, etc.; a storage unit 808, such as a disk, an optical disk, etc.; and a communication unit 809, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 809 allows the device 800 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0112] The computing unit 801 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The computing unit 801 performs the various methods and processes described above, such as method 200. For example, in some embodiments, the method 200 may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit 808. In some embodiments, part or all of the computer program may be loaded and / or installed on the device 800 via ROM 802 and / or communication unit 809. When the computer program is loaded into RAM 803 and executed by the computing unit 801, one or more steps of the method 200 described above may be performed. Alternatively, in other embodiments, the computing unit 801 may be configured to perform the method 200 in any other appropriate manner (e.g., by means of firmware).

[0113] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0114] The program code for implementing the method of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0115] In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0116] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0117] The systems and techniques described herein may be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), and the Internet.

[0118] A computer system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The relationship of client and server is generated by computer programs running on respective computers and having a client-server relationship with each other. The server may be a cloud server, a server of a distributed system, or a server combined with a blockchain.

[0119] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of this disclosure can be achieved, and this document is not limited here.

[0120] The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for active defense against cascading failures in a power system, characterized in that: include: The failure rate of each line under extreme meteorological conditions is calculated respectively, and an initial set of planned disconnected lines is generated based on the lines whose failure rate is higher than a preset threshold; Based on the principle of minimum power grid load loss, flow and stability calculations are performed on the initial planned disconnection line set to determine the planned disconnection line set and the disconnection order of each line in the planned disconnection line set; including: Obtain power grid line parameter information; In the power grid digital twin model, each line in the initial planned disconnected line set is disconnected respectively, and a simulation calculation is performed on the power grid flow after each line is disconnected respectively; According to the result of the simulation calculation, determining a planned disconnection line set and a disconnection order of each line in the planned disconnection line set; comprising: Step (1): according to the result obtained by simulation calculation, i lines in the initial planned disconnection line set whose current is not overloaded are determined as the planned disconnection line set, wherein i is equal to the number of lines in the planned disconnection line set, and i=i-1; Step (2): respectively obtaining the transient voltage and frequency of the i non-overloaded lines from a normal state to a disconnected state; Step (3): Select the line with the smallest transient voltage and frequency change amplitude as the ath disconnected circuit, and delete it from the set of planned disconnected lines, where the initial value of a is 1, a=a+1; Repeat steps (1), (2), (3) until i=0.

2. The method according to claim 1, characterized in that: The respectively calculating the failure rate of each line under extreme weather conditions includes: Obtain the historical extreme weather level, duration, line location information, and average line failure rate within the specified time period of the target area, and obtain the total number of line failures and the number of failures of each line under extreme weather conditions; The reciprocal of the product of the total number of line failures and the duration is multiplied by the number of failures of each line, the duration of the specified time period, and the average failure rate of the line in order to obtain the historical failure rate of each line under different weather levels and different durations; Determine the linear coefficients of the historical failure rate of each line and the historical extreme weather level, and the historical failure rate of each line and the duration, and determine the quantitative linear relationship between the historical failure rate of each line and the historical extreme weather level and duration according to the linear coefficients; The extreme weather forecast level and forecast duration are obtained, and the failure rate of each line of the power grid under the extreme weather forecast level and forecast duration is calculated according to the quantitative linear relationship.

3. The method according to claim 1, characterized in that The method for calculating the preset threshold comprises: Obtain the upper limit of the tolerance capacity of the line equipment under extreme weather conditions, the line load rate, and the short-term recovery rate of the line fault after the protection control system of the actual equipment configuration is activated; The reciprocal of the difference between the upper limit of the tolerance capacity and the line load rate is multiplied by the line fault short-time recovery rate to obtain a preset threshold value of the line fault rate.

4. The method according to claim 1, characterized in that The method further comprises: According to the results of the simulation calculation, if the currents of all lines in the initially planned disconnected line set are overloaded, the load and generator output are adjusted according to the degree of line overload, and the adjusted grid line parameter information is re-acquired so as to re-perform the simulation calculation based on the adjusted grid line parameter information.

5. The method according to claim 1, characterized in that The method further comprises: When extreme weather occurs, each line in the planned disconnection line set is disconnected in sequence according to the line disconnection order to form a defense power grid line.

6. The method according to claim 5, characterized in that The method further comprises: Performing N-1 power flow calculation and N-2 stability calculation on the defense power grid line; If the defensive power grid line is still overloaded and / or unstable, continue to reduce the load; If the defense power grid line has no line overload and remains stable, the defense power grid line will be used as the final power grid form during the extreme weather.

7. An active defense device for cascading failures in a power system, characterized in that: include: A calculation module, used to calculate the failure rate of each line under extreme weather conditions, and generate an initial planned disconnection line set according to the lines with failure rates higher than a preset threshold; A determination module is used to perform power flow and stability calculations on the initial planned disconnection line set based on the principle of minimum power grid load loss, determine the planned disconnection line set and the disconnection order of each line in the planned disconnection line set; including: Obtain power grid line parameter information; In the power grid digital twin model, each line in the initial planned disconnected line set is disconnected respectively, and a simulation calculation is performed on the power grid flow after each line is disconnected respectively; According to the result of the simulation calculation, determining a planned disconnection line set and a disconnection order of each line in the planned disconnection line set; comprising: Step (1): according to the result obtained by simulation calculation, i lines in the initial planned disconnection line set whose current is not overloaded are determined as the planned disconnection line set, wherein i is equal to the number of lines in the planned disconnection line set, and i=i-1; Step (2): respectively obtaining the transient voltage and frequency of the i non-overloaded lines from a normal state to a disconnected state; Step (3): Select the line with the smallest transient voltage and frequency change amplitude as the ath disconnected circuit, and delete it from the set of planned disconnected lines, where the initial value of a is 1, a=a+1; Repeat steps (1), (2), (3) until i=0.

8. An active defense system for cascading failures in a power system, characterized in that: include: Meteorological unit: sends extreme weather forecast information to user units, and sends extreme weather forecast information and historical extreme weather information to power grid units; Grid unit: used to implement the active defense method for cascading failures of the power system as described in any one of claims 1 to 6, and send power outage information to the user unit; User unit: Carry out load control and grid feedback based on extreme weather forecast information and power outage information.

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