A method and system for evaluating the reliability of a DC transmission protection system

Abstract

The present invention discloses a method and system for evaluating the reliability of a DC transmission protection system, and belongs to the technical field of power system reliability analysis. The method of the present invention comprises: obtaining historical defect data of a DC transmission protection system within a preset time period, determining index data of stable operation of the DC transmission protection system according to the historical defect data, and obtaining the reliability index of the DC transmission protection system according to the index data; determining the GO model of the DC transmission protection system according to the structure of the DC transmission protection system; using the reliability index as input data of the GO model, running the GO model, obtaining the output signal of the GO model, and determining the reliability of the DC transmission protection system according to the output signal. The reliability index determined by the present invention can fully reflect the operating status of the DC transmission protection system, and provide an effective basis for the operation and maintenance of the DC transmission protection system.

Description

Technical Field

[0001] The present invention relates to the technical field of power system reliability analysis, and more specifically, to a method and system for evaluating the reliability of a direct current transmission protection system. Background Art

[0002] As the first line of defense for the safe and stable operation of the DC transmission system, the reliability of the DC transmission protection system itself is very important to ensure the safe and stable operation of the DC transmission system. When a DC transmission protection system fails seriously, it will directly lead to DC locking, causing power loss and seriously affecting the safe and stable operation of the transmission system. Therefore, it is necessary to carry out reliability evaluation of the DC transmission protection system. Summary of the invention

[0003] In view of the above problems, the present invention proposes a method for evaluating the reliability of a DC transmission protection system, comprising:

[0004] Obtain historical defect data of the DC transmission protection system within a preset time period, determine index data of stable operation of the DC transmission protection system based on the historical defect data, and obtain reliability index of the DC transmission protection system based on the index data;

[0005] According to the structure of the DC transmission protection system, the GO model of the DC transmission protection system is determined;

[0006] The reliability index is used as the input data of the GO model, the GO model is run, the output signal of the GO model is obtained, and the reliability of the DC transmission protection system is determined according to the output signal.

[0007] Optional, historical defect data, including: measuring equipment defect data, measuring interface device defect data, DC transmission protection device defect data, three-out-of-two device defect data, tripping and secondary circuit defect data.

[0008] Optional, indicator data, including: failure rate and mean maintenance time for stable operation of each device in the DC transmission protection system.

[0009] Optional reliability indicators include: reliability index, average failure rate index, mean time between failures index and mean time to repair index.

[0010] Optionally, according to the structure of the DC transmission protection system, a GO model of the DC transmission protection system is determined, including:

[0011] According to the structure of the DC transmission protection system, determine the input boundary and output boundary of the system;

[0012] According to the structure, input boundary and output boundary of the DC transmission protection system, determine the operator model and the operation mode of the operator model of each device of the DC protection transmission system, operate the operator model according to the operation mode, and determine the reliability index and signal flow direction of the operator model of each device;

[0013] According to the operator model of each device, the reliability index of the operator model of each device and the signal flow, the GO model of the DC transmission protection system is established.

[0014] The present invention also proposes a system for evaluating the reliability of a DC power transmission protection system, comprising:

[0015] An acquisition module, which obtains historical defect data of the DC transmission protection system within a preset time period, determines index data of stable operation of the DC transmission protection system based on the historical defect data, and obtains reliability index of the DC transmission protection system based on the index data;

[0016] A model generation module determines the GO model of the DC transmission protection system according to the structure of the DC transmission protection system;

[0017] The reliability determination module uses the reliability index as the input data of the GO model, runs the GO model, obtains the output signal of the GO model, and determines the reliability of the DC transmission protection system according to the output signal.

[0018] Optionally, historical defect data includes: measuring equipment defect data, measuring interface device defect data, DC transmission protection device defect data, three-out-of-two device defect data, tripping data and secondary circuit defect data.

[0019] Optional, indicator data, including: failure rate and mean maintenance time for stable operation of each device in the DC transmission protection system.

[0020] Optional reliability indicators include: reliability index, average failure rate index, mean time between failures index and mean time to repair index.

[0021] Optionally, according to the structure of the DC transmission protection system, a GO model of the DC transmission protection system is determined, including:

[0022] According to the structure of the DC transmission protection system, determine the input boundary and output boundary of the system;

[0023] According to the structure, input boundary and output boundary of the DC transmission protection system, determine the operator model and the operation mode of the operator model of each device of the DC protection transmission system, operate the operator model according to the operation mode, and determine the reliability index and signal flow direction of the operator model of each device;

[0024] According to the operator model of each device, the reliability index of the operator model of each device and the signal flow, the GO model of the DC transmission protection system is established.

[0025] The reliability index determined by the present invention can fully reflect the operating status of the DC power transmission protection system and provide an effective basis for the operation and maintenance of the DC power transmission protection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for evaluating the reliability of a DC power transmission protection system according to the present invention;

[0027] Figure 2 A method for evaluating the reliability of a DC power transmission protection system according to the present invention is a DC power transmission protection system structure diagram;

[0028] Figure 3 A GO diagram of a DC power transmission protection system according to the present invention;

[0029] Figure 4 The present invention is a system structure diagram for evaluating the reliability of a DC power transmission protection system. DETAILED DESCRIPTION

[0030] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0031] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0032] The present invention proposes a method for evaluating the reliability of a DC transmission protection system. Figure 1 As shown, including:

[0033] Obtain historical defect data of the DC transmission protection system within a preset time period, determine index data of stable operation of the DC transmission protection system based on the historical defect data, and obtain reliability index of the DC transmission protection system based on the index data;

[0034] According to the structure of the DC transmission protection system, the GO model of the DC transmission protection system is determined;

[0035] The reliability index is used as the input data of the GO model, the GO model is run, the output signal of the GO model is obtained, and the reliability of the DC transmission protection system is determined according to the output signal.

[0036] Among them, historical defect data include: measuring equipment defect data, measuring interface device defect data, DC transmission protection device defect data, three-out-of-two device defect data, tripping and secondary circuit defect data.

[0037] Among them, the indicator data include: failure rate and average maintenance time of stable operation of each equipment in the DC transmission protection system.

[0038] Among them, reliability indicators include: reliability index, average failure rate index, mean failure interval index and mean maintenance time index.

[0039] According to the structure of the DC transmission protection system, the GO model of the DC transmission protection system is determined, including:

[0040] According to the structure of the DC transmission protection system, determine the input boundary and output boundary of the system;

[0041] According to the structure, input boundary and output boundary of the DC transmission protection system, determine the operator model and the operation mode of the operator model of each device of the DC protection transmission system, operate the operator model according to the operation mode, and determine the reliability index and signal flow direction of the operator model of each device;

[0042] According to the operator model of each device, the reliability index of the operator model of each device and the signal flow, the GO model of the DC transmission protection system is established.

[0043] The present invention will be further described below in conjunction with embodiments:

[0044] According to the structural composition of the DC transmission protection system, the structural diagram is as follows Figure 1 As shown, combined with historical defect data, equipment defects are divided into two parts: three-out-of-two redundant configuration-related protection device defects and dual configuration-related protection device defects. Then, device defects in different protection configuration modes are specifically subdivided into the following five categories: measurement equipment defects, measurement interface device defects, DC transmission protection device defects, three-out-of-two device defects, tripping and secondary circuit defects;

[0045] Collect historical defect data of DC transmission protection systems in converter stations in recent years;

[0046] Based on the historical defect data, the failure rate λ and mean maintenance time τ of the stable operation of each device in the DC transmission protection system are obtained. The indicators used in the reliability analysis of the DC transmission protection system include reliability, average failure rate, mean time between failures and mean maintenance time. The reliability characteristic quantities of the DC transmission protection system are as follows:

[0047] Maintenance rate:

[0048]

[0049] Mean time between failures:

[0050]

[0051] Reliability:

[0052]

[0053] According to the protection system structure, such as Figure 2 As shown, the input and output boundaries of the system are clearly defined, and the DC transmission protection system is divided into three-out-of-two redundant configuration protection related devices and dual configuration protection related devices. The related devices in different configuration modes are respectively composed of measuring equipment, measuring interface devices, DC transmission protection devices, three-out-of-two devices and tripping and secondary circuits. According to the functions of each part of the DC protection system, the measuring equipment is defined as the input boundary of the protection system, and the action results of the tripping and secondary circuits are defined as the output boundary of the system;

[0054] Determine the operator model and calculation process of each device in the DC transmission protection system. The basic data of the GO method operator include normal state probability, shutdown state probability, equivalent failure rate and equivalent maintenance rate. The basic data of the input signal are recorded as P S (1), P S (2), λ S , μ S , the basic data of the operator itself is recorded as P C (1), P C (2), λ C , μ C , the basic data of the operator output signal are recorded as P R (1), P R (2), λ R , μ R , GO diagram of DC transmission protection system, the operators used and the operator calculation process are as follows:

[0055] The measuring device is represented by a Type 5 operator. The Type 5 operator has no input and only one output signal, which is used as the input signal of the DC protection system. The calculation formula is:

[0056] PR (1) = P C (1), P R (2) = P C (2), λ R =λ C , μ R =μ C

[0057] Measuring equipment, measuring interface devices, DC transmission protection devices, tripping and secondary circuits are represented by type 1 operators. Type 1 operators are used to simulate a unit with 1 input signal and 1 output signal. The unit itself has 2 states. When the unit is in a normal state, the signal can pass. When the unit is in a fault maintenance state, the signal cannot pass. The input signal and operator in the GO diagram of the DC transmission protection system have a shutdown correlation. The shutdown fault number I = 1, so the calculation formula is as follows:

[0058] G1=P S (1) P C (1)

[0059] G2=P S (1) P C (2)+P S (2) P C (1)

[0060] P R (1) = G1 / (G1+G2)

[0061] P R (2) = G2 / (G1+G2)

[0062] λ R =λ S +λ C

[0063]

[0064] In the DC transmission system protection device, the logic relationship of the dual configuration protection device uses the type 2 operator or gate for logical calculation. The calculation formula is as follows:

[0065] Input signal data: P S1 (1), P S2 (2), λ S1 , μ S1

[0066] …………

[0067] P SM (1), P SM (2), λ SM , μ SM

[0068] Output signal data: P R (1), P R (2), λ R , μ R

[0069] The calculation formula of the OR gate input signal is as follows:

[0070]

[0071] P R (1) = 1-P R (2)

[0072]

[0073] λ R =μ R ·P R (2) / P R (1)

[0074] The type 10 operator represents an AND gate. When the two-out-of-three redundant configuration protection part and the duplex configuration protection part can correctly output the protection action information at the same time, the protection system can correctly output the action. Therefore, the logical relationship between them is represented by an AND gate. In the repairable system represented by the multiple input signals of the AND gate, as long as there is one fault repaired, there will be no normal output signal.

[0075] Input signal data: P S1 (1), P S2 (2), λ S1 , μ S1

[0076] …………

[0077] P SM (1), P SM (2), λ SM , μ SM

[0078] Output signal data: P R (1), P R (2), λ R , μ R

[0079] The calculation formula when the AND gate input signals are completely independent is as follows:

[0080]

[0081] P R (2) = 1-P R (1)

[0082]

[0083] μ R =λ R ·P R (1) / P R (2)

[0084] In the DC protection system, the 3-out-of-2 device has both logic judgment and action export functions, so it is represented by the type 11 operator M-out-of-K gate and the type 1 operator, and there is a shutdown correlation between the operators, I=1, where the M-out-of-K gate is a logical operator with M input signals and 1 output signal, indicating the logical relationship between input and output. At least K of the M input signals of the M-out-of-K gate must be successful for the output to be successful. The M-out-of-K gate operator has a total of 5 parameters M, K, I, L, and J. The meanings are as follows:

[0085] M—total number of units, total number of input signals;

[0086] K—success number, the minimum number of successful input signals required for the output signal to succeed;

[0087] I—number of shutdown faults, indicating shutdown related;

[0088] L—Maintenance man-hours, indicating maintenance related;

[0089] J—standby indication, indicating standby related;

[0090] When the M-take-K gate is used for calculation, its state transition rate is first determined based on the M-take-K gate parameters:

[0091] a i It represents the transition rate from the state with i-1 unit failures to the state with i unit failures, that is, the failure rate of the state when i-1 unit fails;

[0092]

[0093] b i It represents the transition rate from the state with i-unit failures to the state with i-1-unit failures, that is, the repair rate of the state with i-unit failures;

[0094]

[0095] According to the transfer rate a i and b i , and the probability of each state of the system is obtained as:

[0096] The probability of each state of the parallel structure:

[0097]

[0098] Parallel structure working probability:

[0099]

[0100] Parallel structure shutdown probability:

[0101]

[0102] Equivalent failure rate:

[0103]

[0104] Equivalent maintenance rate:

[0105]

[0106] In a series structure with M units, the reliability characteristic of each unit is:

[0107] P i (1), P i (2), λ i , μ i , i=1,…,M

[0108] In the DC transmission protection system, the shutdown of each unit in the series structure is related, and the shutdown fault number I=1. The failure rate and maintenance rate of the series structure are expressed as:

[0109]

[0110]

[0111] P R (1) = 1 / (1 + λ R / μ R )

[0112]

[0113] Establish the GO diagram of the DC transmission protection system, such as Figure 3 As shown, the GO diagram consists of two parts: operators and signal flows. Except for the three-out-of-two device, each operator represents a specific type of DC protection system equipment. The three-out-of-two device has both logic judgment and action export functions, and is represented by M-out-of-K gate logic operators and type 1 operators. The signal flow in the figure represents the flow of data information in the DC transmission protection system;

[0114] The operators in the GO diagram are composed of two numbers. The first number represents the operator type, and the second number represents the operator number. The arrow number is the information flow number, which is represented by only one number. The GO diagram of the DC transmission protection system consists of 22 functional operators and 3 logical operators in total.

[0115] Input the reliability parameters of all operators in the GO diagram of the DC transmission protection system, including failure rate and mean repair time.

[0116] Perform GO operation according to the operator's operation rules and signal flow.

[0117] The basis for the reliability evaluation of the DC transmission protection system as a whole is the reliability characteristic quantity of the output signal flow 25. When performing the GO operation, starting from the input operator, the operators are quantitatively calculated one by one along the signal flow sequence. For the operators on the same series branch, the series structure is quantitatively calculated to obtain their equivalent reliability parameters, which are represented by 11*, 12*, 13*, 17*, and 18*.

[0118] Then, according to the calculation method of M taking K gate operator, based on the characteristics of DC transmission protection system, the correlation parameters of parallel branches are: M = 3, K = 2, I = 2, J = 0, L = 1, and the reliability parameters of signal stream 16 are calculated;

[0119] According to the calculation formula of type 1 operator, type 2 OR gate operator, type 10 AND gate operator and common signal, GO operation is performed along the signal flow direction to obtain the reliability parameter of the output signal flow 25, and all the steady-state reliability characteristic quantities of the system can be obtained;

[0120] The reliability of the DC transmission protection system is analyzed using the reliability characteristic of the DC transmission protection system.

[0121] The reliability evaluation of the DC transmission protection system is calculated using the GO algorithm. The reliability evaluation indicators obtained include system reliability, average failure rate, mean time between failures and mean repair time. The reliability of the DC transmission protection system is the normal operating probability of the system. The closer the value is to 1, the higher the system reliability. The failure rate indicates the average number of failures per unit time due to protection device defects that cause the protection system to fail and fail to correctly export action information. When the value is greater than 1, the operation and maintenance personnel should be highly vigilant and carry out on-site equipment maintenance. The mean time between failures and the mean repair time can be used to provide a reference for the operation and maintenance personnel to formulate relevant maintenance plans. These reliability indicators can fully reflect the operating status of the DC transmission protection system and provide an effective basis for the operation and maintenance of the DC transmission protection system.

[0122] The following is a further explanation based on the defect data of the DC transmission protection system of a converter station from 2014 to 2018:

[0123] The relevant equipment types and reliability parameters obtained are shown in Table 1:

[0124] Table 1

[0125]

[0126] According to the reliability parameters of all operators in the GO diagram of the DC transmission protection system, the operation rules of the operators and the signal flow direction, GO operations are performed step by step starting from the system input signal to calculate the system output signal. Starting from input operators 1-5, the operators are quantitatively calculated one by one along the signal flow sequence. The operators on the same series branch have a shutdown-related structure, so the series structure of the operators must be quantitatively calculated separately to obtain their equivalent reliability parameters, which are represented by 11*, 12*, 13*, 17*, and 18*.

[0127] Then, according to the calculation method of M taking K gate operator and the characteristics of DC transmission protection system, the parallel branch correlation parameters are: M=3, K=2, I=2, J=0, L=1, and the calculated reliability parameters of signal stream 16 are shown in Table 2:

[0128] Table 2

[0129] Equivalent signal flow number Equivalent structure types <![CDATA[Failure rate / h -1 > Average maintenance time / h Average working probability 11*，12*，13* Shutdown-related series 0.00045662 6.00000000 0.99726776 17*，18* Shutdown series related 0.00011416 2.75000000 0.99968617 16 3 out of 2 in parallel 0.00000744 6.00000000 0.99995533

[0130] According to the calculation method of type 1 operator, OR gate and common signal, the reliability parameters of signal streams 21, 22, 23 and 24 are obtained. Finally, according to the calculation formula of type 10 operator and gate, the reliability parameter of output signal stream 25 is obtained, as shown in Table 3. All steady-state reliability characteristic quantities of the system are obtained, as shown in Table 4.

[0131] Table 3

[0132] Signal Stream Number <![CDATA[Failure rate / h -1 > Average maintenance time / h Average working probability 21 0.00011416 3.00000000 0.99965765 22 0.00011416 3.00000000 0.99965765 23 0.00016076 4.81981419 0.99961290 24 0.00000201 1.40476190 0.99999717 25 0.00016277 4.77761100 0.99922297

[0133] Table 4

[0134]

[0135] The reliability of the converter station is evaluated using the above calculation results as follows: The reliability of the DC protection system of the converter station is 0.99922297, which is a high reliability system. The average failure rate of the DC protection system of the converter station is 1.43 times per year, indicating that the DC protection system of the converter station fails 1.43 times per year due to defects in the DC protection equipment. When the DC protection system fails seriously, it will cause DC locking and serious losses. Therefore, equipment maintenance and repair work should be stepped up to reduce operating risks. The average failure interval time and average repair time can provide a reference for the operation and maintenance personnel to formulate a maintenance work plan, which is convenient for the application and arrangement of maintenance work.

[0136] The above analysis shows that the present invention can effectively provide a basis for reliability evaluation of DC power transmission protection systems, provide a reference for operation and maintenance of DC power transmission protection systems, and improve the operation and maintenance efficiency of DC power transmission protection systems.

[0137] According to the structure and function of each device in the DC transmission protection system, the present invention uses the GO algorithm operator to build a reliability evaluation model of the DC transmission protection system, and then uses the GO algorithm to calculate the reliability index of the DC transmission protection system to obtain reliability evaluation index parameters such as system reliability, average failure rate, mean time between failures and mean maintenance time, evaluate the DC transmission protection system, and provide an effective reference basis for the operation and maintenance of the DC transmission protection system.

[0138] The present invention also proposes a system 200 for evaluating the reliability of a DC power transmission protection system, such as Figure 4 As shown, including:

[0139] The acquisition module 201 acquires historical defect data of the DC transmission protection system within a preset time period, determines index data of stable operation of the DC transmission protection system according to the historical defect data, and acquires reliability index of the DC transmission protection system according to the index data;

[0140] The model generation module 202 determines the GO model of the DC transmission protection system according to the structure of the DC transmission protection system;

[0141] The reliability determination module 203 uses the reliability index as input data of the GO model, runs the GO model, obtains the output signal of the GO model, and determines the reliability of the DC power transmission protection system according to the output signal.

[0142] Among them, historical defect data include: measuring equipment defect data, measuring interface device defect data, DC transmission protection device defect data, three-out-of-two device defect data, tripping data and secondary circuit defect data.

[0143] Among them, the indicator data include: failure rate and average maintenance time of stable operation of each equipment in the DC transmission protection system.

[0144] Among them, reliability indicators include: reliability index, average failure rate index, mean failure interval index and mean maintenance time index.

[0145] According to the structure of the DC transmission protection system, the GO model of the DC transmission protection system is determined, including:

[0146] According to the structure of the DC transmission protection system, determine the input boundary and output boundary of the system;

[0147] According to the structure, input boundary and output boundary of the DC transmission protection system, determine the operator model and the operation mode of the operator model of each device of the DC protection transmission system, operate the operator model according to the operation mode, and determine the reliability index and signal flow direction of the operator model of each device;

[0148] According to the operator model of each device, the reliability index of the operator model of each device and the signal flow, the GO model of the DC transmission protection system is established.

[0149] The reliability index determined by the present invention can fully reflect the operating status of the DC power transmission protection system and provide an effective basis for the operation and maintenance of the DC power transmission protection system.

[0150] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0151] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0152] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0153] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0154] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0155] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for evaluating the reliability of a DC power transmission protection system, the method comprising: Obtain historical defect data of the DC transmission protection system within a preset time period, determine index data of stable operation of the DC transmission protection system based on the historical defect data, and obtain reliability index of the DC transmission protection system based on the index data; According to the structure of the DC transmission protection system, the GO model of the DC transmission protection system is determined; The reliability index is used as the input data of the GO model, the GO model is run, the output signal of the GO model is obtained, and the reliability of the DC transmission protection system is determined according to the output signal; The reliability index includes: reliability index, average failure rate index, mean time between failures index and mean maintenance time index; The calculation formula of the average maintenance time index, that is, the maintenance rate, is as follows: The calculation formula of the mean time between failures indicator is as follows: The calculation formula of the reliability index is as follows: Among them, μ is the value of the maintenance rate of the mean maintenance time indicator, τ is the mean maintenance time, and λ is the failure rate of stable operation of each device in the DC transmission protection system; The reliability index is used as input data of the GO model, the GO model is run, an output signal of the GO model is obtained, and the reliability of the DC power transmission protection system is determined according to the output signal, including: Determine the operator model and calculation process of each device in the DC transmission protection system. The basic data of the GO method operator include normal state probability, shutdown state probability, equivalent failure rate and equivalent maintenance rate. The basic data of the input signal are recorded as P S (1), P S (2), λ S , μ S , the basic data of the operator itself is recorded as P C (1), P C (2), λ C , μ C , the basic data of the operator output signal are recorded as P R (1), P R (2), λ R , μ R , GO diagram of DC transmission protection system, the operators used and the operator calculation process are as follows: The measuring device is represented by a Type 5 operator. The Type 5 operator has no input and only one output signal, which is used as the input signal of the DC protection system. The calculation formula is: P R (1)=P C (1),P R (2)=P C (2),l R =λ C ,m R =μ C Measuring equipment, measuring interface devices, DC transmission protection devices, tripping and secondary circuits are represented by type 1 operators. Type 1 operators are used to simulate a unit with 1 input signal and 1 output signal. The unit itself has 2 states. When the unit is in a normal state, the signal can pass. When the unit is in a fault maintenance state, the signal cannot pass. The input signal and operator in the GO diagram of the DC transmission protection system have a shutdown correlation. The shutdown fault number I = 1, so the calculation formula is as follows: G1=P S (1)·P C (1) G2=P S (1)·P C (2)+P S (2)·P C (1) P R (1)=G1 / (G1+G2) P R (2)=G2 / (G1+G2) l R =λ S +λ C In the DC transmission system protection device, the logic relationship of the dual configuration protection device uses the type 2 operator or gate for logical calculation. The calculation formula is as follows: Input signal data: P S1 (1), P S2 (2), λ S1 , μ S1 ………… P SM (1),P SM (2),l SM ,m SM Output signal data: P R (1), P R (2), λ R , μ R The calculation formula of the OR gate input signal is as follows: P R (1)=1-P R (2) l R =μ R ·P R (2) / P R (1) The type 10 operator represents an AND gate. When the two-out-of-three redundant configuration protection part and the duplex configuration protection part can correctly output the protection action information at the same time, the protection system can correctly output the action. Therefore, the logical relationship between them is represented by an AND gate. In the repairable system represented by the multiple input signals of the AND gate, as long as there is one fault repaired, there will be no normal output signal. Input signal data: P S1 (1), P S2 (2), λ S1 , μ S1 ………… P SM (1),P SM (2),l SM ,m SM Output signal data: P R (1), P R (2), λ R , μ R The calculation formula when the AND gate input signals are completely independent is as follows: P R (2)=1-P R (1) m R =λ R ·P R (1) / P R (2) In the DC protection system, the 3-out-of-2 device has both logic judgment and action output functions. Therefore, the type 11 operator M-out-of-K gate and the type 1 operator are used, and there is a shutdown correlation between the operators, I=1, where the M-out-of-K gate is a logical operator with M input signals and 1 output signal, indicating the logical relationship between input and output. At least K of the M input signals of the M-out-of-K gate must be successful for the output to be successful. The M-out-of-K gate operator has a total of 5 parameters M, K, I, L, J, and their meanings are as follows: M—total number of units, total number of input signals; K—success number, the minimum number of successful input signals required for the output signal to succeed; I—number of shutdown faults, indicating shutdown related; L—Maintenance man-hours, indicating maintenance related; J—standby indication, indicating standby related; When the M-take-K gate is used for calculation, its state transition rate is first determined based on the M-take-K gate parameters: a i It represents the transition rate from the state with i-1 unit failures to the state with i unit failures, that is, the failure rate of the state when i-1 unit fails; b i It represents the transition rate from the state with i-unit failures to the state with i-1-unit failures, that is, the repair rate of the state with i-unit failures; According to the transfer rate a i and b i , and the probability of each state of the system is obtained as: The probability of each state of the parallel structure: Parallel structure working probability: Parallel structure shutdown probability: Equivalent failure rate: Equivalent maintenance rate: In a series structure with M units, the reliability characteristic of each unit is: P i (1),P i (2),l i ,m i ,i=1,…,M In the DC transmission protection system, the shutdown of each unit in the series structure is related, and the shutdown fault number I=1. The failure rate and maintenance rate of the series structure are expressed as: P R (1)=1 / (1+λ R / m R ) Establish a GO diagram for the DC transmission protection system. The GO diagram consists of two parts: operators and signal flows. Except for the three-out-of-two device, each operator represents a specific device of the DC protection system. The three-out-of-two device has both logic judgment and action export functions and is represented by M-out-of-K gate logic operators and type 1 operators. The signal flow in the diagram represents the flow of data information in the DC transmission protection system. The operators in the GO diagram are composed of two numbers. The first number represents the operator type, and the second number represents the operator number. The arrow number is the information flow number, which is represented by only one number. The GO diagram of the DC transmission protection system consists of 22 functional operators and 3 logical operators in total. Input reliability parameters of all operators in the GO diagram of the DC transmission protection system, including failure rate and mean repair time; Perform GO operation according to the operator's operation rules and signal flow; The basis for the reliability evaluation of the DC transmission protection system as a whole is the reliability characteristic quantity of the output signal flow 25. When performing GO operation, starting from the input operator, the operators are quantitatively calculated one by one along the signal flow sequence. For the operators on the same series branch, the series structure is quantitatively calculated to obtain their equivalent reliability parameters, which are represented by 11*, 12*, 13*, 17*, 18*; Then, according to the calculation method of M taking K gate operator, based on the characteristics of DC transmission protection system, the correlation parameters of parallel branches are: M = 3, K = 2, I = 2, J = 0, L = 1, and the reliability parameters of signal stream 16 are calculated; According to the calculation formula of type 1 operator, type 2 OR gate operator, type 10 AND gate operator and common signal, GO operation is performed along the signal flow direction to obtain the reliability parameter of the output signal flow 25, and all the steady-state reliability characteristic quantities of the system can be obtained; The reliability of the DC transmission protection system is determined based on all steady-state reliability characteristic quantities.

2. The method according to claim 1, wherein the historical defect data comprises: Measuring equipment defect data, measuring interface device defect data, DC transmission protection device defect data, three-out-of-two device defect data, tripping and secondary circuit defect data.

3. The method according to claim 1, wherein the indicator data comprises: Failure rate and mean maintenance time for stable operation of each device in the DC transmission protection system.

4. The method according to claim 1, wherein determining the GO model of the DC power transmission protection system according to the structure of the DC power transmission protection system comprises: According to the structure of the DC transmission protection system, determine the input boundary and output boundary of the system; According to the structure, input boundary and output boundary of the DC transmission protection system, determine the operator model and the operation mode of the operator model of each device of the DC protection transmission system, operate the operator model according to the operation mode, and determine the reliability index and signal flow direction of the operator model of each device; According to the operator model of each device, the reliability index of the operator model of each device and the signal flow, the GO model of the DC transmission protection system is established.

5. A system for evaluating the reliability of a DC power transmission protection system, the system comprising: An acquisition module, which obtains historical defect data of the DC transmission protection system within a preset time period, determines index data of stable operation of the DC transmission protection system based on the historical defect data, and obtains reliability index of the DC transmission protection system based on the index data; A model generation module determines the GO model of the DC transmission protection system according to the structure of the DC transmission protection system; The reliability determination module uses the reliability index as input data of the GO model, runs the GO model, obtains the output signal of the GO model, and determines the reliability of the DC transmission protection system according to the output signal; The reliability index includes: reliability index, average failure rate index, mean time between failures index and mean maintenance time index; The calculation formula of the average maintenance time index, that is, the maintenance rate, is as follows: The calculation formula of the mean time between failures indicator is as follows: The calculation formula of the reliability index is as follows: Among them, μ is the value of the maintenance rate of the mean maintenance time indicator, τ is the mean maintenance time, and λ is the failure rate of stable operation of each device in the DC transmission protection system; The reliability index is used as input data of the GO model, the GO model is run, an output signal of the GO model is obtained, and the reliability of the DC power transmission protection system is determined according to the output signal, including: Determine the operator model and calculation process of each device in the DC transmission protection system. The basic data of the GO method operator include normal state probability, shutdown state probability, equivalent failure rate and equivalent maintenance rate. The basic data of the input signal are recorded as P S (1), P S (2), λ S , μ S , the basic data of the operator itself is recorded as P C (1), P C (2), λ C , μ C , the basic data of the operator output signal are recorded as P R (1), P R (2), λ R , μ R , GO diagram of DC transmission protection system, the operators used and the operator calculation process are as follows: The measuring device is represented by a Type 5 operator. The Type 5 operator has no input and only one output signal, which is used as the input signal of the DC protection system. The calculation formula is: P R (1)=P C (1),P R (2)=P C (2),l R =λ C ,m R =μ C Measuring equipment, measuring interface devices, DC transmission protection devices, tripping and secondary circuits are represented by type 1 operators. Type 1 operators are used to simulate a unit with 1 input signal and 1 output signal. The unit itself has 2 states. When the unit is in a normal state, the signal can pass. When the unit is in a fault maintenance state, the signal cannot pass. The input signal and operator in the GO diagram of the DC transmission protection system have a shutdown correlation. The shutdown fault number I = 1, so the calculation formula is as follows: G1=P S (1)·P C (1) G2=P S (1)·P C (2)+P S (2)·P C (1) P R (1)=G1 / (G1+G2) P R (2)=G2 / (G1+G2) l R =λ S +λ C In the DC transmission system protection device, the logic relationship of the dual configuration protection device uses the type 2 operator or gate for logical calculation. The calculation formula is as follows: Input signal data: P S1 (1), P S2 (2), λ S1 , μ S1 ………… P SM (1),P SM (2),l SM ,m SM Output signal data: P R (1), P R (2), λ R , μ R The calculation formula of the OR gate input signal is as follows: P R (1)=1-P R (2) l R =μ R ·P R (2) / P R (1) The type 10 operator represents an AND gate. When the two-out-of-three redundant configuration protection part and the duplex configuration protection part can correctly output the protection action information at the same time, the protection system can correctly output the action. Therefore, the logical relationship between them is represented by an AND gate. In the repairable system represented by the multiple input signals of the AND gate, as long as there is one fault repaired, there will be no normal output signal. Input signal data: P S1 (1), P S2 (2), λ S1 , μ S1 ………… P SM (1),P SM (2),l SM ,m SM Output signal data: P R (1), P R (2), λ R , μ R The calculation formula when the AND gate input signals are completely independent is as follows: P R (2)=1-P R (1) m R =λ R ·P R (1) / P R (2) In the DC protection system, the 3-out-of-2 device has both logic judgment and action output functions. Therefore, the type 11 operator M-out-of-K gate and the type 1 operator are used, and there is a shutdown correlation between the operators, I=1, where the M-out-of-K gate is a logical operator with M input signals and 1 output signal, indicating the logical relationship between input and output. At least K of the M input signals of the M-out-of-K gate must be successful for the output to be successful. The M-out-of-K gate operator has a total of 5 parameters M, K, I, L, J, and their meanings are as follows: M—total number of units, total number of input signals; K—success number, the minimum number of successful input signals required for the output signal to succeed; I—number of shutdown faults, indicating shutdown related; L—Maintenance man-hours, indicating maintenance related; J—standby indication, indicating standby related; When the M-take-K gate is used for calculation, its state transition rate is first determined based on the M-take-K gate parameters: a i It represents the transition rate from the state with i-1 unit failures to the state with i unit failures, that is, the failure rate of the state when i-1 unit fails; b i It represents the transition rate from the state with i-unit failures to the state with i-1-unit failures, that is, the repair rate of the state with i-unit failures; According to the transfer rate a i and b i , and the probability of each state of the system is obtained as: The probability of each state of the parallel structure: Parallel structure working probability: Parallel structure shutdown probability: Equivalent failure rate: Equivalent maintenance rate: In a series structure with M units, the reliability characteristic of each unit is: P i (1),P i (2),l i ,m i ,i=1,…,M In the DC transmission protection system, the shutdown of each unit in the series structure is related, and the shutdown fault number I=1. The failure rate and maintenance rate of the series structure are expressed as: P R (1)=1 / (1+λ R / m R ) Establish a GO diagram for the DC transmission protection system. The GO diagram consists of two parts: operators and signal flows. Except for the three-out-of-two device, each operator represents a specific device of the DC protection system. The three-out-of-two device has both logic judgment and action export functions and is represented by M-out-of-K gate logic operators and type 1 operators. The signal flow in the diagram represents the flow of data information in the DC transmission protection system. The operators in the GO diagram are composed of two numbers. The first number represents the operator type, and the second number represents the operator number. The arrow number is the information flow number, which is represented by only one number. The GO diagram of the DC transmission protection system consists of 22 functional operators and 3 logical operators in total. Input reliability parameters of all operators in the GO diagram of the DC transmission protection system, including failure rate and mean repair time; Perform GO operation according to the operator's operation rules and signal flow; The basis for the reliability evaluation of the DC transmission protection system as a whole is the reliability characteristic quantity of the output signal flow 25. When performing GO operation, starting from the input operator, the operators are quantitatively calculated one by one along the signal flow sequence. For the operators on the same series branch, the series structure is quantitatively calculated to obtain their equivalent reliability parameters, which are represented by 11*, 12*, 13*, 17*, 18*; Then, according to the calculation method of M taking K gate operator, based on the characteristics of DC transmission protection system, the correlation parameters of parallel branches are: M = 3, K = 2, I = 2, J = 0, L = 1, and the reliability parameters of signal stream 16 are calculated; According to the calculation formula of type 1 operator, type 2 OR gate operator, type 10 AND gate operator and common signal, GO operation is performed along the signal flow direction to obtain the reliability parameter of the output signal flow 25, and all the steady-state reliability characteristic quantities of the system can be obtained; The reliability of the DC transmission protection system is determined based on all steady-state reliability characteristic quantities.

6. The system according to claim 5, wherein the historical defect data comprises: Measuring equipment defect data, measuring interface device defect data, DC transmission protection device defect data, three-out-of-two device defect data, tripping and secondary circuit defect data.

7. The system according to claim 5, wherein the indicator data comprises: Failure rate and mean maintenance time for stable operation of each device in the DC transmission protection system.

8. The system according to claim 5, wherein determining the GO model of the DC power transmission protection system according to the structure of the DC power transmission protection system comprises: According to the structure of the DC transmission protection system, determine the input boundary and output boundary of the system; According to the structure, input boundary and output boundary of the DC transmission protection system, determine the operator model and the operation mode of the operator model of each device of the DC protection transmission system, operate the operator model according to the operation mode, and determine the reliability index and signal flow direction of the operator model of each device; According to the operator model of each device, the reliability index of the operator model of each device and the signal flow, the GO model of the DC transmission protection system is established.

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