Fault location method and device based on multi-terminal differential protection device

Abstract

The application relates to a multi-terminal line fault location method and device. The method comprises the following steps: acquiring line information of each branch in a multi-terminal line; determining T-point voltages of each branch according to the line information of each branch; determining a fault branch according to the T-point voltages, and determining a T-side current of the fault branch according to the line information of the branch other than the fault branch; in the case that a PT line is disconnected in the fault branch, performing fault location on the fault branch according to the T-side current, real-time current and line impedance of the fault branch and the T-point voltage of the branch not subjected to fault; and in the case that a CT line is disconnected in the fault branch, performing fault location on the fault branch according to the T-side current, real-time voltage and line impedance of the fault branch and the T-point voltage of the branch not subjected to fault. Accordingly, the multi-terminal line fault location method can realize line fault location in the case that a PT line or a CT line is disconnected.

Description

Technical Field

[0001] This application relates to the field of power system relay protection technology, and in particular to a fault location method and device based on a multi-terminal differential protection device. Background Technology

[0002] With the large-scale integration of wind power into the power grid, multi-terminal lines are increasingly being used in high-voltage transmission lines to save on investment in power equipment and reduce land acquisition.

[0003] In multi-terminal lines, a fault at any end will affect the normal power supply to the remaining ends, so rapid fault clearing is required once a fault occurs. The longitudinal differential protection of multi-terminal lines is the main protection system. The differential protection and dual-end ranging share a communication channel and a single message to transmit information from each side. Differential protection is triggered by comparing the current differences on each side of the line, while dual-end ranging locates the fault based on the voltage and current on each side of the line and the line's impedance characteristics. Typically, dual-end ranging selects the sequence component for fault location and fault ranging based on the fault type. For phase-to-phase and three-phase faults, a positive-sequence network is used for ranging calculation, while for single-phase ground faults, a zero-sequence network is used to ensure accurate fault ranging, thus providing information for rapid fault recovery.

[0004] However, in the case of a PT or CT disconnection, the distance measurement calculation cannot be performed because the sequence components of voltage or current cannot be calculated. Summary of the Invention

[0005] Therefore, it is necessary to provide a multi-terminal line fault location method and device that can achieve line fault location in the event of PT or CT disconnection.

[0006] In a first aspect, this application provides a fault location method based on a multi-terminal differential protection device, the method comprising:

[0007] Obtain line information for each branch in a multi-terminal line, including PT disconnection status information, CT disconnection status information, real-time current, real-time voltage, and line impedance;

[0008] The voltage at point T of each branch is determined based on the line information of each branch.

[0009] The faulty branch is determined based on the voltage at each of the aforementioned T points, and the T-side current of the faulty branch is determined based on the line information of the branches other than the faulty branch.

[0010] In the case of a PT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

[0011] In the case of a CT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

[0012] In one embodiment, when a PT disconnection occurs in the faulty branch, fault location is determined based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch. This includes determining the fault distance of the faulty branch using a fault location method that combines the current at both ends with the voltage at one end, based on the voltage equation of the two ends of the line in a lumped parameter circuit.

[0013] In one embodiment, when a CT disconnection occurs in the faulty branch, fault location is determined based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch. This includes determining the fault distance of the faulty branch using a fault location method that combines the voltage at both ends with the current at one end, based on the T-side current, real-time voltage, and line impedance of the faulty branch, and the T-point voltage of the unfaulted branch.

[0014] In one embodiment, the line information further includes channel communication status information, and the method further includes: when there is a communication interruption in the faulty branch, the differential protection device that can receive information from the differential protection devices of all branches automatically switches to the host, and the host determines the fault distance of the faulty branch based on the T-side current, real-time current, real-time voltage and line impedance of the faulty branch and the T-point voltage of the non-faulty branch, based on the two-end ranging equation.

[0015] In one embodiment, the method further includes: if there is no PT disconnection, CT disconnection, or communication interruption in the faulty branch, determining the fault distance of the faulty branch based on a two-end ranging equation according to the T-side current, real-time current, real-time voltage, and line impedance of the faulty branch and the T-point voltage of the non-faulty branch.

[0016] In one embodiment, determining the T-point voltage of each branch based on the line information of each branch includes: determining the T-side loss voltage of the branch based on the product of the real-time current of the branch and the line impedance; and determining the T-point voltage of the branch based on the difference between the real-time voltage of the branch and the T-side loss voltage.

[0017] In one embodiment, determining the T-side current of the faulty branch based on the line information of branches other than the faulty branch includes: when the faulty branch has a PT disconnection, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of all branches other than the faulty branch; when the faulty branch does not have a PT disconnection but there is one PT disconnection branch in the multi-terminal line, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of the faulty branch and all branches other than the PT disconnection branch; when the faulty branch has a CT disconnection, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of all branches other than the faulty branch; when the faulty branch does not have a CT disconnection but there is one CT disconnection branch in the multi-terminal line, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of the faulty branch and all branches other than the CT disconnection branch.

[0018] Secondly, this application also provides a fault location device based on a multi-terminal differential protection device, the device comprising:

[0019] The line information acquisition module is used to acquire the line information of each branch in the multi-terminal line. The line information includes PT disconnection status information, CT disconnection status information, real-time current, real-time voltage and line impedance.

[0020] The T-point voltage determination module is used to determine the T-point voltage of each branch based on the line information of each branch.

[0021] The fault branch determination module is used to determine the fault branch based on the voltage at each T point, and to determine the T-side current of the fault branch based on the line information of branches other than the fault branch.

[0022] The fault location module is used to locate the fault in the faulty branch by means of the T-side current, real-time current and line impedance of the faulty branch and the T-point voltage of the non-faulty branch when there is a PT disconnection in the faulty branch.

[0023] The fault location module is also used to locate the fault branch based on the T-side current, real-time voltage, and line impedance of the fault branch, as well as the T-point voltage of the non-faulted branch, when a CT disconnection occurs in the fault branch.

[0024] Thirdly, this application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, performs the following steps:

[0025] Obtain line information for each branch in a multi-terminal line, including PT disconnection status information, CT disconnection status information, real-time current, real-time voltage, and line impedance;

[0026] The voltage at point T of each branch is determined based on the line information of each branch.

[0027] The faulty branch is determined based on the voltage at each of the aforementioned T points, and the T-side current of the faulty branch is determined based on the line information of the branches other than the faulty branch.

[0028] In the case of a PT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

[0029] In the case of a CT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

[0030] Fourthly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to perform the following steps:

[0031] Obtain line information for each branch in a multi-terminal line, including PT disconnection status information, CT disconnection status information, real-time current, real-time voltage, and line impedance;

[0032] The voltage at point T of each branch is determined based on the line information of each branch.

[0033] The faulty branch is determined based on the voltage at each of the aforementioned T points, and the T-side current of the faulty branch is determined based on the line information of the branches other than the faulty branch.

[0034] In the case of a PT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

[0035] In the case of a CT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

[0036] The aforementioned fault location method, apparatus, computer-readable storage medium, and computer equipment based on a multi-terminal differential protection device acquire line information of each branch in the multi-terminal line, including PT disconnection status information, CT disconnection status information, real-time current, real-time voltage, and line impedance; and determine the T-point voltage of each branch based on the line information of each branch; then determine the faulty branch based on the T-point voltage, and determine the T-side current of the faulty branch based on the line information of branches other than the faulty branch; in the case where there is a PT disconnection in the faulty branch, the fault location method, apparatus, computer-readable storage medium, and computer equipment based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the current of the branches that have not experienced a fault, determine the faulty branch based on the T-side current, real-time current, and line impedance of the faulty branch. The voltage at point T is used to locate the fault in the faulty branch. In cases where a current transformer (CT) is disconnected in the faulty branch, the fault location is determined based on the current at point T, real-time voltage, line impedance of the faulty branch, and the voltage at point T of the unfaulted branch. This approach fully utilizes the traditional communication channels of multi-terminal differential protection without altering the existing communication channels. By combining and analyzing information from each end of the line, the faulty branch is identified, and the multi-terminal ranging is converted into a two-terminal ranging from point T to the faulty branch. This enables fault location and fault ranging in the event of a PT or CT disconnection. Attached Figure Description

[0037] Figure 1 This is an application environment diagram of a multi-terminal line fault location method in one embodiment;

[0038] Figure 2 This is a flowchart illustrating a multi-terminal line fault location method in one embodiment;

[0039] Figure 3 This is a structural block diagram of a multi-terminal line fault location device in one embodiment. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] The fault location method based on a multi-terminal differential protection device provided in this application embodiment can be applied to, for example... Figure 1 The illustrated application environment is shown below. For example... Figure 1 As shown, the application environment includes: a 3-terminal longitudinal differential protection line, with a line protection device installed on each branch. This line protection device is a differential protection device. A fiber optic channel or wireless channel can be provided between any two line protection devices, such as... Figure 1The diagram illustrates M-RT, N-RT, and P-RT; U1, U2, and U3 represent the real-time voltages of each branch, and Ut represents the voltage at the T-junction. In this embodiment, the communication topology of the multi-terminal line can be a star topology or a ring topology, without specific limitations.

[0042] It should be noted that in a multi-terminal line, the possibility of multiple branches simultaneously experiencing PT disconnection, multiple branches simultaneously experiencing CT disconnection, multiple branches simultaneously experiencing communication interruption, and the possibility of the same branch simultaneously experiencing both PT and CT disconnection are all extremely small. Therefore, the actual line situation of this multi-terminal line can include: there is one and only one branch in the multi-terminal line that has experienced any of the following: PT disconnection, CT disconnection, and communication interruption; or, there is no branch in the multi-terminal line that has experienced any of the following: PT disconnection, CT disconnection, and communication interruption.

[0043] In one embodiment, such as Figure 2 As shown, a fault location method based on a multi-terminal differential protection device is provided, which is then applied to... Figure 1 The following explanation is based on a multi-terminal longitudinal differential protection line, including the following steps 201 to 205.

[0044] Step 201: Obtain the line information of each branch in the multi-terminal line. The line information includes PT disconnection status information, CT disconnection status information, real-time current, real-time voltage and line impedance.

[0045] In a multi-terminal line, each branch is equipped with a line protection device. Any one of these line protection devices can receive messages from the others. The messages can contain line information for its own branch. Any one of the line protection devices can be selected as the master line protection device (as the communication host), and the others as slave line protection devices (as communication slaves). When a fault occurs in the multi-terminal line, the master line protection device executes differential action logic, sending differential protection commands to each slave line protection device. The slave line protection devices receive the differential protection commands and trip their respective branches to clear the fault, thus achieving differential protection for the multi-terminal line.

[0046] The fault location device can obtain the line information of each branch from each slave line protection device, either from the main line protection device or from a fault location device based on a multi-terminal differential protection device. The line information may include line status information and line operating parameters. For example, the line status information may include PT (Power Transmission Unit) disconnection status information and CT (Collector Transmission Unit) disconnection status information. For example, the line operating parameters may include real-time current, real-time voltage, and line impedance.

[0047] Step 202: Determine the voltage at point T of each branch based on the line information of each branch.

[0048] The T-point voltage of each branch can be determined by the main line protection device or the fault location device based on the multi-terminal differential protection device, according to the line operating parameters of each branch; the T-point voltage of a branch is the voltage at point T of that branch. The presence of a PT disconnection or a CT disconnection can be determined by the main line protection device or the fault location device based on the PT disconnection status information and CT disconnection status information of the line. It is understandable that the T-point voltage cannot be calculated for branches with PT or CT disconnections.

[0049] Step 203: Determine the faulty branch based on the voltage at each T point, and determine the T-side current of the faulty branch based on the line information of the branches other than the faulty branch.

[0050] The faulty branch can be located by the main line protection device or a fault location device based on the T-point voltage of each of the aforementioned branches. Generally, when a branch fault occurs, the T-point voltage of that branch will be abnormal; for example, the T-point voltage of the faulty branch will be significantly different from that of the non-faulty branches. The presence or absence of abnormal T-point voltage can determine whether a fault has occurred in the main line, thus identifying the faulty branch. The identified faulty branch may be a branch with either a PT (potentially transformer) open circuit or a CT (current transformer) open circuit, or it may be a branch without either a PT or CT open circuit.

[0051] For example, if there is a T-point voltage in each branch that is significantly different from the other T-point voltages, it can be determined that the branch corresponding to the abnormal T-point voltage is faulty, thus identifying the branch as a faulty branch; if there is no T-point voltage in each branch that is significantly different from the other T-point voltages, it can be determined that the branch with either a PT open circuit or a CT open circuit is faulty, thus identifying the branch with either a PT open circuit or a CT open circuit as a faulty branch.

[0052] Once the faulty branch is located, the main line protection device or the fault location device based on the multi-terminal differential protection device can determine the T-side current of the faulty branch based on the line information of the branches other than the faulty branch; where the T-side current of the branch is the current at the T point of the branch.

[0053] Step 204: In the case of a PT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch.

[0054] The differential action logic can be executed by the main line protection device. After each slave line protection device receives the differential protection command and trips its respective branch, and the fault branch is located and it is determined that there is a PT disconnection in the fault branch, the main line protection device, the fault location device based on the multi-terminal differential protection device, or the line protection device on the side of the fault branch, perform fault location based on the T-side current, real-time current, line impedance of the fault branch, and the T-point voltage of the branch that has not experienced a fault.

[0055] Step 205: In the case of a CT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch.

[0056] The differential action logic can be executed by the main line protection device. After each slave line protection device receives the differential protection command and trips its respective branch, and the fault branch is located and it is determined that there is a CT disconnection in the fault branch, the main line protection device, the fault location device based on the multi-terminal differential protection device, or the line protection device on the side of the fault branch, perform fault location based on the T-side current, real-time voltage and line impedance of the fault branch and the T-point voltage of the branch that has not experienced a fault.

[0057] The multi-terminal line fault location method provided in this application involves a main line protection device or a fault location device based on a multi-terminal differential protection device acquiring line information of each branch in a multi-terminal line, determining the T-point voltage of each branch based on the line information, identifying the faulty branch based on the T-point voltage, and determining the T-side current of the faulty branch based on the line information of branches other than the faulty branch. In the case of a PT disconnection in the faulty branch, fault location is performed on the faulty branch based on the T-side current, real-time current, line impedance, and the T-point voltage of the non-faulty branches. Similarly, in the case of a CT disconnection in the faulty branch, fault location is performed on the faulty branch based on the T-side current, real-time voltage, line impedance, and the T-point voltage of the non-faulty branches. This application embodiment, without changing the traditional communication channel of longitudinal differential protection, makes full use of the traditional communication channel resources of multi-terminal differential protection. Any line protection device at any end can act as an information center, collecting and analyzing information from each end of the line to complement each other. It does not rely on the conditions or information of a single end of the line, but leverages the advantages of multi-source data information fusion to locate the faulty branch. By using the T-point voltage of the branch and the T-side current obtained from the real-time current of other sides, the multi-terminal ranging is converted into a two-terminal ranging from the T-point to the faulty branch. This realizes fault location and fault ranging of the line when there is a PT disconnection or a CT disconnection.

[0058] Optionally, step 204, in the case of a PT disconnection in the faulty branch, involves determining the fault distance of the faulty branch based on the T-side current, real-time current, line impedance of the faulty branch, and the T-point voltage of the unfaulted branch, including: determining the fault distance of the faulty branch based on the T-side current, real-time current, line impedance of the faulty branch, and the T-point voltage of the unfaulted branch, using the fault distance method of the current at both ends and the voltage at one end of the line based on the voltage equation of the two ends of the lumped parameter circuit.

[0059] When a faulty branch has a broken PT (potential transformer), the real-time voltage of the branch with the broken PT cannot be obtained, making it impossible to use the standard two-end distance measurement method (current and voltage at both ends) to locate the faulty branch. In this embodiment, the fault distance can be determined by the main line protection device, a fault location device based on a multi-terminal differential protection device, or the line protection device on the faulty branch side. This is based on the T-side current, real-time current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch, using the two-end voltage equation of the line based on a lumped parameter circuit. In other words, the line protection device on the faulty branch side uses a fault location method based on the current at both ends and the voltage at one end of the line, utilizing the pure resistance property of the transition resistor to solve for the fault distance, thus achieving fault location of the faulty branch. Furthermore, the distance measurement algorithm in this embodiment ignores the distributed capacitance of the line, and multi-terminal differential lines are generally not high-voltage long-distance transmission lines, resulting in higher distance measurement accuracy in practical engineering applications.

[0060] The voltage equations across the two ends of a line with lumped parameter current are as follows:

[0061]

[0062]

[0063] in, Let T be the voltage at point T of the branch where no fault has occurred, and x be the distance to the fault. Z is the current on the T side of the faulty branch. n The line impedance of the faulty branch. For grounding current, R F This is the transition resistance.

[0064] By using the equality of the real and imaginary parts, four equations can be obtained. The equations contain four unknowns: fault distance, grounding current, transition resistance, and real-time voltage that cannot be obtained due to PT disconnection. The number of equations equals the number of unknowns, thus the fault distance can be solved.

[0065] Optionally, step 205, in the case of a CT disconnection in the faulty branch, involves determining the fault distance of the faulty branch based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch. This includes determining the fault distance of the faulty branch based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch, using the fault distance method of comparing the voltage at both ends and the current at one end of the line, based on the voltage equation of the two ends of the line in the lumped parameter circuit.

[0066] When a current transformer (CT) is disconnected in a faulty branch, the real-time current of the branch with the disconnected CT cannot be obtained, making it impossible to use the standard two-end distance measurement method (current and voltage at both ends) to locate the fault. In this embodiment, the fault distance can be determined by the main line protection device, a fault location device based on a multi-terminal differential protection device, or the line protection device on the faulty branch side. This is based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch, using the voltage equation at both ends of the line based on a lumped parameter circuit. In other words, the line protection device on the faulty branch side uses a fault location method based on voltage at both ends and current at one end of the line, utilizing the pure resistance property of the transition resistor to solve for the fault distance, thus achieving fault location of the faulty branch. Furthermore, the distance measurement algorithm in this embodiment ignores the distributed capacitance of the line, and multi-terminal differential lines are generally not high-voltage long-distance transmission lines, resulting in higher distance measurement accuracy in practical engineering applications.

[0067] The voltage equations across the two ends of a line with lumped parameter current are as follows:

[0068]

[0069]

[0070] in, Let T be the voltage at point T of the branch where no fault has occurred, and x be the distance to the fault. Z is the current on the T side of the faulty branch. n The line impedance of the faulty branch. For grounding current, R F This is the transition resistance.

[0071] By using the equality of the real and imaginary parts, four equations can be obtained. The equations contain four unknowns: fault distance, grounding current, transition resistance, and real-time current that cannot be obtained due to CT disconnection. The number of equations equals the number of unknowns, thus the fault distance can be solved.

[0072] Optionally, the fault location method based on a multi-terminal differential protection device provided in this application embodiment further includes step 206: when there is a communication interruption in the fault branch, the differential protection device that can receive information from the differential protection devices of all branches automatically switches to the host, and the host determines the fault distance of the fault branch based on the T-side current, real-time current, real-time voltage and line impedance of the fault branch and the T-point voltage of the non-faulted branch based on the dual-terminal location equation.

[0073] exist Figure 1 In the application environment shown, when a communication failure occurs on one branch of a multi-terminal differential protection system, the differential protection operation remains unaffected. The line protection device capable of receiving messages from the other line protection devices automatically switches to become the communication master. That is, the communication master automatically switches to the line protection device with normal communication with the other line protection devices. The communication master executes the differential action logic, tripping all other line protection devices within the protection range. However, although the line protection device with the communication failure can receive the remote trip command to clear the fault, it cannot perform ranging calculations because it cannot obtain information from the other lines.

[0074] In this embodiment, when a faulty branch is located and a communication fault is determined to exist in it, the main line protection device can directly calculate the distance to the faulty branch using a standard two-end ranging method based on the faulty branch's T-side current, real-time current, real-time voltage, line impedance, and the T-point voltage of the unfaulted branch. This eliminates the need for the line protection device on the faulty branch's side to perform the ranging calculation, thus solving the problem of inability to perform fault ranging when a communication fault exists in the faulty branch. This ensures that even with a channel interruption, a certain level of ranging accuracy can still be guaranteed after the differential protection operates. Furthermore, the line status information can also include the line's channel communication status information, allowing the main line protection device to determine whether a communication fault exists in the faulty branch.

[0075] Optionally, the fault location method based on a multi-terminal differential protection device provided in this application embodiment further includes step 207: when there is no PT disconnection, CT disconnection, or communication interruption in the fault branch, the fault distance of the fault branch is determined based on the dual-terminal location equation according to the T-side current, real-time current, real-time voltage, and line impedance of the fault branch and the T-point voltage of the non-faulted branch.

[0076] In the absence of any communication interruption, PT disconnection, or CT disconnection in the faulty branch, the real-time current and real-time voltage of the branch can be obtained. Therefore, the faulty branch can be located using the standard two-end ranging method of two-end current and two-end voltage. In the embodiments of this application, the fault distance of the faulty branch can be determined by the main line protection device, the fault ranging device based on the multi-end differential protection device, or the line protection device on the faulty branch side, based on the T-side current, real-time current, real-time voltage and line impedance of the faulty branch and the T-point voltage of the non-faulty branch, according to the two-end ranging equation.

[0077] Optionally, step 202, determining the T-point voltage of each branch based on the line information of each branch, includes: determining the T-side loss voltage of the branch based on the product of the real-time current of the branch and the line impedance; and determining the T-point voltage of the branch based on the difference between the real-time voltage of the branch and the T-side loss voltage.

[0078] The main line protection device can determine the T-point voltage of each branch based on the real-time current, real-time voltage, and line impedance of each branch. For example, the T-point voltage U of a branch can be determined using the following formula. Tn :

[0079] U Tn =U n -I n Z n n≧3

[0080] Where n is the number of branches, I n Z represents the real-time current of the branch. n I is the line impedance of the branch. n Z n U is the voltage loss on the T side of the branch. n This is the real-time voltage of the branch. For example, the voltage U at the T1 contact corresponding to branch (1) is... T1 =U1-I1Z1; The voltage U at the T2 junction corresponding to branch (2) T2 =U2-I2Z2; The voltage U at the T3 junction corresponding to branch (3) T3 =U3-I3Z3.

[0081] In this embodiment, the T-point voltage of the branch is determined based on the real-time current, real-time voltage, and line impedance. The calculation method is simple and efficient, so the main line protection device can easily and efficiently locate the faulty branch based on the T-point voltage.

[0082] Optionally, step 203, determining the T-side current of the faulty branch based on the line information of branches other than the faulty branch, includes: when there is a PT disconnection in the faulty branch, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of all branches other than the faulty branch; when there is no PT disconnection in the faulty branch but there is one PT disconnection branch in the multi-terminal line, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of all branches other than the faulty branch and the branch with the PT disconnection; when there is a CT disconnection in the faulty branch, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of all branches other than the faulty branch; when there is no CT disconnection in the faulty branch but there is one CT disconnection branch in the multi-terminal line, determining the T-side current of the faulty branch based on the vector sum of the real-time currents of all branches other than the faulty branch and the branch with the CT disconnection.

[0083] For example, the T-side current of the faulty branch can be determined according to the following formula:

[0084]

[0085] Where m = n-1, I T I is the current on the T side of the faulty branch. i This represents the real-time current of a branch that has not experienced a fault.

[0086] In this embodiment, the T-side current of the faulty branch is determined based on the current vector sum of the branches other than the faulty branch in the multi-terminal line. This allows the line protection device to perform fault location based on the T-side current of the faulty branch, line information, and T-point voltage. This fully utilizes the traditional communication channel resources of the multi-terminal differential protection without changing the traditional communication channel of the longitudinal differential protection. It integrates and analyzes the line information from each end to complement each other, leveraging the advantages of multi-data information fusion to achieve fault location in the case of PT or CT disconnection.

[0087] The following provides a detailed description of the fault location method based on a multi-terminal differential protection device provided in the embodiments of this application:

[0088] The main line protection device can acquire line information from each branch of a multi-terminal line. This line information includes PT disconnection status information, CT disconnection status information, real-time current, real-time voltage, and line impedance. Based on the line information of each branch, the main line protection device determines the T-point voltage of each branch. The T-point voltage can be calculated using the formula U. Tn =U n -I n Z nThe main line protection device determines the faulty branch based on the voltage at each T point, and determines the T-side current of the faulty branch based on the line information of branches other than the faulty branch. The T-side current can be determined according to the formula for determining the T-side current of the faulty branch mentioned above.

[0089] When the main line protection device detects a PT disconnection in a faulty branch, the main line protection device or the line protection device on the faulty branch side can determine the fault distance of the faulty branch based on the T-side current, real-time current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch, using the voltage equations at both ends of the line in a lumped parameter circuit. In other words, the line protection device on the faulty branch side uses the fault distance measurement method of the current at both ends of the line and the voltage at one end, and uses the pure resistance property of the transition resistor to solve for the fault distance.

[0090] When the main line protection device detects a CT disconnection in a faulty branch, the main line protection device or the line protection device on the faulty branch side can determine the fault distance of the faulty branch based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch, using the voltage equations at both ends of the line in a lumped parameter circuit. In other words, the line protection device on the faulty branch side uses the fault distance measurement method of voltage at both ends of the line and current at one end, and uses the pure resistance property of the transition resistor to solve for the fault distance.

[0091] When the main line protection device detects a communication interruption in a faulty branch, it can directly calculate the distance to the faulty branch using the standard two-end ranging method based on the T-side current, real-time current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch. This eliminates the need for the line protection device on the faulty branch itself to perform the ranging calculation, thus solving the problem of being unable to perform fault ranging when there is a communication failure in the faulty branch.

[0092] If the main line protection device determines that there is no communication interruption, PT disconnection, or CT disconnection in the faulty branch, the main line protection device or the line protection device on the faulty branch side can determine the fault distance of the faulty branch based on the T-side current, real-time current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch, using the two-end ranging equation.

[0093] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0094] Based on the same inventive concept, this application also provides a multi-terminal line fault location device for implementing the multi-terminal line fault location method described above. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations in one or more embodiments of the multi-terminal line fault location device provided below can be found in the limitations of the multi-terminal line fault location method described above, and will not be repeated here.

[0095] In one embodiment, such as Figure 3 As shown, a fault location device based on a multi-terminal differential protection device is provided, including: a line information acquisition module 10, a T-point voltage determination module 20, a fault branch determination module 30, and a fault location module 40.

[0096] The line information acquisition module 10 is used to acquire the line information of each branch in the multi-terminal line. The line information includes PT disconnection status information, CT disconnection status information, real-time current, real-time voltage and line impedance.

[0097] The T-point voltage determination module 20 is used to determine the T-point voltage of each branch according to the line information of each branch.

[0098] The fault branch determination module 30 is used to determine the fault branch based on the voltage at each T point, and to determine the T-side current of the fault branch based on the line information of branches other than the fault branch.

[0099] The fault location module 40 is used to locate the fault in a faulty branch when the PT is disconnected, based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch; and to locate the fault in a faulty branch when the CT is disconnected, based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

[0100] In one embodiment, the fault location module 40 is used to determine the fault distance of the faulty branch based on the T-side current, real-time current, and line impedance of the faulty branch and the T-point voltage of the non-faulty branch, using the fault location method of the two-end voltage equation of the line in the lumped parameter circuit, by means of fault location method of the two-end current and one-end voltage.

[0101] In one embodiment, the fault location module 40 is used to determine the fault distance of the faulty branch based on the T-side current, real-time voltage, and line impedance of the faulty branch and the T-point voltage of the non-faulty branch, using the voltage equation of the two ends of the line in the lumped parameter circuit, and the fault location method of the voltage at one end and the current at the two ends.

[0102] In one embodiment, the fault location module 40 is used to automatically switch the differential protection device that can receive information from the differential protection devices of all branches when there is a communication interruption in the fault branch. The host determines the fault distance of the fault branch based on the two-end distance equation according to the T-side current, real-time current, real-time voltage and line impedance of the fault branch and the T-point voltage of the non-faulted branch.

[0103] In one embodiment, the fault location module 40 is used to determine the fault distance of the faulty branch based on the two-end distance equation, when there is no PT disconnection, CT disconnection and communication interruption in the faulty branch. This is done based on the T-side current, real-time current, real-time voltage and line impedance of the faulty branch and the T-point voltage of the non-faulty branch.

[0104] In one embodiment, the T-point voltage determination module 20 is used to determine the T-side loss voltage of the branch based on the product of the branch's real-time current and the line impedance; and to determine the T-point voltage of the branch based on the difference between the branch's real-time voltage and the T-side loss voltage.

[0105] In one embodiment, the fault branch determination module 30 is configured to: determine the T-side current of the fault branch based on the vector sum of the real-time currents of all branches other than the fault branch when a PT is disconnected in the fault branch; determine the T-side current of the fault branch based on the vector sum of the real-time currents of the fault branch and all branches other than the PT disconnected branch when no PT is disconnected in the fault branch but one PT disconnected branch exists in the multi-terminal line; determine the T-side current of the fault branch based on the vector sum of the real-time currents of the fault branch and all branches other than the PT disconnected branch when no PT is disconnected in the fault branch; determine the T-side current of the fault branch based on the vector sum of the real-time currents of the fault branch and all branches other than the PT disconnected branch when no CT is disconnected in the fault branch; and determine the T-side current of the fault branch based on the vector sum of the real-time currents of the fault branch and all branches other than the CT disconnected branch when no CT is disconnected in the fault branch but one CT disconnected branch exists in the multi-terminal line.

[0106] The various modules in the aforementioned fault location device based on multi-terminal differential protection can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0107] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0108] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0109] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0110] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0111] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0112] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A fault location method based on a multi-terminal differential protection device, characterized in that, The method includes: Obtain line information for each branch in a multi-terminal line, including PT disconnection status information, CT disconnection status information, real-time current, real-time voltage, and line impedance; The voltage at point T of each branch is determined based on the line information of each branch. The faulty branch is determined based on the voltage at each of the aforementioned T points, and the T-side current of the faulty branch is determined based on the line information of the branches other than the faulty branch. In the case of a PT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch. In the case of a CT disconnection in the faulty branch, the fault location is determined based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch.

2. The fault location method based on a multi-terminal differential protection device according to claim 1, characterized in that, In the case of a PT disconnection in the faulty branch, fault location is performed on the faulty branch based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch, including: Based on the T-side current, real-time current, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch, the fault distance of the faulty branch is determined by fault distance measurement using the two-end voltage and one-end voltage equation of the line based on the lumped parameter circuit.

3. The fault location method based on a multi-terminal differential protection device according to claim 1, characterized in that, In the case of a CT disconnection in the faulty branch, fault location is performed on the faulty branch based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the unfaulted branch, including: Based on the T-side current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch, the fault distance of the faulty branch is determined by fault distance measurement using the voltage at both ends and the current at one end, based on the voltage equation of the two ends of the line in the lumped parameter circuit.

4. The fault location method based on a multi-terminal differential protection device according to claim 1, characterized in that, The line information also includes channel communication status information, and the method further includes: In the event of a communication interruption in the faulty branch, the differential protection device that can receive information from the differential protection devices of all branches automatically switches to the host. The host determines the fault distance of the faulty branch based on the T-side current, real-time current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branches, using the two-end ranging equation.

5. The fault location method based on a multi-terminal differential protection device according to claim 1, characterized in that, The method further includes: If the faulty branch does not have any of the following: PT disconnection, CT disconnection, or communication interruption, the fault distance of the faulty branch is determined based on the two-end ranging equation, according to the T-side current, real-time current, real-time voltage, and line impedance of the faulty branch, as well as the T-point voltage of the non-faulty branch.

6. The fault location method based on a multi-terminal differential protection device according to claim 1, characterized in that, The step of determining the voltage at point T of each branch based on the line information of each branch includes: The T-side loss voltage of the branch is determined by multiplying the real-time current of the branch with the line impedance. The voltage at point T of the branch is determined based on the difference between the real-time voltage of the branch and the loss voltage on side T.

7. The fault location method based on a multi-terminal differential protection device according to claim 1, characterized in that, Determining the T-side current of the faulty branch based on the line information of branches other than the faulty branch includes: In the case of a PT disconnection in the faulty branch, the T-side current of the faulty branch is determined based on the vector sum of the real-time currents of all branches except the faulty branch. If there is no PT disconnection in the faulty branch and there is one PT disconnection branch in the multi-terminal line, the T-side current of the faulty branch is determined according to the vector sum of the real-time currents of all branches except the faulty branch and the PT disconnection branch. In the case of a CT disconnection in the faulty branch, the T-side current of the faulty branch is determined based on the vector sum of the real-time currents of all branches except the faulty branch. If there is no CT disconnection in the faulty branch and there is one CT disconnection branch in the multi-terminal line, the T-side current of the faulty branch is determined based on the vector sum of the real-time currents of all branches except the faulty branch and the CT disconnection branch.

8. A fault location device based on a multi-terminal differential protection device, characterized in that, The device includes: The line information acquisition module is used to acquire the line information of each branch in the multi-terminal line. The line information includes PT disconnection status information, CT disconnection status information, real-time current, real-time voltage and line impedance. The T-point voltage determination module is used to determine the T-point voltage of each branch based on the line information of each branch. The fault branch determination module is used to determine the fault branch based on the voltage at each T point, and to determine the T-side current of the fault branch based on the line information of branches other than the fault branch. The fault location module is used to locate the fault in the faulty branch by means of the T-side current, real-time current and line impedance of the faulty branch and the T-point voltage of the non-faulty branch when there is a PT disconnection in the faulty branch. The fault location module is also used to locate the fault branch based on the T-side current, real-time voltage, and line impedance of the fault branch, as well as the T-point voltage of the non-faulted branch, when a CT disconnection occurs in the fault branch.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

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