A flat cable fault identification and ranging method based on time domain multi-element electrical parameter identification

Abstract

The present application belongs to the technical field of flat cable fault detection, and particularly relates to a flat cable fault identification and ranging method based on time-domain multi-element electrical parameter identification, comprising: obtaining time-domain data and electrical parameters of each voltage and current of the flat cable double ends; writing relational equations of the flat cable double-end electrical quantities according to two types of situations of cracking and short circuit; substituting the time-domain data of the voltage and current into the equations; and judging the fault type according to the rules given by the present application. The present application can rapidly and reliably identify the cracking conductor of the cracking fault or the fault type and transition resistance size of the short circuit fault, and is not affected by the power supply and load in theory, and has high application value.

Description

Technical Field

[0001] This invention belongs to the field of flat cable fault detection technology, specifically relating to a method for flat cable fault identification and ranging based on time-domain multivariate electrical parameter identification. Background Technology

[0002] Flat cables are cables with a flat shape, typically used for transmitting power and communication signals. Compared to traditional round flat cables, flat cables offer greater flexibility and bending resistance, and are frequently used in buildings, tunnels, subways, ports, and other locations with specific requirements for flat cable wiring. During use, flat cables are often exposed to various harsh environmental conditions, and prolonged use and external environmental influences can easily lead to faults such as cracking and short circuits. These faults not only affect the normal operation of equipment but may also cause power system anomalies, equipment damage, and even safety accidents. Therefore, timely and effective identification of cracking or short-circuit faults in flat cables is particularly important.

[0003] Currently, fault location methods for flat cables include the fundamental frequency vector method, traveling wave method, time-domain model method, and artificial intelligence method. While the fundamental frequency vector method is simple in principle, it cannot accurately measure fault distance if the transition resistance is time-varying. The traveling wave-based location method is unaffected by factors such as transition resistance and line structure, but flat cables are typically short, leading to complex traveling wave reflection processes and difficulty in accurately identifying the wavefront. The artificial intelligence method provides accurate distance measurement, but requires extensive data training, resulting in high time and resource costs. Furthermore, the model depends on specific environments and datasets, requiring retraining or adjustment to maintain adaptability when the environment changes. The time-domain model method is unaffected by high-frequency harmonics and can still accurately measure fault distance for time-varying transition resistance faults. However, the time-domain model method is currently mainly applied to single-core cables, while flat cables have a more complex structure and numerous electrical coupling parameters in their equivalent circuit model, making it impossible to directly apply existing methods. In addition, the above analytical methods are primarily used to identify short-circuit faults, with little application to cracking faults in flat cables. Therefore, research on fault identification and distance measurement for flat cables is of great significance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that, in the prior art, the above-mentioned analysis methods are mainly used to identify short-circuit faults, but cannot identify cracks in flat cables, and cannot quickly measure the fault distance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for fault identification and ranging of flat cables based on time-domain multivariate electrical parameter identification includes the following steps:

[0007] Step 1: Obtain time-domain data and electrical parameters of voltage and current at both ends of the flat cable;

[0008] Step 2: Establish the equation relating the electrical quantities at both ends of the flat cable to the cracking condition;

[0009] Step 3: Determine whether the flat cable cracking is a cracking fault based on the cracking criteria;

[0010] Step 4: Establish the short-circuit relationship equations for the electrical quantities at both ends of the flat cable;

[0011] Step 5: Determine whether it is a short circuit fault based on the short circuit criterion for flat cables;

[0012] Step 6: Determine the faulty conductor, fault distance, fault type, and transition resistance based on the short circuit conditions.

[0013] By employing the above technical solution, this method can quickly and reliably identify crack or short-circuit faults, and accurately determine the faulty conductor, fault distance, fault type, and transition resistance. This facilitates rapid response and problem-solving, reducing equipment downtime and maintenance costs.

[0014] Further, in step 1: obtain the voltage and current at both ends of the flat cable. , , , Where i = A, SA, B, SB, C, SC, D, E, F, representing phase A conductor, phase A shielding layer, phase B conductor, phase B shielding layer, phase C conductor, phase C shielding layer, power core, control core, and grounding core, respectively; , These represent the voltage and current of phase i at the beginning of the flat cable, respectively. , These represent the voltage and current of phase i at the end of the flat cable, respectively; obtain the resistance of the flat cable grounding wire. The unit resistance matrix R, the unit inductance matrix L, and the unit capacitance matrix C, as well as the length l of the flat cable.

[0015] By adopting the above technical solution and accurately measuring the voltage and current at both ends, it can be ensured that subsequent analysis is based on real and reliable electrical data. This is a prerequisite for accurate fault identification. Measuring the voltage and current of phase A, phase B, phase C, their shielding layer, power core, control core, and grounding core respectively can comprehensively describe the electrical characteristics of the flat cable and help to distinguish different types of faults more precisely.

[0016] Furthermore, the currents at both ends and the voltages of the three-phase conductor core, power core, and control core are obtained through measurement, while the shielding layer voltage and grounding core voltage at each end are calculated using the following formula:

[0017] .

[0018] By adopting the above technical solution and organizing the measured voltage and current values ​​into a matrix form, the processing of large amounts of data can be simplified. Matrix operations can efficiently manage and calculate this data, reducing algorithmic complexity. Using matrix representation helps to establish a more concise mathematical model to describe the electrical behavior in flat cables. This makes analyzing electrical relationships under crack or short-circuit conditions more intuitive and easier to understand. Matrix operations also allow the use of a wealth of linear algebra tools and techniques.

[0019] Furthermore, the voltage and current at the tail ends , , , This forms a voltage and current matrix at both ends. , , , :in,

[0020] ;

[0021] ;

[0022] ;

[0023] ;

[0024] Establish a fault resistance matrix and inductor matrix :

[0025] in, ;

[0026] .

[0027] Furthermore, in steps 2 and 3, based on the lumped parameter model, the relationship equations for the cracking of the two-terminal electrical quantities are established: where,

[0028] ;

[0029] ;

[0030] in, The sampling interval is denoted as .

[0031] By adopting the above technical solution, the lumped parameter model approximates the distributed characteristics (such as resistance, inductance, and capacitance) of flat cables as lumped components. This greatly simplifies the mathematical model, making calculations more efficient and easier to implement. Because of the lumped parameter model, complex partial differential equations can be avoided, and relatively simple algebraic equations can be used to describe the system behavior. This is crucial for real-time monitoring and rapid response. Although based on the lumped parameter assumption, the model is still applicable to flat cables of different lengths and types, simply by adjusting the parameter matrices R, L, and C appropriately.

[0032] Furthermore, the electrical quantities at the beginning and end of the flat cable are substituted into the fault resistance matrix. and inductor matrix And solve for it, and obtain the solution. and Substitute the elements at the corresponding positions into the flat cable cracking criterion below to determine whether a cracking fault has occurred. The specific steps include:

[0033] Step 21: If , and If the condition is met, then it is determined that a cracking failure has occurred in phase j, where, , These are the elements at the j-th row and j-th column positions of the unit resistance matrix R and the inductance matrix L, respectively, and m is the reliability coefficient used to adjust the sensitivity of the criterion and ensure the accuracy of fault identification.

[0034] Step 22: For any , or All of these hold true; define a fault conductance matrix containing unknowns. .

[0035] By employing the above technical solution, and by substituting the calculated R'(t) and L'(t) matrix elements into the given criteria, it is possible to determine very accurately which phase has experienced a cracking fault. This precision is crucial for rapid repair and reduced downtime. Steps 21 and 22 provide a clear set of logical rules for determining the fault type.

[0036] Furthermore, in steps 4 and 5, based on the lumped parameter model, the short-circuit relationship equations for the two-terminal electrical quantities are established:

[0037] ;

[0038] ;

[0039] Where x is the fault distance, The voltage matrix at the fault point;

[0040] The specific expression is as follows:

[0041] ;

[0042] Substitute the voltage and current matrices from both ends and solve for x and .

[0043] By employing the aforementioned technical solution, through mathematical modeling and numerical solution, the exact location of a short-circuit fault can be determined with remarkable precision. This high-precision fault location capability is crucial for rapid repair, significantly reducing troubleshooting time and maintenance costs. This method is not only applicable to simple conductor-to-shield short circuits but can also handle more complex fault modes, increasing the system's versatility and adaptability, enabling it to cope with various possible fault scenarios. The relational equations based on the lumped parameter model can be directly calculated using existing electrical measurement data, without the need for additional physical testing or equipment disassembly.

[0044] Furthermore, the obtained x and Substitute the elements into the flat cable short-circuit criterion to determine whether a short-circuit fault has occurred:

[0045] Step 31: Solving for any short-circuit fault type, and Established If so, it is determined to be a short circuit fault, and the faulty conductor, fault distance, fault type and transition resistance are determined;

[0046] Step 32: For the solution results of all short-circuit fault types, x and If none of the above criteria for short circuit in flat cables are met, then it is determined that there is no short circuit fault.

[0047] By adopting the above technical solution and verifying the specific conditions of different types of short-circuit faults, fault types can be classified more precisely. This helps to take targeted repair measures and improve maintenance efficiency. Step 32 ensures that if none of the possible short-circuit fault types meet the short-circuit criterion, it can be clearly determined that there is no short-circuit fault, reducing the possibility of false alarms. Comparing the calculation results with the actual measurement data and verifying the fault hypothesis through the short-circuit criterion improves the reliability of the diagnostic results. Rigorous short-circuit criterion checks can effectively avoid misjudgments caused by numerical errors or other factors, enhancing the reliability of the system. By solving for x, the physical location of the fault can be accurately determined, enabling maintenance personnel to quickly arrive at the site and implement repairs.

[0048] Furthermore, The specific expression is as follows:

[0049] A short circuit occurs between phase m conductor and phase m shielding layer, where m represents phases A, B, and C. Assume the transition resistance is... :

[0050] m represents phase A:

[0051]

[0052] m is phase B:

[0053]

[0054] m is phase C:

[0055] ;

[0056] The m-phase conductor and the m-phase shielding layer are short-circuited to ground. Let m represent phases A, B, and C. Assume the transition resistance between the m-phase conductor and the m-phase shielding layer is... The transition resistance of the m-phase shielding layer to ground is :

[0057] m represents phase A:

[0058]

[0059] m is phase B:

[0060]

[0061] m is phase C:

[0062] ;

[0063] The B-phase conductor, B-phase shielding layer, n-phase shielding layer, and n-phase conductor are short-circuited, where n represents phases A and C. Assume the transition resistance between the B-phase conductor and the B-phase shielding layer is... The transition resistance between phase B shielding layer and phase n shielding layer is The transition resistance between the n-phase conductor and the n-phase shielding layer is :

[0064] n represents phase A:

[0065]

[0066]

[0067] n represents phase C:

[0068]

[0069] ;

[0070] Short circuit in phase C conductor, phase C shielding layer and power core:

[0071] Let the transition resistance between the C-phase conductor and the C-phase shielding layer be... The transition resistance between the C-phase shielding layer and the power core is :

[0072] ;

[0073] If the power core or control core is short-circuited to ground, the transition resistance is assumed to be... :

[0074] Power core ground short circuit:

[0075]

[0076] Control core ground short circuit:

[0077] ;

[0078] The power core and control core are short-circuited. Assume the transition resistance between the power core and control core is... :

[0079] ;

[0080] The power core and control core are short-circuited to ground. Assume the transition resistance between the power core and control core is... The transition resistance to ground is :

[0081]

[0082] .

[0083] By adopting the above technical solutions and defining each possible short-circuit fault mode in detail, different types of faults can be identified more accurately. By modeling the transition resistance under various fault modes, similar but different fault conditions can be distinguished, thereby improving the accuracy of fault classification. Each expression considers specific transition resistance values, which helps to quantify the severity of the fault and provide specific parameters for repair work. These expressions can be directly applied to the numerical solution process to help determine the fault location and other key information. For flat cable systems containing multiple conductors, such as three-phase power lines plus shielding and other auxiliary lines, these expressions can effectively handle complex short-circuit conditions.

[0084] The beneficial effects of this invention are as follows:

[0085] 1. This invention can quickly and reliably identify the fault type and transition resistance of cracked conductors or short-circuit faults according to the given rules, without being affected by power supply and load, and has high application value.

[0086] 2. This invention introduces a time-domain multivariate electrical parameter identification method, combines it with a lumped parameter model to establish relational equations under cracking and short-circuit conditions, and uses rigorous criteria for fault diagnosis. This method can not only accurately locate the fault position (including the fault conductor and fault distance), but also accurately identify the fault type (such as cracking or short circuit) and its transition resistance, improving the speed and accuracy of fault diagnosis, reducing troubleshooting time and maintenance costs, and ensuring the efficient operation of the power system.

[0087] 3. This invention can quickly respond to and handle potential safety hazards in real-time monitoring, promptly detect and resolve cracking and short-circuit faults, and prevent them from evolving into more serious accidents. Through automated decision support and detailed fault report generation, it enhances the safety and reliability of the system. Precise fault classification helps to take targeted repair measures, reduce unnecessary maintenance work, extend the life of flat cables, and indirectly reduce the cost of replacing new flat cables. Attached Figure Description

[0088] Figure 1 This is a flowchart of the present invention;

[0089] Figure 2 A schematic diagram of a cracked shielding layer fault in phase A of a flat cable;

[0090] Figure 3 This is a schematic diagram of a short circuit fault in a flat cable.

[0091] Among them, 1-flat cable; 2-A phase shielding layer; 3-A phase conductor; 4-insulation layer; 5-B phase conductor; 5-B phase shielding layer; 6-C phase conductor; 6-C phase shielding layer; 7-power core; 8-control core; 9-grounding core; 10-outer sheath. Detailed Implementation

[0092] The invention will now be further described with reference to the accompanying drawings.

[0093] like Figure 1 , Figure 2 and Figure 3 As shown, a method for fault identification and ranging of flat cable 1 based on time-domain multivariate electrical parameter identification includes the following steps:

[0094] Step 1: Obtain time-domain data and electrical parameters of voltage and current at both ends of the flat cable;

[0095] Step 2: Establish the equation relating the electrical quantities at both ends of the flat cable to the cracking condition;

[0096] Step 3: Determine whether the flat cable cracking is a cracking fault based on the cracking criteria;

[0097] Step 4: Establish the short-circuit relationship equations for the electrical quantities at both ends of the flat cable;

[0098] Step 5: Determine whether it is a short circuit fault based on the short circuit criterion for flat cables;

[0099] Step 6: Determine the faulty conductor, fault distance, fault type, and transition resistance based on the short circuit conditions.

[0100] First, obtain the voltage and current at both ends of the flat cable 1. , , , Where i = A, SA, B, SB, C, SC, D, E, F, representing phase A conductor 3, phase A shielding layer 2, phase B conductor 5, phase B shielding layer 51, phase C conductor 6, phase C shielding layer 61, power core 7, control core 8, and grounding core 9, respectively. , These represent the voltage and current of phase i at the beginning of the flat cable, respectively. , These represent the phase i voltage and current at the end of flat cable 1, respectively. Obtain the resistance of the grounding wire of flat cable 1. Unit resistance matrix R, unit inductance matrix L, and unit capacitance matrix C, as well as the length l of the flat cable 1;

[0101] The outermost layer of the flat cable 1, A-phase conductor 3, A-phase shielding layer 2, B-phase conductor 5, B-phase shielding layer 51, C-phase conductor 6, C-phase shielding layer 61, power core 7, control core 8, and grounding core 9 is wrapped with an outer sheath 10.

[0102] (2) Based on the voltage and current measured at both ends in step (1) , , , This forms a voltage and current matrix at both ends. , , , :

[0103]

[0104]

[0105]

[0106]

[0107] (3) Define the fault resistance matrix containing unknowns. and inductor matrix :

[0108]

[0109]

[0110] (4) Based on the lumped parameter model, establish the relationship equation between the cracking conditions of the two-terminal electrical quantities:

[0111]

[0112]

[0113] in, The sampling interval is denoted as .

[0114] (5) Based on the relational equation described in step (4), substitute the voltage and current matrices at both ends and solve for the solution. and .

[0115] (6) Solve the solution obtained in step (5) and Substitute the element at the corresponding position into the following criterion to determine whether a cracking fault has occurred:

[0116] (a) If it exists , and If the condition is met, then it is determined that a cracking failure has occurred in phase j, where, , These are the elements at the j-th row and j-th column positions of the unit resistance matrix R and the inductance matrix L, respectively. m is a reliability coefficient used to adjust the sensitivity of the criterion and ensure the accuracy of fault identification. In this embodiment, m is taken as... .

[0117] (b) If for any , or If all are true, proceed to step (7).

[0118] (7) Define the fault conductance matrix containing unknowns. , The specific expression is as follows:

[0119] ① A short circuit occurs between the m-phase conductor and the m-phase shielding layer, where m represents A, B, and C. Assume the transition resistance is... :

[0120] m represents phase A:

[0121]

[0122] m is phase B:

[0123]

[0124] m is phase C:

[0125]

[0126] ② A short circuit between the m-phase conductor and the m-phase shielding layer to ground, where m represents A, B, and C. Assume the transition resistance between the m-phase conductor and the m-phase shielding layer is... The transition resistance of the m-phase shielding layer to ground is :

[0127] m represents phase A:

[0128]

[0129] m is phase B:

[0130]

[0131] m is phase C:

[0132]

[0133] ③ A short circuit occurs between phase B conductor 5, phase B shielding layer 51, phase n shielding layer, and phase n conductor, where n represents phases A and C. Assume the transition resistance between phase B conductor 5 and phase B shielding layer 51 is... The transition resistance between phase B shielding layer 51 and phase n shielding layer is The transition resistance between the n-phase conductor and the n-phase shielding layer is :

[0134] n represents phase A:

[0135]

[0136]

[0137] n represents phase C:

[0138]

[0139]

[0140] ④ Short circuit between phase C conductor 6, phase C shielding layer 61, and power core 7:

[0141] Let the transition resistance between phase C conductor 6 and phase C shielding layer 61 be... The transition resistance between the C-phase shielding layer 61 and the power core 7 is :

[0142]

[0143] ⑤ If the power core 7 or control core 8 is short-circuited to ground, the transition resistance is set to be... :

[0144] Power core 7 ground short circuit:

[0145]

[0146] Control chip 8 ground short circuit:

[0147]

[0148] ⑥ When power core 7 and control core 8 are short-circuited, assume the transition resistance between power core 7 and control core 8 is... :

[0149]

[0150] ⑦ Power core 7 and control core 8 are short-circuited to ground. Assume the transition resistance between power core 7 and control core 8 is... The transition resistance to ground is :

[0151]

[0152]

[0153] (8) Based on the lumped parameter model, establish the short-circuit relationship equations for two-terminal electrical quantities:

[0154]

[0155]

[0156] Where x is the fault distance, This is the voltage matrix at the fault point. The specific expression is as follows:

[0157]

[0158] (9) Based on the relational equation described in step (8), substitute the voltage and current matrices at both ends and solve for x and y. .

[0159] (10) Solve for x and x in step (9) Substitute the elements in the table into the following criterion to determine whether a short-circuit fault has occurred:

[0160] (a) If the solution result for any short-circuit fault type, and Established, If the condition is met, it is determined to be a short-circuit fault. Based on the established criteria, the faulty conductor, fault distance, fault type, and transition resistance are determined.

[0161] (b) If the solution results for all short-circuit fault types, x and If none of the above criteria are met, then it is determined that there is no short-circuit fault.

[0162] This diagram illustrates a cracked shielding layer fault in the flat cable 1 of the present invention. Taking the cracking of the A-phase flat cable 1 as an example, the present invention provides a method for fault identification and ranging of the flat cable 1 based on time-domain multivariate electrical parameter identification. The cracking fault identification includes the following steps:

[0163] (1) Measure the voltage and current at both ends of the flat cable 1. , , , Where i = A, SA, B, SB, C, SC, D, E, F, representing phase A conductor 3, phase A shielding layer 2, phase B conductor 5, phase B shielding layer 51, phase C conductor 6, phase C shielding layer 61, power core 7, control core 8, and grounding core 9, respectively. , These represent the voltage and current of phase i at the beginning of the flat cable, respectively. , Representing the phase i voltage and current at the end of flat cable 1, respectively, obtain the grounding wire resistance of flat cable 1. The unit resistance matrix R, the unit inductance matrix L, and the unit capacitance matrix C, as well as the length l of the flat cable 1.

[0164] (2) Based on the voltage and current measured at both ends in step (1) , , , This forms a voltage and current matrix at both ends. , , , :

[0165]

[0166]

[0167]

[0168]

[0169] (3) Define the fault resistance matrix containing unknowns. and inductor matrix :

[0170]

[0171]

[0172] (4) Based on the lumped parameter model, establish the relationship equation between the voltage and current at both ends regarding the cracking condition:

[0173]

[0174]

[0175] in, The sampling interval is denoted as .

[0176] (5) Based on the relational equation described in step (4), substitute the voltage and current matrices at both ends and solve for the solution. and .

[0177] (6) Solve the solution obtained in step (5) and Substitute the element at the corresponding position into the following criterion to determine whether a cracking fault has occurred:

[0178] (a) If it exists , and If the condition is met, then it is determined that a cracking failure has occurred in phase j, where, , These are the elements at the j-th row and j-th column positions of the unit resistance matrix R and the inductance matrix L, respectively. m is a reliability coefficient used to adjust the sensitivity of the criterion and ensure the accuracy of fault identification. In this embodiment, m is taken as... .

[0179] (b) If for any , or If all are true, proceed to step (7).

[0180] After identifying the cracking fault as described above, if flat cable 1 is not cracked, then short-circuit fault identification is performed. Figure 2The diagram shown is a schematic representation of a short-circuit fault in the flat cable 1 according to the present invention. Taking a short circuit between phase A conductor 3 and phase A shielding layer 2 in the flat cable 1 as an example, the fault identification and ranging method for the flat cable 1 based on time-domain multivariate electrical parameter identification of the present invention includes the following steps for short-circuit fault identification:

[0181] (7) Define the fault conductance matrix containing unknowns. , The specific expression is as follows:

[0182] ① A short circuit occurs between the m-phase conductor and the m-phase shielding layer, where m represents phases A, B, and C. Assume the transition resistance is... :

[0183] m represents phase A:

[0184]

[0185] m is phase B:

[0186]

[0187] m is phase C:

[0188]

[0189] ② A short circuit between the m-phase conductor and the m-phase shielding layer to ground, where m represents phases A, B, and C. Assume the transition resistance between the m-phase conductor and the m-phase shielding layer is... The transition resistance of the m-phase shielding layer to ground is :

[0190] m represents phase A:

[0191]

[0192] m is phase B:

[0193]

[0194] m is phase C:

[0195]

[0196] ③ A short circuit occurs between phase B conductor 5, phase B shielding layer 51, phase n shielding layer, and phase n conductor, where n represents phases A and C. Assume the transition resistance between phase B conductor 5 and phase B shielding layer 51 is... The transition resistance between phase B shielding layer 51 and phase n shielding layer is The transition resistance between the n-phase conductor and the n-phase shielding layer is :

[0197] n represents phase A:

[0198]

[0199]

[0200] n represents phase C:

[0201]

[0202]

[0203] ④ Short circuit between phase C conductor 6, phase C shielding layer 61, and power core 7:

[0204] Let the transition resistance between phase C conductor 6 and phase C shielding layer 61 be... The transition resistance between the C-phase shielding layer 61 and the power core 7 is :

[0205]

[0206] ⑤ If the power core 7 or control core 8 is short-circuited to ground, the transition resistance is set to be... :

[0207] Power core 7 ground short circuit:

[0208]

[0209] Control chip 8 ground short circuit:

[0210]

[0211] ⑥ When power core 7 and control core 8 are short-circuited, assume the transition resistance between power core 7 and control core 8 is... :

[0212]

[0213] ⑦ Power core 7 and control core 8 are short-circuited to ground. Assume the transition resistance between power core 7 and control core 8 is... The transition resistance to ground is :

[0214]

[0215]

[0216] (8) Based on the lumped parameter model, establish the short-circuit relationship equations for the voltage and current at both ends:

[0217]

[0218]

[0219] Where x is the fault distance, This is the voltage matrix at the fault point. The specific expression is as follows:

[0220]

[0221] (9) Based on the relational equation described in step (8), substitute the voltage and current matrices at both ends and solve for x and y. .

[0222] (10) Solve for x and x in step (9) Substitute the elements in the table into the following criterion to determine whether a short-circuit fault has occurred:

[0223] (a) If the solution result for any short-circuit fault type, and Established, If the condition is met, it is determined to be a short-circuit fault. Based on the established criteria, the faulty conductor, fault distance, fault type, and transition resistance are determined.

[0224] (b) If the solution results for all short-circuit fault types, x and If none of the above criteria are met, then it is determined that there is no short-circuit fault.

[0225] The above-described process of the present invention is also applicable to cracks in phase A, phase B, phase B shielding layer 51, phase C, phase C shielding layer 61, power core 7, control core 8, and grounding core 9 of flat cable 1, as well as the other 6 types of short circuit faults.

[0226] To verify the effectiveness and reliability of this invention, a simulation model of the flat cable 1 was built on PSCAD / EMTDC, simulating two fault types: cracking and short circuit. The cracking fault identification results were...

[0227] As shown in Table 1

[0228] Table 1

[0229] The short-circuit fault identification results are shown in Table 2:

[0230] Table 2

[0231] This invention can quickly and reliably identify the fault type and transition resistance of cracked conductors or short-circuit faults. Theoretically, this invention is unaffected by power supply and load, and has high application value.

[0232] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A method for fault identification and ranging of flat cables based on time-domain multivariate electrical parameter identification, characterized in that, Includes the following steps: Step 1: Obtain time-domain data and electrical parameters of voltage and current at both ends of the flat cable (1); Step 2: Establish the relationship equation between the electrical quantities at both ends of the flat cable (1) regarding the cracking situation; Step 3: Determine whether the cracking fault is due to cracking based on the cracking criteria of the flat cable (1); Step 4: Establish the short-circuit relationship equations for the electrical quantities at both ends of the flat cable (1); Step 5: Determine whether it is a short circuit fault based on the short circuit criterion of the flat cable (1); Step 6: Determine the faulty conductor, fault distance, fault type, and transition resistance based on the short circuit conditions; In step 1: Obtain the voltage and current at both ends of the flat cable (1). , , , Where i = A, SA, B, SB, C, SC, D, E, F, representing A-phase conductor (3), A-phase shielding layer (2), B-phase conductor (5), B-phase shielding layer (51), C-phase conductor (6), C-phase shielding layer (61), power core (7), control core (8), and grounding core (9), respectively. , These represent the voltage and current of phase i at the beginning of the flat cable (1), respectively. , Let i represent the voltage and current of phase i at the end of the flat cable (1), respectively; and obtain the grounding resistance of the flat cable (1). The unit resistance matrix R, the unit inductance matrix L, and the unit capacitance matrix C, as well as the length l of the flat cable (1); The currents at both ends and the voltages of the three-phase conductor core, power core (7), and control core (8) are obtained by measurement. The shielding layer voltage and grounding core (9) voltage of each phase at both ends are calculated by the following formula: Voltage and current at both ends , , , This forms a voltage and current matrix at both ends. , , , :in, ； ； ； ； Establish a fault resistance matrix and inductor matrix : in, ; ； In steps 2 and 3, based on the lumped parameter model, the relationship equations for the cracking of the two-terminal electrical quantities are established: where, ； ； in, The sampling interval; Substitute the voltage and current matrices at both ends of the flat cable (1) into the cracking relationship equation and solve for the solution. and Substitute the corresponding element into the cracking criterion for flat cable (1) below to determine whether a cracking fault has occurred. The specific steps include: Step 21: If , and If the condition is met, then it is determined that a cracking failure has occurred in phase j, where, , These are the elements at the j-th row and j-th column positions of the unit resistance matrix R and the inductance matrix L, respectively, and m is the reliability coefficient used to adjust the sensitivity of the criterion and ensure the accuracy of fault identification. Step 22: For any , or If all conditions are met, establish the fault conductance matrix. ; In steps 4 and 5, based on the lumped parameter model, the short-circuit relationship equations for the two-terminal electrical quantities are established: ； ； Where x is the fault distance, This represents the voltage matrix at the fault point. The specific expression is as follows: ； Substitute the voltage and current matrices from both ends and solve for x and ; The obtained x and Substitute the elements in the formula into the short-circuit criterion of the flat cable (1) to determine whether a short-circuit fault has occurred: Step 31: Solving for any short-circuit fault type, and Established, If so, it is determined to be a short circuit fault, and the faulty conductor, fault distance, fault type and transition resistance are determined; Step 32: For the solution results of all short-circuit fault types, x and If none of the above-mentioned flat cable (1) short circuit criteria are met, then it is determined that there is no short circuit fault; The specific expression is as follows: A short circuit occurs between phase m conductor and phase m shielding layer, where m represents phases A, B, and C. Assume the transition resistance is... : m represents phase A: ； m is phase B: ； m is phase C: ； The m-phase conductor and the m-phase shielding layer are short-circuited to ground. Let m represent phases A, B, and C. Assume the transition resistance between the m-phase conductor and the m-phase shielding layer is... The transition resistance of the m-phase shielding layer to ground is : m represents phase A: ； m is phase B: ； m is phase C: ； The B-phase conductor (5), B-phase shielding layer (51), n-phase shielding layer, and n-phase conductor are short-circuited, where n represents phases A and C. Assume the transition resistance between the B-phase conductor (5) and the B-phase shielding layer (51) is... The transition resistance between phase B shielding layer (51) and phase n shielding layer is The transition resistance between the n-phase conductor and the n-phase shielding layer is : n represents phase A: ； ； n represents phase C: ； ； Short circuit in C-phase conductor (6), C-phase shielding layer (61) and power core (7): Let the transition resistance between the C-phase conductor (6) and the C-phase shielding layer (61) be... The transition resistance between the C-phase shielding layer (61) and the power core (7) is : ； ； If the power core (7) or control core (8) is short-circuited to ground, the transition resistance is set to be... : Power core (7) ground short circuit: ； ； Control core (8) ground short circuit: ； ； The power core (7) and the control core (8) are short-circuited. Assume the transition resistance between the power core (7) and the control core (8) is... : ； ； The power core (7) and the control core (8) are short-circuited to ground. Assume the transition resistance between the power core (7) and the control core (8) is... The transition resistance to ground is : ； 。

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