Flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification

Abstract

The invention belongs to the technical field of flat cable fault detection, and particularly relates to a flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification, which comprises the following steps: acquiring time domain data and electrical parameters of voltage and current at two ends of a flat cable; listing a relation equation of the electrical quantities of the two ends of the flat cable according to two conditions of cracking and short circuit; substituting the time domain data of the voltage and the current into the equation; the fault type is judged according to the rule provided by the invention. According to the method, the fault type and the transition resistance of the cracked conductor with the cracking fault or the short-circuit fault can be rapidly and reliably identified, and the method is not influenced by a power supply and a load theoretically, and has a relatively high application value.

Description

Technical Field

[0001] The invention belongs to the technical field of flat cable fault detection, and in particular relates to a flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification. Background Art

[0002] Flat cables are flat cables that are usually used for the transmission of power and communication signals. Compared with traditional round cables, flat cables have higher flexibility and bending resistance, and are often used in buildings, tunnels, subways, ports and other places that have special requirements for flat cable wiring. Flat cables are often exposed to various harsh environmental conditions during use. Long-term use and the influence of the external environment can easily lead to cracking, short circuit and other faults of flat cables. These faults will not only affect the normal operation of the equipment, but may also cause abnormalities in the power system, equipment damage and even safety accidents. Therefore, it is particularly important to identify cracking or short circuit faults of flat cables in a timely and effective manner.

[0003] At present, the fault location methods for flat cables include the fundamental frequency vector method, the traveling wave method, the time domain model method and the artificial intelligence method. Although the fundamental frequency vector method is simple in principle, if the transition resistance varies with time, this method cannot accurately measure the fault distance; the location method based on the traveling wave is not affected by factors such as the transition resistance and the line structure, but the flat cable is usually short in length, which will lead to a complex traveling wave refraction and reflection process, making it difficult to accurately identify the traveling wave head; the artificial intelligence method has accurate distance measurement, but requires a large number of data samples for training, which brings high time and resource costs, and the model depends on a specific environment and data set, and needs to be retrained or adjusted when the environment changes to maintain adaptability; the time domain model method is not affected by high-frequency harmonics, and can still accurately measure the fault distance for time-varying transition resistance faults. However, the time domain model method is currently mainly used for distance measurement of single-core cables, and the flat cable structure is relatively complex, and there are many electrical coupling parameters in its equivalent circuit model, so the existing method cannot be directly transplanted. In addition, the above analysis methods are basically used to identify short-circuit faults, and there is little reference to the cracking faults of flat cables. Therefore, it is of great significance to study the fault identification and distance measurement of flat cables. Summary of the invention

[0004] The technical problem to be solved by the present invention is that in the above-mentioned prior art, the above-mentioned analysis method is basically 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 object, the technical solution adopted by the present invention is:

[0006] A method for flat cable fault identification and distance measurement based on time domain multivariate electrical parameter identification includes the following steps:

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

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

[0009] Step 3: Determine whether it is a cracking fault according to the flat cable cracking criterion;

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

[0011] Step 5: Determine whether it is a short circuit fault according to the flat cable short circuit criterion;

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

[0013] By adopting the above technical solution, the method can quickly and reliably identify cracking or short circuit faults, and can accurately determine the fault conductor, fault distance, fault type and transition resistance. This helps to respond and solve problems quickly, reducing equipment downtime and maintenance costs.

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

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

[0016] Furthermore, the current at both ends and the voltage of the three-phase conductor core, power core, and control core are obtained by measurement, and the shielding layer voltage of each phase at both ends and the grounding core voltage are calculated by the following formula:

[0017]

[0018] By adopting the above technical solution, the processing of large amounts of data can be simplified by organizing the measured voltage and current values ​​into a matrix form. Matrix operations can efficiently manage and calculate these data, reducing the complexity of the algorithm. The use of matrix representation helps to establish a more concise mathematical model to describe the electrical behavior in flat cables. This makes the analysis of electrical relationships in cracking or short circuit conditions more intuitive and easy to understand. Matrix operations allow the use of rich linear algebra tools and techniques.

[0019] Furthermore, the voltage and current at both ends of the tail Forming the voltage and current matrix V at both ends S (t), I S (t), V R (t), I R (t): where

[0020]

[0021]

[0022] Establish the fault resistance matrix R'(t) and inductance matrix L'(t):

[0023] Where R'(t) = diag(R' 11 (t),R' 22 (t),R′ 33 (t),R' 44 (t),R′ 55 (t),R' 66 (t),R' 77 (t),R′ 88 (t),R' 99 (t));

[0024] L'(t)=diag(L' 11 (t),L' 22 (t),L' 33 (t),L' 44 (t),L' 55 (t),L' 66 (t),L' 77 (t),L' 88 (t),L' 99 (t)).

[0025] Furthermore, in step 2 and step 3, the cracking relationship equation of the double-terminal electrical quantity is established according to the lumped parameter model:

[0026]

[0027] Where Δt is the sampling interval.

[0028] By adopting the above technical solution, the lumped parameter model approximates the distributed characteristics of the flat cable (such as resistance, inductance, and capacitance) as lumped components. This greatly simplifies the mathematical model, making the calculation more efficient and easy to implement. Due to the use of the lumped parameter model, it is possible to avoid dealing with complex partial differential equations and instead use relatively simple algebraic equations to describe the system behavior. This is very important for real-time monitoring and fast response. Although it is based on the assumption of lumped parameters, the model is still applicable to flat cables of different lengths and types, as long as the parameter matrices R, L, and C are appropriately adjusted.

[0029] Furthermore, the electrical quantities at the beginning and end of the flat cable are substituted into the fault resistance matrix R'(t) and the inductance matrix L'(t), and the solution is obtained. The elements at the corresponding positions of the obtained R'(t) and L'(t) are substituted into the following flat cable cracking criterion to determine whether a cracking fault occurs, which specifically includes the following steps:

[0030] Step 21: If j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)≥mlR(j,j) and L' jj (t)≥mlL(j,j) holds true, then it is determined that a crack fault occurs in the j-th phase, where R(j,j) and L(j,j) are the elements at the j-th row and j-th column of the unit resistance matrix R and the inductance matrix L, respectively, and m is the reliability coefficient, which is used to adjust the sensitivity of the criterion to ensure the accuracy of fault identification;

[0031] Step 22: For any j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)<mlR(j,j) or L' jj (t)<mlL(j,j) holds true, and the fault conductance matrix Y(t) containing unknowns is defined.

[0032] By adopting the above technical solution, by calculating the R'(t) and L'(t) matrix elements and substituting them into the given criteria, it is possible to determine very accurately which phase has cracked. This accuracy is crucial for rapid repair and reduced downtime. Steps 21 and 22 provide a set of clear logical rules for determining the type of fault.

[0033] Furthermore, in step 4 and step 5, the short-circuit condition relationship equation of the two-terminal electrical quantity is established according to the lumped parameter model:

[0034]

[0035] Where x is the fault distance, V f (t) is the voltage matrix at the fault point;

[0036] V f The specific expression of (t) is as follows:

[0037]

[0038] Substitute the voltage and current matrices at the beginning and end and solve for x and Y(t).

[0039] By adopting the above technical solution, through mathematical modeling and numerical solution, the specific location of the short circuit fault can be determined very accurately. This high-precision fault location capability is crucial for rapid repair and can significantly reduce troubleshooting time and maintenance costs. This method is not only suitable for simple short circuits between the conductor and the shield, but can also handle more complex fault modes, which increases the versatility and adaptability of the system, enabling it to cope with various possible fault scenarios. The relationship equation based on the concentrated parameter model can be directly calculated using existing electrical measurement data without the need for additional physical testing or disassembly of the equipment.

[0040] Furthermore, the elements of x and Y(t) obtained by solving are substituted into the flat cable short circuit criterion to determine whether a short circuit fault occurs:

[0041] Step 31: For any short-circuit fault type, 0≤x≤l and R fk (t)≥0 holds true, k∈{1,2,3}, then it is determined to be a short circuit fault, and the fault conductor, fault distance, fault type and transition resistance are determined;

[0042] Step 32: For all short-circuit fault types, x and R fk (t) If the above flat cable short-circuit criterion is not met, it is determined that there is no short-circuit fault.

[0043] By adopting the above technical solution, by verifying the specific conditions of different types of short-circuit faults, the fault types can be classified more finely. This helps to take targeted repair measures and improve maintenance efficiency. Step 32 ensures that if all possible short-circuit fault types do not meet the short-circuit criterion, it can be clearly determined that there is no short-circuit fault, reducing the possibility of false alarms. The calculation results are compared with the actual measurement data, and the fault hypothesis is verified by the short-circuit criterion, which improves the credibility of the diagnosis results. Strict short-circuit criterion checks can effectively avoid misjudgments caused by numerical errors or other factors, and enhance the reliability of the system. By solving x, the physical location of the fault can be accurately determined, allowing maintenance personnel to quickly arrive at the site and implement repairs.

[0044] Furthermore, the specific expression of Y(t) is as follows:

[0045] The m-phase conductor and the m-phase shield are short-circuited, m is phase A, phase B, and phase C, and the transition resistance is Rf1 (t):

[0046] m is phase A:

[0047]

[0048] m is the B phase:

[0049]

[0050] m is C phase:

[0051]

[0052] The m-phase conductor and the m-phase shielding layer are short-circuited to the ground. m is phase A, phase B, and phase C. Assume that the transition resistance between the m-phase conductor and the m-phase shielding layer is R f1 (t), the transition resistance of the m-phase shielding layer to the ground is R f2 (t):

[0053] m is phase A:

[0054]

[0055] m is the B phase:

[0056]

[0057] m is C phase:

[0058]

[0059] The B-phase conductor, B-phase shield, n-phase shield and n-phase conductor are short-circuited, n is A-phase and C-phase, and the transition resistance between the B-phase conductor and the B-phase shield is R f1 (t), the transition resistance between the B-phase shielding layer and the n-phase shielding layer is R f2 (t), the transition resistance between the n-phase conductor core and the n-phase shielding layer is R f3 (t):

[0060] n is phase A:

[0061]

[0062] n is C phase:

[0063]

[0064] The C-phase conductor, C-phase shield and power core are short-circuited:

[0065] Assume the transition resistance between the C-phase conductor and the C-phase shield is R f1 (t), the transition resistance between the C-phase shielding layer and the power core is R f2 (t):

[0066]

[0067] The power core or control core is short-circuited to ground, and the transition resistance is R f1 (t):

[0068] Power core ground short circuit:

[0069]

[0070] Control core ground short circuit:

[0071]

[0072] The power core and the control core are short-circuited. Assume that the transition resistance between the power core and the control core is R f1 (t):

[0073]

[0074] The power core and the control core are short-circuited to the ground. Assume that the transition resistance between the power core and the control core is R f1 (t), the transition resistance to ground is R f2 (t):

[0075]

[0076] 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 takes into account the specific transition resistance value, 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 layers and other auxiliary lines, these expressions can effectively handle complex short-circuit situations.

[0077] The beneficial effects of the present invention are:

[0078] 1. The present invention can judge the fault type according to the given rules and can quickly and reliably identify the cracked conductor of the crack fault or the fault type and transition resistance of the short circuit fault, which is not affected by the power supply and load and has high application value;

[0079] 2. The present invention introduces a method based on time-domain multivariate electrical parameter identification, combines the lumped parameter model to establish the relationship equation under cracking and short circuit conditions, and uses strict criteria to make fault judgments. This method can not only accurately locate the fault location (including the fault conductor and fault distance), but also accurately identify the fault type (such as cracking or short circuit) and its transition resistance, thereby improving the speed and accuracy of fault diagnosis, reducing troubleshooting time and maintenance costs, and ensuring the efficient operation of the power system;

[0080] 3. The present 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, the safety and reliability of the system are enhanced. Accurate fault classification helps to take targeted repair measures, reduce unnecessary maintenance work, extend the life of the flat cable, and indirectly reduce the cost of replacing a new flat cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 It is a flow chart of the present invention;

[0082] Figure 2 This is a schematic diagram of the cracking fault of the A-phase shielding layer of the flat cable;

[0083] Figure 3 This is a schematic diagram of a flat cable short circuit failure.

[0084] Among them, 1-flat cable; 2-A phase shielding layer; 3-A phase conductor core; 4-insulating layer; 5-B phase conductor core; 51-B phase shielding layer; 6-C phase conductor core; 61-C phase shielding layer; 7-power core; 8-control core; 9-grounding core; 10-outer sheath. DETAILED DESCRIPTION

[0085] The present invention will be further described below in conjunction with the accompanying drawings.

[0086] like Figure 1 , Figure 2 and Figure 3 As shown, a method for flat cable 1 fault identification and ranging based on time domain multivariate electrical parameter identification includes the following steps:

[0087] Step 1: Obtain the time domain data and electrical parameters of the voltage and current at both ends of the flat cable;

[0088] Step 2: Establish the cracking relationship equation of the electrical quantities at both ends of the flat cable;

[0089] Step 3: Determine whether it is a cracking fault according to the flat cable cracking criterion;

[0090] Step 4: Establish the short-circuit relationship equation of the electrical quantities at both ends of the flat cable;

[0091] Step 5: Determine whether it is a short circuit fault according to the flat cable short circuit criterion;

[0092] Step 6: Determine the fault conductor, fault distance, fault type and transition resistance based on the short circuit situation.

[0093] First, obtain the voltage and current at both ends of flat cable 1 Wherein, i=A, SA, B, SB, C, SC, D, E, F, respectively represent A phase conductor core 3, A phase shielding layer 2, B phase conductor core 5, B phase shielding layer 51, C phase conductor core 6, C phase shielding layer 61, power core 7, control core 8, grounding core 9, Respectively represent the i-phase voltage and current at the first end of flat cable 1, Represent the i-phase voltage and current at the end of flat cable 1. Get the grounding wire resistance R of flat cable 1 g , unit resistance matrix R, unit inductance matrix L and unit capacitance matrix C, and length l of flat cable 1;

[0094] The outermost layers of the flat cable 1 , the A-phase conductor core 3 , the A-phase shielding layer 2 , the B-phase conductor core 5 , the B-phase shielding layer 51 , the C-phase conductor core 6 , the C-phase shielding layer 61 , the power core 7 , the control core 8 and the grounding core 9 are wrapped with an outer sheath 10 .

[0095] (2) Based on the voltage and current at both ends measured in step (1) Forming the voltage and current matrix V at both ends S (t), I S (t), V R (t), I R (t):

[0096]

[0097] (3) Define the fault resistance matrix R'(t) and inductance matrix L'(t) containing unknowns:

[0098] R'(t)=diag(R' 11 (t),R' 22 (t),R′ 33 (t),R' 44 (t),R′ 55 (t),R' 66 (t),R' 77 (t),R′ 88 (t),R' 99 (t))

[0099] L'(t)=diag(L' 11 (t),L' 22 (t),L'33 (t),L' 44 (t),L' 55 (t),L' 66 (t),L' 77 (t),L' 88 (t),L' 99 (t))

[0100] (4) Based on the lumped parameter model, the cracking relationship equation of the double-terminal electrical quantity is established:

[0101]

[0102] Where Δt is the sampling interval.

[0103] (5) Based on the relationship equation described in step (4), substitute the voltage and current matrices at the first and last ends and solve for R'(t) and L'(t).

[0104] (6) Substitute the elements at the corresponding positions of R'(t) and L'(t) obtained in step (5) into the following criterion to determine whether a cracking failure occurs:

[0105] (a) If there exists j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)≥mlR(j,j) and L' jj If (t)≥mlL(j,j) holds, it is determined that a crack fault has occurred in the j-th phase, wherein R(j,j) and L(j,j) are the elements at the j-th row and j-th column of the unit resistance matrix R and the inductance matrix L, respectively, and m is a reliability coefficient used to adjust the sensitivity of the criterion to ensure the accuracy of fault identification. In this embodiment, m=5%.

[0106] (b) If for any j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)<mlR(j,j) or L' jj (t)<mlL(j,j) holds true, go to step (7).

[0107] (7) Define the fault conductance matrix Y(t) containing unknowns. The specific expression of Y(t) is as follows:

[0108] ① The m-phase conductor and the m-phase shield are short-circuited, m is A, B, C, and the transition resistance is R f1 (t):

[0109] m is phase A:

[0110]

[0111] m is the B phase:

[0112]

[0113] m is C phase:

[0114]

[0115] ② The m-phase conductor and the m-phase shielding layer are short-circuited to ground, m is A, B, C, and the transition resistance between the m-phase conductor and the m-phase shielding layer is R f1 (t), the transition resistance of the m-phase shielding layer to the ground is R f2 (t):

[0116] m is phase A:

[0117]

[0118] m is the B phase:

[0119]

[0120] m is C phase:

[0121]

[0122] ③ The B-phase conductor 5, the B-phase shielding layer 51, the n-phase shielding layer and the n-phase conductor are short-circuited, n is the A phase and the C phase, and the transition resistance between the B-phase conductor 5 and the B-phase shielding layer 51 is R f1 (t), the transition resistance between the B-phase shielding layer 51 and the n-phase shielding layer is R f2 (t), the transition resistance between the n-phase conductor core and the n-phase shielding layer is R f3 (t):

[0123] n is phase A:

[0124]

[0125] n is C phase:

[0126]

[0127] ④ The C-phase conductor core 6, the C-phase shielding layer 61 and the power core 7 are short-circuited:

[0128] Assume that the transition resistance between the C-phase conductor 6 and the C-phase shielding layer 61 is R f1 (t), the transition resistance between the C-phase shielding layer 61 and the power core 7 is R f2 (t):

[0129]

[0130] ⑤ The power core 7 or the control core 8 is short-circuited to ground, and the transition resistance is R f1 (t):

[0131] Power core 7 is short-circuited to ground:

[0132]

[0133] Control core 8 is short-circuited to ground:

[0134]

[0135] ⑥ The power core 7 and the control core 8 are short-circuited. Assume that the transition resistance between the power core 7 and the control core 8 is R f1 (t):

[0136]

[0137] ⑦ The power core 7 and the control core 8 are short-circuited to the ground. Assume that the transition resistance between the power core 7 and the control core 8 is R f1 (t), the transition resistance to ground is R f2 (t):

[0138]

[0139] (8) Based on the lumped parameter model, the short-circuit relationship equation of the two-terminal electrical quantity is established:

[0140]

[0141] Where x is the fault distance, V f (t) is the voltage matrix at the fault point, V f The specific expression of (t) is as follows:

[0142]

[0143] (9) Based on the relationship equation described in step (8), substitute the voltage and current matrices at the first and last ends and solve for x and Y(t).

[0144] (10) Substitute the elements of x and Y(t) obtained in step (9) into the following criterion to determine whether a short circuit fault occurs:

[0145] (a) If the solution for any short-circuit fault type is 0≤x≤l and R fk (t)≥0 holds, k∈{1,2,3}, then it is determined to be a short circuit fault. According to the established criteria, the fault conductor, fault distance, fault type and transition resistance are determined.

[0146] (b) If the solution for all short-circuit fault types is x and R fk If (t) does not meet the above criteria, it is determined that there is no short-circuit fault.

[0147] The flat cable 1 of the present invention is a schematic diagram of a cracking fault of the A-phase shielding layer. In the schematic diagram, taking the cracking of the A-phase flat cable 1 as an example, the flat cable 1 fault identification and distance measurement method based on time domain multivariate electrical parameter identification of the present invention includes the following steps for cracking fault identification:

[0148] (1) Measure the voltage and current at both ends of flat cable 1 Wherein, i=A, SA, B, SB, C, SC, D, E, F, respectively represent A phase conductor core 3, A phase shielding layer 2, B phase conductor core 5, B phase shielding layer 51, C phase conductor core 6, C phase shielding layer 61, power core 7, control core 8, grounding core 9, Respectively represent the i-phase voltage and current at the first end of flat cable 1, Represent the i-phase voltage and current at the end of flat cable 1, respectively, and obtain the grounding wire resistance R of flat cable 1 g , unit resistance matrix R, unit inductance matrix L and unit capacitance matrix C, and the length l of flat cable 1.

[0149] (2) Based on the voltage and current at both ends measured in step (1) Forming the voltage and current matrix V at both ends S (t), I S (t), V R (t), I R (t):

[0150]

[0151] (3) Define the fault resistance matrix R'(t) and inductance matrix L'(t) containing unknowns:

[0152] R'(t)=diag(R1'1(t),R' 22 (t),R3'3(t),R' 44 (t),R5'5(t),R' 66 (t),R' 77 (t),R8'8(t),R' 99 (t))

[0153] L'(t)=diag(L' 11 (t),L' 22 (t),L' 33 (t),L' 44 (t),L' 55 (t),L' 66 (t),L' 77 (t),L' 88 (t),L' 99 (t))

[0154] (4) Based on the lumped parameter model, the cracking relationship equation between the voltage and current at both ends is established:

[0155]

[0156] Where Δt is the sampling interval.

[0157] (5) Based on the relationship equation described in step (4), substitute the voltage and current matrices at the first and last ends and solve for R'(t) and L'(t).

[0158] (6) Substitute the elements at the corresponding positions of R'(t) and L'(t) obtained in step (5) into the following criterion to determine whether a cracking failure occurs:

[0159] (a) If there exists j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)≥mlR(j,j) and L' jj If (t)≥mlL(j,j) holds, it is determined that a crack fault has occurred in the j-th phase, wherein R(j,j) and L(j,j) are the elements at the j-th row and j-th column of the unit resistance matrix R and the inductance matrix L, respectively, and m is a reliability coefficient used to adjust the sensitivity of the criterion to ensure the accuracy of fault identification. In this embodiment, m=5%.

[0160] (b) If for any j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)<mlR(j,j) or L' jj (t)<mlL(j,j) holds true, go to step (7).

[0161] After the above crack fault identification, if the flat cable 1 line is not cracked, short circuit fault identification is performed. Figure 2 As shown, it is a schematic diagram of a short circuit fault of a flat cable 1 of the present invention. In this schematic diagram, taking the short circuit of the A-phase conductor 3 and the A-phase shielding layer 2 of the flat cable 1 as an example, a method for identifying and ranging the fault of a flat cable 1 based on time domain multivariate electrical parameter identification of the present invention includes the following steps for short circuit fault identification:

[0162] (7) Define the fault conductance matrix Y(t) containing unknowns. The specific expression of Y(t) is as follows:

[0163] ① The m-phase conductor and the m-phase shield are short-circuited, m is phase A, phase B, and phase C, and the transition resistance is R f1 (t):

[0164] m is phase A:

[0165]

[0166] m is the B phase:

[0167]

[0168] m is C phase:

[0169]

[0170] ② The m-phase conductor and the m-phase shielding layer are short-circuited to ground. m is phase A, phase B, and phase C. Assume that the transition resistance between the m-phase conductor and the m-phase shielding layer is R f1 (t), the transition resistance of the m-phase shielding layer to the ground is R f2 (t):

[0171] m is phase A:

[0172]

[0173] m is the B phase:

[0174]

[0175] m is C phase:

[0176]

[0177] ③ The B-phase conductor 5, the B-phase shielding layer 51, the n-phase shielding layer and the n-phase conductor are short-circuited, n is the A phase and the C phase, and the transition resistance between the B-phase conductor 5 and the B-phase shielding layer 51 is R f1 (t), the transition resistance between the B-phase shielding layer 51 and the n-phase shielding layer is R f2 (t), the transition resistance between the n-phase conductor core and the n-phase shielding layer is R f3 (t):

[0178] n is phase A:

[0179]

[0180] n is C phase:

[0181]

[0182] ④ The C-phase conductor core 6, the C-phase shielding layer 61 and the power core 7 are short-circuited:

[0183] Assume that the transition resistance between the C-phase conductor 6 and the C-phase shielding layer 61 is R f1 (t), the transition resistance between the C-phase shielding layer 61 and the power core 7 is R f2 (t):

[0184]

[0185] ⑤ The power core 7 or the control core 8 is short-circuited to ground, and the transition resistance is Rf1 (t):

[0186] Power core 7 is short-circuited to ground:

[0187]

[0188] Control core 8 is short-circuited to ground:

[0189]

[0190] ⑥ The power core 7 and the control core 8 are short-circuited. Assume that the transition resistance between the power core 7 and the control core 8 is R f1 (t):

[0191]

[0192] ⑦ The power core 7 and the control core 8 are short-circuited to the ground. Assume that the transition resistance between the power core 7 and the control core 8 is R f1 (t), the transition resistance to ground is R f2 (t):

[0193]

[0194] (8) Based on the lumped parameter model, the short-circuit relationship equation between the voltage and current at both ends is established:

[0195]

[0196] Where x is the fault distance, V f (t) is the voltage matrix at the fault point, V f The specific expression of (t) is as follows:

[0197]

[0198] (9) Based on the relationship equation described in step (8), substitute the voltage and current matrices at the first and last ends and solve for x and Y(t).

[0199] (10) Substitute the elements of x and Y(t) obtained in step (9) into the following criterion to determine whether a short circuit fault occurs:

[0200] (a) If the solution for any short-circuit fault type is 0≤x≤l and R fk (t)≥0 holds, k∈{1,2,3}, then it is determined to be a short circuit fault. According to the established criteria, the fault conductor, fault distance, fault type and transition resistance are determined.

[0201] (b) If the solution for all short-circuit fault types is x and R fk If (t)≥0 does not meet the above criteria, it is determined that there is no short-circuit fault.

[0202] The above process of the present invention is also applicable to cracks in the A phase, B phase, B phase shielding layer 51, C phase, C phase shielding layer 61, power core 7, control core 8, grounding core 9 of the flat cable 1, as well as the other 6 types of short circuit faults.

[0203] In order to verify the effectiveness and reliability of the present invention, a simulation model of the flat cable 1 was built on PSCAD / EMTDC, and two fault types, cracking and short circuit, were simulated respectively. The cracking fault identification results are shown in Table 1

[0204]

[0205] Table 1 The short circuit fault identification results are shown in Table 2:

[0206]

[0207]

[0208] Table 2

[0209] The present invention can quickly and reliably identify the fault type and transition resistance size of a cracked conductor or a short circuit fault of a cracking fault. The present invention is theoretically not affected by power supply and load and has high application value.

[0210] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within 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 belong to the protection scope of the present invention.

Claims

1. A method for flat cable fault identification and distance measurement based on time domain multivariate electrical parameter identification, characterized in that: The steps include: Step 1: Obtaining time domain data and electrical parameters of voltage and current at both ends of the flat cable (1); Step 2: Establish the cracking relationship equation of the electrical quantities at both ends of the flat cable (1); Step 3: Determine whether it is a crack fault according to the flat cable (1) crack criterion; Step 4: Establish the short-circuit relationship equation of the electrical quantities at both ends of the flat cable (1); Step 5: Determine whether it is a short circuit fault according to the short circuit criterion of the flat cable (1); Step 6: Determine the fault conductor, fault distance, fault type and transition resistance based on the short circuit situation.

2. The flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification according to claim 1 is characterized in that: In step 1: Obtain the voltage and current at both ends of the flat cable (1) Wherein, i=A, SA, B, SB, C, SC, D, E, F, respectively representing the A-phase conductor core (3), the A-phase shielding layer (2), the B-phase conductor core (5), the B-phase shielding layer (51), the C-phase conductor core (6), the C-phase shielding layer (61), the power core (7), the control core (8), and the grounding core (9), They represent the i-phase voltage and current at the head end of the flat cable (1), Respectively represent the i-phase voltage and current at the end of the flat cable (1); obtain the grounding wire resistance R of the flat cable (1) g , unit resistance matrix R, unit inductance matrix L and unit capacitance matrix C, and the length l of the flat cable (1).

3. The flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification according to claim 2 is characterized in that: The current at both ends and the voltage of the three-phase conductor core, the power core (7) and the control core (8) are obtained by measurement, and the shielding layer voltage of each phase at both ends and the grounding core (9) voltage are calculated by the following formula:

4. The flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification according to claim 3 is characterized in that: Voltage and current at both ends Forming the voltage and current matrix V at both ends S (t), I S (t), V R (t), I R (t): where Establish the fault resistance matrix R'(t) and inductance matrix L'(t): where, R'(t) = diag(R1'1(t), R' 22 (t), R3'3(t), R' 44 (t), R5'5(t), R' 66 (t), R' 77 (t), R8'8(t), R' 99 (t)); L'(t)=diag(L' 11 (t),L' 22 (t),L' 33 (t),L' 44 (t),L' 55 (t),L' 66 (t),L' 77 (t),L' 88 (t),L' 99 (t))。 5. The flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification according to claim 4 is characterized in that: In step 2 and step 3, the cracking relationship equation of the double-terminal electrical quantity is established according to the lumped parameter model: Where Δt is the sampling interval.

6. The method for flat cable fault identification and distance measurement based on time domain multivariate electrical parameter identification according to claim 5, characterized in that: Substitute the voltage and current matrix at both ends of the flat cable (1) into the cracking relationship equation and solve it. Substitute the elements at the corresponding positions of R'(t) and L'(t) obtained by the solution into the following flat cable (1) cracking criterion to determine whether a cracking fault occurs, which specifically includes the following steps: Step 21: If j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)≥mlR(j,j) and L' jj (t)≥mlL(j,j) holds true, then it is determined that a crack fault occurs in the j-th phase, where R(j,j) and L(j,j) are the elements at the j-th row and j-th column of the unit resistance matrix R and the inductance matrix L, respectively, and m is the reliability coefficient, which is used to adjust the sensitivity of the criterion to ensure the accuracy of fault identification; Step 22: For any j∈{1,2,3,4,5,6,7,8,9}, R' jj (t)<mlR(j,j) or L' jj (t)<mlL(j,j) holds true, and the fault conductance matrix Y(t) is established.

7. The flat cable fault identification and distance measurement method based on time domain multivariate electrical parameter identification according to claim 1, characterized in that: In step 4 and step 5, the short-circuit relationship equation of the two-terminal electrical quantity is established according to the lumped parameter model: Where x is the fault distance, V f (t) is the voltage matrix at the fault point; V f The specific expression of (t) is as follows: Substitute the voltage and current matrices at the beginning and end and solve for x and Y(t).

8. The method for flat cable fault identification and distance measurement based on time domain multivariate electrical parameter identification according to claim 7, characterized in that: Substitute the solved elements of x and Y(t) into the short-circuit criterion of the flat cable (1) to determine whether a short-circuit fault occurs: Step 31: For any short-circuit fault type, 0≤x≤l and R fk (t)≥0 holds true, k∈{1,2,3}, then it is determined to be a short circuit fault, and the fault conductor, fault distance, fault type and transition resistance are determined; Step 32: For all short-circuit fault types, x and R fk (t) do not meet the above-mentioned flat cable (1) short-circuit criterion, it is determined that there is no short-circuit fault.

9. The method for flat cable fault identification and distance measurement based on time domain multivariate electrical parameter identification according to claim 7, characterized in that: The specific expression of Y(t) is as follows: The m-phase conductor and the m-phase shield are short-circuited, m is phase A, phase B, and phase C, and the transition resistance is R f1 (t): m is phase A: m is the B phase: m is C phase: The m-phase conductor and the m-phase shielding layer are short-circuited to the ground. m is phase A, phase B, and phase C. Assume that the transition resistance between the m-phase conductor and the m-phase shielding layer is R f1 (t), the transition resistance of the m-phase shielding layer to the ground is R f2 (t): m is phase A: m is the B phase: m is C phase: The B-phase conductor core (5), the B-phase shielding layer (51), the n-phase shielding layer and the n-phase conductor core are short-circuited, n is the A-phase and the C-phase, and the transition resistance between the B-phase conductor core (5) and the B-phase shielding layer (51) is R f1 (t), the transition resistance between the B-phase shielding layer (51) and the n-phase shielding layer is R f2 (t), the transition resistance between the n-phase conductor core and the n-phase shielding layer is R f3 (t): n is phase A: n is C phase: The C-phase conductor core (6), the C-phase shielding layer (61) and the power core (7) are short-circuited: Assume that the transition resistance between the C-phase conductor core (6) and the C-phase shielding layer (61) is R f1 (t), the transition resistance between the C-phase shielding layer (61) and the power core (7) is R f2 (t): The power core (7) or the control core (8) is short-circuited to the ground, and the transition resistance is R f1 (t): Power core (7) short-circuited to ground: Control core (8) is short-circuited to ground: The power core (7) and the control core (8) are short-circuited, and the transition resistance between the power core (7) and the control core (8) is R f1 (t): The power core (7) and the control core (8) are grounded and short-circuited, and the transition resistance between the power core (7) and the control core (8) is R f1 (t), the transition resistance to ground is R f2 (t):

Images