Line fault type identification method

Abstract

The invention provides a line fault type identification method, which comprises overload tripping, typical short circuit tripping and heavy load and large load input / long-distance short circuit tripping, and comprises the following steps: S1, collecting and storing current waveform maximum absolute value data of 10 cycles before tripping; calculating the current change slope K of the adjacent cycles according to a formula * * K = (II) / (tt) * *; the judgment conditions are that the circuit breaker trips, and the change slope K of all adjacent waveform currents is less than Kset1. According to the line fault type identification method provided by the invention, four tripping types of overload, typical short circuit, heavy load and heavy load input and long-distance short circuit can be rapidly identified, manual test transmission judgment is not needed, the identification speed is high, the accuracy rate is high, operation and maintenance personnel can be guided to rapidly dispose, the power failure time is greatly shortened, and the power supply reliability of a low-voltage distribution network is improved.

Description

Technical Field

[0001] This invention relates to the field of fault detection in low-voltage distribution networks, and more particularly to a method for identifying line fault types. Background Technology

[0002] Low-voltage distribution networks are the "last mile" of the power system facing end users, undertaking the functions of power distribution, metering and monitoring, and safety protection.

[0003] Currently, when a low-voltage distribution network trips, ordinary mechanical switches do not record current and voltage data, making it impossible to directly determine the cause of the trip. Manual reconnection and testing rely solely on experience, which is inefficient and inaccurate. It is also impossible to quickly distinguish between overload tripping, short-circuit fault tripping, heavy load tripping, and long-distance short-circuit tripping, which can lead to long troubleshooting times and slow power restoration, seriously affecting users' electricity experience and power supply reliability.

[0004] Therefore, it is necessary to provide a method for identifying line fault types to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a method for identifying line fault types, which solves the problems of not being able to quickly and accurately identify fault types after a low-voltage distribution network trips, and the low efficiency and poor accuracy of manual judgment.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for identifying line fault types, comprising:

[0007] Overload tripping, typical short-circuit tripping, and tripping due to heavy load and large load input / long-distance short circuit;

[0008] The overload tripping includes the following steps:

[0009] S1. Collect and store the maximum absolute value data of the current waveform for the 10 cycles before the trip;

[0010] S2. Calculate the slope K of the current change between adjacent cycles using the formula **K=(I2−I1) / (t2−t1)**.

[0011] S3. Judgment condition: The circuit breaker trips, and the slope of the current change of all adjacent waveforms K < Kset1;

[0012] S4. Identification conclusion: It is determined that the overload caused the overcurrent, resulting in the circuit breaker overcurrent protection tripping;

[0013] The typical short-circuit trip includes the following steps:

[0014] S1. Collect and store the maximum absolute value data of the current waveform for the 10 cycles before the trip;

[0015] S2. Calculate the slope K of the current change between adjacent cycles using the formula **K=(I2−I1) / (t2−t1)**.

[0016] S3. Judgment condition: The circuit breaker trips, and the slope of the current change of any adjacent waveform is K > Kset2;

[0017] S4. Identification conclusion: It is determined that the short circuit fault caused a sudden change in current, resulting in the circuit breaker overcurrent protection tripping.

[0018] The tripping of a circuit breaker under heavy load and large load input / long-distance short circuit includes the following steps:

[0019] S1. Collect and store the current and voltage waveforms and phasor data for the 10 cycles before the trip, and calculate the slope K of the current change between adjacent cycles.

[0020] S2. Initial screening of slope: If Kset1 < K < Kset2 is satisfied, proceed to the precise impedance angle differentiation process.

[0021] S3, Phasor Calculation;

[0022] S4. Impedance angle determination.

[0023] Preferably, Kset1 is the high-load characteristic slope, and Kset2 is the short-circuit characteristic slope.

[0024] Preferably, the phasor calculation includes the following scenarios: high load input scenario: fault current phasor Calculate the impedance angle φ = arg( );

[0025] Long-distance short circuit scenario: fault current phasor Calculate the impedance angle φ = arg( ).

[0026] Preferably, the impedance angle determination includes the following determination: if φ > 45°: fault biased inductance, determined as a heavy load trip under heavy load;

[0027] If φ < 45°: fault bias resistance, determined to be a long-distance short-circuit fault trip.

[0028] Preferably, the overload tripping involves the use of low-voltage distribution network equipment, which includes a distribution cabinet body, a heat dissipation component, two moving components, and a protective component. The heat dissipation component is located on the back of the distribution cabinet body, the two moving components are respectively located on the upper and lower sides of the back of the distribution cabinet body, and the protective component is located between the two moving components.

[0029] Preferably, the heat dissipation assembly includes a heat dissipation mesh, multiple positioning blocks, multiple positioning slots, and multiple bolts. The multiple positioning blocks are respectively connected to the left and right sides of the top and bottom of the heat dissipation mesh, the multiple positioning slots are respectively opened on the surface of the main body of the power distribution cabinet, and the multiple bolts are respectively disposed between the multiple positioning blocks and the main body of the power distribution cabinet.

[0030] Preferably, the movable component includes a fixed rod, a partition block, two movable sleeves, and two connecting brackets. The partition block is connected to the center of the surface of the fixed rod, the two movable sleeves are respectively fitted onto the surface of the fixed rod and to the left and right sides of the partition block, and the two connecting brackets are respectively connected to the bottom of the two movable sleeves.

[0031] Preferably, the protective assembly includes two protective plates and two magnetic blocks, with the two protective plates respectively connected to the bottom of the two connecting brackets, and the two magnetic blocks respectively connected to opposite sides of the two protective plates.

[0032] Preferably, an installation assembly is provided between the fixing rod and the main body of the distribution cabinet. The installation assembly includes a mounting ring, a mounting base and two threaded bolts. The mounting ring is connected to the surface of the fixing rod and the mounting base is connected to the bottom of the mounting ring.

[0033] Preferably, both threaded bolts are disposed between the mounting base and the main body of the distribution cabinet.

[0034] Compared with related technologies, the line fault type identification method provided by the present invention has the following beneficial effects:

[0035] This invention provides a method for identifying line fault types, which can quickly identify four types of tripping: overload, typical short circuit, heavy load input, and long-distance short circuit. It eliminates the need for manual testing and judgment, and features fast identification speed and high accuracy. It can guide maintenance personnel to quickly handle the situation, significantly shorten power outage time, and improve the reliability of low-voltage distribution network power supply. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a first embodiment of a line fault type identification method provided by the present invention;

[0037] Figure 2 This is a schematic diagram of the change in current;

[0038] Figure 3 The first schematic diagram is for overload tripping;

[0039] Figure 4 The second schematic diagram shows a tripping circuit breaker due to overload.

[0040] Figure 5This is a first schematic diagram of a typical short-circuit trip;

[0041] Figure 6 This is a second schematic diagram of a typical short-circuit trip;

[0042] Figure 7 A schematic diagram of tripping due to heavy load and large load input / long-distance short circuit;

[0043] Figure 8 This is a schematic diagram showing that the voltage of a large motor far exceeds the current when it starts up.

[0044] Figure 9 for A schematic diagram of polar coordinates;

[0045] Figure 10 This is a schematic diagram showing that the voltage slightly leads the current during a short-circuit fault.

[0046] Figure 11 for A schematic diagram of polar coordinates;

[0047] Figure 12 This is a schematic diagram showing a slight lead between line voltage and current.

[0048] Figure 13 for A schematic diagram of polar coordinates;

[0049] Figure 14 This is a schematic diagram of the polar coordinates of the current during the startup of a large motor.

[0050] Figure 15 This is a schematic diagram of the polar coordinates of the current during a short-circuit fault.

[0051] Figure 16 This is a schematic diagram of the structure of a second embodiment of a line fault type identification method provided by the present invention;

[0052] Figure 17 for Figure 16 The enlarged schematic diagram of part A shown below;

[0053] Figure 18 for Figure 16 A schematic diagram of the three-dimensional structure of the power distribution cabinet shown;

[0054] Figure 19 for Figure 18 The enlarged schematic diagram of section B is shown below;

[0055] Figure 20 for Figure 16 A schematic diagram of the external three-dimensional structure of the distribution cabinet shown;

[0056] Figure 21A schematic diagram of the structure of a third embodiment of a line fault type identification method provided by the present invention;

[0057] Figure 22 for Figure 21 The enlarged schematic diagram of section C is shown.

[0058] Numbered in the diagram: 1. Main body of the power distribution cabinet.

[0059] 2. Heat dissipation assembly; 21. Heat dissipation mesh; 22. Positioning block; 23. Positioning groove; 24. Bolt.

[0060] 3. Moving component; 31. Fixed rod; 32. Divider block; 33. Moving sleeve; 34. Connecting bracket.

[0061] 4. Protective components, 41. Protective plate, 42. Magnetic block,

[0062] 5. Mounting components, 51. Mounting ring, 52. Mounting base, 53. Threaded bolt. Detailed Implementation

[0063] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0064] First Embodiment

[0065] Please refer to the following: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 , Figure 13 , Figure 14 and Figure 15 ,in, Figure 1 This is a schematic diagram of the structure of a first embodiment of a line fault type identification method provided by the present invention; Figure 2 This is a schematic diagram of the change in current; Figure 3 The first schematic diagram is for overload tripping; Figure 4 The second schematic diagram shows a tripping circuit breaker due to overload. Figure 5 This is a first schematic diagram of a typical short-circuit trip; Figure 6 This is a second schematic diagram of a typical short-circuit trip; Figure 7 A schematic diagram of tripping due to heavy load and large load input / long-distance short circuit; Figure 8 This is a schematic diagram showing that the voltage of a large motor far exceeds the current when it starts up. Figure 9 for A schematic diagram of polar coordinates; Figure 10This is a schematic diagram showing that the voltage slightly leads the current during a short-circuit fault. Figure 11 for A schematic diagram of polar coordinates; Figure 12 This is a schematic diagram showing a slight lead between line voltage and current. Figure 13 for A schematic diagram of polar coordinates; Figure 14 This is a schematic diagram of the polar coordinates of the current during the startup of a large motor. Figure 15 This is a schematic diagram of the current in polar coordinates during a short-circuit fault. A method for identifying line fault types includes:

[0066] Overload tripping, typical short-circuit tripping, and tripping due to heavy load and large load input / long-distance short circuit;

[0067] The overload tripping includes the following steps:

[0068] S1. Collect and store the maximum absolute value data of the current waveform for the 10 cycles before the trip;

[0069] S2. Calculate the slope K of the current change between adjacent cycles using the formula **K=(I2−I1) / (t2−t1)**.

[0070] S3. Judgment condition: The circuit breaker trips, and the slope of the current change of all adjacent waveforms K < Kset1;

[0071] S4. Identification conclusion: It is determined that the overload caused the overcurrent, resulting in the circuit breaker overcurrent protection tripping;

[0072] The typical short-circuit trip includes the following steps:

[0073] S1. Collect and store the maximum absolute value data of the current waveform for the 10 cycles before the trip;

[0074] S2. Calculate the slope K of the current change between adjacent cycles using the formula **K=(I2−I1) / (t2−t1)**.

[0075] S3. Judgment condition: The circuit breaker trips, and the slope of the current change of any adjacent waveform is K > Kset2;

[0076] S4. Identification conclusion: It is determined that the short circuit fault caused a sudden change in current, resulting in the circuit breaker overcurrent protection tripping.

[0077] The tripping of a circuit breaker under heavy load and large load input / long-distance short circuit includes the following steps:

[0078] S1. Collect and store the current and voltage waveforms and phasor data for the 10 cycles before the trip, and calculate the slope K of the current change between adjacent cycles.

[0079] S2. Initial screening of slope: If Kset1 < K < Kset2 is satisfied, proceed to the precise impedance angle differentiation process.

[0080] S3, Phasor Calculation;

[0081] S4. Impedance angle determination.

[0082] Kset1 is the slope of the high load characteristic, and Kset2 is the slope of the short circuit characteristic.

[0083] The phasor calculation includes the following scenarios: High load input scenario: Fault current phasor Calculate the impedance angle φ = arg( );

[0084] Long-distance short circuit scenario: fault current phasor Calculate the impedance angle φ = arg( ).

[0085] The impedance angle determination includes the following determination: if φ > 45°: fault biased inductance, determined to be a tripping under heavy load;

[0086] If φ < 45°: fault bias resistance, determined to be a long-distance short-circuit fault trip.

[0087] Collect and store the maximum absolute value data of the current waveform for the 10 cycles before the trip for subsequent calculation of the current change slope and judgment of the load change trend.

[0088] K reflects the rate of change of current and is used to distinguish between overload and fault conditions.

[0089] Kset1 is the slope of the high-load characteristic; the current rises slowly under overload conditions without abrupt changes.

[0090] Kset2 is the slope of the short-circuit characteristic, where the current changes drastically and instantaneously during a short circuit.

[0091] The starting behavior of a large motor is strongly inductive (φ≈80°), while the behavior during a long-distance short circuit is resistive (φ≈26.6°), with a clear distinction between the two.

[0092] The working principle of the line fault type identification method provided by this invention is as follows:

[0093] By collecting current and voltage data for the 10 cycles prior to the trip, the overload trip and typical short-circuit trip are quickly distinguished by the current change slope K. For ambiguous cases where the slope is between the two, the impedance angle is further calculated by the fault current phasor. Based on the inductive / resistive characteristics, the trip caused by heavy load and the trip caused by long-distance short circuit are accurately distinguished. Finally, the automatic, rapid and accurate identification of the four types of trip causes is achieved.

[0094] Compared with related technologies, the line fault type identification method provided by the present invention has the following beneficial effects:

[0095] This invention provides a method for identifying line fault types, which can quickly identify four types of tripping: overload, typical short circuit, heavy load input, and long-distance short circuit. It eliminates the need for manual testing and judgment, and features fast identification speed and high accuracy. It can guide maintenance personnel to quickly handle the situation, significantly shorten power outage time, and improve the reliability of low-voltage distribution network power supply.

[0096] Second Embodiment

[0097] Please refer to the following: Figure 16 , Figure 17 , Figure 18 , Figure 19 and Figure 20 Based on the line fault type identification method provided in the first embodiment of this application, the second embodiment of this application proposes another line fault type identification method. The second embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the separate implementation of the first embodiment.

[0098] Specifically, the difference in the line fault type identification method provided in the second embodiment of this application is that the overload tripping will use low-voltage distribution network equipment. The low-voltage distribution network equipment includes a distribution cabinet body 1, a heat dissipation component 2, two moving components 3 and a protective component 4. The heat dissipation component 2 is disposed on the back of the distribution cabinet body 1, the two moving components 3 are respectively disposed on the upper and lower sides of the back of the distribution cabinet body 1, and the protective component 4 is disposed between the two moving components 3.

[0099] The heat dissipation assembly 2 includes a heat dissipation mesh 21, multiple positioning blocks 22, multiple positioning grooves 23, and multiple bolts 24. The multiple positioning blocks 22 are respectively connected to the left and right sides of the top and bottom of the heat dissipation mesh 21. The multiple positioning grooves 23 are respectively opened on the surface of the power distribution cabinet body 1. The multiple bolts 24 are respectively disposed between the multiple positioning blocks 22 and the power distribution cabinet body 1.

[0100] The use of multiple positioning blocks 22 and multiple positioning slots 23 can facilitate the positioning of the heat dissipation mesh 21 during installation. When disassembling and cleaning the heat dissipation mesh 21, first remove the bolts 24 between the multiple positioning blocks 22 and the main body 1 of the power distribution cabinet. After the multiple bolts 24 are removed, pull the heat dissipation mesh 21 to move it outward. When the heat dissipation mesh 21 moves outward, it will cause the multiple positioning blocks 22 to separate from the main body 1 of the power distribution cabinet.

[0101] The movable component 3 includes a fixed rod 31, a partition block 32, two movable sleeves 33 and two connecting brackets 34. The partition block 32 is connected to the center of the surface of the fixed rod 31. The two movable sleeves 33 are respectively fitted onto the surface of the fixed rod 31 and are connected to the left and right sides of the partition block 32. The two connecting brackets 34 are respectively connected to the bottom of the two movable sleeves 33.

[0102] The protective assembly 4 includes two protective plates 41 and two magnetic blocks 42. The two protective plates 41 are respectively connected to the bottom of the two connecting brackets 34, and the two magnetic blocks 42 are respectively connected to the opposite side of the two protective plates 41.

[0103] The use of the fixed rod 31 and the two movable sleeves 33 can open and close the two protective components 4. When operating the two protective plates 41, the two protective plates 41 are first moved by pulling them. When the protective plates 41 move, the movable sleeves 33 are driven to move left and right on the fixed rod 31 through the connecting bracket 34.

[0104] Compared with related technologies, the line fault type identification method provided by the present invention has the following beneficial effects:

[0105] This invention provides a method for identifying line fault types. A heat dissipation component 2 is installed on the back of the main body 1 of the distribution cabinet, which allows the heat generated by the components inside the main body 1 working for a long time to flow rapidly to the outside of the main body 1.

[0106] Third Embodiment

[0107] Please refer to the following: Figure 21 and Figure 22 Based on the line fault type identification method provided in the first embodiment of this application, the third embodiment of this application proposes another line fault type identification method. The third embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the third embodiment will not affect the separate implementation of the first embodiment.

[0108] Specifically, the difference in the method for identifying line fault types provided in the third embodiment of this application is that it also includes an installation component 5. The installation component 5 is disposed between the fixing rod 31 and the main body 1 of the distribution cabinet. The installation component 5 includes an installation ring 51, an installation seat 52 and two threaded connecting bolts 53. The installation ring 51 is connected to the surface of the fixing rod 31 and the installation seat 52 is connected to the bottom of the installation ring 51.

[0109] Both threaded bolts 53 are disposed between the mounting base 52 and the main body 1 of the power distribution cabinet.

[0110] A threaded hole adapted to the threaded bolt 53 is provided between the mounting base 52 and the main body of the distribution cabinet 1.

[0111] The working principle of the line fault type identification method provided by this invention is as follows:

[0112] When using the device, to fix the fixing rod 31 to the main body 1 of the distribution cabinet, first attach the fixing rod 31 to the surface of the main body 1 of the distribution cabinet through the mounting base 52, and then use multiple threaded bolts 53 to pass through the mounting base 52 and thread them to the main body 1 of the distribution cabinet.

[0113] Compared with related technologies, the line fault type identification method provided by the present invention has the following beneficial effects:

[0114] The present invention provides a method for identifying line fault types. The mounting ring 51 with mounting base 52 and multiple threaded bolts 53 on the surface of the fixing rod 31 can facilitate the installation of the fixing rod 31 and the main body of the distribution cabinet 1.

[0115] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for identifying line fault types, characterized in that, include: Overload tripping, typical short-circuit tripping, and tripping due to heavy load and large load input / long-distance short circuit; The overload tripping includes the following steps: S1. Collect and store the maximum absolute value data of the current waveform for the 10 cycles before the trip; S2. Calculate the slope K of the current change between adjacent cycles using the formula **K=(I2−I1) / (t2−t1)**. S3. Judgment condition: The circuit breaker trips, and the slope of the current change of all adjacent waveforms K < Kset1; S4. Identification conclusion: It is determined that the overload caused the overcurrent, resulting in the circuit breaker overcurrent protection tripping; The typical short-circuit trip includes the following steps: S1. Collect and store the maximum absolute value data of the current waveform for the 10 cycles before the trip; S2. Calculate the slope K of the current change between adjacent cycles using the formula **K=(I2−I1) / (t2−t1)**. S3. Judgment condition: The circuit breaker trips, and the slope of the current change of any adjacent waveform is K > Kset2; S4. Identification conclusion: It is determined that the short circuit fault caused a sudden change in current, resulting in the circuit breaker overcurrent protection tripping. The tripping of a circuit breaker under heavy load and large load input / long-distance short circuit includes the following steps: S1. Collect and store the current and voltage waveforms and phasor data for the 10 cycles before the trip, and calculate the slope K of the current change between adjacent cycles. S2. Initial screening of slope: If Kset1 < K < Kset2 is satisfied, proceed to the precise impedance angle differentiation process. S3, Phasor Calculation; S4. Impedance angle determination.

2. The line fault type identification method according to claim 1, characterized in that, Kset1 is the slope of the high load characteristic, and Kset2 is the slope of the short circuit characteristic.

3. The line fault type identification method according to claim 1, characterized in that, The phasor calculations include the following scenarios: High load application scenario: Fault current phasor Calculate the impedance angle φ = arg( ); Long-distance short circuit scenario: fault current phasor Calculate the impedance angle φ = arg( ).

4. The line fault type identification method according to claim 1, characterized in that, The impedance angle determination includes the following determination: if φ > 45°: fault biased inductance, determined to be a tripping under heavy load; If φ < 45°: fault bias resistance, determined to be a long-distance short-circuit fault trip.

5. The line fault type identification method according to claim 1, characterized in that, The overload tripping will utilize low-voltage distribution network equipment, which includes a distribution cabinet body, a heat dissipation component, two moving components, and a protective component. The heat dissipation component is located on the back of the distribution cabinet body, the two moving components are respectively located on the upper and lower sides of the back of the distribution cabinet body, and the protective component is located between the two moving components.

6. The line fault type identification method according to claim 5, characterized in that, The heat dissipation assembly includes a heat dissipation mesh, multiple positioning blocks, multiple positioning slots, and multiple bolts. The multiple positioning blocks are respectively connected to the left and right sides of the top and bottom of the heat dissipation mesh. The multiple positioning slots are respectively opened on the surface of the main body of the power distribution cabinet. The multiple bolts are respectively disposed between the multiple positioning blocks and the main body of the power distribution cabinet.

7. The line fault type identification method according to claim 5, characterized in that, The movable component includes a fixed rod, a partition block, two movable sleeves, and two connecting brackets. The partition block is connected to the center of the surface of the fixed rod. The two movable sleeves are respectively fitted onto the surface of the fixed rod and to the left and right sides of the partition block. The two connecting brackets are respectively connected to the bottom of the two movable sleeves.

8. The line fault type identification method according to claim 5, characterized in that, The protective assembly includes two protective plates and two magnetic blocks. The two protective plates are respectively connected to the bottom of the two connecting brackets, and the two magnetic blocks are respectively connected to the opposite side of the two protective plates.

9. The line fault type identification method according to claim 5, characterized in that, An installation assembly is provided between the fixing rod and the main body of the distribution cabinet. The installation assembly includes a mounting ring, a mounting base, and two threaded bolts. The mounting ring is connected to the surface of the fixing rod, and the mounting base is connected to the bottom of the mounting ring.

10. The line fault type identification method according to claim 9, characterized in that, Both threaded bolts are located between the mounting base and the main body of the distribution cabinet.

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