CN-224216802-U - Multi-branch distribution main line arc fault detection circuit

Abstract

The utility model aims to provide the arc fault detection circuit for the multi-branch distribution main line, which has the advantages of low cost and high reliability, and fault arc characteristics are extracted in real time through main/branch current vector difference, so that early and accurate early warning of arc faults of a distribution system is realized, and the operation safety of the power system is effectively improved. The utility model comprises a main line, a plurality of parallel branches and sampling resistors, wherein the main line is provided with a first current transformer, the branches are provided with a second current transformer, the secondary output end of the first current transformer and the secondary parallel output end of the second current transformer are connected to the two ends of the sampling resistors through opposite polarities, and the sampling resistors are connected with a singlechip through an operational amplifier. The utility model is applied to the technical field of electric safety monitoring.

Inventors

• QIU CHENGHAO
• Nie Changbao
• CHAI QIAN
• DING ZHAOLIN
• CHEN WEIQI
• GUO MOLIN
• SU BEI
• CHEN TONG

Assignees

• 珠海启能科技有限公司

Dates

Publication Date

20260508

Application Date

20250515

Claims (4)

1. 1. The multi-branch distribution main line arc fault detection circuit comprises a main line (1) and a plurality of branches (2) connected in parallel, and is characterized by further comprising a sampling resistor (R1), wherein the main line (1) is provided with a first current transformer (CT 0), the branches (2) are provided with a second current transformer (CT 1), the secondary output end of the first current transformer (CT 0) and the secondary parallel output end of the second current transformer (CT 1) are connected to the two ends of the sampling resistor (R1) through opposite polarities, and the sampling resistor (R1) is connected with a singlechip (4) through an operational amplifier (3).
2. 2. The multi-branch distribution main line arc fault detection circuit according to claim 1, wherein the current signal obtained by integrating the first current transformer (CT 0) and the second current transformer (CT 1) reversely passes through a third current transformer and is further output to the sampling resistor (R1) to obtain an arc discharge current signal Vd.
3. 3. The multi-branch distribution main line arc fault detection circuit according to claim 2, characterized in that the sampling resistor (R1) has a voltage at both ends vd=k (I total- Σi branch (2)), K being a scaling factor, and being precisely determined by circuit parameters, when an arc occurs, the main/branch (2) current is unbalanced, I total +Σibranch (2), vd presents a signal voltage.
4. 4. The multi-branch distribution main line arc fault detection circuit according to claim 1, wherein the sampling resistor (R1) is of a manganese-copper alloy structure, the resistance value is 50mΩ+ -1%, and the temperature coefficient is less than or equal to 50ppm/°C.

Description

Multi-branch distribution main line arc fault detection circuit Technical Field The utility model is applied to the technical field of electrical safety monitoring, and particularly relates to a multi-branch distribution main line arc fault detection circuit. Background In the existing arc detection technology, single-loop high-frequency signal analysis focuses on the single-loop condition only, and it is difficult to accurately position a main line and a branch fault point in a multi-branch distribution system. When facing the complex working condition of multiple branches, the system errors are continuously overlapped, so that the detection sensitivity is rapidly reduced, and potential fault hidden danger cannot be timely perceived. However, as disclosed in chinese patent publication No. CN207586360U, a fault arc detection device is disclosed, and the temperature threshold judgment can reflect the fault to a certain extent, but is limited by the hysteresis of the temperature change, and cannot respond quickly at the initial stage of the arc. In addition, the high-frequency sampling circuit is high in cost, is easily interfered by surrounding electromagnetic environment, and seriously affects the accuracy and reliability of a detection result. Therefore, the arc fault detection circuit of the multi-branch distribution main line is low in cost and high in reliability, fault arc characteristics are extracted in real time through main/branch current vector differences, early and accurate early warning of arc faults of a distribution system is achieved, and operation safety of the power system is effectively improved. Disclosure of utility model The utility model aims to solve the technical problems of overcoming the defects of the prior art, and provides a multi-branch distribution main line arc fault detection circuit which is low in cost and high in reliability, and fault arc characteristics are extracted in real time through main/branch current vector difference, so that early and accurate early warning of arc faults of a distribution system is realized, and the operation safety of the power system is effectively improved. The technical scheme includes that the intelligent power supply comprises a main line, a plurality of parallel branches and sampling resistors, wherein the main line is provided with a first current transformer, the branches are provided with second current transformers, the secondary output ends of the first current transformers and the secondary parallel output ends of the second current transformers are connected to two ends of the sampling resistors through opposite polarities, and the sampling resistors are connected with a singlechip through operational amplifiers. According to the scheme, the first current transformer and the second current transformer are reversely connected into the sampling resistor, and high-frequency arc characteristics in unbalanced current are directly extracted. Compared with the traditional scheme, the detection sensitivity is improved by more than 3 times, the cost is reduced by 60%, the method is particularly suitable for early arc fault early warning of a multi-branch distribution system, and through practical test verification, the method is excellent in performance under a complex distribution environment, safe driving and protecting navigation of the power system are realized, fault arc characteristics are extracted in real time through main/branch current vector differences, early accurate early warning of the arc fault of the power distribution system is realized, and the operation safety of the power system is effectively improved. In one preferred scheme, the current signal collected by the first current transformer and the second current transformer reversely passes through the third current transformer and is further output to the sampling resistor to obtain the arc discharge current signal Vd. In a preferred embodiment, the voltage vd=k (I total- Σi branch) at the two ends of the sampling resistor, K is a scaling factor, and is precisely determined by circuit parameters, when an arc occurs, the main/branch current is unbalanced, I total is not equal to Σi branch, and Vd represents the signal voltage. In a preferred scheme, the sampling resistor is of a manganese-copper alloy structure, the resistance is 50mΩ+/-1%, and the temperature coefficient is less than or equal to 50ppm/°c. Drawings Fig. 1 is a schematic circuit diagram of the present utility model. Detailed Description As shown in fig. 1, in this embodiment, the present utility model includes a main line 1, a plurality of parallel branches 2, and a sampling resistor R1, where the main line 1 is provided with a first current transformer CT0, the branches 2 are provided with a second current transformer CT1, a secondary output end of the first current transformer CT0 and a secondary parallel output end of the second current transformer CT1 are connected to two ends of the sampling resist