Small current fault line selection system based on piezoelectric ceramic voltage acquisition

Abstract

The present invention provides a small current fault line selection system based on piezoelectric ceramic voltage acquisition, comprising: a power cable, a zero-sequence current transformer, an overhead conductor, a piezoelectric ceramic voltage transformer, a waveform recorder, a small current fault line selection device and a processor; the line relative ground voltage is acquired by the piezoelectric ceramic voltage transformer, and the line zero-sequence current transformer acquires the line zero-sequence current when the line fails; when the jump of the line zero-sequence current or the line relative ground voltage exceeds the trigger value of the waveform recorder, the voltage and current waveforms can be recorded by the waveform recorder, and the recorded current and voltage waveform data can be transmitted to the processor, so that the processor can judge the fault type according to the above current and voltage waveforms, and then transmit the fault line signal to the small current fault line selection device, which can provide sufficient data support including the line zero-sequence current and the line relative ground voltage for accurate analysis of the fault line, and can be used as an auxiliary means for line selection of the small current line selection device.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a small current fault line selection system based on piezoelectric ceramic voltage acquisition. Background Art

[0002] As the end of the power grid and the power source for electricity users, the reliable and stable operation of 10kV and 35kV distribution lines is crucial to the power supply reliability of the power grid and the production of electricity users. When a single-phase grounding fault occurs in the distribution line, it is necessary to accurately determine the faulty line, urgently cut off the faulty line and take corresponding safety measures to avoid further aggravation of the fault.

[0003] In the prior art, a small current fault line selection device is usually used to determine the faulty line. A small current fault line selection device is a monitoring device installed in a substation and used to determine line faults when a single-phase grounding occurs in a distribution line. At present, the small current fault line selection device on the market usually uses the characteristics that the zero-sequence current of the faulty line flows from the line to the busbar, while the zero-sequence current of the non-faulty line flows from the busbar to the line, and the two directions are opposite, and the zero-sequence current of the faulty line lags behind the zero-sequence voltage by 90° to determine the faulty line.

[0004] However, in practice, since the zero-sequence current generated when the distribution line is single-phase grounded is the system capacitance current, the value is very small, which makes the detection method based on zero-sequence current and zero-sequence voltage less sensitive. In addition, it is difficult to accurately determine the fault line by relying solely on zero-sequence current and zero-sequence voltage. Only by combining the multi-faceted data of the distribution line and complementing the advantages of multiple criteria can the misjudgment caused by a single criterion be reduced. Therefore, the existing small current fault line selection device cannot provide sufficient data support for the accurate analysis of the fault line. Summary of the invention

[0005] The purpose of the present invention is to provide a small current fault line selection system based on piezoelectric ceramic voltage acquisition to solve the problem that the existing small current fault line selection device cannot provide sufficient data support for accurate analysis of the fault line.

[0006] The present invention provides a small current fault line selection system based on piezoelectric ceramic voltage acquisition, comprising:

[0007] Power cables, zero-sequence current transformers, overhead conductors, piezoelectric ceramic voltage transformers, waveform recorders, small current fault line selection devices and processors;

[0008] The power cable includes an A-phase busbar, a B-phase busbar, and a C-phase busbar; the overhead conductor includes a first overhead conductor connected to the A-phase busbar, a second overhead conductor connected to the B-phase busbar, and a third overhead conductor connected to the C-phase busbar; the piezoelectric ceramic voltage transformer includes a first piezoelectric ceramic voltage transformer, a second piezoelectric ceramic voltage transformer, and a third piezoelectric ceramic voltage transformer;

[0009] The A-phase busbar, the B-phase busbar, and the C-phase busbar constitute a three-core cable, the zero-sequence current transformer is sleeved on the periphery of the three-core cable, and the zero-sequence current transformer is connected to the waveform recorder;

[0010] The top of the first piezoelectric ceramic voltage transformer is connected to the first overhead conductor, and a voltage tap is led out from the bottom; the top of the second piezoelectric ceramic voltage transformer is connected to the second overhead conductor, and a voltage tap is led out from the bottom; the top of the third piezoelectric ceramic voltage transformer is connected to the third overhead conductor, and a voltage tap is led out from the bottom; the voltage taps of the first piezoelectric ceramic voltage transformer, the second piezoelectric ceramic voltage transformer, and the third piezoelectric ceramic voltage transformer are respectively connected to the waveform recorder;

[0011] The waveform recorder is connected to the processor, and the processor is connected to the small current fault line selection device.

[0012] Optionally, the power cable further includes a grounding wire, wherein the grounding wire is located on one side of the three-core cable, and the grounding wire passes through the zero-sequence current transformer.

[0013] Optionally, the zero-sequence current transformer is connected to the waveform recorder via an insulated conductor.

[0014] Optionally, the voltage level of the insulated wire is 0.6 to 1 KV.

[0015] Optionally, the voltage taps of the second piezoelectric ceramic voltage transformer and the third piezoelectric ceramic voltage transformer are respectively connected to the waveform recorder via a coaxial cable.

[0016] It can be seen from the above technical scheme that the present invention provides a small current fault line selection system based on piezoelectric ceramic voltage acquisition, including: power cables, zero-sequence current transformers, overhead conductors, piezoelectric ceramic voltage transformers, waveform recorders, small current fault line selection devices and processors; the line relative ground voltage is collected by the piezoelectric ceramic voltage transformer, and the line zero-sequence current transformer collects the line zero-sequence current when the line fails. When the jump of the line zero-sequence current or the line relative ground voltage exceeds the trigger value of the waveform recorder, the voltage and current waveforms can be recorded by the waveform recorder, and the recorded current and voltage waveform data can be transmitted to the processor, so that the processor can judge the fault type according to the above current and voltage waveforms, and then transmit the fault line signal to the small current fault line selection device. The small current fault line selection system based on piezoelectric ceramic voltage acquisition provided by the present invention can provide sufficient data support including line zero-sequence current and line relative ground voltage for accurate analysis of the fault line. As an auxiliary means for the small current line selection device to select the line, by combining various aspects of the distribution line data, the advantages of multiple criteria are complemented, thereby reducing the misjudgment caused by a single criterion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic diagram of a small current fault line selection system based on piezoelectric ceramic voltage acquisition provided by the present invention.

[0019] Figure 2 A schematic diagram of the installation of a zero-sequence current transformer of a small current fault line selection system based on piezoelectric ceramic voltage acquisition provided by the present invention.

[0020] Illustration: 1-power cable, 2-zero-sequence current transformer, 3-overhead conductor, 4-piezoelectric ceramic voltage transformer, 5-insulated conductor, 6-waveform recorder, 7-coaxial cable, 8-small current fault line selection device, 9-processor, 10-three-core cable, 11-A phase bus, 12-B phase bus, 13-C phase bus, 14-ground wire, 31-first overhead conductor, 32-second overhead conductor, 33-third overhead conductor, 41-first piezoelectric ceramic voltage transformer, 42-second piezoelectric ceramic voltage transformer, 43-third piezoelectric ceramic voltage transformer. DETAILED DESCRIPTION

[0021] See also Figure 1 to Figure 2The embodiment of the present invention provides a small current fault line selection system based on piezoelectric ceramic voltage acquisition, including: a power cable 1, a zero-sequence current transformer 2, an overhead conductor 3, a piezoelectric ceramic voltage transformer 4, a waveform recorder 6, a small current fault line selection device 8 and a processor 9.

[0022] The power cable 1 includes an A-phase busbar 11, a B-phase busbar 12, and a C-phase busbar 13. In this embodiment, the power cable 1 is a three-phase four-wire transmission line. The overhead conductor 3 includes a first overhead conductor 31 connected to the A-phase busbar 11, a second overhead conductor 32 connected to the B-phase busbar 12, and a third overhead conductor 33 connected to the C-phase busbar 13.

[0023] The piezoelectric ceramic voltage transformer 4 includes a first piezoelectric ceramic voltage transformer 41, a second piezoelectric ceramic voltage transformer 42 and a third piezoelectric ceramic voltage transformer 43. In addition, the first piezoelectric ceramic voltage transformer 41, the second piezoelectric ceramic voltage transformer 42 and the third piezoelectric ceramic voltage transformer 43 can also be replaced by other forms of voltage transformers. Compared with other forms of transformers, the piezoelectric ceramic voltage transformer used in this embodiment has lower cost and is easy to put into operation in the substation. During installation, it is equivalent to adding only one pillar insulator, which is easy to install.

[0024] The A-phase busbar 11, the B-phase busbar 12, and the C-phase busbar 13 constitute a three-core cable 10, the zero-sequence current transformer 2 is sleeved on the periphery of the three-core cable 10, and the zero-sequence current transformer 2 is connected to the waveform recorder 6. In this embodiment, when installing the zero-sequence current transformer 2, the zero-sequence current transformer 2 can be clamped at the lower part of the cable head of the three-core cable 10. In addition, the power cable 1 also includes a grounding wire 14, which is located on one side of the three-core cable 10, and the grounding wire 14 passes through the zero-sequence current transformer 2, wherein the zero-sequence current transformer 2 is connected to the waveform recorder 6 through an insulated conductor 5, and is used to transmit the zero-sequence current data collected by the zero-sequence current transformer 2 to the waveform recorder 6 for recording.

[0025] Since the magnitude of the zero-sequence current of the fault line is equal to the sum of the zero-sequence currents of all non-fault lines, and the direction of the zero-sequence current of the fault line is opposite to that of the zero-sequence current of the non-fault line, the zero-sequence current data collected by the zero-sequence current transformer 2 can be used to make a fault judgment according to the current direction to identify whether it is a fault of the current line. In this embodiment, the insulated conductor 5 is a low-voltage insulated conductor with a voltage level of 0.6 to 1KV.

[0026] Specifically, the top of the first piezoelectric ceramic voltage transformer 41 is connected to the first overhead conductor 31, and a voltage tap is led out from the bottom to collect the relative ground voltage of the first overhead conductor 31. The top of the second piezoelectric ceramic voltage transformer 42 is connected to the second overhead conductor 32, and a voltage tap is led out from the bottom to collect the relative ground voltage of the second overhead conductor 32. The top of the third piezoelectric ceramic voltage transformer 43 is connected to the third overhead conductor 33, and a voltage tap is led out from the bottom to collect the relative ground voltage of the third overhead conductor 33. In this embodiment, the first piezoelectric ceramic voltage transformer 41, the second piezoelectric ceramic voltage transformer 42, and the third piezoelectric ceramic voltage transformer 43 can respectively and continuously collect the relative ground voltages of the first overhead conductor 31, the second overhead conductor 32, and the third overhead conductor 33.

[0027] The voltage taps of the first piezoelectric ceramic voltage transformer 41, the second piezoelectric ceramic voltage transformer 42, and the third piezoelectric ceramic voltage transformer 43 are respectively connected to the waveform recorder 6, and are used to transmit the relative ground voltage data of the first overhead wire 31, the second overhead wire 32, and the third overhead wire 33 to the waveform recorder 6 for recording. In this embodiment, the voltage taps of the second piezoelectric ceramic voltage transformer 42 and the third piezoelectric ceramic voltage transformer 43 are respectively connected to the waveform recorder 6 through a coaxial cable 7.

[0028] Furthermore, the waveform recorder 6 is connected to the processor 9, and the processor 9 is connected to the small current fault line selection device 8. The waveform recorder 6 can transmit the recorded relative ground voltage data of the first overhead wire 31, the second overhead wire 32 and the third overhead wire 33, and the zero-sequence current data collected by the zero-sequence current transformer 2 to the processor 9, so that the processor 9 can judge the fault type according to the above current and voltage waveforms, and then transmit the fault line signal to the small current fault line selection device 8.

[0029] It should be emphasized that the present application only involves providing sufficient data support including line zero-sequence current and line relative ground voltage to processor 9 for accurate analysis of the fault line through a new hardware architecture. The technical problem solved by the present application is limited to solving the problem that the existing hardware architecture cannot provide sufficient data support for accurate analysis of the fault line through the hardware architecture connection relationship of the system, and does not involve improvements to the program of processor 9 of the present application, that is, the software program of processor 9 is not required to solve the technical problem of the present application.

[0030] In this embodiment, the waveform recorder 6 is in a standby state when the line is operating normally. If a line fault occurs, the relative ground voltage data of the first overhead wire 31, the second overhead wire 32 and the third overhead wire 33, and the jump of the zero-sequence current data collected by the zero-sequence current transformer 2 exceed the trigger value of the waveform recorder 6, then the waveform recorder 6 starts and synchronously records the relative ground voltage waveforms of the first overhead wire 31, the second overhead wire 32 and the third overhead wire 33, and the zero-sequence current waveform collected by the zero-sequence current transformer 2. In addition, the waveform recorder 6 can also be manually triggered to record the relative ground voltage waveforms of the first overhead wire 31, the second overhead wire 32 and the third overhead wire 33, and the zero-sequence current waveform collected by the zero-sequence current transformer 2. The above functions of the waveform recorder 6 can be implemented according to the existing technology.

[0031] When a small current fault line selection system based on piezoelectric ceramic voltage acquisition provided by an embodiment of the present invention is installed on site, the zero-sequence current transformer 2 can be first clamped on the lower part of the cable head of the three-core cable 10, so that the A-phase bus 11, the B-phase bus 12, and the C-phase bus 13 pass through the zero-sequence current transformer 2, and the ground wire 14 also passes through the zero-sequence current transformer 2. Then, the zero-sequence current transformer 2 is connected to the waveform recorder 6. Afterwards, the first piezoelectric ceramic voltage transformer 41, the second piezoelectric ceramic voltage transformer 42 and the third piezoelectric ceramic voltage transformer 43 are respectively installed on the first overhead wire 31, the second overhead wire 32 and the third overhead wire 33 to collect the line relative to ground voltage, and the first piezoelectric ceramic voltage transformer 41, the second piezoelectric ceramic voltage transformer 42 and the third piezoelectric ceramic voltage transformer 43 are connected to the waveform recorder 6 through the coaxial cable 7, and finally the waveform recorder 6 is connected to the processor 9 through a data line.

[0032] It can be seen from the above technical solutions that a small current fault line selection system based on piezoelectric ceramic voltage acquisition provided in an embodiment of the present invention includes: a power cable 1, a zero-sequence current transformer 2, an overhead conductor 3, a piezoelectric ceramic voltage transformer 4, a waveform recorder 6, a small current fault line selection device 8 and a processor 9. The power cable 1 includes an A-phase bus 11, a B-phase bus 12 and a C-phase bus 13; the overhead conductor 3 includes a first overhead conductor 31 connected to the A-phase bus 11, a second overhead conductor 32 connected to the B-phase bus 12, and a third overhead conductor 33 connected to the C-phase bus 13; the piezoelectric ceramic voltage transformer 4 includes a first piezoelectric ceramic voltage transformer 41, a second piezoelectric ceramic voltage transformer 42 and a third piezoelectric ceramic voltage transformer 43. The A-phase busbar 11, the B-phase busbar 12, and the C-phase busbar 13 constitute a three-core cable 10, and the zero-sequence current transformer 2 is set on the periphery of the three-core cable 10, and the zero-sequence current transformer 2 is connected to the waveform recorder 6; the top of the first piezoelectric ceramic voltage transformer 41 is connected to the first overhead wire 31, and the voltage tap is led out from the bottom; the top of the second piezoelectric ceramic voltage transformer 42 is connected to the second overhead wire 32, and the voltage tap is led out from the bottom; the top of the third piezoelectric ceramic voltage transformer 43 is connected to the third overhead wire 33, and the voltage tap is led out from the bottom; the voltage taps of the first piezoelectric ceramic voltage transformer 41, the second piezoelectric ceramic voltage transformer 42 and the third piezoelectric ceramic voltage transformer 43 are respectively connected to the waveform recorder 6; a small current fault line selection system based on piezoelectric ceramic voltage acquisition provided in an embodiment of the present invention, through piezoelectric ceramic The voltage transformer 4 collects the line relative to the ground voltage, and the zero-sequence current transformer 2 collects the line zero-sequence current when the line fails. When the jump of the line zero-sequence current or the line relative to the ground voltage exceeds the trigger value of the waveform recorder 6, the voltage and current waveforms can be recorded by the waveform recorder 6, and the recorded current and voltage waveform data can be transmitted to the processor 9, so that the processor 9 can judge the fault type according to the above current and voltage waveforms, and then transmit the fault line signal to the small current fault line selection device 8. The small current fault line selection system based on piezoelectric ceramic voltage collection provided by the present invention can provide sufficient data support including line zero-sequence current and line relative to the ground voltage for accurate analysis of the fault line. As an auxiliary means for the small current line selection device to select the line, by combining various data of the distribution line, the advantages of multiple criteria are complemented, thereby reducing the misjudgment caused by a single criterion.

[0033] The above embodiments of the present invention do not limit the protection scope of the present invention.

Claims

1. A small current fault line selection system based on piezoelectric ceramic voltage acquisition, characterized in that: include: Power cable (1), zero-sequence current transformer (2), overhead conductor (3), piezoelectric ceramic voltage transformer (4), waveform recorder (6), small current fault line selection device (8) and processor (9); The power cable (1) comprises an A-phase busbar (11), a B-phase busbar (12) and a C-phase busbar (13); the overhead conductor (3) comprises a first overhead conductor (31) connected to the A-phase busbar (11), a second overhead conductor (32) connected to the B-phase busbar (12), and a third overhead conductor (33) connected to the C-phase busbar (13); the piezoelectric ceramic voltage transformer (4) comprises a first piezoelectric ceramic voltage transformer (41), a second piezoelectric ceramic voltage transformer (42) and a third piezoelectric ceramic voltage transformer (43); The A-phase busbar (11), the B-phase busbar (12), and the C-phase busbar (13) form a three-core cable (10); the zero-sequence current transformer (2) is sleeved on the periphery of the three-core cable (10); and the zero-sequence current transformer (2) is connected to the waveform recorder (6); The top of the first piezoelectric ceramic voltage transformer (41) is connected to the first overhead conductor (31), and a voltage tap is led out from the bottom; the top of the second piezoelectric ceramic voltage transformer (42) is connected to the second overhead conductor (32), and a voltage tap is led out from the bottom; the top of the third piezoelectric ceramic voltage transformer (43) is connected to the third overhead conductor (33), and a voltage tap is led out from the bottom; the voltage taps of the first piezoelectric ceramic voltage transformer (41), the second piezoelectric ceramic voltage transformer (42), and the third piezoelectric ceramic voltage transformer (43) are respectively connected to the waveform recorder (6); The waveform recorder (6) is connected to the processor (9), and the processor (9) is connected to the small current fault line selection device (8); The voltage taps of the second piezoelectric ceramic voltage transformer (42) and the third piezoelectric ceramic voltage transformer (43) are respectively connected to the waveform recorder (6) via a coaxial cable (7).

2. The small current fault line selection system based on piezoelectric ceramic voltage acquisition according to claim 1 is characterized in that: The power cable (1) further comprises a grounding wire (14), wherein the grounding wire (14) is located on one side of the three-core cable (10), and the grounding wire (14) passes through the zero-sequence current transformer (2).

3. The small current fault line selection system based on piezoelectric ceramic voltage acquisition according to claim 1 is characterized in that: The zero-sequence current transformer (2) is connected to the waveform recorder (6) via an insulated conductor (5).

4. The small current fault line selection system based on piezoelectric ceramic voltage acquisition according to claim 3 is characterized in that: The voltage level of the insulated wire (5) is 0.6-1KV.

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