CN109100611B - Method for measuring 35KV distribution network capacitance current by phase control type arc suppression coil - Google Patents
Method for measuring 35KV distribution network capacitance current by phase control type arc suppression coil Download PDFInfo
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- CN109100611B CN109100611B CN201810853410.9A CN201810853410A CN109100611B CN 109100611 B CN109100611 B CN 109100611B CN 201810853410 A CN201810853410 A CN 201810853410A CN 109100611 B CN109100611 B CN 109100611B
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- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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Abstract
The invention discloses a system for measuring 35KV distribution network capacitance current by a phase-controlled arc suppression coil, which comprises the phase-controlled arc suppression coil, an in-situ control cabinet, a microcomputer controller, a single-phase voltage transformer, a single-phase current transformer and a single-pole isolating switch, wherein the phase-controlled arc suppression coil comprises a primary winding and a secondary winding, and the in-situ control cabinet comprises a power frequency signal injection device; the system and the method can still realize accurate measurement of the capacitance and current of the power grid when the asymmetric voltage of the distribution network system is very small, and have the advantages of convenient realization, low cost, high controllability and high reliability, and can not influence the work of the power grid.
Description
Technical Field
The invention relates to the technical field of power systems and automation thereof, in particular to a system and a method for measuring 35KV distribution network capacitance current by a phase-controlled arc suppression coil.
Background
In a 35kV distribution network system, according to regulation, when the system capacitance current exceeds 10A, an arc suppression coil is arranged to suppress arc overvoltage generated when a single-phase is grounded, so that the phenomenon that a single-phase fault is developed into an interphase short circuit to cause switch tripping is avoided. At present, domestic arc suppression coils mainly comprise three types of turn regulation type, phase control type and capacitance regulation type, wherein the phase control type arc suppression coil is more and more widely used because of the advantages of continuous stepless regulation of compensation current, quick response, simple structure, convenience in installation and maintenance and the like.
The neutral point of a 35kV distribution network system is usually led out, and the arc suppression coil can be directly connected to the neutral point of the system without adopting a grounding transformer. For the phase-control arc suppression coil used for the 35kV distribution network system, because the asymmetric voltage of the neutral point of the distribution network system is usually very small, if a conventional power grid capacitance current measurement method is adopted, the measurement error is very large sometimes, and sometimes even the measurement cannot be carried out, so that the normal work of the phase-control arc suppression coil is influenced.
Disclosure of Invention
In order to solve the technical problems, the invention provides a system and a method for measuring 35kV distribution network capacitance current by a phase control type arc suppression coil, namely a power frequency voltage signal injection method.
The invention adopts a technical scheme that: the system for measuring 35KV distribution network capacitance current by the phase-controlled arc suppression coil comprises the phase-controlled arc suppression coil, wherein the phase-controlled arc suppression coil comprises a primary winding and a secondary winding, the secondary winding comprises a control winding and a filter winding, a neutral point of the 35KV distribution network system is respectively connected with the primary winding and a neutral point single-phase current transformer in series, the primary winding is grounded through the neutral point, and the single-phase voltage transformer is connected with the phase-controlled arc suppression coil in parallel;
the secondary winding is electrically connected with the local control cabinet, the local control cabinet comprises a first power bidirectional thyristor and a filter bank, the first power bidirectional thyristor is electrically connected with the control winding, the filter bank is electrically connected with the filter winding, a signal injection device is arranged in the local control cabinet and is connected with the filter bank in parallel, the signal injection device comprises a miniature single-phase step-down transformer, a second power bidirectional thyristor and a resistor, the primary winding of the miniature single-phase step-down transformer is electrically connected with a 220V alternating-current power frequency power supply, and the secondary winding of the miniature single-phase step-down transformer is respectively connected with the second power bidirectional thyristor and the resistor in series;
one end of the single-phase current transformer and one end of the single-phase voltage transformer are respectively in signal connection with a microcomputer controller, the local control cabinet is in signal connection with the microcomputer controller, the microcomputer controller respectively controls the conduction of the first power bidirectional thyristor and the second power bidirectional thyristor, and the microcomputer controller respectively collects and processes data of the single-phase current transformer and the single-phase voltage transformer;
under the condition that the second power bidirectional thyristor is not conducted, the single-phase voltage transformer measures out asymmetric voltage U of a system neutral pointbdAfter the microcomputer controller controls the conduction of the second power bidirectional thyristor, the power frequency voltage signal is injected into the 35KV distribution network system to measure the output voltage U of the single-phase voltage transformerAXOutput current I of single-phase current transformerZRated phase of the systemVoltage is UeThrough Ubd、UAX、IZ、UeObtaining the capacitance current I of the distribution network systemC。
As a preferred scheme, the calculation method is specifically as follows:
the equivalent circuit of the system corresponds to the vector relation as follows:
it can be derived that: u shape2 C= U2 AX+ U2 bd- 2 UAXUbdCOSθ
The calculation formula of the 35KV distribution network capacitance current is as follows:
XC= UC/ Iz
IC= Ue/ XC。
a method for measuring 35KV distribution network capacitance current by a phase control type arc suppression coil specifically comprises the following steps:
step 1: asymmetric voltage of neutral point of 35KV distribution network system is measured
bd；
Step 2: injecting the power frequency voltage signals into a 35KV distribution network system, and respectively measuring the output voltage at the moment
AXAt this time, the output current Iz；
And step 3: rated phase voltage of system is UeThrough Ubd、UAX、IZ、UeIs calculated to obtainCapacitance current I of distribution network systemC。
As a preferred scheme, the calculation method is specifically as follows:
the equivalent circuit of the system corresponds to the vector relation as follows:
it can be derived that: u shape2 C= U2 AX+ U2 bd- 2 UAXUbdCOSθ
The calculation formula of the 35KV distribution network capacitance current is as follows:
XC= UC/ Iz
IC= Ue/ XC。
the invention has the beneficial effects that: the method can still realize the accurate measurement of the capacitance current of the power grid when the asymmetric voltage of the distribution network system is very small, and meanwhile, the method is convenient to realize, low in cost and high in reliability, and cannot influence the work of the power grid.
Drawings
Fig. 1 is a schematic wiring diagram of a system for measuring 35KV distribution network capacitance current by a phase control type arc suppression coil according to an embodiment of the invention.
Fig. 2 is a schematic diagram of the connection of the power frequency signal injection device according to the embodiment of the invention.
Fig. 3 is an equivalent circuit schematic diagram of the system of the embodiment of the invention when measuring the capacitance current of the 35KV distribution network.
Fig. 4 is a vector relationship diagram corresponding to fig. 3 according to an embodiment of the present invention.
Reference numerals:
the power supply comprises a 1-phase control type arc suppression coil, a 2-local control cabinet, a 3-microcomputer controller, a 4-single-phase voltage transformer, a 5-single-phase current transformer, a 6-signal injection device, a 7-single-pole isolating switch, an 8-miniature single-phase step-down transformer, a 9-second power bidirectional thyristor, a 10-resistor, an 11-a 1x1 control winding and a 12-a 2x2 filtering winding.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
referring to the attached drawings 1 and 2, the invention discloses a system for measuring 35KV distribution network capacitance current by a phase-controlled arc suppression coil, which comprises the phase-controlled arc suppression coil 1, wherein the phase-controlled arc suppression coil 1 comprises a primary winding and a secondary winding, the secondary winding comprises a control winding 11 and a filter winding 12, a neutral point of a 35KV distribution network system is respectively connected with the primary winding and a neutral point single-phase current transformer 5 in series, the primary winding is grounded through the neutral point, and a single-phase voltage transformer 4 is connected with the phase-controlled arc suppression coil 1 in parallel;
the secondary winding is electrically connected with the local control cabinet 2, a first power bidirectional thyristor and a filter bank are arranged in the local control cabinet 2, the first power bidirectional thyristor is electrically connected with the control winding, the filter bank is electrically connected with the filter winding 12, a signal injection device 6 is arranged in the local control cabinet 2, the signal injection device 6 is connected with the filter bank in parallel, the signal injection device 6 comprises a miniature single-phase step-down transformer 8, a second power bidirectional thyristor 7 and a resistor 10, a primary winding of the miniature single-phase step-down transformer 8 is electrically connected with a 220V alternating-current power frequency power supply, and a secondary winding of the miniature single-phase step-down transformer 8 is respectively connected with the second power bidirectional thyristor 9 and the;
one end of a single-phase current transformer 5 and one end of a single-phase voltage transformer 4 are respectively in signal connection with a microcomputer controller 3, a local control cabinet 2 is in signal connection with the microcomputer controller 3, the microcomputer controller 3 respectively controls a first power bidirectional thyristor and a second power bidirectional thyristor 9 to be conducted, and the microcomputer controller 3 respectively collects data of the single-phase current transformer 5 and the single-phase voltage transformer 4;
under the condition that the second power bidirectional thyristor 9 is not conducted, the single-phase voltage transformer 4 measures the asymmetric voltage U of the neutral point of the systembdAfter the microcomputer controller 3 controls the second power bidirectional thyristor 9 to be conducted, a power frequency voltage signal is injected into a 35KV distribution network system to measure the output voltage U of the single-phase voltage transformer 4AXThe single-phase current transformer 5 outputs a current IZThe rated phase voltage of the system is UeThrough Ubd、UAX、IZ、UeObtaining the capacitance current I of the distribution network systemC。
Example 2:
based on the embodiment 1, the microcomputer controller 3 includes a signal conditioner connected to the single-phase voltage transformer 4 and the single-phase current transformer 5 and conditioning the acquired signals, an a/D converter connected to the signal conditioner and performing analog-to-digital conversion on the signals, a processor connected to the a/D converter and processing the converted numbers, a photo isolator connected to the processor and performing photo-electric isolation processing on the sent first triac and second triac action commands, and a triac east-making command processed by the photo-electric isolation processing makes the first triac and the second triac act; the processor is also connected with a liquid crystal display and keyboard operation module.
Example 3:
with reference to fig. 3 and 4, based on embodiment 1, a method for measuring 35KV distribution network capacitance current by using a phase-controlled arc suppression coil is provided, which specifically includes the following steps:
step 1: asymmetric voltage of neutral point of 35KV distribution network system is measured
bd；
Step 2: injecting the power frequency voltage signals into a 35KV distribution network system, and respectively measuring the output voltage at the moment
AXAt this time, the output current Iz；
And step 3: rated phase voltage of system is UeThrough Ubd、UAX、IZ、UeCalculating to obtain the capacitance current I of the distribution network systemC。
The calculation method is specifically as follows:
the equivalent circuit of the system corresponds to the vector relation as follows:
from the cosine theorem, it can be derived: u shape2 C= U2 AX+ U2 bd- 2 UAXUbdCOSθ
The calculation formula of the 35KV distribution network capacitance current is as follows:
XC= UC/ Iz
IC= Ue/ XC。
FIG. 3 is an equivalent schematic diagram of the measurement of the capacitance current, wherein XLThe equivalent reactance of the primary side of the phase-controlled arc suppression coil is C', the equivalent capacitance of the primary side is converted by a filter circuit, and the equivalent capacitance of the system to the ground is C; u shapebdIs the system asymmetric voltage, and Iz is the primary loop current; fig. 4 is a vector relationship corresponding to fig. 3.
The working process of the invention is as follows: the primary winding of the phase-control arc suppression coil is used as a working winding to be connected to a neutral point of a power distribution network, the control winding 11 is electrically connected with the first bidirectional thyristor, the conduction angle of the first bidirectional thyristor is adjusted to be changed between 0-180 degrees, the equivalent impedance of the first bidirectional thyristor is changed between infinity and zero, and the output compensation current can be changed from zero to a rated valueThe values are continuously and steplessly adjusted. Meanwhile, a filter winding 12 is designed to eliminate harmonic generated when the first bidirectional thyristor is conducted, so that the output current is kept as power frequency current; under the condition that the second power bidirectional thyristor 9 is not conducted, the single-phase voltage transformer 4 measures the asymmetric voltage U of the neutral point of the systembdAfter the microcomputer controller 3 controls the conduction of the second power bidirectional thyristor 9, the output voltage U of the single-phase voltage transformer 4 is measuredAXOutput current I of single-phase current mutual 5 inductorZThe rated phase voltage of the system is UeThrough Ubd、UAX、IZ、UeObtaining the capacitance current I of the distribution network system according to the corresponding calculation formulaC。
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (1)
1. A method for measuring 35KV distribution network capacitance current by a phase control type arc suppression coil is characterized by comprising a system for measuring 35KV distribution network capacitance current by the phase control type arc suppression coil, wherein the system comprises the phase control type arc suppression coil (1), the phase control type arc suppression coil (1) comprises a primary winding and a secondary winding, the secondary winding comprises a control winding (11) and a filter winding (12), a neutral point of the 35KV distribution network system is respectively connected with the primary winding and a neutral point single-phase current transformer (5) in series, the primary winding is grounded through a neutral point, and a single-phase voltage transformer (4) is connected with the phase control type arc suppression coil (1) in parallel;
the secondary winding is electrically connected with the local control cabinet (2), the local control cabinet (2) comprises a first power bidirectional thyristor and a filter bank, the first power bidirectional thyristor is electrically connected with the control winding, the filter bank is electrically connected with the filter winding (12), a signal injection device (6) is arranged in the local control cabinet (2), the signal injection device (6) is connected with the filter bank in parallel, the signal injection device (6) comprises a miniature single-phase step-down transformer (8), a second power bidirectional thyristor (9) and a resistor (10), the primary winding of the miniature single-phase step-down transformer (8) is electrically connected with a 220V alternating-current power frequency power supply, and the secondary winding of the miniature single-phase step-down transformer (8) is respectively connected with the second power bidirectional thyristor (9) and the resistor (10) in;
one end of a single-phase current transformer (5) and one end of a single-phase voltage transformer (4) are respectively in signal connection with a microcomputer controller (3), a local control cabinet (2) is in signal connection with the microcomputer controller (3), the microcomputer controller (3) respectively controls a first power bidirectional thyristor and a second power bidirectional thyristor (9) to be conducted, and the microcomputer controller (3) respectively collects and processes data of the single-phase current transformer (5) and the single-phase voltage transformer (4);
under the condition that the second power bidirectional thyristor (9) is not conducted, the single-phase voltage transformer (4) measures the asymmetric voltage U of the neutral point of the systembdAfter the microcomputer controller (3) controls the second power bidirectional thyristor (9) to be conducted, a power frequency voltage signal is injected into a 35KV distribution network system to measure the output voltage U of the single-phase voltage transformer (4)AXThe single-phase current transformer (5) outputs current IZThe rated phase voltage of the system is UeThrough Ubd、UAX、IZ、UeObtaining the capacitance current I of the distribution network systemC；
The method specifically comprises the following steps:
step 1: asymmetric voltage of neutral point of 35KV distribution network system is measured
Step 2: injecting the power frequency voltage signals into a 35KV distribution network system, and respectively measuring the output voltage at the moment
At this time, the output current Iz；
And step 3: rated phase voltage of system is UeThrough Ubd、UAX、IZ、UeCalculating to obtain the capacitance current I of the distribution network systemC；
The calculation method is specifically as follows:
the equivalent circuit of the system corresponds to the vector relation as follows:
it can be derived that: u shape2 C＝U2 AX+U2 bd-2UAXUbdCOSθ
The calculation formula of the 35KV distribution network capacitance current is as follows:
XC＝UC/Iz
IC＝Ue/XC。
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| CN110470899B (en) * | 2019-07-03 | 2021-08-27 | 中山职业技术学院 | Method for measuring capacitance current of power distribution network based on membership function |
| CN110535116A (en) * | 2019-09-10 | 2019-12-03 | 北京华电瑞通电力工程技术有限公司 | A kind of arc extinction cabinet and small current neutral grounding system |
| CN113219377B (en) * | 2021-04-30 | 2024-02-02 | 西安热工研究院有限公司 | Generator primary loop inspection method based on injection type stator grounding protection device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201204451Y (en) * | 2008-07-01 | 2009-03-04 | 乐山一拉得电网自动化有限公司 | Intelligent arc-suppression coil plant |
| CN206931998U (en) * | 2017-04-28 | 2018-01-26 | 乐山一拉得电网自动化有限公司 | A kind of blowout coil set apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201204451Y (en) * | 2008-07-01 | 2009-03-04 | 乐山一拉得电网自动化有限公司 | Intelligent arc-suppression coil plant |
| CN206931998U (en) * | 2017-04-28 | 2018-01-26 | 乐山一拉得电网自动化有限公司 | A kind of blowout coil set apparatus |
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