CN112782575B - Current measuring device for circuit breaker, maintenance and correction method of current measuring device and intelligent circuit breaker - Google Patents

Current measuring device for circuit breaker, maintenance and correction method of current measuring device and intelligent circuit breaker Download PDF

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CN112782575B
CN112782575B CN202011571300.7A CN202011571300A CN112782575B CN 112782575 B CN112782575 B CN 112782575B CN 202011571300 A CN202011571300 A CN 202011571300A CN 112782575 B CN112782575 B CN 112782575B
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current
intelligent controller
current transformer
measuring device
circuit breaker
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CN112782575A (en
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殷建强
周龙明
叶文杰
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Changshu Switchgear Manufacturing Co Ltd
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Changshu Switchgear Manufacturing Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • 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
    • G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
    • G01R31/3277—Testing of circuit interrupters, switches or circuit-breakers of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measurement Of Current Or Voltage (AREA)

Abstract

The invention discloses a current measuring device for a circuit breaker, which comprises an intelligent controller and a current transformer connected with the intelligent controller, wherein a memory of the intelligent controller stores a current correction coefficient of the current measuring device; and the memory of the intelligent controller is also stored with the measurement error of the current transformer. The invention also discloses a maintenance and correction method of the current measuring device for the circuit breaker and an intelligent circuit breaker. By adopting the technical scheme of the invention, when the used intelligent circuit breaker has an intelligent controller fault or a current transformer fault, a service worker only needs to correspondingly replace the intelligent controller or the current transformer and can carry out correction on the current measurement accuracy on site by a simple maintenance correction method, thereby effectively reducing the service cost.

Description

Current measuring device for circuit breaker, maintenance and correction method of current measuring device and intelligent circuit breaker
Technical Field
The invention relates to a circuit breaker, in particular to a current measuring device for the circuit breaker.
Background
In a low-voltage distribution system, a controller of an intelligent circuit breaker takes a microcontroller as a core, and the protection, measurement and monitoring functions of the circuit breaker are realized through signal sampling, data processing and fault diagnosis. With the development of smart power grids and digital technologies, requirements for realizing energy efficiency management are provided for smart circuit breakers, and requirements for measuring accuracy of main electrical parameters such as current, power and electric energy are higher and higher. Generally, a current measurement method of an intelligent circuit breaker is to first sample a current by using a current transformer (generally, a Rogowski coil is used), and then calculate a current measurement value by performing integration reduction, signal conditioning, AD conversion, and the like by using an intelligent controller, so that the current measurement accuracy mainly depends on the measurement accuracy of the current transformer and the intelligent controller. When an intelligent circuit breaker leaves a factory and corrects the measurement accuracy of the whole machine current, an intelligent controller and a current transformer are regarded as a complete measurement system, the error of the measurement system is usually corrected in the correction process through a communication test port and other modes, and a correction coefficient is stored in a Flash Memory (Flash Memory) or an E2PROM, and the like. However, after the intelligent circuit breaker is used for a long time, the intelligent controller or the current transformer may have a fault and must be replaced, otherwise, unnecessary loss may be caused to a client. Three fault situations may occur:
1. only the intelligent controller fails. The original current transformer in the circuit breaker has a certain measurement error, and the current transformer cannot be corrected, so that a new intelligent controller for replacement cannot be matched with the original current transformer, the accuracy of the current measurement of the whole machine is reduced, and the standard requirement of a product cannot be met.
2. Only the current transformer fails. The new current transformer for replacement has a certain measurement error, cannot be corrected, cannot be matched with the original intelligent controller of the circuit breaker, reduces the accuracy of the current measurement of the whole machine, and cannot meet the standard requirement of products.
3. The intelligent controller and the current transformer both have faults. At the moment, the intelligent controller and the current transformer can only be replaced simultaneously, the new intelligent controller is matched with the new current transformer, the current measurement accuracy of the whole machine is corrected, and the product standard requirement is met.
According to the statistical analysis of the actual faults of the intelligent circuit breaker, the 1 st fault and the 2 nd fault are the majority, and the 3 rd fault is few. At present, when the intelligent circuit breaker in use has a fault of an intelligent controller or a current transformer, if a service person only replaces the fault intelligent controller or the fault current transformer correspondingly, the current accuracy is not convenient to correct on site due to limited on-site inspection conditions. Therefore, in order to enable the whole breaker to still meet the high-precision measurement requirement specified by the product standard, service personnel can only generally replace the original intelligent controller of the breaker with the current transformer and replace the original intelligent controller with a new matched intelligent controller and the new matched intelligent controller with the current transformer, so that the service cost is greatly improved.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art and provide a current measuring device for a circuit breaker and a maintenance and correction method thereof.
The invention specifically adopts the following technical scheme to solve the technical problems:
a current measuring device for a circuit breaker comprises an intelligent controller and a current transformer connected with the intelligent controller, wherein a current correction coefficient of the current measuring device is stored in a memory of the intelligent controller; and the memory of the intelligent controller is also stored with the measurement error of the current transformer.
Preferably, the current transformer is a rogowski coil.
The method for maintaining and correcting the current measuring device for the circuit breaker according to any one of the above technical solutions,
after the old smart controller is replaced with a new smart controller, the measurement error L 'of the current transformer is first read from the memory of the old smart controller'XReading an original current correction coefficient K from a memory of the new intelligent controller; the new current correction factor K' is then calculated according to the following equation:
Figure BDA0002862813240000021
finally, update K in memory of new smart controller with K ', L'XAnd updating the measurement error of the original current transformer in the memory of the intelligent controller.
After the old current transformer is replaced by a new current transformer, the original current correction coefficient K and the measurement error L of the old current transformer are read from the memory of the intelligent controllerX(ii) a Then according to the measurement error L of the new current transformer "XThe new current correction factor K "is calculated using the following equation:
Figure BDA0002862813240000022
finally, K' is used for updating K in the memory of the intelligent controller, and L is used "XUpdating L in memory of intelligent controllerX。
Preferably, the measurement error L of the new current transformer "XThe current transformer is obtained from a record or parameter label which is backed up before the current transformer leaves a factory.
An intelligent circuit breaker comprises a current measuring device, wherein the current measuring device is the current measuring device for the circuit breaker in any one technical scheme.
Compared with the prior art, the invention has the following beneficial effects:
according to the technical scheme, the problem of overhigh maintenance cost in the prior art is thoroughly solved by pre-storing the calibrated measurement error of the current transformer in the intelligent controller, when the used intelligent circuit breaker has an intelligent controller fault or a current transformer fault, a service worker only needs to correspondingly replace the intelligent controller or the current transformer, the current measurement accuracy can be corrected on site by a simple maintenance correction method, and the service cost is effectively reduced.
Detailed Description
In order to solve the problem of waste caused by the fact that the current measuring device is integrally replaced in order to ensure that the current measuring accuracy of the intelligent circuit breaker meets the standard requirement after maintenance in the prior art, the invention aims to solve the problem that the current measuring device is additionally stored with the measuring error of the pre-calibrated current transformer in addition to the current correction coefficient of the current measuring device consisting of the intelligent controller and the current transformer in the intelligent controller. Therefore, when the used intelligent circuit breaker has an intelligent controller fault or a current transformer fault, service personnel only need to correspondingly replace the intelligent controller or the current transformer and can carry out correction on the current measurement accuracy on site by a simple maintenance correction method, thereby effectively reducing the service cost.
Specifically, the current measuring device for the circuit breaker comprises an intelligent controller and a current transformer connected with the intelligent controller, wherein a memory of the intelligent controller stores a current correction coefficient of the current measuring device; and the memory of the intelligent controller is also stored with the measurement error of the current transformer.
Taking a three-wire four-wire breaker as an example, the method for maintaining and correcting the current measuring device for the breaker,
after replacing the old intelligent controller with a new intelligent controller, the measurements of the current transformers are first read from the memory of the old intelligent controllerError L'iXAnd reading the original current correction coefficient K from the memory of the new intelligent controlleri(ii) a A new current correction factor K 'is then calculated as follows'i：
Figure BDA0002862813240000041
Finally K 'is used'iUpdating K in memory of a new intelligent controlleriL 'from'iXUpdating the measurement error of the original current transformer in the memory of the intelligent controller;
after the old current transformer is replaced by a new current transformer, the original current correction coefficient K is read from the memory of the intelligent controlleriAnd measurement error L of old current transformeriX(ii) a Then according to the measurement error L ″' of the new current transformeriXThe new current correction factor K' is calculated using the formulai：
Figure BDA0002862813240000042
Finally using KiUpdating K in memory of intelligent controlleriBy LiXUpdating L in memory of intelligent controlleriX；
Wherein wheniWhen each is A, B, C, N, LiXRepresents the measurement error of the old current transformer of A, B, C, N phases; l'iXA measurement error representing the A, B, C, N-phase current transformer stored in the old intelligent controller; l ″)iXIndicating the measurement error L ″' of the A, B, C, N-phase new current transformeriX；KiCurrent correction factors representing the original A, B, C, N phase of the new intelligent controller; k'iCurrent correction coefficients representing the A, B, C, N phases after the new intelligent controller updates; k ″)iIndicating the current correction factor for the A, B, C, N phase after the old intelligent controller update.
The measurement error L' of the new current transformeriXThe current transformer is obtained from a record or parameter label which is backed up before the current transformer leaves a factory.
For the public understanding, the technical scheme of the invention is explained in detail by a specific embodiment:
flash Memory or E of the intelligent controller2In PROM and other nonvolatile memory, the correction coefficient K of each phase current of current measuring device composed of intelligent controller and current transformer is storedA、KB、KC、KNBesides, the measurement error L of each phase current transformer which is calibrated in advance is additionally storedAX、LBX、LCX、LNX。
The measurement error of the current transformer adopts relative error, which is defined as:
relative error is (measured value-true value)/true value x 100%, where true value may be the agreed true value.
The relationship between the current correction coefficient and the measurement error of the current transformer is as follows:
Ki＝Ki-ETU/(1+LiX)
wherein Ki-ETUAre the original correction coefficients of the intelligent controller, which are the measurement errors for correcting the intelligent controller, Ki-ETU＝1/(1+δi)，δiIs the measured relative error of the intelligent controller.
When the intelligent controller fails or the equipment is old and replaced, the current measurement accuracy of the intelligent circuit breaker after maintenance can be corrected on site by adopting the following method:
1) reading each phase current correction coefficient K in the new intelligent controller memory through the communication test portA、KB、KC、KN。
2) Measuring errors L 'according to the current transformers of the various phases stored in the memory of the intelligent controller to be replaced which is backed up'AX、L'BX、L'CX、L'NXCalculating to obtain a new phase current correction coefficient K'A、K'B、K'C、K'N：
Figure BDA0002862813240000051
Figure BDA0002862813240000052
Figure BDA0002862813240000053
Figure BDA0002862813240000054
3) Prepared from K'A、K'B、K'C、K'NSequentially writing the current values into the new intelligent controller memory through the communication test port, and correspondingly replacing the original current correction coefficients K of each phase in the new intelligent controller memoryA、KB、KC、KN。
4) L'AX、L'BX、L'CX、L'NXSequentially writing the L-shaped data into the new intelligent controller memory through the communication test port to correspondingly replace the L-shaped data stored in the new intelligent controller memoryAX、LBX、LCX、LNX。
Wherein each phase current transformer measures an error L'AX、L'BX、L'CX、L'NXCan be read from the replaced smart controller memory.
When the current transformer fails or the equipment is old and replaced, the current measurement accuracy of the intelligent circuit breaker after maintenance can be corrected on site by adopting the following method:
1) reading each phase current correction coefficient K in the intelligent controller memory through the communication test portA、KB、KC、KNAnd the measurement error L of the replaced phase current transformer (e.g., Rogowski coil)AX、LBX、LCX、LNX。
2) According to the new measuring error L of the current transformer of each phase "AX、L”BX、L”CX、L”NXCalculating to obtain newCorrection coefficient K of each phase current "A、K”B、K”C、K”N：
Figure BDA0002862813240000061
Figure BDA0002862813240000062
Figure BDA0002862813240000063
Figure BDA0002862813240000064
3) Will K "A、K”B、K”C、K”NSequentially writing the correction coefficients into the intelligent controller memory through the communication test port to correspondingly replace the original correction coefficients K of the currents of each phase in the intelligent controller memoryA、KB、KC、KN。
4) Mixing L'AX、L”BX、L”CX、L”NXSequentially writing in the intelligent controller memory through the communication test port to correspondingly replace the LAX、LBX、LCX、LNX。
Wherein, the new measuring error L of each phase current transformer "AX、L”BX、L”CX、L”NXThe current transformer can be obtained from a record or parameter label which is backed up before the current transformer leaves a factory.

Claims (6)

1. A maintenance correction method of a current measuring device for a circuit breaker comprises an intelligent controller and a current transformer connected with the intelligent controller, wherein a memory of the intelligent controller stores a current correction coefficient of the current measuring device and a measurement error of the current transformer; it is characterized in that the preparation method is characterized in that,
after the old smart controller is replaced with a new smart controller, the measurement error L 'of the current transformer is first read from the memory of the old smart controller'XReading an original current correction coefficient K from a memory of the new intelligent controller; the new current correction factor K' is then calculated according to the following equation:
Figure FDA0003315935150000011
finally, update K in memory of new smart controller with K ', L'XAnd updating the measurement error of the original current transformer in the memory of the intelligent controller.
2. The method for maintaining and calibrating a current measuring device for a circuit breaker of claim 1, wherein said current transformer is a rogowski coil.
3. A maintenance correction method of a current measuring device for a circuit breaker comprises an intelligent controller and a current transformer connected with the intelligent controller, wherein a memory of the intelligent controller stores a current correction coefficient of the current measuring device and a measurement error of the current transformer; it is characterized in that the preparation method is characterized in that,
after the old current transformer is replaced by a new current transformer, the original current correction coefficient K and the measurement error L of the old current transformer are read from the memory of the intelligent controllerX(ii) a Then according to the measurement error L of the new current transformer "XThe new current correction factor K "is calculated using the following equation:
Figure FDA0003315935150000012
finally, K' is used for updating K in the memory of the intelligent controller, and L is used "XUpdating L in memory of intelligent controllerX。
4. The method for maintaining and calibrating a current measuring device for a circuit breaker of claim 3 wherein said current transformer is a rogowski coil.
5. Method for maintenance correction of current measuring devices for circuit breakers according to claim 3, characterised in that the measurement error L of the new current transformer is "XThe current transformer is obtained from a record or parameter label which is backed up before the current transformer leaves a factory.
6. An intelligent circuit breaker comprising a current measuring device, characterized in that said current measuring device uses the maintenance correction method according to claim 1 or 3.
CN202011571300.7A 2020-12-27 2020-12-27 Current measuring device for circuit breaker, maintenance and correction method of current measuring device and intelligent circuit breaker Active CN112782575B (en)

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