CN109164387A - Generator unit stator winding Injection Current measurement method based on big small-range CT - Google Patents

Generator unit stator winding Injection Current measurement method based on big small-range CT Download PDF

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Publication number
CN109164387A
CN109164387A CN201811158166.0A CN201811158166A CN109164387A CN 109164387 A CN109164387 A CN 109164387A CN 201811158166 A CN201811158166 A CN 201811158166A CN 109164387 A CN109164387 A CN 109164387A
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CN
China
Prior art keywords
current
range
measured value
injection current
small
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201811158166.0A
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Chinese (zh)
Inventor
郑玉平
李蔚
吴崇昊
李志坚
潘书燕
郑作伟
郝后堂
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nari Technology Co Ltd
NARI Nanjing Control System Co Ltd
Original Assignee
Nari Technology Co Ltd
NARI Nanjing Control System Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nari Technology Co Ltd, NARI Nanjing Control System Co Ltd filed Critical Nari Technology Co Ltd
Priority to CN201811158166.0A priority Critical patent/CN109164387A/en
Publication of CN109164387A publication Critical patent/CN109164387A/en
Pending legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34Testing dynamo-electric machines
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only

Abstract

The generator unit stator winding Injection Current measurement method based on big small-range CT that the invention discloses a kind of, specially, it will be in the different current transformer series connection access stator winding infusion circuit of two ranges, carry out the measurement of Injection Current, and it is compared by wide range current transformer measured value with electric current threshold value, it realizes switching at runtime, determines the measured value of Injection Current.The present invention improves Injection Current measurement dynamic range using the current measuring method of the high dynamic range of big small-range CT.

Description

Generator unit stator winding Injection Current measurement method based on big small-range CT
Technical field
The generator unit stator winding Injection Current measurement method based on big small-range CT that the present invention relates to a kind of, belongs to electric power System automation control technology field.
Background technique
Current large-scale generator unit neutral point both at home and abroad mainly uses the earthing mode of grounded transformer, stator winding Ground protection mostly uses additional power source injected type stator ground protection, and injection component injects from unit neutral point.The protection by Ground resistance protection and power frequency zero sequence ground connection overcurrent protection collectively constitute, and two kinds of protection protection scope overlappings are realized without dead zone 100% range stator ground fault protection.
The accurate measurement of Injection Current determines ground resistance measurement accuracy and ground resistance protective value.Unit is in static When operating condition, the electric current in infusion circuit is minimum, needs accurately to measure;Unit is in grid-connected operating condition, and generator terminal metallic earthing occurs Failure, the electric current in infusion circuit are maximum, it is also desirable to accurate measurement.Curent change range is very big in infusion circuit, is more than general Device Current Transmit range of dynamic measurement, accurate measurement difficulty are big.
Summary of the invention
The technical problem to be solved by the present invention is to overcome the deficiencies of existing technologies, provide a kind of based on big small-range CT's Generator unit stator winding Injection Current measurement method, by the different current transformer of two ranges of connecting in infusion circuit, Determine the measured value of Injection Current.
To achieve the above object, The technical solution adopted by the invention is as follows:
Generator unit stator winding infusion circuit current measuring method based on big small-range CT, comprising the following steps:
1) two different current transformers of measuring range are connected in infusion circuit;
2) the secondary output electric current I of measuring device measurement wide range current transformerlargeWith small-range current transformer Secondary output electric current Ismall
3) switching judging for carrying out the Injection Current measured value of different range current transformers, determines the measurement of Injection Current Value.
In aforementioned step 3), the switching deciding method of Injection Current measured value are as follows:
By the secondary output electric current I of wide range current transformerlargeWith the electric current threshold value I of settingsw_thresholdCompared Compared with if Ilarge≥Isw_threshold, then Injection Current measured value IrelUsing the measured value I of wide range current transformerlarge; If Ilarge< Isw_threshold, then Injection Current measured value IrelUsing the measured value I of small-range current transformersmall, switching Logic are as follows:
What the present invention reached has the beneficial effect that
The present invention improves Injection Current measurement dynamic using the current measuring method of the high dynamic range of big small-range CT Range.
Detailed description of the invention
The different current transformer of two measuring ranges of Fig. 1 method to realize the present invention accesses infusion circuit schematic diagram.
Specific embodiment
The invention will be further described below.Following embodiment is only used for clearly illustrating technical side of the invention Case, and not intended to limit the protection scope of the present invention.
The method of the present invention is connected in infusion circuit using the different current transformer (abbreviation CT) of two measuring ranges, Measuring device measures the secondary output electric current of wide range CT and the secondary output electric current of small-range CT respectively.The amount of current transformer Journey depends on the range of Injection Current, and precision of the big current transformer of range when measuring high current is high, the small electric current of range Precision of the mutual inductor when measuring low current is high, and external wiring diagram is as shown in Figure 1, the primary side of grounding transformer is generator Group, secondary side are load resistance Rn, the additional supply-injected U of stator low frequency of secondary sideinject_source, two current transformer series connection In the secondary side of grounding transformer.
Of the invention method particularly includes:
1) the secondary output electric current I of measuring device measurement wide range CTlargeWith the secondary output electric current of small-range CT Ismall
2) switching judging of the Injection Current measured value of different range current transformers, deterministic process are carried out are as follows:
By the secondary output electric current I of wide range CTlargeWith the electric current threshold value I of settingsw_thresholdIt is compared, if Ilarge≥Isw_threshold, then Injection Current measured value IrelUsing the measured value I of wide range CTlarge;If Ilarge< Isw_threshold, then Injection Current measured value IrelUsing the measured value I of small-range CTsmall, switch logic are as follows:
The setting of electric current threshold value is similarly dependent on the range of Injection Current, rule of thumb sets.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art For member, without departing from the technical principles of the invention, several improvement and deformations can also be made, these improvement and deformations Also it should be regarded as protection scope of the present invention.

Claims (2)

1. the generator unit stator winding Injection Current measurement method based on big small-range CT, which comprises the following steps:
1) two different current transformers of measuring range are connected in infusion circuit;
2) the secondary output electric current I of measuring device measurement wide range current transformerlargeIt is secondary with small-range current transformer Export electric current Ismall
3) switching judging for carrying out the Injection Current measured value of different range current transformers, determines the measured value of Injection Current.
2. the generator unit stator winding Injection Current measurement method according to claim 1 based on big small-range CT, special Sign is, in the step 3), the switching deciding method of Injection Current measured value are as follows:
By the secondary output electric current I of wide range current transformerlargeWith the electric current threshold value I of settingsw_thresholdIt is compared, If Ilarge≥Isw_threshold, then Injection Current measured value IrelUsing the measured value I of wide range current transformerlarge;If Ilarge< Isw_threshold, then Injection Current measured value IrelUsing the measured value I of small-range current transformersmall, switch logic Are as follows:
CN201811158166.0A 2018-09-30 2018-09-30 Generator unit stator winding Injection Current measurement method based on big small-range CT Pending CN109164387A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811158166.0A CN109164387A (en) 2018-09-30 2018-09-30 Generator unit stator winding Injection Current measurement method based on big small-range CT

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811158166.0A CN109164387A (en) 2018-09-30 2018-09-30 Generator unit stator winding Injection Current measurement method based on big small-range CT

Publications (1)

Publication Number Publication Date
CN109164387A true CN109164387A (en) 2019-01-08

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110112712A (en) * 2019-04-30 2019-08-09 广东电网有限责任公司 Power distribution network earth protective device and its sampling control method with the configuration of double mutual inductors
CN110501570A (en) * 2019-09-17 2019-11-26 上海贝岭股份有限公司 Device for measurement of electrical energy and its current measurement mechanism

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CN207488353U (en) * 2017-10-23 2018-06-12 许继电气股份有限公司 A kind of current conversion station earthing pole enters ground cable current monitoring system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110112712A (en) * 2019-04-30 2019-08-09 广东电网有限责任公司 Power distribution network earth protective device and its sampling control method with the configuration of double mutual inductors
CN110501570A (en) * 2019-09-17 2019-11-26 上海贝岭股份有限公司 Device for measurement of electrical energy and its current measurement mechanism
CN110501570B (en) * 2019-09-17 2021-08-27 上海贝岭股份有限公司 Electric energy measuring device and current measuring mechanism thereof

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Application publication date: 20190108