CN104331115B - A kind of circuit and method eliminating PT secondary circuit voltage drop - Google Patents
A kind of circuit and method eliminating PT secondary circuit voltage drop Download PDFInfo
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- CN104331115B CN104331115B CN201410573106.0A CN201410573106A CN104331115B CN 104331115 B CN104331115 B CN 104331115B CN 201410573106 A CN201410573106 A CN 201410573106A CN 104331115 B CN104331115 B CN 104331115B
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Abstract
The invention discloses a kind of circuit eliminating PT secondary circuit voltage drop, comprise Secondary Circuit of Potential Transformer and electric energy meter, a voltage transformer (VT) endpiece resistive module in parallel in described secondary circuit, connection box of electric energy meter terminal place series connection access one voltage follower module in described secondary circuit; Described resistive module and voltage follower model calling one switching module, to be in voltage follower module by switching module controlling resistance module simultaneously and to be connected or off-state in Secondary Circuit of Potential Transformer.The invention also discloses a kind of method eliminating PT secondary circuit voltage drop.
Description
Technical field
The present invention relates to power industry, particularly a kind of circuit of elimination PT secondary circuit voltage drop of realizing based on voltage follower principle and method.
Background technology
The allowed band of all kinds of electric power meter PT secondary circuit voltage drop is defined in DL/T448-2000 " electric energy measuring management technical management code ".PT secondary circuit voltage drop is a hard nut to crack in electric power metering system, and existing achievement in research of dealing with problems is reported successively in recent years, mainly contains following several method:
(1) secondary circuit conductor impedance is reduced.Increase PT secondary circuit conductor cross-section, reduce conductor length, reduce components and parts contacts resistance in loop.
(2) PT secondary loop current is reduced, as adopted special PT secondary measurement loop.
(3) PT end by transform electrical signals be digital signal with Optical Fiber Transmission, convert digital signal to simulating signal for electric energy meter to eliminate secondary circuit voltage drop at electric power meter end.
(4) introduce compensation system and offset the ratio and angular difference that PT secondary circuit voltage drop causes.Compensation system has fixed value compensation device, current tracking formula compensator, voltage-tracing formula compensator etc.For voltage-tracing formula compensator, in real time measure PT secondary terminals voltage and electric energy meter meter terminal voltage, compensator produces a voltage superposition contrary with PT secondary circuit voltage drop equal and opposite in direction, direction in PT secondary circuit, makes pressure drop be equivalent to zero.
Method (1) (2) are common methods, but secondary circuit conductor impedance still exists, and passing in time, in loop, the oxidation of components and parts contact makes contact resistance become large, and pressure drop increases thereupon, is difficult to deal with problems at all.
The accuracy of method (3) front voltage measurement, the synchronism of digital-to-analog conversion, accuracy are the difficult points of the method, and a lot of occasion needs comparison, implement cost high.
Method (4) compensator needs cable laying to obtain comparison signal, and there is certain electromagnetic interference (EMI), bucking voltage also exists harmonic problem, there is the risk of over-compensation.
How no matter adopt, the accuracy of measuring must be ensured, meet measurement Law and existing " electric energy measuring management technical management code " specifies, embodiment fairness.
Summary of the invention
Goal of the invention: technical matters to be solved by this invention is for the deficiencies in the prior art, provides a kind of circuit and the method for eliminating PT secondary circuit voltage drop.
In order to solve the problems of the technologies described above, the invention discloses a kind of circuit eliminating PT secondary circuit voltage drop, in PT secondary circuit, one group of resistive module in parallel in voltage transformer (VT) endpiece place; In described secondary circuit, connect one group of voltage follower module in connection box of electric energy meter terminal place; Described resistive module and voltage follower model calling one switching module, be in connection or off-state simultaneously in the secondary circuit between voltage transformer (VT) and electric energy meter by switching module controlling resistance module and voltage follower module.
In circuit of the present invention, the impedance Z x of described resistive module meets following formula:
Zx＝Z+Z
2/Zin，
Wherein Z represents electric energy meter impedance, and Zin represents the impedance of voltage follower module input, is vector length angle value.
In circuit of the present invention, described voltage follower module adopts amplifier voltage follower.
In circuit of the present invention, the input end of described voltage follower module is connected monitoring module and monitors its duty with output terminal.
In circuit of the present invention, described cpu monitor module monitors voltage follower module output terminal load, voltage follower module temperature.
Described switching module, voltage follower module are powered by power module, the temperature of described monitoring module monitoring power module.
The invention also discloses a kind of circuit methods eliminating PT secondary circuit voltage drop, comprise PT secondary circuit and electric energy meter, parallel resistance module and series voltage follower module between voltage transformer (VT) and electric energy meter in described secondary circuit, described voltage follower module is by a cpu monitor module monitors duty, and whether described resistive module and voltage follower module control to be connected in the secondary circuit between voltage transformer (VT) and electric energy meter by a switching module; When monitoring module detects any phase voltage follower fault, any phase voltage follower input and output voltage is than out-of-limit, the overload of follower rear end, open circuit, follower input voltage is out-of-limit, during voltage follower module excess temperature, control switching module resistive module and whole voltage follower module to be excised from Secondary Circuit of Potential Transformer, momentary recovery voltage transformer (VT) is directly connected duty with electric energy meter simultaneously.
In the inventive method, the formula that arranges of the impedance Z x of described resistive module is:
Zx＝Z+Z
2/Zin，
Wherein Z represents electric energy meter impedance, and Zin represents the impedance of voltage follower module input, is vector length angle value.
Described switching module, voltage follower module are powered by power module, the temperature of described monitoring module monitoring power module, when power module exceedes safe temperature, control switching module resistive module and whole voltage follower module to be excised from PT Secondary Circuit of Potential Transformer, momentary recovery voltage transformer (VT) is directly connected duty with electric energy meter simultaneously.
In the present invention, resistive module, switching module, voltage follower module, monitoring module, thermal module, power module, communication module, display module can be integrated into a pressure drop accessing original circuit fast and eliminate complete equipment.
Compare with existing pressure drop technology for eliminating, the inventive method has following advantage:
1, the inventive method is eliminated accurately PT secondary circuit voltage drop, is equal to electric energy meter and directly obtains PT outlet voltage, can not produce lifting PT bis-exit potential problems.
2, the inventive method does not have an impact to PT precision, does not affect metering composition error.
3, the present invention has automatic switching function, and fault timer entirety exits loop, momentary recovery former PT secondary circuit duty, safe and reliable.
4, main functional modules of the present invention easily purchases production, and product technology is ripe, and installation is convenient.
5, the present invention can to multiple stage complete equipment Real-time Monitor Management.
6, be convenient to promote, social benefit is good, high financial profit.
Accompanying drawing explanation
To do the present invention below in conjunction with the drawings and specific embodiments and further illustrate, above-mentioned and/or otherwise advantage of the present invention will become apparent.
Fig. 1 is circuit diagram of the present invention.
Fig. 2 is apparatus of the present invention figure.
Embodiment
As depicted in figs. 1 and 2, the invention discloses a kind of circuit eliminating PT secondary circuit voltage drop, in PT secondary circuit, a resistive module in parallel in voltage transformer (VT) endpiece place; In described secondary circuit, connect one group of voltage follower module in connection box of electric energy meter terminal place; Described resistive module and voltage follower model calling one switching module, be in connection or off-state simultaneously in the secondary circuit between voltage transformer (VT) and electric energy meter by switching module controlling resistance module and voltage follower module.
In circuit of the present invention, the impedance Z x of described resistive module meets following formula:
Zx＝Z+Z
2/Zin，
Wherein Z represents electric energy meter impedance, and Zin represents the impedance of voltage follower module input, is vector length angle value.
In circuit of the present invention, described voltage follower module adopts amplifier voltage follower.
In circuit of the present invention, the input end of described voltage follower module is connected monitoring module and monitors its duty with output terminal.
In circuit of the present invention, described cpu monitor module monitors voltage follower module output terminal load, voltage follower module temperature.Described switching module, voltage follower module are powered by power module, the temperature of described monitoring module monitoring power module.
In the present invention, resistive module, switching module, voltage follower module, monitoring module, thermal module, power module, communication module, display module can be integrated into a pressure drop accessing original circuit fast and eliminate complete equipment.
The invention also discloses a kind of method eliminating PT secondary circuit voltage drop, in PT secondary circuit, a resistive module in parallel in voltage transformer (VT) endpiece place; In described secondary circuit, connect a voltage follower module in connection box of electric energy meter terminal place; Described resistive module and voltage follower model calling one switching module, be in connection or off-state simultaneously in the secondary circuit between voltage transformer (VT) and electric energy meter by switching module controlling resistance module and voltage follower module.When monitoring module detects any phase voltage follower fault, any phase voltage follower input and output voltage is than out-of-limit, the overload of follower rear end or open circuit, follower input voltage is out-of-limit, when follower module, device body excess temperature, control switching module resistive module and whole voltage follower module to be excised from PT secondary circuit, momentary recovery voltage transformer (VT) is directly connected duty with electric energy meter simultaneously.
In the inventive method, the formula that arranges of the impedance Z x of described resistive module is:
Zx＝Z+Z
2/Zin，
Wherein Z represents electric energy meter impedance, and Zin represents the impedance of voltage follower module input, is vector length angle value.
The principle of the invention is: voltage follower block coupled in series access electric power meter end in PT secondary circuit, knows that voltage follower module eliminates the pressure drop that in PT secondary circuit, impedance loop and PT internal impedance are produced by the amplifier voltage follower principle of work and power.Voltage follower front end loop current I ≈ 0, load is minimum, and loop is equivalent to open circuit.According to existing GB (JJG 10212007), the precision of PT is guaranteed in the scope that PT secondary circuit load meets 2.5VA ∽ rated load.That is, only use voltage follower to eliminate pressure drop, but PT measuring accuracy can not be ensured.PT secondary circuit is equivalent to open circuit, and simultaneously lifting PT outlet voltage, brings new error to electric energy metrical.In order to realize eliminating the object that PT secondary circuit voltage drop not only can ensure PT measuring accuracy but also not produce the new error of electric energy metrical simultaneously, solve problem in PT endpiece parallel connection access with the precision resistance module of electric energy meter impedance matching.The switching while that resistive module and voltage follower module being in PT secondary circuit.This method is equal to electric energy meter and directly obtains PT outlet voltage, accurately eliminates PT secondary circuit voltage drop.Resistive module, voltage follower module, monitoring module are that main modular device forms pressure drop elimination complete equipment, and monitoring module controls the action of switching module according to Detection Information, is embodied as the automatic switching of covering device.When complete equipment are normal or temporary derangement disappears, voltage follower module and resistive module are devoted oneself to work simultaneously, and PT secondary circuit is in pressure drop and eliminates duty, and former duty exits; Complete equipment fault or external electrical parameter out-of-limit time voltage follower module and resistive module deactivate simultaneously, momentary recovery former PT secondary circuit duty.
Embodiment
One, complete equipment of the present invention (comprise resistive module, switching module, voltage follower module, monitoring module, thermal module, power module, communication module, display module, can access original circuit fast and carry out pressure drop elimination.)：
1, realize phase three-wire three, three-phase and four-line PT secondary circuit voltage drop is automatically accurately eliminated.
2, device uses engineering plastics (or cast aluminium) shell hanging frame type to install, and working power is that 220V exchanges.
3, electrical principles circuit, DSP technology, GPRS (Ethernet) mechanics of communication is adopted, each function modoularization process.
4, monitoring module monitoring follow circuit module input and output voltage, PT secondary circuit voltage, complete equipment working power input and output voltage, device load, unit temp, device remote signalling state, store every Monitoring Data, storage be not less than 60 working day measurement data, can 3 months be kept after power-off.
5, monitoring module controls the action of switching module according to Detection Information, is embodied as the automatic switching of covering device.When complete equipment are normal or temporary derangement disappears, voltage follower module and resistive module are devoted oneself to work simultaneously, and PT secondary circuit is in pressure drop and eliminates duty, and former duty exits; During complete equipment fault, voltage follower module and resistive module are deactivated simultaneously, momentary recovery former PT secondary circuit duty.
6, the resistance Zx=Z+Z of resistive module is configured
2/ Zin, be electric power meter end impedance (resistance), Zin is voltage follower sending-end impedance, is vector length angle value.
7, resistance and PT rated load 2.5VA ~ 100% (new national standard JJG 10212007) or the rated load 25% ~ 100% (to the former PT still run of new national standard JJG 10212007) that configure resistive module are checked, when the resistive module resistance value of configuration is not within the scope of PT rated load, calculate configuration corresponding configuration resistance value by PT load lower limit 2.5VA or rated load 25%.
8, in concrete engineering application, if electric power meter end load meets PT secondary load (2.5VA or 25% ∽ 100% rated load) area requirement, directly calculated by electric energy meter Z, device Zin and determine Zx value; If electric power meter end load does not meet PT secondary load area requirement, meet PT bis-rated load lower limits requirement (2.5VA (new national standard JJG 10212007) or 25% rated load) by electric power meter end load and calculate Z, then determine Zx value by the Zin calculating of device.
The invention provides a kind of circuit and the method for eliminating PT secondary circuit voltage drop; the method and access of this technical scheme of specific implementation is a lot; the above is only the preferred embodiment of the present invention; should be understood that; for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.The all available prior art of each ingredient not clear and definite in the present embodiment is realized.
Claims (9)
1. eliminate the circuit of PT secondary circuit voltage drop for one kind, comprise Secondary Circuit of Potential Transformer and electric energy meter, it is characterized in that, voltage transformer (VT) endpiece one group of resistive module in parallel in described secondary circuit, in described secondary circuit, connect one group of voltage follower module in connection box of electric energy meter terminal place; Described resistive module and voltage follower model calling one switching module, to be in voltage follower module by switching module controlling resistance module simultaneously and to be connected or off-state in Secondary Circuit of Potential Transformer;
The resistance Zx of described one group of resistive module meets following formula:
Zx＝Z+Z
2/Zin，
Wherein Z represents electric energy meter impedance, and Zin represents the impedance of voltage follower module input, is vector length angle value.
2. a kind of circuit eliminating PT secondary circuit voltage drop according to claim 1, is characterized in that, described voltage follower module adopts amplifier voltage follower.
3. a kind of circuit eliminating PT secondary circuit voltage drop according to claim 1, is characterized in that, the input end of described voltage follower module is connected its duty of cpu monitor module monitors with output terminal.
4. a kind of circuit eliminating PT secondary circuit voltage drop according to claim 3, is characterized in that, described cpu monitor model calling voltage follower output terminal, exports back-end load for monitoring voltage follower.
5. a kind of circuit eliminating PT secondary circuit voltage drop according to claim 3, is characterized in that, described cpu monitor model calling thermal module, for the temperature of monitoring voltage follower module.
6. a kind of circuit eliminating PT secondary circuit voltage drop according to claim 4, is characterized in that, described switching module, voltage follower module are powered by power module, the temperature of described monitoring module monitoring power module.
7. eliminate the circuit methods of PT secondary circuit voltage drop for one kind, comprise PT Secondary Circuit of Potential Transformer and electric energy meter, it is characterized in that, parallel resistance module and series voltage follower module between voltage transformer (VT) and electric energy meter in described secondary circuit, described voltage follower module is by a cpu monitor module monitors duty, and whether described resistive module and voltage follower module control to be connected in the secondary circuit between voltage transformer (VT) and electric energy meter by a switching module simultaneously; When cpu monitor module detects any phase voltage follower fault, any phase voltage follower input and output voltage ratio exceedes setting value or the overload of voltage follower output terminal or open circuit or follower input voltage and exceedes setting safety value, or when voltage follower module exceedes safe temperature, control switching module resistive module and whole voltage follower module to be excised from PT Secondary Circuit of Potential Transformer, momentary recovery voltage transformer (VT) is directly connected duty with electric energy meter simultaneously.
8. a kind of circuit methods eliminating PT secondary circuit voltage drop according to claim 7, is characterized in that, the formula that arranges of the impedance Z x of described resistive module is:
Zx＝Z+Z
2/Zin，
Wherein Z represents electric energy meter impedance, and Zin represents the impedance of voltage follower module input, is vector length angle value.
9. a kind of circuit methods eliminating PT secondary circuit voltage drop according to claim 7, it is characterized in that, described switching module, voltage follower module are powered by power module, the temperature of described monitoring module monitoring power module, when power module exceedes safe temperature, control switching module resistive module and whole voltage follower module to be excised from PT Secondary Circuit of Potential Transformer, momentary recovery voltage transformer (VT) is directly connected duty with electric energy meter simultaneously.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410573106.0A CN104331115B (en) | 2014-10-23 | 2014-10-23 | A kind of circuit and method eliminating PT secondary circuit voltage drop |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410573106.0A CN104331115B (en) | 2014-10-23 | 2014-10-23 | A kind of circuit and method eliminating PT secondary circuit voltage drop |
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| CN104331115B true CN104331115B (en) | 2015-10-07 |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105158539B (en) * | 2015-07-20 | 2017-11-24 | 钱坤 | Method based on pressure drop cancellation element measurement PT secondary circuit voltage drops |
| CN110333475B (en) * | 2019-07-04 | 2022-12-23 | 中国电力科学研究院有限公司 | Method and system for determining voltage drop error of secondary circuit of voltage transformer under any secondary load |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS581388B2 (en) * | 1978-07-06 | 1983-01-11 | 株式会社東芝 | electricity meter |
| CN2170569Y (en) * | 1993-10-21 | 1994-06-29 | 苏州供电局 | Automatic compensator for secondary voltage drop of voltage transformer |
| CN2272155Y (en) * | 1996-02-08 | 1998-01-07 | 三门峡市电业局 | Secondary side line pressure-drop compensator of voltage transformer |
| CN2264372Y (en) * | 1996-03-01 | 1997-10-08 | 胡大林 | Secondary loop full voltage automatic compensator of voltage mutual-inductor |
| CN2265583Y (en) * | 1996-09-13 | 1997-10-22 | 刘山 | Self-adaptation compensator for potential transformer secondary circuit potential drop |
| CN100351634C (en) * | 2004-05-21 | 2007-11-28 | 郑州大学 | Compensation method for voltage transformer secondary circuit pressure drop and compensation arrangement |
| CN101086917A (en) * | 2006-06-09 | 2007-12-12 | 郑州大学 | Compensation method of voltage mutual inductor and secondary loop voltage reduction error and compensation device |
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