CN201508392U - Frequency-conversion grounding resistance measuring instrument - Google Patents

Frequency-conversion grounding resistance measuring instrument Download PDF

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Publication number
CN201508392U
CN201508392U CN2009201394433U CN200920139443U CN201508392U CN 201508392 U CN201508392 U CN 201508392U CN 2009201394433 U CN2009201394433 U CN 2009201394433U CN 200920139443 U CN200920139443 U CN 200920139443U CN 201508392 U CN201508392 U CN 201508392U
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CN
China
Prior art keywords
frequency
resistance measuring
measuring instrument
signal
variable
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CN2009201394433U
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Chinese (zh)
Inventor
蔡国清
陈世光
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福建省普华电子科技有限公司
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Priority to CN2009201394433U priority Critical patent/CN201508392U/en
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Publication of CN201508392U publication Critical patent/CN201508392U/en

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Abstract

The utility model relates to a frequency-conversion grounding resistance measuring instrument which is formed by a sampling circuit, a signal amplifying circuit, an A/D (analog-to-digital) converter, a singlechip, a variable frequency power source, a filtering frequency-selecting circuit and an upper computer, wherein the singlechip controls the variable frequency power source and a filtering frequency-selecting device, the variable frequency power source injects current into a ground net, and then the sampled circuit acquires current sampled signals and voltage sampling signals. After being detected by a signal line and being amplified, the sampled signals enter the A/D converter through filtering frequency-selection, and finally the direct display and the printing of measured results are realized through the singlechip. Since the grounding resistance measuring instrument utilizes the self-carried variable frequency power source, the interference caused to the ground net can be eliminated through filtering frequency-selection, and the measuring accuracy is high.

Description

The frequency conversion ground resistance measuring instrument

Technical field

The utility model belongs to electronic device, relates to the surveying instrument of ground network ground resistance, particularly a kind of frequency conversion ground resistance measuring instrument.

Background technology

Current, grounding resistance measurement mainly adopts the injection current method, promptly measures the electric current and the earth mat voltage that inject earth mat and calculates stake resistance.Operating transmission transformer station, the system's out-of-balance current that flows through geodetic network produces interference voltage on the net and can reach 7~8V on ground.Often start with during actual measurement, promptly adopt and strengthen injection current, reduce undesired signal and measuring-signal ratio and method such as removal undesired signal improves measurement in measurement result is calculated accuracy from improving the metering circuit signal to noise ratio (S/N ratio).But, can not fundamentally eliminate the influence of interference voltage for the method for system power supply as experiment power supply.The routine measurement method also is difficult to eliminate the mutual inductance between electric current and voltage and lead-in wire, and its measurement equipment set is bulky, has brought a lot of inconvenience to the site operation personnel.

Summary of the invention

The purpose of this utility model provides a kind of earth mat interference voltage of eliminating to be influenced with the lead-in wire mutual voltage, and the high frequency conversion ground resistance measuring instrument of the accuracy that not influenced by system power supply.

Order of the present utility model is achieved through the following technical solutions.

The frequency conversion ground resistance measuring instrument, form by sample circuit, signal amplification circuit, A/D converter, single-chip microcomputer, variable-frequency power sources, filtering frequency selection circuit, host computer, wherein: control the filtering frequency selector simultaneously by the Single-chip Controlling variable-frequency power sources, variable-frequency power sources is to the earth mat injection current, at this moment sample circuit is obtained current sample and voltage sampling signal, sampled signal is after signal wire detection and signal amplify, by the filtering frequency-selecting, enter A/D converter, pass through the direct demonstration and the printing of chip microcontroller measurement result at last.

Because the variable-frequency power sources that the utility model uses instrument to carry, earth mat disturbs through frequency-selective filtering and is eliminated, thereby measurement result is not subjected to the influence of system power supply; Can be because of whether earth mat is affected in the existence of operation or undesired signal, so the measuring accuracy height.Structure is rationally advanced in addition, can directly show and print the grounding resistance of earth mat.

Description of drawings

Fig. 1 the utility model structured flowchart

The tested earth mat sampling of Fig. 2 connects diagrammatic sketch

The spectrogram of earth mat undesired signal before Fig. 3 measures

Embodiment

Below in conjunction with accompanying drawing the utility model is further elaborated.

With reference to Fig. 1, this frequency conversion ground resistance measuring instrument mainly is made up of sample circuit, signal amplification circuit, A/D change-over circuit, single-chip microcomputer, variable-frequency power sources, filtering frequency selection circuit, host computer, and its sample circuit comprises current sample and voltage sample.Wherein the power of variable-frequency power sources is 400V * 5A; Signal amplifier adopts 2132; A/D converter has 24 high-precision AD7658; Single-chip microcomputer adopts ADUC7026; Host computer communication RS232.Control the filtering frequency selector simultaneously by the Single-chip Controlling variable-frequency power sources, variable-frequency power sources is to the earth mat injection current, at this moment sample circuit is obtained current sample and voltage sampling signal, sampled signal is after signal wire detection and signal amplify, by the filtering frequency-selecting, enter A/D converter, pass through the direct demonstration and the printing of chip microcontroller measurement result at last.

With reference to Fig. 2, G is an earth mat among the figure, and P is that voltage pole, C are that the electric current utmost point, S are variable-frequency power sources.To earth mat injection current I, the primary current of sample circuit current sensor change is at this moment obtained current sample i into secondary current, measures earth mat voltage simultaneously and obtains voltage sample U, stake resistance R when disregarding interference voltage by Single-chip Controlling variable-frequency power sources S G=U/I.Neutrality is clicked and entered the undesired signal of generations such as zero-sequence current on ground and useful signal and is superimposed and is gathered during sampling.Usually adopt phase place to differentiate and frequency is differentiated to remove and disturbed, but during earthmeter, the undesired signal frequency spectrum is very wide, phase place is difficult to determine, and the useful signal frequency is known, so frequency identification and extraction useful signal are the simplest.Therefore, this instrument adopts under the frequency of 40 hertz and 60 hertz and respectively surveys, filters measuring-signal by high precision filtering frequency selection circuit, the removal undesired signal.The value of Ji Suaning is converted under 50 hertz again divided by 2 at last, improves measuring accuracy.

With reference to Fig. 3, this figure presses the circuit of Fig. 2, transformer station at western suburb, Foochow 220KV carries out the earth mat experiment, spectrogram for earth mat undesired signal before measuring, near the general amplitude maximum 50 hertz and 150 hertz of earth mat undesired signal is going to zero below 35 hertz and between 60~110 hertz as seen from the figure.

With reference to above-listed each figure, the variable-frequency power sources that the frequency conversion mensuration uses instrument to carry, earth mat disturbs through frequency-selective filtering and is eliminated, thereby measurement result is not subjected to the influence of system power supply; Can whether not be affected because of earth mat in the existence of operation or undesired signal.Frequency variation method utilizes spectrum technology at first to measure earth mat undesired signal frequency spectrum, control testing power supply frequency makes it to be operated in undisturbed or disturbs on the less frequency range (facts have proved general just be sufficient for sb.'s need with 40Hz and 60Hz), adopt single-chip microcomputer to carry out data processing again, can be from measurement result the in-phase component of pick-up voltage electric current, eliminate the influence of lead-in wire mutual inductance and earth mat self-induction, directly show the ground network ground resistance value of measuring.

The key that the stake resistance frequency conversion is measured is digital filtering and signal processing technology, and digital filtering makes the system's existing more highland of selected frequency filtering precision with the algorithm that method of pole and Fourier transform method combine.Native system adopts 4 steps to finish measurement:

1, under the situation that all lines connect, do not add earlier any power source output, directly measure 40 hertz and 60 hertz of undesired signals that earth mat exists earlier, and measuring error that this undesired signal is brought is existed among the RAM, as fixed error.

2, by the measuring-signal of 40 hertz of Single-chip Controlling variable-frequency power sources outputs, control filtering circuit simultaneously and switch to 40 hertz of passages, by technology such as phase demodulation, frequency-selectings, calculate the earth mat resistance value under this frequency, and deposit among the RAM,

3, by the measuring-signal of 60 hertz of Single-chip Controlling variable-frequency power sources outputs, control filtering circuit simultaneously and switch to 60 hertz of passages,, calculate the earth mat resistance value under this frequency, and deposit among the RAM by technology such as phase demodulation, frequency-selectings.

4,1. get resistance R under 50 hertz being converted in the resistance value that records under 40 hertz 42. get resistance R under 50 hertz being converted in the resistance value that records under 60 hertz 63. the resistance value that records in undesired signal is converted to and gets resistance R under 50 hertz LCalculate the earth mat resistance R at last XComputing formula is as follows:

R X=(R 4-R 6)/2-R L

For improving the Electromagnetic Compatibility of electronic device, the utility model has been taked suitable interference protection measure, comprising: adopt metal foreign minister packing, select suitable earthing mode, the measure of selecting suitable power-supply filter for use and taking to handle various fortuitous events in software design.Design is used to upper computer software VC++Write upper computer software under the XP platform, the full Chinese in interface shows.The input of existing earth mat experiment place name, metering system, data preservation, measurement result demonstration, the inquiry of historical data, electric power laboratory report generate functions such as printing.

Claims (6)

1. frequency conversion ground resistance measuring instrument, it is characterized in that forming by sample circuit, signal amplification circuit, A/D converter, single-chip microcomputer, variable-frequency power sources, filtering frequency selection circuit, host computer, wherein: control the filtering frequency selector simultaneously by the Single-chip Controlling variable-frequency power sources, variable-frequency power sources is to the earth mat injection current, at this moment sample circuit is obtained current sample and voltage sampling signal, sampled signal is after signal wire detection and signal amplify, by the filtering frequency-selecting, enter A/D converter, pass through the direct demonstration and the printing of chip microcontroller measurement result at last.
2. frequency conversion ground resistance measuring instrument according to claim 1 is characterized in that described sample circuit comprises current sample and voltage sample.
3 frequency conversion ground resistance measuring instruments according to claim 1 is characterized in that its power of described variable-frequency power sources is 400V * 5A.
4. frequency conversion ground resistance measuring instrument according to claim 1 is characterized in that described measuring-signal frequency by monolithic processor controlled variable-frequency power sources output, is 40 hertz and 60 hertz.
5. frequency conversion ground resistance measuring instrument according to claim 1 is characterized in that described A/D converter has 24 high-precision AD7658.
6. frequency conversion ground resistance measuring instrument according to claim 1 is characterized in that described single-chip microcomputer adopts ADUC7026.
CN2009201394433U 2009-07-16 2009-07-16 Frequency-conversion grounding resistance measuring instrument CN201508392U (en)

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102087331A (en) * 2010-12-14 2011-06-08 四川电力试验研究院 Pilot frequency heavy-current multifunctional grounding parameter testing system based on variable frequency power supply
CN102095999A (en) * 2010-12-14 2011-06-15 重庆大学 Measuring device for diagnosing connecting state of grounding network
CN102540013A (en) * 2011-12-27 2012-07-04 广东电网公司韶关供电局 Transformer substation grounding network frequency response test device
CN102645577A (en) * 2012-05-03 2012-08-22 上海大帆电气设备有限公司 Digital frequency selection measuring system capable of resisting one hundred thousand times of interference
CN102707167A (en) * 2012-05-18 2012-10-03 华中科技大学 State monitoring system for grounding grid based on industrial personal computer
CN103163382A (en) * 2013-03-12 2013-06-19 中国铁路通信信号上海工程集团有限公司 Real-time online measurement system and method for resistance of ground wire
CN103207331A (en) * 2013-03-12 2013-07-17 中国铁路通信信号上海工程集团有限公司 System and method for monitoring damaged on-off quantity of surge protection device and ground resistance online in real time
WO2013117836A1 (en) 2012-02-08 2013-08-15 Renault S.A.S. Secure on-board system for charging the battery of a motor vehicle from a power supply network
WO2013171431A1 (en) 2012-05-16 2013-11-21 Renault S.A.S. System and method for secure charging of a motor vehicle battery
CN103941097A (en) * 2014-04-30 2014-07-23 国家电网公司 Large ground grid grounding resistance real-time monitor
CN104111372A (en) * 2014-05-08 2014-10-22 徐伟专 Analytical equipment of frequency conversion electricity based on digital transmission
CN104749444A (en) * 2013-12-31 2015-07-01 孙巍巍 Grounding resistance measuring device
CN104849563A (en) * 2015-05-05 2015-08-19 国家电网公司 Remote intelligent test device for loop resistance
CN104897968A (en) * 2015-05-14 2015-09-09 武汉市康达电气有限公司 Method for testing impedance of earth screen based on phase-inversion incremental method
CN105785135A (en) * 2016-04-11 2016-07-20 国网安徽省电力公司电力科学研究院 Frequency conversion ground impedometer
CN104379385B (en) * 2012-05-16 2016-11-30 雷诺股份公司 For the system and method to motor vehicle battery safe charging

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102095999A (en) * 2010-12-14 2011-06-15 重庆大学 Measuring device for diagnosing connecting state of grounding network
CN102087331A (en) * 2010-12-14 2011-06-08 四川电力试验研究院 Pilot frequency heavy-current multifunctional grounding parameter testing system based on variable frequency power supply
CN102540013A (en) * 2011-12-27 2012-07-04 广东电网公司韶关供电局 Transformer substation grounding network frequency response test device
WO2013117836A1 (en) 2012-02-08 2013-08-15 Renault S.A.S. Secure on-board system for charging the battery of a motor vehicle from a power supply network
CN104094126A (en) * 2012-02-08 2014-10-08 雷诺股份公司 Secure on-board system for charging the battery of motor vehicle from power supply network
CN104094126B (en) * 2012-02-08 2016-10-19 雷诺股份公司 For the onboard safety systems battery of motor vehicles charged by supply network
CN102645577A (en) * 2012-05-03 2012-08-22 上海大帆电气设备有限公司 Digital frequency selection measuring system capable of resisting one hundred thousand times of interference
CN104379385A (en) * 2012-05-16 2015-02-25 雷诺股份公司 System and method for secure charging of a motor vehicle battery
WO2013171431A1 (en) 2012-05-16 2013-11-21 Renault S.A.S. System and method for secure charging of a motor vehicle battery
FR2990763A1 (en) * 2012-05-16 2013-11-22 Renault Sa System and method for securely charging a motor vehicle battery
CN104379385B (en) * 2012-05-16 2016-11-30 雷诺股份公司 For the system and method to motor vehicle battery safe charging
US9637010B2 (en) 2012-05-16 2017-05-02 Renault S.A.S. System and method for secure charging of a motor vehicle battery
CN102707167A (en) * 2012-05-18 2012-10-03 华中科技大学 State monitoring system for grounding grid based on industrial personal computer
CN102707167B (en) * 2012-05-18 2015-04-15 华中科技大学 State monitoring system for grounding grid based on industrial personal computer
CN103163382B (en) * 2013-03-12 2016-04-06 中国铁路通信信号上海工程集团有限公司 Line resistance real-time online measuring system and method
CN103207331A (en) * 2013-03-12 2013-07-17 中国铁路通信信号上海工程集团有限公司 System and method for monitoring damaged on-off quantity of surge protection device and ground resistance online in real time
CN103207331B (en) * 2013-03-12 2015-07-29 中国铁路通信信号上海工程集团有限公司 The switching value that lightning protection device damages and stake resistance real time on-line monitoring system and method
CN103163382A (en) * 2013-03-12 2013-06-19 中国铁路通信信号上海工程集团有限公司 Real-time online measurement system and method for resistance of ground wire
CN104749444A (en) * 2013-12-31 2015-07-01 孙巍巍 Grounding resistance measuring device
CN103941097A (en) * 2014-04-30 2014-07-23 国家电网公司 Large ground grid grounding resistance real-time monitor
CN104111372A (en) * 2014-05-08 2014-10-22 徐伟专 Analytical equipment of frequency conversion electricity based on digital transmission
CN104849563A (en) * 2015-05-05 2015-08-19 国家电网公司 Remote intelligent test device for loop resistance
CN104897968A (en) * 2015-05-14 2015-09-09 武汉市康达电气有限公司 Method for testing impedance of earth screen based on phase-inversion incremental method
CN104897968B (en) * 2015-05-14 2017-08-08 武汉市康达电气有限公司 Mesh grounding impedance detecting method based on paraphase method of addition
CN105785135A (en) * 2016-04-11 2016-07-20 国网安徽省电力公司电力科学研究院 Frequency conversion ground impedometer

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Granted publication date: 20100616

Termination date: 20130716