CN203658471U - Power frequency interference suppressing device for testing ground resistance - Google Patents
Power frequency interference suppressing device for testing ground resistance Download PDFInfo
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- CN203658471U CN203658471U CN201320725148.2U CN201320725148U CN203658471U CN 203658471 U CN203658471 U CN 203658471U CN 201320725148 U CN201320725148 U CN 201320725148U CN 203658471 U CN203658471 U CN 203658471U
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Abstract
The utility model relates to an interference resisting technology in ground resistance testing, and particularly relates to a power frequency interference suppressing device for testing the ground resistance. The structural key points are that the power frequency interference suppressing device comprise a sine-wave oscillation module, a phase shifting and amplitude modulating module, a power driving and boosting module which are electrically connected in sequence and a power supply module connected with the three modules, wherein the phase shifting and amplitude modulating module comprises a plurality of phase shifting units and an amplitude modulating unit. The interference suppressing device provided by the utility model is different from an existing filtering mode, eliminates power frequency interferences by adopting a compensation method, produces power frequency 50Hz sine-wave signals by using independent power supply oscillation, and carries out phase shifting and amplitude modulation processing on the signals so as to compensate power frequency interference voltage. The power frequency interference suppressing device can well eliminate power frequency interference voltage within a peak range of 0-120V, and ensures good test precision. The interference suppressing device is simple in structure, convenient to control and good in interference resisting effect.
Description
Technical field
The utility model relates to a kind of selectivity penalty method test shaft tower and connects the Anti-Jamming Technique in stake resistance, particularly a kind of powerline pole tower ground resistance test power frequency interference rejection unit.
Background technology
China is with a varied topography various, and mountain region area accounts for 69% of national land area, and most overhead line structures set up along mountain region, soil resistivity is generally higher, difficulty of construction is large, causes grounding resistance relatively large, and circuit happens occasionally because of the counterattack trip event that lightning withstand level deficiency causes.Therefore, how carrying out accurately and efficiently the test of overhead line structures stake resistance, obtain the true lightning withstand level of shaft tower, is the key that advances transmission line of electricity Thunder Protection.
At present, when pole tower ground resistance is measured in electric system, the portable alien frequencies device of general employing is tested, as Fig. 1.R in figure
jfor the self-resistance of pole and tower foundation ground connection, R
efor the self-resistance of artificial earthing's ray, R
hfor the mutual resistance between foundation grounding and artificial earthing, R
tthe contact resistance of tower body and lightning conducter.Due to mutual resistance R
hexistence, conventionally test method will be subject to the impact of the overhead ground wire being connected with shaft tower to some extent, test result is often less than normal.
The problem existing based on conventionally test method, Fujian Province has proposed selectivity penalty method in 2002, and its test philosophy figure is as shown in Figure 2.When test, measure required necessary downlead except retaining one, all the other down conductors all will be dismantled or isolation processing.In figure, CT(split-core type meter) be the branch current for responding to artificial earthing's device downlead, because all the other down conductors of shaft tower are dismantled, therefore the electric current of this branch road is the branch current of whole artificial earthing's device.Therefore, adopt after selectivity penalty method, can obtain separately the corresponding grounding resistance of CT branch road (is R
e), and I
jTthe resistance of branch road is left out.As seen from the figure, R
htwo ends are equipotential, there is no the electric current R that flows through
htherefore, R
hexistence just can not affect test result.
Current alien frequencies earth resistance tester on the market all possesses selectivity penalty method (single split-core type meter method) test function; but these testers are considered the portability of its use more; its built-in variable-frequency power sources capacity is generally less; and the inner single-chip microcomputer that adopted more; the light current treatment circuits such as DSP; the ability that its anti-power frequency is disturbed is more limited, and for the requirement of the protection to instrument and measuring accuracy, the power frequency interference voltage that proving installation generally can detect it arranges limit.Like this, carrying out selectivity compensation model while testing, if pole tower ground resistance value is higher, its interference voltage tends to exceed instrument limit value is set, and causes carrying out proper testing.And along with the increase of system, the raising of line voltage distribution grade, electromagnetic environment becomes increasingly complex, and the interference of the test to pole tower ground resistance is increasing, the higher requirement that measuring technology is proposed.
Summary of the invention
The purpose of this utility model be according to the deficiencies in the prior art part provide a kind of anti-power frequency interference effect good, control convenient, simple to operate pole tower ground resistance test power frequency interference rejection unit.
The purpose of this utility model realizes by following approach:
Earth resistance power frequency interference rejection unit, its structural feature is, includes sine-wave oscillation module, phase-shifting amplitude-modulated module and power drive and the boost module of sequentially electrical connection, and the power module being connected with above-mentioned three modules respectively; Wherein phase-shifting amplitude-modulated module includes the phase-shifting unit and the AM unit that are made up of a plurality of phase shift links;
Each phase shift link comprises that the first feedback resistance, the second feedback resistance, phase modulation resistance, phase modulation electric capacity and phase modulation amplifier form; The output terminal of sine-wave oscillation module is connected to the inverting input of phase modulation amplifier, the in-phase input end that process phase modulation resistance is connected to phase modulation amplifier through the first feedback resistance respectively, the in-phase input end of phase modulation amplifier is via phase modulation capacity earth, and the output terminal of phase modulation amplifier is connected to its inverting input by the second feedback resistance; A plurality of phase shift links connect and compose phase-shifting unit step by step;
AM unit includes amplitude modulation potentiometer and buffering amplifier, the output terminal of phase shift link is by amplitude modulation potentiometer ground connection, the adjustable side of the potentiometer of amplitude modulation is simultaneously connected to the in-phase input end of buffering amplifier, the output terminal of buffering amplifier provides a feedback point to be connected with its inverting input, and the output terminal of this buffering amplifier is connected with power drive and boost module simultaneously.
Concrete:
Phase-shifting unit is made up of basic phase shift link, adopt the mode of multi-stage cascade, optimum is 3 grades of cascade systems, front two-stage form maximum 330 ° can phase shift range, adopt multilayer linked switch to carry out coarse adjustment, every grade adjustable 30 °, rear one-level adopts adjustable resistance, maximum can realize 35 ° of Continuous phase shiftings, and three-stage cascade can be realized 360 ° of continuous adjustable phases.
The utility model is to be applied in pole tower ground resistance selectivity compensation test method, and power frequency is disturbed and carried out reverse compensation, guarantees that testing tool can normally be worked, measuring accuracy is unaffected.The problem of the poor anti jamming capability in use occurring for alien frequencies earth resistance tester, the utility model compensation source of connecting in voltage pole test loop, disturbs and eliminates power frequency.This compensation source utilizes independent current source vibration to generate the sinusoidal signal of power frequency 50Hz, and this signal is carried out to phase shift and amplitude modulation processing compensates power frequency interference voltage.Its principle of work is: utilize the sine-wave oscillation module self-sustained oscillation generation power frequency sinusoidal signal identical with system frequency, this signal is input to phase-shifting amplitude-modulated module, carry out phase place and range-adjusting, the output of phase-shifting amplitude-modulated module is connected to power drive and boost module, signal is carried out to power amplification and the output of boosting, interference voltage is compensated, improve power frequency antijamming capability and the measuring accuracy of selectivity earthing test device.
Wherein phase-shifting amplitude-modulated module is nucleus module, and effect is that the power frequency 50Hz signal that offset of sinusoidal ripple oscillation module produces carries out phase place and range-adjusting, enables to realize the phase compensation of power frequency interference signals amplitude.Phase-shifting unit can determine by the transport function of calculating its each phase-shifting unit, and the phase deviation of the relative input signal of output signal is the function of phase modulation resistance, and amplitude offset is zero.A phase shift link theory can phase shift range be 0～180 °.For realizing continuous adjustable phase within the scope of 360 °, phase-shifting unit takes the mode of multiple above-mentioned phase shift link cascade to increase phase shift range, after AM unit is placed on to the cascade of multistage phase shift link, carries out overall amplitude control.The cascade of three grades of phase shift links is also connected the rear phase-shifting amplitude-modulated module forming with amplitude modulation link.
The utility model proposes a kind of interference rejection unit being applied in the test of selectivity penalty method, exchange device can be good elimination 0～120V peak value within the scope of power frequency interference voltage, while solving the test of selectivity penalty method, because power frequency interference voltage is excessive, the problem that causes instrument normally to work, and ensure the measuring accuracy that it is good.Described interference rejection unit is simple in structure, and it is convenient to control, and anti-jamming effectiveness is good, and measuring accuracy is also just high.
The utility model can further be specially:
Sine-wave oscillation module is a kind of Wen's bridge self-maintained circuit.
The sinusoidal wave module that occurs adopts hardware filtering method, between tester E, S two-stage, obtains undesired signal V
in1, by middle low-pass filtering loop, output V
outto phase-shifting amplitude-modulated link, thereby the frequency that realizes the two is followed in real time.
Described Wen's bridge self-maintained circuit is classical self-maintained circuit, and the self-oscillatory frequency stabilization of calculative determination by frequency selection network, at power frequency 50Hz, adopts high precision current potential device in frequency selection network, and the certain limit that realizes output frequency is adjustable.Employing is in series with the branch road of diode as negative feedback branch road, utilizes the dynamic resistance of diode to realize the fixed ampllitude of output.In negative feedback branch road, adopt a potentiometer, for the starting of oscillation of circuit.Treat that circuit can stablize starting of oscillation, regulate after output frequency and output amplitude, in fixing sine-wave oscillation module for potentiometer and the frequency modulation potentiometer of starting of oscillation, to stablize frequency and the amplitude of output signal.
Power drive and boost module include power drive link and the link of boosting, and the circuit design that wherein power drive is alleviated is that integrated power amplifies form, and the link of boosting is made up of step-up transformer.
The power amplifier of power drive link adopts integrated amplifier chip to form.After each functional module is connected, utilize step-up transformer to amplify output.The effect of power drive and boost module is to improve carrying load ability and the output amplitude in compensation source, comprise power drive link and the link of boosting, the signal of phase-shifting amplitude-modulated module output is carried out power amplification by power drive link, the link of boosting adopts basic step-up transformer to realize, and drafting no-load voltage ratio is 1:13.
In sum, the utility model adopts the method for Contrary compensation that power frequency is disturbed and suppressed, and has the following advantages and good effect:
(1) using selectivity penalty method to carry out in pole tower ground resistance test job, adopt compensation method to disturb and compensate and eliminate the power frequency in test environment, improved the power frequency antijamming capability of alien frequencies earthing test device, and ensured measuring accuracy.
(2) adopted 360 ° within the scope of the continuous Method and circuits of adjustable phase, can realize the good compensation of power frequency interference signals, in actual test, compensation precision is in 1V.
(3) adopt power drive and booster circuit, made the fan-out capability of power frequency interference rejection unit reach 0～120V peak value scope, greatly improved the power frequency antijamming capability of alien frequencies earthing test device.
(4) adopted amplitude adjustment control circuit, the flexible in size that power frequency interference rejection unit can be disturbed according to power frequency in actual environment is selected compensation point, and it is convenient to control.
(5) adopt independent current source, make power frequency interference rejection unit to depart from power frequency supply and carry out execute-in-place and control, easy to carry.
Brief description of the drawings
Figure 1 shows that three electrode method conventionally test key wiring diagram described in the utility model background technology.
Figure 2 shows that selectivity compensation model key wiring diagram described in the utility model background technology.
Fig. 3 is the framed structure schematic diagram of earth resistance power frequency interference rejection unit described in the utility model embodiment.
Figure 4 shows that the schematic circuit structural representation of phase-shifting amplitude-modulated module described in the utility model: the phase-shifting unit in circuit is the cascade of multiple phase shift link, and this schematic diagram only provides the electrical block diagram that last phase shift link is connected with AM unit.
Figure 5 shows that structural representation when earth resistance power frequency interference rejection unit described in the utility model is applied to selectivity penalty method earth loop impedance test.
Below in conjunction with embodiment, the utility model is described further.
Embodiment
Most preferred embodiment:
With reference to accompanying drawing 3, earth resistance power frequency interference rejection unit, adopt reverse compensation method to realize power frequency and disturb inhibition, include sine-wave oscillation module, phase-shifting amplitude-modulated module and power drive and the boost module of sequentially electrical connection, and the power module being connected with above-mentioned three modules respectively; Wherein phase-shifting amplitude-modulated module includes the phase-shifting unit and the AM unit that are made up of a plurality of phase shift links.
With reference to accompanying drawing 4, each phase shift link comprises that the first feedback resistance R1, the second feedback resistance R2, phase modulation resistance R 3, phase modulation capacitor C and phase modulation amplifier P1 form; The output terminal of sine-wave oscillation module, i.e. the input end V of phase-shifting amplitude-modulated module
inbe connected to the inverting input of phase modulation amplifier P1, the in-phase input end that process phase modulation resistance R 3 is connected to phase modulation amplifier P1 through the first feedback resistance R1 respectively, the in-phase input end of phase modulation amplifier P1 is via phase modulation capacitor C ground connection, and the output terminal of phase modulation amplifier P1 is connected to its inverting input by the second feedback resistance R2; 3 phase shift links as above connect and compose phase-shifting unit step by step;
AM unit includes amplitude modulation potentiometer R4 and buffering amplifier P2, the output terminal that phase-shifting unit is last, be that the output terminal of phase modulation amplifier P1 is by amplitude modulation potentiometer R4 ground connection, the adjustable side of the potentiometer of amplitude modulation simultaneously R4 is connected to the in-phase input end of buffering amplifier P2, the output terminal of buffering amplifier P2 provides a feedback point to be connected with its inverting input, the output terminal V of this buffering amplifier P2 simultaneously
outbe connected with power drive and boost module.Described amplifier refers to operational amplifier.
The effect of described sine-wave oscillation module is to produce by self-sustained oscillation the power frequency 50Hz sinusoidal signal of amplitude stability frequency stabilization, for phase-shifting amplitude-modulated module provides stable input.
The Wen bridge self-maintained circuit of the design of described sine-wave oscillation module based on classical, the self-oscillatory frequency stabilization of calculative determination by frequency selection network is at power frequency 50Hz, in frequency selection network, adopt high precision current potential device, the certain limit that realizes output frequency is adjustable.Employing is in series with the branch road of diode as negative feedback branch road, utilizes the dynamic resistance of diode to realize the fixed ampllitude of output.In negative feedback branch road, adopt a potentiometer, for the starting of oscillation of circuit.Treat that circuit can stablize starting of oscillation, regulate after output frequency and output amplitude, in fixing sine-wave oscillation module for potentiometer and the frequency modulation potentiometer of starting of oscillation, to stablize frequency and the amplitude of output signal.
The effect of phase-shifting amplitude-modulated module is that the power frequency 50Hz signal that offset of sinusoidal ripple oscillation module produces carries out phase place and range-adjusting, enables to realize the phase compensation of power frequency interference signals amplitude.
The elementary cell of phase-shifting amplitude-modulated module comprises phase shift link and amplitude modulation link, it designs respectively based on capacitance-resistance phase shift network and potentiometer voltage divider principle: can determine by calculating its transport function, the phase deviation of the relative input signal of output signal is the function of phase modulation resistance R 3, and amplitude offset is zero.A phase shift link theory can phase shift range be 0～180 °.For realizing continuous adjustable phase within the scope of 360 °, take the mode of 3 above-mentioned phase-shifting unit cascades to increase phase shift range, after amplitude modulation link is placed on to the cascade of three grades of phase shift links, carry out overall amplitude control.The output of phase shift link is carried out voltage division processing by amplitude modulation potentiometer R4, and the buffer stage consisting of buffering amplifier P2 is exported, and by regulating the intrinsic standoff ratio of amplitude modulation potentiometer R4, the amplitude that realizes signal regulates.The cascade of three grades of phase shift links is also connected the rear phase-shifting amplitude-modulated module forming with amplitude modulation link.
The effect of power drive and boost module is to improve carrying load ability and the output amplitude in compensation source, comprises power drive link and the link of boosting.The signal of phase-shifting amplitude-modulated module output is carried out power amplification by power drive link, and its circuit design is that integrated power amplifies form, and the integrated power amplification chip of employing is TDA2030A, and physical circuit is drafted the typical application circuit into TDA2030A.The link of boosting adopts basic step-up transformer to realize, and drafting no-load voltage ratio is 1:13.
The effect of power module is to provide power supply and potential reference point for sine-wave oscillation module, phase-shifting amplitude-modulated module, power drive and boost module.Consider field demand, draft as ± universal the chargeable lithium cell of 12V, adopt linear voltage stabilization chip 7809 and 7909 to carry out voltage stabilizing.
Described earth resistance power frequency interference rejection unit being applied as in alien frequencies method earth loop impedance test:
With reference to accompanying drawing 5, the test lead of alien frequencies earthing test device is connected to grounded screen 2 by earthing pole 1; Voltage output end is connected with described earth resistance power frequency interference rejection unit, then via voltage pole 3 ground connection; Current output terminal is via the electric current utmost point 4 ground connection.When use, adjusted according to the phase place of undesired signal and amplitude by earth resistance power frequency interference rejection unit, and compensate power frequency interference signals, eliminate undesired signal, reach jamproof object.
It is same as the prior art that the utility model is not stated part.
Claims (3)
1. earth resistance power frequency interference rejection unit, is characterized in that, includes sine-wave oscillation module, phase-shifting amplitude-modulated module and power drive and the boost module of sequentially electrical connection, and the power module being connected with above-mentioned three modules respectively; Wherein phase-shifting amplitude-modulated module includes the phase-shifting unit and the AM unit that are made up of a plurality of phase shift links;
Each phase shift link comprises that the first feedback resistance, the second feedback resistance, phase modulation resistance, phase modulation electric capacity and phase modulation amplifier form; The output terminal of sine-wave oscillation module is connected to the inverting input of phase modulation amplifier, the in-phase input end that process phase modulation resistance is connected to phase modulation amplifier through the first feedback resistance respectively, the in-phase input end of phase modulation amplifier is via phase modulation capacity earth, and the output terminal of phase modulation amplifier is connected to its inverting input by the second feedback resistance; A plurality of phase shift links connect and compose phase-shifting unit step by step;
AM unit includes amplitude modulation potentiometer and buffering amplifier, the output terminal of phase shift link is by amplitude modulation potentiometer ground connection, the adjustable side of the potentiometer of amplitude modulation is simultaneously connected to the in-phase input end of buffering amplifier, the output terminal of buffering amplifier provides a feedback point to be connected with its inverting input, and the output terminal of this buffering amplifier is connected with power drive and boost module simultaneously.
2. earth resistance power frequency interference rejection unit according to claim 1, is characterized in that, sine-wave oscillation module is a kind of Wen's bridge self-maintained circuit.
3. earth resistance power frequency interference rejection unit according to claim 1, it is characterized in that, power drive and boost module include power drive link and the link of boosting, the circuit design that wherein power drive is alleviated is that integrated power amplifies form, the integrated power amplification chip adopting is TDA2030A, and the link of boosting is made up of step-up transformer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320725148.2U CN203658471U (en) | 2013-11-18 | 2013-11-18 | Power frequency interference suppressing device for testing ground resistance |
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| CN201320725148.2U CN203658471U (en) | 2013-11-18 | 2013-11-18 | Power frequency interference suppressing device for testing ground resistance |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103645384A (en) * | 2013-11-18 | 2014-03-19 | 国家电网公司 | Grounding resistor test power frequency interference inhibition apparatus |
| CN112285426A (en) * | 2020-10-29 | 2021-01-29 | 广东电网有限责任公司电力科学研究院 | Grounding resistance testing method and system of tower grounding device and terminal equipment |
| CN112285425A (en) * | 2020-10-29 | 2021-01-29 | 广东电网有限责任公司电力科学研究院 | Grounding resistance calculation method and device of tower grounding device and terminal equipment |
-
2013
- 2013-11-18 CN CN201320725148.2U patent/CN203658471U/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103645384A (en) * | 2013-11-18 | 2014-03-19 | 国家电网公司 | Grounding resistor test power frequency interference inhibition apparatus |
| CN103645384B (en) * | 2013-11-18 | 2018-11-06 | 国家电网公司 | Earth resistance Hz noise restraining device |
| CN112285426A (en) * | 2020-10-29 | 2021-01-29 | 广东电网有限责任公司电力科学研究院 | Grounding resistance testing method and system of tower grounding device and terminal equipment |
| CN112285425A (en) * | 2020-10-29 | 2021-01-29 | 广东电网有限责任公司电力科学研究院 | Grounding resistance calculation method and device of tower grounding device and terminal equipment |
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Granted publication date: 20140618 Effective date of abandoning: 20181106 |