A kind of earth-return circuit detection method of voltage whole station one point earthTechnical field
A kind of earth-return circuit the invention belongs to power network detection technique field, more particularly to voltage whole station one point earth is detectedMethod.
Background technology
Power system voltage loop N line whole station one point earths are a kind of very typical connection types, especially for doubleBus wiring plant stand and 500kV websites.But the mode of connection have one it is very big the drawbacks of, be exactly because universal meter resistance grade outputImpedance comparison is small, easily causes two points ground fault, leads to not measure voltage using universal meter resistance grade judge whether to have connectGround, especially for enlarging, reconstruction project, if once voltage N lines imperfect earth cannot find, belong to long-standing problem secondary returningThe blind area of road inspection；Simultaneously false protection is repeatedly caused in power industry internal system.Only just sent out in extra high voltage system in recent yearsRaw multiple, existing method can only obtain empirical value and speculate Grounding by voltage measurement, not have accurate method inspection.
Therefore, a kind of method that can reliably and securely judge Earthing Reliability is needed badly in the industry.
The content of the invention
In view of the shortcomings of the prior art, the present invention provides a kind of earth-return circuit inspection of voltage circuit N lines whole station one point earthSurvey method.
The present invention is to solve above-mentioned technical problem by the following technical solutions：A kind of voltage circuit N lines whole station oneThe earth-return circuit detection method of point ground connection, including：
1st, the signal generating unit of detecting instrument sends digital current signal to the tested point of earth mat, and detection is flow back into by earth matInstrument, signal is gathered by the signal gathering unit of detecting instrument, and the data signal that the microprocessor contrast of detecting instrument sends is electricStream and collection signal, if sending inconsistent with the signal of collection, the earth point imperfect earth, if sending the signal one with collectionCause, then earth point ground connection is good, and touching display screen module by detecting instrument shows；The ratio of receiving and transmitting signal uniformityGood and external environment condition the annoyance level of ground connection can be reflected；
2nd, the resistance value of measure loop in detecting instrument is adjusted by adjusting the potentiometer of detecting instrument, control sends data signalThe size of electric current controls the size of external detection ground contact resistance, so as to avoid communication failure, external detection ground contactResistance is generally tens ohm, if exceeding this numerical value, can cause communication failure；The resistance value one of measure loop in detecting instrumentAs reach several kilohms, output impedance is larger, solves because universal meter output impedance is smaller causes two points ground fault, it is impossible to useUniversal meter resistance grade measurement voltage whether grounded defect；
3rd, stop sending digital current signal, high level signal is sent to tested point, detecting instrument is flow back into by earth mat, to inspectionThe resistance both end voltage for surveying instrument internal measure loop is judged, if tested point is formed with earth mat being reliably connected, forms straightLogical circulation road, close to normal reference voltage level, then tested point ground connection is good for the resistance both end voltage；If tested point and earth matDisconnect and exist larger parasitic capacitance, although step 1,2 communications are normal, but can not form DC channel, can't detect voltage,The then tested point loose contact, the step 3 is avoided because the signal sent in step 1 and 2 belongs to high-frequency signal, due to cableThe influence of parasitic capacitance, when parasitic capacitance reaches certain value, although normal for high-frequency signal communication, but it is actually unable in shapeInto DC channel, detection is interfered, the defect of erroneous judgement.
Further, the detecting instrument also includes signal isolation transmitter unit, and isolation is played a part of to transmission signal,The microprocessor of the detecting instrument is connected with signal generating unit, signal gathering unit and touching display screen module respectively,The signal generating unit is connected with signal isolation transmitter unit.
The microprocessor, for the letter that control signal generating unit sending signal and reception signal sampling unit are collectedNumber, and collection signal to sending signal compares and treats, and result is sent into touching display screen module shows；The signal generating unit, for sending the signals such as digital current signal, high level；Signal isolation transmitter unit, for hairThe signal for going out is isolated；Signal sampling unit, the signal of detecting instrument is input to for gathering, and send the signal to micro-Processor is processed；Touching display screen module, the setting etc. for showing testing result and detecting instrument parameter.
Further, the signal generating unit includes enabling control unit and high-frequency signal generating unit, enables controlUnit connects high-frequency signal generating unit and microprocessor, high-frequency signal generating unit connection signal isolation transmitter unit respectively.
Further, AD conversion unit, Flash memory cell and USART full duplexs are provided with the microprocessor generalThe serial transceiver module of synchronous/asynchronous, and AD conversion unit is connected with signal gathering unit, USART full duplexs universal synchronous/differentSerial transceiver module is walked to be connected with touching display screen module.
Compared with prior art, the earth-return circuit detection side of voltage circuit N lines whole station one point earth provided by the present inventionMethod, with earth mat as communication media, the uniformity of the digital current signal data by judging transmitting-receiving, and by detecting whether shapeJudge whether ground connection is good into complete DC loop voltage；Described earth-return circuit detection method can be quickly and accuratelyGround connection judgement is carried out, solves the problems, such as that cannot measure voltage using universal meter resistance grade judges whether ground connection, greatly reducesBecause of ground wire grounded bad caused false protection, detection difficulty is reduced, reduce the workload of attendant, improve power networkThe level of system safety operation, has significant meaning for the detection of network system.
Brief description of the drawings
In order to illustrate more clearly of technical scheme, embodiment will be described below needed for the accompanying drawing to be usedIt is briefly described, it should be apparent that, drawings in the following description are only one embodiment of the present of invention, general for this areaFor logical technical staff, on the premise of not paying creative work, other accompanying drawings can also be obtained according to these accompanying drawings.
The step of Fig. 1 is a kind of earth-return circuit detection method of voltage circuit N lines whole station one point earth of the invention flowFigure；
Fig. 2 is live earth-return circuit detects schematic diagram of the invention；
Fig. 3 is the equivalent resistance schematic diagram of earth-return circuit detection of the invention；
Fig. 4 is the capacitor equivalent schematic diagram of earth-return circuit detection of the invention.
Specific embodiment
With reference to the accompanying drawing in the embodiment of the present invention, the technical scheme in the present invention is clearly and completely described,Obviously, described embodiment is only a part of embodiment of the invention, rather than whole embodiments.Based in the present inventionEmbodiment, the every other embodiment that those of ordinary skill in the art are obtained on the premise of creative work is not made,Belong to the scope of protection of the invention.
As depicted in figs. 1 and 2, the earth-return circuit detection of voltage circuit N lines whole station one point earth provided by the present invention, surveysPilot is generally the grounding shell of protection device, or N lines, and another test point is generally earth mat nearby, is situated between by communication of earth matMatter forms communication loop, and specific detecting step includes：
1st, the signal generating unit of detecting instrument sends digital current signal to the test point 2 of earth mat, and inspection is flow back into by earth matInstrument is surveyed, signal, the data signal of the microprocessor contrast transmission of detecting instrument are gathered by the signal gathering unit of detecting instrumentElectric current and collection signal, if sending inconsistent with the signal of collection, the earth point imperfect earth, if sending the signal with collectionUnanimously, then earth point ground connection is good, and touching display screen module by detecting instrument shows；
2nd, stop sending digital current signal, high level signal is sent to test point 2, detecting instrument is flow back into by earth mat, it is rightThe resistance both end voltage of detecting instrument inside measure loop is judged, if test point 2 is formed with earth mat being reliably connected, is formedDC channel, the resistance both end voltage is close to normal reference voltage level；If test point 2 disconnects and exists larger with earth matParasitic capacitance, although communication is normal, but can not form DC channel, and detection voltage is zero, then the tested point loose contact.
The equivalent resistance schematic diagram of earth-return circuit detection as shown in Figure 3, resistance R is test point 1 shown in Fig. 2 and test point 2Between the resistance of ground wire line, the signal that the signal generating unit of detecting instrument sends（Including digital current signal and high level）Pass throughResistance R is back to the signal gathering unit of detecting instrument, forms proper communication, when signal is sent for high level, due to resistanceVoltage divider principle, magnitude of voltage U close to reference voltage level VDD, and should be not zero, and represent that ground connection is good；When line resistance R arrives greatly certain valueWhen, due to the excessive critical value for causing communication failure, hindering R come control line by adjusting R1, R2 size of signal code decay, it is to avoidCommunication failure.
The capacitor equivalent schematic diagram of earth-return circuit detection as shown in Figure 4, electric capacity C is test point 1 shown in Fig. 2 and test point 2Between earth cable to the parasitic capacitance of earth mat, because the digital current signal that the signal generating unit of detecting instrument sends belongs toHigh-frequency signal, the signal gathering unit of detecting instrument is back to by electric capacity C, forms proper communication, but electric capacity is to direct currentImpedance is infinitely great, during input high level, does not become DC channel, and voltage U is zero, represent imperfect earth, it is to avoid only logicalCross step 1 to detect, cause the phenomenon of erroneous judgement.
The earth-return circuit detection method of the voltage circuit N line whole station one point earths that the present invention is used, is situated between by communication of earth matMatter, the uniformity of the digital current signal data by judging transmitting-receiving, and to form complete DC loop by detecting whetherWhether voltage is good to judge ground connection；Described earth-return circuit detection method can quickly and accurately carry out ground connection judgement, solutionHaving determined cannot measure the problem that voltage judge whether ground connection using universal meter resistance grade, greatly reduce and bad led because ground wire groundedThe false protection of cause, reduces detection difficulty, reduces the workload of attendant, improves the water of network system safe operationIt is flat, there is significant meaning for the detection of network system.
Above disclosed is only specific embodiment of the invention, but protection scope of the present invention is not limited thereto,Any one skilled in the art the invention discloses technical scope in, can readily occur in change or modification, allShould be included within the scope of the present invention.