CN101635077A - Anti-theft detection method for road lamp cable - Google Patents

Abstract

The invention discloses a street lamp cable anti-theft detection method. Source injection signal frequency, measure the current and voltage output by the current source, find the resonant frequency of the single-phase street lamp circuit, measure the equivalent total capacitance of the street lamp connected to the tested street lamp line and the number of street lamps; if the number of street lamps measured is not equal to the actual If the number of street lamps is large, it is judged that the line cable is stolen, and the stolen point of the street lamp cable is located, and an alarm signal is sent. The method of the invention does not need to add equipment at the end of the cable, and is not affected by the type of transformer and the length of the line. The problem of theft and disconnection alarm.

Description

Anti-theft detection method for road lamp cable

Technical field

The present invention relates to a kind of anti-theft detection method for road lamp cable, the anti-theft detection method for road lamp cable during particularly a kind of road lamp system is turned off the light.

Background technology

Present domestic transitional street lamps cable theft-prevention method mainly contains three kinds: the current method that leaks hunting, electric current and voltage detection method and power carrier method.

Document [Cao Bin, simple analysis cable anti-theft alarm The Application of Technology, industrial control computer, 2009,22 (5)] propose the current method that leaks hunting, between cable end piece and the earth, made an artificial electric leakage, in switch box, detected this leakage current, in case the stolen cut-out of cable then leakage current significantly reduce, judge whether stolen cut-out of cable by leakage current; But be subjected to the influence of leakage current of cable own, this method rate of false alarm height, and can not carry out stolen point and accurately locate.Document [square wave, power cable guard against theft and alarm system, electrotechnics, 2007,30 (1)] has proposed the electric current and voltage detection method, detects the cable current during turning on light, if electric current reduces suddenly, thinks that then cable is stolen; This method is influenced by voltage fluctuation, and antitheft accuracy of detection is poor.More than the road lighting cable antitheft detection of two kinds of methods during can only being used to turn on light, and road lighting cable stolen usually occur in turn off the light during.[opening can for document for this reason, based on the antitheft scheme of power line carrier low-voltage cable, Electronic Testing, 2009,45 (6)] proposed the power carrier method,, the power carrier receiving trap has been installed at cable end piece in cable head emission power carrier signal, if the power carrier device does not receive power carrier signal, then think the stolen cut-out of cable; This method need be installed the carrier wave receiving trap at line end, the cost height, and be subjected to the influence of street lamp electric capacity and electric cable capacitance, the carrier signal decay is big, is difficult to use in the antitheft detection of long cable.

For this reason, domestic urgent need invention high precision, the anti-theft detection method for road lamp cable of high reliability is with the antitheft high precision of road lighting cable during satisfying street lamp and turning off the light, the detection requirement of high reliability.

Summary of the invention

The invention provides a kind of high precision, the anti-theft detection method for road lamp cable of high reliability is applicable to the antitheft detection of road lighting cable during street lamp is turned off the light.

The technical scheme that the present invention solves the problems of the technologies described above may further comprise the steps:

(1) reactor that is L with inductance of a frequency conversion current source series connection, a fixed resistance and a rotary switch insert between street-lighting transformer neutral point and the three-phase low-voltage bus bar, and wherein rotary switch three moving contact a, b, c connect the three-phase low-voltage bus bar of transformer; When measuring beginning, the moving contact of rotary switch is rotated to a moving contact;

(2) the frequency conversion current source is through the frequency conversion current signal of reactor to a constant magnitude of phase bus injection, and the electric current and the voltage phase difference of measuring current source output change and inject signal frequency, find out resonance angular frequency ω ₀Utilize following formula to calculate the measured value of the street lamp quantity of tested public lighting circuit connection:

C in the formula ₀Be the capacitance of single street lamp,

It is right to represent The round number;

(3) if street lamp takeoff value n _SurveyEqual the actual value of test line street lamp quantity, show that the line cord that this tested phase connects is complete, do not have stolenly, the moving contact of rotary switch along a → b → c → a order, is rotated to next moving contact, return step (2);

(4) if described step (2) street lamp takeoff value n _SurveyThe actual value that is not equal to test line street lamp quantity, show that this tested phase institute connection line cable is stolen, operate the street lamp branch switch that this phase bus links to each other, measure the street lamp quantity of every branch road successively one by one, have and only have tested street lamp branch road to connect with tested bus mutually during measurement, (2) measure the street lamp quantity of branch road set by step; If the measured value of branch road street lamp quantity is not equal to the actual value of this branch road street lamp quantity, show that this tested branch cable is stolen, stolen point is positioned at the n that stolen branch road is counted from the head end to the end _SurveySmall cup and n _SurveyBetween+1 street lamp.

2, anti-theft detection method for road lamp cable according to claim 1 is characterized in that: the span of reactor inductance is 5mH～150mH in the described step 1).

Technique effect of the present invention is: need not increase equipment at line end, not influenced by transformer model and line length, have safety, quick and widely applicable advantage has thoroughly solved the difficult problem of cable anti-theft alarm during street lamp is turned off the light.Can accurately determine stolen cable branch road, locate stolen some particular location, error is less than the spacing (being generally 20 meters～50 meters) of two street lamps.

Below in conjunction with accompanying drawing the present invention is made and to further specify.

Description of drawings

Fig. 1 is that cable theft-prevention of the present invention detects wiring diagram.

Fig. 2 is the equivalent circuit diagram that cable theft-prevention of the present invention detects.

Fig. 3 is the process flow diagram that cable theft-prevention of the present invention detects.

Embodiment

Referring to Fig. 1, Fig. 1 implements wiring diagram of the present invention for utilizing cable theft-prevention measuring instrument 3.There is the voltage measurement unit 4 of a frequency conversion current source 5 and a frequency conversion current output signal cable theft-prevention measuring instrument 3 inside.Between inductance of frequency conversion current source 5 series connection be size for the reactor 7 of L, a fixed resistance 6 and rotary switch 2 access street-lighting transformers 1 neutral point and three-phase low-voltage bus bar, wherein three of rotary switch moving contact a, b, c connect the three-phase low-voltage bus bar M of street-lighting transformer respectively _A, M _B, M _CDuring street lamp is turned on light, three-phase breaker K _A, K _B, K _CClosure, the moving contact of rotary switch 2 connect vacant node O, and cable theft-prevention measuring instrument 3 does not carry out the antitheft detection of road lighting cable; During street lamp is turned off the light, three-phase breaker K _A, K _B, K _CDisconnect, the moving contact of rotary switch 2 connects moving contact a, b, c successively, and cable theft-prevention measuring instrument 3 carries out antitheft patrolling and examining to A, B, C uniline respectively.

The equivalent circuit diagram that cable theft-prevention of the present invention detects as shown in Figure 2.According to the inner structure of outer startup high-pressure mercury lamp, when the high-pressure mercury lamp both end voltage is lower than 50V, the street lamp open circuit, the equivalent capacity of single street lamp is C ₀, as measuring the n small cup street lamp of parallel running in the loop, then equivalent capacity is:

C＝nC ₀

During measurement, the frequency conversion current signal of constant magnitude is injected in frequency conversion current signal source 5 to circuit-under-test

Measure the return voltage signal by voltage measurement unit 4

The voltage signal that compares and measures

With the injection current signal

Phase angle difference

Change the injection current signal frequency, when

When value equalled zero, the current signal frequency was the resonance angular frequency ω of street lamp branch road ₀Can get according to resonance principle:

${\mathrm{\ω}}_{0}L=\frac{1}{{\mathrm{\ω}}_{0}C}$

Get by above-mentioned two formulas:

$n=\frac{1}{{\mathrm{\ω}}_0^{2}L{C}_0}$

The round number obtains the measured value of street lamp quantity in the test line:

In the formula It is right to represent

The round number.

Compare and measure value n _SurveyWith the street lamp quantity actual value n that installs in this measurement loop _Real,, illustrate that cable is complete in this measurement loop if both are equal; If both are unequal, then explanation is measured in the loop and the stolen situation of cable occurred.Only comprise the wall scroll branch cable if measure the loop, then stolen point is positioned at the n that stolen branch road is counted from the head end to the end _SurveySmall cup and n _SurveyBetween+1 street lamp.

Measurement process flow diagram of the present invention as shown in Figure 3.Carry out cable theft-prevention during street lamp is turned off the light and patrol and examine,, measure the resonance angular frequency ω of A circuitry phase the moving contact of rotary switch 2 connected node a at first ₀, the street lamp takeoff value n of calculating A circuitry phase _Survey, and with the street lamp quantity actual value n of A circuitry phase _RealRelatively.If both equate that illustrate that cable is complete in the A circuitry phase, rotary switch rotates in proper order by a → b → c → a successively, detects B circuitry phase, C circuitry phase successively, detects the A circuitry phase again, successively cycle detection.If the street lamp takeoff value n of detected circuitry phase _SurveyActual value n with this detected circuitry phase street lamp quantity _RealUnequal, illustrate that this detected phase cable is stolen, the stolen cut-out of cable appears in this circuitry phase, and next step carries out stolen branch cable and detects and stolen point location.

When stolen branch cable detects, at first disconnect all branch switchs that stolen phase bus links to each other.Closed then article one branch switch, the resonance frequency omega of measurement article one branch road ₀, utilize above-mentioned formula to calculate the street lamp takeoff value n of tested branch road _SurveyIf the street lamp quantity detected value n of tested branch road _SurveyActual value n with tested branch road street lamp quantity _RealEquate, illustrate that tested branch cable is complete, disconnect tested branch switch,, detect next branch road by closed next branch switch of branch cable number order, until all branch cable that stolen phase bus links to each other detected intact till.If the street lamp takeoff value n of tested branch road _SurveyActual value n with this tested branch road street lamp quantity _RealUnequal, illustrate that this branch road is the stolen branch road of cable, the stolen n that from the head end to the end, counts at tested branch road _SurveySmall cup and n _SurveyBetween+1 street lamp, write down the numbering and the position of failure point of tested branch cable; Disconnect tested branch switch,, detect next branch road by closed next branch switch of number order, until all branch cable that stolen phase bus links to each other detected intact till.Send stolen alerting signal at last, and show all stolen some positions.

In order to verify the feasibility of anti-theft detection method for road lamp cable described in the invention, by circuit design shown in Figure 1 the test macro of a stolen detection of road lighting cable, include 14 110W high-pressure mercury lamps, switch is installed in segmentation in cable, disconnect the stolen cut-out of dummycable with switch, respectively to stolen o'clock of detection line cable between the 3rd～the 4th street lamp, stolen o'clock between the 5th～the 6th street lamp, stolen o'clock between the 8th～the 9th street lamp, stolen o'clock between the 11st～the 12nd street lamp and do not have stolen five kinds of situations and detect.Testing result is as shown in table 1, wherein δ _nExpression street lamp takeoff error.

Table 1

As can be seen from Table 1: whether stolen detection is correct for road lighting cable, and stolen some position probing is accurate, street lamp takeoff error delta _nBe 0.1 to the maximum, can satisfy the industry spot service requirement fully; Shown that this inventive method can accurately determine stolen some position, thoroughly solved the difficult problem of the stolen break alarm of line cord during road lamp system is turned off the light.

Claims (2)

1. A street light cable anti-theft detection method is characterized in that it comprises the steps: (1) Connect a variable frequency current source in series with a reactor with an inductance of L, a fixed resistor and a rotary switch between the neutral point of the street lamp transformer and the three-phase low-voltage bus, where the rotary switch has three moving contacts a, b , c is connected to the three-phase low-voltage busbar of the transformer; when the measurement starts, turn the moving contact of the rotary switch to a moving contact; (2) The variable frequency current source injects a constant variable frequency current signal into a phase bus through the reactor, measures the current and voltage phase difference output by the current source, changes the frequency of the injected signal, and finds out the resonant angular frequency _ω0 ; use the following formula Calculate the measured value of the number of street lights connected to the street light line under test:

In the formula, C ₀ is the capacitance value of a single street lamp,

express yes

round to an integer; (3) If the _measured value n of the number of street lamps is equal to the actual value of the number of street lamps on the tested line, it indicates that the line cable connected to the measured phase is complete and has not been stolen. Move the moving contact of the rotary switch along a→b→c→ a sequence, rotate to the next moving contact, and return to step (2); (4) If the _measured value n of the number of street lamps in the step (2) is not equal to the actual value of the measured line street lamp quantity, it indicates that the line cable connected to the measured phase is stolen, and the street lamp branch switch connected to the phase bus is operated. Measure the number of street lamps in each branch one by one in turn. During the measurement, only the measured street lamp branch is connected to the measured phase bus, and measure the number of street lamps in the branch according to step (2); if the measured value of the number of branch street lamps is not Equal to the actual value of the number of street lamps in the branch, it indicates that the cable of the branch under test is stolen, and the stolen point is between the nth _measurement and the _nth +1 streetlight counted from the beginning to the end of the stolen branch. 2. The anti-theft detection method for street lamp cables according to claim 1, characterized in that: in the step 1), the value range of the reactor inductance is 5mH-150mH.

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