CN202886514U - Direct current (DC) system grounding detector - Google Patents
Direct current (DC) system grounding detector Download PDFInfo
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- CN202886514U CN202886514U CN 201220600166 CN201220600166U CN202886514U CN 202886514 U CN202886514 U CN 202886514U CN 201220600166 CN201220600166 CN 201220600166 CN 201220600166 U CN201220600166 U CN 201220600166U CN 202886514 U CN202886514 U CN 202886514U
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Abstract
The utility model relates to a direct current (DC) system grounding detector which comprises a host machine and a plurality of branch detection modules, wherein the host machine is internally provided with a main processor and an ultralow frequency signal source; the main processor comprises a singlechip; the ultralow frequency signal source consists of a No. 1 ultralow frequency signal generator, a No. 1 digital/ analog (D/ A) converter, a No. 1 power amplifier and a No. 1 feed isolator; each branch detection module consists of an analog selection switch, a signal amplifier, a pre-filter, a phase comparator, a post-filter, a No. 1 analog/ digital (A/ D) converter and a co-processor; the host machine is internally provided with a bus coupler detection module and a bus insulation detection module; the bus coupler detection module consists of a No. 2 ultralow frequency signal generator, a No. 2 D/ A converter, a No. 2 power amplifier, a sampling circuit and a No. 2 feed isolator; and the bus insulation detection module consists of a balanced bridge, an unbalanced bridge, a No. 3 A/ D converter, a No. 4 A/ D converter and a selector switch. The DC system grounding detector is an intelligent monitoring instrument capable of improving the power grid running safety and the automatic management level.
Description
Technical field
The utility model relates to the detecting instrument that the power departments such as generating plant, transformer station, power supply station use, and specifically, is a kind of D. C. system earthing detector.
Background technology
The existing straight-flow systems of power department such as generating plant, transformer station, power supply station have again AC system, complex circuit, there is potential faults, sometimes because manual operation causes, be that line fault causes sometimes, need long term monitoring, in case abnormal conditions appear in circuit, in time take measures, the assurance system normally moves, safety in production, for straight-flow system, need the long term monitoring index to comprise:
Monitor straight-flow system positive and negative busbar voltage-to-ground, positive and negative busbar insulation against ground resistance, bus mother, loop insulation and patrol and examine grounding resistance,
In the prior art, the function of D. C. system earthing detector is comparatively single, and a common detector can only be finished a kind of measuring ability, and exist wrong report, fail to report, the drawback such as polling rate is slow, wiring is too much, automatization level is low.Therefore, be badly in need of a kind of intellectual monitoring instrument of research and development, to improve safe operation of electric network and automatic management level.
The utility model content
The purpose of this utility model provides a kind of D. C. system earthing detector, integrate multiple measuring ability, has the function that monitoring straight-flow system positive and negative busbar voltage-to-ground, positive and negative busbar insulation against ground resistance, bus mother, bus exchange over the ground interference voltage, loop insulation and patrol and examine grounding resistance, reliability is high, applied widely, polling rate is fast, wiring is simple, automatization level is high, is a kind of intellectual monitoring instrument that improves safe operation of electric network and automatic management level.
For achieving the above object, the utility model is by the following technical solutions:
A kind of D. C. system earthing detector, consisted of by main frame and a plurality of branch road detection module, the structure of each branch road detection module is identical, it is characterized in that: be provided with primary processor and ultra-low frequency signal source in the described main frame, primary processor is made of single-chip microcomputer, the ultra-low frequency signal source is by a Signal Generator of Ultra-low Frequency, a digital to analog converter, a power amplifier, presenting isolator for No. one forms, the square-wave signal output port of a Signal Generator of Ultra-low Frequency is connected with the input end of a digital to analog converter, the output terminal of a digital to analog converter is connected with the input end of a power amplifier, the output terminal of a power amplifier is connected with the input end of presenting isolator for No. one, the output terminal of presenting isolator for No. one is connected with the negative terminal of bus, described branch road detection module is by the analog selection switch, signal amplifier, the prime wave filter, phase comparator, the rear class wave filter, an analog to digital converter, coprocessor forms, the input end of analog selection switch is connected with mutual inductor, mutual inductor is enclosed within on the branch road loop, the output terminal of analog selection switch is connected with the input end of signal amplifier, the output terminal of signal amplifier is connected with the input end of prime wave filter, the output terminal of prime wave filter is connected with the input end of phase comparator, the output terminal of phase comparator is connected with the input end of rear class wave filter, the output terminal of rear class wave filter is connected with the input end of an analog to digital converter, No. one the analog to digital converter output terminal is connected with the I/O port of coprocessor, the communication port of coprocessor is connected with the communication port of primary processor by level transferring chip, thereby realize communicating by letter between coprocessor and the primary processor, the communication port of primary processor also is connected with the communication port of a Signal Generator of Ultra-low Frequency, for Signal Generator of Ultra-low Frequency provides the steering order signal, the synchronous signal output end mouth of Signal Generator of Ultra-low Frequency is connected with phase comparator in the branch road detection module.
Also be provided with the mother detection module in the described main frame, the mother detection module is by No. two Signal Generator of Ultra-low Frequency, No. two digital to analog converters, No. two power amplifiers, sample circuit and present isolator for No. two and form, the square-wave signal output port of No. two Signal Generator of Ultra-low Frequency is connected with the input end of No. two digital to analog converters, the output terminal of No. two digital to analog converters is connected with the input end of No. two power amplifiers, the output terminal of No. two power amplifiers be connected with the input end of presenting isolator for No. two through over-sampling circuit, the output terminal of presenting isolator for No. two is connected with the negative terminal of bus, the output terminal of sample circuit is connected with the input end of No. two analog to digital converters, the output terminal of No. two analog to digital converters is connected with the sampled voltage input port of No. two Signal Generator of Ultra-low Frequency, the communication port of No. two Signal Generator of Ultra-low Frequency is connected with the communication port of primary processor, send the mother detection signal to primary processor, receive simultaneously the steering order signal that primary processor is sent.
Also be provided with the bus insulation detection module in the described main frame, the bus insulation detection module is by balanced bridge, unbalanced bridge, No. three analog to digital converters, No. four analog to digital converters and change-over switch consist of, the input end of balanced bridge is connected with negative terminal with the anode of bus, the output terminal of balanced bridge is connected with the input end of No. three analog to digital converters, the output terminal of No. three analog to digital converters is connected with the sampled voltage input port of primary processor, the input end of unbalanced bridge is connected with negative terminal with the anode of bus through change-over switch, the output terminal of unbalanced bridge is connected with the input end of No. four analog to digital converters, and the output terminal of No. four analog to digital converters is connected with the sampled voltage input port of primary processor.
Described change-over switch is made of relay.
The described isolator of presenting for No. is made of choking coil and coupling capacitance series connection.
Also be provided with in the described main frame and exchange the interference voltage detection module, exchanging the interference voltage detection module is comprised of coupled circuit, rectification circuit, filtering circuit, No. five analog to digital converters, the input end of coupled circuit is connected with bus, the output terminal of coupled circuit is connected with the input end of rectification circuit, the output terminal of rectification circuit is connected with the input end of filtering circuit, the output terminal of filtering circuit is connected with the input end of No. five analog to digital converters, and the output terminal of No. five analog to digital converters is connected with the sampled voltage input port of primary processor.
Innovation of the present utility model is:
This instrument adopts many CPU, modularization, distributed technology and structural design.Each branch road detection module can detect 16 duplexures, and a main frame can a plurality of branch road detection modules of arbitrary extension.Thereby at multinomial technical new breakthroughs that had such as reliability, applicability, extendabilities, successfully having solved the drawbacks such as present DC earthing pick-up unit exists wrong report, fails to report, polling rate is slow, wiring is too much, installation and maintenance are difficult, is a kind of intellectual monitoring instrument that improves safe operation of electric network and automatic management level.Be widely used in generating plant and transformer station, it has the function that monitoring straight-flow system busbar voltage, positive and negative busbar voltage-to-ground, positive and negative busbar insulation against ground resistance, bus mother, bus exchange over the ground interference voltage, loop insulation and patrol and examine the real-time statuss such as grounding resistance.
Description of drawings
Fig. 1 is the schematic diagram of the utility model embodiment one.
Fig. 2 is the circuit diagram of branch road detection module among Fig. 1.
Fig. 3 is the circuit diagram of ultra-low frequency signal source and mother detection module.
Fig. 4 is bus insulation detection module and the circuit diagram that exchanges the interference voltage detection module.
Fig. 5 is the schematic diagram of the utility model embodiment two.
Embodiment
Please refer to Fig. 1, Fig. 2, Fig. 3, the utility model is a kind of D. C. system earthing detector, is made of main frame and a plurality of branch road detection module, and the structure of each branch road detection module is identical, is provided with primary processor and ultra-low frequency signal source in the main frame,
Primary processor is that the single-chip microcomputer of W78E58 consists of by model, the ultra-low frequency signal source is by a Signal Generator of Ultra-low Frequency, a digital to analog converter, a power amplifier, presenting isolator for No. one forms, Signal Generator of Ultra-low Frequency is that the single-chip microcomputer of AT89C2051 consists of by model, digital to analog converter is that the analog-digital chip of DAC0832 model consists of by model, No. one power amplifier is made of power tube, presenting isolator for No. one is made of choking coil L1 and coupling capacitance C1 series connection, the square-wave signal output port of a Signal Generator of Ultra-low Frequency is connected with the input end of a digital to analog converter, the output terminal of a digital to analog converter is connected with the input end of a power amplifier, the output terminal of a power amplifier is connected with the input end of presenting isolator for No. one, the output terminal of presenting isolator for No. one is connected with the negative terminal U-of bus, the square-wave signal of a Signal Generator of Ultra-low Frequency output 1Hz, be transformed into the sinusoidal signal of 1Hz through digital to analog converter, be about to digital signal and convert simulating signal to, after the sinusoidal signal of this 1Hz is amplified through a power amplifier, presenting isolator by No. one is fed on the bus, presenting isolator for No. one is made of choking coil L1 and coupling capacitance C1 series connection, ultra-low frequency signal is fed on the dc bus by large electric capacity, can guarantees that signal source is not subjected to the impact of bus high direct voltage.But when having over the ground larger interchange to disturb on the bus, tend to make the signal source cisco unity malfunction even make the signal source generating circuit impaired, so signal source not only wants the isolated DC source, also will isolate alternating current source.Ultra-low frequency signal is fed on the dc bus with the buffer circuit that large electric capacity forms by the current limliting circle by an amount of inductance, so both can have made signal source not be subjected to the impact of bus high pressure, also suppressed to exchange the impact of disturbing it.
Owing to have DC current to flow through on the bus, so being fed to bus, the sinusoidal signal of 1Hz goes forward, be with voltage, electric current, the amplitude raising with the sinusoidal signal of 1Hz of power amplifier, reduce disturbance,
The branch road detection module has a plurality of, in the present embodiment, the branch road detection module has 16, each branch road detection module is comprised of analog selection switch, signal amplifier, prime wave filter, phase comparator, rear class wave filter, analog to digital converter, a coprocessor, the input end of analog selection switch is connected with mutual inductor, and mutual inductor is enclosed within on the branch road loop.
In the present embodiment, each branch road detection module is responsible for detecting 16 branch road loops, that is to say, first branch road detection module is responsible for detecting 16 branch road loops, second branch road detection module is responsible for detecting 16 branch roads, the rest may be inferred, the branch road loop that first branch road detection module is responsible for detecting has 16, the mutual inductor corresponding with it has 16, respectively mutual inductor H1 to H16, each mutual inductor is enclosed within respectively on the branch road loop, the input end of analog selection switch is connected with 16 mutual inductors respectively, the branch road loop that second branch road detection module is responsible for detecting has 16, the mutual inductor corresponding with it has 16, is respectively mutual inductor H17 to H32, and each mutual inductor is enclosed within respectively on the branch road loop, the input end of analog selection switch is connected with 16 mutual inductors respectively, now describes as an example of first branch road detection module example.The output terminal of analog selection switch is connected with the input end of signal amplifier, signal amplifier is made of integrated operational amplifier, its effect be with transformer induced to faint AC signal (sinusoidal signal) amplify, the output terminal of signal amplifier is connected with the input end of prime wave filter, the output terminal of prime wave filter is connected with the input end of phase comparator, the output terminal of phase comparator is connected with the input end of rear class wave filter, the output terminal of rear class wave filter is connected with the input end of an analog to digital converter, No. one the analog to digital converter output terminal is connected with the I/O port of coprocessor, the model of an analog to digital converter is TLC1543, the communication port of coprocessor is connected with the communication port of primary processor by level transferring chip (model is MAX485), thereby realize communicating by letter between coprocessor and the primary processor, the model of coprocessor is W78E51, the communication port of primary processor also is connected with the communication port of a Signal Generator of Ultra-low Frequency, for Signal Generator of Ultra-low Frequency provides the steering order signal, the synchronous signal output end mouth of a Signal Generator of Ultra-low Frequency is connected with phase comparator in the branch road detection module, after Signal Generator of Ultra-low Frequency is received the steering order signal that primary processor sends, just produce periodically digital sine value, be transformed to the 1Hz analog sinus signals through a digital to analog converter again, after a power amplifier amplifies, inject over the ground DC bus system by the isolator of presenting that is comprised of coupling capacitance C1 and choking coil L1, mutual inductor is installed on each branch road loop of bus.
If branch road has resistance eutral grounding on the loop, the mutual inductor that then is contained on this branch road produces induction current, and the resistance of faradic size and grounding resistance is inversely proportional to.The analog selection switch is controlled by coprocessor CPU, the induced signal that mutual inductor produces on the acquisition time different branch loop, signal amplifier amplifies the sensor current signal that gathers, through prime wave filter elimination noise jamming, sensor current signal is become the sinusoidal signal that centre frequency is 1Hz, and this signal becomes DC voltage through phase comparator, rear class wave filter, and DC voltage is after analog to digital conversion, send coprocessor to carry out data and process, send into main frame by the RS485 interface again.Main frame is controlled on the one hand the branch road detection module and is gathered the transformer induced signal of each branch road orderlyly, and the data sent here of receiving branch detection module are again finished branch road and patrolled and examined on the other hand.
Phase comparator in the branch road detection module, its effect are to eliminate ground capacitance (being produced by capacitive load) on the branch road loop to the impact of measurement of Grounding Resistance degree of accuracy, also can overcome on the bus asynchronous AC signal simultaneously and disturb.The data that primary processor in the main frame receives after treatment, on the one hand the liquor charging crystal display shows and output alarm, on the other hand data communication device is crossed communication interface circuit (RS232 or RS485) and is sent to host computer.
Please refer to Fig. 3, setting also is provided with the mother detection module in the main frame, the mother detection module is by No. two Signal Generator of Ultra-low Frequency, No. two digital to analog converters, No. two power amplifiers, sample circuits and present isolator No. two and form, No. two Signal Generator of Ultra-low Frequency are that the single-chip microcomputer of AT89C2051 consists of by model, and No. two digital to analog converters are that the analog-digital chip of DAC0832 consists of by model.No. two power amplifier is made of power tube, presenting isolator choking coil L2 and coupling capacitance C2 series connection for No. two consists of, the square-wave signal output port of No. two Signal Generator of Ultra-low Frequency is connected with the input end of No. two digital to analog converters, the output terminal of No. two digital to analog converters is connected with the input end of No. two power amplifiers, the output terminal of No. two power amplifiers is connected with the input end of presenting isolator for No. two, the output terminal of presenting isolator for No. two is connected with the negative terminal of bus, the square-wave signal of No. two Signal Generator of Ultra-low Frequency output 1Hz, be transformed into the sinusoidal signal of 1Hz through digital to analog converter, be about to digital signal and convert simulating signal to, after the sinusoidal signal of this 1Hz is amplified through No. two power amplifiers, presenting isolator by No. two is fed on the bus, owing to have DC current to flow through on the bus, so the sinusoidal signal of 1Hz is fed to bus goes forward, will be with No. two power amplifiers voltage with the sinusoidal signal of 1Hz, electric current, amplitude improves, reduce disturbance, the square-wave signal output port of No. two Signal Generator of Ultra-low Frequency is connected with the input end of No. two digital to analog converters, the output terminal of No. two digital to analog converters is connected with the input end of No. two power amplifiers, the output terminal of No. two power amplifiers be connected with the input end of presenting isolator for No. two through over-sampling circuit, the output terminal of presenting isolator for No. two is connected with the negative terminal U-of bus, the output terminal of sample circuit is connected with the input end of No. two analog to digital converters, the output terminal of No. two analog to digital converters is connected with the sampled voltage input port of No. two Signal Generator of Ultra-low Frequency, the communication port of No. two Signal Generator of Ultra-low Frequency is connected with the communication port of primary processor, send the mother detection signal to primary processor, receive simultaneously the steering order signal that primary processor is sent, the ultimate principle of mother monitoring is that No. two Signal Generator of Ultra-low Frequency produce the 1Hz sinusoidal signal, presented the ultra-low frequency signal of 1Hz to the negative terminal of second segment bus by the negative terminal of first paragraph bus, if there is not mother, do not consist of signal circuit, do not have loop current; Perhaps, because first paragraph bus and second segment bus have resistance and capacity earth, can consist of signal circuit, but the loop current size is limited.If mother is arranged, then consist of signal circuit, loop current is larger, like this, can according to the size of loop current, judge accurately whether first, second section bus has mother to exist.
Please refer to Fig. 4, setting also is provided with the bus insulation detection module in the main frame, the bus insulation detection module is by balanced bridge, unbalanced bridge, No. three analog to digital converters, No. four analog to digital converters and change-over switch consist of, the input end of balanced bridge is connected with negative terminal U-with the anode U+ of bus, the output terminal of balanced bridge is connected with the input end of No. three analog to digital converters, the output terminal of No. three analog to digital converters is connected with the sampled voltage input port of primary processor, the model of No. three analog to digital converters is TC14433, balanced bridge is by two potentiometer W1, W2 consists of, two potentiometer W1, the resistance of W2 equates, resistance can be 180K, potentiometer W1 is connected with the anode U+ of bus, potentiometer W2 is connected with the negative terminal U-of bus, when bus just, negative terminal U+, when U-does not have ground connection, when keeping good insulation namely and between the ground, potentiometer W1, the voltage of W2 output equates, at this moment by the sequential operation of main frame inside, can detect bus anode voltage-to-ground and bus negative terminal voltage-to-ground.
When dc bus anode U+ or negative terminal U-insulation decline, the voltage of potentiometer W1, W2 output is no longer equal, primary processor is through behind the sequential operation, just can judge the resistance of dc bus anode or negativing ending grounding, when resistance during less than the threshold values set, primary processor sends alerting signal, starts alarm equipment alarm.Change-over switch is by No. one, No. two relay consists of, the end of the coil K1 of a relay is connected with power supply+12V, the other end of the coil K1 of a relay is connected with a driving circuit, No. one driving circuit is made of triode and Darlington transistor, the base stage of triode is connected with the first trigger pip output port of primary processor, two trigger pip output ports of primary processor all are made of general purpose I/O port, the trigger pip of the first trigger pip output port output is by height, low level consists of, during high level, the triode conducting, Darlington transistor work, carrying out electric current amplifies, make the coil K1 of a relay get electric, during low level, the triode cut-off, Darlington transistor quits work, the coil K1 dead electricity of a relay, the contact K1A of a relay is normally opened contact, the end of the coil K2 of No. two relays is connected with power supply+12V, the other end of the coil K2 of No. two relays is connected with No. two driving circuits, No. two driving circuit is made of triode and Darlington transistor, the base stage of triode is connected with the second trigger pip output port of primary processor, the trigger pip of the second trigger pip output port output of primary processor is by height, low level consists of, during high level, the triode conducting, Darlington transistor work, carrying out electric current amplifies, make the coil K2 of No. two relays get electric, during low level, the triode cut-off, Darlington transistor quits work, the coil K2 dead electricity of No. two relays, the contact K2A of No. two relays is normally opened contact, unbalanced bridge is made of two bridge circuits, first bridge circuit is by resistance R 1, R2, potentiometer W3 consists of, resistance R 1, after the R2 series connection, just be connected across bus by normally opened contact K1A, negative terminal U+, on the U-end, the resistance of resistance R 1 is 80K, the resistance of resistance R 2 is 120K, potentiometer W3 is connected to resistance R 1, on the contact between the R2, with resistance R 1, R2 forms T shape and connects, the sliding end of potentiometer W3 is connected with the input end of No. four analog to digital converters, and the output terminal of No. four analog to digital converters is connected with the sampled voltage input port of primary processor.The model of No. four analog to digital converters is TC14433, second bridge circuit is made of resistance R 3, R4, potentiometer W4, after resistance R 3, the R4 series connection, be connected across by normally opened contact K2 on the positive and negative end U+, U-end of bus, the resistance of resistance R 3 is 120K, the resistance of resistance R 4 is 80K, potentiometer W4 is connected on the contact between resistance R 3, the R4, forming T shape with resistance R 3, R4 is connected, the sliding end of potentiometer W4 is connected with the input end of No. four analog to digital converters, and the output terminal of No. four analog to digital converters is connected with the sampled voltage input port of primary processor.When the coil K1 of a relay gets when electric, normally opened contact K1A is closed, when the coil K1 of relay dead electricity, normally opened contact K1A opens, and when the coil K2 of No. two relays gets when electric, normally opened contact K2A is closed, when the coil K2 of No. two relays dead electricity, normally opened contact K2A opens, thereby two bridge circuits of unbalanced bridge are alternately accessed and is connected and being connected of bus, the frequency that replaces can be 45 seconds once.The reason that designs two place's bridge circuits is: dc bus insulation resistance over the ground is divided into bus anode insulation against ground resistance (R+) and bus negative terminal insulation against ground resistance (R-).Press the circuit first principles analysis, ask for two unknown numbers of R+ and R-, must set up two groups of independently electric loop equations, again with its simultaneous solution, can try to achieve the resistance value of R+ and R-.
As the positive and negative end U+ of bus, when U-does not have ground connection, when keeping good insulation namely and between the ground, positive and negative being in equal proportions of voltage of potentiometer W3, W4 output, when dc bus anode U+ or negative terminal U-insulation decline, the positive and negative ratio of voltage of potentiometer W3, W4 output is no longer equal, and primary processor is through behind the sequential operation, just can judge the resistance of dc bus anode U+ or negative terminal U-ground connection, when resistance during greater than the threshold values set, primary processor sends alerting signal, starts alarm equipment alarm.
This instrument is monitored bus by balanced bridge and unbalanced bridge, the advantage of balanced bridge is that Measuring Time is short, bus just, the negative terminal voltage-to-ground does not swing, but can only measure bus anode insulation against ground resistance or bus negative terminal insulation against ground resistance, unbalanced bridge can just measured bus simultaneously, negative terminal insulation against ground resistance, but Measuring Time is long, and bus just, the negative terminal voltage-to-ground has swing, in order to take into account two kinds of circuit and advantage, allow the work of two kinds of circuit automatic alternates, most of the time is operated in the balancing circuitry state, and seldom time service is at the unbalanced circuit state.When insulation is lower than 40K, then be operated in the unbalanced circuit state.
Balance bridge can only be measured the single-ended insulation against ground resistance of bus; Two uneven bridges can be measured bus both-end insulation against ground resistance, but Measuring Time is longer, and bus two ends voltage-to-ground has swing.In order to take into account the advantage of above-mentioned two kinds of measuring methods, we adopt and allow the measuring method of two kinds of circuit automatic alternates work: relay K 1 during at ordinary times instrument work, and the normally opened contact of K2 all disconnects, and circuit working is at the balanced bridge state; When insulation is lower than 40K, relay K 1, the normally opened contact of K2 is connected in turn, and then circuit working is at the unbalanced bridge state.
Please refer to Fig. 4, this instrument can also be monitored bus and be exchanged over the ground interference voltage, be provided with in the main frame and exchange the interference voltage detection module, exchange the interference voltage detection module by coupled circuit, rectification circuit, filtering circuit, No. five analog to digital converter forms, the input end of coupled circuit is connected with bus, the output terminal of coupled circuit is connected with the input end of rectification circuit, the output terminal of rectification circuit is connected with the input end of filtering circuit, the output terminal of filtering circuit is connected with the input end of No. five analog to digital converters, and the output terminal of No. five analog to digital converters is connected with the sampled voltage input port of primary processor.Coupled circuit is comprised of capacitor C 3 and current limliting circle L3, in transformer station and generating plant, sometimes with dc feeder with exchange feeder line and walk together, often because insulation decline between the AC and DC feeder line, cause that straight-flow system is subject to alternating voltage and disturbs, affect the equipment component normal operation, even damage equipment, exchange to disturb in order getting rid of, must to monitor and patrol exchanging interference voltage.
This instrument internal is provided with and exchanges the interference voltage detection module, the monitoring that exchanges interference voltage is will exchange interference voltage by electric capacity and current limit by inductance circle to introduce detector with the principle of work of inspection, give primary processor through rectification, filtering, A/D conversion, if it is larger to exchange interference voltage, and internal resistance is very little again, and primary processor sends instruction, and instrument enters branch road and patrols and examines state, patrol and examine to find exchange to disturb by branch road and scurry into branch road, and measure its internal resistance value.
The detection principle of branch road loop insulation resistance is: transformer station and generating plant are to the DC load of particular importance, sometimes supply with simultaneously with two branch road loops, so just consisted of the branch road loop, if there is branch road loop insulation to descend in the loop, at this moment loop can produce shunting, the marking current that flows through branch road reduces relatively, the electric current that mutual inductor on this branch road is responded to also reduces relatively, the grounding resistance value of namely measuring is bigger than normal, in order to increase the electric current in the mutual inductor, mutual inductor on the loop can be in series, as shown in Figure 5, mutual inductor H1, H2 is in series, mutual inductor H3, H4 is in series, then induction current increases, and the measured value of grounding resistance conforms to actual, thereby has overcome the measured deviation that the shunting action because of loop causes.
The branch road loop refers to that two branch road loops are common for a load, if Grounding appears in load, the low frequency signal that is fed on the bus can be divided into two paths of signals, can affect measuring accuracy.The branch road loop detection technique is difficult problem in the detection technique, solves in the past never, and we take two mutual inductors are in series on the loop method to overcome the measured deviation that the shunting action because of loop causes.Thereby well solved the detection difficult problem of branch road loop.
Main frame is installed in the direct-current cabinet, and it is indoor that the branch road detection module can be installed in direct current cabinet, also can be installed in the control power supply room or in the relay bungalow.This instrument workflow is divided into the two large divisions: insulating monitoring and branch road are patrolled and examined.Insulating monitoring is that instrument is to the long term monitoring of the variation of straight-flow system busbar voltage and bus insulation decline.When insulation resistance was arranged less than the insulated door limit value, instrument sent insulation alarm; When insulation resistance during less than the stake resistance thresholding, instrument changes automatic inspection state over to, searches the ground connection branch road occurs.
Claims (6)
1. D. C. system earthing detector, consisted of by main frame and a plurality of branch road detection module, the structure of each branch road detection module is identical, it is characterized in that: be provided with primary processor and ultra-low frequency signal source in the described main frame, primary processor is made of single-chip microcomputer, the ultra-low frequency signal source is by a Signal Generator of Ultra-low Frequency, a digital to analog converter, a power amplifier, presenting isolator for No. one forms, the square-wave signal output port of a Signal Generator of Ultra-low Frequency is connected with the input end of a digital to analog converter, the output terminal of a digital to analog converter is connected with the input end of a power amplifier, the output terminal of a power amplifier is connected with the input end of presenting isolator for No. one, the output terminal of presenting isolator for No. one is connected with the negative terminal of bus, described branch road detection module is by the analog selection switch, signal amplifier, the prime wave filter, phase comparator, the rear class wave filter, an analog to digital converter, coprocessor forms, the input end of analog selection switch is connected with mutual inductor, mutual inductor is enclosed within on the branch road loop, the output terminal of analog selection switch is connected with the input end of signal amplifier, the output terminal of signal amplifier is connected with the input end of prime wave filter, the output terminal of prime wave filter is connected with the input end of phase comparator, the output terminal of phase comparator is connected with the input end of rear class wave filter, the output terminal of rear class wave filter is connected with the input end of an analog to digital converter, No. one the analog to digital converter output terminal is connected with the I/O port of coprocessor, the communication port of coprocessor is connected with the communication port of primary processor by level transferring chip, thereby realize communicating by letter between coprocessor and the primary processor, the communication port of primary processor also is connected with the communication port of a Signal Generator of Ultra-low Frequency, for Signal Generator of Ultra-low Frequency provides the steering order signal, the synchronous signal output end mouth of Signal Generator of Ultra-low Frequency is connected with phase comparator in the branch road detection module.
2. a kind of D. C. system earthing detector as claimed in claim 1, it is characterized in that: also be provided with the mother detection module in the described main frame, the mother detection module is by No. two Signal Generator of Ultra-low Frequency, No. two digital to analog converters, No. two power amplifiers, sample circuit and present isolator for No. two and form, the square-wave signal output port of No. two Signal Generator of Ultra-low Frequency is connected with the input end of No. two digital to analog converters, the output terminal of No. two digital to analog converters is connected with the input end of No. two power amplifiers, the output terminal of No. two power amplifiers be connected with the input end of presenting isolator for No. two through over-sampling circuit, the output terminal of presenting isolator for No. two is connected with the negative terminal of bus, the output terminal of sample circuit is connected with the input end of No. two analog to digital converters, the output terminal of No. two analog to digital converters is connected with the sampled voltage input port of No. two Signal Generator of Ultra-low Frequency, the communication port of No. two Signal Generator of Ultra-low Frequency is connected with the communication port of primary processor, send the mother detection signal to primary processor, receive simultaneously the steering order signal that primary processor is sent.
3. a kind of D. C. system earthing detector as claimed in claim 1, it is characterized in that: also be provided with the bus insulation detection module in the described main frame, the bus insulation detection module is by balanced bridge, unbalanced bridge, No. three analog to digital converters, No. four analog to digital converters and change-over switch consist of, the input end of balanced bridge is connected with negative terminal with the anode of bus, the output terminal of balanced bridge is connected with the input end of No. three analog to digital converters, the output terminal of No. three analog to digital converters is connected with the sampled voltage input port of primary processor, the input end of unbalanced bridge is connected with negative terminal with the anode of bus through change-over switch, the output terminal of unbalanced bridge is connected with the input end of No. four analog to digital converters, and the output terminal of No. four analog to digital converters is connected with the sampled voltage input port of primary processor.
4. a kind of D. C. system earthing detector as claimed in claim 3, it is characterized in that: described change-over switch is made of relay.
5. a kind of D. C. system earthing detector as claimed in claim 1 is characterized in that: describedly present isolator No. one and be made of choking coil and coupling capacitance series connection.
6. a kind of D. C. system earthing detector as claimed in claim 1, it is characterized in that: also be provided with in the described main frame and exchange the interference voltage detection module, exchange the interference voltage detection module by coupled circuit, rectification circuit, filtering circuit, No. five analog to digital converter forms, the input end of coupled circuit is connected with bus, the output terminal of coupled circuit is connected with the input end of rectification circuit, the output terminal of rectification circuit is connected with the input end of filtering circuit, the output terminal of filtering circuit is connected with the input end of No. five analog to digital converters, and the output terminal of No. five analog to digital converters is connected with the sampled voltage input port of primary processor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201220600166 CN202886514U (en) | 2012-11-13 | 2012-11-13 | Direct current (DC) system grounding detector |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201220600166 CN202886514U (en) | 2012-11-13 | 2012-11-13 | Direct current (DC) system grounding detector |
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