CN104655908A - Signal transmission device and method for current transformer - Google Patents
Signal transmission device and method for current transformer Download PDFInfo
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- CN104655908A CN104655908A CN201510102017.2A CN201510102017A CN104655908A CN 104655908 A CN104655908 A CN 104655908A CN 201510102017 A CN201510102017 A CN 201510102017A CN 104655908 A CN104655908 A CN 104655908A
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Abstract
The invention provides a signal transmission device and method for a current transformer, and belongs to the field of electrical measurement. The device comprises a primary side (1) and a secondary side (6) which are connected with an optical fiber (4). The device is characterized in that the primary side (1) comprises a coil, a signal conditioning unit and a constant-current drive unit end which are sequentially connected; the secondary side (6) comprises a photoelectric detection unit and a signal extraction unit. The method comprises steps as follows: (1), obtaining multiple groups of (U,P) values; (2), obtaining a power-drive voltage curve of a luminescent tube; (3), storing a parameter of the primary side (1) on the secondary side (6); (4), obtaining a reference value of direct-current voltage and an effective value of a power frequency signal on the secondary side; (5), obtaining an effective value of a power frequency voltage signal on the primary side (1); (6), obtaining an effective value of bus current on the primary side (1). The signal transmission device and method can be used for accurately calculating the effective values of the power frequency voltage signal and the bus current on the primary side and can be applied to the design of the high-precision current transformer.
Description
Technical field
For signal transmitting apparatus and the method for current transformer, belong to electric measurement field.
Background technology
In electrical production, electrical power transmission system and power equipment, current transformer is the visual plant realizing electric energy measurement and system protection.Traditional electromagnetic current transducer owing to having insulation difficulty, be subject to electromagnetic interference (EMI), volume is large, high in cost of production self is difficult to the shortcoming that overcomes and gradually replace by novel current transformer.In various novel current transformer, advantages such as electronic mutual inductor relies on its good insulation preformance, antijamming capability is strong, size is little, cost is low, measurement dynamic range is wide, highly sensitive, security of operation and become the ideal substitute of conventional electromagnetic current transformer gradually.
Electronic mutual inductor is based on electronic technology and fibre-optic transmission system (FOTS), its ultimate principle is the analog current signal adopting primary current sensor (as air core coil or iron-core coil) bus current to be transformed to fractional value according to the turn ratio of coil, again this current signal is converted to analog voltage signal, after this by AD sampling, analog voltage signal is converted to digital signal, digital optical signal is converted to sending into luminotron driving circuit after encoding digital signals by electrical/optical by CPU, utilize optical fiber by optical signal transmission to secondary side circuit, complete light/electricity conversion successively, obtain the digital output of bus current size after decoding or after decoding, exported the signal of reflection bus current waveform by D/A conversion.
The electronic current mutual inductor of above principle design is used to have following shortcoming:
(1) because its primary side exists AD conversion link, cause primary side circuit power consumption higher, and the powerup issue of current transformer primary side is also one of difficult problem of estimated current mutual inductor design.
(2) what whole system adopted the transmission of signal is digital signal, therefore sample frequency during AD sampling just limits the bandwidth of the signal that will transmit, according to higher sample frequency, then system power dissipation is larger, therefore the sample frequency of real system usually can not be too large, and when making the high-frequency harmonic in electric current or fault, more the travelling wave signal of high frequency cannot transfer to secondary side by the restriction of sample frequency.And these high-frequency signals are exactly the important informations that power quality analysis or line fault are analyzed, so make the limited efficacy of current transformer.
(3) in real system, because three-phase bus all will have current transformer, therefore will represent that the digital quantity of bus current size must carry out synchronous coding to the signal on each road before sending into electrical/optical change-over circuit, the three road signals received to enable secondary side are synchronous, therefore add the complexity of system to a certain extent.
The luminotron adopted in electric mutual inductor generally by current drive-type device as LED or laser diode LD realize, the size of its luminous power depends on the electric current flowing through luminotron, when the electric current flowing through luminotron increases to a certain degree, the luminous power of luminotron
with flow through its electric current
linear.The electric current that photoelectric tube exports when there being illumination
with the intensity of illumination be subject to
also be linear relationship.
Utilize the above characteristic of luminotron and photoelectric tube, have analog voltage signal (i.e. power frequency component) the directly modulation luminotron before primary side being entered luminotron driving circuit in the prior art luminous, directly become analog optical signal by this analog voltage signal and send into light/power conversion circuit that optical fiber passes to secondary side, then can avoid the AD sampling element of primary side circuit, thus also just solve the problem that primary side circuit power consumption is too high and signal transmission frequency band is limited; Meanwhile, due to directly by simulating signal modulation transmissions, also without the need to carrying out synchronously to the three-phase data of real system, then the complexity of system can be made greatly to reduce.So also just solve the problems referred to above existing for current electronic current mutual inductor.
In actual applications, when primary side uses simulating signal to modulate light signal, the DC offset voltage signal of a fixed size will be provided usually, this signal is also as reference signal, by this signal, modulated-analog signal is raised to the linear zone of luminotron, thus realizing the transmission of analog optical signal, this is the ultimate principle utilizing luminotron to realize analog signal transmission.But, light signal can because of the coupling loss between luminotron and the joints of optical fibre in transmitting procedure, fiber transmission attenuation, coupling loss between the joints of optical fibre and photoelectric tube, degradation reason under the aging luminous power caused of luminotron thus cause signal magnitude occur decay, to calculate the size of primary side power frequency current signal by measuring secondary side power frequency component size, the decay of power frequency component must be known, simply the decay of DC reference signal can be used as the decay of power frequency component, but it is unequal due to the decay of two signals, the error of the current transformer therefore designed in this way is larger, the method is feasible for the current transformer of design protection, but it is then impracticable for the method being used for designing high-precision Verification of Measuring Current Transformer.
Summary of the invention
The technical problem to be solved in the present invention is: overcome the deficiencies in the prior art, a kind of simple and convenient, with low cost, energy accurate Calculation primary side power frequency current signal size is provided, may be used on the signal transmitting apparatus for current transformer in the design of high-precision current transformer and method.
The technical solution adopted for the present invention to solve the technical problems is: this is used for the signal transmitting apparatus of current transformer, comprise by the primary side of Fiber connection and secondary side, it is characterized in that: in described primary side, the input end of the output terminal connection signal conditioning unit of the coil of connection bus, the output terminal of signal condition unit connects the input end of constant current driving unit, and the output terminal of constant current driving unit connects one end of described optical fiber;
The input end of photoelectric detection unit in the other end connecting secondary side of optical fiber, the input end of the output terminal connection signal extraction unit of photoelectric detection unit, is carried out the output of signal by the output terminal of signal extraction unit.
Preferably, described signal extraction unit at least comprises capacitance and CPU (central processing unit), and the signal of described photoelectric detection unit is divided into two-way: capacitance of leading up to is connected with CPU (central processing unit), and another road is directly connected with CPU (central processing unit).
Preferably, described photoelectric detection unit at least comprises: photoelectric tube light signal being converted to current signal and the current signal be converted to by photoelectric tube are converted to the current-voltage conversion circuit of voltage signal.
Preferably, described signal condition unit at least comprises: the voltage reference chip that can generate DC reference voltage, and the power frequency component exported by described coil and reference voltage carry out the signal mixed circuit that mixes.
Preferably, described constant current driving unit at least comprises the transfer resistance that the voltage signal that signal condition unit exports is converted to current signal and the current signal be converted to by transfer resistance carries out driving luminous luminotron.
Preferably, described luminotron is communication luminotron.
Preferably, described transfer resistance is the thermistor of negative temperature coefficient.
For the method for transmitting signals of the signal transmitting apparatus of current transformer, it is characterized in that: comprise the steps:
Step 1, exports the different DC voltage of many group numerical value to constant current driving unit, drives luminotron with different power light-emittings, obtain many groups U-P numerical value of luminotron;
Step 2, the many groups obtained by step 1 U-P numerical fitting obtains the P-U relation curve of the luminous power-driving voltage of luminotron:
, and by coefficient a, b, calculate the temperature coefficient of thermistor in constant current driving unit according to heat-sensitive coefficients method of testing;
Step 3, by coefficient a, the b in P-U relation curve in step 2 and the DC reference voltage signal by the voltage reference chip generation in signal conditioning circuit
value be stored in the CPU (central processing unit) of signal extraction unit in secondary side;
Step 4, CPU (central processing unit) circuit samples respectively to the signal that photoelectric detection unit exports, and calculates the DC reference signal value decayed after Optical Fiber Transmission
value and the effective value of power frequency component
;
Step 5, according to the power frequency component that power frequency component computing formula calculates first siding ring output or obtained by signal condition cell translation
;
Step 6, according to the power frequency component that step 5 calculates
calculate the effective value of bus.
Preferably, the power frequency component computing formula described in step 5 is:
Wherein, a, b are respectively the P-U relation curve of luminotron
coefficient,
the DC reference voltage produced for using voltage reference chip in signal condition unit,
,
be respectively CPU (central processing unit) to sample the reference voltage after the decay that obtains
and power frequency component.
Preferably, the heat-sensitive coefficients method of testing described in step 2, comprises the steps:
Step a, under normal temperature T1, exports a constant driving DC voltage to constant-current drive circuit;
Step b, utilizes potentiometer to replace thermistor and measures the initial resistivity value R1 of potentiometer;
Step c, the luminous power P1 of record luminotron under temperature T1;
Steps d, uses heating device that the working temperature of luminotron is increased to T2, and the luminous power P2 of luminotron under being recorded in temperature T2;
Step e, the working temperature keeping luminotron is T2, and constantly reduces the resistance of potentiometer, and now the luminous power of luminotron 2 starts to raise, when the luminous power of luminotron rises to P1, record potentiometer resistance R2 now;
Step f, by calculating the difference of the working temperature of luminotron
=T2-T1, and the drop-out value of potentiometer resistance
=R1-R2, calculates the temperature coefficient that thermistor should have, and completes the selection to thermistor according to this principle.
Compared with prior art, the beneficial effect that the present invention has is:
1, the present invention is when calculating power frequency component effective value, attenuation degree not exclusively by reference to signal calculates, and therefore can accurately calculate primary side power frequency component effective value, may be used in the design of high-precision current transformer, have simple and convenient, advantage with low cost simultaneously.
2, in signal extraction unit, by arranging capacitance and CPU (central processing unit), isolation and the accurate Calculation of deamplification can be realized.
3, in signal condition unit, the voltage reference chip of exportable reference voltage is set, luminotron can be made to be in linear output range on the one hand, can be used as the reference that power frequency component calculates on the other hand.
4, the transfer resistance in constant current driving unit is the thermistor of negative temperature coefficient, and compensate for temperature and raise the luminotron luminous power decline caused, coefficient a, b in its P-U relation can remain unchanged.
5, be used for, in the signal transmitting apparatus of current transformer, the power frequency simulating signal of primary side directly to be transferred to secondary side at this, without the need to arranging sampling element in once surveying, primary side circuit power consumption is lower, and circuit design is simple.
Accompanying drawing explanation
Fig. 1 is the signal transmitting apparatus functional-block diagram for current transformer.
Fig. 2 is the signal transmitting apparatus signal extraction unit functional-block diagram for current transformer.
Fig. 3 is the method for transmitting signals process flow diagram for current transformer.
Fig. 4 is luminotron drive current I-luminescence efficiency P curve map.
Fig. 5 is luminotron input voltage U-luminous power P curve map.
Fig. 6 is input voltage U-luminous power P curve map under different temperatures.
Fig. 7 is the heat-sensitive coefficients test flow chart of thermistor.
Wherein: 1, primary side 2, luminotron 3, the joints of optical fibre 4, optical fiber 5, photoelectric tube 6, secondary side.
Embodiment
Fig. 1 ~ 7 are most preferred embodiments of the present invention, and below in conjunction with accompanying drawing 1 ~ 7, the present invention will be further described.
As shown in Figure 1, for the signal transmitting apparatus of current transformer, comprise the primary side 1 and secondary side 6 that are connected by optical fiber 4.Primary side 1 comprises coil, signal condition unit, constant current driving unit.The input end of coil is connected with bus, the input end of its output terminal connection signal conditioning unit, the output terminal of signal condition unit connects the input end of constant current driving unit, the output terminal of constant current driving unit passes through one end of the joints of optical fibre 3 connecting fiber 4 in primary side 1, and secondary side 6 is by the other end of the joints of optical fibre 3 connecting fiber 4 in it.Secondary side 6 comprises photoelectric detection unit and signal extraction unit.Input end connecting secondary side 6 joints of optical fibre 3 of photoelectric detection unit, the input end of its output terminal connection signal extraction unit.
Coil is generally air core coil or iron-core coil.In actual product, bus current is become analog voltage signal by built-in integrating circuit and directly exports by air core coil usually; Bus current is converted to analog voltage signal and directly exports by an iron-core coil usually built-in shunt resistance; Also the iron-core coil of traditional direct output analog current signal can be adopted to realize, now will corresponding transfer resistance be set in signal condition unit and current signal is become analog voltage signal.Any one adopting above-mentioned three types when coil is when realizing, and its analog voltage signal directly or indirectly exported is designated as
.Be provided with in signal condition unit and export DC reference voltage signal
voltage reference chip, and by signal condition unit by the signal mixed circuit in it by d. c. voltage signal
with analog voltage signal
carry out mixing rear output, as the input voltage signal of constant current driving unit
, namely
, signal mixed circuit can utilize prior art, is realized the mixing of two signals by integrated operational amplifier.Blended voltage signals
after being admitted to constant current driving unit, being converted to current signal by constant current driving unit and driving the luminotron 2 in it luminous.The light that luminotron 2 sends enters optical fiber 4 through the joints of optical fibre 3 and delivers in the joints of optical fibre 3 of secondary side 6.
After the light signal that primary side 1 sends is admitted to secondary side 6, first enter in photoelectric detection unit, light signal is converted to current signal by the photoelectric tube 5 in photoelectric detection unit, then current conversion is voltage signal by the current-voltage conversion circuit in photoelectric detection unit
export.Current-voltage conversion circuit at least comprises feedback resistance and the integrated operational amplifier that current signal is converted to voltage signal by.By the voltage signal that current-voltage conversion circuit obtains
to compare voltage signal
can decline because of the coupling loss between luminotron 2 and the joints of optical fibre 3, fiber transmission attenuation, the coupling loss between the joints of optical fibre 3 and photoelectric tube 5, the aging luminous power caused of luminotron 2 and cause decaying, therefore
,
with
be respectively the reference voltage signal after decay
and analog voltage signal
.Voltage signal
be admitted in signal extraction unit, signal extraction unit comprises CPU (central processing unit) and capacitance as shown in Figure 2, the voltage signal that photoelectric detection unit exports
be divided into two-way, CPU (central processing unit) is sent into through capacitance in a road, and CPU (central processing unit) is directly sent in another road.D. c. voltage signal is removed through capacitance
rear reservation analog voltage signal
, the signal that CPU (central processing unit) is sent into according to two-way is right respectively
with
carry out sampling and calculating, reduction obtains original analog voltage signal
.
As shown in Figure 3, for the method for transmitting signals of current transformer, comprise the steps:
Step 1, obtains (U, P) numerical value under many group normal temperature.
Before equipment dispatches from the factory, at room temperature, the different d. c. voltage signal Uc of many group numerical value is exported to constant current driving unit by signal generator, drive luminotron 2 luminous by different DC voltage Uc constant current driving unit, and obtain organizing performance number accordingly by light power meter, obtain many groups of (U, P) numerical value of luminotron 2. more
Luminotron 2(is as LED) be current mode device, its driving circuit uses constant current to drive, i.e. its luminous power
determined by the electric current I flowing through it.The complete P-I relation curve of luminotron 2 as shown in Figure 4, due to the existence of luminotron 2 dead zone voltage when luminescence, makes this curved line relation be not complete linear relationship close to the relation of second order polynomial.But along with flowing through the continuous increase of LED current, its P-I relation then presents good linear relationship gradually.As shown in Figure 4, electric current I is from I
1its P-I relation is linear relationship afterwards.
When implementing the method for transmitting signals of this current transformer, the scope controlling working current by hardware circuit (as controlled the size of thermistor in the size of DC offset voltage or constant-current drive circuit) exists
with
between, then the P-I relation of this section is also linear naturally.In real system, LED drive circuit due to the present invention's application is that constant current drives, the input voltage U of the electric current I and this constant current driving unit that therefore flow through LED is the multiple proportion of a resistance R, therefore, when applying, only needing to measure the P-U relation of this LED constant current driving unit used and not needing to measure P-I relation.Its reason is that the actual output of signal condition unit before constant current driving unit is exactly an analog voltage signal but not current signal.
Step 2, obtains luminotron power-driving voltage curve.
Many groups of (U, P) numerical fittings obtained by step 1 obtain the P-U relation curve of luminotron power-driving voltage, and P-U relation curve meets formula:
.In reality is implemented, the magnitude of voltage exported due to signal condition unit output terminal is d. c. voltage signal
with analog voltage signal
carry out mixing rear magnitude of voltage
, therefore magnitude of voltage after mixing
meet above-mentioned formula equally, obtain formula (1):
formula (1)
As shown in Figure 5, communication LED(such as the wavelength for a specific model is the red visible LED of 650nm), at (U1, U2) section that the P-U relation linearity is good, its P-U relation coincidence formula (1):
, wherein
.Corresponding a, b value can by utilizing signal generator to apply several (U to the constant current driving unit of this LED
1, U
2) interval d. c. voltage signal, measure the luminous power value that each voltage signal is corresponding accordingly, utilize software (as Matlab) to carry out curve fitting to these points and can obtain the value of a, b.Light power meter is used to realize to the measurement of the luminous power of luminotron 2.
When the present invention is applied to current transformer, the temperature of current transformer inside can be caused when bus current is larger in electric system to raise, and then cause the rising of luminotron 2 temperature.The luminous power of luminotron 2 can decline with the rising of temperature, and this changes causing the value of coefficient a and b in P-U relation.
As shown in Figure 6, known through reality test: during 25 DEG C and 70 DEG C, at (U
1, U
2) section, its P-U relation is all linear, but coefficient a, b when 25 DEG C and 70 DEG C time coefficient a ', b ' unequal, coefficient a and b that namely P-U relation is corresponding can vary with temperature and change, and this is unfavorable for the enforcement of the method for transmitting signals of this current transformer.In order to ensure that, when temperature raises, coefficient a and b of constant current driving unit P-U relation used is constant, corresponding increase the electric current of luminotron 2 can be flowed through when temperature raises.Specific implementation method is in constant current driving unit, by voltage U
ibe converted into the thermistor (NTC) that luminotron 2 drive current resistance R used uses negative temperature coefficient, its resistance value can be lower when temperature is higher for such thermistor, thus the electric current flowing through luminotron 2 is increased, automatically to voltage U
i, also just compensate for temperature and raise the luminotron 2 luminous power decline caused, coefficient a, b in its P-U relation can almost remain unchanged.Ensure when temperature variation thus, use this method still can realize high-acruracy survey.
According to the sensitivity of luminotron 2 pairs of temperature, if the luminous power of luminotron 2 is large to responsive to temperature degree, then to select the thermistor that temperature-coefficient of electrical resistance is larger, otherwise select the thermistor that temperature-coefficient of electrical resistance is less when thermistor is selected.
As shown in Figure 7, when the heat-sensitive coefficients test carrying out thermistor, comprise the steps:
Step a, under normal temperature (as 25 DEG C) T1, exports a constant driving DC voltage to constant-current drive circuit.
Step b, utilizes potentiometer to replace thermistor and measures the initial resistivity value R1 of potentiometer.
Step c, the luminous power P1 of record luminotron 2 under temperature T1.
Steps d, uses heating device (as heating cabinet) that the working temperature (using the temperature of luminotron pad as luminotron temperature) of luminotron 2 is increased to T2, and the luminous power P2 of luminotron 2 under being recorded in temperature T2.
Step e, the working temperature keeping luminotron 2 is T2, and constantly reduces the resistance of potentiometer, and now the luminous power of luminotron 2 starts to raise, when the luminous power of luminotron 2 rises to P1, record potentiometer resistance R2 now.
Step f, by calculating the difference of the working temperature of luminotron 2
=T2-T1, and the drop-out value of potentiometer resistance
=R1-R2, calculates the temperature coefficient that thermistor should have, and completes the selection to thermistor according to this principle.
Step 3, primary side 1 parameter is stored in secondary side 6.
By coefficient a, the b in P-U relation and DC reference voltage signal
be stored in the CPU (central processing unit) of signal extraction unit in secondary side 6.
Step 4, calculates secondary side direct voltage reference value and power frequency component effective value.
When equipment works at the scene, after the DC reference signal value that the CPU (central processing unit) circuit in secondary side 6 in signal extraction unit exports photoelectric detection unit and power frequency component sampling, calculate the DC reference signal value after decay
value and the effective value of power frequency component
.
Step 5, calculate primary side 1 power frequency component effective value.
As shown in Figure 1, suppose that the luminous power that luminotron 2 sends is P, the light that luminotron 2 sends successively through joints of optical fibre 3(as FC interface) be coupled into optical fiber 4(as plastic optical fiber), through optical fiber 4 complete transmission laggard enter the photoelectric tube 5 of photo-detector circuit.In the transmission of above-mentioned light signal, each link will cause the decay of luminous power.The luminous power supposing finally to be coupled into photoelectric tube 5 is P ', then P ' meets formula (2) with the relation of P:
, wherein
.
Photo-detector circuit essence is " electric current-voltage " change-over circuit, and the light signal received is converted into current signal by photodetector (photoelectric tube 5) wherein, and current conversion is voltage signal U by recycling feedback resistance
oexport.The input optical signal P ' that can make this photo-detector circuit by the photodetector of " light-electricity " characteristic of selecting the operational amplifier of Low-bias Current, the linearity good and the circuit design method of " zero-bias voltage pattern " and the voltage signal U exported
obetween coincidence formula (3):
.
According to formula (1) ~ formula (3):
,
with
formula (4) can be released:
.Wherein a and b is determined by the P-U characteristic of luminotron 2, and by using the design of thermistor to make the value of a and b remain unchanged;
then represent the luminous burn-in effects of the decay of optical fiber 4 pairs of light signals, coupling attenuation and luminotron 2;
be a constant, it comprises the size of the conversion efficiency of photodetector, the feedback resistance of current-voltage conversion circuit.
In this practical application, if only right
constant current driving unit inputs a DC reference signal
, then obtain formula (5) by formula (4):
.Wherein a, b,
for known number,
can measure in the signal extraction unit of secondary side 6 and obtain, formula (6) can be obtained thus
formula (6)
As shown in Figure 5, for constant current driving unit, the voltage signal of its actual input end input is
.
can be realized producing (DC reference signal as used voltage reference chip REF5025 to export a 2.5V) by hardware mode, the luminous power of corresponding luminotron 2 also with
for benchmark, along with
the change of signal and changing, variation range (U
1, U2) and the maximum current of bus that will measure according to current transformer determines; If the current work scope of measured bus is comparatively large, can improve
value, namely improve the quiescent point of circuit, when the thermistor simultaneously in constant-current drive circuit is selected, select the thermistor that resistance is less.Photo-detector circuit output voltage values U in the secondary side 6 of current transformer
ofor
,
,
all first can sample in the signal extraction unit of secondary side 6, recycling CPU (central processing unit) calculates.According to formula (5), obtain formula (7):
, formula (7) and formula (5) subtract each other and obtain formula (8):
, wherein a is known,
obtained by formula (6),
obtained by the CPU (central processing unit) measurement in signal extraction unit in secondary side 6, so obtain formula (9):
formula (9)
The analog voltage signal of coil output can be obtained by above-mentioned formula (9)
.
Step 6, calculates the bus current effective value of primary side 1.
By the analog voltage signal analyzed the formula (9) that draws in step 5 and calculate
only a multiple proportion with the size of the bus current of flowing through coil (iron-core coil or air core coil), any one in following situation corresponding when the size of this multiple depends on the turn ratio of coil primary and secondary winding used and adopts three kinds of above-mentioned different coils to realize: the size of the design of air core coil integrating circuit or the size of iron-core coil shunt resistance or the transfer resistance of conventional iron core coil in signal conditioning circuit.According to the analog voltage signal that formula (9) calculates
, the CPU (central processing unit) being arranged in secondary side 6 signal extraction unit will
be multiplied by the size that this multiple can calculate bus current.According to the needs of secondary side equipment, CPU (central processing unit) thus the merge cells that the size of bus current exports secondary side to the form of digital quantity can be connect secondary device again; The simulation that signal extraction unit also can export by CPU (central processing unit)
signal directly supplies surveying instrument or protective relaying device after carrying out programming amplifying.
The above is only preferred embodiment of the present invention, and be not restriction the present invention being made to other form, any those skilled in the art may utilize the technology contents of above-mentioned announcement to be changed or be modified as the Equivalent embodiments of equivalent variations.But everyly do not depart from technical solution of the present invention content, any simple modification, equivalent variations and the remodeling done above embodiment according to technical spirit of the present invention, still belong to the protection domain of technical solution of the present invention.
Claims (10)
1. the signal transmitting apparatus for current transformer, comprise the primary side (1) and secondary side (6) that are connected by optical fiber (4), it is characterized in that: in described primary side (1), the input end of the output terminal connection signal conditioning unit of the coil of connection bus, the output terminal of signal condition unit connects the input end of constant current driving unit, and the output terminal of constant current driving unit connects one end of described optical fiber (4);
The input end of other end connecting secondary side (6) the interior photoelectric detection unit of optical fiber (4), the input end of the output terminal connection signal extraction unit of photoelectric detection unit, is carried out the output of signal by the output terminal of signal extraction unit.
2. the signal transmitting apparatus for current transformer according to claim 1, it is characterized in that: described signal extraction unit at least comprises capacitance and CPU (central processing unit), the signal of described photoelectric detection unit is divided into two-way: capacitance of leading up to is connected with CPU (central processing unit), and another road is directly connected with CPU (central processing unit).
3. the signal transmitting apparatus for current transformer according to claim 1 and 2, is characterized in that: described photoelectric detection unit at least comprises: light signal be converted to the photoelectric tube (5) of current signal and the current signal that photoelectric tube (5) is converted to be converted to the current-voltage conversion circuit of voltage signal.
4. the signal transmitting apparatus for current transformer according to claim 1, it is characterized in that: described signal condition unit at least comprises: the voltage reference chip that can generate DC reference voltage, and the power frequency component exported by described coil and reference voltage carry out the signal mixed circuit that mixes.
5. the signal transmitting apparatus for current transformer according to claim 1, is characterized in that: described constant current driving unit at least comprises the transfer resistance that the voltage signal that signal condition unit exports is converted to current signal and the current signal be converted to by transfer resistance carries out driving luminous luminotron (2).
6. the signal transmitting apparatus for current transformer according to claim 5, is characterized in that: described luminotron (2) is communication luminotron.
7. the signal transmitting apparatus for current transformer according to claim 5, is characterized in that: described transfer resistance is the thermistor of negative temperature coefficient.
8. the method for transmitting signals of the signal transmitting apparatus for current transformer according to any one of claim 1 ~ 7, is characterized in that: comprise the steps:
Step 1, exports the different DC voltage of many group numerical value to constant current driving unit, drives luminotron (2) with different power light-emittings, obtain many groups U-P numerical value of luminotron (2);
Step 2, the many groups obtained by step 1 U-P numerical fitting obtains the P-U relation curve of the luminous power-driving voltage of luminotron (2):
, and by coefficient a, b, calculate the temperature coefficient of thermistor in constant current driving unit according to heat-sensitive coefficients method of testing;
Step 3, by coefficient a, the b in P-U relation curve in step 2 and the DC reference voltage signal by the voltage reference chip generation in signal conditioning circuit
value be stored in the CPU (central processing unit) of signal extraction unit in secondary side (6);
Step 4, CPU (central processing unit) circuit samples respectively to the signal that photoelectric detection unit exports, and calculates the DC reference signal value of decay after optical fiber (4) transmission
value and the effective value of power frequency component
;
Step 5, according to the power frequency component that power frequency component computing formula calculates first siding ring output or obtained by signal condition cell translation
;
Step 6, according to the power frequency component that step 5 calculates
calculate the effective value of bus.
9. method for transmitting signals according to claim 8, is characterized in that: the power frequency component computing formula described in step 5 is:
Wherein, a, b are respectively the P-U relation curve of luminotron (2)
coefficient,
the DC reference voltage produced for using voltage reference chip in signal condition unit,
,
be respectively CPU (central processing unit) to sample the reference voltage after the decay that obtains
and power frequency component.
10. method for transmitting signals according to claim 8, is characterized in that: the heat-sensitive coefficients method of testing described in step 2, comprises the steps:
Step a, under normal temperature T1, exports a constant driving DC voltage to constant-current drive circuit;
Step b, utilizes potentiometer to replace thermistor and measures the initial resistivity value R1 of potentiometer;
Step c, record luminotron (2) the luminous power P1 under temperature T1;
Steps d, uses heating device that the working temperature of luminotron (2) is increased to T2, and the luminous power P2 of luminotron (2) under being recorded in temperature T2;
Step e, the working temperature keeping luminotron (2) is T2, and constantly reduces the resistance of potentiometer, and now the luminous power of luminotron 2 starts to raise, when the luminous power of luminotron (2) rises to P1, record potentiometer resistance R2 now;
Step f, by calculating the difference of the working temperature of luminotron (2)
=T2-T1, and the drop-out value of potentiometer resistance
=R1-R2, calculates the temperature coefficient that thermistor should have, and completes the selection to thermistor according to this principle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510102017.2A CN104655908B (en) | 2015-03-09 | 2015-03-09 | A kind of method for transmitting signals for current transformer |
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| CN105510862A (en) * | 2016-01-13 | 2016-04-20 | 济南大学 | Voltage transformer state monitoring system and method |
| CN106093510A (en) * | 2016-08-17 | 2016-11-09 | 山东理工大学 | A kind of mutual inductor secondary side signals conditioning device and method |
| CN106373380A (en) * | 2016-08-17 | 2017-02-01 | 山东理工大学 | Electronic current transformer signal linear transmission device and method |
| CN109270318A (en) * | 2018-10-10 | 2019-01-25 | 山东理工大学 | A kind of the current transducer signal Transmission system and transmission method of Wide measuring range |
| CN109387687A (en) * | 2018-11-09 | 2019-02-26 | 福州大学 | A kind of the energy-conserving photoelectric Transmission system and method for new-style electronic mutual inductor |
| CN110082582A (en) * | 2019-03-21 | 2019-08-02 | 北京交通大学 | A kind of current sensor based on fibre-optic transmission system (FOTS) |
| CN112763784A (en) * | 2020-12-20 | 2021-05-07 | 复旦大学 | Current detection device and method |
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| CN105510862A (en) * | 2016-01-13 | 2016-04-20 | 济南大学 | Voltage transformer state monitoring system and method |
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| CN106093510A (en) * | 2016-08-17 | 2016-11-09 | 山东理工大学 | A kind of mutual inductor secondary side signals conditioning device and method |
| CN106373380A (en) * | 2016-08-17 | 2017-02-01 | 山东理工大学 | Electronic current transformer signal linear transmission device and method |
| CN106093510B (en) * | 2016-08-17 | 2018-08-28 | 山东理工大学 | A kind of mutual inductor secondary side signals Opsonizing method |
| CN106373380B (en) * | 2016-08-17 | 2019-06-14 | 山东理工大学 | A kind of linear transfer method of electronic current mutual inductor signal |
| CN109270318A (en) * | 2018-10-10 | 2019-01-25 | 山东理工大学 | A kind of the current transducer signal Transmission system and transmission method of Wide measuring range |
| CN109270318B (en) * | 2018-10-10 | 2020-10-13 | 山东理工大学 | Current transformer signal transmission system and method with wide measurement range |
| CN109387687A (en) * | 2018-11-09 | 2019-02-26 | 福州大学 | A kind of the energy-conserving photoelectric Transmission system and method for new-style electronic mutual inductor |
| CN110082582A (en) * | 2019-03-21 | 2019-08-02 | 北京交通大学 | A kind of current sensor based on fibre-optic transmission system (FOTS) |
| CN112763784A (en) * | 2020-12-20 | 2021-05-07 | 复旦大学 | Current detection device and method |
| CN112763784B (en) * | 2020-12-20 | 2022-05-20 | 复旦大学 | Current detection device and method |
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