CN109270318B - Current transformer signal transmission system and method with wide measurement range - Google Patents
Current transformer signal transmission system and method with wide measurement range Download PDFInfo
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- CN109270318B CN109270318B CN201811179206.XA CN201811179206A CN109270318B CN 109270318 B CN109270318 B CN 109270318B CN 201811179206 A CN201811179206 A CN 201811179206A CN 109270318 B CN109270318 B CN 109270318B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
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- H04B10/25—Arrangements specific to fibre transmission
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Abstract
A current transformer signal transmission system and a transmission method with a wide measurement range belong to the field of electrical engineering measurement. Including high pressure side and the low pressure side by optical fiber connection, its characterized in that: the output end of the current transformer is simultaneously connected with the input ends of the interval information judging module and the signal conditioning module, the output end of the signal conditioning module is connected with the input end of the signal driving module to be tested, the output end of the interval information judging module is respectively connected with the input ends of the interval information driving module and the variable current limiting resistance module, and the variable current limiting resistance module changes the resistance value output to the signal driving module to be tested according to different signals output by the interval information judging module. In the current transformer signal transmission system and the current transformer signal transmission method with the wide measurement range, the interval information of the output signal of the current transformer is judged by arranging the interval information judgment module, and the waveform amplitude of the signal to be detected during transmission is changed through the interval information, so that the signal-to-noise ratio of the signal to be detected under the condition of smaller amplitude is improved.
Description
Technical Field
A current transformer signal transmission system and a transmission method with a wide measurement range belong to the field of electrical engineering measurement.
Background
In the prior art, a Current Transformer mainly plays a role in measurement and protection in an application process, wherein an air core coil is mostly used as a high-voltage side sensor device for a Current Transformer for protection at present, and a Low-Power Current Transformer (LPCT for short) is mostly used as a Low-Power Current Transformer (LPCT) for measurement as a high-voltage side sensor device, because the LPCT has a very wide linearity range, for example, the ratio error and the phase error of the Current LPCT can reach 0.2 level requirements in a 20-time rated Current range under a steady state, the LPCT can fully take dual functions of measurement and protection, and in view of the reason and cost factors, electronic Current Transformer products on the market at present are selected from high-voltage side sensor heads, and many enterprises use a single LPCT scheme.
In terms of a signal converter on a high-voltage side, currently, a light emphasis system, a (V/F) conversion type and an analog-to-digital (a/D) conversion type are mainly used, wherein the frequency bands capable of being transmitted by voltage-frequency conversion and analog-to-digital conversion are both limited, for protection and measurement integration, a light intensity modulation type is used as a high-voltage side signal conversion scheme, a/D sampling is not needed on the high-voltage side, an analog voltage signal representing bus current can be directly used for driving an LED to emit light, the continuous LED light intensity is used for representing the bus current signal, and the frequency band of the current LED can reach 100MHz, so that the mode can easily realize signal transmission with the bandwidth of 5MHz, which is very beneficial to traveling wave protection. Therefore, the design of the electronic current transformer by using the method has obvious advantages in cost and transmission frequency band compared with the current products on the market.
However, the use of a single LPCT and the use of an intensity modulation scheme has the following disadvantages: the range of the voltage signal of the LPCT which reflects the bus current and is output by the sampling resistor is limited by the voltage of the high-voltage side circuit power supply, for example, if the high-voltage side circuit uses a +5V power supply, for the integrated current transformer for measuring and protecting 5P20 precision, when the rated current is 300A, the protection multiple is 20, the current signal in the range of 0-6000A is reflected corresponding to the voltage signal in the range of 0-5V, and if the design circuit uses a 5V peak value (a) (if the design circuit uses a 5V peak value (b) (b))V pp ) Representing a 6000A current, then a 250mV dynamic range voltage is required for a 300A current rating, and a 15A current (5% current rating) is represented using a 12.5mV dynamic range.
Generally, when a current transformer is operated, the probability of occurrence of a fault is extremely low, and therefore the current transformer is in a use state for measurement for most of the time, but as is known from the above, when a 15A current is measured by using a signal with such a small dynamic range, the signal-to-noise ratio is low, and therefore the measurement accuracy of the signal is also low, and it is seen that, for a current transformer in which protection and measurement are integrated by using one LPCT, ensuring a large measurement range and ensuring a high accuracy, particularly the measurement accuracy of a small current, within the range is difficult to achieve both.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the current transformer signal transmission system and the transmission method overcome the defects of the prior art, judge the interval information of the output signal of the current transformer by arranging the interval information judgment module, change the waveform amplitude of the signal to be detected during transmission through the interval information and improve the signal-to-noise ratio under the condition of smaller amplitude of the signal to be detected in the wide measurement range.
The technical scheme adopted by the invention for solving the technical problems is as follows: this wide measuring range's current transformer signal transmission system includes high pressure side and low pressure side by optical fiber connection, and current transformer connects at the high pressure side, transmits the signal of current transformer output to the low pressure side by the high pressure side through optic fibre, its characterized in that: the output end of the current transformer is connected with the input ends of the rectification filtering module and the signal conditioning module at the same time, the output end of the rectification filtering module is connected with the input end of the interval information judgment module, the output end of the signal conditioning module is connected with the input end of the signal driving module to be tested, the signal driving module to be tested drives a second light-emitting diode in the signal driving module to send optical signals with different powers according to voltage signals output by the signal conditioning module, and the optical signals are connected with the input end of the signal photoelectric conversion module to be tested at the low-voltage side through a second optical fiber;
the output end of the interval information judging module is respectively connected with the input ends of the interval information driving module and the variable current limiting resistance module, the interval information driving module drives a first light emitting diode in the interval information driving module to emit light signals with different sections of power according to signals output by the interval information judging module, and the light signals are connected with the input end of the low-voltage side interval signal photoelectric conversion module through a first optical fiber; the variable current limiting resistance module changes the resistance value output to the signal driving module to be tested according to different signals output by the interval information judging module;
and on the low-voltage side, the output end of the interval signal photoelectric conversion module is also connected with the input end of the signal photoelectric conversion module to be detected.
Preferably, the signal conditioning module includes a reference voltage generating module for generating a reference signal, and a signal mixing module for mixing the reference signal with a signal output by the current transformer.
Preferably, a phase shift module for delaying the output signal of the signal conditioning module is further disposed between the signal conditioning module and the signal driving module to be tested.
Preferably, a linear light-emitting driving circuit for driving the second light-emitting diode to work is arranged in the signal driving module to be tested, and the linear light-emitting driving circuit is obtained by the voltage of the signal conditioning module and the resistance output by the variable current-limiting resistance module.
Preferably, the interval information judging module comprises a plurality of voltage-stabilizing tubes with voltage-stabilizing values increasing in sequence, the voltage-stabilizing tubes are respectively connected with corresponding resistors in series to form corresponding voltage-stabilizing loops, the output ends of the voltage-stabilizing values after the voltage-stabilizing loops are connected in parallel are simultaneously connected with the input end of the analog adder, and the output end of the analog adder is connected with the interval information driving module; the voltage stabilizing output end of the voltage stabilizing tube is respectively connected with different input ends of the variable current limiting resistor module.
Preferably, the variable current-limiting resistor module is a digital potentiometer, and a voltage-dividing resistor is further arranged between the output end of the voltage-stabilizing tube and the input end of the digital potentiometer.
A transmission method realized by a current transformer signal transmission system with a wide measurement range is characterized in that: the method comprises the following steps:
a, dividing an output signal of a current transformer into a plurality of current intervals according to the measuring range of the current transformer;
step b, the current transformer outputs a voltage signal, an interval information determining process and a to-be-detected signal conditioning process are simultaneously executed according to the voltage signal output by the current transformer, the interval information of the output signal of the current transformer is obtained by executing the interval information determining process, and a to-be-transmitted signal output by the current transformer is obtained by executing the to-be-detected signal conditioning process;
step c, respectively sending the interval information of the output signal of the current transformer and the signal to be transmitted output by the current transformer to a secondary side through the first optical fiber and the second optical fiber;
d, converting the optical signal sent by the optical fiber by the interval signal photoelectric conversion module to obtain interval information, and transmitting the interval information to the signal photoelectric conversion module to be detected;
step e, converting the optical signal sent by the photoelectric conversion module of the signal to be detected through the optical fiber to obtain a signal to be detected, then processing the converted signal to be detected according to the interval information sent by the photoelectric conversion module of the interval signal, and restoring the signal to be detected when the signal to be detected is sent to the driving module of the signal to be detected;
and f, the photoelectric conversion module of the signal to be detected performs signal separation on the signal to be detected, and finally restores the signal to be transmitted output by the current transformer.
Preferably, the section information determining process includes the following steps:
b-1, sending the voltage signal output by the current transformer to a rectification filtering module for rectification filtering;
step b-2, the interval information judgment module determines the interval of the voltage signal output by the current transformer and outputs corresponding signals to the interval information driving module and the variable current limiting resistance module respectively;
step b-3, the interval information driving module judges the output voltage of the module according to the interval information, and forms a constant current source through a current limiting resistor in the interval information driving module to drive the first light emitting diode to work and send out an optical signal with the power matched with the interval information;
the variable current limiting resistance module outputs a corresponding resistance value to the signal driving module to be tested according to the output signal sent by the interval information judging module, and the resistance value is used as a current limiting resistance of a linear light emitting driving circuit formed in the signal driving module to be tested.
Preferably, the signal conditioning process to be measured includes the following steps:
b' -1, sending a voltage signal output by the current transformer to a signal conditioning module, and superposing a reference voltage in the signal conditioning module through a signal mixing module to form a mixed signal;
b' -2, the mixed signal enters a phase shifting module for phase shifting;
and b' -3, the signal to be detected output by the phase-shifting module is used as a driving power supply and is sent to the signal to be detected driving module, and the signal to be detected and the input end of the variable current-limiting resistance module organize a signal to form a linear light-emitting driving circuit for driving the second light-emitting diode to work.
Compared with the prior art, the invention has the beneficial effects that:
1. in the current transformer signal transmission system and the transmission method with the wide measurement range, the interval information of the output signal of the current transformer is judged and the variable current-limiting resistance module is controlled to output different resistance values according to the signal size of the current transformer by arranging the interval information judgment module, particularly, under the condition that the amplitude value output by the current transformer is smaller, the numerical value of the dynamic range of the driving current for driving the second light-emitting diode to emit light is increased, so that the dynamic range of the optical signal corresponding to the signal to be detected is increased, the signal-to-noise ratio of the signal to be detected under the condition that the amplitude value is smaller is improved, and the transmission precision of the current transformer is increased.
2. The electronic current transformer which simultaneously realizes measurement and protection on a single sensing head improves the measurement precision of small current on the premise of ensuring a large measurement range, thereby realizing the high-precision measurement of a full-range current range.
3. In the application, the detection of the current by the interval information judgment and measurement module and the change of the resistance by the variable current limiting resistance module are not completed by using the CPU, the adjustment is completed by using the electrical characteristics of the circuit to match with the logic circuit, and the method has the advantages of high instantaneity, high reliability and low cost.
4. The introduction of the phase shift module enables the size adjustment of the current limiting resistor suitable for the light emitting of the LED to be completed in advance before the signal to be detected really drives the LED to emit light, so that the problem that the error is introduced to the signal to be detected due to the adjustment of the current limiting resistor does not exist in the whole system.
Drawings
Fig. 1 is a schematic block diagram of a current transformer signal transmission system with a wide measurement range.
Fig. 2 is a flow chart of a signal transmission method of a current transformer with a wide measurement range.
Detailed Description
FIGS. 1-2 illustrate preferred embodiments of the present invention, and the present invention will be further described with reference to FIGS. 1-2.
As shown in fig. 1, a current transformer signal transmission system with a wide measurement range includes a high-voltage side and a low-voltage side, the high-voltage side and the low-voltage side are connected by an optical fiber, wherein the high-voltage side includes a low-power current transformer (LPCT), a rectification filter module, a signal conditioning module, an interval information judgment module, a phase shift module, an interval information judgment module, a variable current limiting resistance module and a signal driving module to be detected, and the low-voltage side includes a current interval photoelectric conversion module and a signal photoelectric conversion module to be detected.
In the high-voltage side, the output end of the LPCT is respectively connected with the input end of a rectifying and filtering module and the input end of a signal conditioning module, the output end of the rectifying and filtering module is connected with the input end of an interval information judging module, the output end of the interval information judging module is simultaneously connected with the input ends of an interval information driving module and a variable current limiting resistance module, the output end of the interval information driving module drives a light-emitting diode to emit light, and the light-emitting diode is marked as a first light-emitting diode and used for outputting interval information of a bus current signal. The output end of the variable current limiting resistance module and the output end of the phase shifting module are respectively connected with the input end of the signal driving module to be tested, the other light emitting diode of the signal driving module to be tested emits light, and the light emitting diode is marked as a second light emitting diode and used for outputting a signal to be tested reflecting a bus current signal.
In the low voltage side, two photodiodes are provided: the photoelectric conversion device comprises a first photodiode and a second photodiode, wherein the first photodiode is connected to the input end of a current interval photoelectric conversion module, the second photodiode is connected to the input end of a signal to be detected photoelectric conversion module, the output end of the current interval photoelectric conversion module is also connected to the input end of the signal to be detected photoelectric conversion module, and the output end of the signal to be detected photoelectric conversion module is connected to secondary equipment. The first photodiode is connected with the first light-emitting diode on the high-voltage side through a first optical fiber, and the second photodiode is connected with the second light-emitting diode through a second optical fiber.
As shown in fig. 2, the signal transmission method implemented by the current transformer signal transmission system with the wide measurement range includes the following steps:
in step 1001, the output signal of the LPCT is divided into a plurality of voltage intervals according to the measuring range of the LPCT.
Dividing the total range into a plurality of current sections, e.g. based on the range of the bus currentI 1 ~I 2 ，I 2 ~I 3 ，……I n-1 ~I n While due to the voltage signal output by the LPCTU 1 Directly reflecting the magnitude of bus current and corresponding to the voltage segments to obtain multiple LPCT outputs, e.g.U 1 - 1 ~U 1-2 ，U 1-2 ~U 1-3 ，……U 1-（n-1） ~U 1-n 。
For example, the LPCT is divided into a plurality of current measuring sections 3A-100A, 100A-500A and more than 500A according to the measuring range of a certain model LPCT, and the voltage signal output by the LPCT is correspondingly obtainedU 1 The corresponding voltage section of (a): 3V to 10V, 10V to 20V and more than 20V.
In step 1002, the LPCT outputs a voltage signal, and executes an interval information determination process and a signal conditioning process according to the voltage signal output by the LPCT.
The section information determination process comprises the following steps:
and step 1003-1, sending the voltage signal output by the LPCT to a rectification filtering module.
Voltage signal output by LPCTU 1 The voltage signals enter a rectification filter module for rectification and filtering to obtain direct current voltage signalsU 2 . The rectifying module adopts a rectifying diode to realize rectification, and because the rectifying diode has voltage drop, when the bus current is small, namely a voltage signalU 1 When the voltage is less than a certain value, the rectifying and filtering module has the condition of no signal output, and the voltage signal at the momentU 2 Is 0.
And step 1003-2, the interval information judgment module determines the located interval and outputs a corresponding signal.
Voltage signal output by rectifying and filtering moduleU 2 Entering a section information judgment module, and comparing the voltage signal by the section information judgment moduleU 2 Is judged according to the voltage signalU 2 Outputs different voltage signals.
As can be seen from the above, the voltage signal output to the LPCT is knownU 1 Is segmented so that when the voltage signal is appliedU 1 Voltage signal obtained after rectification and filteringU 2 A corresponding number of voltage intervals will likewise be obtainedU 2 - 1 ~U 2-2 ，U 2-2 ~U 2-3 ，……U 2-（n-1） ~U 2-n . The interval information judging module judges the interval information according to the voltage signalU 2 The voltage section can obtain voltage signals correspondinglyU 2 And the voltage section is further used for obtaining the current section of the bus current. The interval information judging module then judges the voltage signal according to the voltage signalU 2 The voltage signal with different values is output by different voltage sections.
The section information judging module can be realized by the following modes: taking a plurality of voltage-stabilizing tubes, the number of the voltage-stabilizing tubes and voltage signals output by the LPCTU 1 The number of the divided voltage sections is consistent, and the voltage stabilizing values of the voltage stabilizing tubes are sequentially increased. The LPCT is transfused as described aboveOutput voltage signalU 1 The division into three voltage segments: 3V to 10V, 10V to 20V and more than 20V, therefore three voltage-stabilizing tubes are arrangedVD1~VD3Voltage stabilizing tubeVD1~VD3The regulated voltage values of (1) are 3V, 7V and 10V, respectively.
Three voltage-stabilizing tubesVD1~VD3The three voltage stabilizing loops are connected in series with corresponding resistors to form three voltage stabilizing loops, the output ends of voltage stabilizing values of the three voltage stabilizing loops are connected in parallel and are simultaneously connected to the input end of the analog adder, and the output end of the analog adder serves as the output end of the interval information judging module. From the above, when the voltage signalU 1 When the voltage is lower than 3V, three voltage-stabilizing tubesVD1~VD3All are in cut-off state, and the interval information judging module has no output signal. When the voltage signalU 1 When the voltage value is 3V-10V, the voltage-stabilizing tube VD1 is reversely broken down and conducted and outputs 3V voltage, and the voltage output by the interval information judgment module is 3V. Similarly, when the voltage signalU 1 When the voltage value is 10V-20V, the voltage output by the interval information judgment module is 3V +7V =10V, and when the voltage signal isU 1 When the voltage value of (2) is 20V or more, the voltage output by the section information determination module is 3V +7V +10V = 20V.
And 1003-3, the interval information judgment module sends output signals to the interval information driving module and the variable current limiting resistance module respectively.
When the interval information judging module outputs the driving signal to the interval information driving module, the voltage signal output by the analog adder is directly sent to the interval information driving module, the voltage value is used as a driving power supply, and the interval information driving module drives the corresponding light emitting diode (first light emitting diode) to emit light. The interval information driving module is provided with a current limiting resistor, a constant current source is obtained through a voltage signal output by the analog adder and the current limiting resistor, and the first light emitting diode is driven to emit light through the constant current source.
It can be seen from the above that, the voltage signal outputted from the analog adder has a value of 0V and a value of 3V (regulator tube)VD1Working), 10V (voltage regulator tube)VD1~VD2Working), 20V (voltage regulator tube)VD1~VD3Work) due toThe voltage signal output by the analog adder has obvious step characteristics, so that the constant current sources driving the first light-emitting diodes to work also have the step characteristics with the same proportion, and the light intensity of the first light-emitting diodes can have obvious difference.
The variable current-limiting resistance module is realized by adopting a digital potentiometer, the voltage-stabilizing output end of the voltage-stabilizing tube is respectively connected into different control signal input ends of the digital potentiometer, and when the voltage-stabilizing tube is cut off or is in reverse breakdown, the corresponding control end of the digital potentiometer obtains level signals (representing digital signals 1 or 0) in different states. Meanwhile, in actual needs, the voltage output by the voltage regulator tube is divided by the voltage dividing circuit according to the specific requirements of technical data of the digital potentiometer, so that the voltage signal finally output to the digital potentiometer is in a voltage range recognizable by the digital potentiometer.
Specifically, the method comprises the following steps: when the three voltage-stabilizing tubes are simultaneously cut off, the state signal received by the digital potentiometer is (0, 0, 0), and similarly, when the three voltage-stabilizing tubes are simultaneously reversely broken down to output voltage, the state signal received by the digital potentiometer is (1, 1, 1), so that the digital potentiometer can output different resistors according to different received state signals. In the signal transmission method, the resistance value of the resistor output by the digital potentiometer is based on the voltage signalU 2 The values (voltage sections) of (a) are sequentially increased. One of the resistance values can be taken as a standard value, and the other resistance values are expressed by multiples (more than 1 or less than 1) of the standard value.
The signal conditioning flow to be tested comprises the following steps:
in step 1004-1, the voltage signal output by the LPCT is sent to a signal conditioning module.
The signal conditioning module comprises a reference voltage generating module and a signal mixing module, and the reference voltage output by the reference voltage generating moduleU DC Voltage signal output from LPCTU 1 The two signals are mixed by the signal mixing module to output mixed signalU 3 . The reference signal generation module can pass through the reference voltage chipThe implementation is carried out; the signal mixing module may be implemented by an integrated operational amplifier.
At step 1004-2, the mixed signal is sent to a phase shift module.
Mixed signalU 3 The phase shift is carried out in a phase shift module which does not change the mixed signalU 3 Is delayed only by a short time (in the order of microseconds) and a phase-shifted mixed signal is obtainedU 4 。
And step 1004-3, sending the signal to be tested output by the phase shifting module to the signal to be tested driving module.
Mixed signal output by phase-shifting moduleU 4 Sending into a signal to be tested driving module and mixing the signalsU 4 And as a driving power supply, the corresponding light emitting diode (second light emitting diode) is driven to emit light by the signal driving module to be detected. In the signal driving module to be tested, a current-limiting resistor is also needed to be used for driving the linear light-emitting driving circuit of the second light-emitting diode to emit light, and the resistance value of the current-limiting resistor is the resistance value of the variable current-limiting resistor module, so that the resistance of the linear light-emitting driving circuit driving the second light-emitting diode to emit light is variable. And a driving circuit for driving the second light-emitting diode to emit light in the signal driving module to be detected at the high-voltage side adopts a constant-current linear light-emitting driving circuit.
The specific embodiment of the linear light emitting driver circuit is described in the patent document with the patent name of an optical signal linear transmission system and an active electronic current transformer, which is filed by the applicant at 2016, 8, 17, and is No. 201610678235.5, and the specific embodiment of the linear light emitting driver circuit is the same as the "optical signal linear transmission system" described in the document, and is not described herein again.
The phase-shifting module can be realized by adopting an all-pass filter which does not change the mixed signalU 3 Of only the mixed signalU 3 Do a time ofTTime delay of (3). A phase shift module is arranged, and the purpose of the phase shift module is to realize time matching with the interval information determination process, namely, when the phase of the mixed signal is shiftedU 4 When the signal to be tested enters the driving module, the variable current limiting resistance module already outputs and mixes the signalU 4 But matched resistance values.
Mixed signalU 3 And a voltage signalU 2 Are all directly reflected in the voltage signalU 1 Mixing the signalsU 4 By mixing signals onlyU 3 Phase shift is obtained, so that the mixed signalU 4 And voltage signalU 2 Are all directly reflected in the voltage signalU 1 In relation to the mix signalU 4 And the current limiting resistor of the linear light-emitting drive circuit for driving the second light-emitting diode to emit light is controlled by the voltage signalU 2 And according to the value rule of the current-limiting resistor, the current-limiting signalU 1 When the current signal is small, the resistance value of the output of the variable current limiting resistance module becomes small, so that the current signal (mixed signal) for driving the second light emitting diode to emit lightU 4 Current limiting resistor) to increase the power (amplitude) of the signal to be measured, and increase the mixed signalU 4 The dynamic range of the corresponding optical signal improves the signal-to-noise ratio of the signal to be measured under the condition of smaller amplitude, so that the mixed signalU 4 The transmission precision of (2) is increased, and the same principle is used as a voltage signalU 1 When the current signal is larger, the resistance value of the output of the variable current limiting resistance module is increased through the control of the variable current limiting resistance module, so that the dynamic range of the current signal for driving the second light-emitting diode to emit light is correspondingly reduced.
The section information output by the section information driving module and the signal to be measured output by the signal to be measured driving module are transmitted to the low-voltage side through respective optical fibers (a first optical fiber and a second optical fiber) and are received by the section signal photoelectric conversion module and the signal to be measured photoelectric conversion module respectively.
The interval signal photoelectric conversion module is provided with a first photodiode, the first photodiode receives the signal of the first optical fiber and converts the signal into a voltage signal, and the interval signal photoelectric conversion module can obtain the voltage signalU 1 The interval information of the variable current-limiting resistance module is obtained, the actual output resistance value of the variable current-limiting resistance module is obtained, the multiple of the amplitude value of the signal to be detected transmitted to the low-voltage side and the actual amplitude value of the signal to be detected increasing (or decreasing) can be further obtained, and the interval signal photoelectric conversion module transmits the multiple value to the signal to be detected photoelectric conversion module.
And a second photodiode is arranged in the photoelectric conversion module of the signal to be detected, receives the optical signal sent by the second optical fiber and converts the optical signal into an electric signal representing the signal to be detected, and carries out secondary conversion on the received and converted signal to be detected according to the multiple value sent by the interval signal photoelectric conversion module, and carries out inverse multiple conversion on the current signal to be detected, thereby obtaining the actual signal to be detected.
And step 1008, obtaining an original signal of the signal to be measured according to the signal to be measured on the actual side.
Since the signal to be measured is attenuated for various reasons during the transmission process through the optical fiber, the signal to be measured finally obtained in step 1007 is actually a mixed signalU 4 The attenuated signal is the mixed signalU 4 ' therefore, the output end of the signal to be measured photoelectric conversion module is connected with a signal separation module, and the mixed signal is separated by the signal separation moduleU 4 ' separation intoU DC ' sum voltage signalU 1 ', voltage signalU DC ' sum voltage signalU 1 Respectively reference voltage signal after transmissionU DC And voltage signalU 1 Due to a reference voltage signalU DC Is a known signal, so by measuring a reference voltage signalU DC And voltage signalU DC The attenuation degree of the' can correspondingly obtain the electric signal to be transmittedU 1 The degree of attenuation during transmission can be calculated to obtain the electric signal to be transmittedU AC And then calculating to obtain the magnitude of the bus current. The signal separation module can be implemented by the prior art, such as sampling the voltage signal by a microprocessor, and then calculating the signals of various frequency components by using an FFT algorithm. And finally sending the obtained original signal of the signal to be detected to secondary equipment.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (7)
1. The utility model provides a wide measuring range's current transformer signal transmission system, includes high pressure side and low pressure side by optical fiber connection, and current transformer connects at the high pressure side, conveys the signal of current transformer output to the low pressure side by the high pressure side through optic fibre, its characterized in that: the output end of the current transformer is connected with the input ends of the rectification filtering module and the signal conditioning module at the same time, the output end of the rectification filtering module is connected with the input end of the interval information judgment module, the output end of the signal conditioning module is connected with the input end of the signal driving module to be tested, the signal driving module to be tested drives a second light-emitting diode in the signal driving module to send optical signals with different powers according to voltage signals output by the signal conditioning module, and the optical signals are connected with the input end of the signal photoelectric conversion module to be tested at the low-voltage side through a second optical fiber;
the output end of the interval information judging module is respectively connected with the input ends of the interval information driving module and the variable current limiting resistance module, the interval information driving module drives a first light emitting diode in the interval information driving module to emit light signals with different sections of power according to signals output by the interval information judging module, and the light signals are connected with the input end of the low-voltage side interval signal photoelectric conversion module through a first optical fiber; the variable current limiting resistance module changes the resistance value output to the signal driving module to be tested according to different signals output by the interval information judging module;
and on the low-voltage side, the output end of the interval signal photoelectric conversion module is also connected with the input end of the signal photoelectric conversion module to be detected.
2. The wide measurement range current transformer signal transmission system of claim 1, wherein: the signal conditioning module comprises a reference voltage generating module for generating a reference signal and a signal mixing module for mixing the reference signal and a signal output by the current transformer.
3. The wide measurement range current transformer signal transmission system of claim 1, wherein: and a phase shifting module for delaying the output signal of the signal conditioning module is also arranged between the signal conditioning module and the signal driving module to be tested.
4. The wide measurement range current transformer signal transmission system of claim 1, wherein: the interval information judging module comprises a plurality of voltage-stabilizing tubes with voltage-stabilizing numerical values increasing in sequence, the voltage-stabilizing tubes are respectively connected with corresponding resistors in series to form corresponding voltage-stabilizing loops, the output ends of the voltage-stabilizing numerical values after the voltage-stabilizing loops are connected in parallel are simultaneously connected with the input end of the analog adder, and the output end of the analog adder is connected with the interval information driving module; the voltage stabilizing output end of the voltage stabilizing tube is respectively connected with different input ends of the variable current limiting resistor module.
5. The wide measurement range current transformer signal transmission system of claim 4, wherein: the variable current limiting resistor module is a digital potentiometer, and a voltage dividing resistor is further arranged between the output end of the voltage stabilizing tube and the input end of the digital potentiometer.
6. A transmission method realized by using the current transformer signal transmission system with wide measurement range of any one of claims 1 to 5, is characterized in that: the method comprises the following steps:
a, dividing an output signal of a current transformer into a plurality of current intervals according to the measuring range of the current transformer;
step b, the current transformer outputs a voltage signal, an interval information determining process and a to-be-detected signal conditioning process are simultaneously executed according to the voltage signal output by the current transformer, the interval information of the output signal of the current transformer is obtained by executing the interval information determining process, and a to-be-transmitted signal output by the current transformer is obtained by executing the to-be-detected signal conditioning process;
step c, respectively sending the interval information of the output signal of the current transformer and the signal to be transmitted output by the current transformer to a secondary side through the first optical fiber and the second optical fiber;
d, converting the optical signal sent by the optical fiber by the interval signal photoelectric conversion module to obtain interval information, and transmitting the interval information to the signal photoelectric conversion module to be detected;
step e, converting the optical signal sent by the photoelectric conversion module of the signal to be detected through the optical fiber to obtain a signal to be detected, then processing the converted signal to be detected according to the interval information sent by the photoelectric conversion module of the interval signal, and restoring the signal to be detected when the signal to be detected is sent to the driving module of the signal to be detected;
and f, the photoelectric conversion module of the signal to be detected performs signal separation on the signal to be detected, and finally restores the signal to be transmitted output by the current transformer.
7. The transmission method according to claim 6, characterized in that: the interval information determining process comprises the following steps:
b-1, sending the voltage signal output by the current transformer to a rectification filtering module for rectification filtering;
step b-2, the interval information judgment module determines the interval of the voltage signal output by the current transformer and outputs corresponding signals to the interval information driving module and the variable current limiting resistance module respectively;
step b-3, the interval information driving module judges the output voltage of the module according to the interval information, and forms a constant current source through a current limiting resistor in the interval information driving module to drive the first light emitting diode to work and send out an optical signal with the power matched with the interval information;
the variable current limiting resistance module outputs a corresponding resistance value to the signal driving module to be tested according to the output signal sent by the interval information judging module, and the resistance value is used as a current limiting resistance of a linear light emitting driving circuit formed in the signal driving module to be tested.
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