The method for self-calibrating of optical voltage sensor
Technical field
The present invention relates to a kind of method for self-calibrating of sensor.
Background technology
Voltage transformer (VT) is the visual plant that carries out voltage measurement in the electric system, and safe, the reliable and economical operation of its measuring accuracy and operational reliability and electric system is closely related.The voltage transformer (VT) that uses mainly contains electromagnetic potential transformer, capacitive divided voltage mutual inductor and electronic type voltage transformer at present.Along with the development of intelligent grid, electronic type voltage transformer is more and more paid close attention to and is used.Optical voltage transformer adopts Pockels electrooptical effect principle, it has no frequency band and measures restriction, can accurately reflect the characteristics such as full voltage information that comprise aperiodic component, be optimal electronic type voltage transformer, is the main direction of electronic type voltage transformer development.
Optical voltage sensor is the core component of optical voltage transformer, and the temperature of its measuring accuracy problem of floating is the one of the main reasons that optical voltage transformer is difficult to practicability always.According to the optical voltage sensing principle, optical voltage sensor belongs to the open loop measuring system.The high measurement accuracy of open loop measuring system depends on the high stability of sensor-based system each several part parameter, and being subjected to Temperature Influence of any part of sensor-based system and changing must be brought the drift of voltage sensor output signal, thereby produces measuring error.
Improving the most direct method of optical voltage sensor measuring accuracy is to adopt the structure and material of parameter stability, but because aspects such as technology and cost, this method also is difficult to realize at present.The method that improves the optical voltage sensor measuring accuracy at present mainly is compensation method.These compensation methodes generally all are that certain link of sensor-based system is taked the temperature compensation measure.Although these compensation methodes have improved the measuring accuracy of optical sensor to a certain extent, there is very big dispersiveness and uncertain in temperature to the influence of sensor-based system.
In sum, the consistance of existing optical voltage sensor measuring accuracy and long-term temperature stability are difficult to satisfy electric system to the requirement of voltage measurement precision.
Summary of the invention
The objective of the invention is in order to solve the problem of existing optical voltage sensor measuring accuracy temperature stability difference, thereby a kind of method for self-calibrating of optical voltage sensor is provided.
A kind of optical voltage sensor, it comprises optical voltage sensing unit, reference voltage source and far-end acquisition module, the upper end electrode of optical voltage sensing unit connects a voltage signal input end to be measured of this optical voltage sensor, this input end is non-earth terminal, the earth terminal of reference voltage source is another voltage input end to be measured of this optical voltage sensor, this input end is earth terminal, and the reference voltage signal output terminal of reference voltage source connects the lower end electrode of optical voltage sensing unit; The frequency of the voltage signal of reference voltage source output is greater than the frequency of voltage signal to be measured; The far-end acquisition module is gathered the reference voltage signal of reference voltage source output, and described far-end acquisition module converts the voltage signal that collects to calibration voltage output terminal that light pulse signal exports optical voltage sensor to; The light source input end of optical voltage sensing unit is the light source input end of this optical voltage sensor; The induced signal output terminal of optical voltage sensing unit is the optical voltage sensing signal output part of this optical voltage sensor; The reference voltage output end of far-end acquisition module is the reference voltage output end of this optical voltage sensor.
Realize the method for self-calibrating of above-mentioned optical voltage sensor, a voltage signal input end to be measured and the tested voltage source output voltage signal U of optical voltage sensor
1Non-earth terminal connect; The earth terminal of reference voltage source is connected with tested voltage source earth terminal; The far-end acquisition module is gathered the output voltage signal U of reference voltage source
2, described far-end acquisition module converts the voltage signal that collects to light pulse signal, is transmitted through the fiber to the secondary converter of voltage transformer (VT) then; The light source that the secondary converter of described voltage transformer (VT) sends is transmitted through the fiber to the light source input end of optical voltage sensing unit, and the optical voltage sensing unit is sense voltage signal U simultaneously
1With U
2, and be transmitted through the fiber to the secondary converter of voltage transformer (VT); The secondary converter of voltage transformer (VT) is handled the analog optical signal that receives, and obtains the tested voltage signal of induction and induction reference voltage signal;
This secondary converter also receives the light pulse signal of the calibration voltage output terminal output of optical voltage sensor, by obtaining reference voltage signal after the digital demodulation;
This secondary converter also utilizes the discrete Fourier algorithm to realize the induction reference voltage signal of acquisition and the effective value of reference voltage signal are calculated, by to the induction reference voltage signal that calculates and the real-time comparison of reference voltage signal effective value, obtain the output self calibration coefficient of optical voltage sensor; Then, utilize this self calibration coefficient that the tested voltage signal of induction of optical voltage sensing unit sensitivity is revised, obtain tested voltage output signal not influenced by ambient temperature;
This secondary converter also will carry out the data framing according to the FT3 form to tested voltage signal, adopt asynchronous system to be sent to merge cells by optical fiber.
Described method is specially:
It is f that reference voltage source produces frequency
2, effective value is U
2Voltage signal, the reference voltage signal that the secondary converter receives from the reference voltage output end of optical voltage sensor is through after the demodulation process, the voltage signal that obtains is expressed as:
Wherein: n is the counting of data sample; t
nIt is the sampling time of n data;
The initial phase of the reference voltage signal of gathering for the far-end acquisition module;
The secondary converter receives from the optical voltage sensing signal output part of optical voltage sensor
The responsive tested voltage signal of induction that obtains in optical voltage sensing unit and induction reference voltage signal, and this signal is carried out data handle obtain responding to tested voltage and are:
Obtaining responding to reference voltage is:
Wherein: Δ k is the output coefficient variable quantity that external influence factor such as environment temperature causes the optical voltage sensing unit, and is irrelevant with the sense voltage signal frequency;
Initial phase for the tested voltage signal of induction of optical voltage sensing unit sensitivity; U
1Be the effective value of tested voltage source output voltage signal,
Initial phase for the induction reference voltage signal of optical voltage sensing unit sensitivity; f
1Frequency for tested voltage source output voltage signal;
External influence factors such as environment temperature cause that the output coefficient variation delta k of optical voltage sensing unit calculates by following formula:
Wherein: U
2The effective value of ' induction the reference voltage signal that obtains for optical voltage sensing unit sensitivity;
Adopt above-mentioned coefficient that the tested voltage signal of induction of optical voltage sensing unit sensitivity is revised, obtain output voltage signal not influenced by ambient temperature:
In the formula: (1+ Δ k) is the self calibration coefficient of optical voltage sensor output signal.
The optical voltage sensing unit is based on the Pockels electrooptical effect principle responsive tested voltage signal of induction and the reference voltage signal of obtaining simultaneously.
Beneficial effect: the present invention has realized the self-calibration function of optical voltage sensor by the design basis voltage source, solves the problem of existing optical voltage sensor measuring accuracy temperature stability difference.Through test, measuring accuracy has reached IEC0.2 level measuring requirement in-40~60 ℃ temperature range.
Description of drawings
Fig. 1 is structural representation of the present invention.
Embodiment
Embodiment one, in conjunction with Fig. 1 this embodiment is described, a kind of optical voltage sensor, it comprises optical voltage sensing unit 2-1, reference voltage source 2-2 and far-end acquisition module 2-3, the upper end electrode of optical voltage sensing unit 2-1 connects a voltage signal input end to be measured of this optical voltage sensor 2, this input end is non-earth terminal, the earth terminal of reference voltage source 2-2 is another voltage input end to be measured of this optical voltage sensor 2, this input end is earth terminal, and the reference voltage signal output terminal of reference voltage source 2-2 connects the lower end electrode of optical voltage sensing unit 2-1; The frequency of the voltage signal of reference voltage source 2-2 output is greater than the frequency of voltage signal to be measured; Far-end acquisition module 2-3 gathers the reference voltage signal of reference voltage source 2-2 output, and described far-end acquisition module 2-3 converts the voltage signal that collects to calibration voltage output terminal that light pulse signal exports optical voltage sensor to; The light source input end of optical voltage sensing unit 2-1 is the light source input end of this optical voltage sensor 2; The induced signal output terminal of optical voltage sensing unit 2-1 is the optical voltage sensing signal output part of this optical voltage sensor 2; The reference voltage output end of far-end acquisition module 2-3 is the reference voltage output end of this optical voltage sensor 2.
The method for self-calibrating of embodiment two, realization embodiment one described a kind of optical voltage sensor, a voltage signal input end to be measured of optical voltage sensor 2 and tested voltage source 1 output voltage signal U
1Non-earth terminal connect; The earth terminal of reference voltage source 2-2 is connected with tested voltage source 1 earth terminal; Far-end acquisition module 2-3 gathers the output voltage signal U of reference voltage source 2-2
2, described far-end acquisition module 2-3 converts the voltage signal that collects to light pulse signal, is transmitted through the fiber to the secondary converter 3 of voltage transformer (VT) then; The light source that the secondary converter 3 of described voltage transformer (VT) sends is transmitted through the fiber to the light source input end of optical voltage sensing unit 2-1, and optical voltage sensing unit 2-1 is sense voltage signal U simultaneously
1With U
2, and be transmitted through the fiber to the secondary converter 3 of voltage transformer (VT); 3 pairs of analog optical signals that receive of the secondary converter of voltage transformer (VT) are handled, and obtain the tested voltage signal of induction and induction reference voltage signal;
This secondary converter 3 also receives the light pulse signal of the calibration voltage output terminal output of optical voltage sensor 2, by obtaining reference voltage signal after the digital demodulation;
This secondary converter 3 also utilizes the discrete Fourier algorithm to realize the induction reference voltage signal of acquisition and the effective value of reference voltage signal are calculated, by to the induction reference voltage signal that calculates and the real-time comparison of reference voltage signal effective value, obtain the output self calibration coefficient of optical voltage sensor 2; Then, utilize this self calibration coefficient that the tested voltage signal of induction of optical voltage sensing unit 2-1 sensitivity is revised, obtain tested voltage output signal not influenced by ambient temperature;
This secondary converter 3 also will carry out the data framing according to the FT3 form to tested voltage signal, adopt asynchronous system to be sent to merge cells 4 by optical fiber.
The method that calculating and the self-calibration function of correction factor are realized is described further below.
It is f that reference voltage source 2-2 produces frequency
2, effective value is U
2Voltage signal, far-end acquisition module 2-3 gathers this voltage signal and converts light pulse signal to and is sent to secondary converter 3, through after the demodulation process, the voltage signal that obtains can be expressed as:
Wherein:
N is the counting of data sample; t
nIt is the sampling time of n data;
Voltage signal U for far-end acquisition module 2-3 collection
2Initial phase.
The frequency f of the voltage signal that reference voltage source 2-2 produces
2Known, effective value U
2Adopt the discrete Fourier algorithm to calculate, take to increase calculating sample number and windowing process in the calculating and reduce frequency jitter to the influence of effective value calculating.Because far-end acquisition module 2-3 gathers the influence that the voltage signal that obtains is not subjected to extraneous factors such as environmental problem, can think that far-end acquisition module 2-3 gathers the voltage signal that obtains and is the voltage signal U that reference voltage source 2-2 produces
2
Optical voltage sensing unit 2-1 is sense voltage signal U simultaneously
1With voltage signal U
2, and be transmitted through the fiber to secondary converter 3, after handling through data, the voltage signal that obtains can be expressed as respectively:
Wherein: Δ k is the output coefficient variable quantity that external influence factor such as environment temperature causes optical voltage sensing unit 2-1, and is irrelevant with the sense voltage signal frequency;
Voltage signal U for optical voltage sensing unit 2-1 sensitivity
1Initial phase;
Voltage signal U for optical voltage sensing unit 2-1 sensitivity
2Initial phase; f
1Be tested
voltage source 1 output voltage signal U
1Frequency.
The voltage signal U of optical voltage sensing unit 2-1 sensitivity
2The effective value U of the voltage signal that obtains
2' adopt the discrete Fourier algorithm to calculate, take to increase calculating sample number and windowing process in the calculating and reduce frequency jitter to the influence of effective value calculating.
External influence factors such as environment temperature cause that the output coefficient variation delta k of optical voltage sensing unit 2-1 can calculate by following formula:
Wherein: U
2The effective value of ' induction the reference voltage signal that obtains for optical voltage sensing unit (2-1) sensitivity;
To optical voltage sensing unit 2-1 while sense voltage signal U
1The voltage signal u that obtains
1' revise the output voltage signal that not influenced by extraneous factors such as environment temperature:
In the formula: (1+ Δ k) is the self calibration coefficient of optical voltage sensor (2) output signal;
If tested voltage source 1 output voltage signal U
1Except comprising fundamental frequency, also comprise other higher hamonic wave frequency, above-mentioned computing method are suitable equally.
Optical voltage sensor of the present invention compared with prior art has following feature and advantage:
1, the present invention has realized the self-calibration function of optical voltage sensor by the design basis voltage source, solves the problem of existing optical voltage sensor measuring accuracy temperature stability difference.
2, the present invention adopts the discrete Fourier algorithm to obtain the effective value of voltage signal, reduces frequency jitter to the influence that effective value calculates by increasing calculating sample number and windowing process, has improved the stability of self calibration coefficient.
Optical current sensor of the present invention has solved the shortcoming of optical voltage sensor measurement result temperature influence, and through test, measuring accuracy has reached IEC0.2 level measuring requirement in-40~60 ℃ temperature range.