CN118130885A - Broadband dynamic current signal high-speed measurement method and system based on optical principle - Google Patents

Abstract

The invention discloses a broadband dynamic current signal high-speed measurement method and a system based on an optical principle, wherein the method comprises the following steps: acquiring an analog voltage signal output by an optical current sensing unit at the moment t; based on the analog voltage signals, respectively performing low-pass analog filtering and band-pass analog filtering to obtain a low-frequency voltage signal and a high-frequency voltage signal which are output by the optical current sensing unit at the moment t; under the triggering of a sampling clock, performing high-precision analog-to-digital conversion on the low-frequency voltage signal, and performing high-speed analog-to-digital conversion on the high-frequency voltage signal to obtain a low-frequency discrete voltage signal and a high-frequency discrete voltage signal; synthesizing a broadband current signal output by the optical current sensing unit according to the Fourier transform results of the low-frequency discrete voltage signal and the high-frequency discrete voltage signal; performing dispersion, quantization and coding on the broadband current signal, and outputting message data; the invention has the advantages that: the problem that a single analog-to-digital conversion device cannot achieve both conversion accuracy and conversion rate is solved.

Description

High-speed measurement method and system for broadband dynamic current signals based on optical principles

Technical Field

The present invention relates to the field of electric power technology, and in particular to a broadband dynamic current signal high-speed measurement method and system based on optical principles.

Background technique

Compared with the traditional AC system, the current measurement equipment currently used in the UHV DC transmission system is mainly zero flux current transformer and all-fiber current transformer. Among them, the all-fiber current transformer has been widely used in the UHV DC transmission system because of its good measurement bandwidth and digital output, which is more in line with the application requirements of the strong smart grid. Limited by the comprehensive consideration of measurement accuracy, measurement speed and data transmission flow, the standard "GB/T 26216.1-2019 DC current measurement device for high-voltage DC transmission system Part 1_Electronic DC current measurement device" stipulates that for high-bandwidth DC control transformers, the sampling frequency is selected as 9.6KHz. However, in recent years, due to the grid-connected operation of a high proportion of new energy and the increase in the switching frequency of power electronic devices, the harmonics generated by photovoltaic grid-connected inverters, wind power converters and other equipment have gradually shifted from low frequency bands to high frequency bands, and the harmonic content of the grid side frequency higher than 2kHz has continued to increase. The power system, especially the UHV DC system, has a certain risk of broadband oscillation, and it is necessary to accurately measure and quickly affect the broadband dynamic signals in the system. Analyzing the sampling law, for a broadband signal, the more sampling values are obtained within a cycle, the more accurate the signal details are, and the more accurate the signal measurement is. Therefore, for power systems with growing broadband signals, the existing all-fiber current transformers can no longer meet the accurate measurement of broadband dynamic signals. It is necessary to effectively improve the measurement speed of DC measurement devices to achieve accurate measurement and rapid perception of broadband dynamic current signals.

Chinese patent publication number CN116500329A discloses a broadband current measurement method, device, system and chip, including the following steps: for measuring the low-frequency part of the current flowing through the conductor through a Hall sensor, and outputting the low-frequency measurement signal vin1 of the Hall sensor; for measuring the high-frequency part of the current flowing through the conductor through a TMR sensor, and outputting the high-frequency measurement signal vin2 of the TMR sensor; for low-pass filtering the low-frequency measurement signal vin1 through a low-frequency path buffer stage, and outputting a low-pass filter signal; for high-pass filtering the high-frequency measurement signal vin2 through a high-frequency path buffer stage, and outputting a high-pass filter signal; for superimposing the low-pass filter signal and the high-pass filter signal through an addition stage, and outputting vout. The signal finally output by the patent application is an analog signal. From the perspective of the sensing principle alone, there are many sensors for broadband signal measurement, such as Rogowski coils, TMR sensors, optical sensors, etc., but these sensors output analog signals. For smart grids, it is necessary to digitize analog signals to facilitate the use of many back-end measurement devices, but the output signal digitization is not available in this patent application. Traditionally, analog signal digitization uses analog-to-digital conversion equipment to perform analog-to-digital conversion, but the measurement accuracy and measurement speed of the analog-to-digital conversion equipment cannot be achieved at the same time.

Summary of the invention

The technical problem to be solved by the present invention is that the existing broadband current measurement method cannot solve the problem that a single analog-to-digital conversion device cannot take into account both conversion accuracy and conversion rate.

The present invention solves the above technical problems by the following technical means: a broadband dynamic current signal high-speed measurement method based on optical principles, comprising the following steps:

Step 1, obtaining the analog voltage signal output by the optical current sensing unit at time t;

Step 2: Based on the analog voltage signal, low-pass analog filtering and band-pass analog filtering are performed respectively to obtain a low-frequency voltage signal and a high-frequency voltage signal output by the optical current sensing unit at time t;

Step 3: Under the triggering of the sampling clock, the low-frequency voltage signal is subjected to high-precision analog-to-digital conversion, and the high-frequency voltage signal is subjected to high-speed analog-to-digital conversion to obtain a low-frequency discrete voltage signal and a high-frequency discrete voltage signal;

Step 4: synthesizing a broadband current signal output by the optical current sensing unit according to the Fourier transform results of the low-frequency discrete voltage signal and the high-frequency discrete voltage signal, wherein the broadband current signal is a broadband analog current signal or a broadband discrete current signal;

Step 5: Discretize, quantize and encode the broadband current signal, and output message data.

The present invention performs frequency division processing on the current signal output by the optical current sensing unit, performs high-precision and low-speed analog-to-digital conversion on the low-frequency signal, and performs high-speed analog-to-digital conversion on the high-frequency signal, thereby achieving accurate and rapid measurement of wide-band dynamic current signals, solving the problem that a single analog-to-digital conversion device cannot take into account both conversion accuracy and conversion rate. Compared with traditional optical current transformers, the present invention has better time-frequency response characteristics for high-frequency current signals, can output more accurate primary current information, ensures the working reliability of metering, measurement, control and protection equipment, and has very good economic benefits.

Furthermore, the step 2 comprises:

The analog voltage signal U(t) is connected in parallel to output two voltage signals U ₁ (t) and U ₂ (t). The three signals satisfy the following relationship: U(t)=U ₁ (t)=U ₂ (t);

Perform low-pass filtering on the voltage signal U ₁ (t) to obtain the low-frequency voltage signal U _L (t) output by the optical current sensor unit at time t, and the cut-off frequency of the low-pass filter circuit is 500 Hz;

The voltage signal U ₂ (t) is band-pass filtered to obtain a high-frequency voltage signal U _H (t) output by the optical current sensor unit at time t. The cut-off frequency of the band-pass filter circuit is 500-3000 Hz.

Furthermore, the step three comprises:

The synchronous clock unit is used to output two second pulse signals F1 and F2 in parallel. The rising edge of F1 triggers the high-precision analog-to-digital conversion device to trigger sampling of the low-frequency voltage signal U _L (t). The rising edge of F2 triggers the high-speed analog-to-digital conversion device to trigger sampling of the high-frequency voltage signal U _H (t).

For the low-frequency voltage signal U _L (t), based on a 24-bit Σ-△ type high-precision analog-to-digital conversion device, at the next sampling clock of the rising edge of the second pulse signal F1, the low-frequency voltage signal U _L (t) is continuously and uniformly sampled to obtain the low-frequency discrete voltage signal U _L (n _SL ). The relationship between U _L (n _SL ) and U _L (t) is as follows:

_UL ( _nSL )＝ _UL (t+Δt+( _{nSL -} 1)/ _fSL ) _{1≤nSL≤NSL}

Wherein, Δt is the time difference between the rising edge of the second pulse signal F1 and the inherent sampling pulse of the 24-bit Σ-△ type high-precision analog-to-digital conversion device, _fSL is the sampling rate of the 24-bit Σ-△ type high-precision analog-to-digital conversion device; _nSL is the sampling point number of the low-frequency voltage signal, and _NSL is the total number of sampling points of the low-frequency voltage signal;

Based on the high-speed analog-to-digital conversion device, the high-frequency voltage signal U _H (t) is continuously and uniformly sampled under the triggering of the rising edge of the second pulse F2 to obtain the high-frequency discrete voltage signal U _H (n _SH ). The relationship between U _H (n _SH ) and _{U H (} t) is as follows:

U _H (n _SH ) = U _H (t + (n _SH -1) / f _SH ) 1 ≤ _{n SH} ≤ _{N SH}

Wherein, _fSH is the sampling rate of the high-speed analog-to-digital conversion device, _nSH is the sampling point number of the high-frequency voltage signal, and _NSH is the total number of sampling points of the high-frequency voltage signal.

Furthermore, the calculation process of the time difference Δt is:

The synchronous clock unit outputs two second pulse signals F1 and F2 in parallel and simultaneously outputs a high-frequency counting pulse signal Fp in parallel, and the frequency fp can be 50MHz;

The pulse-per-second signal F1, the sampling clock signal FL of the high-precision analog-to-digital conversion device, and the high-frequency counting pulse signal Fp are connected to the synchronous time compensation unit;

When the synchronous time compensation unit determines that the second pulse signal F1 is a rising edge, the high-frequency counting unit starts counting. Each time the high-frequency counting pulse signal Fp rises, the high-frequency counting unit counts by 1.

When the synchronous time compensation unit determines that the sampling clock signal FL of the high-precision analog-to-digital conversion device is at a rising edge, the high-frequency counting unit stops counting, and the count of the high-frequency counting unit is Nt at this time;

The time difference Δt is calculated according to the formula Δt=Nt/fp.

By performing high-precision low-speed analog-to-digital conversion on low-frequency signals and high-speed analog-to-digital conversion on high-frequency signals, accurate and fast measurement of broadband dynamic current signals is achieved. Generally, the number of sampling points _NL is 1024, the number of sampling points _NH is 4000, _fL is 10kHz, and _fH is 1MHz. By designing a synchronous time compensation unit, the time difference between the starting sampling moments of the high-precision low-speed analog-to-digital conversion device and the high-speed analog-to-digital conversion device is calculated, and the initial phases of the low-frequency voltage signal and the high-frequency voltage signal are synchronized in the time domain, so as to achieve accurate inversion of the measured broadband current signal.

Furthermore, the step 4 includes:

Based on the low-frequency discrete voltage signal U _L (n _SL ) and the high-frequency discrete voltage signal U _H (n _SH ), Fourier transform is performed to obtain the low-frequency discrete voltage signal U _L (n _SL ) and the high-frequency discrete voltage signal U _H (n _SH ) corresponding to the low-frequency discrete voltage signal U _L (t) and the high-frequency discrete voltage signal U _H (t), as shown below:

Where U ₀ (t) is the DC voltage signal output by the optical current sensor unit at time t, n _L is the harmonic order of the low-frequency voltage signal, and n _H is the harmonic order of the high-frequency voltage signal. is the peak value of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the peak value of the n _Hth high-frequency harmonic voltage output by the optical current sensor unit at time t, is the initial phase of n _Lth low-frequency harmonic voltage,/> is the actual initial phase of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the initial phase of the n _H subharmonic voltage output by the optical current sensing unit at time t; U _L (t) and U _H (t) here are obtained based on the Fourier transformation of the low-frequency discrete signal U _L (n _SL ) and the high-frequency discrete signal U _H (n _SH ), respectively, and the following formula is the Fourier transform expression. Fourier analysis is a signal processing method well known to those skilled in the art, so it is not described in detail in the present invention.

Based on the high-frequency voltage signal U _H (t), the stability of the measured current signal is judged. If the measured current signal is stable, it is recorded as A1. If the measured current signal is non-stationary, it is recorded as A2.

If the measured current signal is stable, at A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit is as shown in the following formula:

Where, K is the photoelectric detection coefficient of the optical current sensing unit, N is the number of optical fiber turns of the optical current sensing unit, and V is the Verdet constant of the optical device in the optical current sensing unit;

If the measured current signal is non-stationary, i.e., A2, the broadband discrete current signal I(n _SH ) output by the synthesized optical current sensing unit is as shown in the following formula:

I(n _SH )＝[U _L (1)+U _H (n _SH )]/(4K*N*V) 1≤n _SH ≤N _SH .

Furthermore, the process of determining the stability of the measured current signal is as follows:

Establish a time series {U ₀ (t-10), U ₀ (t-9), ..., U ₀ (t-1)} of the DC voltage component of the output signal of the optical current sensing unit, and calculate its expected value E(U ₀ (t));

Establish the time series of broadband voltage signal components output by the optical current sensing unit

Calculate the ratio of the broadband voltage signal component to the DC voltage component at the corresponding sampling moment and establish its time series And calculate their expected values respectively/> and its population standard deviation/>

The ratio of the broadband voltage signal component output by the optical current sensor unit at time t to the expected value of the DC component E(U ₀ (t)) is calculated and recorded as According to its value, determine whether the measured current signal is stable: if /> All meet If the measured current signal is a stable signal, it is recorded as A1; otherwise, the measured current signal is a non-stationary signal, which is recorded as A2.

In the above, the stability of the measured current signal is judged by the voltage signal output by the optical current sensing unit. When the measured current signal is stable, the synthesized wide-band analog current signal I(t) retains all the information of the measured current signal, thereby ensuring the measurement accuracy of the steady-state wide-band current signal. When the measured current signal is non-stationary, the synthesized wide-band discrete current signal I(n _H ) retains the first sampling value of the high-precision analog-to-digital conversion device and all the sampling values of the high-speed analog-to-digital conversion device, thereby ensuring the rapid measurement and response of the wide-band transient signal.

Furthermore, the step five includes:

If the measured current signal is stable, i.e., A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit at time t is discretized to obtain the broadband current discrete signal I(n), as follows:

I(n)＝I(t+(n-1)/f _I ) _1≤n≤NI

Where, f _I is the discrete frequency of the broadband current signal, f _I = 4kHz, and N _I is the number of discrete points of the broadband circuit signal within t seconds;

If the measured current signal is non-stationary, for example A2, the discrete signal of the broadband current is:

_I (n)＝[ _UL (1)+ _UH ( _nSH )]/(4K*N*V) 1≤n≤NI

Wherein, n＝n _SH ;

Quantize the discrete signal I(n) of the broadband current to obtain the corresponding result Δ(n);

Δ(n) is hexadecimal encoded and the message data is output according to the IEC60044-8 protocol.

The present invention also provides a broadband dynamic current signal high-speed measurement system based on optical principles, comprising:

An analog voltage signal acquisition module is used to acquire the analog voltage signal output by the optical current sensing unit at time t;

An analog signal filtering module, used to perform low-pass analog filtering and band-pass analog filtering based on the analog voltage signal, respectively, to obtain a low-frequency voltage signal and a high-frequency voltage signal output by the optical current sensing unit at time t;

An analog signal conversion module is used to perform high-precision analog-to-digital conversion on the low-frequency voltage signal and high-speed analog-to-digital conversion on the high-frequency voltage signal under the triggering of a sampling clock, so as to obtain a low-frequency discrete voltage signal and a high-frequency discrete voltage signal;

A signal processing module, used for synthesizing a broadband current signal output by the optical current sensing unit according to Fourier transform results of the low-frequency discrete voltage signal and the high-frequency discrete voltage signal, wherein the broadband current signal is a broadband analog current signal or a broadband discrete current signal;

The data encoding output module is used to discretize, quantize and encode the broadband current signal and output message data.

Furthermore, the analog signal filtering module is also used for:

The analog voltage signal U(t) is connected in parallel to output two voltage signals U ₁ (t) and U ₂ (t). The three signals satisfy the following relationship: U(t)=U ₁ (t)=U ₂ (t);

Perform low-pass filtering on the voltage signal U ₁ (t) to obtain the low-frequency voltage signal U _L (t) output by the optical current sensor unit at time t, and the cut-off frequency of the low-pass filter circuit is 500 Hz;

The voltage signal U ₂ (t) is band-pass filtered to obtain a high-frequency voltage signal U _H (t) output by the optical current sensing unit at time t. The cut-off frequency of the band-pass filter circuit is 500-3000 Hz.

Furthermore, the analog signal conversion module is also used for:

The synchronous clock unit is used to output two second pulse signals F1 and F2 in parallel. The rising edge of F1 triggers the high-precision analog-to-digital conversion device to trigger sampling of the low-frequency voltage signal U _L (t). The rising edge of F2 triggers the high-speed analog-to-digital conversion device to trigger sampling of the high-frequency voltage signal U _H (t).

For the low-frequency voltage signal U _L (t), based on a 24-bit Σ-△ type high-precision analog-to-digital conversion device, at the next sampling clock of the rising edge of the second pulse signal F1, the low-frequency voltage signal U _L (t) is continuously and uniformly sampled to obtain the low-frequency discrete voltage signal U _L (n _SL ). The relationship between U _L (n _SL ) and U _L (t) is as follows:

_UL ( _nSL )＝ _UL (t+Δt+( _{nSL -} 1)/ _fSL ) _{1≤nSL≤NSL}

Wherein, Δt is the time difference between the rising edge of the second pulse signal F1 and the inherent sampling pulse of the 24-bit Σ-△ type high-precision analog-to-digital conversion device, _fSL is the sampling rate of the 24-bit Σ-△ type high-precision analog-to-digital conversion device; _nSL is the sampling point number of the low-frequency voltage signal, and _NSL is the total number of sampling points of the low-frequency voltage signal;

Based on the high-speed analog-to-digital conversion device, the high-frequency voltage signal U _H (t) is continuously and uniformly sampled under the triggering of the rising edge of the second pulse F2 to obtain the high-frequency discrete voltage signal U _H (n _SH ). The relationship between U _H (n _SH ) and _{U H (} t) is as follows:

U _H (n _SH ) = U _H (t + (n _SH -1) / f _SH ) 1 ≤ _{n SH} ≤ _{N SH}

Wherein, _fSH is the sampling rate of the high-speed analog-to-digital conversion device, _nSH is the sampling point number of the high-frequency voltage signal, and _NSH is the total number of sampling points of the high-frequency voltage signal.

Furthermore, the calculation process of the time difference Δt is:

The synchronous clock unit outputs two second pulse signals F1 and F2 in parallel and simultaneously outputs a high-frequency counting pulse signal Fp in parallel, and its frequency fp can be 50MHz;

The pulse-per-second signal F1, the sampling clock signal FL of the high-precision analog-to-digital conversion device, and the high-frequency counting pulse signal Fp are connected to the synchronous time compensation unit;

When the synchronous time compensation unit determines that the second pulse signal F1 is a rising edge, the high-frequency counting unit starts counting. Each time the high-frequency counting pulse signal Fp rises, the high-frequency counting unit counts by 1.

When the synchronous time compensation unit determines that the sampling clock signal FL of the high-precision analog-to-digital conversion device is at a rising edge, the high-frequency counting unit stops counting, and the count of the high-frequency counting unit is Nt at this time;

The time difference Δt is calculated according to the formula Δt=Nt/fp.

Furthermore, the signal processing module is also used for:

Based on the low-frequency discrete voltage signal U _L (n _SL ) and the high-frequency discrete voltage signal U _H (n _SH ), Fourier transform is performed to calculate the low-frequency voltage signal U _L (t) and the high-frequency voltage signal U _H ( _t ) corresponding to the low-frequency discrete voltage signal U _L (n _SL ) and the high-frequency discrete voltage signal U _H (n SH ), respectively, as shown below:

Where U ₀ (t) is the DC voltage signal output by the optical current sensor unit at time t, n _L is the harmonic order of the low-frequency voltage signal, and n _H is the harmonic order of the high-frequency voltage signal. is the peak value of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the peak value of the n _Hth high-frequency harmonic voltage output by the optical current sensor unit at time t, is the initial phase of n _Lth low-frequency harmonic voltage,/> is the actual initial phase of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the initial phase of the n _H subharmonic voltage output by the optical current sensing unit at time t; U _L (t) and U _H (t) here are obtained based on the Fourier transformation of the low-frequency discrete signal U _L (n _SL ) and the high-frequency discrete signal U _H (n _SH ), respectively, and the following formula is the Fourier transform expression. Fourier analysis is a signal processing method well known to those skilled in the art, so it is not described in detail in the present invention.

Based on the high-frequency voltage signal U _H (t), the stability of the measured current signal is judged. If the measured current signal is stable, it is recorded as A1. If the measured current signal is non-stationary, it is recorded as A2.

If the measured current signal is stable, at A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit is as shown in the following formula:

Where, K is the photoelectric detection coefficient of the optical current sensing unit, N is the number of optical fiber turns of the optical current sensing unit, and V is the Verdet constant of the optical device in the optical current sensing unit;

If the measured current signal is non-stationary, i.e. A2, the broadband discrete current signal U(n _SH ) output by the synthesized optical current sensing unit is as shown in the following formula:

I(n _SH )＝[U _L (1)+U _H (n _SH )]/(4K*N*V) 1≤n _SH ≤N _SH .

Furthermore, the process of determining the stability of the measured current signal is as follows:

Establish a time series {U ₀ (t-10), U ₀ (t-9), ..., U ₀ (t-1)} of the DC voltage component of the output signal of the optical current sensing unit, and calculate its expected value E(U ₀ (t));

Establish the time series of broadband voltage signal components output by the optical current sensing unit

Calculate the ratio of the broadband voltage signal component to the DC voltage component at the corresponding sampling moment and establish its time series And calculate their expected values respectively/> and its population standard deviation/>

The ratio of the broadband voltage signal component output by the optical current sensor unit at time t to the expected value of the DC component E(U ₀ (t)) is calculated and recorded as According to its value, determine whether the measured current signal is stable: if /> All meet If the measured current signal is a stable signal, it is recorded as A1; otherwise, the measured current signal is a non-stationary signal, which is recorded as A2.

Furthermore, the data encoding output module is also used for:

If the measured current signal is stable, i.e., A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit at time t is discretized to obtain the broadband current discrete signal I(n), as follows:

I(n)＝I(t+(n-1)/f _I ) _1≤n≤NI

Where, f _I is the discrete frequency of the broadband current signal, f _I = 4kHz, and N _I is the number of discrete points of the broadband circuit signal within t seconds;

If the measured current signal is non-stationary, for example A2, the discrete signal of the broadband current is:

_I (n)＝[ _UL (1)+ _UH ( _nSH )]/(4K*N*V) 1≤n≤NI

Wherein, n＝n _SH ;

Quantize the discrete signal I(n) of the broadband current to obtain the corresponding result Δ(n);

Δ(n) is hexadecimal encoded and the message data is output according to the IEC60044-8 protocol.

The advantages of the present invention are:

(1) The present invention performs frequency division processing on the current signal output by the optical current sensing unit, performs high-precision and low-speed analog-to-digital conversion on the low-frequency signal, and performs high-speed analog-to-digital conversion on the high-frequency signal, thereby achieving accurate and rapid measurement of wide-band dynamic current signals, solving the problem that a single analog-to-digital conversion device cannot take into account both conversion accuracy and conversion rate. Compared with traditional optical current transformers, the present invention has better time-frequency response characteristics for high-frequency current signals, can output more accurate primary current information, ensure the working reliability of metering, measurement, control and protection equipment, and has very good economic benefits.

(2) The present invention processes the measurement signal output by the optical current sensing unit by filtering it in frequency bands, performs high-precision low-sampling-rate analog-to-digital conversion on the low-frequency signal, performs high-sampling-rate analog-to-digital conversion on the high-frequency signal, and selects a signal synthesis method based on the time-frequency domain characteristics of the two. This can achieve accurate measurement of the signal when the measured current is stable, and can quickly perceive the change process of the signal when the measured current is not stable, thus better adapting to the operation requirements of the new power system under the condition of a high proportion of new energy grid connection.

(3) The present invention designs a synchronization time compensation unit to calculate the time difference between the starting sampling moments of a high-precision low-speed analog-to-digital conversion device and a high-speed analog-to-digital conversion device, thereby achieving synchronization of the initial phases of a low-frequency voltage signal and a high-frequency voltage signal in the time domain, thereby achieving accurate inversion of the measured wide-band current signal.

(4) The present invention determines the stability of the measured current signal through the voltage signal output by the optical current sensing unit. When the measured current signal is stable, the synthesized wide-band analog current signal I(t) retains all the information of the measured current signal, thereby ensuring the measurement accuracy of the steady-state wide-band current signal. When the measured current signal is non-stationary, the synthesized wide-band discrete current signal I( _nH ) retains the first sampling value of the high-precision analog-to-digital conversion device and all the sampling values of the high-speed analog-to-digital conversion device, thereby ensuring the rapid measurement and response of the wide-band transient signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a method for high-speed measurement of broadband dynamic current signals based on optical principles disclosed in Embodiment 1 of the present invention;

FIG2 is a schematic structural diagram of time compensation in a broadband dynamic current signal high-speed measurement method based on optical principles disclosed in Example 1 of the present invention;

FIG3 is a schematic diagram of the structure of a broadband dynamic current signal high-speed measurement system based on optical principles disclosed in Example 2 of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Example 1

As shown in FIG1 , the high-speed measurement method for broadband dynamic current signals based on optical principles includes the following steps:

S1, obtaining an analog voltage signal output by the optical current sensing unit at time t; in this embodiment, this step is mainly based on the optical current sensing unit measuring the measured current signal and outputting a voltage signal U(t) proportional to the measured current signal;

S2. Based on the analog voltage signal, low-pass analog filtering and band-pass analog filtering are performed respectively to obtain a low-frequency voltage signal and a high-frequency voltage signal output by the optical current sensing unit at time t. The specific process is as follows:

S21, the analog voltage signal U(t) is connected in parallel to output two voltage signals U ₁ (t) and U ₂ (t), and the three signals satisfy the following relationship: U(t)=U ₁ (t)=U ₂ (t);

S22, performing low-pass filtering on the voltage signal U ₁ (t) to obtain the low-frequency voltage signal U _L (t) output by the optical current sensing unit at time t, wherein the cut-off frequency of the low-pass filtering circuit is 500 Hz;

S23, band-pass filtering the voltage signal _U2 (t) to obtain the high-frequency voltage signal _UH (t) output by the optical current sensing unit at time t, and the cut-off frequency of the band-pass filter circuit is 500-3000 Hz. It should be noted that both the low-frequency voltage signal _UL (t) and the high-frequency voltage signal _UH (t) are in an unsolved state, which is equivalent to an unknown expression symbol and needs to be calculated in the subsequent Fourier transform process.

S3. Under the triggering of the sampling clock, the low-frequency voltage signal is subjected to high-precision analog-to-digital conversion, and the high-frequency voltage signal is subjected to high-speed analog-to-digital conversion to obtain a low-frequency discrete voltage signal and a high-frequency discrete voltage signal. The specific process is as follows:

S31, using the synchronous clock unit to output two second pulse signals F1 and F2 in parallel, the rising edge of F1 triggers the high-precision analog-to-digital conversion device to trigger sampling of the low-frequency voltage signal U _L (t), and the rising edge of F2 triggers the high-speed analog-to-digital conversion device to trigger sampling of the high-frequency voltage signal U _H (t);

S32. Based on a 24-bit Σ-△ type high-precision analog-to-digital conversion device, the low-frequency voltage signal U _L (t) is continuously and uniformly sampled at the next sampling clock of the rising edge of the pulse-per-second signal F1 to obtain a low-frequency discrete voltage signal U _L (n _SL ). The relationship between U _L (n _SL ) and _{U L (} t) is as follows:

_UL ( _nSL )＝ _UL (t+Δt+( _{nSL -} 1)/ _fSL ) _{1≤nSL≤NSL}

Wherein, Δt is the time difference between the rising edge of the second pulse signal F1 and the inherent sampling pulse of the 24-bit Σ-△ type high-precision analog-to-digital conversion device, _fSL is the sampling rate of the 24-bit Σ-△ type high-precision analog-to-digital conversion device; _nSL is the sampling point number of the low-frequency voltage signal, and _NSL is the total number of sampling points of the low-frequency voltage signal;

S33. Based on the high-speed analog-to-digital conversion device, the high-frequency voltage signal U _H (t) is continuously and uniformly sampled under the triggering of the rising edge of the second pulse F2 to obtain a high-frequency discrete voltage signal U _H (n _SH ). The relationship between U _H (n _SH ) and _{U H (} t) is as follows:

U _H (n _SH ) = U _H (t + (n _SH -1) / f _SH ) 1 ≤ _{n SH} ≤ _{N SH}

Wherein, _fSH is the sampling rate of the high-speed analog-to-digital conversion device, _nSH is the sampling point number of the high-frequency voltage signal, and _NSH is the total number of sampling points of the high-frequency voltage signal.

In this embodiment, as a further improvement, as shown in FIG2 , the calculation process of the time difference Δt between the rising edge of the second pulse signal F1 and the inherent sampling pulse of the 24-bit Σ-Δ type high-precision analog-to-digital conversion device in step S32 is:

S321, the synchronous clock unit outputs two second pulse signals F1 and F2 in parallel and simultaneously outputs a high-frequency counting pulse signal Fp in parallel, and the frequency fp can be 50MHz;

S322, connecting the pulse-per-second signal F1, the sampling clock signal FL of the high-precision analog-to-digital conversion device, and the high-frequency counting pulse signal Fp to a synchronous time compensation unit;

S323, when the synchronous time compensation unit determines that the second pulse signal F1 is a rising edge, the high-frequency counting unit is started to count, and the high-frequency counting unit counts by 1 for each rising edge of the high-frequency counting pulse signal Fp;

S324, when the synchronous time compensation unit determines that the sampling clock signal FL of the high-precision analog-to-digital conversion device is at a rising edge, the high-frequency counting unit stops counting, and the count of the high-frequency counting unit is Nt at this time;

S325 , calculating the time difference Δt that needs to be compensated by the synchronous high-precision analog-to-digital conversion device according to the formula Δt=Nt/fp.

By performing high-precision low-speed analog-to-digital conversion on low-frequency signals and high-speed analog-to-digital conversion on high-frequency signals, accurate and fast measurement of broadband dynamic current signals is achieved. Generally, the number of sampling points _NL is 1024, the number of sampling points _NH is 4000, _fL is 10kHz, and _fH is 1MHz. By designing a synchronous time compensation unit, the time difference between the starting sampling moments of the high-precision low-speed analog-to-digital conversion device and the high-speed analog-to-digital conversion device is calculated, and the initial phases of the low-frequency voltage signal and the high-frequency voltage signal are synchronized in the time domain, so as to achieve accurate inversion of the measured broadband current signal.

S4. According to the Fourier transform results of the low-frequency discrete voltage signal and the high-frequency discrete voltage signal, synthesize the broadband current signal output by the optical current sensing unit, where the broadband current signal is a broadband analog current signal or a broadband discrete current signal. The specific process is as follows:

S41, performing Fourier transform based on the low-frequency discrete voltage signal _UL ( _nSL ) and the high-frequency discrete voltage signal _UH ( _nSH ), respectively calculating the low-frequency voltage signal _UL (t) and the high-frequency voltage signal _UH (t) corresponding to the low-frequency discrete voltage signal _UL ( _nSL ) and the high-frequency discrete voltage signal _UH ( _nSH ), as shown below:

Where U ₀ (t) is the DC voltage signal output by the optical current sensor unit at time t, n _L is the harmonic order of the low-frequency voltage signal, and n _H is the harmonic order of the high-frequency voltage signal. is the peak value of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the peak value of the n _Hth high-frequency harmonic voltage output by the optical current sensor unit at time t, is the initial phase of n _Lth low-frequency harmonic voltage,/> is the actual initial phase of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the initial phase of the n _H subharmonic voltage output by the optical current sensing unit at time t; U _L (t) and U _H (t) here are obtained based on the Fourier transformation of the low-frequency discrete signal U _L (n _SL ) and the high-frequency discrete signal U _H (n _SH ), respectively, and the following formula is the Fourier transform expression. Fourier analysis is a signal processing method well known to those skilled in the art, so it is not described in detail in this embodiment.

S42, judging the stability of the measured current signal based on the high-frequency voltage signal U _H (t), if the measured current signal is stable, it is recorded as A1, if the measured current signal is non-stationary, it is recorded as A2;

S43, based on the stability judgment of the measured current signal, select different synthesis modes of the measured current signal, as follows:

If the measured current signal is stable, at A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit is as shown in the following formula:

Where, K is the photoelectric detection coefficient of the optical current sensing unit, N is the number of optical fiber turns of the optical current sensing unit, and V is the Verdet constant of the optical device in the optical current sensing unit;

If the measured current signal is non-stationary, i.e. A2, the broadband discrete current signal I(n _SH ) output by the synthesized optical current sensing unit is as shown in the following formula:

I(n _SH )＝[ _UL (1)+ _UH (n _SH )]/(4K*N*V) 1≤n _SH ≤N _SH . In this embodiment, as a further improvement, the process of determining the stability of the measured current signal in step S42 is:

S421, establishing a time series {U ₀ (t-10), U ₀ (t-9), ..., U ₀ (t-1)} of the DC voltage component of the output signal of the optical current sensing unit, and calculating its expected value E(U ₀ (t));

S422: Establishing a time series of broadband voltage signal components output by the optical current sensing unit

S423, respectively calculate the ratio of the broadband voltage signal component to the DC voltage component at the corresponding sampling time, and establish its time series And calculate their expected values respectively/> and its population standard deviation/>

S424, respectively calculate the ratio of the broadband voltage signal component output by the optical current sensor unit at time t to the expected value of the DC component E(U ₀ (t)), which is recorded as According to its value, determine whether the measured current signal is stable: if /> All meet/> If the measured current signal is a stable signal, it is recorded as A1; otherwise, the measured current signal is a non-stationary signal, which is recorded as A2.

In the above, the stability of the measured current signal is judged by the voltage signal output by the optical current sensing unit. When the measured current signal is stable, the synthesized wide-band analog current signal I(t) retains all the information of the measured current signal, thereby ensuring the measurement accuracy of the steady-state wide-band current signal. When the measured current signal is non-stationary, the synthesized wide-band discrete current signal I(n _H ) retains the first sampling value of the high-precision analog-to-digital conversion device and all the sampling values of the high-speed analog-to-digital conversion device, thereby ensuring the rapid measurement and response to the wide-band transient signal.

S5. Discretize, quantize and encode the broadband current signal and output message data. The specific process is as follows:

S51, if the measured current signal is stable, i.e., A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit at time t is discretized to obtain a broadband current discrete signal I(n), as follows:

I(n)＝I(t+(n-1)/f _I ) _1≤n≤NI

Where, f _I is the discrete frequency of the broadband current signal, f _I = 4kHz, N _I is the number of discrete points of the broadband circuit signal within t seconds, N _I = 4000;

If the measured current signal is non-stationary, for example A2, the discrete signal of the broadband current is:

_I (n)＝[ _UL (1)+ _UH ( _nSH )]/(4K*N*V) 1≤n≤NI

Wherein, n＝n _SH ;

S52, quantizing the discrete signal I(n) of the broadband current to obtain a corresponding result Δ(n);

S53, encode Δ(n) in hexadecimal and output message data according to the IEC60044-8 protocol.

Through the above technical scheme, the present invention adopts a broadband current measurement scheme of a dual analog-to-digital conversion device, uses a high-precision analog-to-digital conversion device to accurately measure low-frequency signals, and uses a fast analog-to-digital conversion device to quickly track high-frequency signals. Compared with the traditional analog-to-digital conversion scheme, the present invention can take into account both the measurement accuracy and measurement speed of broadband current signals. At the same time, in order to solve the problem that high-precision analog-to-digital conversion equipment and high-speed analog-to-digital conversion equipment cannot be strictly sampled synchronously, a time difference compensation method is further invented to ensure the synchronization of the measurement phase of low-frequency current signals and high-frequency current signals.

Example 2

As shown in FIG3 , based on Example 1, Example 2 of the present invention further provides a broadband dynamic current signal high-speed measurement system based on optical principles, including:

An analog voltage signal acquisition module is used to acquire the analog voltage signal output by the optical current sensing unit at time t;

An analog signal filtering module, used to perform low-pass analog filtering and band-pass analog filtering based on the analog voltage signal, respectively, to obtain a low-frequency voltage signal and a high-frequency voltage signal output by the optical current sensing unit at time t;

An analog signal conversion module is used to perform high-precision analog-to-digital conversion on the low-frequency voltage signal and high-speed analog-to-digital conversion on the high-frequency voltage signal under the triggering of a sampling clock, so as to obtain a low-frequency discrete voltage signal and a high-frequency discrete voltage signal;

A signal processing module, used for synthesizing a broadband current signal output by the optical current sensing unit according to Fourier transform results of the low-frequency discrete voltage signal and the high-frequency discrete voltage signal, wherein the broadband current signal is a broadband analog current signal or a broadband discrete current signal;

The data encoding output module is used to discretize, quantize and encode the broadband current signal and output message data.

Specifically, the analog signal filtering module is also used for:

The analog voltage signal U(t) is connected in parallel to output two voltage signals U ₁ (t) and U ₂ (t). The three signals satisfy the following relationship: U(t)=U ₁ (t)=U ₂ (t);

Perform low-pass filtering on the voltage signal U ₁ (t) to obtain the low-frequency voltage signal U _L (t) output by the optical current sensor unit at time t, and the cut-off frequency of the low-pass filter circuit is 500 Hz;

The voltage signal U ₂ (t) is band-pass filtered to obtain a high-frequency voltage signal U _H (t) output by the optical current sensing unit at time t. The cut-off frequency of the band-pass filter circuit is 500-3000 Hz.

Specifically, the analog signal conversion module is also used for:

The synchronous clock unit is used to output two second pulse signals F1 and F2 in parallel. The rising edge of F1 triggers the high-precision analog-to-digital conversion device to trigger sampling of the low-frequency voltage signal U _L (t). The rising edge of F2 triggers the high-speed analog-to-digital conversion device to trigger sampling of the high-frequency voltage signal U _H (t).

For the low-frequency voltage signal U _L (t), based on a 24-bit Σ-△ type high-precision analog-to-digital conversion device, at the next sampling clock of the rising edge of the second pulse signal F1, the low-frequency voltage signal U _L (t) is continuously and uniformly sampled to obtain the low-frequency discrete voltage signal U _L (n _SL ). The relationship between U _L (n _SL ) and U _L (t) is as follows:

_UL ( _nSL )＝ _UL (t+Δt+( _{nSL -} 1)/ _fSL ) _{1≤nSL≤NSL}

Wherein, Δt is the time difference between the rising edge of the second pulse signal F1 and the inherent sampling pulse of the 24-bit Σ-△ type high-precision analog-to-digital conversion device, _fSL is the sampling rate of the 24-bit Σ-△ type high-precision analog-to-digital conversion device; _nSL is the sampling point number of the low-frequency voltage signal, and _NSL is the total number of sampling points of the low-frequency voltage signal;

Based on the high-speed analog-to-digital conversion device, the high-frequency voltage signal U _H (t) is continuously and uniformly sampled under the triggering of the rising edge of the second pulse F2 to obtain the high-frequency discrete voltage signal I _H (n _SH ). The relationship between U _H (n _SH ) and _{U H (} t) is as follows:

U _H (n _SH ) = U _H (t + (n _SH -1) / f _SH ) 1 ≤ _{n SH} ≤ _{N SH}

Wherein, _fSH is the sampling rate of the high-speed analog-to-digital conversion device, _nSH is the sampling point number of the high-frequency voltage signal, and _NSH is the total number of sampling points of the high-frequency voltage signal.

More specifically, the calculation process of the time difference Δt is:

The synchronous clock unit outputs two second pulse signals F1 and F2 in parallel and simultaneously outputs a high-frequency counting pulse signal Fp in parallel, and its frequency fp can be 50MHz;

The pulse-per-second signal F1, the sampling clock signal FL of the high-precision analog-to-digital conversion device, and the high-frequency counting pulse signal Fp are connected to the synchronous time compensation unit;

When the synchronous time compensation unit determines that the second pulse signal F1 is a rising edge, the high-frequency counting unit starts counting. Each time the high-frequency counting pulse signal Fp rises, the high-frequency counting unit counts by 1.

When the synchronous time compensation unit determines that the sampling clock signal FL of the high-precision analog-to-digital conversion device is at a rising edge, the high-frequency counting unit stops counting, and the count of the high-frequency counting unit is Nt at this time;

The time difference Δt is calculated according to the formula Δt=Nt/fp.

Specifically, the signal processing module is further used for:

Based on the low-frequency discrete voltage signal _UL ( _nSL ) and the high-frequency discrete voltage signal _UH ( _nSH ), Fourier transform is performed to calculate the low-frequency voltage signal _UL (t) and the high-frequency voltage signal _UH (t) corresponding to the low-frequency discrete voltage signal _UL ( _nSL ) and the high-frequency discrete voltage signal _UH ( _nSH ), as shown below:

Where U ₀ (t) is the DC voltage signal output by the optical current sensor unit at time t, n _L is the harmonic order of the low-frequency voltage signal, and n _H is the harmonic order of the high-frequency voltage signal. is the peak value of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the peak value of the n _Hth high-frequency harmonic voltage output by the optical current sensor unit at time t, is the initial phase of n _Lth low-frequency harmonic voltage,/> is the actual initial phase of the n _Lth low-frequency harmonic voltage output by the optical current sensing unit at time t, /> is the initial phase of the n _H subharmonic voltage output by the optical current sensing unit at time t; U _L (t) and U _H (t) here are obtained based on the Fourier transformation of the low-frequency discrete signal U _L (n _SL ) and the high-frequency discrete signal U _H (n _SH ), respectively, and the following formula is the Fourier transform expression. Fourier analysis is a signal processing method well known to those skilled in the art, so it is not described in detail in this embodiment.

Based on the high-frequency voltage signal U _H (t), the stability of the measured current signal is judged. If the measured current signal is stable, it is recorded as A1. If the measured current signal is non-stationary, it is recorded as A2.

If the measured current signal is stable, at A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit is as shown in the following formula:

Where, K is the photoelectric detection coefficient of the optical current sensing unit, N is the number of optical fiber turns of the optical current sensing unit, and V is the Verdet constant of the optical device in the optical current sensing unit;

If the measured current signal is non-stationary, i.e., A2, the broadband discrete current signal I(n _SH ) output by the synthesized optical current sensing unit is as shown in the following formula:

I(n _SH )＝[ _UL (1)+ _UH (n _SH )]/(4K*N*V) 1≤n _h ≤N _h .

More specifically, the process of determining the stability of the measured current signal is as follows:

Establish a time series {U ₀ (t-10), U ₀ (t-9), ..., U ₀ (t-1)} of the DC voltage component of the output signal of the optical current sensing unit, and calculate its expected value E(U ₀ (t));

Establish the time series of broadband voltage signal components output by the optical current sensing unit

Calculate the ratio of the broadband voltage signal component to the DC voltage component at the corresponding sampling moment and establish its time series And calculate their expected values respectively/> and its population standard deviation/>

The ratio of the broadband voltage signal component output by the optical current sensor unit at time t to the expected value of the DC component E(N ₀ (t)) is calculated and recorded as According to its value, determine whether the measured current signal is stable: if /> All meet Then the measured current signal is a steady signal, recorded as A1; otherwise, the measured current signal is a non-steady signal, recorded as A2.

More specifically, the data encoding output module is also used to:

If the measured current signal is stable, i.e., A1, the broadband analog current signal I(t) output by the synthesized optical current sensing unit at time t is discretized to obtain the broadband current discrete signal I(n), as follows:

I(n)＝I(t+(n-1)/f _I ) _1≤n≤NI

Where, fI _I is the discrete frequency of the broadband current signal, fI _I = 4kHz, N _I is the number of discrete points of the broadband circuit signal within t seconds;

If the measured current signal is non-stationary, for example A2, the discrete signal of the broadband current is:

_I (n)＝[ _UL (1)+ _UH ( _nSH )]/(4K*N*V) 1≤n≤NI

Wherein, n＝n _SH ;

Quantize the discrete signal I(n) of the broadband current to obtain the corresponding result Δ(n);

Δ(n) is hexadecimal encoded and the message data is output according to the IEC60044-8 protocol.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. The broadband dynamic current signal high-speed measurement method based on the optical principle is characterized by comprising the following steps of:

Step one, obtaining an analog voltage signal output by an optical current sensing unit at the moment t;

Step two, respectively performing low-pass analog filtering and band-pass analog filtering based on the analog voltage signals to obtain a low-frequency voltage signal and a high-frequency voltage signal which are output by the optical current sensing unit at the moment t;

step three, under the triggering of a sampling clock, performing high-precision analog-to-digital conversion on the low-frequency voltage signal, and performing high-speed analog-to-digital conversion on the high-frequency voltage signal to obtain a low-frequency discrete voltage signal and a high-frequency discrete voltage signal;

Synthesizing a broadband current signal output by the optical current sensing unit according to Fourier transform results of the low-frequency discrete voltage signal and the high-frequency discrete voltage signal, wherein the broadband current signal is a broadband analog current signal or a broadband discrete current signal;

And fifthly, dispersing, quantizing and encoding the broadband current signal to output message data.

2. The method for high-speed measurement of broadband dynamic current signals based on optical principles according to claim 1, wherein said step two comprises:

The analog voltage signal U (t) is connected in parallel to output two paths of voltage signals U ₁(t)、U₂ (t), and the three signals meet the following relation: u (t) =u ₁(t)＝U₂ (t);

Carrying out low-pass filtering on the voltage signal U ₁ (t) to obtain a low-frequency voltage signal U _L (t) output by the optical current sensing unit at the moment t, wherein the cut-off frequency of the low-pass filtering circuit is 500Hz;

And carrying out band-pass filtering on the voltage signal U ₂ (t) to obtain a high-frequency voltage signal U _H (t) output by the optical current sensing unit at the moment t, wherein the cut-off frequency of the band-pass filtering circuit is 500-3000 Hz.

3. The method for high-speed measurement of broadband dynamic current signals based on optical principles according to claim 1, wherein said step three comprises:

The synchronous clock unit is utilized to output two paths of second pulse signals F1 and F2 in parallel, the high-precision analog-to-digital conversion device is triggered and sampled when the F1 rises, the low-frequency voltage signal U _L (t) is triggered and sampled when the F2 rises, and the high-speed analog-to-digital conversion device is triggered and sampled when the F2 rises;

For the low-frequency voltage signal U _L (t), based on the 24-bit sigma-delta type high-precision analog-to-digital conversion device, at the next sampling clock of the rising edge of the second pulse signal F1, the low-frequency voltage signal U _L (t) is continuously and uniformly sampled, and the relationship between the low-frequency discrete voltage signals U _L(n_SL),U_L(n_SL) and U _L (t) is obtained as follows:

U_L(n_SL)＝U_L(t+Δt+(n_SL-1)/f_SL)1≤n_SL≤N_SL

Wherein Δt is the time difference between the rising edge of the second pulse signal F1 and the inherent sampling pulse of the 24-bit sigma-delta type high-precision analog-to-digital conversion device, and F _SL is the sampling rate of the 24-bit sigma-delta type high-precision analog-to-digital conversion device; n _SL is the number of sampling points of the low-frequency voltage signal, and N _SL is the total number of sampling points of the low-frequency voltage signal;

Based on the high-speed analog-digital conversion device, the high-frequency voltage signal U _H (t) is continuously and uniformly sampled under the trigger of the rising edge of the second pulse F2, and the relationship between the high-frequency discrete voltage signal U _H(n_SH),U_H(n_SH) and the high-frequency discrete voltage signal U _H (t) is obtained as follows:

U_H(n_SH)＝U_H(t+(n_SH-1)/f_SH)1≤n_SH≤N_SH

Where f _SH is the sampling rate of the high-speed analog-to-digital conversion device, N _SH is the sampling point number of the high-frequency voltage signal, and N _SH is the total sampling point number of the high-frequency voltage signal.

4. The method for high-speed measurement of broadband dynamic current signals based on optical principles according to claim 3, wherein the time difference Δt is calculated by:

The synchronous clock unit outputs two paths of second pulse signals F1 and F2 in parallel and simultaneously outputs a high-frequency counting pulse signal Fp in parallel, and the frequency Fp of the high-frequency counting pulse signal Fp is 50MHz;

the second pulse signal F1, a sampling clock signal FL of the high-precision analog-to-digital conversion device and the high-frequency counting pulse signal Fp are connected into a synchronous time compensation unit;

When the synchronous time compensation unit judges that the second pulse signal F1 is a rising edge, the high-frequency counting unit is started to count, and the high-frequency counting unit counts up 1 after every rising edge of the high-frequency counting pulse signal Fp;

When the synchronous time compensation unit judges that the sampling clock signal FL of the high-precision analog-to-digital conversion device is a rising edge, stopping counting by the high-frequency counting unit, wherein the counting of the high-frequency counting unit is Nt;

The time difference Δt is calculated according to the formula Δt=nt/fp.

5. The method for high-speed measurement of broadband dynamic current signals based on optical principles according to claim 1, wherein said step four comprises:

Based on the low frequency discrete voltage signal U _L(n_SL) and the high frequency discrete voltage signal U _H(n_SH), a fourier transform is performed to calculate a low frequency voltage signal U _L (t) and a high frequency voltage signal U _H (t) respectively corresponding to the low frequency discrete voltage signal U _L(n_SL) and the high frequency discrete voltage signal U _H(n_SH), respectively, as follows:

wherein U ₀ (t) is a direct current voltage signal output by the optical current sensing unit at the moment t, n _L is the harmonic frequency of the low-frequency voltage signal, n _H is the harmonic frequency of the high-frequency voltage signal, For the peak value of the n _L times low-frequency harmonic voltage output by the optical current sensing unit at the time t,/>For the peak value of the n _H times high-frequency harmonic voltage output by the optical current sensing unit at the time t,/>For the initial phase of the n _L times low-frequency harmonic voltage,/>For the actual initial phase of the n _L times low-frequency harmonic voltage output by the optical current sensing unit at the time t,/>The initial phase of the n _H th harmonic voltage output by the optical current sensing unit at the time t;

Based on the high-frequency voltage signal U _H (t), judging the stability of the detected current signal, if the detected current signal is stable, marking as A1, and if the detected current signal is non-stable, marking as A2;

If the measured current signal is stable and is A1, synthesizing a broadband analog current signal I (t) output by the optical current sensing unit, wherein the broadband analog current signal I (t) is shown as the following formula:

Wherein K is the photoelectric detection coefficient of the optical current sensing unit, N is the number of optical fiber turns of the optical current sensing unit, and V is the Wilde constant of an optical device in the optical current sensing unit;

if the measured current signal is not stable and is A2, synthesizing a broadband discrete current signal I (n _SH) output by the optical current sensing unit, wherein the broadband discrete current signal I is represented by the following formula:

I(n_SH)＝[U_L(1)+U_H(n_SH)]/(4K*N*V)1≤n_SH≤N_SH。

6. the method for measuring broadband dynamic current signals at high speed based on optical principle according to claim 5, wherein the process of determining the stability of the measured current signals is as follows:

Establishing a time sequence { U ₀(t-10)、U₀(t-9)、...、U₀ (t-1) } of direct current voltage components of the output signals of the optical current sensing unit, and calculating an expected value E (U ₀ (t));

Establishing a time sequence of broadband voltage signal components output by the optical current sensing unit

Respectively calculating the ratio of broadband voltage signal component to DC voltage component at corresponding sampling time, and establishing time sequenceAnd calculates the expected value/>, respectivelyAnd its total standard deviation/>

Calculating the ratio of the broadband voltage signal component and the expected value E (U ₀ (t)) of the direct current component output by the optical current sensing unit at the time t respectively, and recording asJudging whether the detected current signal is stable or not according to the value of the current signal: if/>All satisfyThe measured current signal is a stable signal and is marked as A1; otherwise, the measured current signal is a non-stationary signal, denoted as A2.

7. The method for high-speed measurement of broadband dynamic current signals based on optical principles according to claim 5, wherein said step five comprises:

If the detected current signal is stable and is A1, the broadband analog current signal I (t) output by the optical current sensing unit synthesized at the moment t is discretized to obtain a discrete signal I (n) of broadband current, which is specifically as follows:

I(n)＝I(t+(n-1)/f_I)1≤n≤N_I

Wherein, f _I is the discrete frequency of the broadband current signal, and f _I＝4kHz,N_I is the discrete point number of the broadband circuit signal within t seconds;

if the measured current signal is not stable, A2 is the signal of wideband current:

I(n)＝[U_L(1)+U_H(n_SH)]/(4K*N*V)1≤n≤N_I

Wherein n=n _H;

quantifying a discrete signal I (n) of the broadband current to obtain a corresponding result delta (n);

hexadecimal encoding is carried out on delta (n), and message data is output according to IEC60044-8 protocol.

8. The broadband dynamic current signal high-speed measurement system based on the optical principle is characterized by comprising:

The analog voltage signal acquisition module is used for acquiring an analog voltage signal output by the optical current sensing unit at the moment t;

The analog signal filtering module is used for respectively carrying out low-pass analog filtering and band-pass analog filtering based on the analog voltage signals to obtain a low-frequency voltage signal and a high-frequency voltage signal which are output by the optical current sensing unit at the moment t;

the analog signal conversion module is used for carrying out high-precision analog-to-digital conversion on the low-frequency voltage signal under the triggering of the sampling clock and carrying out high-speed analog-to-digital conversion on the high-frequency voltage signal to obtain a low-frequency discrete voltage signal and a high-frequency discrete voltage signal;

the signal processing module is used for synthesizing a broadband current signal output by the optical current sensing unit according to the Fourier transform results of the low-frequency discrete voltage signal and the high-frequency discrete voltage signal, wherein the broadband current signal is a broadband analog current signal or a broadband discrete current signal;

and the data coding output module is used for carrying out dispersion, quantization and coding on the broadband current signal and outputting message data.

9. The broadband dynamic current signal high-speed measurement system based on the optical principle according to claim 8, wherein the analog signal filtering module is further configured to:

The analog voltage signal U (t) is connected in parallel to output two paths of voltage signals U ₁(t)、U₂ (t), and the three signals meet the following relation: u (t) =u ₁(t)＝U₂ (t);

Carrying out low-pass filtering on the voltage signal U ₁ (t) to obtain a low-frequency voltage signal U _L (t) output by the optical current sensing unit at the moment t, wherein the cut-off frequency of the low-pass filtering circuit is 500Hz;

And carrying out band-pass filtering on the voltage signal U ₂ (t) to obtain a high-frequency voltage signal U _H (t) output by the optical current sensing unit at the moment t, wherein the cut-off frequency of the band-pass filtering circuit is 500-3000 Hz.

10. The broadband dynamic current signal high-speed measurement system based on the optical principle according to claim 8, wherein the analog signal conversion module is further configured to:

The synchronous clock unit is utilized to output two paths of second pulse signals F1 and F2 in parallel, the high-precision analog-to-digital conversion device is triggered and sampled when the F1 rises, the low-frequency voltage signal U _L (t) is triggered and sampled when the F2 rises, and the high-speed analog-to-digital conversion device is triggered and sampled when the F2 rises;

For the low-frequency voltage signal U _L (t), based on the 24-bit sigma-delta type high-precision analog-to-digital conversion device, at the next sampling clock of the rising edge of the second pulse signal F1, the low-frequency voltage signal U _L (t) is continuously and uniformly sampled, and the relationship between the low-frequency discrete voltage signals U _L(n_SL),U_L(n_SL) and U _L (t) is obtained as follows:

U_L(n_SL)＝U_L(t+Δt+(n_SL-1)/f_SL)1≤n_SL≤N_SL

Wherein Δt is the time difference between the rising edge of the second pulse signal F1 and the inherent sampling pulse of the 24-bit sigma-delta type high-precision analog-to-digital conversion device, and F _SL is the sampling rate of the 24-bit sigma-delta type high-precision analog-to-digital conversion device; n _SL is the number of sampling points of the low-frequency voltage signal, and N _SL is the total number of sampling points of the low-frequency voltage signal;

Based on the high-speed analog-digital conversion device, the high-frequency voltage signal U _H (t) is continuously and uniformly sampled under the trigger of the rising edge of the second pulse F2, and the relationship between the high-frequency discrete voltage signal U _H(n_SH),U_H(n_SH) and the high-frequency discrete voltage signal U _H (t) is obtained as follows:

U_H(n_SH)＝U_H(t+(n_SH-1)/f_SH)1≤n_SH≤N_SH

Where f _SH is the sampling rate of the high-speed analog-to-digital conversion device, N _SH is the sampling point number of the high-frequency voltage signal, and N _SH is the total sampling point number of the high-frequency voltage signal.