Phase-locked loop control method, device and equipment for fiber-optic current transformer and medium

Abstract

This invention relates to the field of fiber optic sensing technology, and more particularly to a phase-locked loop control method, apparatus, equipment, and medium for fiber optic current transformers. The method includes: forming an interference optical path signal after modulation by an electrical signal; converting the interference optical path signal into a sensing electrical signal and sending it to an analog-to-digital converter for digital sampling; and... m one modulation period T The sensor's electrical signals are processed, and... mT The sampled values ​​within a given time period are demodulated to obtain the modulation depth error and feedback phase error; a sine wave is generated based on the modulation depth error; and... N one modulation period T Feedback phase error processing generates a sawtooth wave, in which N=nm , n The signal is a positive integer; the generated sine wave and sawtooth wave are superimposed and provided to the digital-to-analog converter to form a modulation signal; the digital-to-analog converter converts the modulation signal into an electrical signal to realize closed-loop control of the fiber optic current transformer. This invention improves the measurement accuracy and dynamic range of the fiber optic current transformer while reducing product costs.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing technology, and in particular to a phase-locked loop control method, device, equipment, and medium for fiber optic current transformers. Background Technology

[0002] Fiber optic current transformers are optical sensors that employ an all-fiber optical path structure, where the optical fiber serves as both the light transmission medium and the sensing element. They possess advantages such as insulation, simple structure, high measurement accuracy, fast response speed, and strong resistance to electromagnetic interference, and have been widely used in the fields of power, metallurgy, and nuclear physics.

[0003] The principle of the fiber optic current transformer is as follows: the light emitted from the light source is polarized into linearly polarized light by a polarizer, and enters the fast and slow axes of the polarization-maintaining fiber through the 45° fiber melting point. The two orthogonal linearly polarized beams are modulated by a phase modulator and then propagated along the polarization-maintaining delay fiber. They are then converted into two circularly polarized beams with orthogonal rotation by a quarter-wave plate. Under the action of the measured current, a Faraday phase shift is generated between the two circularly polarized beams. After passing through the reflector at the end of the sensitive fiber, they return along the original path, and the current phase difference is doubled. After returning along the original optical path again, the orthogonal linearly polarized beams are finally detected by the polarizer and interference occurs.

[0004] Depending on the signal detection method, fiber optic current transformers can be implemented using either open-loop or closed-loop schemes. Closed-loop fiber optic current transformers typically use a superposition of square and stepped waves as modulation signals. The square wave is used for bias modulation, and the stepped wave is used for feedback modulation, effectively improving the measurement accuracy and dynamic range of the transformer system. However, this approach places higher demands on the selection of transformer components and the modulation and demodulation bandwidth, resulting in higher costs.

[0005] Open-loop fiber optic current transformers generally use sine waves as modulation signals. The working principle is simple and easy to implement. Sine wave modulation signals do not have high requirements for operating bandwidth and the equipment cost is low. However, currently only open-loop demodulation schemes are available. It is necessary to calculate the arctangent function, resulting in low sensitivity and small dynamic range. It can only be used in situations where the requirements for measurement accuracy and measurement range are low.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the general background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] This invention provides a phase-locked loop control method, device, equipment, and medium for fiber optic current transformers, thereby effectively solving the problems in the background art.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a phase-locked loop control method for fiber optic current transformers, comprising the following steps:

[0009] The input optical signal entering the modulator in the fiber optic current transformer is modulated by an electrical signal to form an interference optical path signal. The interference optical path signal is then converted into a sensing electrical signal and sent to an analog-to-digital converter for digital sampling.

[0010] The sensing electrical signal with m modulation periods T is digitally sampled, and the sampled values ​​within the time interval mT are demodulated to obtain the modulation depth error and feedback phase error.

[0011] A sine wave is generated based on the modulation depth error;

[0012] The feedback phase error is processed over N modulation periods T to generate a sawtooth wave, where N = nm and n is a positive integer;

[0013] The generated sine wave is superimposed with a sawtooth wave and provided to a digital-to-analog converter to form a modulation signal.

[0014] The modulation signal is converted into an electrical signal by a digital-to-analog converter, and the electrical signal is used to realize closed-loop control of the fiber optic current transformer.

[0015] Furthermore, the step of converting the interference optical path signal into a sensing electrical signal and sending it to the analog-to-digital converter for digital sampling includes:

[0016] The interference optical path signal is converted into a sensing electrical signal by a photodetector;

[0017] The sensing electrical signal is passed through a preamplifier circuit and then enters the analog-to-digital converter.

[0018] Furthermore, the demodulation of the sampled values ​​within the mT time period includes the following steps:

[0019] Based on the digital phase-sensitive detection method, the sampled values ​​of the interference optical path signal for m modulation periods T are digitally demodulated, and the amplitudes H of the first, second, and fourth harmonics are taken respectively. 1i H 2i and H 4i ;

[0020] Based on the ratio of second- and fourth-order Bessel functions With modulation depth Correspondence, combined with the ratio of the second and fourth harmonics Calculate modulation depth

[0021] Calculate the feedback phase error using the formula. The calculation formula is as follows:

[0022]

[0023] Further, generating a sine wave based on the modulation depth error includes the following steps:

[0024] The period of the sine wave is set to be the modulation period T, and the amplitude of the sine wave is adjusted every mT interval.

[0025] According to modulation depth The modulation depth error was calculated. in Modulation depth for the target;

[0026] According to the modulation depth error Calculate the amplitude error of a sine wave Where k is the gain coefficient of the sine wave amplitude.

[0027] Furthermore, the feedback phase error processing for N modulation periods T to generate a sawtooth wave includes the following steps:

[0028] Set the sawtooth wave period to N modulation periods T, and set the sawtooth wave amplitude to be adjusted every NT interval;

[0029] According to the feedback phase error Calculate feedback phase offset

[0030] According to the feedback phase offset Calculate the error of sawtooth wave amplitude Where h is the gain coefficient of the sawtooth wave amplitude.

[0031] Furthermore, the calculation of the feedback phase offset Includes the following steps:

[0032] The phase error is fed back using the demodulated value within m modulation periods T. Using this as the basic unit, the sampled values ​​of N modulation periods T are analyzed to calculate n feedback phase errors.

[0033] Since there is a sawtooth wave voltage jump during sawtooth wave switching, it is assumed that j feedback phase errors are generated within the transit time τ after the jump. Where j = [τ / mT], and [] denotes rounding up from n feedback phase errors. The j-th wave pulses within the transit time τ after the voltage jump are removed from the middle.

[0034] Again, for the remaining (nj) feedback phase errors Perform filtering to remove the maximum value. and minimum value The feedback phase offset is then:

[0035]

[0036] Furthermore, the modulation signal obtained by superimposing the sine wave and the sawtooth wave includes:

[0037]

[0038] Here, sawtooth() represents an amplitude of 1 with a period of mnT. V is a sawtooth wave voltage signal with initial phase. sm V tm These represent the amplitude values ​​of the sine wave and the sawtooth wave, respectively, for the previous time period. The initial phases of the sine wave and the sawtooth wave are ΔV, respectively. ism Let ΔV be the amplitude error of the sine wave during the time interval imT~(i+1)mT. imnt The error of the sawtooth wave amplitude during the time period from imnT to (i+1)mnT is denoted as .

[0039] Furthermore, when measuring current, a first phase-locked loop is formed by a sinusoidal modulation signal with a period of T and a sinusoidal amplitude error signal with a period of mT, enabling a rapid response to the current under test.

[0040] A second phase-locked loop is formed by a sawtooth wave modulation signal with a period of mnT and a sawtooth wave amplitude error signal with the same period, so that the fiber optic current transformer operates near its highest sensitivity.

[0041] Furthermore, the digital-to-analog converter converts the modulation signal into an electrical signal. The electrical signal converted by the digital-to-analog converter is then amplified by a gain amplifier circuit and applied to the optical phase modulator in the fiber optic current transformer to form the modulation phase in the interference optical path.

[0042] The present invention also includes a phase-locked loop control device for an optical fiber current transformer, using the method described above, comprising:

[0043] A sampling unit is used to form an interference optical path signal after being modulated by an electrical signal, and to convert the interference optical path signal into a sensing electrical signal and send it to an analog-to-digital converter for digital sampling.

[0044] The demodulation unit is used to process the sensing electrical signal with m modulation periods T and demodulate the sampled values ​​within the mT time period to obtain the modulation depth error and the feedback phase error.

[0045] A sine wave generation unit is used to generate a sine wave based on the modulation depth error;

[0046] A sawtooth wave generation unit is used to process the feedback phase error of N modulation periods T to generate a sawtooth wave, where N = nm and n is a positive integer;

[0047] A modulation unit is used to superimpose the generated sine wave and sawtooth wave and provide them to a digital-to-analog converter to form a modulation signal.

[0048] A conversion unit is used to convert the modulation signal into an electrical signal through a digital-to-analog converter, thereby realizing closed-loop control of the fiber optic current transformer.

[0049] The present invention also includes a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method as described above.

[0050] The present invention also includes a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method as described above.

[0051] The beneficial effects of this invention are as follows: This invention uses a high-frequency sine wave signal for modulation, modulating the interference optical path signal carrying the information of the current to be measured into a high-frequency carrier signal. By digitally demodulating the harmonic components in the interference optical path signal, on the one hand, the feedback phase error is calculated and used as the measurement output of the current transformer to achieve a fast response to the current to be measured; on the other hand, the sine wave modulation depth error and sine wave amplitude error are calculated and used as the sine wave amplitude feedback adjustment input to form a first phase-locked loop system. A low-frequency sawtooth wave signal is used for modulation to generate a feedback phase with the same magnitude but opposite direction as the Faraday phase shift caused by the current to be measured, so that the current transformer operates near its highest sensitivity. Combined with the demodulated feedback phase error and sawtooth wave amplitude error, these are used as the sawtooth wave amplitude feedback adjustment input to form a second phase-locked loop system. This invention achieves the low bandwidth adaptability requirements of the fiber optic current transformer to the modulation and demodulation circuit, improves the measurement accuracy and dynamic range of the current transformer, and effectively reduces the design and manufacturing difficulty and product cost of the current transformer. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a flowchart of the method in this embodiment;

[0054] Figure 2 This is a schematic diagram of the device in this embodiment;

[0055] Figure 3This is the digital phase-locked loop control process for the fiber optic current transformer in this embodiment;

[0056] Figure 4 The waveforms of the sinusoidal modulation signal and the interference optical path signal in this embodiment are shown.

[0057] Figure 5 The graphs show the first-order, second-order, and fourth-order Bessel functions in this embodiment.

[0058] Figure 6 The waveforms of the sawtooth wave modulation signal and the interference optical path signal in this embodiment are shown.

[0059] Figure 7 This is a schematic diagram of the superposition of sine wave and sawtooth wave modulated signals in this embodiment.

[0060] Figure 8 This is a schematic diagram of the computer device in this embodiment. Detailed Implementation

[0061] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0062] like Figure 1 As shown: A phase-locked loop control method for an optical fiber current transformer includes the following steps:

[0063] In the fiber optic current sensor, the input optical signal entering the modulator is modulated by an electrical signal to form an interference optical path signal. The interference optical path signal is then converted into a sensing electrical signal and sent to the analog-to-digital converter for digital sampling.

[0064] The sensing electrical signal with m modulation periods T is digitally sampled, and the sampled values ​​within the time interval mT are demodulated to obtain the modulation depth error and feedback phase error.

[0065] Based on the modulation depth error, a sine wave is generated;

[0066] Feedback phase error processing for N modulation periods T generates a sawtooth wave, where N = nm and n is a positive integer;

[0067] The generated sine wave and sawtooth wave are superimposed and provided to the digital-to-analog converter to form a modulation signal;

[0068] The modulated signal is converted into an electrical signal by a digital-to-analog converter, and the electrical signal is used to realize the closed-loop control of the fiber optic current transformer.

[0069] In this embodiment, the process of converting the interference optical path signal into a sensing electrical signal and sending it to the analog-to-digital converter for digital sampling includes:

[0070] The interference optical path signal is converted into a sensing electrical signal by a photodetector;

[0071] The sensor signal is passed through a preamplifier circuit and then enters the analog-to-digital converter.

[0072] Demodulating the sampled values ​​within the mT time interval includes the following steps:

[0073] Based on the digital phase-sensitive detection method, the sampled values ​​of the interference optical path signal with m modulation periods T are digitally demodulated, and the amplitudes H of the first, second, and fourth harmonics are taken respectively. 1i H 2i and H 4i ;

[0074] Based on the ratio of second- and fourth-order Bessel functions With modulation depth Correspondence, combined with the ratio of the second and fourth harmonics Calculate modulation depth

[0075] Calculate the feedback phase error using the formula. The calculation formula is as follows:

[0076]

[0077] Based on the modulation depth error, a sine wave is generated, including the following steps:

[0078] The period of the sine wave is set to be the modulation period T, and the amplitude of the sine wave is adjusted every mT interval.

[0079] According to modulation depth The modulation depth error was calculated. in Modulation depth for the target;

[0080] Based on modulation depth error Calculate the amplitude error of a sine wave Where k is the gain coefficient of the sine wave amplitude.

[0081] The feedback phase error processing for N modulation periods T generates a sawtooth wave, including the following steps:

[0082] Set the sawtooth wave period to N modulation periods T, and set the sawtooth wave amplitude to be adjusted every NT interval;

[0083] Based on feedback phase error Calculate feedback phase offset

[0084] Based on feedback phase offset Calculate the error of sawtooth wave amplitude Where h is the gain coefficient of the sawtooth wave amplitude.

[0085] Calculate feedback phase offset Includes the following steps:

[0086] The phase error is fed back using the demodulated value within m modulation periods T. Using this as the basic unit, the sampled values ​​of N modulation periods T are analyzed to calculate n feedback phase errors.

[0087] Since there is a sawtooth wave voltage jump during sawtooth wave switching, it is assumed that j feedback phase errors are generated within the transit time τ after the jump. Where j = [τ / mT], and [] denotes rounding up from n feedback phase errors. The j-th wave pulses within the transit time τ after the voltage jump are removed from the middle.

[0088] Again, for the remaining (nj) feedback phase errors Perform filtering to remove the maximum value. and minimum value The feedback phase offset is then:

[0089]

[0090] The modulated signal resulting from the superposition of a sine wave and a sawtooth wave includes:

[0091]

[0092] Here, sawtooth() represents an amplitude of 1 with a period of mnT. V is a sawtooth wave voltage signal with initial phase. sm V tm These represent the amplitude values ​​of the sine wave and the sawtooth wave, respectively, for the previous time period. The initial phases of the sine wave and the sawtooth wave are ΔV, respectively. ism Let ΔV be the amplitude error of the sine wave during the time interval imT~(i+1)mT. imnt The error of the sawtooth wave amplitude during the time period from imnT to (i+1)mnT is denoted as .

[0093] When measuring current, a first phase-locked loop is formed by a sinusoidal modulation signal with period T and a sinusoidal amplitude adjustment signal with period mT, which enables a fast response to the current under test.

[0094] A second phase-locked loop is formed by a sawtooth wave modulation signal with a period of mnT and a sawtooth wave amplitude adjustment signal with the same period, so that the fiber optic current transformer operates near its highest sensitivity.

[0095] The digital-to-analog converter converts the modulated signal into an electrical signal. After the electrical signal converted by the digital-to-analog converter is amplified by the gain amplifier circuit, it is applied to the optical phase modulator in the fiber optic current transformer to form the modulated phase in the interference optical path.

[0096] In this embodiment, a high-frequency sinusoidal signal is used for modulation. The interference optical path signal carrying the information of the current to be measured is modulated into a high-frequency carrier signal. By digitally demodulating the harmonic components in the interference optical path signal, the feedback phase error is calculated and used as the measurement output of the current transformer to achieve a fast response to the current to be measured. On the other hand, the sinusoidal modulation depth error is calculated and used as the sinusoidal amplitude feedback adjustment input to form a first phase-locked loop system. A low-frequency sawtooth wave signal is used for modulation to generate a feedback phase with the same magnitude but opposite direction as the Faraday phase shift caused by the current to be measured. This allows the current transformer to operate near its highest sensitivity. Combined with the feedback phase error obtained from demodulation, it is used as the sawtooth wave amplitude feedback adjustment input to form a second phase-locked loop system. This invention realizes the low bandwidth adaptability requirements of the fiber optic current transformer to the modulation and demodulation circuit, improves the measurement accuracy and dynamic range of the current transformer, and effectively reduces the design and manufacturing difficulty and product cost of the current transformer.

[0097] like Figure 2 As shown, this embodiment also includes a phase-locked loop control device for an optical fiber current transformer, which uses the method described above, including:

[0098] The sampling unit is used to generate an interference optical path signal after being modulated by an electrical signal, and to convert the interference optical path signal into a sensing electrical signal and send it to the analog-to-digital converter for digital sampling.

[0099] The demodulation unit processes the sensing electrical signal with m modulation periods T and demodulates the sampled values ​​within the mT time period to obtain the modulation depth error and feedback phase error.

[0100] The sine wave generation unit is used to generate a sine wave based on the modulation depth error.

[0101] The sawtooth wave generation unit is used to process the feedback phase error of N modulation periods T and generate a sawtooth wave, where N = nm and n is a positive integer.

[0102] The modulation unit is used to superimpose the generated sine wave and sawtooth wave and provide them to the digital-to-analog converter to form a modulation signal.

[0103] The conversion unit is used to convert the modulated signal into an electrical signal through a digital-to-analog converter, thereby realizing the closed-loop control of the fiber optic current transformer.

[0104] like Figure 3As shown, the sinusoidal modulation signal generation / adjustment method proposed in this embodiment is as follows:

[0105] The period of the generated sine wave is the modulation period T;

[0106] Based on the ratio of second- and fourth-order Bessel functions With modulation depth Correspondence, combined with the ratio of the second and fourth harmonics Calculate modulation depth

[0107] According to modulation depth The modulation depth error was calculated. To determine the target modulation depth, the amplitude error of the sinusoidal wave is then calculated. k is the gain coefficient, assuming the amplitude of the sine wave in the previous time period is V. sm The generated sine wave amplitude is (V sm +ΔV ism The amplitude of the sine wave is adjusted every mT time interval, and the generated sine wave modulation signal is...

[0108]

[0109] The modulation phase generated by the sinusoidal modulation signal is proportional to the sinusoidal modulation voltage.

[0110]

[0111] The sawtooth wave modulation signal generation / adjustment method proposed in this invention is as follows:

[0112] Based on first- and second-order Bessel functions and the amplitudes of the first and second harmonics H 1i H 2i Calculate feedback phase error The calculation formula is as follows:

[0113]

[0114] By analyzing the sampled values ​​of N modulation periods T (or mnT), n feedback phase errors can be calculated.

[0115] Since there is a sawtooth wave voltage jump during sawtooth wave switching, it is assumed that j feedback phase errors are generated within the transit time τ after the jump. Where j = [τ / mT], and [] denotes rounding up from n feedback phase errors. J are removed after the sawtooth wave voltage jump;

[0116] Again, for the remaining (nj) feedback phase errors Perform filtering to remove the maximum value. and minimum value Then feedback phase shift

[0117]

[0118] Sawtooth wave amplitude error h is the gain coefficient, assuming the sawtooth wave amplitude in the previous time period is V. tm The generated sawtooth wave amplitude value is (V tm +ΔV imnt The sawtooth wave amplitude is adjusted every NT (or mnT) intervals, the sawtooth wave period is NT (or mnT), and the generated sawtooth wave modulation signal is...

[0119]

[0120] The modulation phase generated by the sawtooth wave modulation signal is proportional to the sawtooth wave modulation voltage.

[0121]

[0122] The modulation signal obtained by superimposing the sine wave and sawtooth wave signals proposed in this invention is as follows:

[0123]

[0124] Here, sawtooth() represents an amplitude of 1 with a period of mnT. V is a sawtooth wave voltage signal with initial phase. sm V tm These represent the amplitude values ​​of the sine wave and sawtooth wave from the previous time period, respectively. The initial phases of the sine wave and the sawtooth wave are ΔV, respectively. ism Let ΔV be the amplitude error of the sine wave during the time interval imT~(i+1)mT. imnt The error of the sawtooth wave amplitude during the time period from imnT to (i+1)mnT is denoted as .

[0125] Based on the aforementioned digital phase-locked loop control method, when the fiber optic current transformer uses sinusoidal and sawtooth wave modulation signals, the interference optical path signal output by the photodetector is:

[0126]

[0127] In formula (8) The Faraday phase shift generated by the current under test is the feedback phase generated by the sinusoidal and sawtooth wave modulated signals. in τ represents the modulation phase generated by the sinusoidal and sawtooth wave modulation signals, respectively, and τ is the round-trip transit time of the optical signal transmitted in the mutual inductor.

[0128] For the first digital phase-locked loop control, when using sinusoidal signal modulation, the modulation phase difference formed in the interference optical path signal is:

[0129]

[0130] In equation (9) V represents the modulation depth of the sine wave. sm K represents the amplitude of the sine wave. sm Let T be the modulation coefficient of the phase modulator, and let T be the modulation period of the sine wave.

[0131] Substituting equation (9) into equation (8), we can obtain that the interference optical path signal can be rewritten as follows:

[0132]

[0133] In the above formula This represents the feedback phase error between the Faraday phase shift and the phase of the sawtooth wave modulated signal.

[0134] Applying the first-type Bessel function expansion (10), the interference optical path signal can be further expressed as:

[0135]

[0136] In the above formula, J x Let x represent the first-order Bessel function of the first kind. From equation (11), it can be seen that the feedback phase error... When the value is zero, the output signal contains only even harmonics of the modulation frequency; feedback phase error When the value is not zero, odd harmonics of the modulation frequency will appear in the output optical signal, as shown in the attached figure. Figure 4 As shown.

[0137] Based on the digital phase-sensitive detection method, the amplitudes of the first, second, and fourth harmonic components of the demodulated interference optical path signal are:

[0138]

[0139] In the above formula, K a It represents the gain coefficient of the interference optical signal after passing through the photodetector, preamplifier circuit and analog-to-digital converter.

[0140] The first, second, and fourth order Bessel function curves and the second and fourth order ratios are attached. Figure 5 As shown. Based on the ratio of second- and fourth-order Bessel functions. With modulation depth Correspondence, combined with the amplitude ratio of the second and fourth harmonics Modulation depth for

[0141]

[0142] Assuming the target modulation depth is The modulation depth error was calculated. According to equation (9), the modulation depth With the amplitude V of the sine wave sm Linear correlation is used to calculate the amplitude error of the sine wave. k is the gain coefficient. Assume the amplitude of the sine wave in the previous time period was V. sm The amplitude of the sine wave after feedback is (V sm +ΔV sm The amplitude of the sine wave is adjusted every mT time interval, thus generating a sinusoidal modulated signal.

[0143]

[0144] The modulation phase generated by the sinusoidal signal is proportional to the sinusoidal modulation voltage.

[0145]

[0146] For the second digital phase-locked loop control, when using sawtooth wave signal modulation, as shown in the attached... Figure 6 As shown. Assume the sawtooth wave amplitude is V. tm The modulation period is mnT. Within one modulation period, the modulation phase difference generated in the time interval (mnT-τ) is related to V. tm • τ / mnT are linearly correlated, and the modulation phase difference during the τ time interval is related to -V tm (mnT-τ) / mnT are linearly dependent, and we have

[0147]

[0148] As shown in equation (12), the sampled values ​​within the i-th mT time period are demodulated based on the first and second harmonic amplitudes H. 1i H 2i and first- and second-order Bessel functions Demodulation feedback phase error for

[0149]

[0150] By analyzing the sampled values ​​within one modulation period mnT of the sawtooth wave, n feedback phase errors can be calculated. Since there is a sawtooth wave voltage jump during the switching of the sawtooth wave signal, it is assumed that j feedback phase errors are generated within the transit time τ after the jump. Where j = [τ / mT], and [] denotes rounding up from n feedback phase errors. Remove j sawtooth wave voltage jumps from the data; then process the remaining (nj) feedback phase errors. Perform filtering to remove the maximum value. and minimum value Then feedback phase shift

[0151]

[0152] According to equation (16), the sawtooth wave modulation phase With sawtooth wave amplitude V tm Linear correlation allows for the calculation of the sawtooth wave amplitude error. h is the gain coefficient. Assume the sawtooth wave amplitude in the previous time period was V. tm The sawtooth wave period is mnT, and the amplitude of the sawtooth wave after feedback adjustment is (V tm +ΔV mnt The sawtooth wave amplitude is adjusted every mnT time interval, with an initial phase of... The generated sawtooth wave modulated signal is

[0153]

[0154] The modulation phase generated by the sawtooth wave modulation signal is proportional to the sawtooth wave modulation voltage.

[0155]

[0156] As attached Figure 7 As shown, the modulated signal formed by the superposition of a sine wave and a sawtooth wave is:

[0157]

[0158] In summary, on the one hand, feedback phase error is adopted. Sawtooth wave modulation phase As the demodulated output of the measured current, it enables a rapid response to the measured current. On the other hand, it feeds back the phase error. Used as feedback input for sawtooth wave modulation signals, resulting in a Faraday phase shift. Phase modulation with sawtooth wave The difference between Approximately zero, as can be seen from the first harmonic component in equation (12), the current transformer always operates at its highest sensitivity point, improving the measurement accuracy and dynamic range of the current transformer. In addition, the use of high-frequency sine wave modulation signals and low-frequency sawtooth wave modulation signals effectively reduces the bandwidth requirements of the system modulation and demodulation circuit and the design and manufacturing costs of the current transformer product.

[0159] Please see Figure 8The diagram shows a structural schematic of a computer device provided in an embodiment of this application. An embodiment of this application provides a computer device 400, including a processor 410 and a memory 420. The memory 420 stores a computer program executable by the processor 410. When the computer program is executed by the processor 410, it performs the method described above.

[0160] This application embodiment also provides a storage medium 430, on which a computer program is stored, and the computer program is executed by a processor 410 to perform the above method.

[0161] The storage medium 430 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0162] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0163] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0164] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0165] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0166] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0167] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0168] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0169] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A phase-locked loop control method for an optical fiber current transformer, characterized in that, Includes the following steps: The input optical signal entering the modulator in the fiber optic current transformer is modulated by an electrical signal to form an interference optical path signal. The interference optical path signal is then converted into a sensing electrical signal and digitally sampled. The sensing electrical signal with m modulation periods T is digitally sampled, and the sampled values ​​within the time interval mT are demodulated to obtain the modulation depth error and feedback phase error. A sine wave is generated based on the modulation depth error; The feedback phase error processing for N modulation periods T generates a sawtooth wave, where N = nm and n is a positive integer; The generated sine wave and sawtooth wave are superimposed at a set period to form a modulation signal; The modulation signal is converted into an electrical signal, and the electrical signal is used to realize the closed-loop control of the fiber optic current transformer. The feedback phase error processing for N modulation periods T to generate a sawtooth wave includes the following steps: Set the sawtooth wave period to N modulation periods T, and set the sawtooth wave amplitude to be adjusted every NT interval; According to the feedback phase error Δφ fi Calculate the feedback phase offset ; According to the feedback phase offset Calculate the error of sawtooth wave amplitude , where h is the gain coefficient of the sawtooth wave amplitude; The calculation feedback phase offset It includes the following steps: The phase error Δφ is fed back using the demodulated value within m modulation periods T. fi Using this as the basic unit, the sampled values ​​of N modulation periods T are analyzed to calculate n feedback phase errors Δφ. fi ; Since there is a sawtooth wave voltage jump during sawtooth wave switching, it is assumed that j feedback phase errors Δφ are generated within the transit time τ after the jump. fi Where j=[τ / mT], [] denotes rounding up from n feedback phase errors Δφ fi The j-th wave pulses within the transit time τ after the voltage jump are removed from the middle. Again, consider the remaining (nj) feedback phase errors Δφ fi Perform filtering to remove the maximum value Δφ. fi | max and minimum value Δφ fi | min The feedback phase offset is then: 。 2. The phase-locked loop control method for fiber optic current transformers according to claim 1, characterized in that, The demodulation of the sampled values ​​within the mT time period includes the following steps: Based on the digital phase-sensitive detection method, the interference optical path signal with m modulation periods T is digitally processed, and the amplitudes H of the first, second, and fourth harmonics are taken respectively. 1i H 2i and H 4i ; Based on the ratio J2(φ) of second- and fourth-order Bessel functions mdi ) / J4(φ mdi ) and modulation depth φ mdi The correspondence is based on the second and fourth harmonic ratios satisfying |H 2i / H 4i | = J2(φ mdi ) / J4(φ mdi ), calculate the modulation depth φ mdi ; The feedback phase error Δφ is calculated using the formula. fi The calculation formula is as follows: 。 3. The phase-locked loop control method for fiber optic current transformers according to claim 2, characterized in that, The step of generating a sine wave based on the modulation depth error includes the following steps: Set the sine wave period to the modulation period T, and set the sine wave amplitude to be adjusted every mT interval; According to the modulation depth φ mdi The modulation depth error Δφ is calculated. mdi =φ mdi -φ md0 , where φ md0 Modulation depth for the target; According to the modulation depth error Δφ mdi Calculate the amplitude error ΔV of the sine wave ism =k·Δφ mdi , where k is the gain coefficient of the sine wave amplitude.

4. The phase-locked loop control method for fiber optic current transformers according to claim 1, characterized in that, The modulation signal obtained by superimposing the sine wave and the sawtooth wave includes: ； Where sawtooth() represents an amplitude of 1, a period of mnT, and V sm V tm These are the amplitudes of the sine wave and sawtooth wave in the previous time period, respectively. φ0 and φ1 are the initial phases of the sine wave and sawtooth wave, respectively. ΔV ism Let ΔV be the amplitude error of the sine wave during the time interval imT ~ (i+1)mT. imnt The error of the sawtooth wave amplitude during the time period imnT ~ (i+1)mnT is denoted as .

5. The phase-locked loop control method for fiber optic current transformers according to claim 1, characterized in that, When measuring current, a first phase-locked loop is formed by a sinusoidal modulation signal with a period of T and a sinusoidal amplitude error signal with a period of mT. A second phase-locked loop is formed by a sawtooth wave modulation signal with a period of mnT and a sawtooth wave amplitude error signal with the same period.

6. A phase-locked loop control device for an optical fiber current transformer, characterized in that, Using the method as described in claim 1 includes: A sampling unit is used to form an interference optical path signal after being modulated by an electrical signal, and to convert the interference optical path signal into a sensing electrical signal and send it to an analog-to-digital converter for digital sampling. The demodulation unit is used to process the sensing electrical signal with m modulation periods T and demodulate the sampled values ​​within the mT time period to obtain the modulation depth error and the feedback phase error. A sine wave generation unit is used to generate a sine wave based on the modulation depth error; A sawtooth wave generation unit is used to process the feedback phase error of N modulation periods T to generate a sawtooth wave, where N=nm and n is a positive integer; A modulation unit is used to superimpose the generated sine wave and sawtooth wave and provide them to a digital-to-analog converter to form a modulation signal. A conversion unit is used to convert the modulated signal into an electrical signal through a digital-to-analog converter, thereby realizing closed-loop control of the fiber optic current transformer.

7. The phase-locked loop control device for fiber optic current transformers according to claim 6, characterized in that, The digital-to-analog converter converts the modulation signal into an electrical signal. After the electrical signal converted by the digital-to-analog converter is amplified by the gain amplifier circuit, it is applied to the optical phase modulator in the fiber optic current transformer to form the modulation phase in the interference optical path.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-5.

9. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method as described in any one of claims 1-5.

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