Optical fiber current sensor harmonic superposition test system, method and measurement system

Abstract

The application discloses a kind of optical fiber current sensor harmonic superposition test system, method and measuring system, test system obtains superposed current light signal or single current light signal by optical fiber coil, and is sent to FOCT collector, FOCT collector outputs digital or analog signal, digital signal or analog signal is sent to error operation processing module after conversion channel conversion, the digital signal that current waveform exported by current signal source is sent to error operation processing module after conversion channel conversion after standard device, error operation processing module carries out synchronous error calculation according to the digital signal of first conversion channel transmission and the digital signal (or the digital signal that is output after second conversion channel) of FOCT collector, can display power frequency accuracy, direct current accuracy, harmonic accuracy, single component waveform, superposed current waveform, and is superior to the single harmonic accuracy and waveform that only display of existing harmonic measuring equipment.

Description

Technical Field

[0001] This invention belongs to the field of power measurement technology, specifically relating to a fiber optic current sensor harmonic superposition testing system, method, and measurement system. Background Technology

[0002] Research on power system harmonics began in the 1950s, focusing on harmonics caused by converters in high-voltage direct current (HVDC) transmission technology. In the 1970s, with the development of power electronics technology and its widespread application in industry, transportation, and households, the potential threat posed by harmonics to the safety, stability, and economic operation of power systems became increasingly serious, significantly impacting the surrounding electrical environment. Harmonic pollution is now considered a major public nuisance of power grids, attracting significant attention worldwide. Research on harmonics covers a wide range of topics, including methods for analyzing distorted waveforms, harmonic source analysis, harmonic measurement, methods for measuring various electrical quantities under harmonic conditions, power grid harmonic flow calculations, harmonic compensation and suppression, and harmonic limitation standards. Harmonic measurement is a crucial branch of harmonic research and serves as the starting point and primary basis for its analysis. Due to the nonlinearity, randomness, distribution, non-stationarity, and complexity of influencing factors, accurate measurement of harmonics is challenging.

[0003] With the increasing complexity and diversification of power electronics technology, a large number of power electronic devices with impulsive, nonlinear, and unbalanced characteristics have led to the continuous deterioration of power quality in distribution networks. Furthermore, the power quality disturbances brought about by the electrification process in the 21st century are even more intricate, with uncertain sources and interactions between the generated disturbances. These disturbances affect the probability of electromagnetic interference, causing numerous new power quality problems: such as rapid voltage changes, more frequent three-phase imbalances, a significant increase in interharmonics, low-frequency subharmonics, and ultra-high-frequency harmonics above 2kHz, and a shift of non-power frequency components towards the subsynchronous and high-frequency bands. Traditional electromagnetic instrument transformers can no longer meet the complex measurement requirements.

[0004] As a phase-modulated fiber optic current sensor, it converts changes in current into changes in the phase of light waves in the optical fiber, detecting the current passing through the sensing loop through coherent detection and digital closed-loop feedback technology. Fiber optic current sensors possess a series of advantages, including good insulation performance, small size, light weight, large measurement range, good dynamic characteristics, full digitalization, and the ability to simultaneously measure AC and DC signals. They have unique technical advantages in current measurement under complex electromagnetic environments such as ultra-high voltage DC projects, flexible DC transmission projects, next-generation smart substations, metallurgy, electrochemistry, power generation, nuclear physics, pulse power, and pipeline cathodic protection. The wideband advantage of fiber optic current sensors also provides technical support for the accurate measurement of high-order harmonics in power grids.

[0005] Existing harmonic calibration methods for fiber optic current sensors are mainly based on the measurement of single harmonics. A transconductance amplifier generates a single harmonic current of 50Hz to 1200Hz. The current conductor passes through the sensing loop and is connected to a precision shunt. The harmonic measurement equipment can simultaneously acquire the digital output of the fiber optic current sensor and the voltage across the precision shunt. After calculation, the harmonic accuracy and waveform are displayed.

[0006] With the widespread application of power electronics technology in power systems and the large-scale integration of new energy sources into the grid, the number and capacity of nonlinear loads are increasing, leading to a significant injection of harmonics into the grid. This places higher demands on the accurate measurement of harmonic currents. Currently, 40% of harmonics are generated by rectifier devices, and most harmonics are mixed in with power frequency or DC signals. The composite signals resulting from multiple power frequency, DC, and multiple harmonic superpositions cannot be simulated or tested using existing technologies, making it difficult to fully verify the harmonic measurement performance of the equipment under test. Summary of the Invention

[0007] The purpose of this invention is to provide a harmonic superposition test system, method, and measurement system for fiber optic current sensors, in order to solve the problem that existing technologies cannot simulate and test composite signals with multiple power frequencies, DC, and multiple harmonic superpositions, making it difficult to fully verify the harmonic measurement performance of the device under test.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A first aspect of the present invention provides a fiber optic current sensor harmonic superposition testing system, comprising:

[0010] A current signal source, used to output different types of current waveforms;

[0011] The data acquisition module includes an FOCT acquisition unit, a standard, a first conversion channel, a second conversion channel, a digital channel, and an optical fiber coil;

[0012] The data analysis waveform display module includes an error calculation and processing module, a synchronization pulse source, and a display module;

[0013] The current signal source is sequentially connected to the standard, the first conversion channel, and the error calculation and processing module. It is used to convert the output current waveform into a digital signal through the first conversion channel after passing through the standard and then transmit it to the error calculation and processing module.

[0014] The optical signal output terminal of the optical fiber coil is connected to the FOCT acquisition unit. The optical fiber coil is used to be wound on the conductor under test and send the corresponding superimposed current optical signal or single current optical signal to the FOCT acquisition unit. The FOCT acquisition unit is connected to the error calculation and processing module through the second conversion channel or digital channel.

[0015] The error calculation and processing module is used to calculate the synchronization error based on the digital signal transmitted through the first conversion channel and the output signal of the FOCT collector under the synchronization of the synchronization pulse source, and obtain the power frequency accuracy, DC accuracy, harmonic accuracy, single component waveform, and superimposed waveform, respectively, and display them on the display module.

[0016] As an optional embodiment of the present invention, the current signal source includes a variety of different types of current sources, and outputs at least two of the following: DC current, AC current, and harmonic current.

[0017] As an optional solution of the present invention, the optical fiber coil is configured as follows: multiple optical fiber coils are connected in series and then wound on multiple different current conductors; or a single optical fiber coil is wound on multiple current conductors at the same time; or a single optical fiber coil is wound on a single current conductor.

[0018] As an optional solution of the present invention, when the optical fiber coil is configured such that multiple optical fiber coils are connected in series and wound on multiple different current conductors, the light source in the FOCT collector is connected to the first optical signal end of the series optical fiber coil in sequence through a polarization-maintaining optical fiber jumper, a quarter wave plate, and a single-mode optical fiber jumper, and the second optical signal end of the series optical fiber coil is connected to a reflector.

[0019] As an optional embodiment of the present invention, when multiple fiber optic coils are connected in series, the first fiber optic coil is connected to a quarter-wave plate through a fiber optic patch cord flange adapter box, the last fiber optic coil is connected to a reflector through a fiber optic patch cord flange adapter box, and the middle fiber optic coil is connected in series with the first and last fiber optic coils in the fiber optic patch cord flange adapter box.

[0020] As an optional solution of the present invention, when a single optical fiber coil is simultaneously wound on multiple current conductors, the light source in the FOCT collector is connected to the first optical signal end of the single optical fiber coil in sequence through a polarization-maintaining optical fiber jumper, a quarter-wave plate, and a single-mode optical fiber jumper, and the second optical signal end of the single optical fiber coil is connected to a reflector.

[0021] As an optional solution of the present invention, when a single optical fiber coil is wound on a current conductor, the light source in the FOCT collector is connected to the first optical signal end of the single optical fiber coil in sequence through a polarization-maintaining optical fiber jumper, a quarter-wave plate, and a single-mode optical fiber jumper, and the second optical signal end of the single optical fiber coil is connected to a reflector.

[0022] As an optional solution of the present invention, when the current signal source output current is ≤120A, it is directly connected to the standard; when the current source output current is >120A, it is connected to the standard after current conversion.

[0023] A second aspect of the present invention provides a method for testing harmonic superposition in an optical fiber current sensor, based on the aforementioned optical fiber current sensor harmonic superposition testing system, specifically including the following steps:

[0024] Different types of current waveforms output by the current signal source are transmitted to the first conversion channel after passing through a standard;

[0025] The first conversion channel converts the actual value of the current waveform of a single current into a digital value and sends it to the error calculation and processing module;

[0026] The fiber optic coil sends a superimposed current optical signal or a single current optical signal to the FOCT collector. The FOCT collector then transmits the digital quantity corresponding to the superimposed current optical signal or the single current optical signal to the error calculation and processing module through the second conversion channel or the digital quantity channel.

[0027] Under the synchronization of the synchronization pulse source, the error calculation and processing module performs synchronization error calculation based on the digital signal transmitted by the first conversion channel and the output signal of the FOCT acquisition unit, and obtains the power frequency accuracy, DC accuracy, harmonic accuracy, single component waveform, and superimposed waveform, which are then displayed on the display module.

[0028] A third aspect of the present invention provides a superimposed current measurement system, comprising:

[0029] The data acquisition module includes an FOCT acquisition unit, a second conversion channel, a digital channel, and an optical fiber coil;

[0030] The data analysis waveform display module includes an error calculation and processing module and a display module;

[0031] The optical signal output terminal of the fiber optic coil is connected to the FOCT acquisition unit. The fiber optic coil is used to be wound on the conductor under test and send the corresponding optical signal to the FOCT acquisition unit. The FOCT acquisition unit is connected to the error calculation and processing module through the second conversion channel or the digital signal channel. The fiber optic coil is configured in the following ways: multiple fiber optic coils are connected in series and wound on multiple different current conductors; or a single fiber optic coil is wound on multiple current conductors at the same time; or a single fiber optic coil is wound on a single current conductor.

[0032] The error calculation and processing module is used to calculate the output signal of the FOCT acquisition unit to obtain a single current waveform or a superimposed current waveform, and display it on the display module.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1) The fiber optic current sensor harmonic superposition testing system provided by this invention acquires superimposed current optical signals or single current optical signals through an optical fiber coil and sends them to an FOCT (Optical Current Transmitter) acquisition unit. The FOCT acquisition unit outputs digital or analog signals. The analog signals are converted by a conversion channel and then sent to an error calculation and processing module. Simultaneously, the current waveform output by the current signal source is converted into a digital signal by a standard and a conversion channel and then sent to the error calculation and processing module. The error calculation and processing module performs synchronous error calculation based on the digital signal transmitted through the first conversion channel and the output signal of the FOCT acquisition unit. It can display power frequency accuracy, DC accuracy, harmonic accuracy, single component waveform, and superimposed waveform, which is superior to existing harmonic measurement equipment that only displays harmonic accuracy and waveform. It has a large measurement dynamic range, and the superimposed waveform does not affect the harmonic measurement accuracy. Furthermore, by using a digital channel and a conversion channel, it can perform both digital and analog measurements, allowing for selective testing.

[0035] 2) The fiber optic current sensor harmonic superposition testing system provided by this invention, when testing the fiber optic current sensor, uses a single-mode jumper system to connect the fiber optic coil and the closure point (reflector and quarter-wave plate) of the optical measurement system, realizing multi-state integrated combined testing, which is small in size and light in weight. Compared with existing measurement equipment, it has significant advantages such as large overall size and single testing.

[0036] 3) The fiber optic current sensor harmonic superposition test system provided by the present invention has a standard connected in series between the current source and the single current conversion channel to perform current conversion on the current output of the current source. The standard is used to collect the current source signal, and the measurement range ≤120V is better than the existing ≤10V measurement range.

[0037] 4) The fiber optic current sensor harmonic superposition test system provided by this invention has a measurement bandwidth of ≤50kHz, which can solve the current problem of harmonic measurement ≤1200Hz.

[0038] 5) The fiber optic current sensor harmonic superposition test system provided by the present invention has a pre-fabricated fiber optic coil, which can selectively configure the measurement according to the rated current, and has a large dynamic range and high accuracy, thus solving the problem of fixed rated current testing. Attached Figure Description

[0039] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0040] Figure 1 This is a structural block diagram of the fiber optic current sensor harmonic superposition test system according to an embodiment of the present invention.

[0041] Figure 2This is a schematic diagram of the current output from the current signal source in an embodiment of the present invention.

[0042] Figure 3 This is a schematic diagram of multiple optical fiber coils connected in series and wound around multiple different current-carrying wires in an embodiment of the present invention.

[0043] Figure 4 This is a schematic diagram of a single optical fiber coil being wound simultaneously on multiple current conductors in an embodiment of the present invention.

[0044] Figure 5 This is a schematic diagram of a single optical fiber coil wound on a current-carrying conductor in an embodiment of the present invention.

[0045] Figure 6 This is a schematic diagram showing the connection between the current source and the standard in an embodiment of the present invention.

[0046] Figure 7 This is a schematic diagram showing the connection of the error calculation and processing module in an embodiment of the present invention.

[0047] Figure 8 This is a schematic diagram of the fiber optic current sensor testing method according to an embodiment of the present invention. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0049] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0050] Explanation of related terms

[0051] Harmonics: When there are nonlinear (time-varying or time-invariant) loads in a power system, even if the power supply is at the power frequency of 50Hz, when the power frequency voltage or current acts on the nonlinear load, sinusoidal voltages or currents of other frequencies different from the power frequency will be generated. These sinusoidal voltages or currents of different frequencies, when expanded using Fourier series, are what people call power harmonics.

[0052] Harmonic measurement point: The location where harmonics are measured in the power grid or for users.

[0053] Fundamental component: The component with the same frequency as the power frequency obtained by performing Fourier series decomposition on a periodic alternating current.

[0054] Harmonic components: Fourier series decomposition of periodic AC quantities yields components whose frequencies are integer multiples of the fundamental frequency.

[0055] Harmonic pollution: Harmonics reduce the efficiency of electrical energy production, transmission, and utilization; cause electrical equipment to overheat, vibrate, and generate noise; and accelerate insulation aging, shortening its lifespan and even causing malfunctions or burnouts. Harmonics can cause local parallel or series resonance in the power system, amplifying the harmonic content and causing equipment such as capacitors to burn out. Harmonics can also cause malfunctions in relay protection and automatic devices, leading to confusion in electricity metering. Externally, harmonics can cause serious interference to communication and electronic equipment.

[0056] Harmonic order: The integer ratio of the harmonic frequency to the fundamental frequency.

[0057] Harmonic content (voltage or current): The value obtained by subtracting the fundamental component from a periodic alternating current quantity.

[0058] Harmonic content: The ratio of the root mean square value of the h-th harmonic component to the root mean square value of the fundamental component in a periodic alternating current (expressed as a percentage).

[0059] Total harmonic distortion rate: The root mean square value of the harmonic content in a periodic AC quantity and the root mean square value of the fundamental component (expressed as a percentage).

[0060] Harmonic source: Electrical equipment that injects harmonic current into the public power grid or generates harmonic voltage in the public power grid.

[0061] Short-time harmonics: Harmonics contained in currents with an impact duration not exceeding 2 seconds and an interval of not less than 30 seconds between two impacts, and the harmonic voltages they cause.

[0062] Fiber Optic Current Transform (FOCT) sensor.

[0063] Analog-to-digital conversion (AD) is a term used to describe the process of converting data from one another to another.

[0064] Example 1

[0065] like Figure 1 and Figure 7 As shown, Embodiment 1 of the present invention provides a fiber optic current sensor harmonic superposition testing system, comprising: a current signal source, a data acquisition module, and a data analysis waveform display module. Wherein:

[0066] The current signal source is used to output different types of current waveforms.

[0067] The data acquisition module includes an FOCT acquisition unit, a standard, a first conversion channel, a second conversion channel, a digital signal channel, and an optical fiber coil.

[0068] The data analysis waveform display module includes an error calculation and processing module, a synchronization pulse source, and a display module.

[0069] The current signal source is sequentially connected to the standard, the first conversion channel, and the error calculation and processing module. It is used to convert the output current waveform into a digital signal through the first conversion channel after passing through the standard and then transmit it to the error calculation and processing module.

[0070] The optical signal output terminal of the optical fiber coil is connected to the FOCT acquisition unit. The optical fiber coil is used to be wound on the conductor under test and send the corresponding superimposed current optical signal or single current optical signal to the FOCT acquisition unit. The FOCT acquisition unit is connected to the error calculation and processing module through the second conversion channel or digital channel.

[0071] The error calculation and processing module is used to calculate the synchronization error based on the digital signal transmitted through the first conversion channel and the output signal of the FOCT acquisition device under the synchronization of the synchronization pulse source, and to obtain the power frequency accuracy, DC accuracy, harmonic accuracy and single component waveform, which are then displayed on the display module.

[0072] As an example, the display module can be a host computer.

[0073] Specifically, conversion channels (1, 2, 3) serve as the first conversion channel, acquiring the single-supply analog signal after passing through the standard converter, performing analog-to-digital conversion, and sending the converted digital value to the error calculation and processing module. Conversion channel 4 serves as the second conversion channel, acquiring the analog output of the FOCT acquisition unit and converting it to a digital value. The digital value channel directly acquires the digital output of the FOCT acquisition unit. Either the directly output digital value from the FOCT acquisition unit or the converted digital value can be arbitrarily selected and sent to the error calculation and processing module. In the error calculation and processing module, calculations are performed based on the acquired value output by the FOCT acquisition unit and the actual value converted by the first conversion channel to obtain the power frequency accuracy, DC accuracy, harmonic accuracy, single-component waveform, and superimposed waveform, which are then displayed on the host computer.

[0074] It should be noted that the fiber optic coils involved in this solution are all pre-wound according to the rated current requirements, forming fiber optic coils with different numbers of turns. The different number of turns of the fiber optic coils is based on the different rated currents, and the fiber optic coils are wound with different numbers of turns. Specifically, fiber optic coils N1 to N9 can be pre-made, with turns of 1, 5, 10, 20, 40, 80, 100, 150, and 200, respectively.

[0075] In this scheme, the optical fiber coil is configured as follows: multiple optical fiber coils are connected in series and then wound on multiple different current conductors; or a single optical fiber coil is wound on multiple current conductors at the same time; or a single optical fiber coil is wound on a single current conductor.

[0076] like Figure 3 As shown, when the fiber optic coils are arranged in a configuration where multiple fiber optic coils are connected in series and wound around multiple different current conductors, the light source inside the FOCT collector is connected to the first optical signal terminal of the series-connected fiber optic coils via polarization-maintaining fiber optic patch cords, quarter-wave plates, and single-mode fiber optic patch cords. The second optical signal terminal of the series-connected fiber optic coils is connected to a reflector. Specifically, when multiple fiber optic coils are connected in series, the first fiber optic coil is connected to the quarter-wave plate via a fiber optic patch cord flange adapter box, the last fiber optic coil is connected to the reflector via a fiber optic patch cord flange adapter box, and the middle fiber optic coils are connected in series with the first and last fiber optic coils within the fiber optic patch cord flange adapter box.

[0077] As an example of the above embodiments, in one scheme of this embodiment, three optical fiber coils are selected for testing. The optical fiber coils N1 to N3 are connected in series, and each optical fiber coil is wound on the corresponding wire. In this scheme, the superimposed current is: I1*N1+I2*N2+I3*N3, and the superimposed current optical signal is output by sampling the single power supply current in the branch circuit.

[0078] like Figure 4 As shown, when a single fiber optic coil is simultaneously wound on multiple current conductors, the light source in the FOCT collector is connected to the first optical signal end of the single fiber optic coil via a polarization-maintaining fiber jumper, a quarter-wave plate, and a single-mode fiber jumper in sequence, and the second optical signal end of the single fiber optic coil is connected to a reflector.

[0079] As an example of the above embodiments, in one scheme of this embodiment, a single optical fiber coil is selected for testing. The optical fiber coil N4 is simultaneously wound on three conductors. In this scheme, the superimposed current is determined by the maximum value of the rated output current among the single power supplies I1, I2, and I3. The superimposed current is I1*N4, I2*N4, or I3*N4, and the output superimposed current optical signal is directly acquired.

[0080] like Figure 5 As shown, when a single fiber optic coil is wound on a current conductor, the light source in the FOCT collector is connected to the first optical signal end of the single fiber optic coil in sequence through a polarization-maintaining fiber jumper, a quarter-wave plate, and a single-mode fiber jumper. The second optical signal end of the single fiber optic coil is connected to a reflector.

[0081] As an example of the above embodiments, in one scheme of this embodiment, a single optical fiber coil is selected for testing. The optical fiber coil N1 or other optical fiber coils are only wound on a single conductor. In this scheme, the single power supply current is I3*N3, and the single power supply current signal can be measured in separate circuits.

[0082] like Figure 2 As shown, the current signal source can include various types of current sources to output different types of current waveforms, such as direct current, alternating current, harmonic current, or other special current waveforms. Specifically, it outputs at least two of the following: direct current, alternating current, and harmonic current.

[0083] As a specific example, the current signal source includes current source I1, current source I2 and current source I3. Current source I1 can output DC current, current source I2 can output AC current, and current source I3 can output DC current harmonic current or other special current waveforms.

[0084] like Figure 6 As shown, the standard is connected in series between the current source and the first conversion channel to perform current conversion on the current output by the current source. When the current signal source output current is ≤120A, it is directly connected to the standard; when the current source output current is >120A, it is connected to the standard after current conversion.

[0085] As a specific example of the above embodiment, the standard is a high-precision resistor.

[0086] Example 2

[0087] Based on the same inventive concept as the above embodiments, Embodiment 2 of the present invention provides a method for testing harmonic superposition of fiber optic current sensors.

[0088] like Figure 8 As shown, a method for testing harmonic superposition using an optical fiber current sensor includes the following steps:

[0089] S1. The current signal source outputs different types of current waveforms, which are then transmitted to the first conversion channel after passing through a standard. Specifically, the current signal source outputs different types of current waveforms through various types of current sources, such as DC current, AC current, harmonic current, or other special current waveforms.

[0090] S2. The first conversion channel converts the actual value of the single-current waveform into a digital value and sends it to the error calculation and processing module. The actual value is collected here to determine the measurement performance of the fiber optic current transformer under test in subsequent calculations.

[0091] S3. The fiber optic coil sends a superimposed current optical signal or a single current optical signal to the FOCT collector. The FOCT collector transmits the digital quantity corresponding to the superimposed current optical signal or the single current optical signal to the error calculation and processing module through the second conversion channel or digital quantity channel.

[0092] S4. Under the synchronization of the synchronization pulse source, the error calculation and processing module performs synchronization error calculation based on the digital signal transmitted by the first conversion channel and the output signal of the FOCT collector, and obtains the power frequency accuracy, DC accuracy, harmonic accuracy, single component waveform, and superimposed waveform, which are then displayed on the display module.

[0093] It should be noted that in this solution, the FOCT acquisition unit can output 0-10V analog and digital signals, and the analog and digital channels can be flexibly selected for testing.

[0094] Example 3

[0095] Based on the same inventive concept as the above embodiments, Embodiment 3 of the present invention provides a harmonic current superposition measurement system, including:

[0096] The data acquisition module includes an FOCT acquisition unit, a second conversion channel, a digital channel, and an optical fiber coil;

[0097] The data analysis waveform display module includes an error calculation and processing module and a display module;

[0098] The optical signal output terminal of the fiber optic coil is connected to the FOCT acquisition unit. The fiber optic coil is used to be wound on the conductor under test and send the corresponding optical signal to the FOCT acquisition unit. The FOCT acquisition unit is connected to the error calculation and processing module through the second conversion channel or the digital signal channel. The fiber optic coil is configured in the following ways: multiple fiber optic coils are connected in series and wound on multiple different current conductors; or a single fiber optic coil is wound on multiple current conductors at the same time; or a single fiber optic coil is wound on a single current conductor.

[0099] The error calculation and processing module is used to calculate the output signal of the FOCT acquisition unit to obtain a single current waveform or a superimposed current waveform, and display it on the display module.

[0100] Existing harmonic measurement technologies can only perform single-power-source harmonic measurements. The fiber optic current sensor harmonic superposition measurement system provided by this invention can realize the superposition measurement of power frequency superimposed harmonics, DC superimposed harmonics, and multiple harmonic currents by utilizing an optical measurement system.

[0101] Example 4

[0102] Based on the same inventive concept as the above embodiments, Embodiment 4 of the present invention provides a storage medium. The present invention can implement all or part of the processes in the methods of the above embodiments, or it can be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, and a read-only memory (ROM).

[0103] The present invention has been described above with reference to a few embodiments. However, as will be known to those skilled in the art, and as defined in the appended claims, other embodiments disclosed above are equally within the scope of the present invention.

[0104] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to “a / the / the [device, component, etc.]” ​​are openly interpreted as at least one instance of said device, component, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed unless explicitly stated otherwise.

[0105] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0106] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1A device that provides the functions specified in one or more boxes.

[0107] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0108] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A fiber optic current sensor harmonic superposition testing system, characterized in that, include: A current signal source, used to output different types of current waveforms; The data acquisition module includes an FOCT acquisition unit, a standard, a first conversion channel, a second conversion channel, a digital channel, and various fiber optic coils with different numbers of turns pre-wound according to different rated current requirements. The data analysis waveform display module includes an error calculation and processing module, a synchronization pulse source, and a display module; The current signal source is sequentially connected to the standard, the first conversion channel, and the error calculation and processing module. It is used to convert the output current waveform into a digital signal through the first conversion channel after passing through the standard and then transmit it to the error calculation and processing module. The optical signal output terminal of the optical fiber coil is connected to the FOCT acquisition unit. The optical fiber coil is used to be wound on the conductor under test and send the corresponding superimposed current optical signal or single current optical signal to the FOCT acquisition unit. The FOCT acquisition unit is connected to the error calculation and processing module through the second conversion channel or digital channel. The error calculation and processing module is used to calculate the synchronization error based on the digital signal transmitted through the first conversion channel and the output signal of the FOCT collector under the synchronization of the synchronization pulse source, and to obtain the power frequency accuracy, DC accuracy, harmonic accuracy, single component waveform, and superimposed waveform, which are then displayed on the display module. The optical fiber coils are configured such that multiple optical fiber coils are connected in series and then wound around multiple different current conductors. Alternatively, a single fiber optic coil may be wound on multiple current conductors simultaneously; or a single fiber optic coil may be wound on a single current conductor. When the optical fiber coils are configured such that multiple optical fiber coils are connected in series and wound on multiple different current conductors, the light source in the FOCT collector is connected to the first optical signal end of the series optical fiber coils in sequence through polarization-maintaining fiber jumpers, quarter-wave plates, and single-mode fiber jumpers, and the second optical signal end of the series optical fiber coils is connected to the reflector. When multiple fiber optic coils are connected in series, the first fiber optic coil is connected to a quarter-wave plate through a fiber optic patch cord flange adapter box, the last fiber optic coil is connected to a reflector through a fiber optic patch cord flange adapter box, and the middle fiber optic coil is connected in series with the first and last fiber optic coils in the fiber optic patch cord flange adapter box. When a single fiber optic coil is simultaneously wound on multiple current conductors, the light source in the FOCT collector is connected to the first optical signal end of the single fiber optic coil via a polarization-maintaining fiber jumper, a quarter-wave plate, and a single-mode fiber jumper in sequence, and the second optical signal end of the single fiber optic coil is connected to a reflector. When a single fiber optic coil is wound on a current conductor, the light source in the FOCT collector is connected to the first optical signal end of the single fiber optic coil in sequence through a polarization-maintaining fiber optic patch cord, a quarter-wave plate, and a single-mode fiber optic patch cord. The second optical signal end of the single fiber optic coil is connected to a reflector.

2. The fiber optic current sensor harmonic superposition testing system according to claim 1, characterized in that, The current signal source includes various types of current sources, and outputs at least two of the following: DC current, AC current, and harmonic current.

3. The fiber optic current sensor harmonic superposition testing system according to claim 1, characterized in that, When the current source output current is ≤120A, it is directly connected to the standard; when the current source output current is >120A, it is connected to the standard after current conversion.

4. A method for testing harmonic superposition in an optical fiber current sensor, based on the optical fiber current sensor harmonic superposition testing system according to any one of claims 1 to 3, characterized in that, Includes the following steps: Different types of current waveforms output by the current signal source are transmitted to the first conversion channel after passing through a standard; The first conversion channel converts the actual value of the current waveform of a single current into a digital value and sends it to the error calculation and processing module; The fiber optic coil sends a superimposed current optical signal or a single current optical signal to the FOCT collector. The FOCT collector then transmits the digital quantity corresponding to the superimposed current optical signal or the single current optical signal to the error calculation and processing module through the second conversion channel or digital quantity channel. Under the synchronization of the synchronous pulse source, the error calculation and processing module performs synchronization error calculation based on the digital signal transmitted by the first conversion channel and the output signal of the FOCT collector, and obtains the single component waveforms of power frequency accuracy, DC accuracy, and harmonic accuracy, as well as the superimposed current waveform, which are then displayed on the display module.

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