Broadband differential signal testing method and system

Abstract

The invention discloses a broadband differential signal testing method and system, and belongs to the technical field of AC voltage testing. The method comprises the following steps: extracting a differential signal between a standard mutual inductor and a detected mutual inductor through a precision resistance voltage divider; the differential signal is received through a detection winding, and after the differential signal is received, the detection winding induces magnetic flux change in an iron core structure to generate induced electromotive force; an electronic compensation circuit amplifies the induced electromotive force to correct the error of the differential signal, and outputs a differential signal; and receiving the differential signal through an operational amplifier so as to test the differential signal. According to the invention, not only is the error problem of a traditional isolation mutual inductor under a low differential pressure condition solved, but also the measurement precision of differential pressure signals and the reliability of data transmission in a broadband range are remarkably improved, and a powerful guarantee is provided for stable operation of a novel power system.

Description

Technical Field

[0001] This invention relates to the field of AC voltage testing technology, and more specifically, to a wideband differential signal testing method and system. Background Technology

[0002] With the development of new power systems and the large-scale integration of various power electronic devices and distributed energy sources into the power grid, power quality issues are becoming increasingly prominent. Voltage signals are affected by various factors such as harmonics, interharmonics, and transient impacts during power grid operation, exhibiting new characteristics such as wide frequency spectrum and rapid dynamic changes. Traditional voltage measurement methods are mostly centered on the power frequency, focusing on the measurement of the fundamental frequency and low-order harmonics. Their response capability to high-frequency harmonics and wideband signals is limited, making it difficult to meet the current power grid's demand for high-precision, wideband voltage measurement.

[0003] In practical applications, accurate assessment of voltage measurement errors is crucial for power quality analysis, relay protection, fault diagnosis, and equipment health monitoring. However, existing measurement systems often suffer from uneven amplitude response, inconsistent phase delay, and insufficient anti-interference capabilities over a wide frequency range, affecting the accuracy and reliability of measurement results. Especially in complex power grid environments with high penetration of new energy sources and flexible interconnection, the frequency domain components of voltage signals are richer, making traditional error measurement methods inadequate.

[0004] Currently, research on broadband voltage measurement is gradually unfolding both domestically and internationally, and related standards and testing methods are constantly being improved. However, existing technologies mostly rely on calibration and measurement of single frequency points or narrowband signals, lacking systematic analysis and compensation for errors over a wide bandwidth. While some methods can achieve error measurement within a certain range, they still have shortcomings in terms of signal bandwidth, measurement accuracy, and real-time performance, making it difficult to meet the actual needs of new power systems for high-precision voltage signal measurement across multiple frequency bands and scenarios. Summary of the Invention

[0005] Based on the above problems, there is an urgent need in this technical field for a voltage error measurement method and system that can cover a wide bandwidth and possess high precision and high real-time performance, in order to improve the measurement technology level of power systems and ensure the safe and stable operation of the power grid. This has important practical significance and application value for promoting the healthy development of new power systems such as smart grids and the energy internet. Therefore, this invention proposes a wideband differential signal testing method, including:

[0006] The differential signal between the standard current transformer and the current transformer under test is extracted using a precision resistance voltage divider.

[0007] The differential signal is received by the detection winding. After receiving the differential signal, the differential signal affects the change of magnetic flux in the core structure of the detection winding, and an induced electromotive force is generated by the change of magnetic flux in the core structure of the detection winding.

[0008] The induced electromotive force is amplified by an electronic compensation circuit, and the amplified induced electromotive force is used to correct the error of the differential signal output by the detection winding. The corrected output differential signal is then output as a micro-differential signal.

[0009] The differential signal is received by an operational amplifier to test the differential signal.

[0010] Furthermore, this invention proposes a wideband differential signal testing system, comprising:

[0011] The differential pressure extraction module extracts the differential signal between the standard current transformer and the current transformer under test through a precision resistance voltage divider.

[0012] The isolation conversion module receives the differential signal through the detection winding. After receiving the differential signal, it affects the change of magnetic flux in the sensing core structure of the detection winding through the differential signal, and generates an induced electromotive force through the change of magnetic flux in the sensing core structure of the detection winding. The induced electromotive force is amplified by the electronic compensation circuit, and the error of the differential signal output by the detection winding is corrected by the amplified induced electromotive force. The corrected output differential signal is output as a micro differential signal.

[0013] The signal amplification module receives the differential signal through an operational amplifier to test the differential signal.

[0014] Optionally, the input terminals of the precision resistance voltage divider are connected to the secondary output terminals of the standard current transformer and the current transformer under test respectively via shielded cables, and the shielding layer is grounded to suppress external electromagnetic interference.

[0015] Optionally, the precision resistive voltage divider is made of low-temperature drift metal film resistors with a temperature coefficient of ±5ppm / ℃ and calibrated resistance values.

[0016] Optionally, the output of the differential pressure extraction module and the input of the signal amplification module can be directly electrically connected via wires.

[0017] Optionally, the input of the isolation conversion module is connected in parallel with the output of the differential pressure extraction module, and the output is connected in series with the input of the signal amplification module.

[0018] Optionally, the input terminal of the signal amplification module is connected to the output terminal of the differential pressure extraction module via a wire, and the output terminal is connected to the analog-to-digital conversion interface of the external data processing unit via a differential transmission line.

[0019] Optionally, the input impedance of the signal amplification module can be matched with the output impedance of the differential pressure extraction module.

[0020] Optionally, the voltage division ratio of the precision resistor voltage divider is determined by the resistance ratio of the two precision resistors, and the error of the voltage division ratio is controlled within a very small range by selecting resistors made of low-temperature drift and high-stability materials.

[0021] Optionally, the formula for calculating the induced electromotive force of the detection winding is as follows:

[0022]

[0023] in, To induce electromotive force. N1 is the primary excitation current, N2 is the primary winding of the current sensing section, l is the magnetic circuit length, S is the cross-sectional area of ​​the iron core, μ0 is the free permeability, and μ r is the relative permeability.

[0024] Optionally, the calculation formula for the differential signal extracted by the differential pressure extraction module is as follows:

[0025]

[0026] in, To induce electromotive force. For R o2 The error between the standard value and the standard value This is the error in the voltage divider section. δ is the gain error of the instrumentation amplifier, γ is the error between R5 and the standard value, γ is the error between R4 and the standard value, and ε is the steady-state error between I2′ and I1.

[0027] In another aspect, the present invention also provides a computing device, comprising: one or more processors;

[0028] A processor is used to execute one or more programs;

[0029] When the one or more programs are executed by the one or more processors, the method described above is implemented.

[0030] In another aspect, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the method described above.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention provides a broadband differential signal testing method, comprising: extracting the differential signal between a standard current transformer and the current transformer under test using a precision resistive voltage divider; receiving the differential signal through a detection winding, and after receiving the differential signal, influencing the magnetic flux change in the induction core structure of the detection winding through the differential signal, thereby generating an induced electromotive force (EMF); amplifying the induced EMF using an electronic compensation circuit, correcting the error of the differential signal output by the detection winding using the amplified induced EMF, and outputting the corrected differential signal as a differential signal; and receiving the differential signal through an operational amplifier to test the differential signal. The implementation of this invention not only solves the error problem of traditional isolation current transformers under low differential pressure conditions, but also significantly improves the measurement accuracy and data transmission reliability of differential pressure signals over a wide bandwidth, providing a strong guarantee for the stable operation of new power systems. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method of the present invention;

[0034] Figure 2 This is a schematic diagram of the system of the present invention;

[0035] Among them, 1 is the differential pressure extraction module, 2 is the isolation conversion module, and 3 is the signal amplification module. Detailed Implementation

[0036] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0037] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0038] Example 1:

[0039] This invention proposes a wideband differential signal testing method, such as... Figure 1 As shown, it includes:

[0040] Step 1: Extract the differential signal between the standard current transformer and the current transformer under test using a precision resistance voltage divider;

[0041] Step 2: Receive the differential signal through the detection winding. After receiving the differential signal, influence the change of magnetic flux in the core structure of the detection winding through the differential signal, and generate an induced electromotive force through the change of magnetic flux in the core structure of the detection winding.

[0042] Step 3: The induced electromotive force is amplified by the electronic compensation circuit, and the error of the differential signal output by the detection winding is corrected by the amplified induced electromotive force. The corrected output differential signal is then output as a micro differential signal.

[0043] Step 4: Receive the differential signal through an operational amplifier to test the differential signal.

[0044] This invention solves the error problem of traditional isolation transformers under low differential pressure conditions by introducing a precision resistor voltage divider circuit and an electronically compensated current transformer, while also achieving linear extraction of differential pressure signals over a wide frequency band. The design of the signal amplification module ensures that the amplitude range of the differential pressure signal is compatible with subsequent processing stages.

[0045] To further improve the system's stability and reliability, the precision resistive voltage divider circuit of the differential pressure extraction module uses low-temperature drift metal film resistors with a temperature coefficient controlled within ±5ppm / ℃, and the resistance values ​​are rigorously calibrated to reduce errors. In the differential signal acquisition stage, the secondary output terminals of the standard current transformer and the current transformer under test are directly connected to the input terminal of the voltage divider circuit via shielded cables, with the shielding layer grounded to suppress external electromagnetic interference. The electronic compensation circuit in the isolation conversion module is built using a high-speed operational amplifier, and a proportional-integral controller is introduced into the feedback path to quickly respond to changes in excitation current and dynamically compensate for errors.

[0046] The instrumentation amplifier in the signal amplification module adopts a three-op-amp architecture. The input stage uses a low-noise, high common-mode rejection ratio operational amplifier, the intermediate stage uses a resistor network to set a fixed gain, and the output stage uses a low-pass filter to suppress high-frequency noise. The input impedance of this module is matched with the output impedance of the differential pressure extraction module to avoid signal distortion caused by impedance mismatch.

[0047] In summary, this invention constructs a complete broadband micro-differential signal testing system by introducing a differential pressure extraction module, an isolation conversion module, and a signal amplification module. The modules work collaboratively through clear connections and technical means, not only solving the error problem of traditional isolation transformers under low differential pressure conditions, but also significantly improving the measurement accuracy of differential pressure signals and the reliability of data transmission over a wide bandwidth, providing strong support for the stable operation of new power systems.

[0048] Example 2:

[0049] This invention proposes a wideband differential signal testing system, such as... Figure 2 As shown, it includes:

[0050] Differential pressure extraction module 1, isolation conversion module 2, and signal amplification module 3. The specific implementation methods of each module will be described in detail below with reference to the accompanying drawings. A wideband voltage differential signal testing method is used to extract the differential voltage signal from a standard current transformer U. N and the current transformer under test U x The differential pressure signal ΔU between the two voltage levels is amplified by a fixed gain G before being output. Traditional differential transformer calibration devices use isolation transformers to extract the differential pressure signal and achieve electrical isolation between high and low voltage equipment. However, when the accuracy of the transformer under test is high, the differential pressure amplitude across the primary winding of the isolation transformer is extremely small, and the isolation transformer operates at a low working magnetic flux density, which will introduce errors into the output results.

[0051] The differential pressure extraction module 1 employs a precision resistor voltage divider circuit structure. Its input terminals are connected to the secondary output terminals of the standard current transformer and the current transformer under test via shielded cables. The shielding layer is grounded to suppress external electromagnetic interference. The precision resistor voltage divider circuit consists of low-temperature drift metal film resistors with a temperature coefficient controlled within ±5ppm / ℃, and the resistance values ​​are rigorously calibrated to minimize errors. The output terminal of the differential pressure extraction module 1 is directly connected to the input terminal of the signal amplification module 3 via wires for electrical connection. The function of the differential pressure extraction module 1 is to acquire the differential pressure signal from the secondary output terminals of the standard current transformer and the current transformer under test, and transmit it to subsequent modules for processing.

[0052] The isolation conversion module 2 is designed based on an electronically compensated current transformer. Its input is connected in parallel with the output of the differential pressure extraction module 1, and its output is connected in series with the input of the signal amplification module 3. Internally, the isolation conversion module 2 includes a detection winding and a compensation circuit. The induced electromotive force in the detection winding drives the compensation circuit through a feedback path built with a high-speed operational amplifier. A proportional-integral controller is introduced into the feedback path to quickly respond to changes in the excitation current and dynamically compensate for errors. The design of the isolation conversion module 2 ensures high-precision extraction of the differential pressure signal under low differential pressure conditions, while avoiding the errors introduced by the excitation current in traditional isolation transformers.

[0053] The signal amplification module 3 consists of an instrumentation amplifier. Its input is connected to the output of the differential pressure extraction module 1 via a wire, and its output is connected to the analog-to-digital conversion interface of the data processing unit 4 via a differential transmission line. The instrumentation amplifier adopts a three-operation amplifier architecture. The input stage uses a low-noise, high common-mode rejection ratio operational amplifier, the intermediate stage uses a resistor network to set a fixed gain, and the output stage uses a low-pass filter to suppress high-frequency noise. The input impedance of the signal amplification module 3 is matched with the output impedance of the differential pressure extraction module 1 to avoid signal distortion caused by impedance mismatch. The signal amplification module 3 amplifies the differential pressure signal to an amplitude range suitable for subsequent processing stages and transmits the amplified signal to the data processing unit 4 via a differential transmission line.

[0054] The differential resistor divider has its two ends corresponding to the secondary output signals of the standard current transformer and the voltage transformer under test, respectively. In the isolation conversion stage, the induced electromotive force in the core of the N3 winding is detected and the electronic circuit is driven to compensate for the error introduced by the excitation current, thus reducing the excitation error of the current transformer. The impedances of the primary winding N1 and the secondary winding N2 of the current transformer are Z1 = r1 + jωL1 and Z2 = r2 + jωL2, respectively. The error of the differential pressure signal extraction unit is now analyzed:

[0055] Assume the voltage divider error is... The gain error of the instrumentation amplifier is The voltage after output through A1 for:

[0056]

[0057] Let the primary current of winding N1 be Induced electromotive force is The potential balance equation is:

[0058]

[0059] Right now:

[0060]

[0061] in For standard resistor R o1 The error between the value and the rated value.

[0062] Let the secondary output current be The primary excitation current is The magnetic potential balance equations within the main iron core are:

[0063]

[0064] For the secondary side of the current transformer, the potential balance equation can be used to obtain:

[0065]

[0066] in Where G is the gain amplification factor of the compensation unit.

[0067] For the output voltage of the detection winding According to Faraday's law of electromagnetic induction:

[0068]

[0069] According to Ampere's circuital law, we can obtain:

[0070]

[0071] In the above formula, ∑i is Therefore:

[0072]

[0073] Where l is the magnetic circuit length of the CT core. From equations (4.23) and (4.25), we can obtain:

[0074]

[0075] Similarly, we have:

[0076]

[0077] The simultaneous equations yield:

[0078]

[0079] For the final output U2 of the current transformer, we have:

[0080]

[0081] in For R o2 The error between the value and the standard value.

[0082] Assume the primary and secondary windings have the same number of turns, i.e., N1 = N2. Then, the calculation can be performed using the diagram. and steady-state error between for:

[0083]

[0084] Therefore, the output voltage of the differential pressure signal extraction unit can be expressed as:

[0085]

[0086] The aforementioned modules work collaboratively through clearly defined connections and technical means to construct a complete broadband differential signal testing system. Differential pressure extraction module 1 acquires differential pressure signals from the secondary outputs of both the standard instrument transformer and the instrument transformer under test. Isolation conversion module 2 eliminates errors introduced by excitation current through an electronically compensated current transformer design. Signal amplification module 3 amplifies the differential pressure signal to an amplitude range suitable for subsequent processing stages. The connections and coordination between these modules ensure high-precision extraction and processing of differential pressure signals over a wide bandwidth, while simultaneously resolving the error problem of traditional isolation transformers under low differential pressure conditions, providing strong support for the stable operation of new power systems.

[0087] Example 3:

[0088] Based on the same inventive concept, this invention also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions from the computer storage medium to implement corresponding method flows or corresponding functions, thereby implementing the steps of the methods in the above embodiments.

[0089] Example 4:

[0090] Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiments.

[0091] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented 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. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0092] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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 illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0093] 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.

[0094] 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.

[0095] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0096] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for testing wideband differential signals, characterized in that, include: The differential signal between the standard current transformer and the current transformer under test is extracted using a precision resistance voltage divider. The differential signal is received by the detection winding. After receiving the differential signal, the differential signal affects the change of magnetic flux in the core structure of the detection winding, and an induced electromotive force is generated by the change of magnetic flux in the core structure of the detection winding. The induced electromotive force is amplified by an electronic compensation circuit, and the error of the differential signal output by the detection winding is corrected by the amplified induced electromotive force. The corrected output differential signal is then output as a micro-differential signal. The differential signal is received by an operational amplifier to test the differential signal.

2. A wideband differential signal testing system, characterized in that, include: The differential pressure extraction module extracts the differential signal between the standard current transformer and the current transformer under test through a precision resistance voltage divider. The isolation conversion module receives the differential signal through the detection winding. After receiving the differential signal, it affects the change of magnetic flux in the sensing core structure of the detection winding through the differential signal, and generates an induced electromotive force through the change of magnetic flux in the sensing core structure of the detection winding. The induced electromotive force is amplified by the electronic compensation circuit, and the error of the differential signal output by the detection winding is corrected by the amplified induced electromotive force. The corrected output differential signal is output as a micro differential signal. The signal amplification module receives the differential signal through an operational amplifier to test the differential signal.

3. The wideband differential signal testing system according to claim 2, characterized in that, The input terminal of the precision resistor voltage divider is connected to the secondary output terminals of the standard current transformer and the current transformer under test respectively via shielded cables, and the shielding layer is grounded to suppress external electromagnetic interference.

4. The wideband differential signal testing system according to claim 2, characterized in that, The precision resistive voltage divider is composed of a low-temperature drift metal film resistor with a temperature coefficient of ±5ppm / ℃, and the resistance value has been calibrated.

5. The wideband differential signal testing system according to claim 2, characterized in that, The output terminal of the differential pressure extraction module and the input terminal of the signal amplification module are directly electrically connected by a wire.

6. The wideband differential signal testing system according to claim 2, characterized in that, The input terminal of the isolation conversion module is connected in parallel with the output terminal of the differential pressure extraction module, and the output terminal is connected in series with the input terminal of the signal amplification module.

7. The wideband differential signal testing system according to claim 2, characterized in that, The input terminal of the signal amplification module is connected to the output terminal of the differential pressure extraction module via a wire, and the output terminal is connected to the analog-to-digital conversion interface of the external data processing unit via a differential transmission line.

8. The wideband differential signal testing system according to claim 2, characterized in that, The input impedance of the signal amplification module is matched with the output impedance of the differential pressure extraction module.

9. The wideband differential signal testing system according to claim 2, characterized in that, The voltage division ratio of the precision resistor voltage divider is determined by the resistance ratio of the two precision resistors, and the error of the voltage division ratio is controlled within a very small range by selecting resistors made of low-temperature drift and high-stability materials.

10. The wideband differential signal testing system according to claim 2, characterized in that, The formula for calculating the induced electromotive force of the detection winding is as follows: in, To induce electromotive force. N1 is the primary excitation current, N2 is the primary winding of the current sensing section, l is the magnetic circuit length, S is the cross-sectional area of ​​the iron core, μ0 is the free permeability, and μ r is the relative permeability.

11. The wideband differential signal testing system according to claim 2, characterized in that, The calculation formula for the differential signal extracted by the differential pressure extraction module is as follows: in, To induce electromotive force. For R o2 The error between the standard value and the standard value This is the error in the voltage divider section. δ is the gain error of the instrumentation amplifier, γ is the error between R5 and the standard value, γ is the error between R4 and the standard value, and ε is the steady-state error between I2′ and I1.

12. The wideband differential signal testing system according to claim 2, characterized in that, The precision resistor voltage divider is encapsulated within a shielding layer, which is grounded.

13. A computer device, characterized in that, include: One or more processors; A processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the method of claim 1 is implemented.

14. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the method as described in claim 1.

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