Current measurement method and apparatus

Abstract

The application relates to a current measurement method and device, obtaining a first scale value and a second scale value, a first processing module collects a current signal of a load to obtain the first scale value, a second processing module collects the current signal of the load to obtain the second scale value, the first scale value is smaller than the second scale value; obtaining a first rated value of the first processing module and a second rated value of the second processing module, the first rated value is larger than the second rated value; obtaining a first named value of the first processing module from the first scale value and the first rated value, obtaining a second named value of the second processing module from the second scale value and the second rated value; determining a target processing module in the first processing module and the second processing module according to a preset multiple between the first scale value and the second scale value, the first named value and the second named value, the target processing module collects a measurement current value of the current for the load, and the problem that the measurement range and the precision requirement under multiple operation conditions cannot be simultaneously met during current measurement is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current measurement, in particular to a current measurement method and device. BACKGROUND

[0002] The all-fiber current measurement device has small volume and light weight, simple insulation structure, good frequency characteristics and transient characteristics, fast step response, and large dynamic range, and has no problems such as magnetic saturation, ferromagnetic resonance, and secondary open circuit. The primary end of the all-fiber current measurement device is passive, so it has strong anti-interference ability, is safe, green and environmentally friendly, and is easy to digitize. Therefore, the all-fiber current measurement device can meet the needs of the power system. In recent years, with the rapid development of smart substations and flexible DC transmission technology, the all-fiber current measurement device has been widely used, and the performance index requirements for the all-fiber current measurement device are also getting higher and higher. Among them, the measurement accuracy and the maximum measurement range are two important indexes of the measurement device.

[0003] When applied in actual engineering, the all-fiber current measurement device under different operating conditions has different index requirements for the same measurement point. For example: in a bipolar configuration DC transmission system, when single-pole ground operation or bipolar unbalanced operation is performed, the rated value of the ground pole line current can reach thousands of amperes; when bipolar balanced operation is performed, the ground pole line current can be even less than ten amperes. For example: for the flexible DC charging loop current measurement point, the current when charging the converter with resistance is between tens of amperes and a few amperes, and when the bypass switch is closed for normal operation after charging is completed, the loop current can reach thousands of amperes.

[0004] At present, the maximum measurement range of the measurement device is fixed. If small currents can be measured with high precision, the measurement range of the device is small; if the measurement range of the device is large, small currents cannot be measured with high precision, and different performance requirements for current measurement under different operating conditions cannot be met at the same time, and there is a problem that the measurement range and precision requirements under multiple operating conditions cannot be met at the same time when measuring current. SUMMARY

[0005] Therefore, it is necessary to provide a current measurement method and device that can solve the problem that the measurement range and precision requirements under multiple operating conditions cannot be met at the same time when measuring current.

[0006] In a first aspect, the present application provides a current measurement method, comprising:

[0007] obtaining a first scale value and a second scale value, wherein the first scale value is obtained by a first processing module collecting a current signal of a load, the second scale value is obtained by a second processing module collecting the current signal of the load, and the first scale value is less than the second scale value;

[0008] Obtain the first rated value of the first processing module and the second rated value of the second processing module, wherein the first rated value is greater than the second rated value;

[0009] Based on the first scale value and the first rated value, the first named value of the first processing module is obtained, and based on the second scale value and the second rated value, the second named value of the second processing module is obtained.

[0010] Obtain a preset multiple between the first scale value and the second scale value. Based on the preset multiple, the first scale value, and the second scale value, determine a target processing module in the first processing module and the second processing module. Use the current collected by the target processing module as the measured current value of the load.

[0011] In one embodiment, obtaining a preset multiple between the first scale value and the second scale value includes:

[0012] Obtain a first preset scale value corresponding to the first rated value, and obtain a second preset scale value corresponding to the second rated value, wherein the first preset scale value is less than the second preset scale value;

[0013] The preset multiple is obtained by the ratio of the first preset scale value and the second preset scale value.

[0014] In one embodiment, determining a target processing module in the first processing module and the second processing module based on the preset multiple, the first named value, and the second named value includes:

[0015] Multiply the first named value by the preset multiple to obtain the product;

[0016] The product and the second named value are compared, and the target processing module is determined based on the comparison result.

[0017] In one embodiment, the target processing module is determined based on the comparison results, including:

[0018] If the product is greater than or equal to the second named value, the first processing module is determined to be the target processing module;

[0019] If the product is less than the second named value, the second processing module is determined to be the target processing module.

[0020] In one embodiment, determining a target processing module in the first processing module and the second processing module based on the preset multiple, the first named value, and the second named value includes:

[0021] When it is determined that the first processing module is the target processing module, the time slot resources are allocated to the first processing module;

[0022] When the second processing module is determined to be the target processing module, the time slot resources are allocated to the second processing module.

[0023] Secondly, this application also provides a current measuring device, comprising: a control module, a first processing module, and a second processing module, wherein the control module is connected to both the first processing module and the second processing module; wherein...

[0024] The first processing module is used to acquire the current signal of the load and obtain a first scale value based on the current signal;

[0025] The second processing module is used to acquire the current signal and obtain a second scale value based on the current signal;

[0026] The control module can implement the current measurement method according to any one of claims 1-5.

[0027] In one embodiment, the first processing module includes:

[0028] A first acquisition unit is connected to the load. The first acquisition unit acquires the current signal of the load according to a first acquisition frequency, wherein the first acquisition frequency is the intrinsic frequency of the load.

[0029] In one embodiment, the first processing module further includes:

[0030] A first driving unit, connected to the load, is used to drive the light source of the load;

[0031] A first signal generating unit, connected to the load, is used to drive the phase modulator of the load.

[0032] In one embodiment, the second processing module further includes:

[0033] A second acquisition unit is connected to the load. The second acquisition unit acquires the current signal output by the load according to a second acquisition frequency, wherein the second acquisition frequency is greater than the intrinsic frequency of the load.

[0034] In one embodiment, the second processing module further includes:

[0035] A second driving unit, connected to the load, is used to drive the light source of the load;

[0036] A second signal generating unit, connected to the load, is used to drive the phase modulator of the load.

[0037] The aforementioned current measurement method and apparatus acquire a first scale value and a second scale value. The first scale value is obtained by a first processing module acquiring the current signal of the load, and the second scale value is obtained by a second processing module acquiring the current signal of the load. The first scale value is less than the second scale value. The method further acquires a first rated value of the first processing module and a second rated value of the second processing module, wherein the first rated value is greater than the second rated value. Based on the first scale value and the first rated value, a first named value of the first processing module is obtained. Based on the second scale value and the second rated value, a second named value of the second processing module is obtained. A preset multiple between the first scale value and the second scale value is acquired. Based on the preset multiple, the first named value, and the second named value, a target processing module is determined between the first and second processing modules. The current acquired by the target processing module is used as the measured current value of the load. By determining the target processing module based on the load current signal and obtaining the measured current value of the load through the target processing module, different measurement indicators under various operating conditions can be met, solving the problem that current measurement cannot simultaneously meet the measurement range and accuracy requirements under multiple operating conditions. Attached Figure Description

[0038] Figure 1 This is a schematic flowchart of a circuit measurement method in one embodiment of this application;

[0039] Figure 2 This is a structural block diagram of a circuit measurement device in one embodiment of this application;

[0040] Figure 3 This is a schematic diagram of the structure of an all-fiber current transformer in one embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0042] In one embodiment, such as Figure 1 As shown, a current measurement method is provided. This embodiment illustrates the application of this method to a terminal. It is understood that this method can also be applied to a server, and further to a system including both a terminal and a server, and implemented through interaction between the terminal and the server. In this embodiment, the method includes the following steps:

[0043] Step 101: Obtain a first scale value and a second scale value, wherein the first scale value is obtained by the first processing module acquiring the current signal of the load, and the second scale value is obtained by the second processing module acquiring the current signal of the load, and the first scale value is less than the second scale value;

[0044] In this process, the first processing module and the second processing module simultaneously acquire the load current signal. The first scale value is the per-unit value obtained by the first processing module based on the load current signal, and the second scale value is the per-unit value obtained by the second processing module based on the load current signal. Because the first processing module and the second processing module select different rated values, the scale values ​​obtained by the first processing module and the second processing module based on the same current signal are different, and the first scale value is smaller than the second scale value.

[0045] Step 102: Obtain the first rated value of the first processing module and the second rated value of the second processing module, wherein the first rated value is greater than the second rated value.

[0046] Specifically, based on the operating conditions of the load, the measurement ranges of the first processing module and the second processing module are determined. A first rated value is obtained based on the measurement range of the first processing module, where the first rated value is the nominal value corresponding to a 1.0 per-unit value in the first processing module; a second rated value is obtained based on the measurement range of the second processing module, where the second rated value is the nominal value corresponding to a 1.0 per-unit value in the second processing module.

[0047] For example, the first rated value N1 of the first processing module is 3000A, and the data corresponding to 1.0 per-unit value in the first processing module is 3862. The second rated value N2 of the second processing module is 300A, and the data corresponding to 1.0 per-unit value in the second processing module is 23173. When the current signal corresponds to a current value of 30A, in the first processing module, the first scale value P1 = 30 * 3862 / 3000 = 0.01 per-unit value; in the second processing module, the second scale value M1 = 30 * 23173 / 300 = 0.1 per-unit value.

[0048] The second processing module has a smaller measurement range and a smaller second rated value, while its second scale value is larger. Therefore, the second processing module can use a larger number of scale values ​​to record and represent small currents, thereby improving the accuracy of the current measured by the second processing module. Thus, when the magnitude of the load current signal is within the measurement range of the second processing module, for the same current value, the current measurement accuracy obtained by the second processing module is higher than that of the first processing module.

[0049] Step 103: Based on the first scale value and the first rated value, obtain the first named value of the first processing module; based on the second scale value and the second rated value, obtain the second named value of the second processing module.

[0050] The first named value is the current value measured by the first processing module, and the second named value is the current value measured by the second processing module. Optionally, the first named value of the first processing module is obtained by multiplying the first scale value by the first rated value, where the first named value = first scale value P1 * first rated value N1. Similarly, the second named value = second scale value P1 * second rated value N1.

[0051] Step 104: Obtain the preset multiple between the first scale value and the second scale value. Based on the preset multiple, the first scale value and the second scale value, determine the target processing module in the first processing module and the second processing module, and use the current collected by the target processing module as the measured current value of the load.

[0052] For current signals of the same magnitude, the first scale value is smaller than the second scale value, and the second scale value is equal to the first scale value by a preset multiple. To determine the load current magnitude using the first and second scale values, the first scale value is multiplied by the preset multiple to obtain a product, which is then compared to the second scale value. If the load current value is greater than the second rated value of the second processing module, the second processor limits the current; if the product is greater than the second scale value, the detected current value is determined to be larger, and the first processing module is selected as the target processing module. Conversely, if the current value is smaller, the second processing module is selected as the target processing module.

[0053] For example, in the first processing module, the 1.0 per-unit value corresponds to data 3862, and in the second processing module, the 1.0 per-unit value corresponds to data 23173. The preset multiple between the first and second scale values ​​is 6. If the load current value is large under the current operating condition and exceeds the measurement range of the second processing module, the product of the first scale value and the preset multiple is greater than or equal to the second scale value; if the load current value is large under the previous operating condition and is within the measurement range of the second processing module, the product of the first scale value and the preset multiple is less than the second scale value.

[0054] In the aforementioned current measurement method, the first processing module has a large measurement range, while the second processing module has a small measurement range but high accuracy. The load current varies under different operating conditions. Under lower current conditions, the load current measurement index is a high-precision small current; under higher current conditions, the load current measurement index is a large current, with lower accuracy requirements. Therefore, the first processing module can meet the needs of low-current operating conditions, while the second processing module can meet the needs of high-current operating conditions. The first and second processing modules simultaneously acquire the load current signal. Based on the rated values ​​and scale values ​​of the two processing modules, the target processing module that meets the measurement index under the current operating condition is determined, and the current acquired by the target processing module is used as the measured current value of the load. This method satisfies different measurement indexes under various operating conditions and solves the problem that current measurement cannot simultaneously meet the measurement range and accuracy requirements under multiple operating conditions.

[0055] In one embodiment, obtaining a preset multiple between a first scale value and a second scale value includes: obtaining a first preset scale value corresponding to a first rated value, obtaining a second preset scale value corresponding to a second rated value, wherein the first preset scale value is less than the second preset scale value; and obtaining the preset multiple based on the ratio of the first preset scale value and the second preset scale value.

[0056] The first preset scale value represents the first rated value, and the second preset scale value represents the second rated value. The magnitude of the first preset scale value is obtained according to the current data transmission format.

[0057] Optionally, the current data is transmitted and communicated using the FT3 format, with each data point being 16 bits long. Therefore, the maximum scale value of the second processing module is 2^15. Taking the effective current value yields 2^15 / 1.414 = 23173, which is used as the first preset scale value. Since the total length of each data point remains constant when the first and second processing modules transmit data, a smaller preset scale value is needed to represent a larger range of measured values. The first and second preset rated values ​​are determined based on the measurement range. When the measurement range of the first processing module is 6 times that of the second processing module, the first preset scale value is 6 times the second preset scale value. 23173 ÷ 3862 ≈ 6, so 3862 is used as the second preset scale value. Correspondingly, for the same current value, the first scale value read by the first processor is also 6 times the second scale value read by the second processor.

[0058] Based on a preset multiple, a first named value, and a second named value, the target processing module is determined from the first processing module and the second processing module. This includes: multiplying the first named value and the preset multiple to obtain a product; comparing the product with the second named value; and determining the target processing module based on the comparison result. Determining the target processing module based on the comparison result further includes: if the product is greater than or equal to the second named value, determining the first processing module as the target processing module; and if the product is less than the second named value, determining the second processing module as the target processing module.

[0059] As the current increases, both the first and second scale values ​​increase accordingly. When the load current is large, the second processing module's limit and the second scale value reach their maximum values. Because the first rated value is greater than the second rated value, the second processing module is unaffected and can obtain the corresponding first scale value based on the current. Therefore, when the load current is large, the product is greater than the second rated value, and the first processing module is selected as the target processing module. Conversely, when the detected load current is small, the second processing module measures the current with higher accuracy, and the second processing module is selected as the target processing module.

[0060] Optionally, the first rated value equals the first scale value P1 * the first rated value N1; the second rated value equals the second scale value M1 * the second rated value N2. The rated extended primary limit k is obtained, typically 1.2. The second rated value and the rated extended primary limit k are multiplied to obtain the maximum allowable current value of the second processing module. Based on the preset multiple, the first rated value, the second rated value, and the rated extended primary limit, a target processor is selected. When P1*N1*6 ≥ k*M1*N2, the first processing module is selected as the target processing module; when P1*N1*6 < k*M1*N2, the second processing module is selected as the target processing module.

[0061] When the first processing module is identified as the target processing module, time slot resources are allocated to the first processing module; when the second processing module is identified as the target processing module, time slot resources are allocated to the second processing module. An asynchronous time-division multiplexing strategy is used to allocate time slot resources. For example, when the detected measurement value is large, i.e., P1*N1*6 ≥ k*M1*N2, more time slot resources are allocated to the first processing module, and the measured current value P1*N1 is output; when the detected measurement value is small, i.e., P1*N1*6 < k*M1*N2, more time slot resources are allocated to the second processing module, and the measured current value M1*N2 is output.

[0062] Based on the same inventive concept, this application also provides a current measuring device for implementing the current measuring method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more current measuring device embodiments provided below can be found in the limitations of the current measuring method described above, and will not be repeated here.

[0063] In one embodiment, such as Figure 2 As shown, a current measuring device is provided, including: a control module, a first processing module, and a second processing module, wherein the control module is connected to both the first and second processing modules; wherein the first processing module is used to acquire the current signal of the load and obtain a first scale value based on the current signal; the second processing module is used to acquire the current signal and obtain a second scale value based on the current signal; the control module can implement the current measuring method in any of the above embodiments.

[0064] In one embodiment, the first processing module includes: a first acquisition unit connected to a load, the first acquisition unit acquiring a current signal of the load according to a first acquisition frequency, wherein the first acquisition frequency is the intrinsic frequency of the load. The second processing module includes: a second acquisition unit connected to the load, the second acquisition unit acquiring a current signal output by the load according to a second acquisition frequency, wherein the second acquisition frequency is greater than the intrinsic frequency of the load.

[0065] The first processor module samples at a frequency of F1kHz, where F1 is the native frequency of the load. Using this native frequency to demodulate the current signal allows for rapid tracking of current changes and the measurement of a wider current range. The second processing module samples at a frequency higher than the native frequency of the load, such as 2F1kHz. Using a higher frequency for demodulation improves the accuracy of current measurement. Optionally, when acquiring the current signal, the second acquisition unit uses multi-point sampling to average the output current, thereby filtering out noise in the sampling and further improving the measurement accuracy of small currents.

[0066] Taking an optical current transformer as the load as an example, F1 is the intrinsic frequency of the optical current transformer, and its value is 1 / (2T). T is the transit time of the optical current transformer. The transit time refers to the time required for the light emitted from the light source to return to the detector. It is equal to the optical path length divided by the speed of light in the polarization-maintaining optical cable. The speed of light is generally taken as 2*108m / s.

[0067] The first processing module further includes: a first driving unit connected to the load for driving the light source of the load; and a first signal generating unit connected to the load for driving the phase modulator of the load. The second processing module further includes: a second driving unit connected to the load for driving the light source of the load; and a second signal generating unit connected to the load for driving the phase modulator of the load.

[0068] Specifically, when the first processing module is the target processing module, more time slot resources are allocated to the first processing module, and the load is driven through the first driving unit and the first signal generating unit. When the second processing module is the target processing module, more time slot resources are allocated to the second processor, and the load is driven through the second driving unit and the second signal generating unit.

[0069] Each module in the aforementioned current measuring device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0070] In one embodiment, an all-fiber current transformer is provided. Figure 3 This is a schematic diagram of the structure of an all-fiber current transformer provided in this embodiment. The all-fiber current transformer includes a data acquisition unit 1, a transmission fiber 3, and a fiber sensing ring 2.

[0071] The measurement accuracy of an all-fiber current transformer is closely related to the Verdet constant of the fiber and the number of turns in the fiber sensing loop 2. A higher Verdet constant and a greater number of turns in the fiber loop result in higher measurement accuracy. However, all-fiber current transformers are limited by a deflection angle not exceeding 2π and a limited number of digital sampling bits. While improving test accuracy, the dynamic range of the measurement device will decrease. To simultaneously meet the requirements of accuracy and dynamic range, a suitable Verdet constant for the sensing fiber and a suitable number of turns for the fiber sensing loop 2 can be selected based on the following principles: The selection principles include: ensuring that the measurement accuracy reaches the 0.2-level metrological accuracy requirement when the measuring point current is 10%-150% of the rated current; ensuring that the measurement accuracy reaches less than 3% composite error when the measuring point current is outside the 10%-150% rated current range; and ensuring that the current output does not saturate under the dynamic current peak condition of ±6In (In being the rated current of the measuring point), thus meeting the dynamic performance requirements.

[0072] The acquisition unit 1 and the fiber optic sensing ring 2 are connected via a transmission fiber optic cable 3. The acquisition unit 1 includes a light source 10, a coupler 11, a polarizer 12, a polarization beam splitter 13, a phase modulator 14, a photodetector 15, a first signal processor, a second signal processor 17, and a third signal processor 18.

[0073] The first processing module is a first signal processor; the second processing module is a second signal processor 17; and the control module is a third signal processor 18. The first signal processor and the second signal processor 17 employ time-division multiplexing processing.

[0074] The first signal processor is connected to the electrical signal output port of the photodetector 15. The first signal processor is also connected to the drive electrical port of the light source 10. The first signal processor is also connected to the drive electrical port of the phase modulator 14. Optionally, the first signal processor further includes a drive circuit to drive the light source 10 to emit light. Optionally, the first signal processor further includes a signal generator to generate an electrical signal that drives the phase modulator 14 to operate. Optionally, the first signal processor further includes a signal demodulation circuit for demodulating the Faraday phase shift signal generated by the current in the fiber optic sensing loop from the optical signal returned from the photodetector 15.

[0075] The second signal processor 17 is connected to the electrical signal output port of the photodetector 15. The signal processor 17 is also connected to the drive electrical port of the light source 10. The signal processor 17 is also connected to the drive electrical port of the phase modulator 14. Optionally, the signal processor 17 further includes a drive circuit to drive the light source 10 to emit light. Optionally, the signal processor 17 further includes a signal generator to generate an electrical signal that drives the phase modulator 14 to operate. Optionally, the signal processor 17 further includes a signal demodulation circuit for demodulating the Faraday phase shift signal generated by the current in the fiber optic sensing loop from the optical signal returned from the photodetector 15.

[0076] In the acquisition unit 1, the first signal processor is used to demodulate the rated current (thousands of amperes) measurement data, the second signal processor 17 is used to demodulate the small current (tens of amperes) measurement data, and the third signal processor 18 performs logical judgment and switching on the two sets of data to output to the control and protection system.

[0077] Optionally, the third signal processor 18 is connected to the control and protection system, which adjusts the all-fiber current transformer based on the measured current value output by the third signal processor 18. The third signal processor 18 employs an asynchronous time-division multiplexing strategy. When the detected measured value is large, P1*N1*6 ≥ k*M1*N2, more time slot resources are allocated to the first processor, and the third signal processor 18 outputs data P1*N1 to the control and protection system. It also controls the first processor to interact with the light source 10, phase modulator 14, and photodetector 15 in the corresponding time slot through time-division multiplexing logic. When the detected measured value is small, P1*N1*6 < k*M1*N2, more time slot resources are allocated to the second processor, and the third signal processor 18 outputs data M1*N2 to the control and protection system. It also controls the first processor to interact with the light source 10, phase modulator 14, and photodetector 15 in the corresponding time slot through time-division multiplexing logic. Here, k is the rated primary limit, typically taken as 1.2.

[0078] Coupler 11 may also include at least one of beam splitter and optical circulator. The two ports on the left side of coupler 11 are the first port and the second port from top to bottom, and the two ports on the right side are the third port and the fourth port from top to bottom.

[0079] The light source 10 is connected to the first end of the coupler 11. The third end of the coupler 11 is connected to one end of the polarizer 12. The other end of the polarizer 12 is connected to one end of the polarization beam splitter 13. The other end of the polarization beam splitter 13 is connected to one end of the phase modulator 14. The other end of the phase modulator 14 is connected to the transmission optical fiber 3. The above connections include, but are not limited to, optical fiber fusion splicing.

[0080] The fiber optic sensing ring 2 includes a λ / 4 waveplate 21, a sensing fiber 22, and a reflector 23. The λ / 4 waveplate 21 is connected to the transmission fiber 3. The sensing fiber 22 is connected to the λ / 4 waveplate 21. The connection methods include, but are not limited to, fiber optic fusion splicing. The reflector 23 is located at the end of the sensing fiber 22, reflecting two orthogonally circularly polarized rays, causing them to return and propagate along the sensing fiber 22.

[0081] The second end of coupler 11 is connected to the optical port of photodetector 15, including but not limited to fiber optic splicing. The fourth end of coupler 11 can be left unused or connected to another photodetector. Figure 1(Not drawn in the middle) Above.

[0082] by Figure 3 For example, the specific working process of an all-fiber current transformer is as follows:

[0083] When the first signal processor is allocated time slot resources, its driving circuit drives the light source 10 to emit light. The light emitted by the light source 10 reaches the first end of the coupler 11, which then guides the light to the third end. After passing through the coupler 11, the light enters the polarizer 12, generating linearly polarized light. The linearly polarized light passes through the polarization beam splitter 13 and is split into two incident orthogonal linearly polarized beams with the same propagation direction. The two incident orthogonal linearly polarized beams pass through the phase modulator 14 and the transmission fiber 3, reaching one end of the λ / 4 waveplate 21 in the fiber optic sensing ring 2. The other end of the λ / 4 waveplate 21 in the fiber optic sensing ring 2 outputs two orthogonal circularly polarized beams. The two orthogonal circularly polarized beams propagate along the sensing fiber 22 of the fiber optic sensing ring 2. Due to the Faraday magneto-optical effect, in the sensing fiber 22, one of the two orthogonal circularly polarized beams propagates faster while the other propagates slower, thus generating a phase difference. After the two orthogonal circularly polarized beams are reflected by the mirror 23 at the end of the sensing fiber 22, the polarization modes of the two orthogonal circularly polarized beams are interchanged due to the effect of the mirror 23. The left-hand circularly polarized beam becomes the right-hand circularly polarized beam, and the right-hand circularly polarized beam becomes the left-hand circularly polarized beam, and then returns along the original path.

[0084] When the two returning orthogonal circularly polarized beams return, the direction of the magnetic field of the primary current remains unchanged, while the propagation direction and polarization state of the two returning orthogonal circularly polarized beams change, thus doubling the phase difference caused by the Faraday effect. After passing through the λ / 4 waveplate 21 of the fiber sensing ring 2 again, they become two returning orthogonal linearly polarized beams, and their polarization directions interchange during relative propagation. When the two returning orthogonal linearly polarized beams return, they pass sequentially through the transmission fiber 3, the phase modulator 14, and the polarization beam splitter 13 to become a combined polarized beam, which reaches the polarizer 12. The interference light signal returned by the polarizer 12 reaches the third end of the coupler 11, and then returns to the photodetector 15 through the second end of the coupler 11.

[0085] The photodetector 15 performs photoelectric conversion on the interference light signal and outputs an electrical signal. The first signal processor and the second signal processor 17 receive and demodulate the electrical signal to determine the measured current in the primary conductor 24 located in the optical fiber sensing loop 2.

[0086] The polarized X-rays and Y-rays output from polarization beam splitter 13 return to polarization beam splitter 13 with their polarization states interchanged. The optical path of the entire interference optical system is reciprocal. Since the two orthogonally polarized beams travel along the same path, the optical system exhibits good reciprocity and strong anti-interference capability. The influence of environmental factors such as vibration and stress on the all-fiber current transformer can be largely eliminated.

[0087] In this embodiment, the all-fiber optic current transformer's acquisition unit, transmission fiber, and fiber optic sensing ring work together to sense the primary current flowing through the conductors inside the fiber optic sensing ring. Based on the rated current of the current measurement point and the accuracy requirements for small current measurements, a first processor and a second processor are configured for different measurement ranges. The first and second processors on the signal processor board of the acquisition unit process the returned interference signals carrying primary current information and demodulate the current signal to be measured. The third processor switches between the two sets of data and outputs them to the control and protection system. This all-fiber optic current measurement device adapts to different measurement range requirements, simplifies the configuration of engineering measurement devices, and reduces the workload of subsequent operation and maintenance.

[0088] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0089] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A current measurement method, characterized in that, include: A first scale value and a second scale value are obtained, wherein the first scale value is obtained by the first processing module acquiring the current signal of the load, and the second scale value is obtained by the second processing module acquiring the current signal of the load, and the first scale value is smaller than the second scale value; Obtain the first rated value of the first processing module and the second rated value of the second processing module, wherein the first rated value is greater than the second rated value; Based on the first scale value and the first rated value, the first named value of the first processing module is obtained, and based on the second scale value and the second rated value, the second named value of the second processing module is obtained. Obtain a preset multiple between the first scale value and the second scale value. Based on the preset multiple, the first scale value, and the second scale value, determine a target processing module in the first processing module and the second processing module. Use the current collected by the target processing module as the measured current value of the load. Determining a target processing module among the first processing module and the second processing module based on the preset multiple, the first named value, and the second named value includes: multiplying the first named value and the preset multiple to obtain a product; comparing the product with the second named value, and determining the target processing module based on the comparison result; wherein, if the product is greater than or equal to the second named value, the first processing module is determined to be the target processing module; if the product is less than the second named value, the second processing module is determined to be the target processing module.

2. The current measurement method according to claim 1, characterized in that, Obtaining a preset multiple between the first scale value and the second scale value includes: Obtain a first preset scale value corresponding to the first rated value, and obtain a second preset scale value corresponding to the second rated value, wherein the first preset scale value is less than the second preset scale value; The preset multiple is obtained by the ratio of the first preset scale value and the second preset scale value.

3. The current measurement method according to claim 1, characterized in that, Based on the preset multiple, the first named value, and the second named value, a target processing module is determined in the first processing module and the second processing module, including: When it is determined that the first processing module is the target processing module, the time slot resources are allocated to the first processing module; When the second processing module is determined to be the target processing module, the time slot resources are allocated to the second processing module.

4. A current measuring device, characterized in that, include: The system comprises a control module, a first processing module, and a second processing module, wherein the control module is connected to both the first processing module and the second processing module; wherein... The first processing module is used to collect the current signal of the load and obtain a first scale value based on the current signal collected by the first processing module; The second processing module is used to acquire the current signal of the load and obtain a second scale value based on the current signal acquired by the second processing module; The control module is used to implement the current measurement method according to any one of claims 1-3.

5. The current measuring device according to claim 4, characterized in that, The first processing module includes: A first acquisition unit is connected to the load. The first acquisition unit acquires the current signal of the load according to a first acquisition frequency, wherein the first acquisition frequency is the intrinsic frequency of the load.

6. The current measuring device according to claim 5, characterized in that, The first processing module further includes: A first driving unit, connected to the load, is used to drive the light source of the load; A first signal generating unit, connected to the load, is used to drive the phase modulator of the load.

7. The current measuring device according to claim 4, characterized in that, The second processing module further includes: A second acquisition unit is connected to the load. The second acquisition unit acquires the current signal output by the load according to a second acquisition frequency, wherein the second acquisition frequency is greater than the intrinsic frequency of the load.

8. The current measuring device according to claim 7, characterized in that, The second processing module further includes: A second driving unit, connected to the load, is used to drive the light source of the load; A second signal generating unit, connected to the load, is used to drive the phase modulator of the load.

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