Converter station FOCT error calculation method considering fusion point error

Abstract

The invention provides a converter station FOCT error calculation method considering fusion point errors, and belongs to the technical field of electric power measurement. Comprising the following steps: constructing a simulation model corresponding to an optical component according to a Jones matrix of each optical component in FOCT by using Simulink simulation software; constructing an FOCT error calculation model according to the simulation model of the optical component and the connection relation of the simulation model; and adjusting fusion point parameters in the error calculation model, and analyzing the influence of different parameters on the FOCT measurement performance. According to the method, firstly, each optical component of an FOCT light path system is replaced with a simulation model, then the simulation models of the components are combined to form an FOCT error calculation model according to the connection relation of the optical components of the FOCT and actual input and output, the error calculation model can directly reflect the working process of the FOCT, and the error calculation model can directly reflect the working process of the FOCT. Parameters of each optical component are concerned in simulation, so that influence factors can be analyzed conveniently; by adjusting the corresponding parameters of the 45-degree fusion welding point part, the influence of different conditions of the fusion welding points on the final measurement performance of the FOCT can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of electric power measurement, and in particular relates to a converter station FOCT error calculation method taking into account a welding point error. Background Art

[0002] FOCT (Fiber Optic Current Transformer) has the advantages of light weight, good insulation performance, strong anti-interference ability, high reliability and high degree of digitization. Compared with traditional electromagnetic current transformers, it has better safety, wider measurement range and stronger stability, and meets the needs of the development of informationization, digitization and automation of the new generation of smart grids.

[0003] The most basic working principle of FOCT is the Faraday magneto-optical rotation effect: the current-carrying conductor to be measured generates a magnetic field due to the principle of electromagnetic induction, and the sensing optical fiber is ring-shaped around the current-carrying conductor. The polarized light propagating in the optical fiber undergoes the Faraday magneto-optical rotation effect due to the magnetic field. By measuring the size of the Faraday rotation angle, the light wave deflection signal is converted into an electrical signal, thereby obtaining the measured current value. This Faraday magneto-optical rotation effect requires that the light wave can maintain a good polarization state during the propagation of the FOCT optical path. In FOCT, sensing optical fibers with good circular polarization retention capabilities are generally used to meet this requirement.

[0004] Due to the problem of welding process, there is a welding angle error at the 45° welding point in FOCT, and the light no longer propagates completely along the transmission axis, affecting the overall optical transmission performance; the welding angle error will also cause the sensing optical fiber connection to be poor, which may cause the light transmission path to deviate from the expected trajectory, increase the light loss at the optical fiber connection, affect the quality of the optical signal, reduce the FOCT measurement performance, and affect the accuracy of current measurement.

[0005] At present, many researchers have achieved many research results in the optimization of FOCT structure and parameters, but there is no relevant research on the influence of welding point error on FOCT measurement performance in the existing technology. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for calculating the FOCT error of a converter station taking into account the error of a welding point.

[0007] In order to solve one, part or all of the above technical problems, the technical solution adopted by the present invention is: A method for calculating FOCT error of a converter station considering a welding point error includes: Using Simulink simulation software, the simulation model corresponding to the optical component is constructed according to the Jones matrix of each optical component in FOCT; The FOCT error calculation model is constructed based on the simulation model of the optical components and their connection relationships; The welding point parameters were adjusted in the error calculation model, and the influence of different parameters on the FOCT measurement performance was analyzed.

[0008] Furthermore, the method for adjusting the parameters of the fusion point in the error calculation model includes: adjusting the parameter settings of the 45° fusion point part in the error calculation model; the parameters include insertion loss, reflection loss, polarization mode dispersion and mode coupling.

[0009] Furthermore, the optical components include a light source, a polarizer, an analyzer, a 45° fusion point, a 1 / 4 wave plate, a sensing optical fiber and a photodetector.

[0010] Furthermore, the incident Jones matrix of the polarizer is expressed as , the Jones matrix is ​​returned as .

[0011] Furthermore, the incident Jones matrix of the 45° welding point is expressed as , the Jones matrix is ​​returned as .

[0012] Furthermore, the incident Jones matrix of the phase modulator is expressed as , the Jones matrix is ​​returned as .

[0013] Furthermore, the incident Jones matrix of the 1 / 4 wave plate is expressed as , the Jones matrix is ​​returned as .

[0014] Furthermore, the incident Jones matrix of the sensing fiber is expressed as , the Jones matrix is ​​returned as .

[0015] Furthermore, the incident Jones matrix of the analyzer is expressed as .

[0016] The design of the FOCT welding point, the manufacturing quality, and the slight deviations that may occur during the installation process will introduce errors and affect the accuracy of current measurement. Therefore, it is very important to consider the impact of the welding point on the error measurement characteristics of FOCT. However, existing research lacks simulation modeling analysis of the welding point according to the FOCT structure, and cannot intuitively reflect the impact of changes in welding point related parameters on the FOCT measurement performance. Moreover, most of the current FOCT simulation models are based on the overall mathematical model of FOCT, rather than on the various components of FOCT. Although the functions implemented by this model correspond to the principles of FOCT, for FOCT, only by modeling each component can the functional principles of each module component in FOCT be more intuitively reflected.

[0017] In view of the above problems, the present invention first replaces each optical component of the FOCT optical path system with a simulation model, and then combines the simulation models of these components according to the connection relationship of the FOCT optical components and the actual input and output to form a FOCT error calculation model. The error calculation model can directly reflect the working process of FOCT, pay attention to the parameters of each optical component in the simulation, and facilitate the analysis of influencing factors and improve the visualization effect. By adjusting the corresponding parameters of the 45° welding point part, the influence of different welding point conditions on the final measurement performance of FOCT can be obtained. The present invention is of great significance for reducing the influence of welding errors, improving the measurement performance of FOCT, and promoting the development of FOCT. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0019] Figure 1 : Schematic diagram of the structure of FOCT; Figure 2 : Schematic diagram of the structure of the FOCT error calculation model of the present invention. DETAILED DESCRIPTION

[0020] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the embodiments and the accompanying drawings, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0021] Example 1: See Figure 1-Figure 2 ,The purpose of this embodiment is to provide a method for calculating the FOCT error of a converter station taking the welding point error into consideration.

[0022] like Figure 1The figure shows the schematic diagram of the structure of FOCT. FOCT is mainly composed of a light source, a polarizer, an analyzer, a 45° fusion point, a 1 / 4 wave plate, a sensing optical fiber and a photodetector, which together complete the functions of light emission, polarization, phase modulation, optical delay, photoelectric detection and amplification, and measured current solution. Among them, the light emitted by the light source passes through the coupler and polarizer to form linear polarized light, and then is divided into two beams of orthogonal polarized light at the 45° fusion point; after the phase modulator applies optical path difference modulation and transmits through the polarization-maintaining delay fiber ring, the two beams of polarized light pass through the 1 / 4 wave plate and enter the optical sensor head, and are converted into left-handed and right-handed circularly polarized light, and produce phase shift under the Faraday magneto-optical effect of the measured primary current; when the two beams of light reach the tail end of the optical fiber, they are reflected by the reflector and return along the original path, and the polarization states of the two are exchanged, and the Faraday magneto-optical effect is generated again after experiencing the magnetic field, and the phase difference generated by the two circularly polarized lights is doubled, and after passing through the 1 / 4 wave plate, it becomes linear polarized light again, realizing the exchange of polarization directions; finally, the light intensity carrying the current information is output through the coupler, and reaches the photodetector after passing through the analyzer, and the signal processing unit detects the interference phase difference of the two polarized lights to realize the current measurement.

[0023] The error calculation method comprises: S1. Use Jones operation to build a simulation model of optical components in FOCT.

[0024] In FOCT, only the light source uses real scalars, and the Jones matrices of other optical polarization devices are all in complex form. The input and output quantities of the optical polarization devices in the light path are all vectors, so this step uses Simulink simulation software to perform simulation modeling separately according to the Jones matrices of each optical component of FOCT.

[0025] Specifically, this step performs simulation modeling according to the Jones matrix of the POCT light source, polarizer, analyzer, 45° fusion point, 1 / 4 wave plate, sensing optical fiber and photodetector.

[0026] (1) Light source modeling The light source is one of the core components of the all-fiber current transformer. Its main function is to generate a stable optical signal and transmit it to the entire system through optical fiber. The light emitted by the light source can be further processed by the polarizer to interact with the change of current. The stability of the light source is crucial to the measurement accuracy of the system, especially in the process of optical fiber transmission, the stability of the light source directly affects the final signal strength and quality.

[0027] Assuming that the light beam emitted by the light source propagates along the Z axis, the incident Jones matrix of the POCT input light is expressed as , the Jones matrix is ​​returned as .

[0028] (2) Polarizer modeling Polarizers are used to convert light emitted by a light source into (linearly polarized light) to control the polarization state of light. The properties of polarized light are crucial for subsequent signal processing, ensuring that light waves produce a clear response to changes in the magnetic field associated with the current.

[0029] The incident Jones matrix of the polarizer is expressed as , the Jones matrix is ​​returned as .

[0030] (3) Modeling of 45° welding point The 45° splice is a key component in the optical fiber transmission path. Its main function is to adjust the direction of light propagation in the optical fiber. In the FOCT system, the core part of the optical fiber needs to be spliced ​​at a specific angle to achieve the steering of the light beam propagation. The 45° angle design enables the light waves to be refracted or reflected to ensure that the signal can be transmitted along the predetermined path. 45° is the angle between the two fast axes of two polarization-maintaining optical fibers. The function of the 45° splice is to split the light in the original fast axis and slow axis into two beams for transmission in the new fast axis and slow axis respectively.

[0031] The incident Jones matrix of the 45° welding point is expressed as , the Jones matrix is ​​returned as .

[0032] (4) Phase modulator modeling The phase modulator changes the phase of the light wave transmitted in the optical fiber under external drive.

[0033] The incident Jones matrix of the phase modulator is expressed as , the Jones matrix is ​​returned as .

[0034] (5) 1 / 4 wave plate module modeling The 1 / 4 wave plate is used to change the phase of the light wave. By introducing phase delay, the polarization state of the light changes, which in turn affects the relationship between the optical signal and the current measurement. For example, through appropriate phase adjustment, the optical signal caused by the magnetic field change can be amplified or reduced, thereby improving the measurement sensitivity of the fiber-optic current transformer. If the polarization direction of the light is aligned with the fast and slow axes of the wave plate, different types of circularly polarized light (left-handed or right-handed circularly polarized light) can also be obtained.

[0035] The incident Jones matrix of the quarter wave plate is expressed as , the Jones matrix is ​​returned as .

[0036] (6) Sensing fiber modeling The sensing fiber is the part of the fiber optic current transformer that senses current changes and is usually laid around the current conductor. The sensing fiber is mainly used to sense the changes in the magnetic field caused by the current and convert these changes into optical signals. Specifically, the sensing fiber uses the polarization state or phase change of the light propagating in the optical fiber to reflect the changes in the external magnetic field, thereby reflecting the magnitude of the current.

[0037] The incident Jones matrix of the sensing fiber is expressed as , the Jones matrix is ​​returned as .

[0038] (7) Mirror modeling The reflector is arranged at the tail end of the sensing optical fiber and is used to reflect the light and return it to its original path.

[0039] The incident Jones matrix of the reflector is expressed as , the Jones matrix is ​​returned as .

[0040] (8) Analyzer modeling The analyzer is a component opposite to the polarizer, used to analyze and adjust the polarization state of the light signal. By rotating the analyzer, its angle relative to the polarizer can be changed, thereby affecting the polarization state of the light. By adjusting the polarization state, the analyzer can effectively detect changes in light intensity associated with changes in current.

[0041] The incident Jones matrix of the analyzer is expressed as .

[0042] (9) Photodetector modeling Photoelectric detector is one of the key components in all-fiber current transformer. Its function is to convert the optical signal transmitted by the sensing optical fiber into an electrical signal. The photoelectric detector converts the change of light intensity transmitted through the optical fiber into current or voltage signals. These signals are proportional to the magnitude of the current change, thereby realizing the measurement and monitoring of the current.

[0043] The light wave transmission quantity in the photodetector is converted from vector form to scalar form.

[0044] S2. Construct a FOCT error calculation model based on the simulation model of the optical components and their connection relationships.

[0045] According to the optical components that light passes through in FOCT, the simulation models of the optical components in FOCT are connected in Simulink simulation software to build the FOCT error calculation model. The structure of the FOCT error calculation model is as follows: Figure 2 shown.

[0046] S3. Adjust the welding point parameters in the error calculation model and analyze the influence of different parameters on the FOCT measurement performance.

[0047] In the error calculation model, the corresponding parameter settings of the 45° splice are adjusted, such as insertion loss, return loss, polarization mode dispersion (PMD) and mode coupling. By setting the input and analyzing the measurement results, the impact of different splice conditions on the final measurement performance of FOCT can be obtained.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for calculating the FOCT error of a converter station considering the welding point error, characterized in that: include: Using Simulink simulation software, the simulation model corresponding to the optical component is constructed according to the Jones matrix of each optical component in FOCT; The FOCT error calculation model is constructed based on the simulation model of the optical components and their connection relationships; The welding point parameters were adjusted in the error calculation model, and the influence of different parameters on the FOCT measurement performance was analyzed.

2. The converter station FOCT error calculation method considering the welding point error according to claim 1 is characterized in that: The method for adjusting the parameters of the fusion point in the error calculation model includes: adjusting the parameter settings of the 45° fusion point part in the error calculation model; the parameters include insertion loss, reflection loss, polarization mode dispersion and mode coupling.

3. The converter station FOCT error calculation method considering the welding point error according to claim 1 is characterized in that: The optical components include a light source, a polarizer, an analyzer, a 45° fusion point, a 1 / 4 wave plate, a sensing optical fiber and a photoelectric detector.

4. The method for calculating the FOCT error of a converter station considering the welding point error according to claim 3 is characterized in that: The incident Jones matrix of the polarizer is expressed as , the Jones matrix is ​​returned as .

5. The method for calculating the FOCT error of a converter station considering the welding point error according to claim 3 is characterized in that: The incident Jones matrix of the 45° welding point is expressed as , the Jones matrix is ​​returned as .

6. The method for calculating the FOCT error of a converter station considering the welding point error according to claim 3 is characterized in that: The incident Jones matrix of the phase modulator is expressed as , the Jones matrix is ​​returned as .

7. The method for calculating the FOCT error of a converter station considering the welding point error according to claim 3, characterized in that: The incident Jones matrix of the 1 / 4 wave plate is expressed as , the Jones matrix is ​​returned as .

8. The method for calculating the FOCT error of a converter station considering the welding point error according to claim 3 is characterized in that: The incident Jones matrix of the sensing fiber is expressed as , the Jones matrix is ​​returned as .

9. The method for calculating the FOCT error of a converter station considering the welding point error according to claim 3, characterized in that: The incident Jones matrix of the analyzer is expressed as .

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