An optical current measurement device based on system gain adaptive control

Abstract

The present invention provides an optical current measuring device based on system gain adaptive control, which comprises a light source, a first optical fiber coupler, an optical waveguide, a second optical fiber coupler, a delay ring and a sensitive ring connected in sequence, and further comprises: a photodetector connected to the first optical fiber coupler; a system gain adaptive controller, a first end of which is connected to the photodetector and a second end is connected to the optical waveguide, and the system gain adaptive controller has a dual closed-loop control function and a system gain adaptive control function. The present invention realizes adaptive control of the system gain of the measuring device while ensuring the realization of the function of the dual closed-loop control system and without adding additional components, solves the problems that the forward channel gain of the existing optical current measuring device system is uncontrollable, resulting in poor product robustness and unreliable engineering application; and also solves the problems that other optical devices need to be added in order to realize the control of the system gain in the prior art, the process is difficult to realize, and the product reliability is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of optical current sensing, and in particular to an optical current measuring device based on system gain adaptive control. Background Art

[0002] Optical current measurement devices have the advantages of photoelectric isolation, digital output, wide measurement range, large bandwidth, both AC and DC can be measured, and there is no magnetic saturation. In recent years, they have been increasingly used in the fields of smart grids, high-voltage direct current transmission, and ship integrated power systems.

[0003] Conventional optical current measurement devices have exposed a series of serious shortcomings during engineering operation: the on-site splicing of polarization-maintaining optical fibers is cumbersome and there are deviations in the splicing loss; the optical current measurement device needs to be recalibrated after the sensitive ring is re-splice at the construction site; the light source of the optical current measurement device attenuates after long-term operation, resulting in a decrease in the performance of the current measurement index or even unavailability.

[0004] Driven by the demand for power system and smart grid construction, optical current measurement devices based on Faraday magneto-optical effect and Ampere loop theorem have made great technological breakthroughs in recent years and are widely used in newly built intelligent substations. However, the primary sensitive ring and electrical unit of the current measurement device based on this principle are connected by polarization-maintaining fiber. The quality of polarization-maintaining fiber fusion and the fluctuation of light source optical power directly change the gain of the feedforward channel of the measurement device, which will cause the measurement performance index to decline or even become unusable for systems without gain control.

[0005] In engineering applications, in order to ensure the stability of the system optical power, the fiber optic current measurement device usually uses a constant current source and a temperature control circuit to achieve a stable output of the light source optical power. However, this solution can only ensure that the driving current of the light source remains unchanged. As the light source increases in working time, it will inevitably decay, which will lead to a decrease in the output optical power and a decrease in the forward channel gain of the system. In order to solve this problem, some measurement device systems feed back the light source optical power to the system through a detector during system design, thereby achieving a stable output of the light source output optical power. Although this solution can achieve a stable output of optical power, it still cannot guarantee the stability of the final interference light intensity of the system, and the optical path becomes more complicated, reducing reliability.

[0006] Therefore, the present invention provides an optical current measurement device based on system gain adaptive control. Summary of the invention

[0007] The technical problem to be solved by the present invention is: how to solve the problem of degradation of performance indicators such as synchronization consistency (angular difference) of the measuring device caused by changes in system control gain due to attenuation of system light source optical power and fiber fusion during on-site construction of the optical current measuring device without changing the hardware solution of the existing measuring device, so as to improve the reliability of the product.

[0008] To solve the above problems, the present invention provides an optical current measurement device based on system gain adaptive control, the device comprising a light source, a first optical fiber coupler, an optical waveguide, a second optical fiber coupler, a delay ring and a sensitive ring connected in sequence, the device also comprising:

[0009] a photodetector connected to the first optical fiber coupler;

[0010] A system gain adaptive controller has a first end connected to the photodetector and a second end connected to the optical waveguide. The system gain adaptive controller has a dual closed-loop control function and a system gain adaptive control function.

[0011] According to an embodiment of the present invention, the light source is fused to the first input end of the first optical fiber coupler.

[0012] According to an embodiment of the present invention, the photodetector is fused to the second input end of the first optical fiber coupler.

[0013] According to an embodiment of the present invention, the input end of the optical waveguide is fused to the first output end of the first optical fiber coupler.

[0014] According to one embodiment of the present invention, the first output end of the optical waveguide is fused to the first input end of the second optical fiber coupler, and the second output end of the optical waveguide is fused to the second input end of the second optical fiber coupler.

[0015] According to an embodiment of the present invention, the delay ring and the sensitive ring are sequentially connected to the first output end of the second optical fiber coupler.

[0016] According to an embodiment of the present invention, the system gain adaptive controller includes a feedback gain module, which includes: a digital-to-analog conversion unit, a power amplifier unit, and a feedback phase modulation unit.

[0017] According to one embodiment of the present invention, the system gain adaptive controller includes a forward channel gain module, and the forward channel gain module includes a gain coefficient unit, which is used to measure the forward channel gain to achieve adaptive control of the forward channel gain of the optical current measurement device by adjusting the gain coefficient.

[0018] According to an embodiment of the present invention, the forward channel gain module includes: a photoelectric conversion unit, a transimpedance unit, a preamplifier unit, an analog-to-digital conversion unit, and a digital demodulation unit.

[0019] According to an embodiment of the present invention, the system gain adaptive controller includes a feedback coefficient module, which cooperates with the feedback gain module to implement feedback channel gain adjustment of the optical current measurement device.

[0020] The optical current measuring device based on system gain adaptive control provided by the present invention realizes adaptive control of the system gain of the optical current measuring device while ensuring the functions of the dual closed-loop control system and without adding additional components, thereby solving the problems that the forward channel gain of the existing optical current measuring device system is uncontrollable, resulting in poor product robustness and unreliable engineering applications; it also solves the problems in the prior art that in order to realize the control of the system gain, other optical devices need to be added, the process is difficult to implement, and the product reliability is reduced.

[0021] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 A structural block diagram of an optical current measurement device based on system gain adaptive control according to an embodiment of the present invention is shown;

[0024] Figure 2 A structural block diagram of an optical current measurement device based on system gain adaptive control according to another embodiment of the present invention is shown;

[0025] Figure 3 A block diagram of a system gain adaptive controller according to an embodiment of the present invention is shown; and

[0026] Figure 4 A structural block diagram of a system gain adaptive controller according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0028] Figure 1The structure block diagram of an optical current measurement device based on system gain adaptive control according to an embodiment of the present invention is shown.

[0029] like Figure 1 As shown, the optical current measuring device includes a light source 101 , a first fiber coupler 102 , an optical waveguide 103 , a second fiber coupler 104 , a delay ring 105 , a sensitive ring 106 , a photodetector 107 and a system gain adaptive controller 108 .

[0030] Specifically, if Figure 1 As shown, the light source 101 , the first fiber coupler 102 , the optical waveguide 103 , the second fiber coupler 104 , the delay ring 105 and the sensitive ring 106 are connected in sequence. The photodetector 107 is connected to the first fiber coupler 102 .

[0031] like Figure 1 As shown, a first end of the system gain adaptive controller 108 is connected to the photodetector 107 , and a second end is connected to the optical waveguide 103 . The system gain adaptive controller 108 has a dual closed-loop control function and a system gain adaptive control function.

[0032] Specifically, the light source 101 is fused with the first input end of the first optical fiber coupler 102. In one embodiment, the light source 101 is fused with the first input end of the first optical fiber coupler 102 at 0 degrees.

[0033] Specifically, the photodetector 107 is fused to the second input end of the first optical fiber coupler 102. In one embodiment, the photodetector 107 is fused to the second input end of the first optical fiber coupler 102 at 0 degrees.

[0034] Specifically, the input end of the optical waveguide 103 is fused with the first output end of the first optical fiber coupler 102 , the first output end of the optical waveguide 103 is fused with the first input end of the second optical fiber coupler 104 , and the second output end of the optical waveguide 103 is fused with the second input end of the second optical fiber coupler 104 .

[0035] In one embodiment, the input end of the optical waveguide 103 is fused with the first output end of the first optical fiber coupler 102 at 0 degrees, the first output end of the optical waveguide 103 is fused with the first input end of the second optical fiber coupler 104 at 90 degrees, and the second output end of the optical waveguide 103 is fused with the second input end of the second optical fiber coupler 104 at 0 degrees.

[0036] Specifically, the delay ring 105 and the sensitive ring 106 are sequentially connected to the first output end of the second optical fiber coupler 104. In one embodiment, the delay ring 105 and the sensitive ring 106 are fused to the first output end of the second optical fiber coupler 104 at 0 degrees.

[0037] In one embodiment, the system gain adaptive controller 108 includes a feedback gain module, which includes: a digital-to-analog conversion unit, a power amplifier unit, and a feedback phase modulation unit.

[0038] In one embodiment, the system gain adaptive controller 108 comprises a forward channel gain module, which comprises a gain coefficient unit for measuring the forward channel gain to achieve adaptive control of the forward channel gain of the optical current measurement device by adjusting the gain coefficient.

[0039] Furthermore, the forward channel gain module includes: a photoelectric conversion unit, a transimpedance unit, a preamplifier unit, an analog-to-digital conversion unit and a digital demodulation unit.

[0040] In one embodiment, the system gain adaptive controller 108 includes a feedback coefficient module, which cooperates with the feedback gain module to implement feedback channel gain adjustment of the optical current measurement device.

[0041] The optical current measuring device based on system gain adaptive control provided by the present invention realizes adaptive control of the system gain of the optical current measuring device while ensuring the functions of the dual closed-loop control system and without adding additional components, thereby solving the problems that the forward channel gain of the existing optical current measuring device system is uncontrollable, resulting in poor product robustness and unreliable engineering applications; it also solves the problems in the prior art that in order to realize the control of the system gain, other optical devices need to be added, the process is difficult to implement, and the product reliability is reduced.

[0042] Figure 2 A structural block diagram of an optical current measurement device based on system gain adaptive control according to another embodiment of the present invention is shown.

[0043] Specifically, the light source 101 adopts a superluminescent diode (SLD), the first fiber coupler 102 and the second fiber coupler 104 adopt 2*2 double-input double-output polarization-maintaining couplers, and the optical waveguide 103 adopts a Y-type branch waveguide.

[0044] In one embodiment, the light source 101 is fused with the first input end (A1 end) of the first optical fiber coupler 102 at 0 degrees, the photodetector 107 is fused with the second input end (A2 end) of the first optical fiber coupler 102 at 0 degrees, the input end of the optical waveguide 103 is fused with the first output end (A3 end) of the first optical fiber coupler 102 at 0 degrees, and the second output end (A4 end) of the first optical fiber coupler 102 is a blank end.

[0045] In addition, the first output end (Y1 end) of the optical waveguide 103 is fused with the first input end (B1 end) of the second optical fiber coupler 104 at 90 degrees, the second output end (Y2 end) of the optical waveguide 103 is fused with the second input end (B2 end) of the second optical fiber coupler 104 at 0 degrees, the first output end (B3 end) of the second optical fiber coupler 104 is fused with the optical fiber ring (including the delay ring 105 and the sensitive ring 106) at 0 degrees, and the second output end (B4 end) of the second optical fiber coupler 104 is a blank end.

[0046] Figure 3 A structural block diagram of a system gain adaptive controller according to an embodiment of the present invention is shown.

[0047] like Figure 3 As shown, the system gain adaptive controller 108 includes a forward channel gain module 301 , a feedback gain module 302 , and a feedback coefficient module 303 .

[0048] Specifically, the forward channel gain module 301 can measure the forward channel gain to achieve adaptive control of the forward channel gain of the optical current measurement device by adjusting the gain coefficient. The feedback gain module 302 can achieve feedback gain control of the optical current measurement device through double closed-loop control. The feedback coefficient module 303 cooperates with the feedback gain module 302 to achieve feedback channel gain adjustment of the optical current measurement device.

[0049] Figure 4 A structural block diagram of a system gain adaptive controller according to another embodiment of the present invention is shown.

[0050] like Figure 4 As shown, the current I is input into the system gain adaptive controller 108, and firstly passes through the current sensitive detector 401 (K0) to convert the current signal into a voltage signal.

[0051] Specifically, if Figure 4 As shown, the forward channel gain module 301 (G′) includes an optical-to-electrical conversion unit 402 ( K1 ), a transimpedance unit 403 ( K2 ), a preamplifier unit 404 ( K3 ), an analog-to-digital conversion unit 405 ( K4 ), a digital demodulation unit 406 ( K5 ) and an integration unit 407 .

[0052] Specifically, if Figure 4 As shown, the forward channel gain module 301 further includes a gain coefficient unit 408, which is used to measure the forward channel gain, so as to achieve adaptive control of the forward channel gain of the optical current measurement device by adjusting the gain coefficient Kz.

[0053] Specifically, if Figure 4As shown, the feedback gain module 302 (M′) includes: a digital-to-analog conversion unit 409 ( K6 ), a power amplifier unit 410 ( K7 ) and a feedback phase modulation unit 411 ( K8 ).

[0054] Specifically, if Figure 4 As shown, the system gain adaptive controller 108 further includes a feedback coefficient module 303, which cooperates with the feedback gain module 302 to implement feedback channel gain adjustment of the optical current measurement device. Further, the feedback coefficient module 303 implements feedback channel gain adjustment of the optical current measurement device through the feedback coefficient Kf.

[0055] In the prior art, the equivalent transfer function of the optical circuit measurement device system based on conventional double closed-loop control can be equivalent to the following formula (1):

[0056]

[0057] Among them, G is the system forward channel gain, M is the system feedback channel gain, τ c ′ is the time constant of the system. In addition,

[0058] The present invention is different from the conventional dual closed-loop controlled optical circuit measuring device in the prior art. After being used for a period of time, the optical circuit measuring device in the prior art will have the problem of degradation of performance indicators such as the synchronization consistency (angular difference) of the measuring device due to the attenuation of the light source light power and the change of the system control gain caused by the fiber fusion during on-site construction.

[0059] The forward channel gain module 301 of the present invention includes a gain coefficient unit 408, which can perform adaptive adjustment of the system gain after the light source optical power is attenuated and the system control gain changes, and can well solve the problems of the prior art.

[0060] In the present invention, the forward channel gain is G'=GK, and the transfer function of the system remains unchanged compared to the prior art. By controlling the forward channel gain, G' can be kept constant. Combined with feedback gain control, the overall system gain G'M' can also remain unchanged, thereby strictly controlling the system's damping ratio, resonant frequency, response time and stability.

[0061] Compared with the dual closed-loop controller in the prior art, the system gain adaptive controller 108 of the present invention adds adaptive control of the gain of the control system of the optical current measurement device, adopts feedforward, feedback, cascade control combined with complex control methods, based on the MIT adaptive control method and local parameter optimal design theory, and applies fast feedforward control on the basis of the technology of accurate real-time detection of the forward channel gain.

[0062] In summary, the gain adaptive control of the optical current measuring device is achieved through the feedforward control gain coefficient unit 408, which solves the problem of serious deviations of indicators such as the angular error or synchronization consistency of the measuring device caused by a decrease in the system forward channel gain due to light source attenuation, increased on-site optical fiber laying and fusion loss, etc., thereby improving the robustness and environmental adaptability of the measuring device system.

[0063] In addition, through the system gain adaptive controller 108 provided by the present invention, the feedback gain and the forward channel gain can be controlled separately, thereby optimizing the optical current measurement device. Specifically:

[0064] (1) The system gain adaptive controller 108 adjusts the overall system gain G'M' so that the time constant It meets the requirement of short unit step response time, and thus meets the response time requirement of new fast circuit breakers.

[0065] (2) Through the second closed-loop feedback of the system gain adaptive controller 108, the feedback channel gain can be stably controlled to achieve stable control of the scale factor of the optical fiber current measurement device.

[0066] (3) The system gain adaptive controller 108 controls the overall system gain through feedback and feedforward complex control technology to achieve a constant overall system gain G'M', thereby further achieving the requirement of stable response time.

[0067] (4) The system gain adaptive controller 108 designs the best system damping and controls the damping of the system by keeping the overall system gain G'M' constant, thereby preventing system overshoot and oscillation, and thus achieving the control system stability requirement.

[0068] In summary, the present invention has the following beneficial effects compared with the prior art:

[0069] (1) The system gain adaptive controller 108 of the present invention can realize the measurement of the effective interference optical power of the optical current measurement device without adding additional photodetectors and other devices. It adopts feedforward, feedback, cascade control combined with complex control methods, based on the MIT adaptive control method and local parameter optimal design theory, and applies fast feedforward control on the basis of accurate real-time detection of forward channel gain. It realizes real-time monitoring of system gain and automatic adjustment of feedback gain coefficient, which improves the robustness and adaptability of the system;

[0070] (2) The system gain adaptive controller 108 used in the present invention solves the gain fluctuation of the optical path and circuit of the optical current measurement device to the forward channel compared with the conventional double closed-loop controller in the prior art, thereby improving the performance indicators such as the accuracy of the optical current measurement device in high and low temperature environments;

[0071] (3) Generally speaking, the optical current measurement device causes a large change in the system optical path loss during the on-site laying of optical fibers, and the system gain decreases, which increases the response time of the measurement system, and further causes the angular difference and synchronization consistency indicators to exceed the standard. The system gain adaptive controller 108 used in the present invention can monitor the measurement system gain, and solve the above problems well through feedforward feedback control, thereby greatly improving the environmental adaptability and reliability of the optical current measurement device.

[0072] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0073] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0074] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. An optical current measurement device based on system gain adaptive control, characterized in that: The optical current measuring device comprises a light source, a first optical fiber coupler, an optical waveguide, a second optical fiber coupler, a delay ring and a sensitive ring connected in sequence, and the optical current measuring device further comprises: a photodetector connected to the first optical fiber coupler; A system gain adaptive controller, a first end of which is connected to the photodetector, and a second end of which is connected to the optical waveguide, wherein the system gain adaptive controller has a dual closed-loop control function and a system gain adaptive control function; The current is input into the system gain adaptive controller, and firstly the current signal is converted into a voltage signal by a current sensitive detector; The system gain adaptive controller comprises a forward channel gain module, a feedback gain module and a feedback coefficient module; The forward channel gain module measures the forward channel gain to achieve adaptive control of the forward channel gain of the optical current measurement device by adjusting the gain coefficient; the feedback gain module achieves feedback gain control of the optical current measurement device through double closed-loop control; the feedback coefficient module cooperates with the feedback gain module to achieve feedback channel gain adjustment of the optical current measurement device; wherein, the feedback coefficient module achieves feedback channel gain adjustment of the optical current measurement device through the feedback coefficient; The forward channel gain module comprises a photoelectric conversion unit, a transimpedance unit, a preamplifier unit, an analog-to-digital conversion unit, a digital demodulation unit and an integration unit; the forward channel gain module further comprises a gain coefficient unit, which is used to measure the forward channel gain, so as to achieve adaptive control of the forward channel gain of the optical current measurement device by adjusting the gain coefficient; The feedback gain module includes: a digital-to-analog conversion unit, a power amplifier unit and a feedback phase modulation unit.

2. An optical current measurement device based on system gain adaptive control as claimed in claim 1, characterized in that: The light source is fused to the first input end of the first optical fiber coupler.

3. The optical current measurement device based on system gain adaptive control according to claim 1, characterized in that: The photoelectric detector is fused to the second input end of the first optical fiber coupler.

4. The optical current measurement device based on system gain adaptive control according to claim 1, characterized in that: The input end of the optical waveguide is fused to the first output end of the first optical fiber coupler.

5. The optical current measurement device based on system gain adaptive control according to claim 1, characterized in that: The first output end of the optical waveguide is fused to the first input end of the second optical fiber coupler, and the second output end of the optical waveguide is fused to the second input end of the second optical fiber coupler.

6. The optical current measurement device based on system gain adaptive control according to claim 1, characterized in that: The delay ring and the sensitive ring are sequentially connected to the first output end of the second optical fiber coupler.

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