RU85671U1 - INFORMATION-MEASURING SYSTEM FOR MEASURING AND CONTROL OF ELECTRIC CURRENT - Google Patents

Abstract

Information-measuring system for measuring and monitoring electric current, containing a series-connected optical radiation source in the form of a laser or a laser diode, a polarizer, a phase plate, polarization-preserving optical fiber with linear birefringence, rolled into a coil, inside of which there is a current conductor, a divider optical fibers, polarization dividers, optical radiation photodetector, characterized in that as optical radiation photodetectors with Exit divisors used polarized photodiodes electrically connected with amplifiers and analog-to-digital converters, the outputs of which are connected to the microcontroller comprising information processing unit and the communication node.

Description

The utility model relates to the field of electrical measurements and can be used in the electric power industry, in measuring equipment, in the field of relay protection and automation of substations.

Known information-measuring device for monitoring the electric current and magnetic field (German patent No. 19547021, IPC G01R 15/24, publ. 06/19/97), including an optically coupled sensor based on the magneto-optical Faraday effect, which changes the polarization of the light signal depending on a variable, means for inputting a polarized light signal into the sensor, means for dividing the polarized light signal into a pair of mutually orthogonal linearly polarized components, as well as a conversion unit for these components.

The disadvantage of this device is the low accuracy and stability of measurements in real operating conditions, associated with an uncontrolled change in the state of polarization of the light signal during the measurement process, in particular, as a result of external factors (temperature, vibration, etc.).

For the prototype adopted information-measuring system for measuring and controlling electric current (RF patent No. 23211000, IPC G01R 15/24, 2006), containing an optical radiation source in the form of a laser or laser diode, a polarizer, a phase plate that preserves the polarization of an optical fiber with a linear birefringence, rolled into a coil, optical fiber divider, polarization dividers, optical radiation photodetector, low-pass filters and processing unit.

The disadvantage of this sensor is the insufficiently high accuracy of measurements and limited functionality due to the lack of devices for processing and storing information about the measured values of electric currents.

The task to which the utility model is directed is to increase the accuracy of measurements and expand the functionality.

The problem is solved in that in the information-measuring system for measuring and monitoring electric current, containing a series-connected source of optical radiation in the form of a laser or a laser diode, a polarizer, a phase plate, polarization-preserving optical fiber having linear birefringence, rolled into a coil, inside which is a conductor with current, an optical fiber divider, polarization dividers, an optical radiation photodetector, in contrast to the prototype as optical radiation photodetectors from the outputs of polarizing dividers used photodiodes electrically connected to amplifiers and analog-to-digital converters, the outputs of which are connected to a microcontroller containing an information processing unit, and a communication center.

In FIG. the structural diagram of the inventive information-measuring system for measuring and controlling electric current is given.

The electric current measurement and control system contains 1 laser or a laser diode as a source of optical radiation. A polarizer 2 is connected in series with the optical radiation source 1, a phase plate 3, a polarization-preserving optical fiber having linear birefringence, rolled into a coil 4. A conductor 5 with a measured current I passes inside the coil 4, and a linear birefringence-maintaining polarization-preserving optical fiber is connected. rolled up into a coil 4, an optical fiber splitter 6 is optically connected, polarization dividers 7 and 8, an optical radiation detector consisting of photodiodes 9-12 and amplifiers 13-16. Each optical radiation photodetector is electrically connected to each analog-to-digital converters 17-20. Analog-to-digital converters 17-20 are electrically connected to the microcontroller 21, containing the information processing unit. For reprogramming the microcontroller 21, as well as for communication with external devices via a digital output, a communication unit 22 is connected to the microcontroller.

The inventive information-measuring system operates as follows.

When the light emitted by the laser or laser diode 1 passes through the polarizer 2, it becomes plane-polarized. When an electric current I passes through conductor 5, a magnetic field is created around it, the intensity of which, according to the law of the total current, is defined as

where R is the distance from the current conductor to the point in question.

In the case of measuring the magnetic field, the latter directly affects the sensitive element in the form of a coil 3 of optical fiber.

An optical fiber coil serves as the magneto-optical element of Faraday. When exposed to a magnetic field, the plane of polarization of the plane-polarized light beam is rotated by the angle of the Faraday rotation

where I is the electric current;

N _o - the number of turns of the coil of optical fiber;

V is the Verde constant.

With direct exposure to a magnetic field, the angle of Faraday rotation is found by the formula

where L is the path length of light in a coil of optical fiber.

In the polarization divider 6, the light signal is divided into a pair of mutually orthogonal linearly polarized components (P) and (S) of optical power,

where m is the modulation depth, P ₀ is the light power in the absence of a magnetic field.

The value of the measured signal will be equal to the ratio

The use of two polarization dividers 7 and 8, which divide the light signal into two different pairs of mutually orthogonal linearly polarized components of the light signal, differing in angular orientation, allows us to obtain information about the state of polarization of the light signal in the fiber, that is, the magnitude of the shift of the "operating point".

The light signal from the outputs of two polarization dividers 7 and 8 enters through the optical fiber into the photodetectors of optical radiation. It forms four analog electrical signals that are fed to separate analog-to-digital converters 17-20. In analog-to-digital converters 17-20, the analog signal is converted into a digital code, which is supplied to the microcontroller 21. In the microcontroller 21, the digital code is processed, and data is stored. The presence of the communication node 22 allows you to upgrade the operation of the information-measuring system, updating the software of the microcontroller, and also serves to connect the system to other devices via a digital interface.

Thus, the proposed information-measuring system for measuring and monitoring electric current differs from similar systems in its expanded functionality, which consists in the possibility of storing the measurement results, if necessary, updating the microcontroller software and the possibility of pairing the sensor with external devices via analog and digital outputs. The presence of a microcontroller containing an information processing unit allows to increase the accuracy of measurements by correcting errors arising from the influence of the material of the optical fiber on the Verde constant, fluctuations in the ambient temperature and the wavelength of optical radiation.

Claims (1)

Information-measuring system for measuring and monitoring electric current, containing a series-connected optical radiation source in the form of a laser or a laser diode, a polarizer, a phase plate, polarization-preserving optical fiber with linear birefringence, rolled into a coil, inside of which there is a current conductor, a divider optical fibers, polarization dividers, optical radiation photodetector, characterized in that as optical radiation photodetectors with Exit divisors used polarized photodiodes electrically connected with amplifiers and analog-to-digital converters, the outputs of which are connected to the microcontroller comprising information processing unit and the communication node.