RU117014U1 - SENSOR FOR HIGH VOLTAGE LINES - Google Patents

Abstract

A current sensor for high-voltage transmission lines of alternating voltage, containing a ferrite loop surrounding a current-carrying wire, with a coil of copper wire having a tap at a tenth of the turns, characterized in that the output ends of the coil and tap are connected to voltage converters into optical pulses of the infrared range with a repetition rate , proportional to the current in the current-carrying wire, and at a distance of 5 ... 10 m there are photoreceiving units with focusing lenses, selective filters and modules for converting optical pulses into electrical ones with simultaneous amplification and frequency inversion into a digital binary code, and converters into optical pulses connected to the ends of the coil and to the tap have different emission wavelengths and pulse repetition rates.

Description

The utility model relates to electrical engineering and is intended, in particular, for measuring the average currents in high voltage AC power lines.

Utility Model Description

Known electromagnetic measuring current transducers RU 2006043 C1, 01/15/1994; RU 2079848 C1, 05/20/1997, for measuring without breaking an electric circuit with a transforming transformer (Rogowski belt). Also known is a current meter RU 2079848 C1, 05/20/1997 with a Rogowski belt, containing a winding placed in a frame having an integrating operational amplifier.

The device described in patent RU 2133473 C1, from 06.01.98, cl. G01R 19/00, adopted as a prototype, contains a ferromagnetic belt surrounding the current-carrying wire, contains two windings, and compensating voltage is applied to the second winding.

The disadvantages of the prototype include the need to use additional compensating voltage. To supply it to a high-voltage line (from 6 to 500 kV), additional ceramic insulators are required to increase the insulation between and the receiving measuring equipment and the line. The weight of the insulators and their cost increase in proportion to the line voltage. If for a line with a voltage of 6 kV the weight of insulators and capacitors is 5 ... 6 kg, then for a line of 36 kV it is 20 ... 30 kg, and for a line of 500 kV it is 200 ... 300 kg. Accordingly, the cost of current sensors increases. which prevents the widespread use of the prototype as a device for measuring currents in high voltage networks.

The essence of the model is the use of a converter of the measured current into light pulses, the repetition rate of which is proportional to the current strength, and the receiving equipment is located at a distance of 5 ... 10 m from the high voltage line, which leads to its complete isolation from high voltage.

The technical result consists in the complete isolation of the high voltage from the low voltage part of the equipment and the data network. At the same time, the weight and cost of the equipment are reduced, and at the same time, the noise immunity of the channel for remote transmission of current measurement data over long distances is increased.

The specified technical result is achieved by the fact that the sensor device uses a ferrite circuit located on a high-voltage current-carrying wire, with a coil of two hundred turns of copper wire with a tap from the 20th coil, and voltage converters to optical pulses of infrared are connected to the output ends of the coil and to the tap range with a repetition rate proportional to the current strength in the current-carrying wire, and at a distance of 5 ... 10 m there are photodetector devices that convert optical pulses to electrical ones TERM gain and frequency inversion in the digital binary code for telemetric transmission of measurement results over long distances. In this case, the transducers connected to the ends and tap of the coil have different radiation wavelengths.

The structural diagram of the proposed model of the current meter is presented in figure 1. In the diagram of FIG. 1, the following notation is adopted: high-voltage current-carrying wire 1 is surrounded by a ferrite circuit 2, on which there is a coil with N turns of copper wire 3; the voltage removed from the coil is supplied to the converter in optical pulses 4 with a radiation wavelength λ ₁ , the frequency of which is proportional to the current strength; a converter 4 is connected via an optical transmission channel 5 to a photodetector 6 with an optical filter and an amplifier; then follows a pulse counter 7 with a converter into a serial digital code for a telemetric data transmission channel over a long distance along channel 8. To increase the measurement range, the device provides a tap from the 20th turn of coil 9, which is also connected to the device for converting to optical pulses for 10 s different repetition rate and with a different radiation wavelength λ ₂ forming the optical communication channel 11 with the photodetector 12.

The device operates as follows.

The current passing through the high-voltage current-carrying wire 1 creates an alternating magnetic field that acts on the ferromagnetic circuit 2 and excites the voltage in the coil of copper wire 3 with 200 turns. The voltage from the coil is proportional to the current strength in the current-carrying wire 1 is supplied to the Converter 4, where the aforementioned current is converted into optical pulses at a wavelength of λ ₁ with a pulse repetition rate proportional to the current strength. Optical pulses through the optical air transmission channel 5 enter the photodetector 6, with a focusing element and a selective filter that transmits a wavelength of λ ₁ .

In block 6, optical pulses are converted into electrical pulses and amplified to a voltage of 4 ... 5 V. The resulting electrical pulses go to a pulse counter 7, are converted into serial digital codes that enter telemetry channel 8 for transmitting data over a long distance to a computer control room, where they can be used in the database or for the formation of readings of panel meters.

With strong currents in the high-voltage transmission line 1, the pulse shaper at a wavelength of λ _{1 is} blocked by a zener diode and the converter 10 starts to work from the tap from the 20th turn of coil 9 to measure strong currents. The converter of high currents 10 generates optical pulses at a wavelength of λ ₂ with a frequency proportional to one tenth of the current strength, which through the optical channel 11, at a wavelength of λ ₂ , enter the photodetector block 12 with an optical filter that transmits wavelength λ ₂ and an amplifier. Electrical pulses from block 12 with a coding symbol go to a pulse counter 7 with a converter into serial digital codes for a telemetric data transmission channel over a long distance 8, adjusted for tenfold significance.

The device and the principle of operation of the photodetector blocks 6 and 12 (Fig. 1) is illustrated by the structural diagram in Fig. 2, where the following notation is given: λ ₁ and λ ₂ are optical pulse signals from converters 4 and 10 (Fig. 1) at the corresponding wavelengths arriving at the focusing lenses 13, behind which there are filters 14, followed by photodiodes with amplifiers 15, the electrical pulses from which are fed to a binary pulse counter 7 with a converter into a serial digital code supplied to a telemetric data transmission channel over a long distance 8.

Application examples

The proposed device was tested on a stand with current conductors up to 10 kV and showed the ability to measure the average current from 0.1 to 100 A with an accuracy of 0.2%. The number of turns in coil 3 was 200 and tap 9 was on the 20th turn. The distance of the air optical channel varied from 5 to 10 m without deterioration of measurement accuracy. Optical channels were selected at wavelengths of 0.85 and 0.98 μm. Specially selected germanium interference filters made it possible to clearly separate the selected channels and to exclude the influence of sunlight on the optical transmission channels of pulses.

During the tests, the effect of external electromagnetic interference on the transmission channel was investigated. Studies have shown that fluctuations in the electromagnetic field of intensity up to 10 V / cm with a frequency of 50 Hz do not affect the readings of the device.

Comparative characteristics of the known and proposed current meter are shown in table 1. According to the data of table 1, the proposed device exceeds the prototype in all respects.

Table 1. Comparative characteristics of the known and proposed current meter No pp Parameters and specifications Known device (prototype) Proposed device one Operating ranges for measuring current strength, A 0,1 ... 30 0,1 ... 300 2 Relative measurement accuracy,% 0.5 0.2 3 Type of transmission channel Bias currents Optic four The presence of additional insulation between the high-voltage line and low-voltage measuring equipment there is no 5 Weight of additional insulation, kg: at 6 kV 10 no 36 kV one hundred no 360 kV 800 no 6 Estimated cost of the meter current, thousand rubles: at 6 kV 6 3 36 kV 36 fifteen 360 kV 360 one hundred 7 Power consumption of equipment, W one hundred 10

Claims (1)

A current sensor for high voltage alternating voltage transmission lines containing a ferrite circuit surrounding a current-carrying wire, with a copper wire coil having a tap on a tenth of turns, characterized in that the output ends of the coil and tap are connected to voltage converters in infrared optical pulses with a repetition rate proportional to the current strength in the current-carrying wire, and at a distance of 5 ... 10 m there are photodetector units with focusing lenses, selective filters and conversion modules I have optical pulses into electric ones with simultaneous amplification and frequency inversion into digital binary code, and the converters into optical pulses connected to the ends of the coil and to the tap have different radiation wavelengths and pulse repetition rates.