SU1396199A1 - Device for relay protection of electric unit - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to ensure that the protection is working and that the noise immunity of the communication channels is improved. The purpose of the invention is achieved in that the measuring part of the protection installed on the phase conductors of the protected electrical installation (elements 2-5) and connected to the executive part by the radio channel, additionally introduces a current sensor 1, made on the permalloy core, which generates roll signals when passing through the protected connection of load currents. And in the executive part of the protection (elements 6 and 7), a signal processing algorithm with an operator for signal detection is also used, which ensures high noise immunity of protection. 1 il. with $ (L

Description

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The invention relates to relay protection and can be used to protect electrical installations of power systems with control of channel health where access to them is impossible under the operating conditions.

The aim of the invention is to ensure that the protection is working properly.

The drawing shows the functional scheme of the device.

The device consists of a control pulse sensor 1 and two current sensors 2 connected to a unit 3 for summing input signals connected in series to a pulse shaping unit 4, a signal transmission unit 5, a signal receiving unit 6 and an actuator 7.

The device works as follows:

Sensor 1 is connected via a block 3, the summation of the input signals with datacam 2 is consistent and sequential), i.a sensors 2 are interconnected by JBCTpeMHO. As a result, in the normal | mode, from each phase operating current in sensor 1, after each 10 ms, a signal appears that, having passed through block 3: 9-Ummir of the input signals and the block and forming pulses, unit 5 transmits: Signal reduction, wireless channel and to the entire receiving device 6, 7,: it signals the health of the device as a whole with the help of the LED.

In the event of a short circuit, a circulating current arises in the sensor 2 electrical device 2, which leads to the appearance of a working signal. The work signal, which is summed up by the scroll signal in the summation block of the input signals, goes to the pulse shaping unit 4. The signal transmission unit 5 converts the working signal into a packet of amplitude-modulated pulses, which, unlike the analog signal, has a significant detuning from interference,

The device provides disconnection of the electrical installation from the power source; 0 for 20 ms.

Sensors 1 and 2 are low-power saturating current transformers (NTT), the primary windings of which are phase conductors, and the secondary windings are connected to unit 3 Summing of input signals. They not only fulfill the functions of the source No. 1, but also are the source

power supply for the transmission part of the protection installed at the high-voltage potential. Each of the sensors 1 and 2 has its own magnetic core, which is a spiral ribbon torus. The magnetic core of sensor 1 is made of permallo MO - perminvar SANSHP With a coefficient of square, 99, and sensor 2 is made of electrical steel E34 14. Constructively between themselves, sensors 1 and 2 differ in not only the magnetic conductor, but also the number of turns. These conditions allow the formation of EMF of mutual induction on the secondary windings of the NTT in the form of pulses that appear at the output of sensor 1 every 10 ms at the operating current in the phases and are called a control signal. Only in emergency mode (for any kind of short circuit), the secondary windings of sensors 2 will receive a pulse, called an operating signal, every 10 ms.

The difference in the materials of the magnetic conductors and the switching scheme causes a significant difference in the working signals from the control signals in terms of their duration. The presence of the control signal provides a check of the protection performance when the operating current of the load flows. To improve the quality of the communication channel, the working signal is converted as a code group. For this purpose, from the output of block 3, the summation of the input signals where a two-half-period rectification is applied to increase noise immunity, the signal goes to block 4 of the pulse former. Then, the signal is limited and stabilized by the voltage level, which makes it possible to increase the reliability and the insulating quality of the radio elements.

Direct conversion of the signal to the code group is carried out in block 5, consisting of a discharge-charge circuit and an electronic key

The discharge of capacitance C to the oscillating circuit is accompanied by the appearance in the latter of damped high-frequency oscillations. Thus, changing the parameters of the shock excitation circuit and the constant charge D, we obtain a given code group of a signal with a certain high-frequency filling, the energy of which is converted by the antenna into the energy of electromagnetic waves, which allows the code group to be transmitted over a communication channel for a small distance. The energy of electromagnetic waves is converted by the antenna of the receiving part of the protection located on the ground potential, and the high-frequency oscillations corresponding to the law of time variation of the transmitted signal.

The duration of the working signal is an order of magnitude longer than the control signal; its summation with the working signal does not cause a distortion of the working signal and does not impair the noise immunity conditions of the transmitted signal. At the same time, having a control signal, you can always judge the health of the entire device.

Claims (1)

Invention Formula A device for relay protection of an electrical installation, containing two sets of current sensors with primary windings for connection to a controlled circuit, a signal transmission unit, a signal receiving unit and an actuator connected to it, characterized in that, in order to monitor the health of the protection, an additional sensor is introduced ToKa with leads for connection to a controlled circuit with a core having a rectangular magnetization characteristic, a summation unit, a pulse shaping unit, and the secondary windings are The current sensors are connected according to the current difference circuit and one of these secondary windings is connected to the first input of the summation unit, and the other is connected to the first output of the secondary winding of an additional current sensor, the second output of which is connected to the second input of the summation unit, and the summation unit via a pulse shaping unit connected to a signal transmission unit.