Compensator of interference in received harmonic signal

Abstract

FIELD: railway technologies.SUBSTANCE: invention relates to a device for compensating for interference in signal receivers in track circuits. The interference compensator in the received harmonic signal comprises two voltage amplifiers, a three-winding transformer with two counter-connected input windings with the same number of turns and an output winding connected to the signal receiver, as well as a notch filter that does not pass the signal current, a power amplifier with an adjustable gain factor, and a band-pass filter. The notch filter is made in the form of an inductor and a capacitor connected in parallel. The band-pass filter is made in the form of a series-connected inductor coil and capacitor with nominal values as in a rejection filter. One input winding of the transformer is connected to the input of the compensator through a series-connected notch filter, voltage amplifier, band-pass filter and power amplifier with adjustable gain. The second input winding of the transformer is connected directly to the compensator input.EFFECT: increasing the noise immunity of the operation of signal receivers in track circuits, in automatic locomotive signalling or in systems for automatic control and monitoring of the state of elements of track lines.1 cl, 1 dwg

Description

[0001] Field of technology to which the invention relates

[0002] The invention relates to the field of railway automation and telemechanics and ensures increased noise immunity of signal receivers in systems for interval control of train movement or in systems for automatic control and monitoring of the state of elements of rail lines by compensating for interference in the received signal.

[0003] The invention can also find application in technical systems where harmonic signals subject to interference are used as useful signals.

[0004] State of the art

[0005] Signal currents transmitted along rail lines are subject to harmonic and pulsed interference from various sources. The signal receiver circuits in these devices include filtering or compensation for interfering interference [1,2]. The attenuation quality of passive filters assembled on resonant LC circuits implemented with inductors and capacitors is insufficient, leading to relatively frequent malfunctions of the signal receivers. The use of active filters is limited by the difficulty of eliminating dangerous failures. Passive filters in compensators cause phase changes in the interference, which degrades the degree of interference suppression.

[0006] A known device for compensating for interference is connected to the input of a receiver of signals from rail lines and containing a notch filter that suppresses the signal voltage, made in the form of an inductor and a capacitor connected in parallel; a three-winding transformer, the input windings of which have the same number of turns and are connected in accordance with, and its output winding is connected to the signal receiver, equipped with a second transformer designed to change the phase of the filter output voltage by 180 degrees [3]. However, this does not take into account the different degrees of attenuation of interference signals and changes in their phases by the notch filter depending on the frequency of these signals, which degrades the quality of interference suppression.

[0007] Also known is a device for compensating for interference in a track circuit receiver or automatic locomotive signaling system, connected to its input, equipped with a notch filter, two variable resistors and a circuit consisting of a switch, an inductor and a capacitor, as well as a three-winding transformer, in which two primary windings connected in opposite directions have the same number of turns, and a signal receiver [4]. This device was chosen as the closest analogue. However, the quality of interference suppression by this device is limited due to the mutual interfering influence of the notch filter and phase corrector signals assembled on passive elements, and also by the fact that it provides an increase in the quality of compensation only for those interferences whose frequency is either lower or higher than the frequency of the signal current, depending on the position of the switch.

[0008] Disclosure of invention

[0009] The technical result consists in increasing the noise immunity of the operation of signal receivers in track circuits, in automatic locomotive signaling or in systems for automatic control and monitoring of the state of elements of track lines.

[0010] The objective of the invention is to increase the noise immunity of signal receivers in track circuits, in automatic locomotive signaling systems, as well as in automatic control and monitoring systems for the state of rail line elements by increasing the degree of attenuation of harmonic and impulse interference from various sources by reducing the negative impact of the phase shift of interference signals by a rejection filter on the degree of their compensation, as well as eliminating the interfering mutual influence of a bandpass filter and the input winding of a transformer.

[0011] The task is achieved by proposing a compensator for pulse and harmonic interference of various frequencies in low-frequency signals transmitted along rail lines by track circuits, automatic locomotive signaling or automatic control and monitoring systems for the state of elements of rail lines, containing a three-winding transformer with two oppositely connected input windings having the same number of turns, connected to a signal receiver by an output winding, as well as a rejection filter that does not pass the signal current, made in the form of an inductance coil and a capacitor connected in parallel;and a voltage amplifier additionally equipped with a power amplifier with an adjustable gain factor, a bandpass filter that passes only the signal current and is made in the form of a series-connected inductor coil and capacitor, the nominal values ​​of which are the same as in the rejection filter, wherein the input voltage of the compensator is supplied to one input winding of the transformer through a series-connected rejection filter, voltage amplifier, bandpass filter and power amplifier with an adjustable gain factor.

[0012] As a result, both harmonic signals and interference pulses are fed to the transformer input windings in antiphase, thereby compensating for these interferences. The frequency selectivity of a series circuit is identical to that of a parallel circuit when the parameters of the circuit elements are identical [5, 6]. Therefore, the phase and amplitude changes of various interferences by resonant bandpass and rejection filters, assembled on capacitors and inductors with the same nominal values, are both oppositely and identically directed. This ensures phase equality of the interference signals on the transformer input windings, thereby increasing the degree of suppression of harmonic or impulse interference, and reducing the interference levels in the signal receiver to values ​​close to zero.

[0013] Brief description of drawings

[0014] The drawing figure shows the block diagram of the interference compensator.

[0015] Implementation of the invention

[0016] The device comprises a three-winding transformer 1, to the output of which a signal receiver 2 is connected. The first input winding 3 of the three-winding transformer 1 is connected directly to the input of the compensator. The second input winding 4 of the three-winding transformer 1, having the same number of turns and connected in opposite directions with its first winding 3, is connected to the input of the compensator through a series-connected rejection filter that does not pass the signal current and is made in the form of a first inductor 5 and a first capacitor 6 connected in parallel, through a voltage amplifier 7 and a bandpass filter that passes only the current of the useful signal and is made in the form of a second capacitor 8 and a second inductor 9 connected in series, as well as a power amplifier 10 with an adjustable gain. The nominal values ​​of the first and second inductors 5 and 9 are the same. The nominal values ​​of the first and second capacitors 6 and 8 are also the same.The device works as follows:.

[0017] The input signal of the compensator, taken from the track circuit at the location where the signal receiver is installed, from the receiving locomotive coils of the automatic locomotive signaling system or from the output of the communication line of the automatic control and monitoring system for the condition of rail line elements, containing the sum of the voltages of the useful signal and interference signals , is fed to the first input winding 3 of the three-winding transformer 1 directly, to the output of which the signal receiver 2 is connected. The input signal of the compensator is fed to the second input winding 4 of the transformer 1 through a series-connected rejection filter, constructed according to a circuit from the first inductor 5 and the first capacitor 6 connected in parallel, a voltage amplifier 7, through a resonant bandpass filter, including a second capacitor 8 and a second inductor 9 connected in series, and also through a power amplifier 10 with an adjustable gain. The first and second input windings 3 and 4 of the three-winding transformer 1 have the same number of turns and are connected in opposite directions. As a result, the signal voltage on the output winding of the transformer 1, equal to the difference in the signals on its first and second input windings 3 and 4, will be equal to the voltage of the useful signal .

[0018] Both notch and band-pass filters reduce the amplitude of interference signals due to power loss and distort the phase of these signals. The input impedance of filters built on circuits of parallel or series-connected capacitors and inductors is purely resistive at the resonant frequency of the useful signal.

[0019] When a capacitor and an inductor are connected in parallel at frequencies below the resonant frequency, the filter resistances have a resistive-capacitive nature, and as a result, the phase of the interference signal is shifted by the filters by an amount from zero to - π / 2 as the frequency decreases. At interference frequencies above the resonant frequency, the filter resistances have a resistive-inductive nature, therefore, the phase of such interference signals is shifted by the filters by an amount from zero to + π / 2 as their frequency increases [5, 6].

[0020] When a capacitor and an inductor are connected in series at frequencies below the resonant frequency, the filter resistances have a resistive-inductive nature, and as a result, the phase of the interference signal is shifted by the filters by an amount from zero to π / 2 as the signal frequency decreases. At interference frequencies above the resonant frequency, the filter resistances have a resistive-capacitive nature, therefore, the phase of such interference signals is shifted by the filters by an amount from zero to -π / 2 as their frequency increases [5, 6].

[0021] When interference signals pass sequentially through these parallel and series resonant circuits, assembled using capacitors and inductors of identical nominal values, the phase changes at the interference frequency are mutually compensated by the filters. This ensures almost complete compensation of the interference effects. Some error in the compensator's operation may arise due to inaccurate circuit adjustment.

[0022] This results in increased attenuation of interference from traction current, power lines, and other sources on track circuit receivers, automatic locomotive signaling systems, or automatic control and monitoring systems for track components. Nearly complete interference compensation, limited only by the quality of filter settings, reduces the number of failures in the operation of these signal receivers. This improves train safety and reduces losses in train operations due to a reduction in the occurrence of false signals on ground or locomotive signals requiring a reduction in train speed, or improves the reliability of information received from automatic control and monitoring systems for track components.

[0023] Laboratory tests of the compensator prototype confirmed that interference was completely compensated for with a signal current frequency of 25 Hz. Interference suppression at higher signal frequencies was nearly complete. Similar results were obtained with other useful signal frequencies.

[0024] Sources of information

[0025] 1. Soroko V.I., Rosenberg E.N. Equipment of railway automation and telemechanics: Handbook: in 2 books. Book 2. - M .: NPF "PLANETA", 2000.- 1008 p.

[0026] 2. Shamanov V.I. Interference on track circuit equipment and automatic locomotive signaling. Protective equipment. - M .: Federal State Budgetary Educational Institution of Additional Professional Education "Training and Methodological Center for Education in Railway Transport", 2019. - 303 p.

[0027] 3. Shamanov V.I., Denezhkin D.V. Noise compensator in a harmonic low-frequency signal. Russian Federation Patent No. 2754372 of the Russian Federation dated September 1, 2021.

[0028] 4. Shamanov V.I., Denezhkin D.V. Compensator for harmonic interference from traction current. Russian Federation Patent No. 2823641 dated July 26, 2024.

[0029] 5. Bakalov V.A., Dmitrikov V.F., Kruk B.I. Fundamentals of circuit theory. - M.: Goryachaya Liniya - Telecom. 2007. - 596 p.

[0030] 6. Novikov Yu.N. Basic concepts and laws of circuit theory, methods of analyzing processes in circuits. - St. Petersburg: Lan, 2011. - 368 p.

Claims

A compensator for interference in a received harmonic signal, comprising two voltage amplifiers, a three-winding transformer with two back-to-back input windings with the same number of turns and connected by an output winding to a signal receiver, as well as a rejection filter which does not pass the signal current and is made in the form of an inductance coil and a capacitor connected in parallel, characterized in that it is equipped with a power amplifier with an adjustable gain factor, a bandpass filter which passes only the signal current and is made in the form of an inductance coil and a capacitor connected in series with nominal values ​​​​as in the rejection filter, wherein the input voltage of the compensator is supplied to one input winding of the transformer through a series-connected rejection filter, a voltage amplifier, a bandpass filter and a power amplifier with an adjustable gain factor, and the input voltage of the compensator is supplied directly to its second input winding.

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