Device for reducing electromagnetic influences on the communication line

 

(57) Abstract:

The invention relates to equipment of electrified Railways. The device contains a sensor of harmonic components of the traction current and the node signal processing with n-tier unit of the phase-shifting elements connected information inputs to the corresponding outputs of the selector traction current, and control inputs to the respective outputs of the first n-tier unit controls the phase shift of the first n-tier unit scale amplifiers with scaling factors Km(comp), inputs connected to respective outputs of the first block of the phase-shifting elements, and a mixer. The device also includes an adjustable current source that is associated managing input to an output of the mixer and is included in rassechku grounded at both ends of the shielding wire located between the contact network and the affected line. In contrast to the known device is provided with a feedback channel with a sensor of harmonic components of the compensating current shielding wire, the second n-tier selector compensating current, a n-tier unit controls the phase shift of the second n-tier unit of the phase-shifting elements and in which astaburuaga blocks for large-scale amplifiers selected in accordance with the ratio Km(comp)-Km(OS)= 1. The device provides a high protective effect, which is achieved in any extended range current harmonic of the contact network by generating a compensating current through a negative feedback on the parameters of the compensating current. 2 Il.

The device relates to the field of electrified Railways and can be used to reduce the influence of electrical traction network for interconnecting communication lines.

As you know, the traction network as a single-wire line with a return current through the ground, almost completely unbalanced. As a result, the currents flowing in traction network of Railways, electrified as on the AC system, and the system constant, have a disturbing effect on the adjacent air and cable communication lines, radio, remote control and so on, Existing methods of reducing the effects are divided into passive and active [1]. It is also known that interference in the communication lines due to magnetic influence, and electromagnetic processes in traction network, determined by the higher harmonic components of the spectrum of the traction current.

A device for reducing electromagnetic influences on adjacent lines of communication with electro network and the communication line, which is induced by electromagnetic interference from higher harmonics traction current flowing through the contact network. In the device there is also a level sensor noise, the equivalent line, the interference selector, the controller gain, inverting amplifier, an adjustable current source and protective shielding wire.

Feature selectors of this device is that they lock the lower harmonics (first, third, fifth), no significant interfering influence on the communication line, and ignore the higher harmonics (seventh and above), i.e., are high-pass filters.

The signal at the output of the selector traction current, which is the amount of higher harmonics traction current, is compared by the controller gain to the signal at the output of the selector interference, which is a sum of harmonics interference in the communication line. If the compared signals are not equal, then the output of the regulator gain is generated the error signal representing a DC voltage whose value is proportional to the error signal. The amplifier shifts the amount of harmonic components 180 El. degrees and changes its amplitude depending the phase relative to the traction current) is supplied in a protective shielding wire. Thus, the total electromagnetic field of higher harmonics from the traction current in the contact network and the current in the shielding wire is reduced, which reduces the noise level in the communication line.

Thus, this device performs compensation of the inductive influence of higher harmonics traction current due to change (control) the amplitude of the signal in a protective shielding wire.

The known device is the analog has the following disadvantages.

1. The principle of the device is based on the fact that the signal from the traction current in the selector traction current is allocated only the amount of harmonics that have the greatest Psophometric impact. Then, the signal thus obtained, is amplified in an inverting amplifier to the required size and then have to be shifted in phase by 180 El.degrees with respect to the current contact network.

It is known, however [3] that the gain of the amplifier when changing the frequency of the signal varies according to the module, so the individual harmonic components of the signal applied to the input of the amplifier, amplify them different and move at different angle. These factors lead to a distortion of the output waveform. The result is it inverse.

2. It is known that the shielding wire has a distributed active-reactive impedance, which defines it as the line frequency phase and amplitude-frequency dependence. As is known, the reactance with increasing frequency is changed, therefore, each harmonic flowing in the shielding wire through the amplifier, is shifted in phase and change in amplitude. This leads to the fact that the shape of the signal in shielding the wire does not match the shape of the signal in the contact network, and the angle between the signals is different from 180 El.degrees.

3. It is also known [4] that the current transformer that is used as a sensor traction current has a non-linear frequency and phase dependence, and thus introduces an additional phase shift in the signal to be amplified.

The described device is similar fully performs its function (ensures the flow in the shielding wire of this current, in which the content and the amplitude of the higher harmonics corresponds to the current contact network, and their phases are shifted by 180 El.degrees relative to an equivalent harmonic current contact network) only if the device itself, i.e., the inverting amplifier circuit shielding wire is ground, the sensor t the e l e C the circuit wire-to-ground sensor traction current such distortions contribute, so the protective effect device similar to this worsens the stronger, the more delivered by the device capacity.

Experiments have shown, the device is similar to an effective protective properties in the presence of traction current harmonics up to 9-11, inclusive. At the same time, in [5] indicated that the impact (Psophometric) the influence of higher harmonics extends to 41, inclusive, and under the new rules until the 67th inclusive.

In these conditions (in this range) distortion of the amplitude and phase of the harmonics introduced by the amplifier circuit shielding wire is ground, the sensor traction current, significantly reduce the protective effect device similar to the above-mentioned reasons.

As a prototype made a device for reducing electromagnetic influences on the communication line.with. 1678664, BI 1991, 35).

It contains a sensor traction current, located on the influence of the contact network, the node signal processing, an adjustable current source. Host signal processing consists of a selector traction current, phase-shifting block, the block scale amplifiers, mixer and block controls the phase shift. Moreover, these is athelny filters, each of which is configured strictly on a certain harmonic. The total number of such filters is equal to the number of compensated harmonics.

The device operates as follows.

The current in the contact network creates an electromagnetic field, the higher harmonics which bring in line electromagnetic interference. The current sensor transforms and outputs a signal corresponding to the form of the current in the traction network.

From him the selector traction current allocates the higher harmonics, which have an electromagnetic effect on the communication line. Each selected harmonic is shifted in phase by the phase-shifting unit and is formed by amplitude in the block scale amplifiers. The resulting signal through an adjustable current source is supplied in a protective shielding wire, the last creating around its electromagnetic field. The peculiarity of the resulting signal is that the amplitudes of all harmonics correspond to the amplitudes of the harmonic current of the contact network, and their phases are opposite. In the electromagnetic fields of these harmonics in the contact network and the wire are offset and interference in the communication line is reduced to any originally specified level.

Structural schema >/P>The interference signal associated with the control and disturbance impacts the following relationship: X=F(U,Z)

Scheme (see Fig.1) reflects the principle of open governance. The absence in the block circuit diagram of the master program also provides this principle, if the algorithm of functioning of the device is laid when designing the system. When designing a device prototype, knowing the amplitude and phase errors introduced by the various elements of the device prototype, you can make schema correction factors for these errors. Thus, the device is a prototype built on the principle of open governance.

The essence of the principle is that the control algorithm is developed only on the basis of a given algorithm operation, and therefore is not controlled by other factors, such as disturbance and output coordinates of the process. The signal flow in all elements of the system device-prototype - protected line is in one direction from input to output.

A disadvantage of the known device the prototype is that it does not provide the required level of noise suppression. This is due to the fact that the device-ol the parameters of the circuit protective conductor - earth, this leads to the danger of neocomposite or overcompensation. So it is in such critical conditions, the device stops responding to its primary function: reduction of electromagnetic effects on adjacent traction network communication lines.

The problem solved by the invention, the enhancement of protective actions related with traction network communication line by generating a compensating current through a negative feedback on the parameters of the compensating field.

The inventive device differs from the prototype in that the feedback generated by the parameters of the compensating field, stabilize the compensation mode when external impacts and failures of the device.

The inventive device (Fig. 2) contains the sensor 2, located between influencing suspension and reverse wire connected by its output to the input of the selector traction current, the processing unit signal, the feedback channel 10. Thus the output of each electoral filter selector affecting current 4 is connected with the corresponding information input of each of the phase-shifting block elements 5 of the first unit of the phase-shifting elements. To each of the control inputs of the first block of the phase-shifting elements connecting the moving block elements 5 are connected to the appropriate input scale amplifier of the first block large-scale amplifiers 7. The outputs of all large-scale amplifier unit 7 is connected to a part of the inputs of the mixer 8, the second part of the inputs of which are connected the outputs of all large-scale amplifiers of the second unit of the large-scale amplifiers 15. The second block of the phase-shifting elements 13, the second circuit controls the phase shifter 14, the second block of the large-scale amplifiers 15 and the sensor 11 harmonic components of the compensating current shielding wire 16 and the connections between them are identical to the blocks 5, 6, 7, 2, respectively. The output of mixer 8 is connected with the control input of the controlled current source 9, is included in rassechku at one end of the shielding wire 15, grounded at both ends and located between the contact network 1 and is affected by the line 16.

Compared with the device-the prototype of the proposed device further comprises a functional chain, consisting of blocks 11, 12, 13, 14 and 15. These blocks form a channel of negative feedback on the parameters of the compensating current in the reverse wire, stabilizing the operation of the device for its sustainability.

The device operates as follows. The sensor of harmonic components affecting current contact network 2, located between the contact network and the th interferer current contact network. From the signal thus obtained, the selector 3 selects the higher harmonic components that have the greatest Psophometric impact on the line 16. Each selected harmonic is adjusted in phase and amplitude in units 5 and 7, respectively.

The second sensor 11 signal, which compensate proportional to the current in the reverse wire, transformed and fed into the block 12, where it is separated from interference and is divided into harmonic components, which are adjusted in phase and amplitude in blocks 13, 14, 15.

The specialty of the inventive device is that in the absence of any disturbances in the operation of the device and in the absence of external factors causing such violations, the feedback channel formed by the blocks 11, 12, 13, 14, 15, 't work. This is achieved by the appropriate selection of phase and gain in blocks 13, 14 and 15. However, in case of violation in the operation of the device the error signal received from the output device to the adder 8 with the opposite sign, which will cause a decrease. Thus, the operation of the device is stabilized by the negative feedback.

The positive effect compared with the device of the prototype is to increase saktay network.

Sources of information

1. K, Marquardt's. The supply of electric Railways. M.: Transport, 1965, S. 445-446.

2. A. C. 1400922, BI 21, 1988, M CL 4 60 M 3/00.

3. Tsykin, C. Amplifiers electrical signals. Moscow-Leningrad. State energy publishing house, 1962, C. 19-20.

4. Bulychev, A. C. and Vanin Century as the Study of the frequency characteristics of the current transformer. Minsk. News of higher educational institutions of the Ministry of higher and secondary education of the USSR. Energy 1987.

5. Rules are sewn devices wired and wired broadcasting from the influences of traction network of electric Railways AC. M.: Transport, 1973.

Device for active noise reduction in the lines adjacent to electrified areas containing the sensor of harmonic components of the traction current, located on the influence of the contact network, the node signal processing with n-tier unit of the phase-shifting elements connected information inputs to the corresponding outputs of the selector traction current, and control inputs to the respective outputs of the first n-tier unit controls the phase shift of the first n-tier unit scale amplifiers coefficie the elements, and a mixer connected to the first group of inputs to the corresponding outputs of the first block large-scale amplifiers, an adjustable current source that is associated managing input to an output of the mixer and is included in rassechku grounded at both ends of the shielding wire located between the contact network and the affected line, characterized in that it is provided with a feedback channel with a sensor of harmonic components of the compensating current shielding wire, a n-tier selector compensating current, the second n-tier unit controls the phase shift, the second n-tier unit of the phase-shifting elements and the second n-tier unit scale amplifiers with scaling factors Km(OS), while the sensor of harmonic components of the compensating current and the selector compensating current are connected in series, the outputs of the selector compensating current and the second unit controls the phase shift is connected to the corresponding inputs of the second unit of the phase-shifting elements whose outputs through the second block of the large-scale amplifiers connected to corresponding inputs of the second group of inputs of the mixer, and the scaling factors in blocks of large-scale amplifiers selected in soo

 

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