CN104467921B - A kind of high speed power line carrier communication system signal distribution equipment - Google Patents

Abstract

The present invention provides a high-speed power line carrier communication system signal distribution device, including a carrier signal coupler, a first carrier signal modem, a second carrier signal modem, a first communication terminal and a second communication terminal, the first carrier signal modem Connected with the first communication terminal, the second carrier signal modem is connected with the second communication terminal, and also includes a signal distributor, the input end of the signal distributor is connected with the carrier signal coupler; the signal distributor It includes a first output terminal and a second output terminal, the first output terminal is connected with the first carrier signal modem, and the second output terminal is connected with the second carrier signal modem. The invention has the advantages of low cost and strong anti-interference ability.

Description

A high-speed power line carrier communication system signal distribution device

technical field

The invention provides a high-speed power line carrier communication device, and in particular relates to a high-speed power line carrier communication system signal distribution device with low cost and strong anti-interference ability.

Background technique

Power Line Carrier Communication (PowerLine Carrier-PLC) is a special communication method that uses power transmission lines as the information transmission medium for voice or data transmission. According to the power line voltage level for carrier signal transmission as an information transmission medium, it can be divided into: high voltage power line carrier communication (35kV and above voltage level), medium voltage power line carrier communication (10kV voltage level), low voltage power line carrier communication (380/220V low voltage distribution Wire); according to the signal modulation method, it can be divided into OFDM, FSK, PSK, ASK, etc., and according to the transmission rate, it can be divided into narrowband and broadband transmission. Generally, the power line carrier communication equipment is that the carrier communication terminal sends the information to be sent to the carrier signal modem in the form of a traditional digital signal. The carrier signal modem modulates the signal according to the preset modulation method and sends it to the carrier signal coupler. The carrier signal coupling The converter couples the modulated carrier signal (generally ranging from 100kHz to 40MHz) to the power line for transmission, and the signal receiving process is reversed. In this way, the entire set of equipment must have two carrier signal couplers to work, and the cost is very high, which is not conducive to popularization and application, and the anti-interference ability is poor.

Contents of the invention

In order to solve the above-mentioned problems, the present invention provides a signal distributor that only needs one carrier signal coupler to complete the work, and has low cost and strong anti-interference ability. A high-speed power line carrier communication system signal distribution device provided by the present invention adopts the following technical scheme:

A high-speed power line carrier communication system signal distribution device, comprising a carrier signal coupler, a first carrier signal modem, a second carrier signal modem, a first communication terminal and a second communication terminal, the first carrier signal modem is connected to the first communication terminal Connection, the second carrier signal modem is connected with the second communication terminal, and also includes: a signal distributor, the input terminal of the signal distributor is connected with the carrier signal coupler; the signal distributor includes a first output terminal and a second output terminal, The first output end is connected with the first carrier signal modem, and the second output end is connected with the second carrier signal modem.

A further feature is that the signal splitter also includes an LC bandpass filter, an impedance matching autotransformer, a distribution autotransformer, an isolation resistor, a first load resistor and a second load resistor, and the LC bandpass filter and the distribution autotransformer are respectively connected to The impedance matching autotransformer is connected, the first output terminal and the second output terminal are respectively connected with the distribution autotransformer, the isolation resistor is connected between the first output terminal and the second output terminal, and the first load resistance is connected to the first output terminal. terminals, and the second load resistor is connected to the second output terminal.

A further feature is that the signal distributor also includes a compensation capacitor, which is connected to the impedance matching autotransformer and the connection line between the distribution autotransformer.

A further feature is that the LC bandpass filter is composed of an LC filter network inductance and an LC filter network capacitor connected in series.

A further feature is that the resistance value of the first load resistor is equal to the resistance value of the second load resistor.

A further feature is that the resistance of the isolation resistor is twice the resistance of the first load resistor.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The present invention has a signal distributor, which distributes one power line carrier communication signal into two channels of carrier signals that will not interfere with each other, and realizes the normal communication of two power line carrier communication terminals through one carrier signal coupler. Therefore, the number of carrier signal couplers installed can be reduced, the system cost can be reduced, and the mutual interference of adjacent frequency signals can be improved.

2. The present invention has an LC band-pass filter, which can stabilize signals, reduce interference, and ensure stable signal transmission.

3. The present invention has a compensation capacitor, which compensates and distributes the autotransformer current, impedance matches the inductance of the connecting line between the autotransformers, and ensures the frequency characteristics.

4. The present invention has an isolation resistor, and the resistance of the isolation resistor is twice the resistance of the first load resistor and the second load resistor, so that the transmission signals at the two output terminals are independent of each other and unaffected, ensuring the stability of the transmission .

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is a circuit schematic diagram of a high-speed power line carrier communication system signal distribution device of the present invention;

Fig. 2 is a signal-to-noise ratio diagram of the first communication terminal in an embodiment of the high-speed power line carrier communication system signal distribution device of the present invention;

Fig. 3 is a signal-to-noise ratio diagram of a second communication terminal in an embodiment of a signal distribution device for a high-speed power line carrier communication system of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

As shown in Figure 1, a high-speed power line carrier communication system signal distribution device includes a carrier signal coupler 1, a first carrier signal modem 2, a second carrier signal modem 3, a first communication terminal 4 and a second communication terminal 5, The first carrier signal modem 2 is connected with the first communication terminal 4, the second carrier signal modem 3 is connected with the second communication terminal 5, and also includes a signal distributor 6, and the input terminal of the signal distributor 6 is connected with the carrier signal coupler 1 The signal distributor 6 includes a first output terminal 61 and a second output terminal 62, the first output terminal 61 is connected with the first carrier signal modem 2, and the second output terminal 62 is connected with the second carrier signal modem 3.

The preferred mode of the present invention is: signal distributor 6 also includes LC bandpass filter 63, impedance matching autotransformer 64, distribution autotransformer 65, isolation resistor 66, first load resistor 67 and second load resistor 68, LC The bandpass filter 63 and the distribution autotransformer 65 are respectively connected with the impedance matching autotransformer 64, the first output terminal 61 and the second output terminal 62 are respectively connected with the distribution autotransformer 65, and the isolation resistor 66 is connected with the first Between the output terminal 61 and the second output terminal 62 , the first load resistor 67 is connected to the first output terminal 61 , and the second load resistor 68 is connected to the second output terminal 62 .

The signal distributor 6 also includes a compensation capacitor 69 , which is connected to the connection line between the impedance matching autotransformer 64 and the distribution autotransformer 65 .

The LC bandpass filter 63 is composed of an LC filter network inductor 631 and an LC filter network capacitor 632 connected in series.

The resistance value of the first load resistor 67 is equal to the resistance value of the second load resistor 68 .

The resistance of the isolation resistor 66 is twice the resistance of the first load resistor 67 .

Example

Specifically, the carrier signal first passes through a 1-40MHz LC bandpass filter 63 composed of an LC filter network inductor 631 and an LC filter network capacitor 632 connected in series at the input end to filter out signals other than 1-40MHz, and then passes through the impedance The matching autotransformer 64 transmits the carrier signal to the distribution autotransformer 65 , and divides the carrier signal into two paths to the first output terminal 61 and the second output terminal 62 .

LC bandpass filter 63 design indexes are as follows in the present embodiment:

1) Center frequency: 20MHz;

2) -2dB bandwidth: ≥40MHz;

3) Insertion loss: ≤2dB;

4) Stop band suppression 1: f0±5MHz, suppression ≥ 40dB;

5) Stop band suppression 2: when f=24MHz, suppression ≥ 50dB;

6) Working temperature: -55℃～85℃;

7) Impedance: 50Ω.

The impedance matching autotransformer 64 is an impedance transformation transformer in this embodiment, which is wound on a ring-shaped high-frequency magnetic core. In this embodiment, the turns ratio between the input end and the tap to the ground is 1.414 to 1, The impedance ratio is 2 to 1, the center tap load is 25Ω, and the input impedance is 50Ω. Distribution autotransformer 65 is a distribution transformer in this embodiment, which is made by connecting the end of one enameled wire with the head end of another enameled wire as a center tap on the ring-shaped high-frequency magnetic core and winding several turns according to the transmission line principle , the impedance matching autotransformer 64 and the enameled wire of the distribution autotransformer 65 adopt the wire diameter according to the formula:

D＝1.13(I/J)^1/2

Calculated, I is the size of the current, J is the current density, and the calculated wire diameters are different for different values. Since the high-frequency current has a skin effect in the conductor, it is necessary to calculate the penetration depth of the conductor at different frequencies when determining the line length.

The impedance of the center taps of the impedance matching autotransformer 64 and the distribution autotransformer 65 is 50/2Ω, that is, 25Ω. According to the principle of the transmission line, the unfolded length of the coils of the impedance matching autotransformer 64 and the distribution autotransformer 65 should be much smaller than the wavelength, otherwise the high-frequency frequency response is unsatisfactory. If the unfolding length is short, the number of turns will inevitably decrease, and the inductance will also decrease, resulting in poor frequency response at low frequencies. Therefore, it is required that the magnetic permeability of the magnetic core should be high and the loss at high frequency should be small. Only in this way can the bandwidth of the distributor be guaranteed. In the present embodiment, the parameters of the selected impedance matching autotransformer 64 and distribution autotransformer 65 are as follows:

1) Application scope: coupling transformer

2) Type: Inductive magnetic beads

3) Winding form: inner winding

4) Inductance: 0.0046

The mutual isolation of the first output terminal 61 and the second output terminal 62 is realized by an isolation resistor 66 . If a signal is sent to the first output terminal 61, the signal flows to the impedance matching autotransformer 64 through the distribution autotransformer 65, and a reverse current is induced on the second output terminal 62 at the same time, but there is one and the first output terminal through the isolation resistor 66. The current of the same phase at the first output terminal 61 flows to the second output terminal 62, and the resistance value of the isolation resistor 66 is twice the resistance value of the first load resistor 67 and the second load resistor 68. These two currents are equal in magnitude and opposite in direction, and then cancel each other out. . The compensation capacitor 69 is used to compensate the inductance of the wiring between the distribution autotransformer 65 and the impedance matching autotransformer 64 to ensure frequency characteristics. The signal is sent from the center tap, and it is divided into two paths and flows to the first output terminal 61 and the second output terminal 62. Since the circuit is symmetrical, the power and phase of the two output signals are equal, and the two output terminals are respectively connected to 50 ohm first load resistor 67 and 50 ohm second load resistor 68. The signal sent by the input terminal is equally divided into the first output terminal 61 and the second output terminal 62, and half power is obtained on each output terminal, that is, a loss of 3dB. In fact, the loss of the wire and the magnetic core is added, and the total loss is about 4dB.

The final technical indicators of the signal distributor 6 are as follows:

(1) Frequency range: 1-40MHz;

(2) Reflection loss: ≤20dB;

(3) Insertion loss: ≤4.8dB;

(4) Stopband suppression 1: f0±5MHz, suppression ≥ 40dB;

(5) Stop band suppression 2: when f=24MHz, suppression ≥ 50dB;

(6) Mutual isolation: ≥30dB;

(7) Impedance: 50Ω.

As shown in Fig. 2 and Fig. 3, the signal-to-noise ratio graph of the high-speed power line carrier communication terminal of the first output end 61 and the second output end 62 of the present invention is actually measured on a 10kV overhead line with a length of 1.5 kilometers at a working frequency of 4-34MHz. Among them, the abscissa is the operating frequency, and the ordinate is the signal-to-noise ratio.

In addition, the above embodiments are mainly designed for high-speed power line carrier communication of 1-40MHz. If the parameters of LC filter network inductance, LC filter network capacitance, impedance matching autotransformer, distribution autotransformer, and isolation resistance are adjusted, the The invention patent is also applicable to other power line carrier communication.

The present invention has a signal distributor, which distributes one path of power line carrier communication signal into two paths of carrier signals that do not interfere with each other, and realizes that one carrier signal coupler can ensure the normal communication of two power line carrier communication terminals, thereby achieving The installation quantity of the carrier signal coupler is reduced, the system cost is reduced, and the mutual interference effect of adjacent frequency signals is improved.

The invention has an LC band-pass filter, which can stabilize signals, reduce interference, and ensure stable signal transmission.

The invention has compensation capacitance, compensates and distributes the autotransformer current, impedance matches the inductance of the connecting line between the autotransformers, and ensures the frequency characteristic.

The invention has an isolation resistor, and the resistance value of the isolation resistor is twice the resistance value of the first load resistor and the second load resistor, so that the transmission signals of the two output terminals are independent of each other without being affected, and the stability of transmission is guaranteed.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (5)

1. A high-speed power line carrier communication system signal distribution device, comprising a carrier signal coupler, a first carrier signal modem, a second carrier signal modem, a first communication terminal and a second communication terminal, the first carrier signal modem and the second carrier signal modem A communication terminal is connected, the second carrier signal modem is connected to the second communication terminal, and it is characterized in that it also includes a signal distributor, and the input end of the signal distributor is connected to the carrier signal coupler; The signal distributor includes a first output terminal and a second output terminal, the first output terminal is connected to the first carrier signal modem, and the second output terminal is connected to the second carrier signal modem; The signal distributor also includes: an LC band-pass filter for filtering out 1-40MHz external signals, an impedance matching autotransformer, a distribution autotransformer, an isolation resistor, a first load resistor and a second load resistor, the LC band The pass filter and the distribution autotransformer are respectively connected to the impedance matching autotransformer, the first output terminal and the second output terminal are respectively connected to the distribution autotransformer, and the isolation resistor is connected to the first output terminal and the second output terminal. Between the two output terminals, the first load resistor is connected to the first output terminal, and the second load resistor is connected to the second output terminal. 2. A high-speed power line carrier communication system signal distribution device according to claim 1, wherein the signal distributor also includes a compensation capacitor, and the compensation capacitor is connected to an impedance matching autotransformer or a distribution autotransformer. The lines between are connected. 3. A signal distribution device for a high-speed power line carrier communication system according to claim 1, wherein the LC bandpass filter is composed of an LC filter network inductor and an LC filter network capacitor connected in series. 4. A signal distribution device for a high-speed power line carrier communication system according to claim 1, wherein the resistance value of the first load resistor is equal to the resistance value of the second load resistor. 5. A signal distribution device for a high-speed power line carrier communication system according to claim 4, wherein the resistance of the isolation resistor is twice the resistance of the first load resistor.