Dual-frequency dual-modulation communication method and application in transformer winding deformation tester

Abstract

The invention discloses a dual-frequency dual-modulation communication method and application in a transformer winding deformation tester, and the method comprises the steps: transmitting two pieces of different digital information, namely information A and information B, and transmitting the information A to a direct digital signal generator capable of storing two pieces of different frequency information at the same time; a sine wave signal with a standard amplitude and corresponding to the information A is arranged through an operational amplifier; amplitude amplification is carried out after frequency multiplication, the amplification multiple is related to the information B, and finally a group of mixed air radio frequency signals are formed; performing power amplification on the received signal, and dividing the amplified signal into two paths; one path is subjected to amplitude calibration and power demodulation to obtain transmitted information B, and the other path is subjected to high-pass filtering and frequency demodulation to obtain transmitted information A; when the radio frequency technology is used for space communication, two groups of different information are transmitted at the same time, one-to-many communication requirements can be met, and communication delay and timing sequence disorder of receiving equipment cannot be caused.

Description

Technical Field

[0001] This invention relates to a modulation communication method, and more particularly to a dual-frequency dual-modulation communication method and its application in a transformer winding deformation tester. Background Technology

[0002] Transformers are fundamental equipment for power transmission and distribution, widely used in industry, agriculture, transportation, and urban communities. Under high-frequency voltage, each winding of a transformer can be considered a passive linear two-port network composed of distributed parameters such as linear resistance, inductance (mutual inductance), and capacitance. Its internal characteristics can be described by the transfer function H(jc), such as... Figure 1 As shown, Figure 1 In the diagram, L, K, and C represent the distributed inductance, distributed capacitance, and distributed capacitance to ground per unit length of the winding, respectively. U1 and U2 are the excitation and response voltages of the equivalent network, respectively. US is the voltage of the sinusoidal excitation signal source, Rs is the output impedance of the signal source, and R is the matching resistor.

[0003] If the winding deforms, the distributed inductance, capacitance and other parameters inside the winding will inevitably change, causing the zeros and poles of its equivalent network transfer function H(ja) to change, and thus the frequency response characteristics of the network to change.

[0004] Frequency response analysis can detect transformer winding deformation. In practice, the amplitude-frequency response characteristics of each winding are first measured, and the results are compared longitudinally (over time) or laterally (each winding). Based on the differences in amplitude-frequency response characteristics, potential winding deformation can be determined. The amplitude-frequency response characteristics of the transformer windings are obtained using a frequency scanning method. By continuously changing the frequency of the applied sinusoidal excitation source Us, the ratio of the signal amplitude of the response terminal voltage U2 to the excitation terminal voltage U1 at different frequencies is measured, obtaining the amplitude-frequency response curves of the windings under specified excitation and response terminal conditions.

[0005] Currently, most power systems use frequency response analysis to detect winding deformation. This involves applying a frequency-sweeping sinusoidal signal (1kHz-1MHz) to one end of the transformer winding under test, while simultaneously recording the voltage amplitude and phase angle at that end and the other end. After processing, a set of frequency response curves for the transformer winding is obtained. Comparing the results of two tests allows for the determination of the transformer winding's condition. However, at high frequencies, the transformer impedance can reach several thousand ohms, causing the response voltage U2 to drop to the mV level. Traditional testing methods use cables several meters long to collect the response voltage U2, and the quality of the cable, the testing environment, and the wiring condition significantly affect the signal. Furthermore, in space communication using radio frequency technology, only one set of signals of the same frequency can propagate simultaneously within the working range; otherwise, interference will occur, preventing normal communication. To address this issue, strict control over the space occupancy time of each device is necessary, especially in one-to-many communication, to ensure that different information reaches multiple devices. However, traditional methods can only achieve "pseudo-simultaneity" by increasing bandwidth, not true simultaneous arrival, which still causes timing disorders in the receiving devices. Summary of the Invention

[0006] The purpose of this invention is to solve the aforementioned problems in the background art and to provide a dual-frequency dual-modulation communication method and its application in a transformer winding deformation tester.

[0007] The technical solution of this invention is: a dual-frequency dual-modulation communication method, comprising: S1. Use the transmitting unit to send two different digital information, namely information A and information B. Send information A to a direct digital signal generator that can store two different frequency information at the same time. The signal sent by the direct digital signal generator is processed by an operational amplifier into a sine wave signal with a standard amplitude. The frequency of the processed sine wave signal corresponds to information A. S2. After being multiplied by a frequency multiplier, the signal is sent to a power amplifier for amplitude amplification. The amplification factor is related to information B. When the bit value of information B is "1", the amplification factor of the signal after frequency multiplication of the time series corresponding to that bit is x1. When the bit value of information B is "0", the amplification factor of the signal after frequency multiplication of the time series corresponding to that bit is x0. In this way, a set of mixed air radio frequency signals is finally formed. S3. Utilizing the information received by the receiving unit, the received signal is first amplified, and the amplified signal is then divided into two paths. S4. After amplitude calibration, the idle state during communication is a high-frequency signal, and the start state is a low-frequency signal. By calibrating these two signals, the reference for the amplitude modulation signal can be obtained. Power demodulation is then performed on the calibrated signal to obtain the transmitted information B. Another path undergoes high-pass filtering to remove low-frequency signals, followed by frequency demodulation to obtain the information A transmitted by the high-frequency signal.

[0008] Furthermore, by controlling the state of the frequency selection pin of the direct digital signal generator, different frequency signals are emitted. When the state of the pin is high, a signal with frequency f1 is sent, and when the state of the pin is low, a signal with frequency f2 is sent.

[0009] Furthermore, the transmitting unit includes a direct digital signal generator, an operational amplifier, a frequency multiplier, and a power amplifier, and the receiving unit includes a power amplifier, a high-pass filter, a frequency demodulator, and a power demodulator.

[0010] Furthermore, the mathematical expression for the airborne radio frequency signal is:

[0011] in: f is the amplitude of the signal, which is related to information B; f is the frequency of the signal, which is related to information A.

[0012] Furthermore, x1 is 2-3 times x0.

[0013] The application of the dual-frequency dual-modulation communication method described above in the transformer winding deformation tester employs four data acquisition devices. Three of these devices are connected to one end of transformer windings A, B, and C, respectively, while the other device is connected to the other end of transformer windings A, B, and C. The four data acquisition devices communicate with the control center via dual-frequency dual-modulation communication.

[0014] The beneficial effects of this invention are: when using radio frequency technology for space communication, two different sets of information can be transmitted simultaneously within the working range, and there is no interference between the two sets of signals, so that communication can proceed normally, which can meet the requirements of one-to-many communication and will not cause communication delay or timing disorder of receiving equipment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the basic detection circuit in the frequency response analysis method; Figure 2 This is a block diagram illustrating the working principle of the present invention; Figure 3 This is a communication timing diagram according to an embodiment of the present invention; Figure 4 This is a block diagram illustrating the principle of the wireless winding deformation tester according to an embodiment of the present invention. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the embodiments and accompanying drawings: A dual-frequency dual-modulation communication method, such as Figure 2 As shown, it includes: S1. Two different digital messages, information A and information B, are sent using the transmitting unit. Two different frequency signals are used to represent binary 0 and 1 respectively. Information A (010) and information B (101) are transmitted using a set of signals. Taking 0xaa and 0x55 as examples, the communication adopts serial communication mode, with 1 start bit, 1 stop bit, 8-bit data width, no parity bit, and baud rate of 9600bps. The waveform of its air signal is shown in the figure. Figure 3 As shown; the transmitting unit includes a direct digital signal generator (DDG), a frequency multiplier, an operational amplifier, and a power amplifier. The DDG can simultaneously store two different frequency information. Information A is sent to the DDG. By controlling the state of the frequency selection pin, different frequency signals are emitted. When the state of the pin is high, a signal with frequency f1 is emitted; when the state of the pin is low, a signal with frequency f2 is emitted. The signal emitted by the DDG is processed by the operational amplifier into a sine wave signal with a standard amplitude. The frequency of the processed sine wave signal corresponds to information A. S2. The processed sine wave signal is multiplied by 10 by a frequency multiplier and then sent to a power amplifier for amplitude amplification. The amplification factor is related to information B. When the bit value of information B is "1", the amplification factor of the signal after frequency multiplication corresponding to that bit is x1. When the bit value of information B is "0", the amplification factor of the signal after frequency multiplication corresponding to that bit is x0. This ultimately forms a set of mixed air radio frequency signals, the mathematical expression of which is:

[0017] in: f is the amplitude of the signal, which is related to information B; f is the frequency of the signal, which is related to information A, and x1 is 2-3 times x0; in this example, the maximum power of the signal is 20dB, so 14dB corresponds to a bit value of "0" for information B, and 20dB corresponds to a bit value of "1" for information B. S3. When information is received by the receiving unit, the receiving unit includes a power amplifier, a high-pass filter, a frequency demodulator and a power demodulator. First, the received signal is amplified by power, and the amplified signal is divided into two paths. S4. After amplitude calibration, during communication, the idle state is a high-frequency signal and the start bit is a low-frequency signal. By calibrating these two signals, the reference for the amplitude-modulated signal can be obtained. After the receiving unit completes amplitude calibration, the signal is demodulated to obtain information B. Another path undergoes high-pass filtering to remove low-frequency signals, followed by frequency demodulation to obtain the information A transmitted by the high-frequency signal.

[0018] In this example, the direct digital signal generator is model AD9834, and the power demodulator and frequency demodulator are model AD8310.

[0019] Application of the dual-frequency dual-modulation communication method described above in a transformer winding deformation tester: Collectors A, B, and C are connected to one end of windings A, B, and C, respectively, and collector D is connected to the other end of windings A, B, and C. Collectors A, B, C, and D communicate with the control center using the method of this invention. The control center sends signals that include control signals for the module's switching state. Therefore, when communicating with any module, the amplitude modulation signal contains the status information of the other three modules. During operation, the module has three states: idle state (0), excitation state (1), and measurement state (2). Thus, when communicating with the collectors, the status code of the receiving module can be added to the information in an amplitude modulation manner. The encoding format is shown in the table below.

[0020]

[0021] In practical use, the above encoding method allows the status of each module to be set when sending any command, thereby ensuring the correct working status of all modules and saving space and transmission time.

[0022] The above are merely specific embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual frequency dual modulation communication method, characterized by, The application relates to a method for transmitting two different pieces of information by using a direct digital frequency generator. S1, two different pieces of information, information A and information B, are transmitted by using a transmitting unit; the direct digital frequency generator transmits information A to the direct digital frequency generator which can simultaneously store two different pieces of frequency information; the signal transmitted by the direct digital frequency generator is arranged into a standard-amplitude sine wave signal by using an operational amplifier, and the frequency of the arranged sine wave signal corresponds to information A; S2, the signal is sent into a power amplifier for amplitude amplification after frequency multiplication, and the amplification multiple is related to information B; when the bit value of information B is "1", the amplification multiple of the frequency-multiplied signal corresponding to the time sequence of the bit is x1; when the bit value of information B is "0", the amplification multiple of the frequency-multiplied signal corresponding to the time sequence of the bit is x0; finally, a group of mixed air radio frequency signals are formed; S3, the received information is received by using a receiving unit; first, the received signal is power-amplified, and the amplified signal is divided into two paths; S4, one path is subjected to amplitude calibration; in the communication process, the idle state is a high-frequency signal with a high level, and the start bit is a low-frequency signal with a low level; the two signals are calibrated to obtain the reference of the amplitude modulation signal, and then power demodulation is carried out to obtain the transmitted information B: the other path is subjected to high-pass filtering to filter out the low-frequency signal, and then frequency demodulation is carried out to obtain the information A transmitted by the high-frequency signal.

2. The dual-frequency dual-modulation communication method according to claim 1, characterized in that, Different frequency signals are sent by controlling the state of a frequency selection pin of the direct digital frequency generator; when the state of the pin is a high level, a signal with a frequency f1 is sent; and when the state of the pin is a low level, a signal with a frequency f2 is sent.

3. The dual-frequency dual-modulation communication method of claim 1, wherein, The transmitting unit comprises a direct digital frequency generator, an operational amplifier, a frequency multiplier and a power amplifier; and the receiving unit comprises a power amplifier, a high-pass filter, a frequency demodulator and a power demodulator.

4. The dual-frequency dual-modulation communication method of claim 1, wherein, The mathematical expression of the air radio frequency signal is:

5. Where: is the amplitude of the signal, which is related to the information B; f is the frequency of the signal, which is related to the information A.

6. The dual-frequency dual-modulation communication method of claim 1, wherein, x1 is 2-3 times of x0.

7. The use of the dual-frequency dual-modulation communication method as described above in a transformer winding deformation tester, characterized in that, Four collectors are adopted; three collectors are connected to one end of transformer windings A, B and C respectively, and the other collector is connected to the other end of the transformer windings A, B and C; and the four collectors perform double-frequency and double-modulation communication with a control center.

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