CN107782975A - Distributed grounding resistance detection system and detection method based on radio signal source - Google Patents

Abstract

The invention discloses a distributed grounding resistance detection system and detection method based on a wireless signal source, belonging to the field of electric power transmission. The detection system includes a wireless ground resistance tester and a transformer, wherein: the wireless ground resistance tester includes a power module, a control core module, an excitation signal generation module, an FM transmitter module, a Zigbee module and a communication module; the transformer includes a power module , FM receiver module, synchronization module, voltage transformer module, current transformer module, signal conditioning module, phase measurement module, MCU control module, Zigbee module and self-test module. The invention not only meets the accuracy requirement of measurement, but also solves the problems of cumbersome operations for picking and clamping transformers and long wires being inconvenient to carry during wired measurement.

Description

Distributed grounding resistance detection system and detection method based on wireless signal source

technical field

The invention relates to the field of power transmission, in particular to a distributed grounding resistance detection system and detection method based on a wireless signal source.

Background technique

The prevention of lightning damage is a problem that must be considered when building high-voltage transmission towers. Installing grounding devices in transmission lines is a basic measure to prevent lightning damage. However, since the grounding downconductor is usually exposed to the natural environment, it is easily damaged by force majeure such as wind and rain erosion, resulting in corrosion or fracture of the grounding device. This will greatly reduce the lightning protection effect of the grounding device of the transmission tower, and increase the risk factor of damage to the transmission tower. Therefore, detecting the grounding resistance of transmission towers is a critical step in the maintenance of high-voltage transmission towers.

At present, the methods for measuring the grounding resistance of transmission towers mainly include the three-pole method or the clamp meter method. In comparison, the clamp meter method is more widely used because of its advanced principle. However, whether it is the three-pole method or the clamp meter method, there is currently no dedicated distributed ground resistance detection method based on a wireless signal source, and the mutual inductance voltage needs to be transmitted by wire during measurement.

At present, the more commonly used method is the clamp meter method, which adopts a non-contact measurement method. During the measurement, only the clamp meter is clamped to the down conductor of the transmission tower, and the current source and the voltage source are not arranged separately. ground resistance. When using the clamp meter to measure the grounding resistance, it is necessary to ensure the single-point grounding of the transmission tower, that is, open the other grounding down-conductors of the tower under the premise of retaining one of the down-conductors of the tower, and then clamp the clamp meter on the reserved down-conductor. On-line measurement, repeat the above operations, you can measure the resistance of the four grounding down-conductors of the tower. From the known resistance of the four grounding down-conductors, the grounding resistance of the transmission tower is calculated through the corresponding formula.

The inventor's research has found that at least the following technical problems exist in this prior art: the one is that the distance between the tower pins and the tester is relatively long, and the wire connecting the transformer on the grounding down-lead line and the tester is too long and heavy during measurement. It is not easy to carry; the second is that the wire is too long, which makes it inconvenient to take out the clamping transformer multiple times during the measurement, and the operation of picking up the clamping transformer when measuring multiple transmission towers is cumbersome.

Contents of the invention

The invention provides a distributed grounding resistance detection system and detection method based on a wireless signal source, which not only meets the measurement accuracy requirements, but also solves the problems of cumbersome operations for picking and clamping transformers and long wires that are not easy to carry during wired measurement.

In order to solve the problems of the technologies described above, the present invention provides technical solutions as follows:

On the one hand, the present invention provides a distributed ground resistance detection system based on a wireless signal source, including a wireless ground resistance tester and a transformer, wherein:

The wireless grounding resistance tester comprises a power supply module (1), a control core module (2), an excitation signal generation module (3), an FM transmitter module (4), a Zigbee module (5) and a communication module (6);

The power supply module (1) is responsible for providing suitable voltage for the whole wireless grounding resistance tester, and selects a lithium-ion battery to supply power to each module of the wireless grounding resistance tester after passing through various step-down circuits;

The control core module (2) is composed of a single-chip microcomputer and peripheral function modules, and is responsible for human-computer interaction and information processing. The control core module (2) is responsible for four tasks: one is to control the excitation signal generation module (3) to generate a rated voltage; the other is to receive the mutual inductance current value and phase difference from the Zigbee module (5), and pass Equation 1 calculates the ground resistance impedance value, where Respectively represent the voltage induced by each voltage transformer on the down-conductor, Respectively represent the current generated by the induced voltage on each down-conductor line, when the induced voltage level of the voltage transformer is changed When , the current generated by the induced voltage is R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ respectively represent the resistances of the four down-conductors of the tower, and Z _ge is the impedance value of the grounding resistance; the third is to send a control command to the transformer through the Zigbee module (5); Transmitting the grounding impedance value of the tower and other relevant information about the power transmission tower to the communication module (6);

The excitation signal generation module (3) includes a signal generation module and a power amplification module, which generates a sine wave excitation signal through the control of the control core module (2), and then improves the load driving capability of the circuit through the power amplification module to drive a voltage transformer, and transmit the conditioned AC signal to the FM transmitter module (4);

The frequency modulation transmitter module (4) sends the voltage generated by the excitation signal generation module (3) to the transformer through frequency modulation processing;

The Zigbee module (5) is responsible for receiving the induced current value and the phase difference sent by the Zigbee module (15) of the transformer;

The communication module (6) is a GPRS module, which is responsible for remotely sending the tower position, measurement time, and ground impedance value of the tower to the transmission line tower inspection monitoring system;

The transformer includes a power supply module (7), a frequency modulation receiver module (8), a synchronization module (9), a voltage transformer module (10), a current transformer module (11), a signal conditioning module (12), a phase measurement Module (13), MCU control module (14), Zigbee module (15) and self-inspection module (16);

The power supply module (7) is responsible for providing a suitable voltage for the transformer, and selects a lithium electronic battery to supply power to each module of the transformer after passing through a variety of step-down circuits;

The FM receiver module (8) is responsible for receiving the frequency-modulated voltage sent by the FM transmitter module (4) of the wireless ground resistance tester, and sending it into the synchronization module (9);

The synchronization module (9) is responsible for receiving the control instructions sent by the MCU control module (14), so as to realize the signal synchronization of the four transformers in the entire system, and transmit the synchronized signals to the voltage transformer module (10);

The voltage transformer module (10) and the current transformer module (11) are connected in series to form a pair of transformer jaws, which are clamped on a tower grounding downconductor during measurement, and the voltage and current on the grounding downconductor of the pole tower Take measurements to calculate ground resistance resistance;

The signal conditioning module (12) includes a current-voltage conversion module, a voltage follower, a band-pass filter and an AC-DC conversion circuit. After receiving the induced current transmitted by the current transformer (11), it is converted into a voltage value through the current-voltage conversion module, and then passed through the voltage follower to keep the signal stable, and then passed through the band-pass filter Perform filtering and amplification, and finally convert the AC voltage signal into a DC voltage signal through the AC-DC conversion circuit, and send the signal to the MCU control module (14) for processing;

The phase measurement module (13) is connected to the voltage transformer module (10) and the current transformer module (11), detects the zero-crossing point of the mutual induction voltage and mutual induction current, and sends it to the MCU control module (14) process;

Described MCU control module (14) has three functions: the one, receive the control order that described Zigbee module (15) transmits; The third is to receive the signal transmitted by the signal conditioning module (12) and the phase measurement module (13) to determine the mutual inductance current value and the mutual inductance voltage and current phase difference, and transmit the current value and the phase difference to the Zigbee module ( 15);

The Zigbee module (15) mutual inductance current value and the mutual inductance voltage and current phase difference are sent to the Zigbee module (5) of the wireless ground resistance tester for follow-up calculation; receive the control instruction sent by the wireless ground resistance tester at the same time, Carry out relevant control to the MCU control module (14) of described transformer;

The self-test module (16) controls the opening and closing of the voltage transformer (10) and the current transformer (11) after receiving the signal of the current self-test or voltage self-test of the MCU control module (14) Self-inspection is performed on the voltage transformer (10) and the current transformer (11) to ensure measurement accuracy.

On the other hand, the present invention also provides a detection method of a distributed ground resistance detection system based on a wireless signal source, including:

Step 1: Clamp each pair of voltage transformers and current transformers of the transformer to the grounding down conductor in the same direction as the end of the same name;

Step 2: The wireless ground resistance tester issues instructions to make the excitation signal generation module (3) and the reference voltage signal generation module generate corresponding sinusoidal voltage signals, and the sinusoidal voltage signals are transmitted through the frequency modulation after signal amplification and power amplification Machine module (4) carries out frequency modulation;

Step 3: The FM AC signal is demodulated by the FM receiver module (8) and then transferred to the synchronization module (9) for synchronization;

Step 4: make the MCU control module (14) of the transformer issue a self-check instruction, and the equipment closes the voltage transformer and the current transformer respectively according to the instructions to realize the self-check;

Step 5: The synchronized signal drives the voltage transformer (10), and induces the voltage signal to the grounding down conductor;

Step 6: The current in the grounding down conductor is sensed by the current transformer (11), and is sent to the MCU control module (14) of the sensor after signal conditioning, and the phase measurement module (13) transmits the mutual induction voltage The zero-crossing point detection of electric current is sent to described MCU control module (14);

Step 7: the MCU control module (14) calculates the phase difference of the mutual induction current and the mutual induction voltage and current, and sends the phase difference and current information back to the tower grounding resistance tester via the Zigbee module (15);

Step 8: Inside the tower grounding resistance tester, the control core module (2) performs a series of processing and analysis on the current information and phase information, and solves the equation according to formula 1 to obtain the grounding resistance impedance value;

Step 9: If the calculated self-test results meet the requirements, normal measurement can be performed, and the steps 7 and 8 are repeated by controlling the signal amplitude and frequency on the transformer.

Further, the detection method also includes:

Step 10: The wireless grounding resistance tester sends relevant measurement information to the central monitoring computer through the GPRS module, and stores the data.

The present invention has the following beneficial effects:

The distributed grounding resistance detection system and detection method based on the wireless signal source of the present invention uses the wireless transmission mode to transmit the excitation generated by the signal source to the clamp transformer after signal synchronization using the delay line design of the high-speed digital circuit, and The induced current measured by the transformer is wirelessly transmitted back to the ground resistance tester for calculation. Finally, the relevant information of the measurement is sent to the central monitoring computer through GPRS to complete the measurement of the grounding resistance of a tower. The invention uses a wireless signal source-based wire-free measurement method to measure the grounding resistance, which not only meets the measurement accuracy requirements, but also solves the problems of cumbersome operations for picking and clamping transformers and long wires that are not easy to carry during wired measurement.

Description of drawings

Fig. 1 is the circuit frame diagram of the wireless ground resistance tester of the distributed ground resistance detection system based on wireless signal source of the present invention;

Fig. 2 is the circuit frame diagram of the transformer of the distributed grounding resistance detection system based on wireless signal source of the present invention;

3 is a schematic diagram of a synchronization module of a distributed ground resistance detection system based on a wireless signal source of the present invention;

Fig. 4 is the schematic diagram of the delay module of the distributed grounding resistance detection system based on the wireless signal source of the present invention;

FIG. 5 is a schematic diagram of the FM receiver module of the distributed ground resistance detection system based on the wireless signal source of the present invention.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

On the one hand, the present invention provides a distributed grounding resistance detection system based on a wireless signal source, as shown in Figures 1 to 5, including a wireless grounding resistance tester and a transformer, wherein:

The wireless grounding resistance tester includes a power supply module 1, a control core module 2, an excitation signal generation module 3, an FM transmitter module 4, a Zigbee module 5 and a communication module 6;

The power supply module 1 is responsible for providing suitable voltage for the whole wireless grounding resistance tester. Lithium-ion batteries can be selected to supply power to each module of the wireless grounding resistance tester after passing through various step-down circuits;

The control core module 2 is composed of a single-chip microcomputer and peripheral function modules, and is responsible for human-computer interaction and information processing. The control core module 2 is responsible for four tasks: one is to control the excitation signal generation module 3 to generate the rated voltage; the other is to receive the mutual inductance current value and phase difference from the Zigbee module 5, and calculate the grounding resistance impedance value through formula 1, where Respectively represent the voltage induced by each voltage transformer on the down-conductor, Respectively represent the current generated by the induced voltage on each down-conductor line, when the induced voltage level of the voltage transformer is changed When , the current generated by the induced voltage is R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ represent the resistances of the four down-conductors of the tower respectively, and Z _ge is the impedance value of the grounding resistance; the third is to send the control command to the transformer through the Zigbee module 5; the fourth is the grounding impedance value of the tower and other relevant information of transmission towers are transmitted to the communication module 6;

The excitation signal generation module 3 includes a signal generation module and a power amplification module. The sine wave excitation signal is generated through the control of the control core module 2, and then the load driving capability of the circuit is improved through the power amplification module to drive the voltage transformer, and the conditioned AC The signal is transmitted to the FM transmitter module 4;

The frequency modulation transmitter module 4 sends the voltage generated by the excitation signal generation module 3 to the transformer through frequency modulation processing;

Zigbee module 5 is responsible for receiving the induced current value and the phase difference sent by Zigbee module 15 of transformer;

The communication module 6 may be a GPRS module, which is responsible for remotely sending relevant information such as the position of the tower, the measurement time, and the grounding impedance value of the tower to the power transmission line tower inspection and monitoring system;

The transformer includes a power supply module 7, an FM receiver module 8, a synchronization module 9, a voltage transformer module 10, a current transformer module 11, a signal conditioning module 12, a phase measurement module 13, an MCU control module 14, a Zigbee module 15 and a self-test Module 16;

The power supply module 7 is responsible for providing a suitable voltage for the transformer, and a lithium electronic battery can be selected to supply power to each module of the transformer after passing through various step-down circuits;

The FM receiver module 8 is responsible for receiving the frequency-modulated voltage sent by the FM transmitter module 4 of the wireless ground resistance tester, and sends it into the synchronization module 9;

The synchronization module 9 is responsible for receiving the control command sent by the MCU control module 14, so as to realize the signal synchronization of the four transformers in the whole system, and transmit the synchronized signal to the voltage transformer module 10;

The voltage transformer module 10 and the current transformer module 11 are connected in series to form a pair of transformer jaws, which are clamped on a tower grounding downconductor during measurement, and the voltage and current on the grounding downconductor of the tower are measured to calculate the grounding resistance Resistance;

The signal conditioning module 12 includes a current-voltage conversion module, a voltage follower, a band-pass filter and an AC-DC conversion circuit. After receiving the induced current transmitted by the current transformer 11, it is converted into a voltage value by the current-voltage conversion module, and then the voltage follower is used to maintain the stability of the signal, and then filtered and amplified by the band-pass filter, and finally AC-DC conversion The circuit converts the AC voltage signal into a DC voltage signal, and sends the signal to the MCU control module 14 for processing;

The phase measurement module 13 is connected to the voltage transformer module 10 and the current transformer module 11, detects the zero-crossing point of the mutual induction voltage and the mutual induction current, and sends it to the MCU control module 14 for processing;

The MCU control module 14 has three functions: one is to receive the control command transmitted by the Zigbee module 15; the other is to control the synchronization module 9 and the self-test module 16 to perform signal synchronization and self-test; the third is to receive the signal conditioning module 12 and the phase measurement module 13 The transmitted signal is to determine the mutual induction current value and the mutual induction voltage and current phase difference, and transmit the current value and the phase difference to the Zigbee module 15;

Zigbee module 15 mutual inductance current value and mutual inductance voltage current phase difference send to the Zigbee module 5 of wireless ground resistance tester to carry out follow-up calculation; Receive the control command that wireless ground resistance tester sends over at the same time, carry out correlation to the MCU control module 14 of transformer control;

Self-inspection module 16 carries out self-inspection to voltage transformer 10 and current transformer 11 by controlling the opening and closing of voltage transformer 10 and current transformer 11 after receiving the signal of current self-inspection or voltage self-inspection of MCU control module 14, To ensure measurement accuracy.

The distributed grounding resistance detection system based on the wireless signal source of the present invention uses the wireless transmission method to transmit the excitation generated by the signal source to the clamp transformer after signal synchronization using the delay line design of the high-speed digital circuit, and the transformer The measured induced current is sent back to the ground resistance tester for calculation by wireless means. Finally, the relevant information of the measurement is sent to the central monitoring computer through GPRS to complete the measurement of the grounding resistance of a tower. The invention uses a wireless signal source-based wire-free measurement method to measure the grounding resistance, which not only meets the measurement accuracy requirements, but also solves the problems of cumbersome operations for picking and clamping transformers and long wires that are not easy to carry during wired measurement.

The distributed grounding resistance detection system based on the wireless signal source of the present invention includes a wireless grounding resistance tester and four transformers. The tester is placed in the middle of the bottom of the transmission tower, and the wireless grounding resistance tester and the transformer are transmitted through wireless signals.

Further, the synchronization module 9 is responsible for the synchronization between different transformers. As shown in FIG. 3 , the synchronization module 9 includes a power amplification module 901, a signal selection module 902, a zero-crossing detection module 903 and a delay module 904, wherein:

The power amplification module 901 is responsible for amplifying the amplitude of the signal demodulated by the FM receiver module 8 in two different degrees, and handing it over to the signal selection module 902 to select which amplitude signal to use in the circuit;

The signal selection module 902 is responsible for selecting a signal with a suitable amplitude for the signal channel of the system, so as to measure the amplitude;

The zero-crossing detection module 903 is responsible for detecting the zero-crossing point where the signal changes from negative to positive, and sends a mark t to the control core module 17 after detecting the tenth (can be arbitrarily selected, to reduce the error) zero-crossing point, thereby The control core module 17 can obtain the time difference Δt of the zero-crossing point between the four transformer signals;

Now the control core module 17 can calculate the length to be delayed for the signals of the other three transformer parts to be synchronized, and send it to the delay module 904;

After the delay module 904 has determined the delay length transmitted by the control core module 17, it is responsible for converting the analog signal transmitted by the signal selection module 902 into a digital signal and delaying it through a delay line circuit composed of a FIFO memory, so that four The signal of the transformer is synchronized, and then it is converted into an analog signal and sent to the voltage transformer module 10 for measurement;

In the present invention, the delay module 904 is responsible for delaying the analog signal to a certain degree. As shown in FIG. 4 , the delay module 904 includes an A/D module 9041, a FIFO module 9042, a CPLD module 9043 and a D/A module 9044, wherein:

The A/D module 9041 is responsible for converting the analog signal transmitted by the signal selection module 902 into a digital signal and sending it to the FIFO module 9042 . AD6645 from Analog Devices can be selected. AD6645 is a high-speed, high-performance, single-chip integrated 14-bit A/D conversion chip with a sampling rate of 80MHz or 105MHz;

The FIFO module 9042 is written into the FIFO memory sequentially under the control of the write sequence of the CPLD module 9043 for caching. The large-capacity FIFO chip adopts IDT72V360 of IDT Company. The chip storage capacity is 13l 072×36bit, and the input and output ports can be set to 9 , 18, 36-bit wide, the chip has empty, full, half-full and programmable empty and full flag pins, and can flexibly expand the storage depth and width, up to 166MHz working clock frequency;

When the required delay time arrives, the CPLD module 9043 sends a read timing signal to the FIFO module 9042, so that the output digital signal is sent to the D/A module 9044. The programmable logic device chip (CPLD) adopts the ispMACH4000 series LC4128V75T100 of Lattice Company. The highest working frequency is 400MHz;

The D/A module 9044 is responsible for converting the digital signal output by the FIFO module 9042 into an analog signal to drive the voltage transformer 10. The AD9754 of Analog Devices can be selected, with a conversion rate of 125 MHz and a resolution of 14 bits. AD9754 is internally integrated with a controllable amplifier, which can Output 2 ~ 20mA current, and can be flexibly configured as single-ended or differential output.

Preferably, as shown in Figure 5, the FM receiver module 8 includes a high-frequency signal amplifier 801, a phase-locked loop 802 and a low-pass filter 803, wherein:

The high-frequency signal amplifier 801 is responsible for amplifying the FM signal and sending it into the phase-locked loop 802;

The phase-locked loop 802 performs signal demodulation and output work after receiving the signal amplified by the high-frequency signal amplifier 801;

The phase-locked loop 802 includes a phase detector 8021, a voltage-controlled oscillator 8022 and a follower 8023;

The low-pass filter 803 is responsible for filtering out the high-frequency components from the phase error voltage obtained by the phase detector 8021 after phase detection, so as to obtain a signal that changes with the frequency of the modulation signal;

The phase detector 8021 is responsible for discriminating the signal amplified by the high-frequency signal amplifier 801 and the output of the voltage-controlled oscillator 8022 to obtain a changed phase error voltage, and sending it to the low-pass filter 803;

The voltage-controlled oscillator 8022 receives the signal that is processed by the low-pass filter 803 and changes with the frequency of the modulation signal, and sends the output to the phase detector 8021;

The follower 8023 receives the signal that is processed by the low-pass filter 803 and changes with the frequency of the modulation signal, and obtains the required demodulation signal after processing.

In the present invention, the FM wave is sent to the PLL 802 after being amplified by the high-frequency signal amplifier 801 . In the phase-locked loop 802, the FM wave and the output of the voltage-controlled oscillator 8022 are sent to the phase detector 8021, and the changed phase error voltage is obtained through the phase detector, and the error voltage is filtered by the low-pass filter 803 to remove its high frequency Components, and then obtain a signal that changes with the frequency of the modulating signal, and obtain a demodulated signal through the follower 8023, thereby realizing the demodulation process.

On the other hand, the present invention also provides a detection method of a distributed ground resistance detection system based on a wireless signal source, including:

Step 1: Clamp each pair of voltage transformers and current transformers of the transformer to the grounding down conductor in the same direction as the end of the same name;

Step 2: The wireless grounding resistance tester issues an instruction to make the excitation signal generating module 3 and the reference voltage signal generating module generate corresponding sinusoidal voltage signals, and the sinusoidal voltage signals are frequency-modulated through the FM transmitter module 4 after signal amplification and power amplification;

Step 3: The FM AC signal is demodulated by the FM receiver module 8 and then transferred to the synchronization module 9 for synchronization;

Step 4: Make the MCU control module 14 of the transformer issue a self-check instruction, and the device closes the voltage transformer and the current transformer respectively according to the instructions to realize the self-check;

Step 5: The synchronized signal drives the voltage transformer 10, and induces the voltage signal to the grounding down conductor;

Step 6: The current in the grounding down-conductor is sensed by the current transformer 11, and then transmitted to the MCU control module 14 of the sensor after signal conditioning, and at the same time, the phase measurement module 13 detects the zero-crossing point of the mutual induction voltage and current and transmits it to the MCU control module 14 ;

Step 7: The MCU control module 14 calculates the phase difference of the mutual induction current and the mutual induction voltage and current, and sends the phase difference and current information back to the tower grounding resistance tester via the Zigbee module 15;

Step 8: Inside the tower grounding resistance tester, the control core module 2 performs a series of processing and analysis on the current information and phase information, and solves the equation according to formula 1 to obtain the grounding resistance impedance value;

Step 9: If the calculated self-inspection results meet the requirements, normal measurement can be carried out. Repeat steps 7 and 8 by controlling the signal amplitude and frequency on the transformer.

The detection method of the distributed grounding resistance detection system based on the wireless signal source of the present invention uses the wireless transmission mode to transmit the excitation generated by the signal source to the clamp transformer after signal synchronization using the delay line design of the high-speed digital circuit, and The induced current measured by the transformer is wirelessly transmitted back to the ground resistance tester for calculation. The invention uses a wireless signal source-based wire-free measurement method to measure the grounding resistance, which not only meets the measurement accuracy requirements, but also solves the problems of cumbersome operations for picking and clamping transformers and long wires that are not easy to carry during wired measurement.

Further, detection methods may also include:

Step 10: The wireless grounding resistance tester sends relevant measurement information to the central monitoring computer through the GPRS module, and stores the data.

In the present invention:

(1) The mutual inductance voltage is transmitted by means of frequency modulation, which is the focus of the present invention. The frequency modulation transmitter module of the wireless ground resistance tester sends the voltage generated by the excitation generation module to the transformer part through frequency modulation processing. Since the excitation signal is modulated to a high frequency after modulation, it takes a short time for the modulation signal to pass through the distance between the modulation receivers, and the phase difference generated when the modulation signal arrives at the four transformers is negligible, and the excitation signal can still be regarded as arriving at the same time The transformer section at the four grounding leads of the transmission tower. The FM receiver module of the transformer part is responsible for receiving the FM voltage sent by the FM transmitter module of the wireless ground resistance tester, converting it into a suitable voltage and sending it to the voltage transformer module.

(2) Signal synchronization is the difficult point of how to realize frequency modulation mode transmission. For maintaining signal synchronization between different transformers, the present invention uses a delay line design of a high-speed digital circuit to delay the signal.

The zero-crossing point of the signal from negative to positive is detected by the zero-crossing detection module 903 of the transformer part, and a mark t is sent to the control core module 17 after detecting the tenth zero-crossing point (can be arbitrarily selected to reduce the error) . Thus, the control core module 17 can obtain the time differences Δt ₁ , Δt ₂ , Δt ₃ of the zero-crossing points between the four transformer signals. Therefore, the control core module 17 can calculate the lengths t ₁ , t ₂ , and t ₃ to be delayed for the signals of the other three transformer parts to maintain synchronization, and transmit these three length values to the delay module 904 . After the delay module 904 determines the delay length transmitted by the control core module 17, it converts the analog signal transmitted by the signal selection module 902 into a digital signal and delays it through a delay line circuit composed of a FIFO memory, so that the four mutual inductances The signal of the transformer is synchronized, and then converted into an analog signal and sent to the voltage transformer module 10 for measurement. After using the delay line design, the synchronization of the two signals can be controlled by negative feedback.

(3) The delay line design of the high-speed digital circuit is used to delay the signal. The principle is that the high-frequency analog signal enters the A/D module 9041 and converts it into a digital signal, and is sequentially written into the FIFO module 9042 under the control of the CPLD module 9043 write sequence. For buffering, when the required delay time arrives, the CPLD module 9043 sends a read timing signal to the FIFO module 9042, thereby outputting a digital signal and sending it to the D/A module 9044 to restore the original analog signal. The output analog signal has the same amplitude and frequency except that its phase is different from that of the input analog signal. In this way, the problem of out-of-sync signals after FM can be solved very well.

(4) The AC signal after frequency modulation is demodulated by the frequency modulation receiver to drive the transformer. After the FM signal is amplified by the high-frequency signal amplifier, it is sent to the phase-locked loop. In the phase-locked loop, the output of the FM wave and the voltage-controlled oscillator is sent to the phase detector, and the phase error voltage is obtained through the phase detection. The signal that changes with the frequency of the modulation signal is demodulated by the follower, and the transformer is driven by the demodulated signal.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (6)

1. a kind of distributed grounding resistance detection system based on radio signal source, it is characterised in that including wireless grounding resistance Tester and transformer, wherein：

The wireless earth resistance tester includes power module (1), control core module (2), pumping signal and module occurs (3), frequency modulation transmitter module (4), Zigbee module (5) and communication module (6)；

The power module (1) is responsible for whole wireless earth resistance tester and provides suitable voltage, from lithium ion battery Pass it through each module for power supply to the wireless earth resistance tester after a variety of reduction voltage circuits；

The control core module (2) is made up of single-chip microcomputer and peripheral functional modules, is responsible for man-machine interaction and information processing；Institute State control core module (2) and be responsible for four tasks：First, module (3), which occurs, for the control pumping signal produces rated voltage；Two It is to receive mutual inductance current value and phase difference that the Zigbee module (5) is transmitted, grounding resistance impedance value is calculated by formula 1, Wherein Represent that each voltage transformer senses the voltage on downlead respectively,Table respectively Show due to electric current caused by induced voltage on each downlead, when change voltage transformer induced voltage position When, electric current caused by induced voltage isR₁₁、R₁₂、R₁₃、R₁₄Under representing that four of shaft tower draw respectively The resistance of line, Z_geFor grounding resistance impedance value；Third, control command is sent to the mutual inductance by the Zigbee module (5) Device；Fourth, the relevant information of tower-footing impedance value and other transmission towers is transferred to the communication module (6)；

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Module (3), which occurs, for the pumping signal includes signal generating module and power amplifier module, passes through the control core mould The control of block (2) produces sine wave exciting signal, and the load driving force of circuit is then improved by the power amplifier module So as to driving voltage transformer, and the AC signal after conditioning is transferred to the frequency modulation transmitter module (4)；

The pumping signal voltage caused by module (3) and handles transmission by frequency modulation by the frequency modulation transmitter module (4) occurs To the transformer；

The Zigbee module (5) is responsible for receiving induced electricity flow valuve and phase that the Zigbee module (15) of the transformer is sent Difference；

The communication module (6) is GPRS module, is responsible for long-range transmission shaft tower position, time of measuring, tower-footing impedance value extremely Electric power line pole tower inspection monitoring system；

The transformer includes power module (7), FM receiver module (8), synchronization module (9), voltage transformer module (10), current transformer module (11), Signal-regulated kinase (12), phase measurement module (13), MCU control module (14), Zigbee module (15) and selftest module (16)；

The power module (7) is responsible for the transformer and provides suitable voltage, is passed it through from lithium ion battery a variety of Each module for power supply of the transformer is given after reduction voltage circuit；

The FM receiver module (8) is responsible for receiving frequency modulation transmitter module (4) hair of the wireless earth resistance tester Voltage after the frequency modulation of submitting, it is sent to the synchronization module (9)；

The synchronization module (9) is responsible for receiving the control instruction that the MCU control module (14) sends over, to realize whole system The signal of four transformers is synchronous in system, and the signal after synchronization is transferred into the voltage transformer module (10)；

Voltage transformer module (10) the summation current transformer module (11) series connection, is a pair of transformer jaws, is pressed from both sides during measurement On a shaft tower down conductor, the voltage x current on the down conductor of shaft tower is measured to calculate grounding resistance resistance Value；

The Signal-regulated kinase (12) turns including Current Voltage modular converter, voltage follower, bandpass filter and alternating current-direct current Change circuit；By the Current Voltage modular converter after the induced-current that the current transformer (11) transmits is received Magnitude of voltage is converted to, then keeps the stabilization of signal by the voltage follower, then by bandpass filter progress Filtering and amplification, ac voltage signal is finally converted into d. c. voltage signal by the ac-dc converter circuit, and will letter Number delivering to the MCU control module (14) is handled；

The phase measurement module (13) connects voltage transformer module (10) the summation current transformer module (11), by mutual inductance The zero-crossing examination of voltage and mutual inducing current comes out, and delivers to the MCU control module (14) and handled；

The MCU control module (14) has three functions：First, receive the control life that the Zigbee module (15) transmits Order；Second, the control synchronization module (9) and selftest module (16) carry out signal synchronization and self-test；Adjusted third, receiving the signal Manage module (12) and phase measurement module (13) transmit the signal come to determine mutual inductance current value and mutual voltage current and phase difference, And current value and phase difference are transferred to the Zigbee module (15)；

Zigbee module (15) the mutual inductance current value and mutual voltage current and phase difference are sent to the wireless grounding resistance and surveyed The Zigbee module (5) of examination instrument is subsequently calculated；The control that the wireless earth resistance tester sends over is received simultaneously Instruction, relevant control is carried out to the MCU control module (14) of the transformer；

The selftest module (16) passes through after the signal of electric current self-test or voltage self-test of the MCU control module (14) is received The opening and closing of the voltage transformer (10) summation current transformer (11) is controlled to voltage transformer (10) summation current transformer (11) Self-test is carried out, to ensure measurement accuracy.

2. the distributed grounding resistance detection system according to claim 1 based on radio signal source, it is characterised in that institute Stating synchronization module (9) includes power amplifier module (901), signal selection module (902), zero passage detection module (903) and delay Module (904), wherein：

The power amplifier module (901) is responsible for the signal after the FM receiver module (8) is demodulated and carries out two kinds of differences The amplitude amplification of degree, and transfer to select the signal of which kind of amplitude in the signal selection module (902) selection circuit；

The signal selection module (902) is responsible for the signal of the signalling channel selection suitable amplitude of system, to carry out amplitude Measurement；

The zero passage detection module (903) is responsible for coming out signal by the positive zero-crossing examination of negative change, and is detecting the tenth A mark t is sent to control core module (17) after zero crossing, thus control core module (17) can obtain four transformer letters The time difference Δ t of zero crossing between number；

Now the control core module (17) can calculate the signal length to be delayed that keep synchronous the other three transformer Degree, and it is sent to the Postponement module (904)；

The Postponement module (904) is responsible for after the delay length sent by the control core module (17) is determined Analog signalses that the signal selection module (902) transmits are switched into data signal by being made up of FIFO memory Delay line is postponed so that the signal of four transformers is synchronous, then is translated into analog signal and is sent to the electricity Pressure transformer module (10) measures.

3. the distributed grounding resistance detection system according to claim 2 based on radio signal source, it is characterised in that institute Stating Postponement module (904) includes A/D modules (9041), fifo module (9042), CPLD modules (9043) and D/A modules (9044), wherein：

It is data signal that the A/D modules (9041), which are responsible for the analog-signal transitions of the signal selection module (902) transmission, And it is sent into the fifo module (9042)；

The fifo module (9042) writes FIFO memory under the control that the CPLD modules (9043) write sequential and entered successively Row caching；

The CPLD modules (9043) send when reaching required time delay and read clock signal to the fifo module (9042), so as to which output digit signals deliver to the D/A modules (9044)；

The digital signal transition that the D/A modules (9044) are responsible for exporting the fifo module (9042) is analog signal to drive Move the voltage transformer (10).

4. the distributed grounding resistance detection system according to claim 1 based on radio signal source, it is characterised in that institute Stating FM receiver module (8) includes high-frequency signal amplifier (801), phaselocked loop (802) and low pass filter (803), wherein：

The high-frequency signal amplifier (801) is responsible for amplifying FM signal, and is sent into the phaselocked loop (802)；

The phaselocked loop (802) carries out signal demodulation after the signal after receiving the high-frequency signal amplifier (801) amplification Output services；

The phaselocked loop (802) includes phase discriminator (8021), voltage controlled oscillator (8022) and follower (8023)；

The low pass filter (803) is responsible for the phase error voltage obtained after the phase discriminator (8021) phase demodulation filtering height Frequency composition, so as to obtain the signal for changing and changing with frequency modulating signal；

The phase discriminator (8021) is responsible for the signal after the high-frequency signal amplifier (801) is amplified and the voltage controlled oscillator (8022) output phase demodulation obtains the phase error voltage of change, and is sent to the low pass filter (803)；

The voltage controlled oscillator (8022) receive after the low pass filter (803) processing with frequency modulating signal change and The signal of change, and output is sent into the phase discriminator (8021)；

The follower (8023) receives changing with frequency modulating signal after the low pass filter (803) processing and changed Signal, required demodulated signal is obtained after processing.

A kind of 5. detection method of the distributed grounding resistance detection system based on radio signal source, it is characterised in that including：

Step 1：Each pair of voltage transformer summation current transformer of transformer is clipped in ground connection by the consistent mode of extreme direction of the same name On downlead；

Step 2：The wireless earth resistance tester, which sends instruction, makes the pumping signal that module (3) and reference voltage letter occur Number module occurs produces corresponding sine voltage signal, and sine voltage signal is after signal amplification and power amplification by described Frequency modulation transmitter module (4) carries out frequency modulation；

Step 3：Frequency modulation AC signal is passed to the synchronization module (9) after being demodulated by the FM receiver module (8) and carried out together Step；

Step 4：The MCU control module (14) of the transformer is made to send self-checking command, equipment is closed respectively according to instruction is different Voltage transformer summation current transformer is so as to realizing self-test；

Step 5：Signal after synchronization drives the voltage transformer (10), and this voltage signal is sensed to down conductor；

Step 6：By the electric current in the current transformer (11) inductive grounding downlead, the biography is passed to after signal condition The MCU control module (14) of sensor, while the phase measurement module (13) comes out the zero-crossing examination of mutual voltage electric current Pass to the MCU control module (14)；

Step 7：The MCU control module (14) calculates the phase difference of mutual inducing current and mutual voltage electric current, and by phase Difference and current information are passed back in pole tower ground resistance tester via the Zigbee module (15)；

Step 8：Inside pole tower ground resistance tester, the control core module (2) is by the current information and phase information A series of Treatment Analysis are carried out, solving equation according to formula 1 draws grounding resistance impedance value；

Step 9：If the result of the self-test after calculating meets the requirements, you can is normally measured, by controlling on the transformer Signal amplitude and frequency, repeating said steps 7 and step 8.

6. the detection method of the distributed grounding resistance detection system according to claim 5 based on radio signal source, its It is characterised by, the detection method also includes：

Step 10：The wireless earth resistance tester, which sends correlation measurement information to center monitoring by GPRS module, to be calculated Machine, and by data storage.