Self-adaptive electric field sensing system based on fast harmonic decomposition

Abstract

The invention relates to a self-adaptive electric field sensing system based on fast harmonic decomposition, and belongs to the technical field of power sensors. Comprising a voltage sensor, an automatic gain equalization circuit, a multipath harmonic decomposition circuit and a digital-analog collector, one end of the automatic gain equalization circuit is connected with the center of an electric field sensor through a twisted-pair line, and the other end of the automatic gain equalization circuit is connected with the multipath harmonic decomposition circuit; the multi-path harmonic decomposition circuit is connected with a digital-analog collector; the automatic gain equalization circuit can equalize the amplitude of a wide-screen electric field signal acquired by the voltage sensor; the multi-path harmonic decomposition circuit comprises n harmonic decomposition circuits and a channel selector; and the channel selector can selectively connect any harmonic decomposition circuit in the n harmonic decomposition circuits and is connected with the digital-analog acquisition system to display the decomposition result of the connected harmonic decomposition circuit on the output value of the automatic gain equalization circuit.

Description

Technical Field

[0001] The present invention relates to an adaptive electric field sensing system based on fast harmonic decomposition, belonging to the technical field of power sensors. Background Art

[0002] The secondary substation system is an important part of a substation. Abnormalities in the secondary system, such as broken grounding copper bars and cable leakage faults, are highly concealed and difficult to detect through conventional daily inspections and other methods. Although power outages for maintenance can detect some insulation faults, the cost of power outages is high, and new faults caused by the maintenance itself have also been frequently reported. The electric field intensity signal is a key characteristic quantity for monitoring the health status of in-station power equipment. Introducing an electric field measurement signal for early warning of secondary system faults is a feasible technical route.

[0003] Based on research on power equipment faults, it is found that when judging early faults such as external insulation, the specific absolute value of the electric field is not the most critical characteristic, but the ratio of each harmonic to the total amplitude (or total power) is the key to judging the equipment status. Therefore, ensuring a constant output amplitude of the signal and effectively decomposing each harmonic can achieve fast fault diagnosis based on the electric field signal. However, when substation operation and maintenance personnel approach power equipment with similar devices in hand, it is found that the output signal of the conditioning circuit changes from small to large, with a span range of up to a hundred times. This inevitably causes the conditioning circuit to work at two extremes: difficult amplification of weak signals and output saturation of strong signals. At the same time, the signal output from the conditioning circuit to the subsequent system is a broadband signal. If a specific harmonic needs to be concerned, it is necessary to perform sliding window FFT processing in software, which requires a large processing delay and is extremely likely to cause the loss of key characteristics. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: how to ensure the fast and effective decomposition of each harmonic of the electric field signal on the premise of a constant output amplitude of the electric field signal.

[0005] To solve the above technical problem, the technical solution proposed by the present invention is: an adaptive electric field sensing system based on fast harmonic decomposition, including a voltage sensor, an automatic gain equalization circuit, a multi-channel harmonic decomposition circuit, and an analog-to-digital collector. One end of the automatic gain equalization circuit is connected to the center of the electric field sensor through a twisted pair line, and the other end is connected to the multi-channel harmonic decomposition circuit; the multi-channel harmonic decomposition circuit is connected to an analog-to-digital collector; The automatic gain equalization circuit can equalize the amplitude of the broadband electric field signal collected by the voltage sensor; The multi-channel harmonic decomposition circuit includes n harmonic decomposition circuits and a channel selector; the harmonic decomposition circuit includes a first decomposition resistor, a second decomposition resistor, a first decomposition capacitor, a second decomposition capacitor, and a harmonic decomposition differential amplifier; One end of the first decomposition resistor is connected to the output end of the automatic gain equalization circuit, and the other end is respectively connected to the first decomposition capacitor and the second decomposition capacitor; the first decomposition capacitor is connected to the output end of the harmonic decomposition differential amplifier; the second decomposition capacitor is connected to the inverting input end of the harmonic decomposition differential amplifier; a second decomposition resistor is connected between the first decomposition capacitor and the second decomposition capacitor; the non-inverting input end of the harmonic decomposition differential amplifier is grounded, and the output end of the harmonic decomposition differential amplifier is connected to the channel selector; The circuit connection conditions of the n harmonic decomposition circuits are the same and are all connected to the channel selector. The only difference is that the resistance values of the selected first decomposition resistor and second decomposition resistor are different, and the capacitance values of the selected first decomposition capacitor and second decomposition capacitor are different; The channel selector can select any one of the n harmonic decomposition circuits to be connected and display the decomposition result of the output value of the automatic gain equalization circuit by the connected harmonic decomposition circuit to the analog-to-digital acquisition system.

[0006] Further, the automatic gain equalization circuit includes a first differential amplifier, a second differential amplifier, and a third differential amplifier; a first resistor is connected to the non-inverting input end of the first differential amplifier; a second resistor is connected to the inverting input end of the first differential amplifier; both the first resistor and the second resistor are connected with wires and extend to form a twisted pair wire connected to the center of the voltage sensor; a third resistor is connected between the non-inverting input end and the inverting input end of the first differential amplifier; a fourth resistor is connected between the output end and the non-inverting input end of the first differential amplifier; a fifth resistor is connected to the output end of the first differential amplifier; the fifth resistor is connected to the non-inverting input end of the second differential amplifier; a sixth resistor is connected to the inverting input end of the second differential amplifier, and the sixth resistor is grounded; a seventh resistor is connected between the output end and the inverting input end of the second differential amplifier; a rectifier diode is connected to the output end of the second differential amplifier; the rectifier diode is connected with an eighth resistor; the eighth resistor is connected to the inverting input end of the third differential amplifier; a regulated power supply is connected to the non-inverting input end of the third differential amplifier, and an integrating capacitor is connected between the output end and the inverting input end of the third differential amplifier; a ninth resistor is connected to the output end of the third differential amplifier, and the ninth resistor is connected to the inverting input end of the first differential amplifier.

[0007] Further, the voltage sensor includes an upper plate, a lower plate, and an equipotential ring; the radius of the upper plate is smaller than the radius of the lower plate; the upper plate and the equipotential ring are in the same plane and parallel to the plane where the lower plate is located; there is no electrical connection between the upper plate and the equipotential ring; the upper plate, the lower plate, and the equipotential ring are electrically insulated.

[0008] Advantages of the present invention: The present invention provides an adaptive electric field intensity sensing system with characteristics of rapid measurement and anti-interference. By setting up an automatic gain control loop, the problem of difficult sensing caused by a large fluctuation range of signal amplitude is solved. At the same time, by setting up multiple harmonic decomposition channels, the rapidity and continuity of electric field signal sensing are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic circuit diagram of other parts of the adaptive electric field sensing in the present invention.

[0010] Figure 2 It is a schematic structural diagram of the voltage sensor in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] The following further describes an adaptive electric field sensing system based on rapid harmonic decomposition of the present invention in conjunction with the drawings and specific embodiments. Embodiment

[0012] The adaptive electric field sensing system in this embodiment, as shown in Figure 1 and 2 , includes a voltage sensor, an automatic gain equalization circuit, a multiple harmonic decomposition circuit, and a digital-to-analog collector. One end of the automatic gain equalization circuit is connected to the center of the electric field sensor through a twisted pair line, and the other end is connected to the multiple harmonic decomposition circuit; the multiple harmonic decomposition circuit is connected to the digital-to-analog collector. The automatic gain equalization circuit can equalize the amplitude of the wide-screen electric field signal collected by the voltage sensor.

[0013] The voltage sensor includes an upper plate, a lower plate, and an equipotential ring; the radius of the upper plate is smaller than that of the lower plate; the upper plate and the equipotential ring are in the same plane and parallel to the plane where the lower plate is located; there is no electrical connection between the upper plate and the equipotential ring; the upper plate, the lower plate, and the equipotential ring are electrically insulated from each other.

[0014] The automatic gain equalization circuit includes a first differential amplifier U1, a second differential amplifier U2, and a third differential amplifier U3; the positive input terminal of the first differential amplifier U1 is connected to a first resistor R in1 ; the negative input terminal of the first differential amplifier is connected to a second resistor R in2 ; both the first resistor R in1 and the second resistor R in2 are connected with wires and extend to form a twisted pair to be connected to the center of the voltage sensor; a third resistor R g is connected between the positive input terminal and the negative input terminal of the first differential amplifier U1; a fourth resistor R fb is connected between the output terminal and the positive input terminal of the first differential amplifier U1; the output terminal of the first differential amplifier U1 is connected to a fifth resistor Ra ; The fifth resistor R a The reverse input terminal of the second differential amplifier U2 is connected to the sixth resistor R b , the sixth resistor R b A seventh resistor R is connected between the output terminal and the reverse input terminal of the second differential amplifier U2 f The output end of the second differential amplifier U2 is connected to a rectifier diode D it ; Rectifier diode D it Connected with the eighth resistor R it ; The eighth resistor R it The positive input terminal of the third differential amplifier U3 is connected to a regulated power supply, and an integrating capacitor C is connected between the output terminal and the reverse input terminal of the third differential amplifier U3. it The output end of the third differential amplifier U3 is connected to a ninth resistor V G , the ninth resistor V G Connected to the inverting input terminal of the first differential amplifier U1.

[0015] The multi-channel harmonic decomposition circuit includes n harmonic decomposition circuits and a channel selector; the harmonic decomposition circuit includes a first decomposition resistor R 1-1 , the second decomposition resistor R 1-2 , the first decomposition capacitor C 1-1 , the second decomposition capacitor C 1-2 and harmonic decomposition differential amplifier U 1-1 ; The first decomposition resistor R 1-1 One end is connected to the output end of the automatic gain equalization circuit, and the other end is connected to the first decomposition capacitor C 1-1 and the second decomposition capacitor C 1-2 Connection: First decomposition capacitor C 1-1 With harmonic decomposition differential amplifier U 1-1 The output end is connected; the second decomposition capacitor C 1-2 With harmonic decomposition differential amplifier U 1-1 The reverse input terminal is connected; the first decomposition capacitor C 1-1 and the second decomposition capacitor C 1-2 A second decomposition resistor R is connected between 1-2 ; Harmonic decomposition differential amplifier U 1-1 The non-inverting input terminal of the harmonic decomposition differential amplifier U is grounded. 1-1 The output end is connected to the channel selector; The circuit connections of the n harmonic decomposition circuits are all the same and are all connected to the channel selector, and the only difference is that the resistance values of the selected first decomposition resistor and the second decomposition resistor are different, and the capacitance values of the selected first decomposition capacitor and the second decomposition capacitor are different; The channel selector can select any one of the n harmonic decomposition circuits to be connected and connect it to the digital-to-analog acquisition system to display the decomposition result of the output value of the automatic gain equalization circuit by the connected harmonic decomposition circuit.

Claims

1. An adaptive electric field sensing system based on fast harmonic decomposition, characterized in that: It includes a voltage sensor, an automatic gain equalization circuit, a multi-channel harmonic decomposition circuit, and an analog-to-digital collector. One end of the automatic gain equalization circuit is connected to the center of the electric field sensor through a twisted pair line, and the other end is connected to the multi-channel harmonic decomposition circuit; the multi-channel harmonic decomposition circuit is connected to an analog-to-digital collector; The automatic gain equalization circuit can equalize the amplitude of the wide-screen electric field signal collected by the voltage sensor; The multi-channel harmonic decomposition circuit includes n harmonic decomposition circuits and a channel selector; The harmonic decomposition circuit includes a first decomposition resistor, a second decomposition resistor, a first decomposition capacitor, a second decomposition capacitor, and a harmonic decomposition differential amplifier; One end of the first decomposition resistor is connected to the output end of the automatic gain equalization circuit, and the other end is respectively connected to the first decomposition capacitor and the second decomposition capacitor; the first decomposition capacitor is connected to the output end of the harmonic decomposition differential amplifier; the second decomposition capacitor is connected to the inverting input end of the harmonic decomposition differential amplifier; A second decomposition resistor is connected between the first decomposition capacitor and the second decomposition capacitor; The non-inverting input end of the harmonic decomposition differential amplifier is grounded, and the output end of the harmonic decomposition differential amplifier is connected to the channel selector; The circuit connection conditions of the n harmonic decomposition circuits are the same and are all connected to the channel selector. The only difference is that the resistance values of the selected first decomposition resistor and second decomposition resistor are different, and the capacitance values of the selected first decomposition capacitor and second decomposition capacitor are different; The channel selector can select and connect any one of the n harmonic decomposition circuits and is connected to the analog-to-digital acquisition system to display the decomposition result of the connected harmonic decomposition circuit on the output value of the automatic gain equalization circuit.

2. The adaptive electric field sensing system according to claim 1, wherein: The automatic gain equalization circuit includes a first differential amplifier, a second differential amplifier, and a third differential amplifier; a first resistor is connected to the non-inverting input end of the first differential amplifier; a second resistor is connected to the inverting input end of the first differential amplifier; both the first resistor and the second resistor are connected with wires and extend to form a twisted pair to be connected to the center of the voltage sensor; a third resistor is connected between the non-inverting input end and the inverting input end of the first differential amplifier; a fourth resistor is connected between the output end and the non-inverting input end of the first differential amplifier; a fifth resistor is connected to the output end of the first differential amplifier; the fifth resistor is connected to the non-inverting input end of the second differential amplifier; a sixth resistor is connected to the inverting input end of the second differential amplifier, and the sixth resistor is grounded; a seventh resistor is connected between the output end and the inverting input end of the second differential amplifier; a rectifier diode is connected to the output end of the second differential amplifier; the rectifier diode is connected to an eighth resistor; the eighth resistor is connected to the inverting input end of the third differential amplifier; a regulated power supply is connected to the non-inverting input end of the third differential amplifier, and an integrating capacitor is connected between the output end and the inverting input end of the third differential amplifier; a ninth resistor is connected to the output end of the third differential amplifier, and the ninth resistor is connected to the inverting input end of the first differential amplifier.

3. The adaptive electric field sensing system according to claim 1, characterized in that: The voltage sensor includes an upper plate, a lower plate, and an equipotential ring; the radius of the upper plate is smaller than the radius of the lower plate; the upper plate and the equipotential ring are in the same plane and parallel to the plane where the lower plate is located; there is no electrical connection between the upper plate and the equipotential ring; the upper plate, the lower plate, and the equipotential ring are electrically insulated from each other.

Images