A transient grounding signal extraction circuit

Abstract

The present invention discloses a transient grounding signal extraction circuit, comprising: a voltage detection circuit and a current detection circuit; a line to be detected is respectively connected to the input ends of the current detection circuit and the voltage detection circuit; the output ends of the voltage detection circuit and the current detection circuit are respectively connected to a calculation chip; the voltage detection circuit and the current detection circuit respectively convert the voltage signal and the current signal extracted from the line to be detected into a fluctuation signal for output; the calculation chip is used to determine a fault according to the fluctuation signal. The circuit provided by the present invention not only has a low investment cost, but also has a high hardware implementation performance, and realizes the extraction of an abnormal grounding signal by displaying the waveform on a display device or analyzing the fluctuation signal by a single-chip microcomputer.

Description

Technical Field

[0001] The present invention relates to the field of overhead line grounding fault detection, and specifically to a circuit for extracting transient grounding signals. Background Art

[0002] Detecting grounding faults in overhead lines is a difficult problem in power distribution line fault location. As a common means of detecting grounding faults in overhead lines, the grounding fault detection function of fault indicators is also a technical problem that needs to be solved. Currently, the commonly used grounding indicators in the power distribution network include: active indicators and passive indicators. Among them, active indicators require installing a signal source device in the substation, injecting a specific current signal into the power grid from the secondary side of the PT, and then detecting this characteristic signal through a signal detector to determine the fault line. Passive indicators mostly use current mutation to judge grounding, and the line with the largest 5th harmonic zero-sequence current in the line is judged as the fault line. At the same time, this type of indicator can overcome the compensation effect of the arc suppression coil.

[0003] Although judging grounding faults through active indicators is relatively stable, it has a high cost and is difficult to install and maintain. For some lines with large load fluctuations, it increases the difficulty of detecting characteristic signals; however, when judging grounding faults through passive indicators, the hardware requirements for extracting the 5th harmonic are very high. At the same time, since the 5th harmonic component of the fault current is small (less than 10% of the fault current), the accuracy of fault location is low. Summary of the Invention

[0004] In order to solve the above deficiencies in the prior art, the present invention provides a circuit for extracting transient grounding signals for passive indicators.

[0005] The technical solution provided by the present invention is: a circuit for extracting transient grounding signals, including: a voltage detection circuit and a current detection circuit;

[0006] The line to be detected is respectively connected to the input ends of the current detection circuit and the voltage detection circuit;

[0007] The output ends of the voltage detection circuit and the current detection circuit are respectively connected to a calculation chip;

[0008] The voltage detection circuit and the current detection circuit respectively convert the voltage signal and the current signal extracted from the line to be detected into a fluctuation signal and output it;

[0009] The calculation chip is used to determine a fault according to the fluctuation signal.

[0010] Preferably, the voltage detection circuit includes: a filtering circuit, a voltage trigger circuit, and a driving circuit connected in sequence.

[0011] Preferably, the current detection circuit includes: resistor R26, a filtering circuit, a current trigger circuit, capacitor C33, capacitor C34, and a driving circuit;

[0012] The resistor R26, the filtering circuit, and the current trigger circuit are connected in parallel in sequence, and the capacitor C33 and the capacitor C34 are connected in parallel;

[0013] The current trigger circuit is connected to the driving circuit through the capacitor C33 and the capacitor C34 respectively.

[0014] Preferably, the filtering circuit includes:

[0015] Three capacitors and three resistors;

[0016] The first capacitor, the second capacitor, and the third capacitor are connected in series and then connected in parallel with the first resistor;

[0017] The input signal is connected to the connection point of the first capacitor and the first resistor;

[0018] One end of the second resistor is connected to the connection point of the first capacitor and the second capacitor, and the other end of the second resistor is grounded;

[0019] One end of the third resistor is connected to the connection point of the second capacitor and the third capacitor, and the other end of the third resistor is grounded;

[0020] When the input signal is a current, in the voltage filtering circuit, the resistor R26 is connected at the connection point of the input signal and the first capacitor and the first resistor, and the other end of the resistor R26 is grounded.

[0021] Preferably, the voltage trigger circuit includes:

[0022] Resistor R81, capacitor C104, a high-level trigger circuit, and a low-level trigger circuit;

[0023] The output end of the filtering circuit is connected to the resistor R81, and the other end of the resistor R81 is respectively connected to the capacitor 104, the high-level trigger circuit, and the low-level trigger circuit; the other end of the capacitor C104 is grounded;

[0024] The high-level trigger circuit is configured to output a rising pulse when there is a voltage fluctuation in the line to be detected and the fluctuation reaches the high-level trigger limit value;

[0025] The low-level trigger circuit is configured to output a falling pulse when there is a voltage fluctuation in the line to be detected and the fluctuation reaches the low-level trigger limit value.

[0026] Preferably, the high-level trigger circuit includes:

[0027] Resistor R142, resistor R150, capacitor C133 and capacitor C140;

[0028] Capacitor C133 is connected in series with resistor R142 and then connected to the drive circuit;

[0029] One end of resistor R150 is connected between capacitor C133 and resistor R142, one end of capacitor C140 is connected between resistor R142 and the drive circuit, and the other ends of resistor R150 and capacitor C140 are connected to the power supply.

[0030] Preferably, the low-level trigger circuit includes:

[0031] Resistor R143, resistor R151, capacitor C134 and capacitor C130;

[0032] Capacitor C134 is connected in series with resistor R143 and then connected to the drive circuit;

[0033] One end of resistor R151 is connected between capacitor C134 and resistor R143, one end of capacitor C130 is connected between resistor R143 and the drive circuit, and the other ends of resistor R151 and capacitor C130 are grounded.

[0034] Preferably, the current trigger circuit includes:

[0035] Zener diode Q1, resistor R4, resistor R6, resistor R5, resistor R7, resistor R8, resistor R27, resistor R9, capacitor C6, capacitor C7, capacitor C8, capacitor C9, capacitor C10 and capacitor C17;

[0036] Capacitor C6 and resistor R6 are in series, capacitor C7 and resistor R7 are in series, capacitor C9 and resistor R8 are in series, capacitor C10 and resistor R9 are in series, and capacitor C17 and resistor R27 are in series;

[0037] The output end of the filter circuit, the zener diode Q1, and the other end of capacitor C6 are connected to resistor R4, and the other end of resistor R4, the other end of capacitor C7, and the other end of capacitor C9 are connected to resistor R5;

[0038] The other end of resistor R5, the other end of capacitor C10 and the other end of resistor R27 are connected;

[0039] One end of capacitor C8 is connected to the connection point between capacitor C6 and resistor R6, and the other end of capacitor C8 is connected to the connection point between capacitor C7 and resistor R7;

[0040] One end of capacitor C11 is connected to the connection point between capacitor C9 and resistor R8, and the other end of capacitor 11 is connected to the connection point between capacitor C10 and resistor R9;

[0041] The other ends of the voltage stabilizing diode Q1, resistor R6, resistor R7, resistor R8, resistor R9 and capacitor C17 are grounded;

[0042] The connection point between the capacitor C17 and the resistor R27 serves as the output terminal of the current detection trigger circuit.

[0043] Preferably, the value range of the capacitor C104 or the capacitor C17 is 47 pF to 1 uF.

[0044] Preferably, the drive circuit includes:

[0045] A high-level drive circuit and a low-level drive circuit;

[0046] The input end of the high-level drive circuit is connected to the output end of the high-level trigger circuit, and is used to output a high level when the high-level drive circuit receives a rising pulse sent by the high-level trigger circuit;

[0047] The input end of the low-level drive circuit is connected to the output end of the low-level trigger circuit, and is used to output a low level when the low-level drive circuit receives a falling pulse sent by the low-level trigger circuit;

[0048] The output ends of the high-level drive circuit and the low-level drive circuit are connected to the calculation chip.

[0049] Preferably, the high-level drive circuit includes:

[0050] Transistor T15, resistor R146, resistor R152, resistor R154 and capacitor C141;

[0051] The output end of the high-level trigger circuit is connected to the base of the transistor T15. The emitter of the transistor T15 is connected to the power supply, and the collector of the transistor T15 is grounded after being connected in series with the capacitor C141;

[0052] The resistor R152, resistor R154 and resistor R146 are connected in series in sequence. The other end of the resistor R152 is connected to the power supply. The connection point between the resistor R152 and the resistor R154 is connected to the base of the transistor T15, and the other end of the resistor R146 is grounded;

[0053] The connection point between the resistor R154 and the resistor R146 and the collector of the transistor T15 are connected in series and used as the output end of the high-level drive circuit.

[0054] Preferably, the low-level drive circuit includes:

[0055] Transistor T14, resistor R147, resistor R153, resistor R155 and capacitor C142;

[0056] The output terminal of the low-level trigger circuit is connected to the base of the triode T14. The emitter of the triode T14 is grounded, and the collector of the triode T14 is connected to the power supply after being serially connected with a capacitor C142;

[0057] The resistors R147, R155, and R153 are serially connected in sequence. The other end of the resistor R147 is connected to the power supply. The connection point between the resistor R155 and the resistor R153 is connected to the base of the triode T14, and the other end of the resistor R153 is grounded;

[0058] The connection point between the resistor R147 and the resistor R155 and the collector of the triode T14 are serially connected as the output terminal of the low-level drive circuit.

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] For the technical solution provided by the present invention, the extraction circuit includes a voltage detection circuit and a current detection circuit; the line to be detected is respectively connected to the input terminals of the current detection circuit and the voltage detection circuit; the output terminals of the voltage detection circuit and the current detection circuit are respectively connected to a calculation chip; the voltage detection circuit and the current detection circuit respectively convert the voltage signal and the current signal extracted from the line to be detected into a fluctuation signal for output; the calculation chip is used to determine a fault according to the fluctuation signal. The circuit provided by the present invention not only has a low finished product input, but also has a high hardware implementation. By analyzing the waveform output by the calculation chip or the fluctuation signal, the abnormal grounding signal extracted by the voltage detection circuit and the current detection circuit can be analyzed.

[0061] For the technical solution provided by the present invention, by adjusting the mutation threshold values of the current and voltage signal circuits, that is, by adjusting the values of the capacitor C104 or the capacitor C17, a full-hardware grounding judgment can be realized, and it can also be used as a threshold circuit to cooperate with the calculation chip for software intelligent judgment to conduct a detailed analysis of the grounding judgment and locate the fault.

[0062] For the technical solution provided by the present invention, by capturing the transient change characteristics of the line current and the induced electric field for judgment, and combining with the software refinement of the calculation chip for grounding fault detection, the cost and the limitation of signal input brought by the active indicator are reduced, and the situation of single grounding criterion of the traditional passive indicator is compensated. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 is the voltage detection circuit diagram of the present invention;

[0064] Figure 2-1 is the schematic diagram of the front-end circuit of the current detection circuit of the present invention;

[0065] Figure 2-2 Schematic diagram of the current trigger circuit of the current detection circuit of the present invention;

[0066] Figure 2-3 Schematic diagram of the backend circuit of the current detection circuit of the present invention;

[0067] Figure 3 Voltage detection circuit diagram with component values in the embodiment of the present invention;

[0068] Figure 4-1 Resistor R26 and filter circuit diagram of the current detection circuit with component values in the embodiment of the present invention;

[0069] Figure 4-2 Current trigger circuit diagram with component values in the embodiment of the present invention;

[0070] Figure 4-3 Driver circuit diagram of the current detection circuit with component values in the embodiment of the present invention;

[0071] Figure 5 Schematic diagram of connecting the output ends of the voltage detection circuit and the current detection circuit to the single-chip microcomputer in the embodiment of the present invention;

[0072] Figure 6 Simulation waveform diagram of the output of the voltage detection circuit in the embodiment of the present invention;

[0073] Figure 7 Schematic diagram of the extraction circuit of the transient grounding signal in the embodiment of the present invention. Detailed implementation manners

[0074] To better understand the present invention, the content of the present invention will be further described below with reference to the accompanying drawings of the specification and examples.

[0075] As Figure 7 shown, an extraction circuit of a transient grounding signal provided by the present invention includes a voltage detection circuit and a current detection circuit;

[0076] The line to be detected is respectively connected to the input ends of the current detection circuit and the voltage detection circuit;

[0077] The output ends of the voltage detection circuit and the current detection circuit are respectively connected to the computing chip;

[0078] The voltage detection circuit and the current detection circuit respectively convert the voltage signal and the current signal extracted from the line to be detected into a fluctuating signal and output it;

[0079] The computing chip is used to determine a fault according to the fluctuating signal.

[0080] Among them, the voltage detection circuit is as Figure 1As shown in the figure, a voltage signal is obtained from the line to be detected through a voltage transformer or resistor voltage reduction. The voltage signal passes through a filter circuit composed of capacitor C101 (470 pF), resistor R101 (47 MΩ), capacitor C103 (470), resistor R102 (3.9 kΩ), and resistor R103 (3.9 kΩ) to smooth the sine wave and filter and buffer the voltage signal in the detection line. Resistor R81 (150 kΩ) and capacitor C104 (470 pF) further stabilize and filter the voltage. Capacitors C133 (1 nF) and C134 (1 nF) filter out the DC part of the line and only allow the mutant voltage to pass through.

[0081] Capacitors C133, resistor R150, resistor R142, and capacitor C140 form the T15 trigger circuit. Since resistor R150 is pulled up to 3 V, when there is no voltage fluctuation in the line, the base of T15 is pulled high and the output of T15 is low. Once there is a voltage fluctuation in the line and it reaches the trigger limit, T15 will conduct and output a high level. The greater the line fluctuation, the longer the high-level output time.

[0082] Capacitors C134, resistor R151, resistor R143, and capacitor C139 form the T14 trigger circuit. Since resistor R151 is pulled down to 0 V, when there is no voltage fluctuation in the line, the base of T14 is pulled low and the output of T14 is high. Once there is a voltage fluctuation in the line and it reaches the trigger limit, T14 will conduct and output a low level. The greater the line fluctuation, the longer the low-level output time.

[0083] The third part of the circuit is the drive part, which is implemented by a pair of triodes. When there is a fluctuation in the line, one of T14 and T15 outputs a high level and the other outputs a low level to drive the display part to display the fault information or send it to the single-chip microcomputer for processing.

[0084] As Figure 2-1 、 Figure 2-2 and Figure 2-3 shown, the current detection circuit can be divided into three parts. The front-end circuit and the back-end circuit of the voltage detection circuit and the current detection circuit are the same.

[0085] As Figure 2-2 shown, the current trigger circuit includes:

[0086] Zener diode Q1, resistor R4, resistor R6, resistor R5, resistor R7, resistor R8, resistor R27, resistor R9, capacitor C6, capacitor C7, capacitor C8, capacitor C9, capacitor C10, and capacitor C17;

[0087] Capacitor C6 is in series with resistor R6, capacitor C7 is in series with resistor R7, capacitor C9 is in series with resistor R8, capacitor C10 is in series with resistor R9, and capacitor C17 is in series with resistor R27;

[0088] The output terminal of the filtering circuit, the other end of the voltage stabilizing diode Q1, and the other end of the capacitor C6 are connected to the resistor R4, and the other end of the resistor R4, the other end of the capacitor C7, and the other end of the capacitor C9 are connected to the resistor R5;

[0089] The other end of the resistor R5, the other end of the capacitor C10, and the other end of the resistor R27 are connected;

[0090] One end of the capacitor C8 is connected to the connection point between the capacitor C6 and the resistor R6, and the other end of the capacitor C8 is connected to the connection point between the capacitor C7 and the resistor R7;

[0091] One end of the capacitor C11 is connected to the connection point between the capacitor C9 and the resistor R8, and the other end of the capacitor 11 is connected to the connection point between the capacitor C10 and the resistor R9;

[0092] The other ends of the voltage stabilizing diode Q1, the resistor R6, the resistor R7, the resistor R8, the resistor R9, and the capacitor C17 are grounded;

[0093] The connection point between the capacitor C17 and the resistor R27 serves as the output terminal of the current detection trigger circuit.

[0094] This embodiment also provides Figure 3 , Figure 4-1 , Figure 4-2 and Figure 4-3 , which includes the values of the components. Taking the voltage detection circuit as an example, the signal input terminal forms a filtering circuit through the capacitor C101 (470 pF), the resistor R101 (47 M), the capacitor C103 (470), the resistor R102 (3.9 k), and the resistor R103 (3.9 K) to smooth the sine wave and filter and buffer the voltage signal in the detection line. The resistor R81 (150 k) and the capacitor C104 (470 p) further stabilize and filter, and the capacitors C133 (1 nF) and C134 (1 nF) filter out the DC part of the line and only allow the mutated voltage to pass.

[0095] The second part is the voltage trigger circuit, including: the resistor R81, the capacitor C104, the high-level trigger circuit, and the low-level trigger circuit;

[0096] The output terminal of the filtering circuit is connected to the resistor R81, and the other end of the resistor R81 is respectively connected to the capacitor 104, the high-level trigger circuit, and the low-level trigger circuit; the other end of the capacitor C104 is grounded;

[0097] The high-level trigger circuit is used to output a rising pulse when there is a voltage fluctuation in the line to be detected and the fluctuation reaches the high-level trigger limit value;

[0098] The low-level trigger circuit is used to output a falling pulse when there is a voltage fluctuation in the line to be detected and the fluctuation reaches the low-level trigger limit value.

[0099] C133, R150, R142, and C140 form the T15 trigger circuit. Since R150 is pulled up to 3V, when there is no voltage fluctuation in the line, the base of T15 is pulled high, and the output of T15 is low. Once there is a voltage fluctuation in the line and it reaches the trigger limit, T15 will conduct and output a high level. The greater the line fluctuation, the longer the high-level output time.

[0100] C134, R151, R143, and C139 form the T14 trigger circuit. Since R151 is pulled down to 0V, when there is no voltage fluctuation in the line, the base of T14 is pulled low, and the output of T14 is high. Once there is a voltage fluctuation in the line and it reaches the trigger limit, T14 will conduct and output a low level. The greater the line fluctuation, the longer the low-level output time.

[0101] Among them, the high-level trigger circuit includes:

[0102] Resistor R142, resistor R150, capacitor C133, and capacitor C140;

[0103] Capacitor C133 is connected in series with resistor R142 and then connected to the drive circuit;

[0104] One end of resistor R150 is connected between capacitor C133 and resistor R142, one end of capacitor C140 is connected between resistor R142 and the drive circuit, and the other ends of resistor R150 and capacitor C140 are connected to the power supply.

[0105] Furthermore, the low-level trigger circuit includes:

[0106] Resistor R143, resistor R151, capacitor C134, and capacitor C130;

[0107] Capacitor C134 is connected in series with resistor R143 and then connected to the drive circuit;

[0108] One end of resistor R151 is connected between capacitor C134 and resistor R143, one end of capacitor C130 is connected between resistor R143 and the drive circuit, and the other ends of resistor R151 and capacitor C130 are grounded.

[0109] Furthermore, the high-level trigger circuit includes:

[0110] Resistor R142, resistor R150, capacitor C133, and capacitor C140;

[0111] The capacitor C133 is connected in series with the resistor R142 and then connected to the drive circuit;

[0112] One end of the resistor R150 is connected between the capacitor C133 and the resistor R142, one end of the capacitor C140 is connected between the resistor R142 and the drive circuit, and the other ends of the resistor R150 and the capacitor C140 are connected to the power supply.

[0113] The third part of the circuit is the drive part, which is implemented by a pair of triodes. When there is a fluctuation in the line, T14 and T15 output a high level and a low level respectively to drive the display part to display fault information or send it to the single-chip microcomputer for processing.

[0114] The drive part includes: a high-level drive circuit and a low-level drive circuit;

[0115] The input end of the high-level drive circuit is connected to the output end of the high-level trigger circuit, and is used to output a high level when the high-level drive circuit receives the rising pulse sent by the high-level trigger circuit;

[0116] The input end of the low-level drive circuit is connected to the output end of the low-level trigger circuit, and is used to output a low level when the low-level drive circuit receives the falling pulse sent by the low-level trigger circuit;

[0117] The output ends of the high-level drive circuit and the low-level drive circuit are connected to the computing chip.

[0118] Among them, the high-level drive circuit includes:

[0119] The triode T15, the resistors R146, R152, R154, and the capacitor C141;

[0120] The output end of the high-level trigger circuit is connected to the base of the triode T15, the emitter of the triode T15 is connected to the power supply, and the collector of the triode T15 is grounded after being connected in series with the capacitor C141;

[0121] The resistors R152, R154, and R146 are connected in series in sequence. The other end of the resistor R152 is connected to the power supply. The connection point between the resistor R152 and the resistor R154 is connected to the base of the triode T15, and the other end of the resistor R146 is grounded;

[0122] The connection point between the resistor R154 and the resistor R146 and the collector of the triode T15 are connected in series and used as the output end of the high-level drive circuit.

[0123] Further, the low-level drive circuit includes:

[0124] Triode T14, resistor R147, resistor R153, resistor R155 and capacitor C142;

[0125] The output terminal of the low-level trigger circuit is connected to the base of the triode T14. The emitter of the triode T14 is grounded, and the collector of the triode T14 is connected to the power supply after being connected in series with the capacitor C142;

[0126] The resistors R147, R155 and R153 are connected in series in sequence. The other end of the resistor R147 is connected to the power supply. The connection point between the resistor R155 and the resistor R153 is connected to the base of the triode T14, and the other end of the resistor R153 is grounded;

[0127] The connection point between the resistor R147 and the resistor R155 and the collector of the triode T14 are connected in series and used as the output terminal of the low-level drive circuit.

[0128] The current detection part is also divided into three parts. The difference from the voltage detection part is that a resistor R26 is added before the filter circuit, a capacitor is added in the drive circuit part, and the trigger circuit is completely different. Specifically, it includes: the current signal is obtained through a current transformer, and then the current front-end resistor R26 converts the current signal of the current transformer into a voltage signal. R1, R2, R3, R4, C1, C2, C3, C4 are used for front-end filtering. The Q1 voltage regulator limits the maximum value of the regulated voltage signal. The middle part of the circuit is two consecutive filter circuits. After two-stage filtering in the middle, it is ensured that there are no spike peak interferences affecting the judgment in the current output, and the output reaches R27 and C17. After the adjustment and matching of R27 and C17, a stable sine wave within the trigger range is generated.

[0129] Compared with the voltage part circuit, the signals input to the triodes T4 and T5 do not have the pull-up and pull-down processing. This is because Q1 limits the signal so that it will not exceed the uncontrollable range.

[0130] After passing through C33 and C34 to filter out the DC part and pass the fluctuations in the line, the drive triodes T5 and T4 are turned on to output the fault fluctuation waveform.

[0131] The single-chip microcomputer in the present invention only needs to have an interrupt function. In this embodiment, MPS430F6749A is taken as an example. As Figure 5As shown in the figure, connect the output points U+ of T14 and T15 for voltage part detection to the IO pin P7.1 of MPS430F6749A, and connect the output point U- to the IO pin P7.2 of MPS430F6749A. Connect the output points I+ and I- of T4 and T5 for current part detection to the IO pins P7.4 and P7.5 of MPS430F6749A. The Port7 of MPS430F6749A can detect the rising and falling of the input level to generate an interrupt. According to the interrupt combination caused by the change of the pin level, the change ratio of the current and voltage in the circuit can be judged, so as to make a judgment on the generation of the grounding signal.

[0132] According to Figure 6 the simulation waveform, when the signal level detected by the P7.1 pin connected to the T14 triode becomes low, it can be judged that the voltage signal has a large enough change. At the same time, it should not cause the change of the P7.2 pin connected to the T15 triode. When the change amplitude increases, it will cause the level change of the P7.2 pin, from low level to high level spike. At the same time, the quantitative calculation of the voltage change amplitude can be judged according to the length of the level change time.

[0133] (1) The components and parts necessary to form the product. Among them, C104 in the voltage detection circuit and C17 in the current detection circuit can adjust and set the threshold value of the detection line signal change. The value range of C104 and C17 is 47pF to 1uF.

[0134] (2) Conduct circuit simulation verification on the output signal of the drive circuit. Taking the voltage detection loop as an example, the simulation waveform is as Figure 6 shown. When the input voltage changes, the triode T14 conducts and outputs a pulse; when the input signal has a positive mutation and meets the threshold value, the triode T15 conducts and outputs a pulse. Combining the output signals of T14 and T15 can identify the transient change of the input signal. At the same time, a grounding judgment is given in combination with the change of the current signal.

[0135] The above are only the embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention pending approval.

Claims

1. An extraction circuit for transient grounding signals, characterized in that, Comprising: A voltage detection circuit and a current detection circuit; The line to be detected is respectively connected to the input ends of the current detection circuit and the voltage detection circuit; The output ends of the voltage detection circuit and the current detection circuit are respectively connected to a calculation chip; The voltage detection circuit and the current detection circuit respectively convert the voltage signal and the current signal extracted from the line to be detected into a fluctuation signal for output, and the calculation chip is used to determine a fault according to the fluctuation signal; The voltage detection circuit includes: a filtering circuit, a voltage trigger circuit and a driving circuit connected in sequence; The voltage trigger circuit includes: a resistor R81, a capacitor C104, a high-level trigger circuit and a low-level trigger circuit; the output end of the filtering circuit is connected to the resistor R81, and the other end of the resistor R81 is respectively connected to the capacitor C104, the high-level trigger circuit and the low-level trigger circuit; the other end of the capacitor C104 is grounded; the high-level trigger circuit is used to output a rising pulse when there is a voltage fluctuation in the line to be detected and the fluctuation reaches the high-level trigger limit value; the low-level trigger circuit is used to output a falling pulse when there is a voltage fluctuation in the line to be detected and the fluctuation reaches the low-level trigger limit value; The high-level trigger circuit includes: a resistor R142, a resistor R150, a capacitor C133 and a capacitor C140; the capacitor C133 is connected in series with the resistor R142 and then connected to the driving circuit; one end of the resistor R150 is connected between the capacitor C133 and the resistor R142, one end of the capacitor C140 is connected between the resistor R142 and the driving circuit, and the other ends of the resistor R150 and the capacitor C140 are connected to the power supply; The low-level trigger circuit includes: a resistor R143, a resistor R151, a capacitor C134 and a capacitor C130; the capacitor C134 is connected in series with the resistor R143 and then connected to the driving circuit; one end of the resistor R151 is connected between the capacitor C134 and the resistor R143, one end of the capacitor C130 is connected between the resistor R143 and the driving circuit, and the other ends of the resistor R151 and the capacitor C130 are grounded; The current detection circuit includes: a resistor R26, a filtering circuit and a current trigger circuit connected in parallel in sequence, and capacitors C33 and C34 connected in parallel, and the current trigger circuit is respectively connected to the driving circuit through the capacitors C33 and C34; The current trigger circuit includes: a voltage stabilizing diode Q1, resistors R4, R6, R5, R7, R8, R27, R9, capacitors C6, C7, C8, C9, C10 and C17; The capacitor C6 is connected in series with the resistor R6, the capacitor C7 is connected in series with the resistor R7, the capacitor C9 is connected in series with the resistor R8, the capacitor C10 is connected in series with the resistor R9, and the capacitor C17 is connected in series with the resistor R27; The output end of the filtering circuit, the voltage stabilizing diode Q1, and the other end of the capacitor C6 are connected to the resistor R4, and the other end of the resistor R4, the other end of the capacitor C7, and the other end of the capacitor C9 are connected to the resistor R5; The other end of the resistor R5, the other end of the capacitor C10 are connected to the other end of the resistor R27; One end of the capacitor C8 is connected to the connection point between the capacitor C6 and the resistor R6, and the other end of the capacitor C8 is connected to the connection point between the capacitor C7 and the resistor R7; One end of the capacitor C11 is connected to the connection point between the capacitor C9 and the resistor R8, and the other end of the capacitor C11 is connected to the connection point between the capacitor C10 and the resistor R9; The other ends of the voltage regulator diode Q1, the resistor R6, the resistor R7, the resistor R8, the resistor R9 and the capacitor C17 are grounded; The connection point between the capacitor C17 and the resistor R27 is used as the output terminal of the current detection trigger circuit; By adjusting the mutation threshold values of the current and voltage signal circuits, that is, by adjusting the values of the capacitor C104 or the capacitor C17, a full-hardware ground judgment is realized.

2. The circuit according to claim 1, wherein The filtering circuit includes: Three capacitors and three resistors; The first capacitor, the second capacitor and the third capacitor are connected in series and then connected in parallel with the first resistor; The input signal is connected to the connection point of the first capacitor and the first resistor; One end of the second resistor is connected to the connection point of the first capacitor and the second capacitor, and the other end of the second resistor is grounded; One end of the third resistor is connected to the connection point of the second capacitor and the third capacitor, and the other end of the third resistor is grounded; When the input signal is a current, in the voltage filtering circuit, a resistor R26 is connected to the connection point of the input signal, the first capacitor and the first resistor, and the other end of the resistor R26 is grounded.

3. The circuit according to claim 1, wherein The value range of the capacitor C104 or the capacitor C17 is 47 pF to 1 μF.

4. The circuit according to claim 1, characterized in that, The driving circuit includes: A high-level driving circuit and a low-level driving circuit; The input end of the high-level driving circuit is connected to the output end of the high-level trigger circuit, and is used to output a high level when the high-level driving circuit receives a rising pulse sent by the high-level trigger circuit; The input end of the low-level driving circuit is connected to the output end of the low-level trigger circuit, and is used to output a low level when the low-level driving circuit receives a falling pulse sent by the low-level trigger circuit; The output ends of the high-level driving circuit and the low-level driving circuit are connected to the calculation chip.

5. The circuit according to claim 4, characterized in that, The high-level driving circuit includes: A triode T15, a resistor R146, a resistor R152, a resistor R154 and a capacitor C141; The output end of the high-level trigger circuit is connected to the base of the triode T15, the emitter of the triode T15 is connected to the power supply, and the collector of the triode T15 is grounded after being connected in series with the capacitor C141; The resistor R152, the resistor R154 and the resistor R146 are connected in series in turn. The other end of the resistor R152 is connected to the power supply. The connection point between the resistor R152 and the resistor R154 is connected to the base of the triode T15, and the other end of the resistor R146 is grounded; The connection point between the resistor R154 and the resistor R146 and the collector of the triode T15 are connected in series and used as the output end of the high-level driving circuit.

6. The circuit according to claim 4, wherein The low-level driving circuit includes: A triode T14, a resistor R147, a resistor R153, a resistor R155 and a capacitor C142; It is connected to the base of the triode T14 at the output end of the low-level trigger circuit. The emitter of the triode T14 is grounded, and the collector of the triode T14 is connected to the power supply after being connected in series with the capacitor C142; The resistor R147, the resistor R155, and the resistor R153 are connected in series in sequence. The other end of the resistor R147 is connected to the power supply. The connection point between the resistor R155 and the resistor R153 is connected to the base of the triode T14, and the other end of the resistor R153 is grounded; The connection point between the resistor R147 and the resistor R155 and the collector of the triode T14 are connected in series and used as the output end of the low-level drive circuit.

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