A high-precision insulation resistance detection circuit

Abstract

The present invention relates to a high-precision insulation resistance detection circuit, comprising an insulation detection module and a voltage divider module connected in series; the insulation detection module comprises a plurality of insulation resistance detection units connected in parallel; the insulation resistance detection unit comprises a battery, a detection circuit and a diode connected in series; the detection circuit comprises a first insulation resistor, a second insulation resistor, an inductor and a button switch, the first insulation resistor and the second insulation resistor form a series circuit, the inductor and the button switch are connected in parallel with the series circuit; the voltage divider module comprises a voltage divider circuit and a grounding circuit, the voltage divider circuit comprises a first switch, a first voltage divider resistor, a second voltage divider resistor and a third voltage divider resistor connected in series in sequence. The application of the present invention solves the problems of inaccurate resistance detection, false alarms, large detection errors and complex calculations in the insulation resistance detection circuit in the prior art.

Description

Technical Field

[0001] The invention relates to the field of insulation monitoring devices, and in particular to a high-precision insulation resistance detection circuit. Background Art

[0002] The DC system of power plants and substations provides working power for control and signal systems, relay protection and automatic devices, etc., which is crucial to ensure the continuous and safe operation of power plants and power stations. This requires that the DC system and its power supply network should have higher reliability and continuous power supply capacity. As one of the measures to improve the continuous power supply capacity, the DC system operates in a "floating ground" mode, which means that the normal operation of the system is not affected when a ground fault occurs once. However, if a second ground fault occurs while this potential hazard exists, it may endanger the continuous operation of the system. The insulation level needs to be continuously monitored. When the insulation level drops to a certain level, an alarm signal is issued and the insulation weak link is located. The DC system insulation monitoring device is set up to achieve this goal.

[0003] The insulation monitoring device monitors the insulation level of the DC system by detecting the insulation resistance of the system. The main methods include the bridge method, the low-frequency signal injection method and the leakage current detection method.

[0004] However, there are many problems with the current insulation resistance detection circuit, such as: complex detection circuit, inaccurate insulation resistance value detection, false alarm, large error in detection result, complex calculation formula and excessive occupation of processor resources.

[0005] In addition, the existing insulation resistance detection circuit cannot determine whether its own detection circuit is working properly, which can easily lead to false alarms. These problems will affect the reliability of the insulation monitoring device. If the potential hazards cannot be resolved, it will bury huge hidden dangers for subsequent work.

[0006] Therefore, it is urgent to propose a new technical solution to solve the above problems. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a high-precision insulation resistance detection circuit for an insulation monitoring device. The specific technical solution is as follows:

[0008] A high-precision insulation resistance detection circuit comprises an insulation detection module and a voltage dividing module connected in series;

[0009] Further, the insulation detection module includes a plurality of groups of insulation resistance detection units connected in parallel;

[0010] Further, the insulation resistance detection unit comprises a battery, a detection circuit and a diode connected in series;

[0011] Further, the detection circuit includes a first insulation resistor, a second insulation resistor, an inductor device and a button switch, the first insulation resistor and the second insulation resistor form a series circuit, and the inductor device and the button switch are connected in parallel with the series circuit;

[0012] Furthermore, the voltage divider module includes a voltage divider circuit and a grounding circuit, the voltage divider circuit includes a first switch, a first voltage divider resistor, a second voltage divider resistor and a third voltage divider resistor connected in series in sequence; the grounding circuit is connected between the first voltage divider resistor and the second voltage divider resistor.

[0013] Furthermore, the insulation detection module is connected in series with one end of the first switch.

[0014] Furthermore, one end of the third voltage-dividing resistor is connected in series with the negative electrode of the battery.

[0015] Furthermore, the grounding circuit includes a second switch.

[0016] Furthermore, the detection circuit is grounded.

[0017] Furthermore, a connection point between the first insulation resistor and the second insulation resistor is connected to the ground.

[0018] Furthermore, the voltage-dividing circuit also includes a voltmeter, and the voltmeter is connected in parallel with the third voltage-dividing resistor.

[0019] The present invention has the following beneficial effects:

[0020] 1. The insulation resistance detection circuit of the present invention has a simple circuit, a higher precision in calculating the insulation resistance value, and a small amount of processor calculation, thus occupying less processor resources;

[0021] 2. The insulation resistance detection circuit of the present invention can perform circuit self-test and judge the circuit to detect whether the circuit is working normally;

[0022] 3. The detection circuit described in the present invention has a simpler calculation method than the prior art, reduces the error rate, and ensures the accuracy of the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A circuit diagram of the detection circuit of the present invention;

[0025] Figure 2 It is an equivalent circuit diagram of the detection circuit of the present invention.

[0026] Among them: 1-battery, 2-diode, 3-first insulation resistor, 4-second insulation resistor, 5-inductor, 6-button switch, 7-first switch, 8-first voltage-dividing resistor, 9-second voltage-dividing resistor, 10-third voltage-dividing resistor, 11-second switch, 12-voltmeter. DETAILED DESCRIPTION

[0027] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0028] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, fixed connection, detachable connection, or integrated; mechanical connection, or electrical connection; direct connection, or indirect connection through an intermediate medium, or internal connection between two elements or interaction between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Example

[0031] The existing insulation resistance detection circuit has problems such as complex detection circuit, inaccurate insulation resistance value detection, false alarm, large error in detection result, complex calculation formula and excessive processor resource occupation. Therefore, the present invention provides a high-precision insulation resistance detection circuit to solve the above problems.

[0032] Figure 1 A circuit diagram of the detection circuit of the present invention; Figure 2 It is an equivalent circuit diagram of the detection circuit of the present invention.

[0033] Please refer to Figure 1-2 , the present invention provides a high-precision insulation resistance detection circuit, comprising an insulation detection module and a voltage divider module connected in series;

[0034] The insulation detection module comprises a plurality of groups of insulation resistance detection units connected in parallel;

[0035] The insulation resistance detection unit comprises a battery 1 (U1), a detection circuit and a diode 2 (D1) connected in series;

[0036] The detection circuit includes a first insulation resistor 3 (Rp1), a second insulation resistor 4 (Rn1), an inductor 5 (L1) and a button switch 6 (Q1), wherein the first insulation resistor 3 (Rp1) and the second insulation resistor 4 (Rn1) form a series circuit, and the inductor 5 (L1) and the button switch 6 (Q1) are connected in parallel with the series circuit;

[0037] The voltage divider module includes a voltage divider circuit and a grounding circuit. The voltage divider circuit includes a first switch 7 (S0), a first voltage divider resistor 8 (Rs), a second voltage divider resistor 9 (Ra) and a third voltage divider resistor 10 (Rb) connected in series in sequence; the grounding circuit is connected between the first voltage divider resistor 8 (Rs) and the second voltage divider resistor 9 (Ra).

[0038] Furthermore, the insulation detection module is connected in series with one end of the first switch 7 (S0).

[0039] Furthermore, one end of the third voltage-dividing resistor 10 (Rb) is connected in series with the negative electrode of the battery 1 (U1).

[0040] Furthermore, the grounding circuit includes a second switch 11 (S1).

[0041] Furthermore, the detection circuit is grounded.

[0042] Furthermore, a connection point between the first insulation resistor 3 ( Rp1 ) and the second insulation resistor 4 ( Rn1 ) is connected to the ground.

[0043] Furthermore, the voltage-dividing circuit further includes a voltmeter 12 (V0), and the voltmeter 12 (V0) is connected in parallel with the third voltage-dividing resistor 10 (Rb).

[0044] The insulation resistance detection circuit of the present invention has a detection method in a working state as follows:

[0045] 1. Connect the circuit. In the initial state, open the first switch 7 (S0) and close the second switch 11 (S1). The processor samples the voltage of the third voltage-dividing resistor 10 (Rb) as V1.

[0046] 2. Disconnect the first switch 7 (S0), disconnect the second switch 11 (S1), wait for a period of time, and the processor samples the voltage V2 of the third voltage-dividing resistor 10 (Rb);

[0047] 3. Calculate whether the value of V2-V1 is within the threshold value, thereby determining whether the second switch 11 (S1) is closed or open;

[0048] 4. Close the first switch 7 (S0), open the second switch 11 (S1), and the processor samples the voltage V3 of the third voltage-dividing resistor 10 (Rb) at this time;

[0049] 5. Turn off the first switch 7 (S0), turn off the second switch 11 (S1), and the processor samples the voltage V4 of the resistor Rb at this time;

[0050] 6. Calculate whether the value of V4-V3 is within the threshold value, and determine whether the first switch 7 (S0) is closed or open;

[0051] 7. Through the front-stage inductor device 5 (L1-Lm) and the button switch 6 (Q1-Qm), the voltage is boosted to the set voltage value Ubus to keep Ubus stable;

[0052] 8. Close the first switch 7 (S0), close the second switch 11 (S1), measure the voltage V1_1 of the sampling resistor third voltage divider resistor 10 (Rb) at this time, and use the superposition principle to list the equation of V1_1, insulation resistance and PV voltage as equation 1;

[0053] 9. Open the first switch 7 (S0), close the second switch 11 (S1), measure the voltage V1_0 of the sampling resistor third voltage divider resistor 10 (Rb) at this time, apply Kirchhoff's principle, list the equation of V1_0, insulation resistance and PV voltage, and set it as equation 2;

[0054] 10. Combine equation 1 and equation 2 to calculate the insulation resistance.

[0055] Build as Figure 1 , 2 In the circuit shown, the button switch 6 (Q1-Qm) and the diode 2 (D1-Dm) can be used as inverter power circuit components, and the first switch 7 (S0) and the second switch 11 (S1) are recyclable or equivalent mechanical switch components.

[0056] The insulation resistance detection circuit of the present invention has a simple circuit and a concise calculation method, and the precision and accuracy of the insulation resistance value calculated by the corresponding circuit are also improved;

[0057] The detection circuit of the present invention can perform circuit self-test, such as detecting the open and closed states of the first switch 7 (S0) and the second switch 11 (S1) in the above detection method, so as to judge whether the circuit is working normally.

[0058] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0059] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify and vary the above embodiments within the scope of the present invention.

Claims

1. A high-precision insulation resistance detection circuit, characterized in that: It includes an insulation detection module and a voltage dividing module connected in series; The insulation detection module comprises a plurality of groups of insulation resistance detection units connected in parallel; The insulation resistance detection unit comprises a battery (1), a detection circuit and a diode (2) connected in series; The detection circuit comprises a first insulation resistor (3), a second insulation resistor (4), an inductor (5) and a button switch (6), wherein the first insulation resistor (3) and the second insulation resistor (4) form a series circuit, and the inductor (5) and the button switch (6) are connected in parallel with the series circuit; The voltage dividing module comprises a voltage dividing circuit and a grounding circuit, wherein the voltage dividing circuit comprises a first switch (7), a first voltage dividing resistor (8), a second voltage dividing resistor (9) and a third voltage dividing resistor (10) which are connected in series in sequence; the grounding circuit is connected between the first voltage dividing resistor (8) and the second voltage dividing resistor (9), and the grounding circuit comprises a second switch (11); The voltage dividing circuit also includes a voltmeter (12), and the voltmeter (12) is connected in parallel with the third voltage dividing resistor (10).

2. The detection circuit according to claim 1, characterized in that: The insulation detection module is connected in series with one end of the first switch (7).

3. The detection circuit according to claim 1, characterized in that: One end of the third voltage-dividing resistor (10) is connected in series with the negative electrode of the battery (1).

4. The detection circuit according to claim 1, characterized in that: The detection circuit is grounded.

5. The detection circuit according to claim 1 or 4, characterized in that: The connection point between the first insulation resistor (3) and the second insulation resistor (4) is connected to the ground.

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