Direct current system insulation detection method and portable insulation detection and verification integrated device

Abstract

The invention discloses a DC system insulation detection method and a portable insulation detection and verification integrated device, and the method comprises the steps: constructing a DC system bus insulation detection circuit, and building a mathematical model of bus voltage and bus insulation resistance; detection switches K4 and K12 are arranged in the bus insulation detection circuit; a balance bridge switch K5, a balance bridge switch K13, a balance bridge switch K6 and a balance bridge switch K14; the K4, the K12, the K5, the K13 and the K6 are switched on, the K14 is switched off, and the voltage to ground of the positive bus and the voltage to ground of the negative bus are measured; after each measurement, the to-be-identified parameters are updated by reusing a recursive least square method through regularized data; remaining switch states are kept unchanged, the K6 is switched off, the K14 is switched on, and voltages to ground of the positive bus and the negative bus are measured; after each measurement, the to-be-identified parameters are updated by reusing a recursive least square method through regularized data; and positive and negative bus insulation resistance values are calculated by combining the to-be-identified parameters with the mathematical model, so that the accuracy of bus insulation resistance measurement is improved.

Description

Technical Field

[0001] The invention relates to the technical field of power system insulation detection, and in particular to a DC system insulation detection method and a portable insulation detection and verification integrated device. Background Art

[0002] In modern power systems, DC power supply systems are increasingly used, especially in the fields of renewable energy, rail transit and energy storage systems. As an important part of power transmission, the insulation performance of the positive and negative busbars of the DC system directly affects the safety and reliability of the system. With the increase of voltage levels and equipment integration, the calculation and monitoring of insulation resistance has become particularly important.

[0003] At present, busbar insulation detection mainly relies on a structure composed of a balanced bridge and an unbalanced bridge. The balanced bridge is used to clamp the positive and negative busbar voltages to ground and control the fluctuation range of the busbar voltage to ground during the unbalanced bridge switching process. The main function of the unbalanced bridge is to form busbar voltage fluctuations by switching bridge arms, and to perform circuit analysis on the voltage fluctuations to calculate the DC busbar insulation resistance to ground. For example:

[0004] 1) Reference 1 "Liu Bingjie. Research on DC bus grounding insulation detection method [J]. Electric Power and Energy, 2018, 39(02): 209-211." First, the insulation detection circuit before and after the unbalanced bridge arm switching was analyzed by Ohm's law, and two mathematical relationships between the positive and negative bus insulation resistance and the positive and negative bus voltage to ground before and after the bridge arm switching were obtained. Then, the two relationships were combined to solve the positive and negative bus insulation resistance. However, this method only considers the bus voltage under ideal conditions, and does not analyze the white noise and pulse noise in the bus voltage and its measurement process, resulting in deviations in the calculation results.

[0005] 2) Reference 2 "Zhang Wei, Chu Jianxin, Song Weihao. Compensation of insulation resistance measurement error of DC power grid in hybrid power system [J]. Instrument Technology and Sensor, 2017 (8): 106-109." First, the insulation detection circuit before and after the unbalanced bridge arm switching is analyzed and modeled, and then multiple data are collected before and after the switching. The least squares method is used to identify the model parameters using the data set, and then the positive and negative bus insulation resistances are calculated using the identified parameters. However, this method requires the collection and storage of a large amount of data. If the collected data is small, the insulation resistance calculation is inaccurate, and online detection cannot be performed.

[0006] 3) Document 3, a utility model patent with patent publication number CN211698045U, discloses an electrical circuit insulation detection auxiliary device, which designs an electrical circuit insulation detection auxiliary device, which consists of an outer shell, a circuit board, a main control chip, a power supply, a power-on line detector, an acoustic emission detector, a thermal radiation detector, an electromagnetic emission detector, a signal converter, an alarm device and multiple signal monitoring connecting wires. However, the device has many external wiring materials and is not easy to carry. During detection, there are phenomena such as forgetting to bring wires or losing wires, and the device lacks self-calibration capability and cannot verify the impact of its own system errors and component aging on the measurement process.

[0007] In summary, the prior art has the following deficiencies:

[0008] 1) The white noise and pulse noise in the bus voltage and its measurement process are not considered, resulting in deviations in the calculation results of the bus insulation resistance;

[0009] 2) Using the least squares method to perform parameter identification and calculation to obtain the busbar insulation resistance requires a large amount of data and cannot be detected online.

[0010] 3) The insulation detection device is not easy to carry, has many wires, lacks self-calibration capability, and cannot verify the impact of its own system errors and component aging on the measurement process. Summary of the invention

[0011] The technical problem to be solved by the present invention is to propose a novel DC system busbar insulation resistance calculation method which is less affected by noise interference, requires less measurement data and can perform online detection.

[0012] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0013] A DC system insulation detection method, comprising:

[0014] S10, constructing a DC system bus insulation detection circuit and establishing a mathematical model of bus voltage and bus insulation resistance;

[0015] Among them, the busbar insulation detection circuit includes a busbar voltage detection circuit and a balanced bridge / unbalanced bridge control circuit; the busbar voltage detection circuit is provided with detection switches K4 and K12; the two ends of the detection switch K4 are respectively connected to the busbar positive pole and the grounding wire, and the two ends of the detection switch K12 are respectively connected to the grounding wire and the busbar negative pole; the balanced bridge / unbalanced bridge control circuit includes balanced bridge switches K5 and K13, and unbalanced bridge switches K6 and K14; the two ends of the balanced bridge switch K5 and the unbalanced bridge switch K6 are respectively connected to the busbar positive pole and the grounding wire, and the two ends of the balanced bridge switch K13 and the unbalanced bridge switch K14 are respectively connected to the grounding wire and the busbar negative pole;

[0016] S20, close the detection switches K4 and K12, the balanced bridge switches K5 and K13, and the unbalanced bridge switch K6, open the unbalanced bridge switch K14, and measure the voltage between the positive and negative busbars and the ground;

[0017] S30, after each measurement of the positive and negative bus voltages to ground, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method 1 ;

[0018] S40, keeping the states of other switches unchanged, disconnecting the unbalanced bridge switch K6, closing the switch K14, and measuring the voltages of the positive and negative busbars to ground;

[0019] S50, after each measurement of the positive and negative bus voltages to ground, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method 2 ;

[0020] S60, through the parameter to be identified θ 1 ,θ 2 , combined with the mathematical model of bus voltage and bus insulation resistance, calculate the positive and negative bus insulation resistance values.

[0021] In one embodiment of the present invention, a mathematical model of bus voltage and bus insulation resistance is established, including:

[0022] When the detection switches K4, K12, the balanced bridge switches K5, K13, and the unbalanced bridge switch K6 are closed, and the unbalanced bridge switch K14 is opened, the mathematical model of the bus voltage and the bus insulation resistance is as follows:

[0023] remember

[0024] Where U p1 is the bus positive pole to ground voltage under step S20, U n1 is the voltage of the negative pole of the busbar to the ground under the condition of step S20; K is the resistance ratio of the detection switch route, recorded as K=(R 1 +R 2 ) / (R 6 +R 10 ), R 4 is the positive unbalanced bridge resistance in the bus voltage detection circuit, R p3 The positive busbar insulation resistance R to be calculated p With the balanced bridge resistor R 3 The equivalent parallel resistance is denoted as R p3 =R p R 3 / (R p +R 3 ), R n7 The negative busbar insulation resistance R to be calculated nWith the balanced bridge resistor R 7 The equivalent parallel resistance is denoted as R n7 =R n R 7 / (R n +R 7 )R n7 .

[0025] In one embodiment of the present invention, a mathematical model of bus voltage and bus insulation resistance is established, including:

[0026] When the detection switches K4 and K12 are closed, the balanced bridge switches K5 and K13 are closed, the unbalanced bridge switch K6 is opened, and the unbalanced bridge switch K14 is closed, the mathematical model of the bus voltage and the bus insulation resistance is as follows:

[0027] remember

[0028] Where U p2 is the voltage of the positive busbar to ground under the condition of step S40, U n2 is the voltage between the negative bus and the ground under the condition of step S40, R 8 is the negative unbalanced bridge resistance; K is the detection switch line resistance ratio, recorded as K = (R 1 +R 2 ) / (R 6 +R 10 ), R 4 is the positive unbalanced bridge resistance in the bus voltage detection circuit, R p3 The positive busbar insulation resistance R to be calculated p With the balanced bridge resistor R 3 The equivalent parallel resistance is denoted as R p3 =R p R 3 / (R p +R 3 ), R n7 The negative busbar insulation resistance R to be calculated n With the balanced bridge resistor R 7 The equivalent parallel resistance is denoted as R n7 =R n R 7 / (R n +R 7 )R n7 .

[0029] In one embodiment of the present invention, in step S20, measuring the voltage of the positive and negative busbars to ground includes:

[0030] Disconnect the unbalanced bridge switch K6, close the unbalanced bridge switch K14, and measure the voltage of the positive and negative poles of the busbar to the ground at each moment, which are recorded as Up1 =[u p1 (1),...,u p1 (i),...,u p1 (n)] T , U n1 =[u n1 (1),...,u n1 (i),...,u n1 (n)] T Among them, u p1 (i) is the positive bus voltage to ground at the i-th measurement, u n1 (i) is the negative bus voltage to ground at the i-th measurement; and, T represents the matrix transpose; and n is the maximum number of measurements.

[0031] In one embodiment of the present invention, in step S30, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method. 1 ,include:

[0032] S31, calculate the prediction error e 1 (i);

[0033] After the i-th measurement, the positive bus voltage to ground u p1 (i) As the reference output, the negative bus voltage to ground u n1 (i) As input, calculate the model prediction error e 1 (i), where e 1 (i) = u p1 (i)-θ 1 (i-1)u n1 (i); where, θ 1 (i-1) represents the parameter θ to be identified during the i-1th measurement 1 ;

[0034] S32, update gain factor K 1 , covariance matrix P 1 , data reuse parameter α 1 , β 1 , bus voltage average With the regularization term L 1 ;

[0035] The gain factor calculation formula is: Where λ is the forgetting factor;

[0036] The formula for calculating the covariance matrix is:

[0037] The data reuse parameter calculation formula is: β 1 =(1-α1 m ) / (1-α 1 ), where m is the number of data reuses;

[0038] The calculation formula of bus voltage mean is:

[0039] The regularization term calculation formula is: Among them, μ 1 is the regularization term adjustment coefficient;

[0040] S33, update the parameter to be identified θ 1 (i);

[0041] The update formula of the parameter to be identified is: 1 (i) = θ 1 (i-1)+L 1 K 1 β 1 e 1 (i);

[0042] S34, repeating steps S31 to S33 until the measurement is stopped.

[0043] In one embodiment of the present invention, in step S40, measuring the voltage of the positive and negative busbars to ground includes:

[0044] Close the detection switches K4 and K12, the balance bridge switches K5 and K13, open the unbalanced bridge switch K6, close the unbalanced bridge switch K14, and measure the voltage of the positive and negative busbars to the ground at each moment, recorded as U p2 =[u p2 (1),...,u p2 (i),...,u p2 (n)] T , U n2 =[u n2 (1),...,u n2 (i),...,u n2 (n)] T ; Among them, u p2 (i) is the positive bus voltage to ground at the i-th measurement, u n2 (i) is the negative bus voltage to ground at the i-th measurement; T represents the matrix transpose; n is the maximum number of measurements.

[0045] In one embodiment of the present invention, in step S50, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method. 2 ,include:

[0046] S51, calculate the prediction error e 2 (i);

[0047] After the i-th measurement, the positive bus voltage to ground u p2 (i) As the reference output, the negative bus voltage to ground u n2 (i) As input, calculate the model prediction error e 2 (i), where e 2 (i) = u p2 (i)-θ 2 (i-1)u n2 (i); where, θ 2 (i-1) represents the parameter θ to be identified during the i-1th measurement 2 ;

[0048] S52, update gain factor K 2 , covariance matrix P 2 , data reuse parameter α 2 , β 2 , bus voltage average With the regularization term L 2 ;

[0049] The gain factor calculation formula is: Where λ is the forgetting factor;

[0050] The formula for calculating the covariance matrix is:

[0051] The data reuse parameter calculation formula is: β 2 =(1-α 2 m ) / (1-α 2 ), where m is the number of data reuses;

[0052] The calculation formula of bus voltage mean is:

[0053]

[0054] The regularization term calculation formula is: Among them, μ 2 is the regularization term adjustment coefficient;

[0055] S53, update the parameter to be identified θ 2 (i);

[0056] The update formula of the parameter to be identified is: 2 (i) = θ 2 (i-1)+L 2 K 2 β 2 e 2 (i);

[0057] S54, repeating steps S51 to S53 until the measurement is stopped.

[0058] In one embodiment of the present invention, in step S60, the insulation resistance values ​​of the positive and negative busbars are calculated by the following formula:

[0059] The parameter to be identified θ obtained in step S10 1 ,θ 2 The equivalent resistance R of the positive and negative busbar insulation resistance and the balance bridge resistance p3 , R n7 The mathematical relationship is solved together, and the calculation formula for the positive busbar insulation resistance is R p =R p3 R 3 / (R 3 -R p3 ), the negative busbar insulation resistance calculation formula is R n =R n7 R 7 / (R 7 -R n7 ), where R 3 , R 7 They are two series balanced bridge resistors, and R 3 The two ends of R are connected to the positive pole of the busbar and the ground wire respectively. 7 The two ends are connected to the ground wire and the negative pole of the busbar respectively.

[0060] The present invention also provides a portable DC system insulation detection and verification integrated device, comprising: a handheld meter, a leakage current collector and a verification and detection host; the leakage current collector and the verification and detection host are respectively wirelessly connected to the handheld meter;

[0061] Among them, the handheld meter is used for visualization and display of data obtained from the leakage current collector and the verification and detection host;

[0062] Leakage current collector, used to measure leakage current data;

[0063] The verification and detection host is used to measure bus data and integrate the DC system insulation detection method described above.

[0064] In one embodiment of the present invention, the verification and detection host also integrates a simulated ground resistance circuit, an AC series detection circuit, and a detection signal source circuit; wherein,

[0065] The analog grounding resistance circuit includes switches K1, K2, K3, K9, K10, K11, and resistors R11, R12, R13, R14, R15, and R16; the switch K1 is connected in series with the resistor R11 to form a first analog branch; the switch K2 is connected in series with the resistor R12 to form a second analog branch; the switch K3 is connected in series with the resistor R13 to form a third analog branch; the switch K9 is connected in series with the resistor R14 to form a fourth analog branch; the switch K10 is connected in series with the resistor R15 to form a fifth analog branch; the switch K11 is connected in series with the resistor R16 to form a sixth analog branch; and,

[0066] The two ends of the first simulation branch, the second simulation branch, and the third simulation branch are connected to the positive pole of the bus and the grounding wire respectively; the two ends of the fourth simulation branch, the fifth simulation branch, and the sixth simulation branch are connected to the grounding wire and the negative pole of the bus respectively; when the simulated grounding resistance circuit performs the grounding fault simulation verification function, all switches at the positive and negative poles of the bus are first disconnected; then, according to the polarity and resistance value of the simulated grounding verification, the switches K1, K2, K3 and K9, K10, K11 are controlled to be switched in combination, and the accuracy of the simulated grounding resistance measurement is verified by the resistors R11, R12, and R13 with given resistance values;

[0067] The AC series detection circuit includes switches K7 and K15, resistors R5 and R9, and capacitors C1 and C2; the switch K7, capacitor C1 and resistor R5 are connected in series in sequence, and the two ends are connected to the positive electrode of the bus and the ground wire respectively; the resistor R9, capacitor C2 and switch K15 are connected in series in sequence, and the two ends are connected to the ground wire and the negative electrode of the bus respectively; and the resistors R5 and R9 are connected to the AD digital-to-analog converter;

[0068] When the AC series-in detection circuit is working, the AC series-in detection circuit measurement function is connected between the positive or negative pole of the busbar and the ground, and switches K7 and K15 are closed, and the other switches on the busbar are disconnected. If there is an AC signal, the AD digital-to-analog converter will detect the voltage difference; if there is no AC signal, there will be no voltage difference;

[0069] The detection signal source circuit includes switches K8 and K16; the two ends of the switch K8 are respectively connected to the positive pole of the busbar and the ground wire, and the two ends of the switch K16 are respectively connected to the ground wire and the negative pole of the busbar;

[0070] Signal source injection control is performed during ground fault detection. When the detection signal source circuit detects that the insulation resistance of the positive electrode to the ground is too low, switch K16 is disconnected, switch K8 is closed, and the detection signal source is connected between the positive electrode of the DC bus and the ground wire to prepare for the positive ground fault detection. When the insulation resistance of the negative electrode to the ground is detected to be too low, switch K8 is disconnected, switch K16 is closed, and the detection signal source is connected between the negative electrode of the DC bus and the ground wire to prepare for the negative ground fault detection.

[0071] And, the leakage current collection circuit of the leakage current collector includes resistors R11, R22, R33, R44, R55, R00, R66, capacitor C3, operational amplifier U0, AD1 digital-to-analog converter, main controller MCU1, current clamp and switch kk;

[0072] One end of the switching switch kk is connected to the resistor R55 and then grounded, and the other end of the switching switch kk can be selectively connected to one of the resistors R11, R22, R33, and R44, and the resistance values ​​of the resistors R11, R22, R33, and R44 are different, forming a multi-way switch for multi-range switching;

[0073] The other ends of resistors R11, R22, R33, and R44 are connected to the output end of the operational amplifier U0; the output end of the operational amplifier U0 is also connected to the AD1 digital-to-analog converter and the main controller MCU1 in sequence; the main controller MCU1 is communicatively connected to the switching switch kk; the first input end of the operational amplifier U0 is connected to the connection end of the resistor R55 and the switching switch kk, and the second input end of the operational amplifier U0 is connected to the resistor R00 and the current clamp; and the resistor R66 and the capacitor C3 are connected in series and then connected in parallel with the resistor R00.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] Compared with the traditional Ohm's law detection algorithm, the regularized data reuse recursive least squares method proposed in the present invention designs a regularization term to penalize the noisy bus voltage data, thereby overcoming the shortcoming of the traditional Ohm's law detection algorithm that the calculation results are biased due to noise interference, and significantly improving the calculation accuracy.

[0076] Compared with the least squares algorithm, the regularized data reuse recursive least squares method proposed in the present invention only uses the current data to update parameters in a recursive manner, which is suitable for online real-time processing. Through data reuse technology, data utilization is effectively improved, overcoming the problem of inaccurate identification of the least squares algorithm when the data sample size is limited.

[0077] The core idea of ​​data reuse of the present invention is to use the input and output data of the current time step to iterate repeatedly, so as to obtain a better identification parameter with less data. In terms of regularization, the regularization factor of the present invention is used to measure the degree of data abnormality. The core is to punish the noise data and reduce the influence of the noise data on the identification parameters during the iteration process.

[0078] Wireless communication is adopted to reduce the use of external wiring materials, making it easier to carry the integrated insulation detection and verification equipment. By combining the switching switch to simulate the busbar insulation resistance, the ground fault simulation verification is realized to verify the influence of the system error and component aging on the measurement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 The present invention is a flow chart of a DC system insulation detection method according to an embodiment of the present invention.

[0080] Figure 2 FIG. 1 is a hardware implementation diagram of the verification detection host principle of an embodiment of the present invention

[0081] Figure 3 The present invention is a block diagram of a portable DC system insulation detection and verification integrated device according to an embodiment of the present invention.

[0082] Figure 4 This is a schematic diagram of a leakage current collector circuit for collecting leakage current according to an embodiment of the present invention.

[0083] Figure 5 This is a comparison chart of simulation results between the regularized data reuse recursive least squares method of an embodiment of the present invention and the traditional Ohm's law detection algorithm.

[0084] Figure 6 This is a comparison chart of simulation results between the regularized data reuse recursive least squares method of an embodiment of the present invention and the traditional Ohm's law detection algorithm. DETAILED DESCRIPTION

[0085] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings of the specification.

[0086] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0087] See also Figure 1 As shown, the present invention discloses a DC system insulation detection method, comprising:

[0088] S10, constructing a DC system bus insulation detection circuit and establishing a mathematical model of bus voltage and bus insulation resistance.

[0089] See also Figure 2As shown, in one embodiment of the present invention, a DC system busbar insulation detection circuit is constructed, a circuit analysis is performed on the busbar insulation detection circuit, a mathematical relationship between the positive and negative busbar voltages to ground and the positive and negative busbar insulation resistances is established, and a mathematical model of the positive and negative busbar voltages to ground is obtained. The busbar insulation detection circuit includes a busbar voltage detection circuit and a balanced bridge / unbalanced bridge control circuit.

[0090] In this embodiment, the bus voltage detection circuit includes detection switches K4 and K12, resistors R1, R2, R6, and R10. After the detection switch K4 is connected in series with the resistors R1 and R2, the two ends are connected to the positive electrode of the bus and the ground wire respectively. After the resistors R6 and R10 are connected in series with the detection switch K12, the two ends are connected to the ground wire and the negative electrode of the bus respectively.

[0091] In this embodiment, the balanced bridge / unbalanced bridge control circuit includes a balanced bridge circuit and an unbalanced bridge circuit. Among them, the balanced bridge circuit includes balanced bridge switches K5 and K13, and resistors R3 and R7. After the balanced bridge switch K5 and the resistor R3 are connected in series, the two ends are connected to the positive pole of the bus and the ground wire respectively. After the resistor R7 and the balanced bridge switch K13 are connected in series, the two ends are connected to the ground wire and the negative pole of the bus respectively. The unbalanced bridge circuit includes unbalanced bridge switches K6 and K14, resistors R4 and R8. After the unbalanced bridge switch K6 and the resistor R4 are connected in series, the two ends are connected to the positive pole of the bus and the ground wire respectively. After the resistor R8 and the unbalanced bridge switch K14 are connected in series, the two ends are connected to the ground wire and the negative pole of the bus respectively.

[0092] In this embodiment, a mathematical model of bus voltage and bus insulation resistance is established, including:

[0093] When the detection switches K4, K12, the balanced bridge switches K5, K13, and the unbalanced bridge switch K6 are closed, and the unbalanced bridge switch K14 is opened, the mathematical model of the bus voltage and the bus insulation resistance is as follows:

[0094] remember

[0095] Where U p1 Under this condition, the bus positive pole to ground voltage, U n1 is the voltage of the negative pole of the busbar to the ground under the condition of step S20; K is the resistance ratio of the detection switch route, recorded as K=(R 1 +R 2 ) / (R 6 +R 10 ), R 4 is the positive unbalanced bridge resistance in the bus voltage detection circuit, R p3 The positive busbar insulation resistance R to be calculated p With the balanced bridge resistor R 3 The equivalent parallel resistance is denoted as Rp3 =R p R 3 / (R p +R 3 ), R n7 The negative busbar insulation resistance R to be calculated n With the balanced bridge resistor R 7 The equivalent parallel resistance is denoted as R n7 =R n R 7 / (R n +R 7 )R n7 .

[0096] When the detection switches K4 and K12, the balanced bridge switches K5 and K13 are closed, the unbalanced bridge switch K6 is opened, and the unbalanced bridge switch K14 is closed, the mathematical model of the bus voltage and the bus insulation resistance is as follows;

[0097] remember

[0098] Where U p2 Under this condition, the positive bus voltage to ground, U n2 is the voltage between the negative bus and the ground under the condition of step S40, R 8 is the negative unbalanced bridge resistance.

[0099] S20, close the detection switches K4, K12, the balanced bridge switches K5, K13, and the unbalanced bridge switch K6, open the unbalanced bridge switch K14, and measure the positive and negative bus voltages to ground.

[0100] In one embodiment of the present invention, measuring the voltage of the positive and negative busbars to ground includes:

[0101] Disconnect the unbalanced bridge switch K6, close the unbalanced bridge switch K14, and measure the voltage of the positive and negative poles of the busbar to the ground at each moment, which are recorded as U p1 =[u p1 (1),...,u p1 (i),...,u p1 (n)] T , U n1 =[u n1 (1),...,u n1 (i),...,u n1 (n)] T Among them, u p1 (i) is the positive bus voltage to ground at the i-th measurement, u n1 (i) is the negative bus voltage to ground at the i-th measurement. And where T represents the matrix transpose and n is the maximum number of measurements.

[0102] S30, after each measurement of the positive and negative bus voltages to ground, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method 1 .

[0103] In one embodiment of the present invention, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method. 1 ,include:

[0104] S31, calculate the prediction error e 1 (i).

[0105] After the i-th measurement, the positive bus voltage to ground u p1 (i) As the reference output, the negative bus voltage to ground u n1 (i) As input, calculate the model prediction error e 1 (i), where e 1 (i) = u p1 (i)-θ 1 (i-1)u n1 (i). Among them, θ 1 (i-1) represents the parameter θ to be identified during the i-1th measurement 1 .

[0106] S32, update gain factor K 1 , covariance matrix P 1 , data reuse parameter α 1 , β 1 , bus voltage average With the regularization term L 1 .

[0107] The gain factor calculation formula is: Where λ is the forgetting factor.

[0108] The formula for calculating the covariance matrix is:

[0109] The data reuse parameter calculation formula is: β 1 =(1-α 1 m ) / (1-α 1 ), where m is the number of data reuses.

[0110] The calculation formula of bus voltage mean is:

[0111] The regularization term calculation formula is: Among them, μ 1 is the regularization term adjustment coefficient.

[0112] S33, update the parameter to be identified θ 1 (i).

[0113] The update formula of the parameter to be identified is: 1 (i) = θ 1 (i-1)+L 1 K 1 β 1 e 1 (i).

[0114] S34, repeating steps S31 to S33 until the measurement is stopped.

[0115] S40, keeping the states of other switches unchanged, disconnecting the unbalanced bridge switch K6, closing the switch K14, and measuring the voltages of the positive and negative busbars to ground.

[0116] In one embodiment of the present invention, measuring the voltage of the positive and negative busbars to ground includes:

[0117] Close the detection switches K4 and K12, the balance bridge switches K5 and K13, open the unbalanced bridge switch K6, close the unbalanced bridge switch K14, and measure the voltage of the positive and negative busbars to the ground at each moment, recorded as U p2 =[u p2 (1),...,u p2 (i),...,u p2 (n)] T , U n2 =[u n2 (1),...,u n2 (i),...,u n2 (n)] T Among them, u p2 (i) is the positive bus voltage to ground at the i-th measurement, u n2 (i) is the negative bus voltage to ground during the i-th measurement.

[0118] S50, after each measurement of the positive and negative bus voltages to ground, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method 2 .

[0119] In one embodiment of the present invention, the parameter to be identified θ is updated by using the regularized data reuse recursive least squares method. 2 ,include:

[0120] S51, calculate the prediction error e 2 (i).

[0121] After the i-th measurement, the positive bus voltage to ground u p2 (i) As the reference output, the negative bus voltage to ground u n2(i) As input, calculate the model prediction error e 2 (i), where e 2 (i) = u p2 (i)-θ 2 (i-1)u n2 (i); where, θ 2 (i-1) represents the parameter θ to be identified during the i-1th measurement 2 .

[0122] S52, update gain factor K 2 , covariance matrix P 2 , data reuse parameter α 2 , β 2 , bus voltage average With the regularization term L 2 .

[0123] The gain factor calculation formula is: Where λ is the forgetting factor.

[0124] The formula for calculating the covariance matrix is:

[0125] The data reuse parameter calculation formula is: β 2 =(1-α 2 m ) / (1-α 2 ), where m is the number of data reuses.

[0126] The calculation formula of bus voltage mean is:

[0127] The regularization term calculation formula is: Among them, μ 2 is the regularization term adjustment coefficient.

[0128] S53, update the parameter to be identified θ 2 (i).

[0129] The update formula of the parameter to be identified is: 2 (i) = θ 2 (i-1)+L 2 K 2 β 2 e 2 (i).

[0130] S54, repeating steps S51 to S53 until the measurement is stopped.

[0131] S60, through the parameter to be identified θ 1 ,θ 2, combined with the mathematical model of bus voltage and bus insulation resistance, calculate the positive and negative bus insulation resistance values.

[0132] In one embodiment of the present invention, the parameter to be identified θ obtained in step S10 1 ,θ 2 The equivalent resistance R of the positive and negative busbar insulation resistance and the balance bridge resistance p3 , R n7 The mathematical relationship is solved together, and the equivalent resistance calculation formula is:

[0133] R p3 =(θ 2 -θ 1 )R 4 R 8 / (KR 4 +θ 1 R 8 ), R n7 =(θ 2 -θ 1 )KR 4 R 8 / (θ 1 (KR 4 +θ 2 R 8 )).but

[0134] The calculation formula of positive busbar insulation resistance is R p =R p3 R 3 / (R 3 -R p3 ), the negative busbar insulation resistance calculation formula is R n =R n7 R 7 / (R 7 -R n7 ).

[0135] See also Figure 3 As shown, the present invention also provides a portable DC system insulation detection and verification integrated device, including: a handheld meter 10, a leakage current collector 20 and a verification and detection host 30. The leakage current collector 20 and the verification and detection host 30 are respectively wirelessly connected to the handheld meter 10. There is no direct communication between the leakage current collector 20 and the verification and detection host 30. And the verification and detection host 30 integrates the DC system insulation detection method described above.

[0136] In this embodiment, the handheld meter 10 is used for visualization and display of data obtained from the leakage current collector and the calibration and detection host. The handheld meter 10 can be implemented by purchasing an industrial-grade tablet. The industrial tablet is pre-installed with the Android operating system, and the hardware configuration is 6.21 inches, with a resolution of 1520*720 display screen. Industrial-grade capacitive screen, supporting wet hand operation / gesture operation / multi-touch / glove mode. 8-core 2.0GHz high-performance processor, 64G ROM+4G RAM memory. Built-in 2G / 3G4G / 5G, wifi, Bluetooth wireless communication interface, GPS / AGPS / Beidou / Galileo / GLONASS / QZSS / GNSS multi-mode positioning system, supporting one-dimensional / two-dimensional barcode scanning and other functions. The software adopts JAVA language and is implemented by developing Android APP. Android APP mainly includes current collector management module, calibration analyzer management module, communication module, collection data processing module, data and curve display module, key processing module, historical data and report management module, system configuration module, etc.

[0137] In this embodiment, the leakage current collector 20 is used to measure the leakage current data. The hardware of the leakage current collector 20 is composed of a main control MCU, a Bluetooth communication module, a current transformer, a signal grading amplification module, a filtering module, an analog-to-digital conversion module, a battery management module, a power on / off and status indication part. The acquisition software uses C language to develop the MCU program, realizes receiving host commands and data unpacking processing, command response sending through wireless communication, controls the analog-to-digital conversion module to collect current data, performs calculation processing and waveform recording on the collected data, realizes the current acquisition circuit calibration function, battery power monitoring and low power consumption management, collector power on / off key scanning and processing, collector working status indication and other functions.

[0138] See also Figure 4 As shown, in this embodiment, specifically, the leakage current collection circuit of the leakage current collector includes resistors R11, R22, R33, R44, R55, R00, R66, capacitor C3, operational amplifier U0, AD1 digital-to-analog converter, main controller MCU1, current clamp and switching switch kk.

[0139] One end of the switching switch kk is connected to the resistor R55 and then grounded, and the other end of the switching switch kk can be selectively connected to one end of the resistors R11, R22, R33, and R44, and the resistance values ​​of the resistors R11, R22, R33, and R44 are different, forming a multi-way switch with multi-range switching.

[0140] And the other ends of resistors R11, R22, R33, and R44 are connected to the output end of the operational amplifier U0. And the output end of the operational amplifier U0 is also connected to the AD1 digital-to-analog converter and the main controller MCU1 in sequence. And the main controller MCU1 is connected to the switching switch kk in communication. The first input end of the operational amplifier U0 is connected to the connection end of the resistor R55 and the switching switch kk, and the second input end of the operational amplifier U0 is connected to the resistor R00 and the current clamp. And, the resistor R66 and the capacitor C3 are connected in series and then connected in parallel with the resistor R00.

[0141] In this embodiment, the leakage current acquisition circuit realizes the multi-range automatic switching function through the current clamp and the multi-way switch, ensuring that the measurement circuit and the current size are in the best adaptation state, and improving the measurement accuracy of the system. At the same time, the acquisition circuit is configured with a filtering link to filter out signals of 50Hz and above frequency bands to avoid excessive signal input causing saturation of the measurement amplifier circuit and failure to measure useful low-frequency current signals. The specific working principle is as follows:

[0142] The leakage current input current i, according to Kirchhoff's current-voltage law and the virtual short and virtual break principle of the operational amplifier: u2=u1=i*R00,

[0143] Where j = 11, 22, 33, 44. The switching of R11, R22, R33, and R44 is realized through a multi-way switch. The voltage input to the AD1 digital-to-analog converter is obtained by combining the solutions. The data collected by the AD1 digital-to-analog converter is sent to the main controller MCU1, which switches the multi-way switch to change the R j Resistance value, thereby achieving multi-range switching for leakage current i of different sizes.

[0144] See also Figure 2 As shown, in one embodiment of the present invention, the verification and detection host 30 includes a main control MCU, a wireless communication module, an analog-to-digital conversion module, a power module, a bus voltage detection circuit, a balanced bridge / unbalanced bridge control circuit, an analog grounding resistance circuit, an AC series detection circuit, a detection signal source circuit, an LED status indication, etc. The software is designed using a single-chip microcomputer program, including a wireless communication part, analog-to-digital conversion control, calculation of bus voltage, positive and negative bus voltage to ground, calculation of positive and negative bus insulation resistance to ground, calculation of bus capacitance to ground, calculation of bus AC voltage, injection of bus signal amplitude, frequency control, verification resistance control output, LED status indication, etc.

[0145] In this embodiment, the verification and detection host 30 has three external terminals, which are connected to the positive pole of the DC system bus, the negative pole of the bus and the ground respectively. The three input and output terminals provide power for the normal operation of the verification and detection host 30, and also provide an input circuit for signal detection and an output circuit for signal injection.

[0146] In this embodiment, the bus positive and negative voltages, the bus positive voltage to ground and the bus negative voltage to ground are sampled by the bus voltage detection circuit and then sent to AD conversion and MCU data processing.

[0147] In this embodiment, the analog grounding resistance circuit includes switches K1, K2, K3, K9, K10, K11, and resistors R11, R12, R13, R14, R15, and R16. The switch K1 is connected in series with the resistor R11 to form a first analog branch; the switch K2 is connected in series with the resistor R12 to form a second analog branch. The switch K3 is connected in series with the resistor R13 to form a third analog branch. The switch K9 is connected in series with the resistor R14 to form a fourth analog branch. The switch K10 is connected in series with the resistor R15 to form a fifth analog branch. The switch K11 is connected in series with the resistor R16 to form a sixth analog branch.

[0148] In this embodiment, the two ends of the first simulation branch, the second simulation branch, and the third simulation branch are connected to the positive pole of the bus and the grounding wire, respectively. The two ends of the fourth simulation branch, the fifth simulation branch, and the sixth simulation branch are connected to the grounding wire and the negative pole of the bus, respectively. When the simulated grounding resistance circuit performs the grounding fault simulation verification function, all switches at the positive and negative poles of the bus are first disconnected. Then, according to the polarity and resistance value of the simulated grounding verification, the switches K1, K2, K3 and K9, K10, K11 are controlled to be switched in combination, and the accuracy of the simulated grounding resistance measurement is verified by the resistors R11, R12, and R13 with given resistance values.

[0149] In this embodiment, the AC series detection circuit includes switches K7 and K15, resistors R5 and R9, and capacitors C1 and C2. The switch K7, capacitor C1, and resistor R5 are connected in series in sequence, and the two ends are connected to the positive pole of the bus and the ground line respectively. The resistor R9, capacitor C2, and switch K15 are connected in series in sequence, and the two ends are connected to the ground line and the negative pole of the bus respectively. And, resistors R5 and R9 are connected to the AD digital-to-analog converter.

[0150] In this embodiment, when the AC series-in detection circuit is working, the AC series-in detection circuit measurement function is connected between the positive or negative pole of the bus and the ground, and switches K7 and K15 are closed, and the remaining switches on the bus are disconnected. If there is an AC signal, the AD digital-to-analog converter will detect the voltage difference, and if there is no series-in, there is no voltage difference. The sampling circuit uses capacitors to isolate DC to prevent DC signals from affecting the accuracy of AC sampling.

[0151] In this embodiment, the detection signal source circuit includes switches K8 and K16. The two ends of switch K8 are connected to the positive pole of the bus and the ground wire respectively, and the two ends of switch K16 are connected to the ground wire and the negative pole of the bus respectively. When the ground fault is found, the signal source is injected into the control. When the detection signal source circuit detects that the insulation resistance of the positive pole to the earth is too low, the switch K16 is disconnected, the switch K8 is closed, and the detection signal source is connected between the positive pole of the DC bus and the ground wire to prepare to find the positive pole ground fault. When it is detected that the insulation resistance of the negative pole to the earth is too low, the switch K8 is disconnected, the switch K16 is closed, and the detection signal source is connected between the negative pole of the DC bus and the ground wire to prepare to find the negative pole ground fault. When the insulation resistance of the positive and negative poles to the earth is too low at the same time, the one pole with too low insulation resistance is detected first, and the other pole is detected after eliminating the fault of one pole. When the insulation resistance of the positive and negative poles to the earth is too low at the same time, and the insulation resistance is almost equal, the positive pole ground fault is detected first, and then the negative pole ground fault is detected.

[0152] See also Figures 1 to 4 As shown, in one embodiment of the present invention, in order to verify the effectiveness of the DC system insulation detection method of the present invention, a simulation verification is performed. In this example, the DC system insulation detection scheme circuit simulation and applied noise parameters are shown in Table 1:

[0153] Table 1 DC system insulation detection scheme circuit simulation and applied noise parameters

[0154] Parameter name Parameter Value Simulation time 5(s) Switching time 2.55(s) Simulation sampling time 0.1(s) Positive and negative bus voltage to ground U 117(V) <![CDATA[Balanced bridge resistors R 3 and R 7 > 30k(Ω) <![CDATA[Unbalanced bridge resistors R 4 and R 8 > 120k(Ω) <![CDATA[Positive electrode insulation resistance value R x > 150k(Ω) <![CDATA[Negative electrode insulation resistance value R y > 60k(Ω) White noise mean and variance 0、0.04 Impulse noise occurrence probability and amplitude 0.05、2

[0155] In this example, the initial parameter settings of the regularized data reuse recursive least squares method are shown in Table 2:

[0156] Table 2 Initial parameter setting table of regularized data reuse recursive least squares method

[0157] Parameter name Parameter Value Parameters to be identified θ 0 Covariance matrix P

[1000] Data reuse times m 5 Forgetting factor λ 1 Regularization term adjustment coefficient μ 15.0

[0158] During the simulation, the random seeds of white noise and impulse noise applied each time are different, and the intensity of impulse noise is different to increase the diversity of the experiment, so as to verify the robustness of the algorithm. A total of 20 experiments were conducted according to the parameters in Table 1 and Table 2, and the calculation results were compared with other algorithms.

[0159] Figure 5 This is a comparison chart of the simulation results of the regularized data reuse recursive least squares method and the traditional Ohm's method. Figure 6This is a comparison chart of the simulation results of the regularized data reuse recursive least squares method and the traditional least squares method. Through calculation, it is known that the mean square errors of the positive and negative busbar insulation resistances of the traditional Ohm's method are 67.86 and 3.38, the mean square errors of the traditional least squares method are 68.83 and 3.15, and the mean square errors of the regularized data reuse recursive least squares method are 27.86 and 1.39. By comparison, it can be seen that the regularized data reuse recursive least squares method proposed in the present invention is less affected by noise interference, which improves the calculation accuracy, and the fluctuations of the insulation resistance calculation results of multiple experiments are much smaller than those of the traditional Ohm's method and the least squares method, and has higher stability.

[0160] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0161] The above-described embodiments merely represent implementation methods of the invention. The protection scope of the present invention is not limited to the above-described embodiments. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A DC system insulation detection method, characterized in that: include: S10, constructing a DC system bus insulation detection circuit and establishing a mathematical model of bus voltage and bus insulation resistance; Among them, the busbar insulation detection circuit includes a busbar voltage detection circuit and a balanced bridge / unbalanced bridge control circuit; the busbar voltage detection circuit is provided with detection switches K4 and K12; the two ends of the detection switch K4 are respectively connected to the busbar positive pole and the grounding wire, and the two ends of the detection switch K12 are respectively connected to the grounding wire and the busbar negative pole; the balanced bridge / unbalanced bridge control circuit includes balanced bridge switches K5 and K13, and unbalanced bridge switches K6 and K14; the two ends of the balanced bridge switch K5 and the unbalanced bridge switch K6 are respectively connected to the busbar positive pole and the grounding wire, and the two ends of the balanced bridge switch K13 and the unbalanced bridge switch K14 are respectively connected to the grounding wire and the busbar negative pole; S20, close the detection switches K4 and K12, the balanced bridge switches K5 and K13, and the unbalanced bridge switch K6, open the unbalanced bridge switch K14, and measure the voltage between the positive and negative busbars and the ground; S30, after each measurement of the positive and negative busbar-to-ground voltages, the parameter to be identified θ1 is updated by using the regularized data reuse recursive least squares method; S40, keeping the states of other switches unchanged, disconnecting the unbalanced bridge switch K6, closing the switch K14, and measuring the voltages of the positive and negative busbars to ground; S50, after each measurement of the positive and negative bus voltages to ground, the parameter to be identified θ2 is updated by using a regularized data reuse recursive least squares method; S60, calculating the positive and negative bus insulation resistance values ​​by using the parameters to be identified θ1 and θ2 and combining the mathematical model of the bus voltage and the bus insulation resistance.

2. The DC system insulation detection method according to claim 1, characterized in that: Establish a mathematical model of bus voltage and bus insulation resistance, including: When the detection switches K4, K12, the balanced bridge switches K5, K13, and the unbalanced bridge switch K6 are closed, and the unbalanced bridge switch K14 is opened, the mathematical model of the bus voltage and the bus insulation resistance is as follows: remember Where U p1 is the bus positive pole to ground voltage under step S20, U n1 is the voltage of the negative pole of the busbar to the ground under the condition of step S20; K is the resistance ratio of the detection switch route, which is K=(R1+R2) / (R6+R 10 ), R4 is the positive unbalanced bridge resistance in the bus voltage detection circuit, R p3 The positive busbar insulation resistance R to be calculated p The equivalent parallel resistance of the balanced bridge resistor R3 is denoted as R p3 =R p R3 / (R p +R3), R n7 The negative busbar insulation resistance R to be calculated n The equivalent parallel resistance of the balanced bridge resistor R7 is denoted as R n7 =R n R7 / (R n +R7)R n7 .

3. The DC system insulation detection method according to claim 1, characterized in that: Establish a mathematical model of bus voltage and bus insulation resistance, including: When the detection switches K4 and K12 are closed, the balanced bridge switches K5 and K13 are closed, the unbalanced bridge switch K6 is opened, and the unbalanced bridge switch K14 is closed, the mathematical model of the bus voltage and the bus insulation resistance is as follows: remember Where U p2 is the voltage of the positive busbar to ground under the condition of step S40, U n2 is the voltage between the negative busbar and the ground under the condition of step S40, R8 is the resistance value of the negative unbalanced bridge resistor; K is the resistance ratio of the detection switch route, which is recorded as K=(R1+R2) / (R6+R 10 ), R4 is the positive unbalanced bridge resistance in the bus voltage detection circuit, R p3 The positive busbar insulation resistance R to be calculated p The equivalent parallel resistance of the balanced bridge resistor R3 is denoted as R p3 =R p R3 / (R p +R3), R n7 The negative busbar insulation resistance R to be calculated n The equivalent parallel resistance of the balanced bridge resistor R7 is denoted as R n7 =R n R7 / (R n +R7)R n7 .

4. The DC system insulation detection method according to claim 1, characterized in that: In step S20, measuring the voltage of the positive and negative busbars to ground includes: Disconnect the unbalanced bridge switch K6, close the unbalanced bridge switch K14, and measure the voltage of the positive and negative poles of the busbar to the ground at each moment, which are recorded as U p1 =[u p1 (1),...,u p1 (i),...,u p1 (n)] T , U n1 =[u n1 (1),...,u n1 (i),...,u n1 (n)] T Among them, u p1 (i) is the positive bus voltage to ground at the i-th measurement, u n1 (i) is the negative bus voltage to ground at the i-th measurement; and, T represents the matrix transpose; and n is the maximum number of measurements.

5. The DC system insulation detection method according to claim 1, characterized in that: In step S30, the parameter to be identified θ1 is updated by using the regularized data reuse recursive least squares method, including: S31, calculating the prediction error e1(i); After the i-th measurement, the positive bus voltage to ground u p1 (i) As the reference output, the negative bus voltage to ground u n1 (i) as input, calculate the model prediction error e1(i), where e1(i) = u p1 (i)-θ1(i-1)u n1 (i); where θ1(i-1) represents the parameter θ1 to be identified at the i-1th measurement; S32, update gain factor K1, covariance matrix P1, data reuse parameters α1, β1, bus voltage mean and regularization term L1; The gain factor calculation formula is: Where λ is the forgetting factor; The formula for calculating the covariance matrix is: The data reuse parameter calculation formula is: β1=(1-α1 m ) / (1-α1); where m is the number of data reuses; The calculation formula of bus voltage mean is: The regularization term calculation formula is: Among them, μ1 is the regularization term adjustment coefficient; S33, update the parameter to be identified θ1(i); The update formula of the parameters to be identified is: θ1(i) = θ1(i-1) + L1K1β1e1(i); S34, repeating steps S31 to S33 until the measurement is stopped.

6. The DC system insulation detection method according to claim 1, characterized in that: In step S40, measuring the voltage of the positive and negative busbars to ground includes: Close the detection switches K4 and K12, the balance bridge switches K5 and K13, open the unbalanced bridge switch K6, close the unbalanced bridge switch K14, and measure the voltage of the positive and negative busbars to the ground at each moment, recorded as U p2 =[u p2 (1),...,u p2 (i),...,u p2 (n)] T , U n2 =[u n2 (1),...,u n2 (i),...,u n2 (n)] T ; Among them, u p2 (i) is the positive bus voltage to ground at the i-th measurement, u n2 (i) is the negative bus voltage to ground at the i-th measurement; T represents the matrix transpose; n is the maximum number of measurements.

7. The DC system insulation detection method according to claim 1, characterized in that: In step S50, the parameter to be identified θ2 is updated by using the regularized data reuse recursive least squares method, including: S51, calculating the prediction error e2(i); After the i-th measurement, the positive bus voltage to ground u p2 (i) As the reference output, the negative bus voltage to ground u n2 (i) as input, calculate the model prediction error e2(i), where e2(i) = u p2 (i)-θ2(i-1)u n2 (i); where θ2(i-1) represents the parameter θ2 to be identified at the i-1th measurement; S52, update gain factor K2, covariance matrix P2, data reuse parameters α2, β2, bus voltage mean and regularization term L2; The gain factor calculation formula is: Where λ is the forgetting factor; The formula for calculating the covariance matrix is: The data reuse parameter calculation formula is: β2=(1-α2 m ) / (1-α2); where m is the number of data reuses; The calculation formula of bus voltage mean is: The regularization term calculation formula is: Among them, μ2 is the regularization term adjustment coefficient; S53, update the parameter to be identified θ2(i); The update formula of the parameters to be identified is: θ2(i) = θ2(i-1) + L2K2β2e2(i); S54, repeating steps S51 to S53 until the measurement is stopped.

8. The DC system insulation detection method according to claim 1, characterized in that: In step S60, the insulation resistance values ​​of the positive and negative busbars are calculated by the following formula: The parameters to be identified θ1, θ2 obtained in step S10 and the equivalent resistance R of the positive and negative bus insulation resistances and the balance bridge resistance are calculated. p3 , R n7 The mathematical relationship is solved together, and the calculation formula for the positive busbar insulation resistance is R p =R p3 R3 / (R3-R p3 ), the negative busbar insulation resistance calculation formula is R n =R n7 R7 / (R7-R n7 ), wherein R3 and R7 are two series-connected balanced bridge resistors, and both ends of R3 are connected to the positive electrode of the bus and the ground wire, respectively, and both ends of R7 are connected to the ground wire and the negative electrode of the bus.

9. A portable DC system insulation detection and verification integrated device, characterized in that: include: Handheld meter, leakage current collector and calibration and detection host; The leakage current collector and the verification and detection host are respectively connected with the handheld meter by wireless communication; Among them, the handheld meter is used for visualization and display of data obtained from the leakage current collector and the verification and detection host; Leakage current collector, used to measure leakage current data; A verification and detection host is used to measure bus data and integrate the DC system insulation detection method described in any one of claims 1-8.

10. The portable DC system insulation detection and verification integrated device according to claim 9, characterized in that: The verification and detection host also integrates a simulated ground resistance circuit, an AC series detection circuit, and a detection signal source circuit; among them, The analog grounding resistance circuit includes switches K1, K2, K3, K9, K10, K11, and resistors R11, R12, R13, R14, R15, and R16; the switch K1 is connected in series with the resistor R11 to form a first analog branch; the switch K2 is connected in series with the resistor R12 to form a second analog branch; the switch K3 is connected in series with the resistor R13 to form a third analog branch; the switch K9 is connected in series with the resistor R14 to form a fourth analog branch; the switch K10 is connected in series with the resistor R15 to form a fifth analog branch; the switch K11 is connected in series with the resistor R16 to form a sixth analog branch; and, The two ends of the first simulation branch, the second simulation branch, and the third simulation branch are respectively connected to the positive electrode of the busbar and the ground wire; the two ends of the fourth simulation branch, the fifth simulation branch, and the sixth simulation branch are respectively connected to the ground wire and the negative electrode of the busbar; The AC series detection circuit includes switches K7 and K15, resistors R5 and R9, and capacitors C1 and C2; the switch K7, capacitor C1 and resistor R5 are connected in series in sequence, and the two ends are connected to the positive electrode of the bus and the ground wire respectively; the resistor R9, capacitor C2 and switch K15 are connected in series in sequence, and the two ends are connected to the ground wire and the negative electrode of the bus respectively; and the resistors R5 and R9 are connected to the AD digital-to-analog converter; The detection signal source circuit includes switches K8 and K16; the two ends of the switch K8 are respectively connected to the positive pole of the busbar and the ground wire, and the two ends of the switch K16 are respectively connected to the ground wire and the negative pole of the busbar; And, the leakage current collection circuit of the leakage current collector includes resistors R11, R22, R33, R44, R55, R00, R66, capacitor C3, operational amplifier U0, AD1 digital-to-analog converter, main controller MCU1, current clamp and switch kk; One end of the switching switch kk is connected to the resistor R55 and then grounded, and the other end of the switching switch kk can be selectively connected to one of the resistors R11, R22, R33, and R44, and the resistance values ​​of the resistors R11, R22, R33, and R44 are different, forming a multi-way switch for multi-range switching; The other ends of resistors R11, R22, R33, and R44 are connected to the output end of the operational amplifier U0; the output end of the operational amplifier U0 is also connected to the AD1 digital-to-analog converter and the main controller MCU1 in sequence; the main controller MCU1 is communicatively connected to the switching switch kk; the first input end of the operational amplifier U0 is connected to the connection end of the resistor R55 and the switching switch kk, and the second input end of the operational amplifier U0 is connected to the resistor R00 and the current clamp; and the resistor R66 and the capacitor C3 are connected in series and then connected in parallel with the resistor R00.

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