DC side insulation resistance detection circuit and detection method of energy storage converter

Abstract

The invention provides an energy storage converter DC side insulation resistance detection circuit and detection method, and the circuit comprises a first switch resistor, a first matching switch, a first fixed value resistor, a second switch resistor, a second matching switch, a second fixed value resistor, and a third fixed value resistor. The first switch resistor and the first fixed-value resistor are connected in series between a positive bus and a grounding wire, the first matching switch is connected to two ends of the first switch resistor, and the third fixed-value resistor is connected in parallel with the first switch resistor and the first fixed-value resistor and is connected between the positive bus and the grounding wire; the second switch resistor and the second fixed value resistor are connected between the negative bus and the grounding wire. The second matching switch is connected to the two ends of the second switch resistor. The positive bus voltage and the negative bus voltage are sampled to determine the insulation resistance, the problem of insufficient sampling due to too low voltage is effectively prevented, and the accuracy of insulation resistance detection is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage converter equipment, and in particular to a DC side insulation resistance detection circuit and a detection method for an energy storage converter. Background Art

[0002] With the widespread application of renewable energy and the development of smart grids, energy storage technology has become increasingly important. As an important component of the energy storage system, the performance and safety of the energy storage converter are crucial. However, in practical applications, insulation failures of energy storage converters often occur due to various reasons (such as equipment aging, environmental erosion, etc.), which may lead to equipment damage, decreased system stability, and even personnel safety issues. Therefore, designing an effective DC side insulation resistance detection circuit for energy storage converters to promptly detect and deal with insulation problems is of great significance for ensuring the safe and stable operation of the system. With the rapid development of my country's economy, the country's vigorous development of distributed energy is an effective way to solve the current global resource shortage and environmental pollution problems.

[0003] In the prior art, grounding detection equipment is usually designed for a specific type of AC converter or system, with poor versatility, and detection accuracy and response speed need to be improved. Therefore, it is very important to design a DC side insulation resistance detection circuit for energy storage converters that is highly versatile, highly accurate, fast in response speed, and easy to implement. To this end, the present invention proposes a DC side insulation resistance detection circuit for energy storage converters. Summary of the invention

[0004] The purpose of the present invention is to provide a DC side insulation resistance detection circuit and detection method for an energy storage converter, so as to solve the problems that current grounding detection equipment has poor versatility, low precision and is difficult to implement.

[0005] The energy storage converter DC side insulation resistance detection circuit provided by the present invention comprises a first switch resistor, a first matching switch, a first fixed resistor, a second switch resistor, a second matching switch, a second fixed resistor, and a third fixed resistor, wherein the first switch resistor and the first fixed resistor are connected in series between a positive bus and a ground line, the first matching switch is connected at both ends of the first switch resistor, the third fixed resistor is connected in parallel with the first switch resistor and the first fixed resistor, and is connected between the positive bus and the ground line; the second switch resistor and the second fixed resistor are connected between a negative bus and a ground line, and the second matching switch is connected at both ends of the second switch resistor.

[0006] The present invention also provides a detection method for a DC side insulation resistance detection circuit of an energy storage converter, the method comprising:

[0007] Control the first matching switch and the second matching switch to be disconnected, measure the current negative bus voltage and the total bus voltage, obtain a first negative bus voltage and a first total bus voltage, and obtain a first positive bus voltage by subtracting the first negative bus voltage from the first total bus voltage;

[0008] Controlling the first matching switch to close and the second matching switch to open, measuring the current negative bus voltage and the total bus voltage, obtaining a second negative bus voltage and a second total bus voltage, subtracting the second negative bus voltage from the second total bus voltage to obtain a second positive bus voltage, and determining the positive bus insulation impedance and the negative bus insulation impedance according to the first positive and negative bus voltages and the second positive and negative bus voltages;

[0009] If the second negative bus voltage is less than the ideal preset value, the first matching switch and the second matching switch are controlled to be closed, and the current negative bus voltage and the total bus voltage are measured to obtain the third negative bus voltage and the third total bus voltage, and the third positive bus voltage is subtracted from the third total bus voltage to obtain the third positive bus voltage; the positive bus insulation impedance and the negative bus insulation impedance are determined according to the first positive and negative bus voltages and the third positive and negative bus voltages.

[0010] Specifically, the calculation formula of the impedance is:

[0011]

[0012] Among them, U 1P is the first positive bus voltage, U 1n is the first negative bus voltage, U 2P is the second positive bus voltage, U 2n is the second negative bus voltage, U 3P is the third positive bus voltage, U 3n is the third negative bus voltage, R x is the insulation resistance of the positive busbar, R y is the negative bus insulation impedance, R1p is the value of the first switch resistor R1p, R1 is the value of the first fixed resistor R1, R2p is the value of the second switch resistor R2p, R2 is the value of the second fixed resistor R2, and R3 is the value of the third fixed resistor R3.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] Sampling the positive bus voltage and negative bus voltage to determine the insulation resistance effectively prevents the problem of insufficient sampling due to low voltage, and effectively improves the accuracy of insulation impedance detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the circuit diagram of the DC side insulation resistance detection circuit of the energy storage converter.

[0016] Figure 2 The present invention is a flow chart of a detection method for a DC side insulation resistance detection circuit of an energy storage converter. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example

[0019] See also Figure 1-2 The present embodiment provides a DC side insulation resistance detection circuit of an energy storage converter, comprising a first switch resistor R1p, a first matching switch JOC2, a first fixed resistor R1, a second switch resistor R2p, a second matching switch JOC1, a second fixed resistor R2, and a third fixed resistor R3, wherein the first switch resistor R1p and the first fixed resistor R1 are connected in series between the positive bus Bat+ and the grounding line PE, the first matching switch JOC2 is connected at both ends of the first switch resistor R1p, the third fixed resistor R3 is connected in parallel with the first switch resistor R1p and the first fixed resistor R1, and is connected between the positive bus Bat+ and the grounding line PE; the second switch resistor R2p and the second fixed resistor R2 are connected between the negative bus Bat- and the grounding line PE, and the second matching switch JOC1 is connected at both ends of the second switch resistor R2p.

[0020] The present invention also provides a detection method for a DC side insulation resistance detection circuit of an energy storage converter, the method comprising:

[0021] Control the first matching switch JOC2 and the second matching switch JOC1 to be disconnected, measure the current negative bus voltage and the total bus voltage, obtain the first negative bus voltage and the first total bus voltage, and obtain the first positive bus voltage by subtracting the first negative bus voltage from the first total bus voltage;

[0022] Control the first matching switch JOC2 to close and the second matching switch JOC1 to open, measure the current negative bus voltage and the total bus voltage, obtain the second negative bus voltage and the second total bus voltage, subtract the second negative bus voltage from the second total bus voltage to obtain the second positive bus voltage, and determine the positive bus insulation impedance and the negative bus insulation impedance according to the first positive and negative bus voltages and the second positive and negative bus voltages;

[0023] If the second negative bus voltage is less than the ideal preset value, the first matching switch JOC2 is controlled to be closed and the second matching switch JOC1 is controlled to be closed, and the current negative bus voltage and the total bus voltage are measured to obtain the third negative bus voltage and the third total bus voltage, and the third positive bus voltage is subtracted from the third total bus voltage to obtain the third positive bus voltage; the positive bus insulation impedance and the negative bus insulation impedance are determined according to the first positive and negative bus voltages and the third positive and negative bus voltages.

[0024] Specifically, the calculation formula of the impedance is:

[0025]

[0026] Among them, U 1P is the first positive bus voltage, U 1n is the first negative bus voltage, U 2P is the second positive bus voltage, U 2n is the second negative bus voltage, U 3P is the third positive bus voltage, U 3n is the third negative bus voltage, R x is the insulation resistance of the positive busbar, R y is the negative bus insulation impedance, R1p is the value of the first switch resistor R1p, R1 is the value of the first fixed resistor R1, R2p is the value of the second switch resistor R2p, R2 is the value of the second fixed resistor R2, and R3 is the value of the third fixed resistor R3.

[0027] When sampling the second negative bus voltage, the first matching switch JOC2 is closed and the second matching switch JOC1 is opened. The equivalent resistance of the positive bus Bat+ to ground is the first switch resistance R1p connected in series with the first fixed resistance R1 and connected in parallel with the positive bus insulation resistance Rx and the third fixed resistance R3; the equivalent resistance of the negative bus Bat- to ground is the negative bus insulation resistance R y When sampling the third negative bus voltage, the first matching switch JOC2 is disconnected and the second matching switch JOC1 is closed. The equivalent resistance of the positive bus Bat+ to ground is the positive bus insulation impedance Rx connected in parallel with the first fixed resistor R1 and the third fixed resistor R3. The equivalent resistance of the negative bus Bat- to ground is the second switch resistor R2p connected in series with the second fixed resistor R2 and the negative bus insulation impedance R y Thus, if the resistance of each resistor is known, Rx and Ry are unknown quantities, and the remaining parameters are known quantities, the values ​​of Rx and Ry can be obtained.

[0028] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A DC side insulation resistance detection circuit for an energy storage converter. Features: It includes a first switch resistor, a first matching switch, a first fixed resistor, a second switch resistor, a second matching switch, a second fixed resistor, and a third fixed resistor. The first switch resistor and the first fixed resistor are connected in series between the positive bus and the ground line. The first matching switch is connected to both ends of the first switch resistor. The third fixed resistor is connected in parallel with the first switch resistor and the first fixed resistor, and is connected between the positive bus and the ground line. The second switch resistor and the second fixed resistor are connected between the negative bus and the ground line, and the second matching switch is connected to both ends of the second switch resistor.

2. A detection method for a DC side insulation resistance detection circuit of an energy storage converter, Features: Control the first matching switch and the second matching switch to be disconnected, measure the current negative bus voltage and the total bus voltage, obtain a first negative bus voltage and a first total bus voltage, and obtain a first positive bus voltage by subtracting the first negative bus voltage from the first total bus voltage; Controlling the first matching switch to close and the second matching switch to open, measuring the current negative bus voltage and the total bus voltage, obtaining a second negative bus voltage and a second total bus voltage, subtracting the second negative bus voltage from the second total bus voltage to obtain a second positive bus voltage, and determining the positive bus insulation impedance and the negative bus insulation impedance according to the first positive and negative bus voltages and the second positive and negative bus voltages; If the second negative bus voltage is less than the ideal preset value, the first matching switch and the second matching switch are controlled to be closed, and the current negative bus voltage and the total bus voltage are measured to obtain the third negative bus voltage and the third total bus voltage, and the third positive bus voltage is subtracted from the third total bus voltage to obtain the third positive bus voltage; the positive bus insulation impedance and the negative bus insulation impedance are determined according to the first positive and negative bus voltages and the third positive and negative bus voltages.

3. The detection method of the DC side insulation resistance detection circuit of the energy storage converter according to claim 2, Features: The impedance is calculated as: Among them, U 1P is the first positive bus voltage, U 1n is the first negative bus voltage, U 2P is the second positive bus voltage, U 2n is the second negative bus voltage, U 3P is the third positive bus voltage, U 3n is the third negative bus voltage, R x is the insulation resistance of the positive busbar, R y is the negative bus insulation impedance, R1p is the value of the first switch resistor R1p, R1 is the value of the first fixed resistor R1, R2p is the value of the second switch resistor R2p, R2 is the value of the second fixed resistor R2, and R3 is the value of the third fixed resistor R3.

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