System for protecting power electronic equipment in low-voltage direct-current micro-grid

Abstract

The invention discloses a system for protecting power electronic equipment in a low-voltage direct-current micro-grid, relates to the field of micro-grids, and aims at solving the problem that the speed of cutting off and isolating a fault position is low due to the fact that an existing control mode is complex. And the controller is used for collecting and processing the current output by the DC / DC converter, performing difference operation on the processed current and a preset current, and driving IGBT switch tubes Q1-Q2 of the DC / DC converter to realize locking according to an operation result. The invention is used for protecting the power electronic equipment.

Description

Technical Field

[0001] The invention relates to the field of microgrids and belongs to a switch tube cutting mode. Background Art

[0002] For low-voltage DC microgrids, the bus voltage is mainly controlled by the boost DC / DC converter connected to the bus. Once a DC fault occurs, even if the pulse is blocked in time after the fault, the boost DC / DC converter will still provide short-circuit current through the diode. In this process, the anti-parallel diode will be severely impacted by the fault current and even damaged. Therefore, if effective measures are not taken when a DC bus fault occurs, it will cause great damage to power electronic equipment. Fault protection in DC microgrids is crucial.

[0003] In the prior art, a fault control module is added to realize the identification and rapid isolation of the fault location. However, the existing control method is complicated, resulting in a slow speed of cutting off and isolating the fault location. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing control method is complex, resulting in slow speed of cutting off and isolating the fault location, and a system for protecting power electronic equipment in a low-voltage DC microgrid is proposed.

[0005] A system for protecting power electronic equipment in a low-voltage DC microgrid, wherein the DC / DC converter includes IGBT switch tubes Q1-Q2, and the system includes a controller;

[0006] The controller is used to collect the current output by the DC / DC converter for processing, perform difference calculation on the processed current and the preset current, and the calculation result drives the IGBT switch tubes Q1-Q2 of the DC / DC converter to achieve locking.

[0007] Preferably, the current output by the DC / DC converter is collected and proportional-integrated.

[0008] Preferably, the proportional integral is expressed as:

[0009]

[0010] Where s is the coefficient of variation and T1 is the control parameter.

[0011] Preferably, the controller is implemented using a chip of model STM32F103VET6.

[0012] The beneficial effects of the present invention are:

[0013] When the current output by the collected DC / DC converter is high, the difference between the processed current and the preset current is high, so the IGBT switch tubes Q1-Q2 driving the DC / DC converter are locked. The control method of the present invention is simple and the control speed is fast.

[0014] In addition, the proportional-integral processing is equivalent to filtering, making the control of the switch tube more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the structural diagram of the low voltage DC microgrid system;

[0016] Figure 2 Schematic diagram of a system for protecting power electronic equipment in a low-voltage DC microgrid. 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] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0019] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0020] Example:

[0021] A system for protecting power electronic equipment in a low-voltage DC microgrid, wherein the DC / DC converter includes IGBT switch tubes Q1-Q2, and the system includes a controller;

[0022] The controller is used to collect the current output by the DC / DC converter for processing, perform difference calculation on the processed current and the preset current, and the calculation result drives the IGBT switch tubes Q1-Q2 of the DC / DC converter to achieve locking.

[0023] Specifically, when the current output by the collected DC / DC converter is high, the difference between the processed current and the preset current is high, and therefore, the IGBT switch tubes Q1-Q2 driving the DC / DC converter are locked.

[0024] The processing method is introduced below: the current output by the acquisition controller is processed by proportional integration.

[0025] Specifically, the proportional-integral processing is equivalent to filtering, thereby protecting the current.

[0026] The proportional integral formula is introduced below: The proportional integral is expressed as:

[0027]

[0028] Where s is the coefficient of variation and T1 is the control parameter.

[0029] Working principle:

[0030] 1) Normal operation stage: The collected current is less than the hardware overcurrent protection threshold (preset current I ref ), the overcurrent protection will not be triggered. At this time, the circuit is in normal power supply mode, and Q1 and Q2 are always on.

[0031] 2) Fault blocking stage: Under DC short circuit fault, the current rises to be greater than the preset current I ref The overcurrent protection is triggered, prompting the controller to lock the drive signal, Q1 and Q2 are turned off, limiting the rise of the short-circuit current, and the current begins to decrease under the action of the freewheeling diode.

[0032] 3) Voltage recovery stage: After the instantaneous fault disappears or the fault is removed by relay protection, the switch device automatically switches back to the normal on mode after being normally on for a period of time, preparing for the next protection triggering.

[0033] The controller model is introduced below: The controller is implemented using a chip model STM32F103VET6.

[0034] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A system for protecting power electronic equipment in a low voltage DC microgrid, wherein the DC / DC converter includes IGBT switch tubes Q1-Q2, and is characterized in that: The system includes a controller; The controller is used to collect the current output by the DC / DC converter for processing, perform difference calculation on the processed current and the preset current, and the calculation result drives the IGBT switch tubes Q1-Q2 of the DC / DC converter to achieve locking.

2. The system for protecting power electronic equipment in a low voltage DC microgrid according to claim 1, characterized in that: The current output by the DC / DC converter is collected and processed in proportional integration.

3. The system for protecting power electronic equipment in a low voltage DC microgrid according to claim 2, characterized in that: The proportional integral is expressed as: Where s is the coefficient of variation and T1 is the control parameter.

4. The system for protecting power electronic equipment in a low voltage DC microgrid according to claim 1, characterized in that: The controller is implemented using a chip called STM32F103VET6.

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