DC circuit breaker active protection system

Abstract

The present invention provides a DC circuit breaker active protection system, comprising: a plurality of DC circuit breaker protection devices and a switch separation control device; each DC circuit breaker protection device comprises: a current transformer, a switch state acquisition device and a switch separation controller respectively connected to the current transformer and the switch state acquisition device; the switch separation control device is connected to each switch separation controller. The present invention can simplify the protection link, save the separation time and reduce the risk of failure.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breakers, and in particular to an active protection system for a direct current circuit breaker. Background Art

[0002] Compared with AC systems, DC fault current lacks a natural zero point. To achieve reliable interruption, it is necessary to artificially create a current zero point, and at the same time, it is necessary to absorb the huge energy stored in the inductive components of the DC system. Therefore, the design of DC circuit breakers is much more difficult than that of AC circuit breakers. Current high-voltage DC circuit breakers generally have three branches, including a current-passing branch, a transfer branch, and an energy-consuming branch.

[0003] Existing DC circuit breaker protection devices have many protection process links, high failure risk, and delayed breaking time of DC circuit breakers. The short-circuit current in the DC system rises very quickly, and the delay in breaking time may cause permanent damage to the equipment. Summary of the invention

[0004] The main purpose of the embodiments of the present invention is to provide an active protection system for a DC circuit breaker, so as to simplify the protection link, save the breaking time and reduce the risk of failure.

[0005] In order to achieve the above object, an embodiment of the present invention provides a DC circuit breaker active protection system, including:

[0006] Multiple DC circuit breaker protection devices and switch opening and closing control devices;

[0007] Each DC circuit breaker protection device includes: a current transformer, a switch state acquisition device, and a switch separation controller connected to the current transformer and the switch state acquisition device respectively; the switch separation control device is connected to each switch separation controller;

[0008] The current transformer is used to: collect the total current of the DC circuit breaker and output the total current to the switch opening and closing controller;

[0009] The switch state acquisition device is used to: acquire the opening and closing state of each switch in the DC circuit breaker, and output the switch state to the switch opening and closing controller according to the opening and closing state of each switch;

[0010] The switch opening and closing controller is used to: output a switch opening and closing signal to the switch opening and closing control device according to the total current and the switch state;

[0011] The switch opening and closing control device is used to: receive switch opening and closing signals from multiple switch opening and closing controllers; when the number of received switch opening and closing signals of the same type exceeds a preset value, send the switch opening and closing signal of this type to the DC circuit breaker.

[0012] The DC circuit breaker active protection system of the embodiment of the present invention includes multiple DC circuit breaker protection devices and switch separation and combination control devices; each DC circuit breaker protection device includes: a current transformer, a switch state acquisition device and a switch separation and combination controller respectively connected to the current transformer and the switch state acquisition device; the switch separation and combination control device is connected to each switch separation and combination controller, which can simplify the protection link, save the separation time and reduce the risk of failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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 description of the embodiments 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.

[0014] Figure 1 is a schematic diagram of a DC circuit breaker active protection system in a first embodiment of the present invention;

[0015] Figure 2 is a schematic diagram of a switch of a DC circuit breaker in a first switching state according to an embodiment of the present invention;

[0016] Figure 3 is a schematic diagram of a switch of a DC circuit breaker in a second switch state according to an embodiment of the present invention;

[0017] Figure 4 is a schematic diagram of a switch of a DC circuit breaker in a third switch state according to an embodiment of the present invention;

[0018] Figure 5 is a schematic diagram of a DC circuit breaker active protection system in a second embodiment of the present invention;

[0019] Figure 6 Schematic diagram of a DC circuit breaker active protection system in a third embodiment of the present invention. DETAILED DESCRIPTION

[0020] 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.

[0021] Those skilled in the art will appreciate that the embodiments of the present invention may be implemented as a system, device, apparatus, method or computer program product. Therefore, the present disclosure may be specifically implemented in the following forms, namely: complete hardware, complete software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0022] In view of the problems of the prior art such as multiple protection process links, high fault risk, and delayed disconnection time of DC circuit breakers, the embodiment of the present invention provides a DC circuit breaker protection system to simplify the protection links, save disconnection time, and reduce fault risk. The present invention is described in detail below with reference to the accompanying drawings.

[0023] Figure 1 Schematic diagram of the active protection system of a DC circuit breaker in the first embodiment of the present invention. Figure 1 As shown, the DC circuit breaker active protection system includes:

[0024] Multiple DC circuit breaker protection devices and switch opening and closing control devices;

[0025] Each DC circuit breaker protection device includes: a current transformer, a switch state acquisition device, and a switch separation controller connected to the current transformer and the switch state acquisition device respectively; the switch separation control device is connected to each switch separation controller;

[0026] The current transformer is used to: collect the total current of the DC circuit breaker and output the total current to the switch opening and closing controller;

[0027] The switch state acquisition device is used to: acquire the opening and closing state of each switch in the DC circuit breaker, and output the switch state to the switch opening and closing controller according to the opening and closing state of each switch;

[0028] The switch opening and closing controller is used to: output a switch opening and closing signal to the switch opening and closing control device according to the total current and the switch state;

[0029] The switch state includes a first switch state, a second switch state and a third switch state. The switch opening and closing signal includes a first switch opening and closing signal, a second switch opening and closing signal, a third switch opening and closing signal and a fourth switch opening and closing signal.

[0030] The switch opening and closing control device is used to: receive switch opening and closing signals from multiple switch opening and closing controllers; when the number of received switch opening and closing signals of the same type exceeds a preset value, send the switch opening and closing signal of this type to the DC circuit breaker.

[0031] Figure 2 Schematic diagram of a switch of a DC circuit breaker in a first switching state according to an embodiment of the present invention. Figure 3 Schematic diagram of a switch of a DC circuit breaker in a second switching state according to an embodiment of the present invention. Figure 4 FIG. 1 is a schematic diagram of a DC circuit breaker switch in a third switch state according to an embodiment of the present invention. Figure 2-Figure 4 As shown, the switch state acquisition device is specifically used for:

[0032] When the switch located in the flow branch is closed and the switch located in the transfer branch is opened, the first switch state is output to the switch opening and closing controller; at this time, the flow branch is turned on and the transfer branch is turned off.

[0033] When the switch located in the flow branch is opened and the switch located in the transfer branch is closed, the second switch state is output to the switch opening and closing controller; at this time, the flow branch is opened and the transfer branch is turned on.

[0034] When the switch located in the flow branch is disconnected and the switch located in the transfer branch is disconnected, the third switch state is output to the switch opening and closing controller. At this time, the flow branch is disconnected, the transfer branch is disconnected, the lightning arrester located in the energy consumption branch is broken down by the current, and the energy consumption branch is turned on.

[0035] In one embodiment, the switch opening and closing controller is specifically used for:

[0036] When the total current is greater than the overcurrent pre-transfer threshold and less than the overcurrent trip threshold and the switch state is the first switch state, a first switch opening and closing signal is sent to the switch opening and closing control device to switch the first switch state to the second switch state.

[0037] When the total current is greater than or equal to the overcurrent tripping threshold and the switch state is the second switch state, a second switch opening and closing signal is sent to the switch opening and closing control device to switch the second switch state to the third switch state.

[0038] When the total current is greater than the overcurrent pre-transfer threshold and less than the overcurrent trip threshold and the switch state is the third switch state, a third switch opening and closing signal is sent to the switch opening and closing control device to switch the third switch state to the second switch state;

[0039] When the total current is less than or equal to the overcurrent pre-transfer threshold and the switch state is in the second state, a fourth switch opening and closing signal is sent to the switch opening and closing control device to switch the second switch state to the first switch state.

[0040] The first switch opening and closing signal includes a flow branch switch opening signal and a transfer branch switch closing signal;

[0041] When the DC circuit breaker receives a signal to disconnect the on-current branch switch, the DC circuit breaker first disconnects the multiple power electronic switches located in the on-current branch according to the signal to disconnect the on-current branch switch, and then disconnects the multiple mechanical switches located in the on-current branch. At this time, the on-current branch is disconnected; when the DC circuit breaker receives a signal to close the transfer branch switch, the DC circuit breaker closes the multiple power electronic switches located in the transfer branch according to the signal to close the transfer branch switch. At this time, the transfer branch is turned on.

[0042] The second switch opening and closing signal is a transfer branch switch disconnection signal;

[0043] When the DC circuit breaker receives a transfer branch switch disconnect signal, the DC circuit breaker disconnects multiple power electronic switches located in the transfer branch according to the transfer branch switch disconnect signal. At this time, the transfer branch is disconnected, the lightning arrester located in the energy consumption branch is broken down by the current, and the energy consumption branch is turned on.

[0044] The third switch opening and closing signal is a transfer branch switch closing signal;

[0045] When the DC circuit breaker receives a transfer branch switch closing signal, the DC circuit breaker closes multiple power electronic switches located in the transfer branch according to the transfer branch switch closing signal. At this time, the transfer branch is turned on, the current does not break through the lightning arrester located in the energy consumption branch, and the energy consumption branch is disconnected.

[0046] The fourth switch opening and closing signal includes a flow branch switch closing signal and a transfer branch switch opening signal.

[0047] When the DC circuit breaker receives a transfer branch switch disconnect signal, the DC circuit breaker disconnects multiple power electronic switches located in the transfer branch according to the transfer branch switch disconnect signal, and the transfer branch is disconnected. When the DC circuit breaker receives a through-flow branch switch closing signal, the DC circuit breaker first closes multiple power electronic switches located in the through-flow branch according to the through-flow branch switch closing signal, and then closes multiple mechanical switches located in the through-flow branch, and the through-flow branch is turned on.

[0048] In one embodiment, when the total current is greater than the maximum breaking current of the active protection system of the DC circuit breaker, the switch separation controller sends a locking signal to the switch separation control device. When the switch separation control device receives a number of locking signals exceeding a preset value, it sends a locking signal to the DC circuit breaker. The DC circuit breaker maintains the current branch state according to the locking signal and does not perform any closing or opening operation on the switch.

[0049] Figure 5 Schematic diagram of the active protection system of a DC circuit breaker in the second embodiment of the present invention. Figure 5 As shown, the DC circuit breaker active protection system also includes: a redundant switch status acquisition device;

[0050] The redundant switch state acquisition device is connected to the switch separation controller, and is used to obtain the number of redundant switches and output the number of redundant switches to the switch separation controller;

[0051] The switch separation controller is used to adjust the overcurrent tripping threshold according to the number of redundant switches. When the number of redundant switches decreases, it indicates that the DC circuit breaker's ability to withstand overcurrent and risk decreases, and the overcurrent tripping threshold is reduced at this time.

[0052] Among them, the mechanical switch has multiple ports, and generally has one or two redundant switches; the power electronic switches in the current-carrying branch and the transfer branch generally adopt a structure in which multiple modules are connected in series and then in parallel. There are several redundant switches in each of the multiple modules in series, and there are one or two strings of redundant switches in the entire branch. The number of redundant switches represents the health of the DC circuit breaker and its ability to switch current.

[0053] Figure 6 Schematic diagram of the active protection system of a DC circuit breaker in the third embodiment of the present invention. Figure 6 As shown, the switch opening and closing control device is also connected to each switch state acquisition device;

[0054] The switch state acquisition device is also used to: output the switch state to the switch opening and closing control device according to the opening and closing state of each switch;

[0055] The switch opening and closing control device is used to: receive a trip signal from an external system and a switch status from multiple switch status acquisition devices; when the number of switch statuses of the same type received exceeds a preset value, output a trip switch opening and closing signal to the DC circuit breaker according to the switch status and the trip signal.

[0056] In one embodiment, when the switch state is the first switch state, a first trip switch opening and closing signal is output to the DC circuit breaker; when the switch state is the second switch state, a second trip switch opening and closing signal is output to the DC circuit breaker.

[0057] Among them, the first trip switch opening and closing signal includes a flow branch switch disconnection signal and a transfer branch switch disconnection signal; the second trip switch opening and closing signal is a transfer branch switch disconnection signal.

[0058] The specific process of one embodiment of the present invention is as follows:

[0059] 1. The switch status acquisition device outputs the switch status to the switch opening and closing control device according to the opening and closing status of each switch.

[0060] 2. The switch opening and closing control device receives the tripping signal from the external system and the switch status from multiple switch status acquisition devices; when the number of the same type of switch status received exceeds a preset value, the tripping switch opening and closing signal is output to the DC circuit breaker according to the switch status and the tripping signal. For example, when the number of the first tripping switch opening and closing signals received exceeds a preset value, the first tripping switch opening and closing signal is sent to the DC circuit breaker.

[0061] The specific process of another embodiment of the present invention is as follows:

[0062] 1. The redundant switch status acquisition device obtains the number of redundant switches and outputs the number of redundant switches to the switch separation controller.

[0063] 2. The switch opening and closing controller adjusts the overcurrent tripping threshold according to the number of redundant switches.

[0064] 3. The current transformer collects the total current of the DC circuit breaker and outputs the total current to the switch controller.

[0065] 4. The switch status acquisition device acquires the opening and closing status of each switch in the DC circuit breaker, and outputs the switch status to the switch opening and closing controller according to the opening and closing status of each switch.

[0066] 5. The switch opening and closing controller outputs the switch opening and closing signal to the switch opening and closing control device according to the total current and the switch status.

[0067] 6. The switch opening and closing control device receives switch opening and closing signals from multiple switch opening and closing controllers; when the number of received switch opening and closing signals of the same type exceeds a preset value, the switch opening and closing signal of the same type is sent to the DC circuit breaker. For example, when the number of received first switch opening and closing signals exceeds a preset value, the first switch opening and closing signal is sent to the DC circuit breaker.

[0068] In summary, the DC circuit breaker active protection system of the embodiment of the present invention includes multiple DC circuit breaker protection devices and switch separation and combination control devices; each DC circuit breaker protection device includes: a current transformer, a switch state acquisition device and a switch separation and combination controller respectively connected to the current transformer and the switch state acquisition device; the switch separation and combination control device is connected to each switch separation and combination controller, which can simplify the protection link, save the separation time, and reduce the risk of failure.

[0069] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A DC circuit breaker active protection system, characterized in that: include: Multiple DC circuit breaker protection devices and switch opening and closing control devices; Each DC circuit breaker protection device comprises: a current transformer, a switch state acquisition device and a switch separation controller connected to the current transformer and the switch state acquisition device respectively; the switch separation control device is connected to each switch separation controller; The current transformer is used to: collect the total current of the DC circuit breaker and output the total current to the switch opening and closing controller; The switch state acquisition device is used to: acquire the opening and closing state of each switch in the DC circuit breaker, and output the switch state to the switch opening and closing controller according to the opening and closing state of each switch; The switch opening and closing controller is used to: output a switch opening and closing signal to the switch opening and closing control device according to the total current and the switch state; The switch opening and closing control device is used to: receive switch opening and closing signals from the plurality of switch opening and closing controllers; when the number of received switch opening and closing signals of the same type exceeds a preset value, send the switch opening and closing signal of the same type to the DC circuit breaker; The switch state includes a first switch state, a second switch state and a third switch state; The switch opening and closing signals include a first switch opening and closing signal, a second switch opening and closing signal, a third switch opening and closing signal and a fourth switch opening and closing signal; The switch opening and closing controller is specifically used for: When the total current is greater than the overcurrent pre-transfer threshold and less than the overcurrent trip threshold and the switch state is the first switch state, sending a first switch opening and closing signal to the switch opening and closing control device; When the total current is greater than or equal to the overcurrent tripping threshold and the switch state is the second switch state, sending a second switch opening and closing signal to the switch opening and closing control device; When the total current is greater than the overcurrent pre-transfer threshold and less than the overcurrent trip threshold and the switch state is the third switch state, sending a third switch opening and closing signal to the switch opening and closing control device; When the total current is less than or equal to the overcurrent pre-transfer threshold and the switch state is in the second state, sending a fourth switch opening and closing signal to the switch opening and closing control device; The DC circuit breaker active protection system also includes a DC circuit breaker protection device; The DC circuit breaker protection device further comprises: a redundant switch status acquisition device; The redundant switch state acquisition device is connected to the switch separation controller, and is used to obtain the number of redundant switches and output the number of redundant switches to the switch separation controller; The switch on / off controller is used to: adjust the overcurrent trip threshold according to the number of the redundant switches; The switch opening and closing control device is also connected to each switch status acquisition device; The switch state acquisition device is also used to: output the switch state to the switch opening and closing control device according to the opening and closing state of each switch; The switch opening and closing control device is used to: receive a trip signal from an external system and a switch state from the multiple switch state acquisition devices; when the number of switch states of the same type received exceeds the preset value, output a trip switch opening and closing signal to the DC circuit breaker according to the switch state and the trip signal.

2. The DC circuit breaker active protection system according to claim 1, characterized in that: The switch state acquisition device is specifically used for: When the switch located in the flow branch is closed and the switch located in the transfer branch is opened, outputting a first switch state to the switch opening and closing controller; When the switch located in the flow branch is opened and the switch located in the transfer branch is closed, outputting a second switch state to the switch opening and closing controller; When the switch located in the flow branch is opened and the switch located in the transfer branch is opened, a third switch state is output to the switch opening and closing controller.

3. The DC circuit breaker active protection system according to claim 1, characterized in that: The first switch opening and closing signal includes a flow branch switch opening signal and a transfer branch switch closing signal; The second switch opening and closing signal is a transfer branch switch disconnection signal; The third switch opening and closing signal is a transfer branch switch closing signal; The fourth switch opening and closing signal includes a flow branch switch closing signal and a transfer branch switch opening signal.

4. The DC circuit breaker active protection system according to claim 1, characterized in that: When the switch state is the first switch state, outputting a first trip switch opening and closing signal to the DC circuit breaker; When the switch state is the second switch state, a second trip switch opening and closing signal is output to the DC circuit breaker.

5. The DC circuit breaker active protection system according to claim 4, characterized in that: The first trip switch opening and closing signal includes a flow branch switch disconnection signal and a transfer branch switch disconnection signal; The second trip switch opening and closing signal is a transfer branch switch disconnection signal.

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