Multi-port dc circuit breaker element fault tripping method

Abstract

The application discloses a kind of multi-port DC circuit breaker element fault tripping methods.The operation reliability of multi-port DC circuit breaker is significantly decreased compared with general DC circuit breaker.The technical scheme used in the present application is: when closing main break branch, if the element fault in main break branch, all IGBTs are switched from off state to on state, if part of IGBTs fail to realize the action from off to on at this time, the bypass switch of the valve section where the faulty IGBTs are located is closed; when breaking through-flow branch, if the element fault in through-flow branch, all breaks are switched from closed state to open state; when breaking main break branch, if the element fault in main break branch, all IGBTs are switched from on state to off state.The present application minimizes the system loss caused by element fault by setting reasonable judgment and action logic, maximizes the action of multi-port DC circuit breaker, and effectively improves the operation reliability of multi-port DC circuit breaker.

Description

Technical Field

[0001] This invention belongs to the field of DC power grid technology, specifically a method for tripping a multi-port DC circuit breaker component in case of fault. Background Technology

[0002] In DC power grids, to effectively disconnect faulty lines and quickly restore the remaining healthy DC grid system, DC circuit breakers must be installed at both ends of each DC line. This results in a large number of DC circuit breakers being used, especially in complex ring network structures where the number of DC circuit breakers significantly exceeds the number of converters. Therefore, to reduce the cost of DC circuit breakers, multi-port DC circuit breakers can be used. By having multiple DC circuit breakers share the expensive disconnecting branch, the number of DC circuit breakers used can be reduced.

[0003] However, compared with ordinary DC circuit breakers, multi-port DC circuit breakers have a significantly increased number of components, resulting in a significant decrease in their operational reliability. At the same time, due to their integrated multi-port characteristics, when a fault occurs, it is easy to cause more severe consequences. Therefore, it is necessary to study the corresponding operating strategies of multi-port DC circuit breakers. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for tripping a multi-port DC circuit breaker due to component failure. When a component failure occurs, through reasonable judgment and action logic, the system loss caused by the component failure is minimized while maximizing the protection of the multi-port DC circuit breaker's operation, thereby improving the operational reliability of the multi-port DC circuit breaker.

[0005] Therefore, the present invention adopts the following technical solution: a multi-port DC circuit breaker element fault tripping method, which includes:

[0006] Step 1: Close the main circuit breaker branch. If a component in the main circuit breaker branch fails, switch all IGBTs from the off state to the on state. If some IGBTs fail to switch from off to on at this time, close the bypass switch of the valve section where the faulty IGBT is located. If the bypass switch fails to close, directly activate the DC circuit breaker failure trip protection. If all bypass switches close successfully, determine whether the number of normal valve sections meets the pressure requirements. If it does, proceed to Step 2. If it does not meet the requirements, directly activate the DC circuit breaker failure trip protection.

[0007] Step 2: Disconnect the current-carrying branch. If a component in the current-carrying branch fails, switch all the contacts from the closed state to the open state. If some contacts fail to open at this time, determine whether the number of normal contacts meets the pressure requirements. If it does, proceed to Step 3; otherwise, directly activate the multi-port DC circuit breaker for full disconnection protection.

[0008] Step 3: Disconnect the main branch circuit. If a component in the main branch circuit fails, switch all IGBTs from the ON state to the OFF state. If some IGBTs fail to switch from ON to OFF at this time, determine whether the number of normal IGBTs meets the voltage requirements. If it does, the multi-port DC circuit breaker will stop operating. If it does not meet the requirements, switch all IGBTs from the OFF state back to the ON state, and at the same time, activate the DC circuit breaker failure trip protection.

[0009] Furthermore, the multi-port DC circuit breaker has n ports, including n current-carrying branches, 2n diode branches, and 1 main disconnecting branch. Under normal operation, the current-carrying branches are in the conducting state, while the diode branches and the main disconnecting branch are in the disconnecting state.

[0010] Furthermore, the aforementioned flow path includes one branch consisting of m d A fast mechanical switch consisting of several disconnectors connected in series, wherein the diode branch is m e The main circuit is composed of a series of diodes, and the main circuit breaker branch is composed of a main circuit breaker switch and a surge arrester branch connected in parallel.

[0011] Furthermore, the main disconnect switch is composed of m i It consists of an IGBT and its anti-parallel diode connected in series.

[0012] Furthermore, the m mentioned d m e m i The rated voltage level U of the DC circuit breaker dc Break voltage level U d Diode voltage rating U e IGBT voltage level U i And the redundancy k of the flow branch break. d Diode redundancy k in diode branch e and the redundancy k of the main disconnect switch IGBT i Decide:

[0013]

[0014] The k d k e k i All values ​​are between 1.05 and 1.1.

[0015] Furthermore, in steps 1 and 3, after the DC circuit breaker failure trip protection is activated, all DC circuit breakers adjacent to the multi-port DC circuit breaker trip to achieve fault isolation.

[0016] Furthermore, in step 2, after the multi-port DC circuit breaker's full disconnection protection is activated, all current-carrying branches and current-breaking branches within the multi-port DC circuit breaker are directly disconnected.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention, without increasing the cost of primary equipment, minimizes system losses caused by component failures while maximizing the protection of multi-port DC circuit breakers by setting reasonable judgment and action logic, thereby effectively improving the operational reliability of multi-port DC circuit breakers and further promoting the development and application of DC circuit breakers in DC power grids. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the multi-port DC circuit breaker of the present invention;

[0021] Figure 2 This is a flowchart illustrating the fault tripping method for multi-port DC circuit breakers according to the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figure 1 As shown, the multi-port DC circuit breaker has n ports, internally including n current-carrying branches, 2n diode branches, and 1 main breaking branch. Under normal operation, the current-carrying branches are in the conducting state, while the diode branches and the main breaking branch are in the breaking state.

[0024] The flow path contains 1 branch consisting of m d A fast mechanical switch consisting of several disconnectors connected in series, with the diode branch being m. e The circuit consists of several diodes connected in series. The main circuit breaker branch consists of one main circuit breaker switch and one surge arrester branch connected in parallel. The main circuit breaker switch consists of m... iIt consists of an IGBT and its anti-parallel diode connected in series. d m e m i The rated voltage level U of the DC circuit breaker dc Break voltage level U d Diode voltage rating U e IGBT voltage level U i And the redundancy k of the flow branch break. d Diode redundancy k in diode branch e and the redundancy k of the main disconnect switch IGBT i Decision. k d k e and k i A value of 1.05 to 1.1 is acceptable.

[0025]

[0026] When a DC system fault occurs or the DC system operation mode needs to be switched, requiring the disconnection of a multi-port DC circuit breaker, the multi-port DC circuit breaker element fault tripping method adopts the following steps, such as... Figure 2 As shown.

[0027] Step 1: When closing the main branch circuit, if a component within the main branch circuit fails, the following strategy is adopted: The action requirement is to switch all IGBTs from the off state to the on state. If some IGBTs fail to achieve the action from off to on at this time, the bypass switch of the valve section where such a faulty IGBT is located is closed. If the bypass switch fails to close, the DC circuit breaker failure trip protection is directly activated, indicating that the DC circuit breaker has lost its breaking capacity, and the backup protection is activated to achieve fault isolation and other functions. If all bypass switches are successfully closed, it is determined whether the number of normal valve sections meets the pressure requirements. If it does, it indicates that the fault of some IGBTs does not affect the normal breaking of the DC circuit breaker, and the DC circuit breaker can continue to the next step, i.e., Step 2; if it does not meet the requirements, the DC circuit breaker failure trip protection is directly activated, and all DC circuit breakers adjacent to the multi-port DC circuit breaker trip to achieve fault isolation.

[0028] Step 2: When disconnecting the current-carrying branch, if a component in the current-carrying branch fails, the following strategy is selected: The action requirement is to switch all the contacts from the closed state to the open state. If some contacts fail to achieve the action from closed to open, it is determined whether the number of normal contacts meets the pressure-bearing requirements. If it does, it indicates that the failure of some contacts does not affect the normal disconnection of the DC circuit breaker, and the DC circuit breaker can continue to the next step, i.e., Step 3; if it does not meet the requirements, the multi-port DC circuit breaker is directly activated for full disconnection protection, and all current-carrying and current-breaking branches in the multi-port DC circuit breaker are directly disconnected.

[0029] Step 3: When disconnecting the main branch, if a component in the main branch fails, the following strategy is adopted: The action requirement is to switch all IGBTs from the on state to the off state. If some IGBTs fail to switch from on to off at this time, it is determined whether the number of normal IGBTs meets the voltage bearing requirement. If it does, it means that the failure of some IGBTs does not affect the normal disconnection of the DC circuit breaker, and the DC circuit breaker can stop operating. If it does not meet the requirement, the normal IGBTs will directly bear a voltage exceeding their own bearing capacity, which will lead to IGBT failure. Therefore, all IGBTs should be switched back from the off state to the on state immediately. At the same time, the DC circuit breaker failure trip protection should be activated, and all DC circuit breakers adjacent to the multi-port DC circuit breaker should trip to achieve fault isolation.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for tripping a multi-port DC circuit breaker component in case of fault, characterized in that, include: Step 1: Close the main disconnect branch. If the components in the main disconnect branch are faulty, switch all IGBTs from the off state to the on state. If some IGBTs fail to switch from off to on at this time, close the bypass switch of the valve section where such faulty IGBTs are located. If the bypass switch fails to close, the DC circuit breaker failure trip protection will be activated directly. If all bypass switches close successfully, it will be determined whether the number of normal valve sections meets the pressure requirements. If it does, proceed to step 2. If it does not meet the requirements, the DC circuit breaker failure trip protection will be activated directly. Step 2: Disconnect the current-carrying branch. If a component in the current-carrying branch fails, switch all the contacts from the closed state to the open state. If some contacts fail to open at this time, determine whether the number of normal contacts meets the pressure requirements. If it does, proceed to Step 3; otherwise, directly activate the multi-port DC circuit breaker for full disconnection protection. Step 3: Disconnect the main branch circuit. If a component in the main branch circuit fails, switch all IGBTs from the ON state to the OFF state. If some IGBTs fail to switch from ON to OFF at this time, determine whether the number of normal IGBTs meets the voltage requirements. If it does, the multi-port DC circuit breaker will stop operating. If it does not meet the requirements, switch all IGBTs from the OFF state back to the ON state, and at the same time, activate the DC circuit breaker failure trip protection.

2. The multi-port DC circuit breaker element fault tripping method according to claim 1, characterized in that, The multi-port DC circuit breaker has n ports and includes n current-carrying branches, 2n diode branches, and 1 main disconnecting branch. Under normal operation, the current-carrying branches are in the conducting state, while the diode branches and the main disconnecting branch are in the disconnecting state.

3. The multi-port DC circuit breaker element fault tripping method according to claim 2, characterized in that, The aforementioned flow path includes one branch consisting of m d A fast mechanical switch consisting of several disconnectors connected in series, wherein the diode branch is m e The main circuit is composed of a series of diodes, and the main circuit breaker branch is composed of a main circuit breaker switch and a surge arrester branch connected in parallel.

4. The multi-port DC circuit breaker element fault tripping method according to claim 3, characterized in that, The main disconnect switch is composed of m i It consists of an IGBT and its anti-parallel diode connected in series.

5. The multi-port DC circuit breaker element fault tripping method according to claim 4, characterized in that, The m d m e m i The rated voltage level U of the DC circuit breaker dc Break voltage level U d Diode voltage rating U e IGBT voltage level U i And the redundancy k of the flow branch break. d Diode redundancy k in diode branch e and the redundancy k of the main disconnect switch IGBT i Decide:

6. The multi-port DC circuit breaker element fault tripping method according to claim 5, characterized in that, The k d Take a value of 1.05 to 1.

1.

7. The multi-port DC circuit breaker element fault tripping method according to claim 5, characterized in that, The k e Take a value of 1.05 to 1.

1.

8. The multi-port DC circuit breaker element fault tripping method according to claim 5, characterized in that, The k i Take a value of 1.05 to 1.

1.

9. The multi-port DC circuit breaker element fault tripping method according to claim 1, characterized in that, In steps 1 and 3, after the DC circuit breaker failure trip protection is activated, all DC circuit breakers adjacent to the multi-port DC circuit breaker trip to achieve fault isolation.

10. The multi-port DC circuit breaker element fault tripping method according to claim 1, characterized in that, In step 2, after the multi-port DC circuit breaker's full trip protection is activated, all current-carrying branches and current-breaking branches within the multi-port DC circuit breaker are directly tripped.

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