CN113809724B - Main branch electronic switch protection method and device for hybrid high-voltage direct-current breaker - Google Patents

Abstract

A method and device for protecting the main branch electronic switch of a hybrid high-voltage DC circuit breaker. The main branch electronic switch is composed of an m-level module series group, including k series group redundant modules. Each level series group is composed of n levels of parallel power The module consists of j parallel redundant modules; each parallel power module is connected in parallel with a bypass switch to isolate the faulty module and form a through-flow branch. This method determines whether there is a loss of series redundancy of power modules and a loss of parallel redundancy of power modules, and combines the current status of the circuit breaker to control the action of the circuit breaker to achieve overcurrent and overvoltage protection of the main branch electronic switch and improve The reliability of the operation of the circuit breaker itself.

Description

Main branch electronic switch protection method and device of hybrid high-voltage DC circuit breaker

Technical field

The invention belongs to the technical field of high-voltage DC circuit breakers, and specifically relates to a main branch electronic switch protection method and device of a hybrid high-voltage DC circuit breaker.

Background technique

The hybrid high-voltage DC circuit breaker inherits the excellent static characteristics of the mechanical DC circuit breaker and the fast breaking dynamic characteristics of the solid-state DC circuit breaker. It is considered to be the most likely type of high-voltage DC circuit breaker to be widely used in the future DC power grid.

The hybrid DC circuit breaker is composed of three parallel branches, including: main branch, transfer branch and energy consumption branch. The main branch is used to conduct the system load current, the transfer branch is used to break DC fault current and withstand transient breaking voltage; the energy-consuming branch is used to suppress the transient breaking overvoltage of the circuit breaker and absorb the system stored energy. The main branch is composed of a mechanical switch and an electronic switch connected in series. The main branch electronic switch can withstand high voltage through modules in series, and can withstand high current through modules in parallel.

If the failure of the main branch electronic switch power module causes the loss of series redundancy of the main branch electronic switch, the voltage withstand capability of the main branch electronic switch will be affected; if the failure of the power module body causes the loss of parallel redundancy of the main branch electronic switch, Affects the current withstand capability of the transfer branch.

Contents of the invention

The purpose of the present invention is to provide a hybrid high-voltage DC circuit breaker main branch electronic switch protection method and device, which combines the characteristics of the circuit breaker main branch electronic switch equipment and the circuit breaker opening and closing action principles, and can be used in different circuit breakers. In this state, overvoltage and overcurrent protection are realized when the main branch electronic switch body fails, which improves the safety of the operation of the circuit breaker body equipment.

In order to achieve the above object, the first aspect of the present invention provides a method for protecting the main branch electronic switch of a hybrid high-voltage DC circuit breaker. The main branch electronic switch is composed of m-level module series groups, including k series groups of redundant circuits. Redundant modules, each series group is composed of n-level parallel power modules, including j parallel redundant modules; each parallel power module is connected in parallel with a bypass switch to isolate the fault module and form a through-flow branch;

The protection method includes the following steps:

Real-time monitoring of the number p of faulty modules in the series group and the maximum number of faults q of the parallel power modules in the faulty modules of each stage of the series group;

According to the p and q values, determine whether there is a loss of series redundancy and/or a loss of parallel redundancy in the main branch electronic switch;

According to the status of the circuit breaker and the loss of series redundancy and/or loss of parallel redundancy, the operation of the circuit breaker is controlled according to predetermined conditions.

Further, the steps of real-time monitoring of the number p of faulty modules in the series group and the maximum number of faults q of the parallel power modules in the faulty modules of each stage of the series group include:

When any module in the series group fails, all n-level parallel power modules in the series group will be bypassed, forming an n-level parallel current branch. Since this level of series group does not have the ability to withstand voltage, the faulty module series group will The number is recorded as: p=p+1, that is, the current number of faults is the number of previous faults plus 1;

If the bypass switch of the first-level faulty module in the i-th level series group fails to operate and does not close, then the faulty module at this level cannot form a parallel current branch, then the number of faults in the parallel power modules in the faulty module in the series group It is recorded as: q _i =q _i +1, that is, the current number of faults is the number of previous faults plus 1;

Compare the number of faults of the parallel power modules in the fault modules of each stage of the series group, and obtain the maximum number of faults, recorded as q.

Further, the step of determining whether there is a loss of series redundancy and/or a loss of parallel redundancy in the main branch electronic switch according to the p and q values includes:

When p>k, it is determined that the series redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand the peak breaking voltage;

When q>j, it is determined that the parallel redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand fault current.

Further, the step of controlling the operation of the circuit breaker according to predetermined conditions according to the status of the circuit breaker and the loss of series redundancy and/or loss of parallel redundancy includes:

When the circuit breaker is closed:

The main branch electronic switch's series redundancy and parallel redundancy are lost. When receiving a breaking command from the upper-layer control and protection system, the circuit breaker reports a failure, and the upper-layer control and protection system performs backup failure protection actions;

When only the main branch electronic switch series redundancy is lost, the circuit breaker is prohibited from opening, and the circuit breaker reports a failure after receiving a breaking command from the upper layer control protection system;

When only the main branch electronic switch parallel redundancy is lost, the circuit breaker is forced to perform self-opening;

When there is no series redundancy loss or parallel redundancy loss in the main branch electronic switch, the circuit breaker will open according to the upper layer control protection system opening command.

Further, the step of controlling the operation of the circuit breaker according to predetermined conditions according to the status of the circuit breaker and the loss of series redundancy and/or loss of parallel redundancy includes:

When the circuit breaker is in position:

When the series redundancy and/or parallel redundancy of the main branch electronic switch is lost, the circuit breaker is prohibited from closing;

When there is no loss of series redundancy and no loss of parallel redundancy, the circuit breaker will be closed according to the closing command of the upper layer control protection system.

The second aspect of the present invention provides a hybrid high-voltage DC circuit breaker main branch electronic switch protection device. The main branch electronic switch is composed of m-level module series groups, including k series group redundant modules. Each level The series group consists of n-level parallel power modules, including j parallel redundant modules; each parallel power module is connected in parallel with a bypass switch to isolate the faulty module and form a through-flow branch;

The protection device also includes:

The fault number monitoring module is used for real-time monitoring of the number p of fault modules in the series group and the maximum number of faults q of the parallel power modules in the fault modules of each stage of the series group;

The redundancy loss judgment module determines whether there is a series redundancy loss and/or a parallel redundancy loss in the main branch electronic switch according to the p and q values;

The circuit breaker control module controls the operation of the circuit breaker according to predetermined conditions according to the status of the circuit breaker and the loss of series redundancy and/or loss of parallel redundancy.

Further, the fault number monitoring module performs the following steps:

When any module in the series group fails, all n-level parallel power modules in the series group will be bypassed, forming an n-level parallel current branch. Since this level of series group does not have the ability to withstand voltage, the faulty module series group will The number is recorded as: p=p+1, that is, the current number of faults is the number of previous faults plus 1;

If the bypass switch of the first-level faulty module in the i-th level series group fails to operate and does not close, then the faulty module at this level cannot form a parallel current branch, then the number of faults in the parallel power modules in the faulty module in the series group It is recorded as: q _i =q _i +1, that is, the current number of faults is the number of previous faults plus 1;

Compare the number of faults of the parallel power modules in the fault modules of each stage of the series group, and obtain the maximum number of faults, recorded as q.

Further, the redundancy loss judgment module performs the following steps:

When p>k, it is determined that the series redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand the peak breaking voltage;

When q>j, it is determined that the parallel redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand fault current.

Further, the circuit breaker control module performs the following steps:

When the circuit breaker is closed:

The main branch electronic switch's series redundancy and parallel redundancy are lost. When receiving a breaking command from the upper-layer control and protection system, the circuit breaker reports a failure, and the upper-layer control and protection system performs backup failure protection actions;

When only the main branch electronic switch series redundancy is lost, the circuit breaker is prohibited from opening, and the circuit breaker reports a failure after receiving a breaking command from the upper layer control protection system;

When only the main branch electronic switch parallel redundancy is lost, the circuit breaker is forced to perform self-opening;

When there is no series redundancy loss or parallel redundancy loss in the main branch electronic switch, the circuit breaker will open according to the upper layer control protection system opening command.

Further, the circuit breaker control module performs the following steps:

When the circuit breaker is in position:

When the series redundancy and/or parallel redundancy of the main branch electronic switch is lost, the circuit breaker is prohibited from closing;

When there is no loss of series redundancy and no loss of parallel redundancy, the circuit breaker will be closed according to the closing command of the upper layer control protection system.

To sum up, the present invention provides a method and device for protecting the main branch electronic switch of a hybrid high-voltage DC circuit breaker. The main branch electronic switch is composed of an m-level module series group and includes k series group redundant modules. Each series group is composed of n-level parallel power modules, including j parallel redundant modules; each parallel power module is connected in parallel with a bypass switch to isolate the fault module and form a through-flow branch. This method determines whether there is a loss of series redundancy of power modules and a loss of parallel redundancy of power modules, and combines the current status of the circuit breaker to control the action of the circuit breaker to achieve overcurrent and overvoltage protection of the main branch electronic switch, improving The reliability of the operation of the circuit breaker itself.

Description of the drawings

Figure 1 is a schematic diagram of the principle of a hybrid high-voltage DC circuit breaker according to an embodiment of the present invention;

Figure 2 is a schematic diagram of the principle of the main branch electronic switch of the hybrid high-voltage DC circuit breaker according to an embodiment of the present invention;

Figure 3 is a schematic structural diagram of the main branch electronic switch power module of a hybrid high-voltage DC circuit breaker according to an embodiment of the present invention;

Figure 4 is a schematic flow chart of the opening process of a hybrid high-voltage DC circuit breaker according to an embodiment of the present invention;

FIG. 5 is a schematic flowchart of a thermal electronic switch protection method for the main branch of a hybrid high-voltage DC circuit breaker according to an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. Furthermore, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily confusing the concepts of the present invention.

The invention relates to a hybrid high-voltage DC circuit breaker, as shown in Figure 1. The hybrid DC circuit breaker consists of three parallel branches: main branch 1, transfer branch 2 and energy consumption branch 3. The main branch is composed of a fast mechanical switch 4 and a main branch electronic switch S1 connected in series, which is used to conduct the system current; the transfer branch is composed of an electronic switch S2 composed of a large number of power modules SM2 connected in series, which is used to turn off various transient and steady-state works. current; the energy-consuming branch is composed of MOV, which is used to suppress the transient breaking voltage of the circuit breaker and absorb inductive components to store energy.

As shown in Figure 2, the main branch electronic switch is composed of m series groups, including k series group redundancy. Each series group is composed of n parallel power modules, including j parallel redundant current branches.

As shown in Figure 3, the main branch electronic switching power module consists of an IGBT bridge, arrester F and bypass switch K, referred to as IGBT bridge power module. The IGBT bridge is used for on-off control of the module to achieve bidirectional flow. Lightning arrester F is used for voltage equalization and overvoltage protection of the module. When a certain power module fails, the bypass switch K is closed to protect the electronic switch of the power module.

Further, the opening process of the hybrid DC circuit breaker is shown in Figure 4, the details are as follows:

Main branch conduction stage (t0-t1): At time t0, a line failure occurs in the system. The fault current flows through the main branch mechanical switch and the main branch electronic switch. At this stage, the main branch electronic switch can withstand the fault current and its terminal voltage is very small.

Current transfer stage (t1-t2): The circuit breaker receives the breaking command and blocks the main branch electronic switch. A commutation voltage is generated at both ends of the circuit breaker, forcing the main branch current to transfer to the transfer branch current. The main branch fault current gradually attenuation. Due to the stray inductance in the main branch electronic switch body, when the main branch electronic switch turns off the fault current, a peak voltage will be superimposed on the commutation voltage of the main electronic switch.

Fast mechanical switch opening stage (t2-t3): After the main branch current crosses zero, the fast mechanical switch begins to open until the mechanical switch fracture has a sufficient opening distance, and then the transfer branch is blocked. At this stage, the on-state voltage drop of the transfer branch of the circuit breaker is very small, and the voltage at the electronic switch terminal of the main branch is very small.

Energy-consuming branch MOV action stage (t3-t4): The transient voltage is established after the transfer branch is blocked. When the voltage exceeds the MOV action voltage, the current gradually transfers from the transfer branch to the energy-consuming branch MOV until the transfer branch The current crosses zero. After the mechanical switch is disconnected, the equivalent impedance is much greater than the equivalent impedance of the main branch electronic switch, so the mechanical switch is subject to transient voltage, and the voltage at the main branch electronic switch terminal can be approximately equal to 0V.

MOV current attenuation stage (t4-t5): After the fault current is transferred to the energy-consuming branch MOV, the current gradually decays to zero due to the transient voltage established by the circuit breaker, and the MOV absorbs the remaining energy of the system in the process.

When the circuit breaker is closed, the system current flows through the main branch electronic switch through n parallel branches. The number n of parallel branches in the main branch series group is determined by the maximum withstand current of the main branch electronic switch and the maximum current of a single module. capacity and redundancy of parallel power modules. The number m of series groups in the main branch is determined by the maximum voltage endured by both ends of the main branch electronic switch, the maximum voltage withstand of a single power module, and the number of series redundancy requirements.

Therefore, the first aspect of the present invention provides a method for protecting the main branch electronic switch of a hybrid high-voltage DC circuit breaker. The main branch electronic switch is composed of an m-level module series group and includes k series group redundant modules. Each series group is composed of n-level parallel power modules, including j parallel redundant modules; each parallel power module is connected in parallel with a bypass switch to isolate the faulty module and form a through-flow branch;

The protection method includes the following steps, as shown in Figure 5:

Step S100: Real-time monitoring of the number p of faulty modules in the series group and the maximum number of faults q of the parallel power modules in the faulty modules of each stage of the series group.

Specifically, it includes the following steps:

When any module in the series group fails, all n-level parallel power modules in the series group will be bypassed, forming an n-level parallel current branch. Since this level of series group does not have the ability to withstand voltage, the faulty module series group will The number is recorded as: p=p+1, that is, the current number of faults is the number of previous faults plus 1;

If the bypass switch of the first-level faulty module in the i-th level series group fails to operate and does not close, then the faulty module at this level cannot form a parallel current branch, then the number of faults in the parallel power modules in the faulty module in the series group It is recorded as: q _i =q _i +1, that is, the current number of faults is the number of previous faults plus 1;

Compare the number of faults of the parallel power modules in the fault modules of each stage of the series group, and obtain the maximum number of faults, recorded as q.

Step S200: Based on the p and q values, determine whether there is a loss of series redundancy and/or a loss of parallel redundancy in the main branch electronic switch.

Specifically, when p>k, it is determined that the series redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand the peak breaking voltage;

When q>j, it is determined that the parallel redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand fault current.

Step S300: Control the operation of the circuit breaker according to predetermined conditions according to the status of the circuit breaker and the loss of series redundancy and/or loss of parallel redundancy.

Specifically, when the circuit breaker is closed:

The main branch electronic switch loses its series redundancy and parallel redundancy. After receiving the opening command from the upper-layer control system, the circuit breaker reports a failure, and the upper-layer control protection system performs backup failure protection actions. Specifically, the series redundancy is lost and the parallel redundancy is lost. The main branch electronic switch does not have the ability to flow for a long time and cannot withstand the voltage stress during disconnection. Therefore, the circuit breaker reports a failure, and the upper-layer control protection system performs failure protection and cuts off the line current.

When only the main branch electronic switch's series redundancy is lost, the main branch electronic switch cannot withstand the breaking voltage stress, and the circuit breaker is prohibited from opening; after receiving a breaking command from the upper-layer control protection system, the circuit breaker reports a failure;

When the parallel redundancy of only the main branch electronic switch is lost, the main electronic switch does not have the ability to carry current for a long time, and the circuit breaker is forced to perform self-opening;

When there is no series redundancy loss or parallel redundancy loss in the main branch electronic switch, the circuit breaker will open according to the upper layer control protection system opening command.

In the open state of the circuit breaker:

When the series redundancy and/or parallel redundancy of the main branch electronic switch is lost, the circuit breaker is prohibited from closing. Specifically, only the series redundancy is lost. If the main branch electronics cannot withstand the voltage stress during breaking after the circuit breaker is closed, and does not have the breaking capability, the circuit breaker is prohibited from closing. Only the parallel redundancy is lost. After the circuit breaker is closed by the split position, the main branch electronic switch does not have the ability to carry current for a long time, and the circuit breaker is prohibited from closing.

When there is no loss of series redundancy and no loss of parallel redundancy, the circuit breaker will be closed according to the closing command of the upper layer control protection system.

The second aspect of the present invention provides a hybrid high-voltage DC circuit breaker main branch electronic switch protection device. The main branch electronic switch is composed of m-level module series groups, including k series group redundant modules. Each level The series group consists of n-level parallel power modules, including j parallel redundant modules; each parallel power module is connected in parallel with a bypass switch to isolate the faulty module and form a through-flow branch;

The protection device also includes:

The fault number monitoring module is used for real-time monitoring of the number p of fault modules in the series group and the maximum number of faults q of the parallel power modules in the fault modules of each stage of the series group;

The redundancy loss judgment module determines whether there is a series redundancy loss and/or a parallel redundancy loss in the main branch electronic switch according to the p and q values;

The circuit breaker control module controls the operation of the circuit breaker according to predetermined conditions according to the status of the circuit breaker and the loss of series redundancy and/or loss of parallel redundancy.

Further, the fault number monitoring module performs the following steps:

When any module in the series group fails, all n-level parallel power modules in the series group will be bypassed, forming an n-level parallel current branch. Since this level of series group does not have the ability to withstand voltage, the faulty module series group will The number is recorded as: p=p+1, that is, the current number of faults is the number of previous faults plus 1;

If the bypass switch of the first-level faulty module in the i-th level series group fails to operate and does not close, then the faulty module at this level cannot form a parallel current branch, then the number of faults in the parallel power modules in the faulty module in the series group It is recorded as: q _i =q _i +1, that is, the current number of faults is the number of previous faults plus 1;

Compare the number of faults of the parallel power modules in the fault modules of each stage of the series group, and obtain the maximum number of faults, recorded as q.

Further, the redundancy loss judgment module performs the following steps:

When p>k, it is determined that the series redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand the peak breaking voltage;

When q>j, it is determined that the parallel redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses its ability to withstand fault current.

Further, the circuit breaker control module performs the following steps:

When the circuit breaker is closed:

The main branch electronic switch's series redundancy and parallel redundancy are lost. When receiving a breaking command from the upper-layer control and protection system, the circuit breaker reports a failure, and the upper-layer control and protection system performs backup failure protection actions;

When only the main branch electronic switch series redundancy is lost, the circuit breaker is prohibited from opening, and the circuit breaker reports a failure after receiving a breaking command from the upper layer control protection system;

When only the main branch electronic switch parallel redundancy is lost, the circuit breaker is forced to perform self-opening;

When there is no series redundancy loss or parallel redundancy loss in the main branch electronic switch, the circuit breaker will open according to the upper layer control protection system opening command.

Further, the circuit breaker control module performs the following steps:

When the circuit breaker is in position:

When the series redundancy and/or parallel redundancy of the main branch electronic switch is lost, the circuit breaker is prohibited from closing;

When there is no loss of series redundancy and no loss of parallel redundancy, the circuit breaker will be closed according to the closing command of the upper layer control protection system.

To sum up, the present invention provides a method and device for protecting the main branch electronic switch of a hybrid high-voltage DC circuit breaker. The main branch electronic switch is composed of an m-level module series group and includes k series group redundant modules. Each series group is composed of n-level parallel power modules, including j parallel redundant modules; each parallel power module is connected in parallel with a bypass switch to isolate the fault module and form a through-flow branch. This method determines whether there is a loss of series redundancy of power modules and a loss of parallel redundancy of power modules, and combines the current status of the circuit breaker to control the action of the circuit breaker to achieve overcurrent and overvoltage protection of the main branch electronic switch, improving The reliability of the operation of the circuit breaker itself.

It should be understood that the above-described specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included in the protection scope of the present invention. Furthermore, it is intended that the appended claims of the present invention cover all changes and modifications that fall within the scope and boundaries of the appended claims, or equivalents of such scopes and boundaries.

Claims (10)

1. The main branch electronic switch protection method of the hybrid high-voltage direct-current breaker is characterized in that the main branch electronic switch is composed of m-level module serial groups and comprises k serial group redundancy modules, each level serial group is composed of n-level parallel power modules and comprises j parallel redundancy modules; each parallel power module is connected with 1 bypass switch in parallel and is used for isolating a fault module and forming a through-flow branch;

the protection method comprises the following steps:

the number p of the fault modules of the series group and the maximum value q of the fault numbers of the parallel power modules in each stage of the fault modules of the series group are monitored in real time;

judging whether the main branch electronic switch has serial redundancy loss and/or parallel redundancy loss according to the p and q values;

and controlling the circuit breaker to work according to a preset condition according to the state of the circuit breaker and the condition that the serial redundancy is lost and/or the parallel redundancy is lost.

2. The method for protecting a main branch electronic switch of a hybrid high voltage direct current breaker according to claim 1, wherein the step of monitoring the number p of fault modules in the series group and the maximum value q of the number of faults of the parallel power modules in each stage of fault modules in the series group in real time comprises:

when any module in the series group fails, all the n-level parallel power modules in the series group bypass to form n-level parallel communication flow branches, and the number of the series group of failure modules is recorded as follows because the series group of the n-level parallel power modules does not have voltage tolerance: p=p+1, i.e. the current number of faults is the previous number of faults plus 1;

if the bypass switch of the first-stage fault module is refused to be closed in the i-th-stage serial group fault module, the first-stage fault module cannot form and communicate with a flow branch, and the number of faults of the parallel power modules in the serial group fault module is recorded as follows: q _i ＝q _i +1, i.e. the current number of faults is the previous number of faults plus 1;

and comparing the number of faults of the parallel power modules in each stage of series fault modules to obtain the maximum value of the number of faults, and marking the maximum value as q.

3. The method according to claim 1 or 2, wherein the step of determining whether there is a loss of series redundancy and/or a loss of parallel redundancy in the main branch electronic switch according to the p and q values comprises:

when p is more than k, judging that the serial redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses the capacity of tolerating breaking peak voltage;

when q is more than j, judging that the parallel redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses the fault current tolerance capability.

4. A method of protecting a main branch electronic switch of a hybrid high voltage dc circuit breaker according to claim 3, wherein said step of controlling the operation of the circuit breaker according to predetermined conditions based on the state of the circuit breaker and the loss of the serial redundancy and/or the loss of the parallel redundancy comprises:

under the state of closing the circuit breaker:

when the main branch electronic switch is lost in series redundancy and in parallel redundancy, and a breaking command of an upper control protection system is received, reporting loss of the circuit breaker, and executing backup failure protection action by the upper control protection system;

when the serial redundancy of the main branch electronic switch is lost, the breaker prohibits breaking the gate, and receives a breaking command of the upper control protection system, and the breaker reports the failure;

when the parallel redundancy of the main branch electronic switch is lost, the breaker forcibly executes self-breaking;

when the main branch electronic switch has no serial redundancy loss and no parallel redundancy loss, the breaker executes switching-off according to a switching-off instruction of the upper control protection system.

5. The method of claim 4, wherein the step of controlling the operation of the circuit breaker according to a predetermined condition based on the state of the circuit breaker and the loss of the serial redundancy and/or the loss of the parallel redundancy comprises:

under the breaker split state:

when the serial redundancy of the main branch electronic switch is lost and/or the parallel redundancy is lost, the circuit breaker prohibits the combination;

when no serial redundancy is lost and no parallel redundancy is lost, the circuit breaker executes switching-on according to switching-on instructions of the upper control protection system.

6. The main branch electronic switch protection device of the hybrid high-voltage direct-current breaker is characterized by comprising m-level module serial groups, wherein each level serial group comprises k serial group redundancy modules, each level serial group comprises n-level parallel power modules and j parallel redundancy modules; each parallel power module is connected with 1 bypass switch in parallel and is used for isolating a fault module and forming a through-flow branch;

the protection device further includes:

the fault number monitoring module is used for monitoring the number p of the fault modules of the series group and the maximum value q of the fault numbers of the parallel power modules in each stage of the fault modules of the series group in real time;

the redundancy loss judging module judges whether the main branch electronic switch has serial redundancy loss and/or parallel redundancy loss according to the p and q values;

and the circuit breaker control module is used for controlling the circuit breaker to work according to a preset condition according to the state of the circuit breaker and the condition that the serial redundancy is lost and/or the parallel redundancy is lost.

7. The hybrid high voltage direct current breaker main branch electronic switch protection device of claim 6, wherein the fault count monitoring module performs the steps of:

when any module in the series group fails, all the n-level parallel power modules in the series group bypass to form n-level parallel communication flow branches, and the number of the series group of failure modules is recorded as follows because the series group of the n-level parallel power modules does not have voltage tolerance: p=p+1, i.e. the current number of faults is the previous number of faults plus 1;

if the bypass switch of the first-stage fault module is refused to be closed in the i-th-stage serial group fault module, the first-stage fault module cannot form and communicate with a flow branch, and the number of faults of the parallel power modules in the serial group fault module is recorded as follows: q _i ＝q _i +1, i.e. the current number of faults is the previous number of faults plus 1;

and comparing the number of faults of the parallel power modules in each stage of series fault modules to obtain the maximum value of the number of faults, and marking the maximum value as q.

8. The hybrid high voltage direct current breaker main branch electronic switch protection device of claim 6 or 7, wherein the redundancy loss judging module performs the steps of:

when p is more than k, judging that the serial redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses the capacity of tolerating breaking peak voltage;

when q is more than j, judging that the parallel redundancy of the main branch electronic switch is lost, and the main branch electronic switch loses the fault current tolerance capability.

9. The hybrid high voltage dc breaker main branch electronic switch protection device of claim 8, wherein the breaker control module performs the steps of:

under the state of closing the circuit breaker:

when the main branch electronic switch is lost in series redundancy and in parallel redundancy, and a breaking command of an upper control protection system is received, reporting loss of the circuit breaker, and executing backup failure protection action by the upper control protection system;

when the serial redundancy of the main branch electronic switch is lost, the breaker prohibits breaking the gate, and receives a breaking command of the upper control protection system, and the breaker reports the failure;

when the parallel redundancy of the main branch electronic switch is lost, the breaker forcibly executes self-breaking;

when the main branch electronic switch has no serial redundancy loss and no parallel redundancy loss, the breaker executes switching-off according to a switching-off instruction of the upper control protection system.

10. The hybrid high voltage direct current breaker main branch electronic switch protection device of claim 9 wherein said breaker control module performs the steps of:

under the breaker split state:

when the serial redundancy of the main branch electronic switch is lost and/or the parallel redundancy is lost, the circuit breaker prohibits the combination;

when no serial redundancy is lost and no parallel redundancy is lost, the circuit breaker executes switching-on according to switching-on instructions of the upper control protection system.