WO2017063413A1

WO2017063413A1 - High-voltage direct-current breaker and control method therefor

Info

Publication number: WO2017063413A1
Application number: PCT/CN2016/089947
Authority: WO
Inventors: 石巍; 曹冬明; 方太勋; 谢晔源; 杨兵; 王宇; 吕玮; 刘彬
Original assignee: 南京南瑞继保电气有限公司; 南京南瑞继保工程技术有限公司
Priority date: 2015-10-14
Filing date: 2016-07-13
Publication date: 2017-04-20
Also published as: CN105262068A

Abstract

A high-voltage direct-current breaker and a control method therefor. The high-voltage direct-current breaker comprises an on-state current branch, a breaking current branch, and a bridge branch. The on-state current branch is formed by means of serial connection of a mechanical switch (S) and a current transfer module that comprises a fully-controlled device, and ensures low-on-state loss in a normal on state. The breaking current branch is formed by a nonlinear resistor (R1) and a fully-controlled device serial-connection valve block that are connected in parallel. The bridge branch comprises two bridge arms formed by four same commutation modules (D1, D2, D3, D4). Each of the commutation modules (D1, D2, D3, D4) is formed by an uncontrolled device serial-connection valve block and an inductor that are in serial connection. By introducing the bridge branch, the breaking current branch can break bidirectional line currents, the number of fully-controlled devices is reduced, and equipment costs are decreased.

Description

High-voltage DC circuit breaker and control method thereof

Technical field

The invention relates to a high voltage DC circuit breaker, and relates to a control method of a high voltage DC circuit breaker, belonging to the technical field of circuit breakers.

Background technique

With the development of multi-terminal DC transmission technology, high-voltage DC circuit breakers will become one of the key equipment to ensure the safe and stable operation of the system. Due to the high voltage level and low line impedance, the multi-terminal HVDC transmission system will soon affect the DC transmission network and the AC network, and the fault must be quickly removed. Therefore, the high-voltage DC circuit breaker needs to have a fast moving speed, can minimize the fault duration or suppress the fault current, and reduce the impact of the fault on the AC/DC transmission network.

At present, there are usually three ways of DC circuit breaker technology. 1) LC resonant DC circuit breaker: On the basis of the conventional AC mechanical circuit breaker, by adding an auxiliary circuit, the amplified oscillating current is superimposed on the DC current of the breaking arc gap. When the current crosses zero, the circuit is broken. The mechanical circuit breaker manufactured by this principle cannot meet the requirements of the multi-terminal flexible DC transmission system in terms of breaking time and breaking current capacity. 2) Solid-state DC circuit breaker can utilize high power to shut down Breaking the power electronic device, directly breaking the DC current, the solid-state circuit breaker manufactured by this principle can meet the requirements of the multi-terminal flexible DC system in time, but the loss in the normal conduction is too large, and the economy is poor; Hybrid DC circuit breaker: a combination of mechanical switch and power electronic device, the normal operation is through the mechanical switch, the mechanical switch is broken during the fault, and the generated arc voltage is used to transfer the current to the parallel connected power electronic device branch. Then, the current is broken by the power electronics. Based on this principle, the circuit breaker not only reduces the on-state loss, but also increases the breaking speed, but needs to break the line current in both directions, requiring a large number of full control devices to be connected in series. Reverse series connection, the number of full control devices and high price, resulting in high cost of DC circuit breaker equipment, affecting its wide application and promotion.

Summary of the invention

The object of the present invention is to overcome the deficiencies in the prior art and provide a high voltage DC circuit breaker, which can significantly reduce equipment cost and increase equipment scalability while ensuring a sufficiently fast breaking speed and low loss.

In order to achieve the above object, the technical solution adopted by the present invention is: a high voltage DC circuit breaker comprising an on-state current branch, a current commutation and breaking unit; the on-state current branch comprising a series connection: a mechanical switch S And a current transfer module including a fully controlled device;

The current commutation and breaking unit comprises: a bridge branch and a breaking current branch;

The bridge branch includes: two identical bridge arms in the same direction, the bridge arm is composed of two commutation modules connected in series in the same direction, and the commutation module is composed of an uncontrolled device series valve group and an inductor Connected in series; the connecting node of the two commutation modules of the two bridge arms serves as two terminals of the current commutation and breaking unit;

The breaking current branch is connected in parallel with the two bridge arms of the bridge branch; the breaking current branch routing N breaking current modules are connected in series, wherein: N is an integer not less than 1; the breaking current module comprises: parallel Connected non-linear resistor R1 and full control device series valve group;

The high voltage DC circuit breaker adopts any one of the following two connection structures:

The first type: the current commutation and the breaking unit and the on-state current branch are respectively provided with M groups, the on-state current branch and the current commutation and the breaking unit are connected in parallel one-to-one, and all the on-state current branches are connected in parallel Serial connection; wherein M is an integer not less than 1;

The second type: the current commutation and breaking unit is provided with two or more sets, and the on-state current branch is provided with one set, and all the current commutating and breaking units are sequentially connected in series, and are connected in parallel with the on-state current branch.

The current transfer module includes a non-linear resistor R2 and a full control device module connected in parallel, the whole The control device module includes two or more full control devices connected in series, wherein at least two full control devices are connected in reverse series.

The current transfer module includes a non-linear resistor R2 and a full control device module connected in parallel, the full control device module is composed of one or more full bridge submodules connected in series, and the full bridge submodule includes four bridge connections. The full control device has a capacitor connected in parallel across the bridge arm of the full bridge submodule.

The current transfer module includes a non-linear resistor R2 and two sets of one-way flow-through modules. The two-way flow-through modules are connected in anti-parallel connection and connected in parallel with the non-linear resistor R2. The one-way flow-through module includes: at least one pair The full control device and at least one pair of uncontrolled devices, the full control device and the uncontrolled device are connected in series in the same direction.

The current transfer module comprises a non-linear resistor R2, a full control device series module, an uncontrolled device full bridge module, a non-linear resistor, a full control device series module and two bridge arms of the uncontrolled device full bridge module are connected in parallel;

The full control device series module includes at least two full control devices connected in series in the same direction;

Each of the bridge arms of the uncontrolled device full bridge module is formed by a forward series connection of at least two uncontrolled devices, and the midpoints of the two bridge arms serve as input and output terminals of the current transfer module, respectively.

Another object of the present invention is to provide a control method for a high voltage DC circuit breaker:

a) When the DC system is in normal operation, the mechanical switch S is closed, and the full control device in the current transfer module is in an on state; the steady state current flows through the mechanical switch and the current transfer module connected in series in the on-state current branch;

b) When a short circuit fault occurs in the DC system:

1 Firstly open the series control valve group of the full control device of the breaking current branch, and then block the full control device of the current transfer module of the on-state current branch;

2 When the on-state current branch current is completely transferred to the bridge branch and the breaking current branch, the on-state is closed. Mechanical switch S of the current branch;

3 When the mechanical switch S has no arc breaking, the full-control device series valve group of the breaking current branch is blocked, and the fault current is transferred to the non-linear resistor R1 until the system energy is absorbed by the consumption, and the DC circuit breaker is completed. Break.

Compared with the prior art, the beneficial effects achieved by the present invention are:

1. The invention introduces a bridge branch composed of a series valve group of uncontrolled devices, so that the breaking current branch can break the bidirectional line current, significantly reducing the number of full control devices, and controlling the price of the device compared to the control device. The flow capability is strong and far lower than the full control device, so the equipment cost can be greatly reduced;

2. The reversing module of the bridge type branch of the invention is composed of a serially connected valve group and an inductor series connection, and the bridge structure of the uncontrolled device realizes a current commutation function, and the series inductance limits the current commutation process. The rate of change in current produced;

3. When the circuit breaker provided by the invention is in normal operation, the mechanical switch and a small amount of power electronic components pass through, and the on-state loss is small;

4. The circuit breaker provided by the invention can realize the arc-free breaking of the mechanical switch, can prolong the service life of the switch, improve the breaking speed of the switch, and easily realize the voltage equalization problem when the switch is connected in series.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a circuit diagram of a first embodiment of a high voltage DC circuit breaker provided by the present invention.

2 is a circuit diagram of a second embodiment of a high voltage DC circuit breaker provided by the present invention.

3 is a circuit diagram of a third embodiment of a high voltage DC circuit breaker provided by the present invention.

4 is a circuit diagram of a fourth embodiment of a high voltage DC circuit breaker provided by the present invention.

Figure 5 is a circuit diagram of a first embodiment of a current transfer module.

Figure 6 is a circuit diagram of a second embodiment of a current transfer module.

Figure 7 is a circuit diagram of a third embodiment of a current transfer module.

Figure 8 is a circuit diagram of a fourth embodiment of a current transfer module.

detailed description

The invention is further described below in conjunction with the drawings. The following examples are only intended to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of the present invention.

The high voltage DC circuit breaker disclosed by the invention comprises an on-state current branch, a current commutation and a breaking unit.

The on-state current branch includes a mechanical switch S connected in series and a current transfer module including a full control device. The main function of the mechanical switch S is to block the voltage. After the breaking current branch is disconnected, a high breaking voltage will be generated at both ends of the on-state current branch, and the mechanical switch S can withstand a high breaking voltage, so that the current conversion module Withstands a small breaking voltage. The current transfer module contains less full control devices, and the on-resistance of the mechanical switch S is also small. Under normal operating conditions, the loss generated by the line current flowing through the on-state current branch is low.

The current commutation and breaking unit comprises: a bridge branch and a breaking current branch.

The main function of the breaking current branch is to interrupt the fault current in the line and to withstand higher breaking voltages. It consists of N disconnected current modules connected in series, where: N is an integer not less than one. The breaking current module includes: a non-linear resistor R1 connected in parallel and a series valve group of the full control device. When the breaking current branch receives the breaking command, all the control devices in the series valve group of the full control device are synchronously disconnected, and the breaking voltage is generated between the electric node c and the electric node d after the breaking, and the high voltage is connected in parallel at both ends. The impedance of the nonlinear resistor R1 changes, and the final current is switched to the nonlinear resistor R1, and the energy is absorbed by the nonlinear resistor R1. It should be noted that the total number of full control devices applied to the breaking current branch is fixed, and the number of full control devices in the series control valve group of each full control device is evenly distributed according to the number of series control valve groups of the full control device, that is, the value of N is higher. Larger, the smaller the number of fully controlled devices in the series valve group of each full control device. The use of multiple breaking current modules in series is to reduce the size of a single breaking current module and facilitate extended integration.

The bridge branch includes a bridge connection composed of four electrical nodes and four identical commutation modules, wherein: the commutation module D1 and the reversing module D3 are connected in series in the same direction through the electrical node a to form a bridge branch. a bridge arm; a reversing module D2, a reversing module D4 connected in series in the same direction through the electrical node b, forming a second bridge arm of the bridge branch; the reversing module D1 is electrically connected to the reversing module D2 through the electrical node c, reversing The module D3 is electrically connected to the reversing module D4 through the electrical node d, so that the first bridge arm and the second bridge arm are connected in parallel in the same direction. The electrical node a and the electrical node b respectively lead to a connecting line as the connecting end of the current commutation and breaking unit, and the breaking current branch is connected between the electric node c and the electric node d.

The commutation module consists of an uncontrolled device series valve block and an inductor in series. When the current is transferred from the on-state current branch to the bridge branch and the breaking current branch, the current will be quickly transferred due to the fast turn-off speed of the full-control device, and the current flowing through the uncontrolled device of the bridge branch will be rapid. Rising, so the main role of series inductance is to suppress the large current rate of change (di/dt) during commutation to prevent damage to the power device. The bridge structure of the series control valve group of the control device realizes the current commutation function, specifically: when the line current direction is the electrical node a flowing to the electric node b, the current flows through the commutating modules D1 and D4 through the breaking current branch, When the reversing modules D1 and D4 are turned on, the reversing modules D2 and D3 are turned off, and the commutating modules D2 and D3 will withstand high voltage when the breaking current branch is turned off; when the line current direction is the electric node b flowing to the electric node a When the current flows through the reversing modules D2 and D3 through the breaking current branch, the reversing modules D2 and D3 are turned on, the reversing modules D1 and D4 are turned off, and the switching module D1 is turned off when the breaking current branch is turned off. The D4 will withstand high voltages.

The specific connection structure of the high voltage DC circuit breaker will be further described in detail below with reference to specific embodiments:

The first embodiment of the high voltage DC circuit breaker:

As shown in Fig. 1, a set of on-state current branch, current commutation and breaking unit are provided, and an on-state current branch is connected in parallel at both ends of the current commutation and breaking unit. The breaking current branch is also provided with only one breaking current module: a non-linear resistor R1 and a full-scale series connection of multiple full-control devices. The control device is connected in series, and the non-linear resistor R1 is connected in parallel with the series valve group of the full control device.

The second embodiment of the high voltage DC circuit breaker:

As shown in FIG. 2, the difference from the first embodiment of the high voltage DC circuit breaker is that the current commutation and the breaking unit are provided with multiple groups, and the plurality of sets of current commutation and breaking units are sequentially connected in series, and then connected to the on state. Current branch connection.

The third embodiment of the high voltage DC circuit breaker:

As shown in FIG. 3, the difference from the first embodiment of the high voltage DC circuit breaker is that the breaking current branch in the current commutating breaking unit is provided with a plurality of non-linear resistors R1 connected in series, and each non-linear resistor R1 There is a set of full control device series valve group in parallel at both ends, but in this embodiment, the number of full control devices in the series control valve group of all the full control devices and the high voltage DC circuit breaker in the first embodiment of the full control device series valve group The number of control devices is equal. In this embodiment, the number of full control devices in the series control valve group of each full control device is equally distributed according to the number of groups of the full control device series valve group. This connection structure can reduce the volume of a single breaking current module.

Fourth embodiment of high voltage DC circuit breaker:

As shown in FIG. 4, the difference from the first embodiment of the high-voltage DC circuit breaker is that: the on-state current branch, the current commutation and the breaking unit are provided with multiple groups, and all on-state current branches are connected in series in sequence. The current commutation and the breaking unit are connected in parallel with the on-state current branch in one-to-one correspondence.

The fifth embodiment of the high voltage DC circuit breaker:

The difference from the second embodiment of the high voltage DC circuit breaker is that the breaking current branch adopts the breaking current branch in the third embodiment of the high voltage DC circuit breaker.

The sixth embodiment of the high voltage DC circuit breaker:

The difference from the fourth embodiment of the high voltage DC circuit breaker is that the breaking current branch adopts high voltage straight The breaking current branch in the third embodiment of the flow breaker.

The foregoing current transfer module has the following four embodiments. All of the above high voltage DC segmenter structures can adopt any one of the following four current transfer modules. The current transfer module is further described below with reference to FIG. 5 to FIG. .

Current transfer module first embodiment:

As shown in FIG. 5, the current transfer module includes a non-linear resistor R2 and a full control device module connected in parallel, and the full control device module includes two or more full control devices connected in series, wherein at least two full control devices are connected in reverse series.

Current transfer module second embodiment:

As shown in FIG. 6, the current transfer module includes a non-linear resistor R2 and a full-control device module connected in parallel. The full-control device module is composed of one or two full-bridge sub-modules connected in series, and the full-bridge sub-module includes four bridge connections. The full control device has a capacitor connected in parallel across the bridge arm of the full bridge submodule.

Current transfer module third embodiment:

As shown in FIG. 7, the current transfer module includes a non-linear resistor R2 and two sets of unidirectional current-passing modules. The two-way flow-through modules are connected in reverse parallel connection with the non-linear resistor R2; the one-way flow-through module includes: A pair of full control devices and at least one pair of uncontrolled devices, the full control device and the uncontrolled device are connected in series in the same direction.

Current transfer module fourth embodiment:

As shown in FIG. 8, the current transfer module includes a non-linear resistor R2, a full-control device series module, an uncontrolled device full-bridge module, a non-linear resistor, a full-control device series module, and an uncontrolled device full-bridge module. Connection; the full control device series module includes at least two full control devices connected in series in the same direction; each control arm of the control device full bridge module is composed of at least two uncontrolled devices connected in series in the forward direction, and the midpoint of the two bridge arms Used as the input and output of the current transfer module.

All of the above fully controlled devices are required to have the ability to turn on and off current. The gate-off devices IGBT, EGBT, GTO, MOSFET, etc. can be used. The uncontrolled device does not need to have the ability to turn on and off current. diode.

When in use, the high-voltage DC circuit breaker is connected in series to the DC system through the electrical node a and the electrical node b, and the commutation of the full-bridge circuit without controlling the device can significantly reduce the number of full-control devices and reduce the equipment cost.

The invention provides a control method for a high-voltage DC circuit breaker, which can adopt any of the above-mentioned high-voltage DC circuit breaker structures, and the specific control method is as follows:

b) When a short circuit fault occurs in the DC system:

2 When the on-state current branch current is completely transferred to the bridge branch and the breaking current branch, the mechanical switch S of the on-state current branch is closed;

The above is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention. It should also be considered as the scope of protection of the present invention.

Claims

A high voltage DC circuit breaker, comprising: an on-state current branch, a current commutation and a breaking unit; the on-state current branch comprises a series connection: a mechanical switch S and a current transfer module including a full control device;

The current commutation and breaking unit comprises: a bridge branch and a breaking current branch;

The bridge branch includes: two identical bridge arms in the same direction, the bridge arm is composed of two commutation modules connected in series in the same direction, and the commutation module is composed of an uncontrolled device series valve group and an inductor Connected in series; the connecting node of the two commutation modules of the two bridge arms serves as two terminals of the current commutation and breaking unit;

The breaking current branch is connected in parallel with the two bridge arms of the bridge branch; the breaking current branch routing N breaking current modules are connected in series, wherein: N is an integer not less than 1; the breaking current module comprises: parallel Connected non-linear resistor R1 and full control device series valve group;

The high voltage DC circuit breaker adopts any one of the following two connection structures:

The first type: the current commutation and the breaking unit and the on-state current branch are respectively provided with M groups, the on-state current branch and the current commutation and the breaking unit are connected in parallel one-to-one, and all the on-state current branches are connected in parallel Serial connection; wherein M is an integer not less than 1;

The second type: the current commutation and breaking unit is provided with two or more sets, and the on-state current branch is provided with one set, and all the current commutating and breaking units are sequentially connected in series, and are connected in parallel with the on-state current branch.
The high voltage DC circuit breaker according to claim 1, wherein the current transfer module comprises a non-linear resistor R2 and a full control device module connected in parallel, and the full control device module comprises two or more full control connected in series The device, wherein at least two of the full control devices are connected in reverse series.
The high voltage DC circuit breaker according to claim 1, wherein said current transfer module comprises a non-linear resistor R2 and a full control device module connected in parallel, said full control device module being one or Two or more full-bridge sub-modules are connected in series, and the full-bridge sub-module includes four bridge-connected full-control devices, and capacitors are also connected in parallel across the bridge arms of the full-bridge sub-module.
The high voltage DC circuit breaker according to claim 1, wherein the current transfer module comprises a non-linear resistor R2 and two sets of one-way flow-through modules, and the two-way flow-through modules are connected in anti-parallel and non-linear resistors. R2 is connected in parallel; the one-way flow module comprises: at least one pair of full control devices and at least one pair of uncontrolled devices, and the full control device is connected in series with the uncontrolled device in the same direction.
The high voltage DC circuit breaker according to claim 1, wherein the current transfer module comprises a non-linear resistor R2, a full control device series module, an uncontrolled device full bridge module, a non-linear resistor, a full control device series module and The two bridge arms of the full bridge module of the uncontrolled device are connected in parallel;

The full control device series module includes at least two full control devices connected in series in the same direction;

Each of the bridge arms of the uncontrolled device full bridge module is formed by a forward series connection of at least two uncontrolled devices, and the midpoints of the two bridge arms serve as input and output terminals of the current transfer module, respectively.
A control method for a high voltage DC circuit breaker, characterized in that:

a) When the DC system is in normal operation, the mechanical switch S is closed, and the full control device in the current transfer module is in an on state; the steady state current flows through the mechanical switch and the current transfer module connected in series in the on-state current branch;

b) When a short circuit fault occurs in the DC system:

1 Firstly open the series control valve group of the full control device of the breaking current branch, and then block the full control device of the current transfer module of the on-state current branch;

2 When the on-state current branch current is completely transferred to the bridge branch and the breaking current branch, the mechanical switch S of the on-state current branch is closed;

3 When the mechanical switch S has no arc breaking, the full-control device series valve group of the breaking current branch is blocked, this The fault current is transferred to the non-linear resistor R1 until the system energy is absorbed by it, and the DC breaker completes the breaking.