WO2021114599A1

WO2021114599A1 - Passive semi-controlled hybrid direct current circuit breaker and control method therefor

Info

Publication number: WO2021114599A1
Application number: PCT/CN2020/096248
Authority: WO
Inventors: 周万迪; 魏晓光; 李弸智; 高冲; 郭亮; 张升
Original assignee: 全球能源互联网研究院有限公司; 国家电网有限公司
Priority date: 2019-12-11
Filing date: 2020-06-16
Publication date: 2021-06-17
Also published as: CN111030042A

Abstract

A passive semi-controlled hybrid direct current circuit breaker and a control method therefor. The passive semi-controlled hybrid direct current circuit breaker comprises: a quick mechanical switch K, a resonant module, an energy-consuming branch configured to absorb a fault current, a thyristor T1, and a thyristor T2. Two ends of the quick mechanical switch K are both connected to a direct current circuit to constitute a main flow-through branch; the thyristor T1 and the thyristor T2 are anti-parallelly connected and then series-connected to the resonant module to constitute a transfer branch; the transfer branch and the energy-consuming branch are parallelly connected to the quick mechanical switch K; and the cathode of the thyristor T1 is connected to the quick mechanical switch K.

Description

Passive semi-control hybrid DC circuit breaker and control method thereof

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 201911264604.6 on December 11, 2019. The entire content of this application is incorporated into this application by reference.

Technical field

This application relates to the field of power electronics technology, for example, to a passive semi-controlled hybrid DC circuit breaker and a control method thereof.

Background technique

Large-scale grid integration and consumption of clean energy such as wind and solar have put forward demands for the development of DC transmission and distribution systems. High-voltage DC circuit breakers are the key equipment for the reliable, economic and flexible operation of DC systems. The DC circuit breaker that mixes mechanical switches and power electronic devices has both the low loss characteristics of mechanical switches and the fast breaking characteristics of power electronic devices. It is the most effective technical way to achieve rapid current breaking in the application of DC systems. Hybrid DC circuit breakers generally use full control devices, and the breaking current is limited by the breaking current capability of the full control devices, and the cost is relatively high, which limits its wide application in weakly damped DC transmission and distribution systems.

Although the hybrid DC circuit breaker based on thyristor in the related technology can significantly improve the breaking current capacity of the DC circuit breaker, the thyristor cannot self-shut off. The realization of the internal current transfer of the DC circuit breaker needs to rely on pre-stored capacitors, reactance and other passive components achieve. The method of precharging the capacitor by the energy supply system can realize the internal current transfer of the DC circuit breaker, but the DC circuit breaker has high loss and cost, large volume, and the overall reliability of the DC circuit breaker is low.

Summary of the invention

This application provides a passive semi-controlled hybrid DC circuit breaker and a control method thereof, which significantly reduces the loss and cost of the DC circuit breaker, and at the same time, the DC circuit breaker capacitor can be precharged through the DC system, thereby reducing the DC circuit breaker The volume of the device improves the overall reliability of the DC circuit breaker.

The embodiment of the application provides a passive semi-controlled hybrid DC circuit breaker, including: a fast mechanical switch K, a resonance module, an energy-consuming branch set to absorb fault current, a thyristor T1 and a thyristor T2;

Both ends of the fast mechanical switch K are connected to a DC line to form a main flow branch;

The thyristor T1 and the thyristor T2 are connected in anti-parallel connection with the resonant module to form a transfer branch;

The transfer branch and the energy-consuming branch are connected in parallel with the main flow branch;

The cathode of the thyristor T1 is connected to the fast mechanical switch K.

The embodiment of the present application also provides a control method of a passive semi-controlled hybrid DC circuit breaker, including:

When the DC circuit breaker is put into operation, controlling the fast mechanical switch K of the DC circuit breaker to close so that the normal working current of the DC line flows through the main current branch of the DC circuit breaker;

In the event of a failure on the line side of the DC circuit breaker, the fast mechanical switch K of the DC circuit breaker is controlled to open, and the thyristor T2 and the thyristor T1 of the DC circuit breaker are triggered in turn, so that the DC circuit breaker The energy-consuming branch absorbs fault current;

In the event of a failure on the power supply side of the DC circuit breaker, the fast mechanical switch K of the DC circuit breaker is controlled to open, and the thyristor T2 of the DC circuit breaker is triggered to make the energy-consuming branch of the DC circuit breaker Absorb fault current.

Description of the drawings

Fig. 1 is a topological structure diagram of a passive semi-controlled hybrid DC circuit breaker provided by an embodiment of the present application;

2 is a schematic diagram of the fast mechanical switch K not closing when the DC circuit breaker is put into operation according to an embodiment of the present application;

3 is a schematic diagram of the fast mechanical switch K closing when the DC circuit breaker is put into operation according to an embodiment of the present application;

4 is a schematic diagram of a fast mechanical switch K opening when a fault occurs on the line side according to an embodiment of the present application;

5 is a schematic diagram of capacitor discharge when a fault occurs on the line side according to an embodiment of the present application;

6 is a schematic diagram of a thyristor triggered after a capacitor oscillation is reversed when a fault occurs on the line side according to an embodiment of the present application;

FIG. 7 is a schematic diagram of capacitor charging when a fault occurs on the line side according to an embodiment of the present application; FIG.

FIG. 8 is a schematic diagram of an energy-consuming branch absorbing fault current when a fault occurs on the line side according to an embodiment of the present application;

9 is a schematic diagram of a fast mechanical switch K opening when a fault occurs on the power supply side according to an embodiment of the present application;

10 is a schematic diagram of capacitor discharge when a fault occurs on the power supply side according to an embodiment of the present application;

FIG. 11 is a schematic diagram of capacitor charging when a fault occurs on the power supply side according to an embodiment of the present application;

Fig. 12 is a schematic diagram of an energy-consuming branch absorbing fault current when a fault occurs on the power supply side according to an embodiment of the present application.

Detailed ways

The application will be described below in conjunction with the drawings.

The embodiment of the application provides a passive semi-controlled hybrid DC circuit breaker, which is set on a DC line. The topological structure is shown in Fig. 1, and includes a fast mechanical switch K, a resonance module, and energy consumption configured to absorb fault current. The branch, thyristor T1 and thyristor T2; both ends of the fast mechanical switch K are connected to the DC line to form the main flow branch; the thyristor T1 and the thyristor T2 are connected in series with the resonant module to form the transfer branch; the transfer branch, consumption The energy branch is connected in parallel with the main flow branch; and the cathode of the thyristor T1 is connected to the fast mechanical switch K.

The resonant module includes a capacitor C and an inductance L; the capacitor C, the inductance L, and the anti-parallel circuit composed of the thyristor T1 and the thyristor T2 are connected in series in sequence.

The transfer branch also includes a resistor R; one end of the resistor R is connected between the inductor L and the anti-parallel circuit composed of the thyristor T1 and the thyristor T2, and the other end of the resistor R is grounded. Since the thyristor T1 and the thyristor T2 are anti-parallel, when the cathode of the thyristor T1 is connected to the fast mechanical switch K, the anode of the thyristor T2 is connected to the fast mechanical switch K.

The energy-consuming branch includes one or more lightning arresters connected in series.

The passive semi-controlled hybrid DC circuit breaker provided by the embodiment of the application includes a fast mechanical switch K, a resonance module, an energy-consuming branch set to absorb fault current, a thyristor T1 and a thyristor T2; both ends of the fast mechanical switch K are Connect the DC line to form the main flow branch; the thyristor T1 and the thyristor T2 are anti-parallel and connected in series with the resonant module to form a transfer branch; the transfer branch and the energy-consuming branch are connected in parallel with the main flow branch; and the cathode of the thyristor T1 is connected The fast mechanical switch K greatly reduces the loss and cost of the DC circuit breaker, reduces the volume of the DC circuit breaker, and improves the overall reliability of the DC circuit breaker. The DC circuit breaker provided by the embodiments of the present application can realize bidirectional and fast switching of DC current, and has low operating loss. The main current flow branch is only composed of fast mechanical switches, and the DC circuit breaker topology on-state loss is negligible and does not need to be Equipped with a water-cooling system, with strong overload capacity, the breaking current can reach tens of kA, which meets the application requirements of DC transmission and distribution systems; the DC circuit breaker provided by the embodiments of this application is less difficult to design and integrate, and mainly adopts semi-controlled power electronic devices , The technology is mature, the cost is low, and the economy of the DC circuit breaker can be improved; the DC circuit breaker provided by the embodiment of the application does not need to be equipped with a high-voltage isolation auxiliary power supply, which simplifies the equipment structure, improves the reliability, and effectively reduces the equipment footprint .

Example 2

Embodiment 2 of the present application provides a control method of a passive semi-controlled hybrid DC circuit breaker. The passive semi-controlled hybrid DC circuit breaker is divided into operation (that is, normal operation), failure on the line side, and occurrence on the power supply side. There are three fault conditions, and the control methods include:

When the DC circuit breaker is put into operation, the fast mechanical switch K is controlled to close, and the DC line current i flows through the main current branch, as shown in Figure 3; when a fault occurs on the line side of the DC circuit breaker, the fast mechanical switch K is controlled. Then, the thyristor T2 and the thyristor T1 are triggered in turn, and then the energy-consuming branch absorbs the fault current; when the DC circuit breaker power side fails, the fast mechanical switch K is controlled to open, triggering the thyristor T2, and then the energy-consuming branch absorbs the fault current .

When the DC circuit breaker is put into operation, the fast mechanical switch K is controlled to close. Before the DC line current flows through the main current branch, the fast mechanical switch K is not closed, and the capacitor C is charged through the circuit composed of the capacitor C, the inductor L, the resistor R and the earth, and the thyristor T1 and the thyristor T2 are both blocked, as shown in the figure 2 shown.

When a fault occurs on the line side of the DC circuit breaker, the fast mechanical switch K is controlled to open, and then the thyristor T2 and the thyristor T1 are triggered in sequence, and then the energy-consuming branch absorbs the fault current, including:

When the DC circuit breaker receives the breaking command or reaches the overcurrent protection setting value, it controls the fast mechanical switch K to open, as shown in Figure 4; after the fast mechanical switch K opens to a sufficient distance, the thyristor T2 and the capacitor C are triggered After the fast mechanical switch K, the thyristor T2 and the inductor L are discharged, the main branch current is superimposed on the oscillating current i _LC , as shown in Figure 5; after the capacitor C oscillates in the reverse direction, the thyristor T1 is triggered, and the main branch The current superimposes the reverse oscillating current i _LC , as shown in Figure 6, causing the current to cross zero, and the arc of the fast mechanical switch K is extinguished; the fault current charges the capacitor C, and the voltage of the capacitor C rises, as shown in Figure 7; when the capacitor C The voltage reaches the action voltage of the energy-consuming branch, the fault current is commutated to the energy-consuming branch, the energy-consuming branch absorbs the fault current, and completes the fault current breaking, as shown in Figure 8.

When a fault occurs on the power supply side of the DC circuit breaker, the fast mechanical switch K is controlled to open, and the thyristor T2 is triggered, and then the energy-consuming branch absorbs the fault current, including:

When the DC circuit breaker receives the breaking command or reaches the overcurrent protection setting value, the fast mechanical switch K is controlled to open, as shown in Figure 9; after the fast mechanical switch K is opened to a sufficient distance, the thyristor T2 is triggered, The capacitor C is discharged through the loop formed by the fast mechanical switch K, the thyristor T2 and the inductance L. The main branch current is superimposed with the reverse oscillating current L, as shown in Figure 10, causing the current to cross zero and the arc is extinguished; the fast mechanical switch K current After breaking, the fault current is transferred to the transfer branch, and the capacitor C is charged, and the voltage of the capacitor C rises, as shown in Figure 11. When the voltage of the capacitor C reaches the operating voltage of the energy-consuming branch, the fault current is commutated to the energy-consuming branch The energy-consuming branch absorbs the fault current and completes the fault current breaking, as shown in Figure 12.

Claims

A passive semi-controlled hybrid DC circuit breaker, including: a fast mechanical switch K, a resonance module, an energy-consuming branch set to absorb fault current, a thyristor T1 and a thyristor T2;

Both ends of the fast mechanical switch K are connected to a DC line to form a main flow branch;

The thyristor T1 and the thyristor T2 are connected in anti-parallel connection with the resonant module to form a transfer branch;

The transfer branch and the energy-consuming branch are connected in parallel with the main flow branch;

The cathode of the thyristor T1 is connected to the fast mechanical switch K.
The DC circuit breaker according to claim 1, wherein the resonance module includes a capacitor C and an inductance L;

The capacitor C, the inductor L, and the anti-parallel circuit composed of the thyristor T1 and the thyristor T2 are connected in series in sequence.
The DC circuit breaker according to claim 2, wherein the transfer branch further comprises a resistor R; one end of the resistor R is connected to the inductance L and an anti-parallel connection composed of the thyristor T1 and the thyristor T2 Between the circuits, the other end of the resistor R is grounded.
The DC circuit breaker according to claim 1, wherein the energy-consuming branch includes one or more lightning arresters connected in series.
A control method of a passive semi-controlled hybrid DC circuit breaker includes:

When the DC circuit breaker is put into operation, controlling the fast mechanical switch K of the DC circuit breaker to close so that the normal working current of the DC line flows through the main current branch of the DC circuit breaker;

In the event of a failure on the line side of the DC circuit breaker, the fast mechanical switch K of the DC circuit breaker is controlled to open, and the thyristor T2 and the thyristor T1 of the DC circuit breaker are triggered in turn, so that the DC circuit breaker The energy-consuming branch absorbs fault current;

In the event of a failure on the power supply side of the DC circuit breaker, the fast mechanical switch K of the DC circuit breaker is controlled to open, and the thyristor T2 of the DC circuit breaker is triggered to make the energy-consuming branch of the DC circuit breaker Absorb fault current.
The method according to claim 5, in the case that the DC circuit breaker is put into operation, the fast mechanical switch K of the DC circuit breaker is controlled to close, so that the normal working current of the DC line flows through the DC circuit breaker Before the main flow branch of the device, it also includes:

The capacitor C of the resonance module of the DC circuit breaker is charged, so that both the thyristor T1 and the thyristor T2 are blocked.
The method according to claim 5, wherein in the case of a fault on the line side of the DC circuit breaker, the quick mechanical switch K of the DC circuit breaker is controlled to open, and the thyristors of the DC circuit breaker are sequentially triggered T2 and thyristor T1 to make the energy-consuming branch of the DC circuit breaker absorb fault current, including:

Controlling the fast mechanical switch K to open when the DC circuit breaker receives a breaking command or reaches a fixed value of overcurrent protection;

Trigger the thyristor T2 to discharge the capacitor C;

After the capacitor C oscillates in the reverse direction, the thyristor T1 is triggered to charge the capacitor C, and when the voltage of the capacitor C reaches the operating voltage of the energy-consuming branch, the The energy-consuming branch absorbs the fault current.
The method according to claim 5, wherein, in the case of a failure on the power supply side of the DC circuit breaker, the fast mechanical switch K of the DC circuit breaker is controlled to open, and the thyristor T2 of the DC circuit breaker is triggered to Making the energy-consuming branch of the DC circuit breaker absorb fault current includes:

Controlling the fast mechanical switch K to open when the DC circuit breaker receives a breaking command or reaches a fixed value of overcurrent protection;

Trigger the thyristor T2 to discharge the capacitor C. After the mechanical switch K is switched off, the capacitor C is charged. When the voltage of the capacitor C reaches the operating voltage of the energy-consuming branch In the case of, the energy-consuming branch is made to absorb the fault current.