CN103296636B - A kind of HVDC gas-break switch based on self-maintained circuit - Google Patents

Abstract

The invention discloses a high-voltage DC gas circuit breaker based on a self-excited oscillation circuit, which can break fault currents at a higher rated voltage level; it includes a superconducting current limiter and a breaking module connected in series, the breaking The module includes a gas circuit breaker connected in parallel, a commutation circuit composed of a capacitor and an inductor in series, and a non-linear resistor zinc oxide energy absorbing device; the fault current is first limited by the superconducting current limiter and then interrupted by the gas circuit breaker, so as to achieve For the purpose of breaking the fault current, the gas circuit breaker uses self-excitation to generate an artificial zero-crossing point to extinguish the arc; the invention has the advantages of fast response, low current overload coefficient, simple structure, small size, low overvoltage, safety and reliability, and makes the circuit The short-circuit current value will not exceed the quench current value of the superconducting current limiter, which can protect other equipment.

Description

A High Voltage DC Gas Circuit Breaker Based on Self-excited Oscillating Circuit

technical field

The invention relates to the technical field of circuit breakers, in particular to a high-voltage DC gas circuit breaker based on a self-excited oscillation circuit.

Background technique

Due to the immature technology of high-voltage DC circuit breakers, the development of multi-terminal DC systems is limited, and it has become a bottleneck in the development and application of multi-terminal DC transmission technology. As for the emerging flexible DC transmission system, although the power electronic technology can directly control and protect the system, as the final protection unit, the DC circuit breaker is also indispensable.

At present, the principles of the commonly used high-voltage DC circuit breakers are self-excited oscillation type, which excites the oscillation type and uses the current limiting device to limit the current first and then break the type. Using a current limiter to first limit the current and then break it is a hot research direction today, which is also inseparable from the rapid development of the current current limiting technology. There are two main reasons why current limiting technology has attracted attention: First, as the capacity of the power grid continues to increase, the level of short-circuit current also increases. Limiting short-circuit current can improve the safety and stability of the power system, the quality of power supply of the power grid, and the operation of the power grid. Flexibility; Second, the existing power devices have low overload capacity, and the di/dt and du/dt that can be tolerated are limited. In order to prevent breakdown or damage to the power devices when a fault occurs, a current limiter is required. The invention adopts the method of connecting the superconducting current limiter and the self-excited hydrogen circuit breaker in series to form a high-voltage gas circuit breaker.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the object of the present invention is to provide a high-voltage DC gas circuit breaker based on a self-excited oscillation circuit, which can be used in high-voltage occasions and has the ability to break large fault currents and rated currents, and Break the circuit when the current crosses zero.

To achieve the above object, the present invention adopts the following technical solutions:

A high-voltage DC gas circuit breaker based on a self-excited oscillation circuit, comprising a superconducting current limiter 1 connected in series and a breaking module, the breaking module comprising a gas circuit breaker 2 connected in parallel, a capacitor 3 and an inductor 4 connected in series The commutation circuit and the non-linear resistance zinc oxide energy absorbing device 5.

The gas circuit breaker 2 is a hydrogen circuit breaker, the gas in which is pure hydrogen or a mixed gas of hydrogen and other gases, if it is a mixed gas, hydrogen and other gases are mixed in any ratio.

The superconducting current limiter 1 is a high temperature resistance superconducting current limiter, and its material is YBCO or other superconducting materials.

The superconducting current limiter 1 adopts a series and/or parallel structure for multiple superconducting current limiters, and the breaking module adopts a series and/or parallel structure for multiple breaking modules.

A voltage equalizing resistor 6 is connected in parallel to each gas circuit breaker 2 .

Adding a magnetic field to the gas circuit breaker 2 improves its breaking capacity.

The way to increase the magnetic field is to increase the magnetic field outside the gas circuit breaker 2 or slot the contacts of the gas circuit breaker 2 .

Compared with the prior art, the present invention has the following advantages:

1. The present invention adopts a gas circuit breaker, because the gas circuit breaker has a large current and strong breaking capacity, and can withstand a high rated voltage; since the DC current has no natural zero-crossing point, the arc in the fracture is not easy to extinguish, when the rated voltage of the circuit is higher than that of hydrogen When the arc voltage of the arc is low, the arc cannot be extinguished, so the method of creating an artificial zero-crossing point is used to reduce the DC current to zero to extinguish the arc. Because the hydrogen arc has the characteristics of negative resistance, the negative resistance characteristics and instability of the hydrogen arc can be used to generate incremental self-excited oscillations in the series circuit of capacitance and inductance in parallel with the breaking arc gap, so that the opening of the arc gap Superimpose the oscillating current with increased amplitude on the DC current, and use the current to break the circuit when it crosses zero;

2. The superconducting current limiter of the present invention is a high-temperature resistive superconducting current limiter. The resistive superconducting current limiter has the characteristics of simple structure, fast response speed and low current overload coefficient; the material adopts yttrium barium copper oxide YBCO, Because its resistance is very large during quenching, the fault current can be limited to a very low level; the gas circuit breaker 2 of the present invention is a hydrogen circuit breaker, and hydrogen is used as an arc extinguishing gas, which can provide high arc voltage and the time when the arc is extinguished The constant is small, the volume of the hydrogen circuit breaker equipment is small, and the stability is high; when the gas in the hydrogen circuit breaker is a mixture of hydrogen and other gases, the mixture can improve the stability of the gas or improve the insulation capacity of the gas;

3. The superconducting current limiter 1 adopts a series and/or parallel structure for multiple superconducting current limiters, and the breaking module adopts a series and/or parallel structure for multiple breaking modules; when the superconducting current limiter and The breaking module adopts the form of multiple series connection, which can increase the rated voltage of the high voltage DC gas circuit breaker of the present invention; when the superconducting current limiter and the breaking module adopt the form of multiple parallel connection, it can increase the rated voltage of the high voltage DC gas circuit breaker of the present invention. rated current;

4. There is a voltage equalizing resistor connected in parallel to each gas circuit breaker, so that each gas circuit breaker bears the same rated voltage and achieves the purpose of voltage equalization.

Description of drawings

Fig. 1 is a schematic structural view of the present invention.

Fig. 2 is a schematic diagram of the first improved breaking module.

Fig. 3 is a schematic diagram of the second improved breaking module.

Fig. 4 is a schematic diagram of a third improved breaking module.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, a high-voltage DC gas circuit breaker based on a self-excited oscillation circuit in the present invention includes a series-connected superconducting current limiter 1 and a breaking module, and the breaking module includes a phase-parallel gas circuit breaker 2, A commutation circuit composed of a capacitor 3 and an inductor 4 connected in series and a non-linear resistor zinc oxide energy absorbing device 5 .

As a preferred embodiment of the present invention, the gas circuit breaker 2 is a hydrogen circuit breaker, the gas in which is pure hydrogen or a mixture of hydrogen and other gases, such as a mixture of hydrogen and nitrogen. The superconducting current limiter 1 is a high temperature resistance superconducting current limiter, and its material is YBCO. By adding a magnetic field to the superconducting strip, the critical current value of superconducting is increased, and the ability to break the current is greatly improved, making the breaking faster.

As a preferred embodiment of the present invention, if the rated voltage value that the gas circuit breaker can bear does not meet the requirements of the system, in order to increase the rated voltage of the high voltage DC gas circuit breaker of the present invention, multiple breaking modules can be connected in series, A plurality of superconducting current limiters can also be connected in series. If the rated current value that the gas circuit breaker can bear does not meet the requirements of the system, in order to increase the rated current of the high-voltage DC gas circuit breaker of the present invention, multiple breaking modules can be connected in parallel, and the superconducting current limiter can also be used Multiple parallel forms. As shown in Fig. 2, it is a structure in which multiple breaking modules are connected in parallel to increase the rated current of the high-voltage DC gas circuit breaker of the present invention. As shown in FIG. 3 , a plurality of breaking modules are first connected in series and then connected in parallel, which reduces the time distribution of the breaking modules. As shown in Figure 4, it is a structure in which multiple breaking modules are connected in series. Using the structure in Figure 3 and Figure 4 can reduce the number of inductance and capacitance in the circuit. Two inductors can be connected in series with another large inductance, and two capacitors can be Replacing it with another capacitor, thereby reducing the size and the number of inductances in the circuit, will also reduce the influence of coupled inductance, making the breaking time of the breaking module closer.

As a further preferred embodiment of the present invention, each gas circuit breaker 2 in Figs. 2-4 is connected in parallel with a voltage equalizing resistor 6, so that each gas circuit breaker 2 bears the same rated voltage for the purpose of voltage equalization.

As a preferred embodiment of the present invention, in order to improve the breaking capacity of the gas circuit breaker, it is possible to add a magnetic field to the gas circuit breaker 2, such as applying an external magnetic field or generating a magnetic field by slotting the contacts of the gas circuit breaker. The magnetic field can The electric arc is elongated, thereby increasing the current value that can be broken, and improving the arc extinguishing ability of the gas circuit breaker 2 .

The working principle of the present invention is as follows: the superconducting current limiter 1 first limits the fault current to the current value that the gas circuit breaker can break, and then the gas circuit breaker directly extinguishes the DC current; the capacitor 3 and the inductor 4 are connected in series. The current circuit is connected in parallel to the gas circuit breaker. When the contacts of the gas circuit breaker are separated, the capacitor 3 is charged by the arc voltage. Due to the instability of the arc, the arc voltage fluctuates, so that there is a charging and discharging process between the capacitor 3 and the arc, and a charging and discharging current is generated. The negative resistance characteristic of the arc makes the oscillation of this current increase continuously. When the amplitude of the current is equal to When the current is interrupted, a current zero crossing occurs between the contacts of the gas circuit breaker. After the arc current crosses zero, the dielectric recovery stage begins between the contacts of the gas circuit breaker. At this time, the DC system still stores huge energy, and this part of energy will become the recovery voltage on the capacitor 3. Only when the gas circuit breaker has a faster The recovery speed of the medium will not cause re-ignition. When the recovery voltage rises to the rated voltage of the parallel-connected non-linear resistor zinc oxide energy absorbing device 5, the energy absorbing device is turned on, absorbing this part of energy, and reducing the system current to zero, thus completing a DC breaking process.

The present invention adopts the superconducting current limiter to limit the current because the superconducting current limiter can operate under high voltage, can realize the integration of detection, conversion and current limiting, and can limit the fault current in millisecond level. The start-up of the current-limiting effect of the superconducting current limiter does not depend on other control circuits, and the increase of the line current is the command signal for the quenching of the superconductor.

Claims (5)

1. a HVDC gas-break switch based on self-maintained circuit, it is characterised in that: include the superconduction limit being in series Stream device (1) and multiple module of cut-offfing, described superconductive current limiter (1) is high-temperature electric resistance type superconductive current limiter, described superconductive current limiter Superconductor use yttrium barium copper oxide YBCO；Described cut-off gas-break switch (2), the electric capacity (3) that module includes being in parallel The converter circuit being composed in series with inductance (4) and nonlinear resistance zinc oxide energy absorption device (5)；Described gas-break switch (2) For hydrogen chopper, gas therein is pure hydrogen or hydrogen and the mixed gas of other gas, if mixed gas, hydrogen and Other gas mixes with arbitrary proportion；The described converter circuit cut-off in module and nonlinear resistance zinc oxide energy absorption device (5) The mode of connection, use structure directly the most in parallel with gas-break switch (2), or each cut-off the converter circuit in module and non- Linear resistance zinc oxide energy absorption device (5) all first self connects two or more, then with gas-break switch (2) in parallel connecing Line structure.

A kind of HVDC gas-break switch based on self-maintained circuit the most according to claim 1, it is characterised in that: Described superconductive current limiter (1) is multiple, use series connection and/or the structure of parallel connection, the plurality of cut-off module use series connection and/or Structure in parallel.

A kind of HVDC gas-break switch based on self-maintained circuit the most according to claim 1, it is characterised in that: Each described gas-break switch (2) is parallel with equalizing resistance (6).

A kind of HVDC gas-break switch based on self-maintained circuit the most according to claim 1, it is characterised in that: Increase the mode in magnetic field to described gas-break switch (2), improve its connecting-disconnecting function.

A kind of HVDC gas-break switch based on self-maintained circuit the most according to claim 4, it is characterised in that: The mode in described increase magnetic field is to increase outward magnetic field at gas-break switch (2) or slot on the contact of gas-break switch (2).