CN104600758A - Self energy taking device of high voltage direct current circuit breaker and implementing method thereof - Google Patents

Abstract

The invention discloses a self-energy harvesting device of a high-voltage direct current circuit breaker and a method for realizing the self-energy harvesting device. The voltage stabilizing circuit is composed, and the realization method of the self-energy harvesting device includes the following steps: connecting the line energy harvesting unit in series with the main branch of the high-voltage DC circuit breaker, and obtaining the energy from the current of the main branch energy; when the current flows through the main branch, control the on and off of the switching tube; adjust the charging time of the capacitor to control the voltage range of the capacitor. The technical solution provided by the invention utilizes the energy in the line without needing an additional separate power supply, and is suitable for DC circuit breakers with a hybrid type of mechanical switches and power electronic devices, and when used in a current limiting device composed of multiple DC circuit breakers in series , compared with the scheme of supplying power through a high-frequency transformer from a low potential, the insulation requirements for the high-frequency transformer are reduced.

Description

A self-energy harvesting device for a high-voltage DC circuit breaker and its realization method

technical field

The invention relates to a power electronic device, in particular to a self-energy harvesting device of a high-voltage direct current circuit breaker and a realization method thereof.

Background technique

High-voltage DC circuit breakers are mainly used in DC transmission and distribution lines to break the current of DC lines. In order to reduce the on-state loss and shorten the operating time of the circuit breaker, DC circuit breakers using a hybrid of mechanical switches and power electronic devices have received more and more attention, and a variety of topologies have been derived. When this type of DC circuit breaker is in normal operation, the current flows through the mechanical switch. When an overcurrent fault occurs in the line, the current is transferred to the branch circuit of the power electronic device connected in parallel, and then the power electronic device breaks the current.

For example, the circuit breaker introduced in the patent with application number 20130051175.9 belongs to this type of circuit breaker. The mechanical switch branch through which current flows during normal operation in this type of DC circuit breaker is called the main branch. Power electronic devices used for breaking current Branches are called transfer branches. Since the voltage of the DC line is as high as tens to hundreds of kilovolts, and the withstand voltage of the power electronic device is relatively small, when the power electronic device is applied to the DC line, it needs to be connected in series, including direct device series connection (patent 200980162538.X ) or through modules connected in series (patent 20130051175.9), the number of modules connected in series is as high as dozens or even hundreds. A large number of IGBT units or modules need to be powered and meet insulation requirements. The DC series IGBT used in DC transmission can obtain energy from the IGBT terminal voltage in the off state (EP0868014B1), and the sub-modules in the modular multilevel converter (MMC) converter valve can also obtain energy from their own Capacitors gain energy because their sub-module capacitors maintain a certain voltage under normal operating conditions.

However, the IGBT units directly connected in series or cascaded sub-modules in the DC circuit breaker are in the conduction state for a long time during the normal operation of the circuit breaker, and there is no voltage in the capacitors of the sub-modules, so energy cannot be directly obtained from the sub-modules themselves. For the application of DC circuit breakers, Patent Document WO2011/095212 A2 discloses a technical solution for high-voltage insulation by laser energy delivery. However, the cost of laser energy delivery is high, especially when the IGBT unit or cascaded sub-modules have more functions, the energy required for energy supply is greater, which undoubtedly greatly increases the cost of the equipment.

Another way to obtain energy is to use a high-voltage insulating pulse transformer to deliver energy. Since each pulse transformer has to withstand high-voltage insulation greater than the DC bus voltage, the cost is also high.

Therefore, it is necessary to provide an energy harvesting device and its method, so as to obtain energy from the main branch of the DC circuit breaker and then supply power to a large number of series-connected sub-modules in the transfer branch.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a self-energy harvesting device for a high-voltage DC circuit breaker, the self-energy harvesting device is composed of a line energy harvesting unit, a high-frequency inverter circuit, a high-frequency transformer, and a magnetic ring transformer connected in sequence and a rectifier voltage regulator circuit.

Preferably, the line energy taking unit is composed of two bridge arms connected in parallel with a capacitor, the bridge arm is composed of a diode and a switch tube with an anti-parallel diode connected in series, and the connection between the diode and the switch tube The point is connected to the main branch of the high-voltage DC circuit breaker, and the two ends of the capacitor are connected to the high-frequency inverter circuit.

Preferably, the high-frequency inverter circuit takes the capacitor terminal of the line energy-taking unit as an input, and outputs high-frequency current to the high-frequency transformer.

Preferably, the primary side and the secondary side of the high-frequency transformer are respectively one winding and more than one winding.

Preferably, the primary side of the high-frequency transformer is connected to a high-frequency inverter circuit, and the output of the secondary side is connected to the magnetic ring transformer through a high-voltage cable.

Preferably, the self-energy harvesting device includes a full-bridge sub-module connected to the rectification and voltage stabilization circuit.

A method for realizing a self-energy harvesting device of a high-voltage direct current circuit breaker, the self-energy harvesting device is the above-mentioned self-energy harvesting device of a high-voltage direct current circuit breaker, and the realization method of the self-energy harvesting device includes the following steps:

S1, connecting the line energy harvesting unit in series to the main branch of the high-voltage direct current circuit breaker, and obtaining energy from the current of the main branch;

S2, when a current flows through the main branch, control the turn-on and turn-off of the switch tube;

S3, adjusting the charging time of the capacitor to control the voltage range of the capacitor.

Preferably, the voltage of the capacitor is smaller than the conduction voltage drop of the switch tube.

Compared with the closest prior art, the beneficial effects of the present invention are:

1. The energy harvesting device proposed by the present invention can obtain energy from the current of the main branch line, and provide power for driving the sub-module or IGBT unit of the transfer branch without needing another separate power supply.

2. In the energy harvesting device proposed by the present invention, the line energy harvesting unit and the high-frequency inverter use low-voltage switching devices, and the capacitors used for energy storage also use low-voltage capacitors, so the cost is relatively low.

3. When the energy harvesting device proposed by the present invention is used in a current limiting device composed of multiple DC circuit breakers in series, the insulation voltage of the high-frequency transformer is designed according to the withstand voltage requirements of the single DC circuit breaker where it is located. The high-frequency transformer power supply scheme reduces the insulation requirements of the high-frequency transformer.

Description of drawings

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

Fig. 1 is a schematic composition diagram of the self-energy harvesting device of the high-voltage DC circuit breaker of the present invention;

Fig. 2 is the main circuit diagram of the line energy taking unit in Fig. 1;

Fig. 3 is the main circuit diagram when the self-energy harvesting device of the high-voltage DC circuit breaker of the present invention is applied in the DC circuit breaker;

Fig. 4 is the main circuit diagram of the full bridge sub-module in Fig. 1;

5 is a wiring diagram of the present invention applied to a DC current limiting device composed of full bridge sub-modules;

Reference signs: 5-line energy-taking unit; 6-high-frequency transformer; 7-full-bridge sub-module; 8-magnetic ring transformer; 14-high-frequency inverter circuit; 15-rectification and voltage stabilization circuit.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

In order to thoroughly understand the embodiments of the present invention, the detailed structure will be set forth in the following description. Obviously, the practice of the embodiments of the invention is not limited to specific details familiar to those skilled in the art. Preferred embodiments of the present invention are described in detail below, however, the present invention may have other embodiments besides these detailed descriptions.

With reference to Fig. 1-Fig. 4, Fig. 1 is the composition schematic diagram of the self-energy harvesting device of high-voltage DC circuit breaker of the present invention; Fig. 2 is the main circuit diagram of line energy-capturing unit in Fig. 1; Fig. 3 is the self-contained energy of high-voltage direct current circuit breaker of the present invention The main circuit diagram of the energy harvesting device applied in the DC circuit breaker; Figure 4 is the main circuit diagram of the full bridge sub-module in Figure 1. The self-energy harvesting device described in Fig. 1 is composed of a line energy harvesting unit 5, a high-frequency inverter circuit 14, a high-frequency transformer 6, a magnetic ring transformer 8, a rectification and voltage stabilization circuit 15 and a full-bridge sub-module 7 connected in sequence.

As shown in Figure 2, currents in the positive and negative directions shown in 12 and 13 can flow. In the figure, the line energy-taking unit 5 is composed of two bridge arms connected in parallel with a capacitor C1, and one bridge arm is composed of T1, D1 and D3 One is formed in series, and the other is formed by connecting T2, D2 and D4 in series. D1 and D2 are the anti-parallel diodes of T1 and T2 respectively. The connection points of D1, D2, D3, D4 and T1 and T2 are connected to the main branch of the high-voltage DC circuit breaker, and the two ends of the capacitor C1 are connected to the high-frequency inverter circuit 14. The high-frequency inverter circuit 14 takes the capacitor C1 terminal of the line energy-taking unit 5 as an input, and outputs a high-frequency current to the high-frequency transformer 6; the high-frequency transformer 6 has a high-voltage insulation function, and the principle of the high-frequency transformer 6 is The side is a winding, the secondary side is a plurality of windings, the primary side is connected to the high-frequency inverter circuit 14, the output of the secondary side passes through a plurality of magnetic toroidal transformers 8 through high-voltage cables, and the secondary side of each magnetic toroidal transformer 8 and the transfer branch A sub-module or the rectification and voltage stabilization circuit in the IGBT unit is connected to supply power for the sub-module or IGBT unit.

A method for realizing a self-energy harvesting device of a high-voltage direct current circuit breaker, the self-energy harvesting device is the self-energy harvesting device of the above-mentioned high-voltage direct current circuit breaker, as shown in Figure 3, wherein 7 is a full-bridge sub-module, and 5 is the main The line energy harvesting unit of the self-energy harvesting device proposed by the invention. The line energy-taking unit 5 is connected in the main branch; the realization method of the self-energy-taking device comprises the following steps:

S1, connecting the line energy harvesting unit 5 in series to the main branch of the high-voltage DC circuit breaker, and obtaining energy from the current of the main branch;

S2, when the current flows in the main branch, control the on and off of T1 and T2;

S3, adjusting the charging time of the capacitor C1, so as to control the voltage of C1 within a certain range.

If the main branch flows through the current in the direction shown in 12 in Figure 2, when T1 and T2 are blocked, the main branch current flows through D1, C1, D4, and the capacitor C1 is charged; when T1 and T2 are turned on, the main branch Current flows through D1, T2 and capacitor C1 is bypassed. If the main branch flows through the current shown in Figure 2 in the direction of 13, when T1 and T2 are blocked, the main branch current flows through D2, C1, D3, and the capacitor C1 is charged; when T1 and T2 are turned on, the main branch Current flows through D1, T2 and capacitor C1 is bypassed. C1 delivers energy to the high frequency inverter circuit. The voltage across the sampling capacitor C1 is fed back to the hysteresis comparator, and the output is used to control the conduction and blocking of T1 and T2, which can control the voltage of C1 within a certain range. This range is set according to the normal working voltage range of the high frequency inverter circuit. Since C1 is connected in series to the main branch when the line energy-taking unit is locked, if the voltage of C1 is too high, it will cause the main branch to switch to the transfer branch. In order to prevent the line energy-taking unit from affecting the working state of the DC circuit breaker, the voltage of C1 should be smaller than the conduction voltage drop of the transfer branch sub-module or the IGBT unit. Therefore, the normal operating voltage range of the high-frequency inverter circuit is around tens of volts.

Since the line energy harvesting unit obtains energy from the current of the main branch, it is required that the current in the main branch of the circuit breaker is greater than a certain limit value. The module supplies power; when the main branch current is less than the current limit, the energy-taking device cannot work normally. The neutron module or IGBT unit of the main branch needs to be powered by other methods, such as optical power supply, or power supply from the ground potential by a high-frequency transformer. Since the number of main branch sub-modules or IGBT units is small, it will not have a great impact on the cost.

Since the operating voltage of the line energy-taking unit and the high-frequency inverter circuit is about tens of volts, the switching tubes in the high-frequency inverter circuit and the line energy-taking unit can use devices with lower voltages, and even use low-current on-state MOSFETs with lower impedance are used as power switches. Capacitors can also be relatively small in size. Since the voltage of the capacitor C1 is low, the stored energy is small, resulting in a high switching frequency of the switching tube of the line energy harvesting unit, but for low-voltage devices, it is not difficult to meet the switching frequency requirements.

When C1 selects a larger capacitance value, the switching frequency of the switching tube of the line energy harvesting unit can be reduced due to the large stored energy. For example, a supercapacitor bank with a capacitance of several farads can be used, which can effectively reduce the switching frequency.

When the energy harvesting device is applied to a DC current limiting device composed of full bridge sub-modules, as shown in FIG. 5 , FIG. 5 is a wiring diagram of the present invention applied to a DC current limiting device composed of full bridge sub modules. The main branch in each circuit breaker is equipped with a line energy-taking unit to supply power to the sub-module of the transfer branch of the circuit breaker. At this time, the high-frequency transformer only needs to meet the insulation withstand voltage requirements of the circuit breaker where it is located, that is, higher than the surge arrester the highest residual pressure. The energy harvesting device is also applicable to a DC circuit breaker composed of half-bridge modules or IGBT units connected in series.

The self-energy harvesting device proposed by the present invention is connected in series in the main branch of the DC circuit breaker, stores the current in the main branch in the energy storage capacitor, and then inverts it into a high-frequency current, which is transmitted through a high-frequency transformer and a pulse transformer To the submodule or IGBT unit of the DC circuit breaker, it supplies power for its drive and additional control circuits. The self-energy harvesting device utilizes the energy in the line and does not require a separate power supply. It is suitable for DC circuit breakers with a combination of mechanical switches and power electronic devices. When used in a current limiting device composed of multiple DC circuit breakers in series, The insulation voltage of the high-frequency transformer is designed according to the withstand voltage requirements of the single DC circuit breaker where it is located. Compared with the scheme of supplying power through the high-frequency transformer from the ground potential, the insulation requirements for the high-frequency transformer are reduced.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still implement the present invention Any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention is within the protection scope of the pending claims.

Claims (8)

1. a self-energy-capturing device of a high-voltage direct current circuit breaker, is characterized in that, described self-energy-capturing device consists of line energy-capturing unit (5), high-frequency inverter circuit (14), high-frequency transformer (6) connected successively ), a magnetic ring transformer (8) and a rectifying voltage stabilizing circuit (15) constitute. 2. The self-energy harvesting device of the high-voltage DC circuit breaker according to claim 1, characterized in that, the line energy harvesting unit (5) is composed of two bridge arms connected in parallel with a capacitor, and the bridge arms are composed of a diode and A switch tube with an anti-parallel diode is connected in series, the connection point of the diode and the switch tube is connected to the main branch of the high-voltage DC circuit breaker, and the two ends of the capacitor are connected to the high-frequency inverter circuit ( 14). 3. The self-energy harvesting device of the high-voltage DC circuit breaker according to claim 2, characterized in that, the high-frequency inverter circuit (14) takes the capacitor terminal of the line energy harvesting unit (5) as an input, and outputs a high-frequency current To the high frequency transformer (6). 4. The self-energy harvesting device of the high-voltage DC circuit breaker according to claim 3, characterized in that, the primary side and the secondary side of the high-frequency transformer (6) are respectively one winding and more than one winding. 5. The self-energy harvesting device of the high-voltage DC circuit breaker according to claim 4, wherein the primary side of the high-frequency transformer (6) is connected to the high-frequency inverter circuit (14), and the output of the secondary side is connected to the high-voltage cable through a high-voltage cable. To Toroidal Transformer (8). 6. The self-energy harvesting device of the high-voltage DC circuit breaker according to claim 4, characterized in that, the self-energy harvesting device comprises a full-bridge sub-module (7) connected to the rectification and voltage stabilization circuit (15). 7. A method for realizing a self-energy harvesting device of a high-voltage direct current circuit breaker, the self-energy harvesting device is the self-energy harvesting device of a high-voltage direct current circuit breaker according to any one of claims 1-6, wherein In that, the implementation method of the self-energy harvesting device includes the following steps: S1, connecting the line energy harvesting unit (5) in series to the main branch of the high-voltage DC circuit breaker, and obtaining energy from the current of the main branch; S2, when a current flows through the main branch, control the turn-on and turn-off of the switch tube; S3, adjusting the charging time of the capacitor to control the voltage range of the capacitor. 8 . The method for realizing the self-energy harvesting device according to claim 7 , wherein the voltage of the capacitor is smaller than the conduction voltage drop of the switch tube.