阅读说明：本技术 一种用于高压直流输电混合换流器的均压电路 (Voltage equalizing circuit for high-voltage direct-current transmission hybrid converter ) 是由 余占清 许超群 曾嵘 赵彪 陈政宇 于 2020-03-20 设计创作，主要内容包括：本发明公开了一种用于高压直流输电混合换流器的均压电路,所述均压电路包括可关断管和稳压电路,且所述可关断管与所述稳压电路连接。本发明的均压电路采用简单的电路拓扑结构,实现了所述新型高压直流输电混合换流器的桥臂的可关断管的电压均衡设计,从而在所述新型高压直流输电混合换流器正常运行和抵御换相失败故障时能够钳制电压过电压,保护好可关断管不受过电压损坏。(The invention discloses a voltage-sharing circuit for a high-voltage direct-current transmission hybrid converter, which comprises a turn-off tube and a voltage stabilizing circuit, wherein the turn-off tube is connected with the voltage stabilizing circuit. The voltage-sharing circuit adopts a simple circuit topological structure, and realizes the voltage balance design of the interruptible tube of the bridge arm of the novel high-voltage direct-current transmission hybrid converter, so that voltage overvoltage can be clamped when the novel high-voltage direct-current transmission hybrid converter is normally operated and a commutation failure fault is resisted, and the interruptible tube is well protected from being damaged by overvoltage.)

1. A voltage equalizing circuit for a high-voltage DC transmission hybrid converter is characterized in that,

the voltage-sharing circuit comprises a turn-off tube and a voltage-stabilizing circuit,

wherein the content of the first and second substances,

the tube capable of being cut off is connected with the voltage stabilizing circuit.

2. A voltage equalizing circuit for a HVDC hybrid converter according to claim 1,

the voltage stabilizing circuit comprises a metal oxide arrester MOV, one end of the metal oxide arrester MOV is connected to a first electrode of the interruptible tube, and the other end of the metal oxide arrester MOV is connected to a second electrode of the interruptible tube.

3. A voltage equalizing circuit for a HVDC hybrid converter according to claim 2,

the voltage stabilizing circuit further comprises a static voltage-sharing resistor R_pSaid static voltage equalizing resistor R_pConnected in parallel with the metal oxide arrester MOV.

4. A voltage equalizing circuit for a HVDC hybrid converter according to claim 3,

the voltage stabilizing circuit further comprises a buffer resistance-capacitance circuit,

the buffer resistance-capacitance circuit is connected with the metal oxide arrester MOV in parallel;

the buffer resistance-capacitance circuit comprises resistors R connected in series_sAnd a capacitor C_sSaid resistance R_sOne end of (A)A first electrode connected to the interruptible tube, the resistor R_sIs connected to the capacitor C at the other end_sOne terminal of said capacitor C_sIs connected to the second electrode of the interruptible tube.

5. A voltage equalizing circuit for a HVDC hybrid converter according to claim 1,

the voltage stabilizing circuit comprises a static voltage-sharing resistor R_pAnd a buffer circuit, the static voltage-sharing resistor R_pAnd the buffer circuit is connected in parallel.

6. A voltage equalizing circuit for a HVDC hybrid converter according to claim 5,

the snubber circuit includes a resistor R connected in series_sAnd a capacitor C_sSaid resistance R_sIs connected to the first electrode of the interruptible tube, the resistor R_sIs connected to the capacitor C at the other end_sOne terminal of said capacitor C_sIs connected to the second electrode of the interruptible tube.

7. A voltage equalizing circuit for a HVDC hybrid converter according to claim 5,

the buffer circuit comprises a metal oxide arrester MOV and a capacitor C which are connected in series_sOne end of the metal oxide arrester MOV is connected to the first electrode of the interruptible tube, and the other end of the metal oxide arrester MOV is connected to the capacitor C_sOne terminal of said capacitor C_sIs connected to the second electrode of the interruptible tube.

8. A voltage equalizing circuit for a HVDC hybrid converter according to claim 5,

the buffer circuit comprises a first voltage regulator tube,

the second electrode of the first voltage-stabilizing tube is connected to the first electrode of the turn-off tube, and the first electrode of the first voltage-stabilizing tube is connected to the second electrode of the turn-off tube.

9. A voltage grading circuit for a HVDC hybrid converter according to claim 8,

the buffer circuit further comprises a second voltage regulator tube,

the second voltage-stabilizing tube is connected with the first voltage-stabilizing tube in an inverse series connection way,

the first electrode of the second voltage-stabilizing tube is connected to the first electrode of the turn-off tube, the second electrode of the second voltage-stabilizing tube is connected to the second electrode of the first voltage-stabilizing tube, and the first electrode of the first voltage-stabilizing tube is connected to the second electrode of the turn-off tube.

10. A voltage grading circuit for a HVDC hybrid converter according to claim 8 or 9,

the first voltage-regulator tube and the second voltage-regulator tube are both diodes;

the first electrodes of the first voltage-stabilizing tube and the second voltage-stabilizing tube are anodes;

and the second electrodes of the first voltage-stabilizing tube and the second voltage-stabilizing tube are cathodes.

11. A voltage grading circuit for a HVDC hybrid converter according to any one of claims 1-9,

the turn-off tube is one or more of a gate turn-off thyristor, an integrated gate commutated thyristor, an insulated gate bipolar transistor, an enhanced gate transistor, a power field effect transistor or a diode,

when the turn-off transistor is a gate turn-off thyristor, an integrated gate commutated thyristor or a diode, the first electrode of the turn-off transistor is an anode, the second electrode of the turn-off transistor is a cathode,

when the turn-off transistor is an insulated gate bipolar transistor, an enhanced gate transistor, a power transistor or a power field effect transistor, the first electrode of the turn-off transistor is a collector electrode, and the second electrode of the turn-off transistor is an emitter electrode.

Technical Field

The invention belongs to the field of direct current transmission, and particularly relates to a voltage equalizing circuit for a high-voltage direct current transmission hybrid converter.

Background

The existing High-Voltage Direct Current (HVDC) transmission technology is widely applied at present due to the advantages of large transmission capacity, low loss, High reliability and the like. And the failure of commutation is one of the faults with higher occurrence probability of the direct current transmission system. In a converter used in a dc transmission system, a valve that is out of conduction fails to recover blocking capability for a period of time during which a reverse voltage is applied, or if a commutation process is not completed during the reverse voltage, the valve that is commutated will commutate to the valve that was originally scheduled to be out of conduction when the valve voltage changes to the forward direction, which is called commutation failure. The converter valve is locked, the power transmission channel of a direct current system is interrupted, and the power grid can be broken down in severe cases.

The traditional high-voltage direct-current transmission converter adopts three-phase bridge rectification formed by thyristors as a basic unit, each bridge arm is formed by a thyristor valve string, and the thyristor valve string can not actively control current to be switched off, so that the converter has larger current conversion current and reactive support, the risk of phase change failure exists, and the reliability needs to be improved.

Aiming at the fault problem of phase commutation failure existing in the existing high-voltage direct-current transmission converter, the novel high-voltage direct-current transmission hybrid converter is adopted, so that the capacity of the converter for resisting the phase commutation failure can be improved, and the frequency of the phase commutation failure is reduced.

The novel high-voltage direct-current transmission hybrid converter comprises a hybrid series connection of a thyristor and a turn-off pipe valve string, wherein the turn-off pipe valve in the turn-off pipe valve string can be one or more of improved turn-off devices such as an IGCT (integrated gate commutated thyristor) with reverse blocking capability, a GTO (gate turn-off thyristor) or an IGBT (insulated gate bipolar transistor), and the turn-off pipe valve can also be a series combination of an IGCT, a GTO or an IGBT turn-off device without reverse blocking capability and a diode. The novel high-voltage direct-current transmission hybrid converter is provided with a pipe valve string capable of being turned off, and a tube capable of being turned off in the pipe valve string capable of being turned off can face overvoltage when the novel high-voltage direct-current transmission hybrid converter is normally operated and a commutation failure fault is resisted, so that the problem of easy damage is solved.

Disclosure of Invention

In order to solve the problems, the invention provides a voltage equalizing circuit for a high-voltage direct-current power transmission hybrid converter for resisting commutation failure.

The voltage-sharing circuit for the high-voltage direct-current transmission hybrid converter comprises a turn-off tube and a voltage-stabilizing circuit,

wherein the content of the first and second substances,

the tube capable of being cut off is connected with the voltage stabilizing circuit.

Further, in the present invention,

the voltage stabilizing circuit comprises a metal oxide arrester MOV, one end of the metal oxide arrester MOV is connected to a first electrode of the interruptible tube, and the other end of the metal oxide arrester MOV is connected to a second electrode of the interruptible tube.

Further, in the present invention,

the voltage stabilizing circuit further comprises a static voltage-sharing resistor R_pSaid static voltage equalizing resistor R_pConnected in parallel with the metal oxide arrester MOV.

Further, in the present invention,

the voltage stabilizing circuit further comprises a buffer resistance-capacitance circuit,

the buffer resistance-capacitance circuit is connected with the metal oxide arrester MOV in parallel;

the buffer resistance-capacitance circuit comprises resistors R connected in series_sAnd a capacitor C_sSaid resistance R_sIs connected to the first electrode of the interruptible tube, the resistor R_sIs connected to the capacitor C at the other end_sOne terminal of said capacitor C_sIs connected to the second electrode of the interruptible tube.

Further, in the present invention,

the voltage stabilizing circuit comprises a static voltage-sharing resistor R_pAnd a buffer circuit, the static voltage-sharing resistor R_pAnd the buffer circuit is connected in parallel.

Further, in the present invention,

the snubber circuit includes a resistor R connected in series_sAnd a capacitor C_sSaid resistance R_sIs connected to the first electrode of the interruptible tube, the resistor R_sIs connected to the capacitor C at the other end_sOne terminal of said capacitor C_sIs connected to the second electrode of the interruptible tube.

Further, in the present invention,

the buffer circuit comprises a metal oxide arrester MOV and a capacitor C which are connected in series_sOne end of the metal oxide arrester MOV is connected to the first electrode of the interruptible tube, and the other end of the metal oxide arrester MOV is connected to the capacitor C_sOne terminal of said capacitor C_sIs connected to the second electrode of the interruptible tube.

Further, in the present invention,

the buffer circuit comprises a first voltage regulator tube,

the second electrode of the first voltage-stabilizing tube is connected to the first electrode of the turn-off tube, and the first electrode of the first voltage-stabilizing tube is connected to the second electrode of the turn-off tube.

Further, in the present invention,

the buffer circuit further comprises a second voltage regulator tube,

the second voltage-stabilizing tube is connected with the first voltage-stabilizing tube in an inverse series connection way,

the first electrode of the second voltage-stabilizing tube is connected to the first electrode of the turn-off tube, the second electrode of the second voltage-stabilizing tube is connected to the second electrode of the first voltage-stabilizing tube, and the first electrode of the first voltage-stabilizing tube is connected to the second electrode of the turn-off tube.

Further, in the present invention,

the first voltage-regulator tube and the second voltage-regulator tube are both diodes;

the first electrodes of the first voltage-stabilizing tube and the second voltage-stabilizing tube are anodes;

and the second electrodes of the first voltage-stabilizing tube and the second voltage-stabilizing tube are cathodes.

Further, in the present invention,

the turn-off tube is one or more of a gate turn-off thyristor, an integrated gate commutated thyristor, an insulated gate bipolar transistor, an enhanced gate transistor, a power field effect transistor or a diode,

when the turn-off transistor is a gate turn-off thyristor, an integrated gate commutated thyristor or a diode, the first electrode of the turn-off transistor is an anode, the second electrode of the turn-off transistor is a cathode,

when the turn-off transistor is an insulated gate bipolar transistor, an enhanced gate transistor, a power transistor or a power field effect transistor, the first electrode of the turn-off transistor is a collector electrode, and the second electrode of the turn-off transistor is an emitter electrode.

The voltage-sharing circuit adopts a simple circuit topological structure, and realizes the voltage balance design of the interruptible tube of the bridge arm of the novel high-voltage direct-current transmission hybrid converter, so that voltage overvoltage can be clamped when the novel high-voltage direct-current transmission hybrid converter is normally operated and a commutation failure fault is resisted, and the interruptible tube is well protected from being damaged by overvoltage.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 shows a topological structure diagram of a novel high voltage direct current transmission hybrid converter adopting the voltage-sharing circuit of the invention;

FIG. 2 shows a first equalizer circuit structure according to an embodiment of the invention;

FIG. 3 shows a second voltage equalizer circuit structure according to an embodiment of the invention;

FIG. 4 shows a third diagram of a voltage-sharing circuit according to an embodiment of the invention;

FIG. 5 shows a fourth voltage equalizer circuit structure according to an embodiment of the invention;

FIG. 6 shows a fifth diagram of a voltage grading circuit according to an embodiment of the invention;

FIG. 7 shows a sixth voltage grading circuit block diagram according to an embodiment of the invention;

fig. 8 shows a seventh configuration diagram of the voltage equalizing circuit according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 shows a topological structure diagram of a novel high-voltage direct-current transmission hybrid converter adopting the voltage-sharing circuit of the invention. As can be seen from fig. 1, the high-voltage dc transmission hybrid converter has 6 identical legs: ap, An, Bp, Bn, Cp, Cn; and points P and N are direct-current voltage connection points respectively, points P are positive electrodes, points N are negative electrodes, and points A, B and points C are connection points of the novel high-voltage direct-current power transmission hybrid converter and three-phase alternating current.

Wherein the content of the first and second substances,

each bridge arm is composed of a thyristor valve string and a turn-off thyristor valve string, and each thyristor valve string is composed of k thyristors (S)₁～S_k) Is composed of m disconnectable tubes (Q) connected in series, k is a positive integer greater than or equal to 1, and each disconnectable tube valve string is composed of m disconnectable tubes (Q)₁……Q_m) The components are connected in series, and m is a positive integer greater than or equal to 1; in each thyristor valve string, the anode of the previous thyristor is connected with the cathode of the next thyristor to realize series connection; the connection point of the thyristor valve string and the turn-off pipe valve string is T; the thyristor is a unidirectional thyristor, and the pipe valve string capable of being turned off can comprise one or more of IGCT or GTO or IGBT modified turn-off devices (in series) with reverse blocking capability, or IGCT or GTO or IGBT turn-off devices without reverse blocking capability and diodes in series combinationBlocking-capable IEGT (enhanced gate transistor), GTR (power transistor), MOSFET (power field effect transistor), etc. are combined in series with the diode.

Of the three first legs Ap, Bp and Cp of said legs, the thyristor S of the first end of the thyristor valve string₁The cathode of the thyristor is connected to the positive pole P of the direct voltage, and the thyristor S at the second end of the thyristor valve string_kIs connected to the connecting point T of the thyristor valve string and the turn-off pipe valve string;

in the three second arms An, Bn and Cn of the arms, the thyristor S at the first end of the thyristor valve string₁The cathodes of the thyristors in the series are connected to the three-phase AC connection points A, B and C, and the thyristors S at the second end of the series are connected to_kIs connected to the junction T of the thyristor valve string and the closable pipe valve string.

In order to resist the phase change failure, the novel high-voltage direct-current transmission hybrid converter needs to utilize a turn-off pipe valve string to perform turn-off operation during the phase change failure, so that the phase change current is forced to change the phase from a phase-changed bridge arm to a phase-change bridge arm. However, the series connection of the turn-off pipes of the turn-off pipe valve string is difficult, and the straight string realization difficulty is high.

Fig. 2 to 7 show 7 structures of the voltage equalizing circuit for the novel high-voltage direct-current transmission hybrid converter, wherein R is_pBeing static voltage-sharing resistors, R_sIs a resistance, C_sIs a capacitor, MOV is a metal oxide arrester, U_Z、U_Z1And U_Z2The high-voltage direct-current transmission hybrid converter is a voltage-stabilizing tube, and Q is a turn-off tube (an insulated gate bipolar transistor is adopted, a first electrode of the turn-off tube is a collector, and a second electrode of the turn-off tube is an emitter) in a turn-off tube valve string in the novel high-voltage direct-current transmission hybrid converter. The voltage regulator tube may be a diode.

The 7 configurations shown in fig. 2-7 all include a turn-off transistor Q and a regulator circuit connected to each other.

Fig. 2 shows a first structure of the voltage-sharing circuit of the present invention, in which the voltage-sharing circuit only includes a metal oxide arrester MOV, one end of the metal oxide arrester MOV is connected to the collector of the interruptible tube Q, and the other end of the metal oxide arrester MOV is connected to the emitter of the interruptible tube Q. The first structure of the voltage-sharing circuit adopts an arrester MOV to strictly limit the overvoltage on the turn-off pipe Q, so that the voltage-sharing effect is ensured.

Fig. 3 shows a second structure of the voltage-sharing circuit of the present invention, in which a voltage regulator circuit includes: static voltage-sharing resistor R_pAnd metal oxide arrester MOV, and static voltage-sharing resistor R_pIn parallel with the metal oxide arrester MOV. Static voltage-sharing resistor R_pOne end of the static voltage-sharing resistor R is connected to the collector of the turn-off tube Q_pIs connected to the emitter of said turn-off transistor Q. The second structure of the voltage-sharing circuit is based on the first structure and adopts a static voltage-sharing resistor R_pStatic voltage-sharing of the turn-off pipe Q is realized.

Fig. 4 shows a third structure of the voltage-sharing circuit of the present invention, in which a voltage regulator circuit includes: static voltage-sharing resistor R_pResistance R_sCapacitor C_sAnd a metal oxide arrester MOV. Static voltage-sharing resistor R_pOne end of the static voltage-sharing resistor R is connected to the collector of the turn-off tube Q_pIs connected to the emitter of the turn-off transistor Q, and a static voltage-sharing resistor R_pStatic voltage equalizing resistor R connected with metal oxide arrester MOV in parallel_pIs connected to a resistor R_sOne terminal of (1), resistance R_sIs connected to the capacitor C at the other end_sAnd a terminal of, and a capacitor C_sThe other end of the voltage-sharing resistor is connected to a static voltage-sharing resistor R_pThe other end of (a). Wherein, the resistance R_sAnd a capacitor C_sA buffer resistance-capacitance circuit and a static voltage-sharing resistor R connected in series_pAnd is connected with the buffer resistance-capacitance circuit in parallel. The third structure of the voltage-sharing circuit is connected with the R in parallel on the basis of the second structure_sAnd C_sThe buffer resistance-capacitance circuit is formed by connecting the switch-off tube Q in series, and can slow down the rising speed of voltage when the switch-off tube Q is switched off and reduce dynamic pressure difference.

Figure 5 shows the present inventionThe fourth structure of the voltage-sharing circuit of the invention is that the voltage-sharing circuit in the structure of the voltage-sharing circuit is composed of a static voltage-sharing resistor R_pAnd the buffer circuit is formed by connecting the buffer circuit in parallel, and the buffer circuit is the buffer resistance-capacitance circuit in the third structure. And compared with the third structure of the voltage equalizing circuit, the fourth structure of the voltage equalizing circuit is that the MOV is removed to form the metal oxide arrester. The fourth structure of the voltage-sharing circuit has the effects of realizing static voltage sharing on the turn-off pipe Q, slowing down the rising speed of the voltage when the turn-off pipe Q is turned off and reducing the dynamic voltage difference.

Fig. 6 shows a fifth structure of a voltage equalizing circuit according to the present invention, in which a voltage stabilizing circuit includes: static voltage-sharing resistor R_pMetal oxide arrester MOV and capacitor C_s. Static voltage-sharing resistor R_pOne end of the static voltage-sharing resistor R is connected to the collector of the turn-off tube Q_pIs connected to the emitter of the turn-off transistor Q, and a static voltage-sharing resistor R_pIs connected to one end of a metal oxide arrester MOV, and the other end of the metal oxide arrester MOV is connected to a capacitor C_sAnd a terminal of, and a capacitor C_sThe other end of the voltage-sharing resistor is connected to a static voltage-sharing resistor R_pThe other end of (a). The fifth structure of the voltage equalizing circuit is that the metal oxide arrester MOV replaces the resistor R in the fourth structure of the voltage equalizing circuit_sObtaining, i.e. metal oxide arrester MOV and capacitor C_sAre connected in series to form a buffer circuit. The fifth structure of the voltage equalizing circuit has the effects of realizing static voltage equalizing of the turnoff pipe Q and reducing the rising speed of the voltage of the turnoff pipe Q during turnoff, and reducing dynamic voltage difference, and simultaneously, the resistance R in the fourth structure of the voltage equalizing circuit is replaced by the MOV of the metal oxide arrester_sDue to metal oxide arrester MOV and capacitor C_sThe buffer circuit formed can not only delay the rising speed of the voltage of the turn-off tube Q when the turn-off tube Q is turned off, but also inhibit the oscillation process of the turn-off tube Q after the voltage rises to the rated value for the first time at the initial turn-off stage.

FIG. 7 shows a sixth structure of the voltage-sharing circuit of the present invention, in which the voltage-sharing circuit is composed of static voltage-sharing resistorsR_pAnd a voltage regulator tube U_ZAre connected in parallel, wherein a voltage stabilizing tube U_ZThe negative pole of the voltage regulator tube is connected to the collector of the turn-off tube Q, and the voltage regulator tube U_ZIs connected to the emitter of the turn-off transistor Q. Voltage stabilizing tube U_ZIndependently form a buffer circuit for stabilizing voltage, because the voltage stabilizing tube U_ZThe overvoltage and the clamping overvoltage can be strictly limited, so that the sixth structure of the voltage equalizing circuit has the effects of static voltage equalizing and strictly limiting the overvoltage and the clamping overvoltage for the turn-off tube Q.

FIG. 8 shows a seventh structure of the voltage-sharing circuit of the present invention, in which the voltage-sharing circuit is composed of a static voltage-sharing resistor R_pAnd a voltage regulator tube U_Z1And U_Z2Wherein a voltage regulator tube U_Z1The anode of the voltage regulator tube is connected to the collector of the turn-off tube Q, and the voltage regulator tube U_Z1Negative pole of the voltage regulator tube U_Z2Negative electrode of (1), stabilivolt U_Z2Is connected to the emitter of the turn-off transistor Q, and a static voltage-sharing resistor R_pAre connected to the collector and emitter of said turn-off transistor Q, respectively. Wherein, the voltage stabilizing tube U_Z1And U_Z2A buffer circuit for voltage stabilization is constructed. The seventh structure effect of the voltage-sharing circuit is the same as the sixth structure, namely the voltage-sharing circuit has the effects of static voltage sharing, strict overvoltage limiting and overvoltage clamping for the turn-off tube Q.

In conclusion, the voltage-sharing circuit can slow down the rising speed of the voltage of the turn-off pipe when the novel high-voltage direct-current transmission hybrid converter is turned off, reduce dynamic pressure difference, ensure voltage-sharing effect, realize overvoltage and overcurrent protection of the turn-off pipe under dynamic and static voltage-sharing and transient conditions, improve the reliability of the turn-off pipe, increase redundancy, and realize the voltage-balancing design of the turn-off pipe of the bridge arm of the novel high-voltage direct-current transmission hybrid converter, so that voltage overvoltage can be clamped when the novel high-voltage direct-current transmission hybrid converter is in normal operation and resists commutation failure faults, and the turn-off pipe is well protected from overvoltage damage.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.