WO2019119667A1 - 一种可变频率变压器故障穿越电路的控制方法及相关电路 - Google Patents

一种可变频率变压器故障穿越电路的控制方法及相关电路 Download PDF

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Publication number
WO2019119667A1
WO2019119667A1 PCT/CN2018/080591 CN2018080591W WO2019119667A1 WO 2019119667 A1 WO2019119667 A1 WO 2019119667A1 CN 2018080591 W CN2018080591 W CN 2018080591W WO 2019119667 A1 WO2019119667 A1 WO 2019119667A1
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Prior art keywords
voltage
grid
rotor
component
stator
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PCT/CN2018/080591
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English (en)
French (fr)
Inventor
陈思哲
卢嘉豪
张桂东
叶远茂
章云
张淼
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广东工业大学
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Priority to US16/252,636 priority Critical patent/US10938209B2/en
Publication of WO2019119667A1 publication Critical patent/WO2019119667A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/02—Circuit arrangements for ac mains or ac distribution networks using a single network for simultaneous distribution of power at different frequencies; using a single network for simultaneous distribution of ac power and of dc power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load

Definitions

  • the present application relates to the field of grid asynchronous interconnection technology, and in particular relates to a control method of a variable frequency transformer fault crossing circuit and a variable frequency transformer fault crossing circuit.
  • the power grid between different countries can share power resources.
  • the grids of different frequencies can be connected to each other through a variable frequency transformer.
  • Asynchronous interconnection of power grids with variable frequency transformers simple control, strong overload capability and no commutation failure, high reliability; no harmonics in use, better power quality; and stronger natural damping And inertial support ability, which is conducive to improving grid stability.
  • variable frequency transformer cannot block the propagation of the grid fault. For example, when a short circuit fault occurs on one side of the variable frequency transformer and the voltage drops, the other side of the grid will transmit a large number of short circuits to the faulty grid through the variable frequency transformer. The current will affect the safe operation of the grid on the fault-free side. Also, excessive short-circuit currents and three-phase asymmetrical currents can cause damage to the variable frequency transformer.
  • FIG. 1 is a schematic structural diagram of a prior art variable frequency transformer power grid fault traversing device according to the present application.
  • a series dynamic braking resistor is mainly used to prevent fault propagation.
  • all the series braking resistors are short-circuited by the bypass switch; when a voltage drop occurs on one side of the power grid, the corresponding bypass switch is disconnected according to the drop degree of the grid voltage, so that the series dynamic system
  • the dynamic resistance is connected to the power grid to suppress the abnormal increase of the current caused by the short circuit, improve the terminal voltage of the variable frequency transformer, and prevent the fault from spreading from the fault side power grid to the normal side power grid.
  • the purpose of the application is to provide a control method for a variable frequency transformer fault crossing circuit and a variable frequency transformer fault crossing circuit.
  • the compensation circuit is used for voltage compensation, thereby increasing the voltage and reducing the short circuit band.
  • a large amount of short-circuit current comes from, avoiding excessive power loss and preventing the voltage drop from falling to the other side of the grid.
  • the variable frequency transformer fault traversing circuit includes: a first power grid, a second power grid, a variable frequency transformer, a first compensation transformer and a first PWM converter; the first power grid is connected to a stator interface of the variable frequency transformer via a secondary coil of the first compensation transformer, and a primary coil of the first compensation transformer is connected in series Between the first output end and the second output end of the first PWM converter, the rotor interface of the variable frequency transformer is connected to the second power grid; the method includes:
  • the second grid voltage U g2abc of the variable frequency transformer interface voltage U sabc stator and rotor connection voltage U rabc pretreatment to obtain positive sequence voltage of the stator DC component U sdq+ , stator negative sequence voltage DC component U sdq- , rotor positive sequence voltage DC component U rdq+ and rotor negative sequence voltage DC component U rdq- ;
  • the voltage frequency f g1 of a power grid and the voltage frequency f g2 of the second power grid are subjected to a reference voltage calculation process to obtain a voltage reference value U t1dq+ and a voltage reference value U t1dq ⁇ of the first PWM converter;
  • Control signal acquisition processing is performed on the voltage reference value U t1dq+ and the voltage reference value U t1dq ⁇ to obtain switching signals S a , S b , and S c that control the first PWM converter.
  • the stator positive sequence voltage DC component U sdq+ , the stator negative sequence voltage DC component U sdq ⁇ , the rotor positive sequence voltage DC component U rdq+ , and the rotor negative sequence voltage DC component U rdq ⁇ include:
  • the first grid voltage U g1abc , the second grid voltage U g2abc , the stator interface voltage U sabc and the rotor interface voltage U rabc are respectively processed by three-phase static two-phase stationary coordinate transformation to obtain two phases.
  • the first grid voltage integrated vector U g1 ⁇ and the second grid voltage integrated vector U g2 ⁇ are respectively separated by a positive and negative sequence signal to obtain a first grid positive sequence voltage vector U g1 ⁇ + in a two-phase stationary coordinate system.
  • the first grid positive sequence voltage vector U g1 ⁇ + , the first grid negative sequence voltage vector U g1 ⁇ , the second grid positive sequence voltage vector U g2 ⁇ +, and the second grid negative sequence voltage vector U G2 ⁇ - is respectively processed by the phase angle to obtain the first grid positive sequence voltage phase ⁇ g1+ , the first grid negative sequence voltage phase ⁇ g1 , the second grid positive sequence voltage phase ⁇ g2+ , and the second grid negative sequence voltage phase ⁇ g2 - ;
  • stator voltage integrated vector U s ⁇ and the rotor voltage integrated vector U r ⁇ are respectively separated by a positive and negative sequence signal to obtain a stator positive sequence voltage vector U s ⁇ + and a stator negative sequence voltage vector U in a two-phase stationary coordinate system.
  • stator positive sequence voltage vector U s ⁇ + , the stator negative sequence voltage vector U s ⁇ , the rotor positive sequence voltage vector U r ⁇ + and the rotor negative sequence voltage vector U r ⁇ respectively pass through two phases Static to two-phase rotating coordinate transformation processing, the stator positive sequence voltage DC component U sdq+ , stator negative sequence voltage DC component U sdq- , rotor positive sequence voltage DC component U rdq+ and rotor negative sequence voltage DC component in synchronous rotating coordinate system are obtained .
  • U rdq- The obtained stator positive sequence voltage vector U s ⁇ + , the stator negative sequence voltage vector U s ⁇ , the rotor positive sequence voltage vector U r ⁇ + and the rotor negative sequence voltage vector U r ⁇ respectively pass through two phases Static to two-phase rotating coordinate transformation processing, the stator positive sequence voltage DC component U sdq+ , stator negative sequence voltage DC component U sdq- , rotor positive sequence voltage DC component U rdq
  • stator positive sequence voltage DC component U sdq+ , the stator negative sequence voltage DC component U sdq ⁇ , the rotor positive sequence voltage DC component U rdq+ , the rotor negative sequence voltage DC component U rdq ⁇ , the first A grid voltage frequency f g1 and the second grid voltage frequency f g2 are processed according to a first preset voltage control equation to obtain a voltage reference value U t1dq+ and a voltage reference value U t1dq ⁇ of the first PWM converter;
  • the first preset voltage control equations are as follows:
  • the K p3 and the K i3 are respectively a proportional coefficient and an integral coefficient of the first PWM converter positive sequence voltage PI regulator, and the K p4 and the K i4 are respectively the first PWM converter negative The proportional coefficient and integral coefficient of the sequence voltage PI regulator.
  • control signal acquisition process is performed on the voltage reference value U t1dq+ and the voltage reference value U t1dq ⁇ , and the switch signals S a , S b , and S c that are used to control the first PWM converter are obtained.
  • switch signals S a , S b , and S c that are used to control the first PWM converter are obtained. Specifically include:
  • the voltage reference signal U t1 ⁇ + and the voltage reference signal U t1 ⁇ are respectively added to obtain a voltage reference signal U t1 ⁇ of the first PWM converter in a two-phase stationary coordinate system;
  • the voltage reference signal U t1 ⁇ is passed through a space vector pulse width modulation module to obtain switching signals S a , S b , and S c that control the first PWM converter.
  • variable frequency transformer fault traversing circuit further includes: a second compensation transformer and a second PWM converter; a secondary coil of the second compensation transformer is connected in series to the second power grid and the variable Between the rotor interfaces of the frequency transformer, the primary winding of the second compensation transformer is connected in series between the first input end and the second output end of the PWM converter.
  • the method further includes:
  • stator positive sequence voltage DC component U sdq+ , the stator negative sequence voltage DC component U sdq ⁇ , the rotor positive sequence voltage DC component U rdq+ , the rotor negative sequence voltage DC component U rdq ⁇ , the first a grid voltage frequency f g1 and the second grid voltage frequency f g2 are subjected to a reference voltage calculation process to obtain a voltage reference value U t2dq+ and a voltage reference value U t2dq ⁇ of the second PWM converter;
  • Control signal acquisition processing is performed on the voltage reference value U t2dq+ and the voltage reference value U t2dq ⁇ to obtain switching signals S a , S b , and S c that control the second PWM converter.
  • stator positive sequence voltage DC component U sdq+ , the stator negative sequence voltage DC component U sdq ⁇ , the rotor positive sequence voltage DC component U rdq+ , and the rotor negative sequence voltage DC component U Rdq- , the first grid voltage frequency f g1 and the second grid voltage frequency f g2 reference voltage calculation process, obtaining a voltage reference value U t2dq+ and a voltage reference value U t2dq- of the second PWM converter, include:
  • stator positive sequence voltage DC component U sdq+ , the stator negative sequence voltage DC component U sdq ⁇ , the rotor positive sequence voltage DC component U rdq+ , the rotor negative sequence voltage DC component U rdq ⁇ , the first A grid voltage frequency f g1 and the second grid voltage frequency f g2 are processed according to a second preset voltage control equation to obtain a voltage reference value U t2dq+ and a voltage reference value U t2dq- of the second PWM converter;
  • the second preset voltage control equations are as follows:
  • K p5 and the K i5 are respectively a proportional coefficient and an integral coefficient of the second PWM converter positive sequence voltage PI regulator
  • the K p6 and the K i6 are respectively the second PWM converter negative
  • control signal acquisition process is performed on the voltage reference value U t2dq+ and the voltage reference value U t2dq ⁇ , and the switch signals S a , S b , and S c that are used to control the second PWM converter are obtained, specifically including :
  • the voltage reference signal U t2 ⁇ + and the voltage reference signal U t2 ⁇ are respectively added to obtain a voltage reference signal U t2 ⁇ of the second PWM converter in a two-phase stationary coordinate system;
  • the voltage reference signal U t2 ⁇ is passed through a space vector pulse width modulation module to obtain switching signals S a , S b , and S c that control the second PWM converter.
  • a variable frequency transformer fault traversing circuit includes a first power grid (1), a second power grid (2), a variable frequency transformer (3), a first three-phase rectifier (6), and a motor drive. a converter (4), a first compensation circuit (5), and a control circuit (7);
  • the first power grid (1) is connected to an input end of the first three-phase rectifier (6) and a first output end of the first compensation circuit (5);
  • the second output end of the first compensation circuit (5) is connected to the stator interface (31) of the variable frequency transformer (3);
  • An output end of the first three-phase rectifier (6) is connected to an input end of the first compensation circuit (5) and an input end of the motor drive converter (4);
  • the motor drive converter (4) is coupled to a drive motor of the variable frequency transformer (3);
  • a rotor interface (32) of the variable frequency transformer (3) is connected to the second power grid (2);
  • the control circuit (7) is connected to a control signal input terminal of the first compensation circuit (5).
  • the first compensation circuit (5) includes: a first compensation transformer (51) and a first PWM converter (52);
  • a secondary coil of the first compensation transformer (51) is connected in series between the first grid (1) and a stator interface (31) of the variable frequency transformer (3);
  • An output end of the first PWM converter (52) is connected to an input end of the first compensation transformer (51); an input end of the first PWM converter (52) and the first compensation circuit (5)
  • the input terminal of the first PWM converter (52) is connected to the control signal input terminal of the first compensation circuit (5).
  • the input end of the first compensation circuit (5) is connected to the first capacitor.
  • the method further includes: a second three-phase rectifier (8) and a second compensation circuit (9);
  • the second output end of the second compensation circuit (9) is connected to the rotor interface (32) of the variable frequency transformer (3);
  • An output end of the second three-phase rectifier (8) is connected to an input end of the second compensation circuit (9) and an output end of the first three-phase rectifier (6);
  • the control signal input terminal of the second compensation circuit (9) is connected to the control circuit (7).
  • the second compensation circuit (9) includes: a second compensation transformer (91) and a second PWM converter (92);
  • a secondary coil of the second compensation transformer (91) is connected in series between the second grid (2) and a rotor interface (32) of the variable frequency transformer (3); the second compensation transformer (91) a primary coil is connected in series between the first input and the second input of the second PWM converter (92);
  • An input end of the second PWM converter (92) is connected to an input end of the second compensation circuit (9);
  • the control signal input end of the second PWM converter (92) is connected to the control signal input end of the second compensation circuit (9).
  • the input end of the second compensation circuit (9) is connected to the second capacitor.
  • the variable frequency transformer By voltage compensation when the grid voltage drop occurs, the voltage can be increased, the short circuit current caused by the short circuit can be reduced, excessive power loss can be avoided, and the voltage drop fault can be prevented from falling to the other side of the grid.
  • the variable frequency transformer when the grid voltage is asymmetrically dropped, the variable frequency transformer generates torque ripple, prolongs the life of the mechanical components, and avoids noise pollution.
  • the present application also provides a variable frequency transformer fault traversing circuit, which has the above-mentioned beneficial effects, and will not be described herein.
  • FIG. 1 is a schematic structural diagram of a prior art variable frequency transformer power grid fault traversing device according to the present application
  • FIG. 2 is a schematic structural diagram of a variable frequency transformer fault traversing circuit according to an embodiment of the present disclosure
  • FIG. 3 is a schematic structural diagram of a compensation circuit in a variable frequency transformer fault traversing circuit according to an embodiment of the present application
  • variable frequency transformer fault traversing circuit according to an embodiment of the present disclosure
  • FIG. 5 is a flowchart of a method for controlling a variable frequency transformer fault traversing circuit according to an embodiment of the present disclosure
  • FIG. 6 is a control block diagram of a control method for a variable frequency transformer fault traversing circuit according to an embodiment of the present application
  • FIG. 7 is a control block diagram of another control method for a variable frequency transformer fault traversing circuit according to an embodiment of the present application.
  • 1 is the first power grid
  • 2 is the second power grid
  • 3 is the variable frequency transformer
  • 31 is the stator interface
  • 32 is the rotor interface
  • 4 is the motor drive converter
  • 5 is the first compensation circuit
  • 51 is the first compensation transformer
  • 52 is the first PWM converter
  • 6 is the first three-phase rectifier
  • 7 is the control circuit
  • 8 is the second three-phase rectifier
  • 9 is the second compensation circuit
  • 91 is the second compensation transformer
  • 92 is the second PWM converter .
  • the core of the embodiment of the present application is to provide a variable frequency transformer fault crossing circuit and a control method thereof.
  • a compensation circuit is used for voltage compensation, thereby increasing the voltage and reducing a large amount of short circuit current caused by the short circuit. To avoid excessive power loss and prevent the voltage drop from falling to the other side of the grid.
  • FIG. 2 is a schematic structural diagram of a variable frequency transformer fault traversing circuit according to an embodiment of the present application.
  • the embodiment provides a variable frequency transformer fault traversing circuit, which can improve the circuit voltage to reduce the short circuit current by compensating the reactive power, and prevent the voltage drop fault from falling to the other side of the power grid.
  • the variable frequency transformer fault traverses the circuit and can
  • the system includes: a first power grid 1, a second power grid 2, a variable frequency transformer 3, a first three-phase rectifier 6, a motor drive converter 4, a first compensation circuit 5, and a control circuit 7;
  • the first power grid 1 is connected to the input end of the first three-phase rectifier 6 and the first output end of the first compensation circuit 5;
  • the second output of the first compensation circuit 5 is connected to the stator interface 31 of the variable frequency transformer 3;
  • An output end of the first three-phase rectifier 6 is connected to an input end of the first compensation circuit 5 and an input end of the motor drive converter 4;
  • An output end of the motor drive converter 4 is connected to a drive motor of the variable frequency transformer 3;
  • the rotor interface 32 of the variable frequency transformer 3 is connected to the second power grid 2;
  • the control circuit 7 is connected to the control signal input of the first compensation circuit 5.
  • the circuit of this embodiment mainly obtains DC power through the first three-phase rectifier 6, and supplies the motor to drive the converter 4 so that the variable frequency transformer 3 can operate normally.
  • circuit failures are inevitable, and circuit short circuit is a common circuit failure.
  • a short circuit occurs on one side of the power grid, it will cause a voltage drop, that is, the voltage of the power grid on one side will decrease rapidly, and the power grid on the other side will be forced to transmit a large amount of short-circuit current to the fault side through the variable frequency transformer, which will affect the faultlessness.
  • the safe operation of the side grid, while excessive short-circuit current can also cause damage to the variable frequency transformer. Therefore, it is necessary to suppress the voltage drop on the fault side and prevent the fault from traversing to the other side of the grid.
  • an automatic control device will be built in the power grid.
  • the load is connected to the grid through the automatic control device, the short-circuit current is suppressed, and the extreme of the variable frequency transformer is increased.
  • the voltage is thus prevented from spreading from the fault side to the normal side grid.
  • the way of connecting to the load is limited by the physical limitation of the resistor, and the limiting effect on the short-circuit current is limited, and a large amount of power consumption wastes a large amount of energy on the resistor.
  • the first compensation circuit 5 provided in this embodiment can perform voltage compensation on the first power grid 1 through a control signal and a compensation circuit of the control circuit.
  • the voltage of the first power grid 1 side can be increased by voltage compensation, and further, a large amount of short circuit current caused by the short circuit can be reduced.
  • the voltage compensation can be implemented by reactive power compensation.
  • Reactive power compensation full name reactive power compensation, is a technology that improves the power factor of the power grid in the power supply system, reduces the loss of the power supply transformer and the transmission line, improves the power supply efficiency, and improves the power supply environment.
  • Implementing reactive power compensation in the circuit will increase the power factor of the circuit. At the same time, it can also increase the system voltage, reduce the consumption of transformers and lines, and improve the load capacity of transformers and lines.
  • part of the reactive current consumed in the circuit no longer needs to be absorbed from the system, so that the voltage drop of the compensation circuit is reduced, so the voltage is increased, and the current can be reduced, which causes the loss of the line and the transformer. Reduced; part of the reactive current is not absorbed from the system, so that the line and transformer can transmit more active energy, which improves the load capacity of the equipment.
  • the embodiment provides a voltage compensation circuit, which can perform voltage compensation when a grid voltage drop fault occurs in the compensation circuit, thereby increasing the voltage, reducing a large amount of short-circuit current caused by the short circuit, and avoiding excessive power loss. To prevent the voltage drop from falling to the other side of the grid.
  • the circuit in this embodiment is a contralateral circuit, that is, the first power grid 1 and the second power grid 2, but only the first compensation circuit 5 is installed in the first power grid 1, that is, only one side can be prevented. The voltage drops through the fault.
  • FIG. 3 is a schematic structural diagram of a compensation circuit in a variable frequency transformer fault traversing circuit according to an embodiment of the present application.
  • this embodiment is intended to provide a specific description of the compensation circuit in the previous embodiment.
  • the other parts are substantially the same as the previous embodiment. For the same part, reference may be made to the previous embodiment, and details are not described herein again.
  • the first compensation circuit 5 may specifically include: a first compensation transformer 51 and a first PWM converter 52;
  • the secondary winding of the first compensation transformer 51 is connected in series between the first grid 1 and the stator interface 31 of the variable frequency transformer 3; the primary winding of the first compensation transformer 51 is connected in series at the first output of the first PWM converter 52 and Between the second outputs;
  • the output of the first PWM converter 52 is connected to the input of the first compensation transformer 51; the input of the first PWM converter 52 is connected to the input of the first compensation circuit 5; the control signal input of the first PWM converter 52 The terminal is connected to the control signal input terminal of the first compensation circuit 5.
  • the first PWM converter 52 can output a corresponding current by receiving the control signal of the control circuit 7, and is compensated into the grid circuit by the first compensation transformer 51.
  • the first PWM converter 52 can rectify the direct current to a corresponding three-phase alternating current by receiving a switching signal of the control circuit 7, and therefore, the PWM converter can also be a PWM rectifier.
  • the control circuit 7 is mainly an algorithm for executing a corresponding control signal to obtain a corresponding control signal. Therefore, the control circuit 7 can be a DSP control board, an embedded control board, or a single chip microcomputer.
  • the general control circuit 7 is a weak current circuit that supplies only control signals to the PWM converter.
  • the algorithm in the control circuit 7 can modify the algorithm accordingly according to the needs of the actual application environment, which is not limited herein.
  • the input end of the first compensation circuit 5 is grounded through the first capacitor.
  • FIG. 4 is a schematic structural diagram of another variable frequency transformer fault traversing circuit according to an embodiment of the present application.
  • the first voltage compensation circuit provided by the embodiment of the present application is one-sided compensation, and cannot solve the voltage drop problem on the other side. Therefore, based on the first voltage compensation circuit embodiment, the present implementation is directed to the voltage drop problem occurring on both sides.
  • the other parts are substantially the same as the previous embodiment. For the same part, refer to the previous embodiment, and no further details are provided herein.
  • variable frequency transformer fault traversing circuit may further include: a second three-phase rectifier 8 and a second compensation circuit 9;
  • the second power grid 2 is connected to the input end of the second three-phase rectifier 8 and the first output end of the second compensation circuit 9;
  • the second output of the second compensation circuit 9 is connected to the rotor interface 32 of the variable frequency transformer 3;
  • An output end of the second three-phase rectifier 8 is connected to an input end of the second compensation circuit 9 and an output end of the first three-phase rectifier 6;
  • the control signal input terminal of the second compensation circuit 9 is connected to the control circuit 7.
  • the second compensation circuit 9 may include: a second compensation transformer 91 and a second PWM converter 92;
  • the secondary winding of the second compensation transformer 91 is connected in series between the second grid 2 and the rotor interface 32 of the variable frequency transformer 3; the primary winding of the second compensation transformer 91 is connected in series at the first input of the second PWM converter 92 and Between the second outputs;
  • the input terminal of the second PWM converter 92 is connected to the input terminal of the second compensation circuit 9; the control signal input terminal of the second PWM converter 92 is connected to the control signal input terminal of the second compensation circuit 9.
  • the second three-phase rectifier 8 is used to change the circuit structure into a symmetrical structure, and then the second compensation circuit 9 is connected in the second power grid 2 and the direct current circuit, and the whole circuit forms a symmetrical structure, which can solve the voltage drop failure on the other side. problem.
  • the second compensation circuit 9 also needs the control circuit 7 to perform control, the algorithm in the control circuit 7 needs to be adaptively changed, but the algorithm of the control signal is substantially the same as the above, and details are not described herein.
  • the input end of the second compensation circuit 9 is grounded through the second capacitor.
  • the embodiment of the present application provides a voltage compensation circuit, which can perform voltage compensation when a grid voltage drop fault occurs in the compensation circuit, thereby increasing the voltage, reducing a large amount of short-circuit current caused by the short circuit, and avoiding excessive power loss. Prevent voltage drop faults from falling to the other side of the grid.
  • variable frequency transformer fault traversing circuit provided by the above embodiment, a control method of the variable frequency transformer fault traversing circuit provided by the embodiment of the present application is introduced below.
  • a control method of a variable frequency transformer fault ride-through circuit described below and a variable frequency transformer fault ride-through circuit described above may be referred to each other.
  • FIG. 5 is a flowchart of a method for controlling a variable frequency transformer fault traversing circuit according to an embodiment of the present application.
  • the present embodiment provides a control method for a variable frequency transformer fault traversing circuit, which can prevent a fault voltage from crossing a variable frequency transformer, and is applied to the variable frequency transformer fault traversing circuit provided by any of the above embodiments, which will be described below with reference to FIG. 2 .
  • the embodiment provides a control method for a variable frequency transformer fault traversing circuit, which may include:
  • the voltage U g1abc of the first power grid and the voltage U g2abc of the second power grid are processed by the digital phase locked loop to obtain the voltage frequency f g1 of the first power grid and the frequency f g2 of the second power grid voltage;
  • the embodiment of the present application may also provide another control method of the variable frequency transformer fault traversing circuit, which is applied to the variable frequency transformer fault traversing circuit shown in FIG. 3 or FIG. 4.
  • the S103 may further include: a stator positive sequence voltage DC component U sdq+ , a stator negative sequence voltage DC component U sdq ⁇ , a rotor positive sequence voltage DC component U rdq+ , a rotor negative sequence voltage DC component U rdq ⁇ , a first power grid voltage frequency f g1 f g2 of the second frequency and the grid voltage is the reference voltage calculation processing, to obtain a first PWM converter voltage reference U t1dq +, U t1dq- voltage reference and a second PWM converter voltage reference U T2dq+ , voltage reference value U t2dq- ;
  • the method further includes: performing control signal acquisition processing on the voltage reference value U t1dq+ , the voltage reference value U t1dq ⁇ , the voltage reference value U t2dq+ , and the voltage reference value U t2dq ⁇ to obtain a switch signal S for controlling the first PWM converter. a , S b , S c and switching signals S a2 , S b2 , S c2 for controlling the second PWM converter.
  • variable frequency transformer During the operation of the variable frequency transformer, there may be a fault in the grid voltage on one side of the variable frequency transformer, causing the current flowing through the variable frequency transformer to be asymmetrical, further causing twice the grid frequency torque. Fluctuation will shorten the life of mechanical equipment.
  • the series-compensated PWM converter can achieve complete compensation of the voltage across the variable frequency transformer by adopting voltage closed-loop control, and eliminate the torque ripple caused by the grid voltage asymmetry fault.
  • the control method described above is a voltage closed-loop control method for the series-compensated PWM converter.
  • the preprocessing refers to obtaining the processing of the positive and negative sequence DC voltage components of the variable frequency transformer stator and the rotor, and also obtaining the voltage frequency of the first power grid and the voltage frequency of the second power grid through the digital phase locked loop.
  • the voltage calculation process is mainly based on the voltage control equation to calculate the voltage reference value.
  • the specific voltage control method can be set according to the specific application environment, and will not be described here.
  • a control signal for controlling the switching control of the converter can be obtained, and then the series-compensated PWM converter is controlled to perform correlation transformation to obtain a compensation voltage for the control circuit to compensate.
  • FIG. 6 is a control block diagram of a control method for a variable frequency transformer fault crossing circuit according to an embodiment of the present application.
  • this embodiment may provide a control method for a variable frequency transformer fault traversing circuit, which may include:
  • the first grid voltage integrated vector U g1 ⁇ and the second grid voltage integrated vector U g2 ⁇ are respectively separated by the positive and negative sequence signals to obtain the first grid positive sequence voltage vector U g1 ⁇ + in the two-phase stationary coordinate system,
  • the voltage vector U g1 ⁇ , the second grid positive sequence voltage vector U g2 ⁇ + and the second grid negative sequence voltage vector U g2 ⁇ are respectively processed through the phase angle to obtain the first grid positive sequence voltage phase ⁇ g1+ , the first grid negative sequence Voltage phase ⁇ g1- , second grid positive sequence voltage phase ⁇ g2+ and second grid negative sequence voltage phase ⁇ g2- ;
  • stator positive sequence voltage vector U s ⁇ + , the stator negative sequence voltage vector U s ⁇ , the rotor positive sequence voltage vector U r ⁇ + and the rotor negative sequence voltage vector U r ⁇ respectively pass two phases of stationary to two phase rotation
  • the coordinate transformation process is used to obtain the stator positive sequence voltage DC component U sdq+ , the stator negative sequence voltage DC component U sdq- , the rotor positive sequence voltage DC component U rdq+ and the rotor negative sequence voltage DC component U rdq- in the synchronous rotating coordinate system.
  • the first preset voltage control equation and the second preset voltage control equation are respectively as follows:
  • K p3 and K i3 are the proportional and integral coefficients of the positive PWM voltage regulator of the first PWM converter, respectively, and K p4 and K i4 are the proportional coefficients and integrals of the negative PWM voltage regulator of the first PWM converter, respectively.
  • the coefficients, K p5 and K i5 are the proportional and integral coefficients of the positive PWM voltage regulator of the second PWM converter, respectively, and K p6 and K i6 are the proportional coefficients and integrals of the negative PWM voltage regulator of the second PWM converter, respectively. coefficient;
  • the voltage reference value U t1dq+ , the voltage reference value U t1dq ⁇ , the voltage reference value U t2dq+ , and the voltage reference value U t2dq ⁇ are rotated into two-phase stationary coordinate transformation processing to obtain the two-phase stationary coordinate system.
  • the voltage reference signal U t1 ⁇ + , the voltage reference signal U t1 ⁇ , the voltage reference signal U t2 ⁇ + , and the voltage reference signal U t2 ⁇ are respectively added to obtain the voltage of the first PWM converter in the two-phase stationary coordinate system.
  • a reference signal U t1 ⁇ and a voltage reference signal U t2 ⁇ of the second PWM converter are respectively added to obtain the voltage of the first PWM converter in the two-phase stationary coordinate system.
  • the control signal generated by the above steps can enable the compensation circuit to completely compensate the voltage across the variable frequency transformer when the grid voltage is asymmetrically faulty, and eliminate the variable frequency transformer torque fluctuation caused by the grid voltage asymmetry fault.
  • the embodiment of the present application can also provide another control method of the variable frequency transformer fault crossing circuit.
  • FIG. 7 is a control block diagram of another control method for a variable frequency transformer fault traversing circuit according to an embodiment of the present application.
  • the present embodiment provides a control signal generating method for another compensation circuit.
  • the second embodiment is applied to generate a corresponding control signal.
  • the method may include:
  • stator and rotor voltage vectors U s ⁇ and U r ⁇ are respectively subjected to two-phase stationary/synchronous rotation coordinate transformation module to obtain the rotor voltage DC components U sdq and U rdq in the synchronous rotating coordinate system;
  • K p1 and K i1 are the proportional and integral coefficients of the series-compensated PWM converter 1 voltage PI regulator, respectively, and K p2 and K i2 are the proportional and integral coefficients of the series-compensated PWM converter 2 voltage PI regulator, respectively;
  • the voltage reference values U t1dq and U t2dq of the series compensation PWM converter 1 and the series compensation PWM converter 2 are respectively passed through a synchronous rotation/two-phase stationary coordinate transformation module to obtain a series compensation PWM in a two-phase stationary coordinate system.
  • the voltage reference signals U t1 ⁇ , U t2 ⁇ of the series compensation PWM converter 1 and the series compensation PWM converter 2 are respectively passed through a space vector pulse width modulation module, and respectively modulated to obtain a control series compensation PWM converter 1 and series compensation.
  • the grid 1 and the grid 2 are the first grid 1 and the second grid 2 in the above embodiment, and the series compensation PWM converter 1 and the series compensation PWM converter 2 are the first PWM converter 52 in the above embodiment. And a second PWM converter 92.
  • the control signals of the two compensation circuits have a symmetrical relationship to some extent, so a pair of control signals can be calculated according to the same preset control equation. That is, the control signals of the first compensation circuit and the second compensation circuit.
  • the control signal obtained in this embodiment can control the PWM converter and the compensation transformer in the compensation circuit to perform voltage compensation, increase the corresponding system voltage, reduce the corresponding current, and avoid the fault crossing to another Side grid.
  • the steps of a method or algorithm described in connection with the embodiments disclosed herein can be implemented directly in hardware, a software module executed by a processor, or a combination of both.
  • the software module can be placed in random access memory (RAM), memory, read only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or technical field. Any other form of storage medium known.
  • variable frequency transformer fault crossing circuit and the variable frequency transformer fault crossing circuit provided by the present application are described in detail above.
  • the principles and implementations of the present application have been described in the context of specific examples, and the description of the above embodiments is only to assist in understanding the method of the present application and its core idea. It should be noted that those skilled in the art can make several modifications and changes to the present application without departing from the spirit and scope of the invention.

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Abstract

本申请公开了一种可变频率变压器故障穿越电路及其控制方法，包括：对采集的电网电压、定子接口电压以及转子接口电压进行预处理得到定子电压直流分量和转子电压直流分量，并通过数字锁相环检测处理得到第一电网电压频率和第二电网电压频率；将定子电压直流分量、转子电压直流分量、第一电网电压频率以及第二电网电压频率进行参考电压计算处理，得到第一PWM变换器的电压参考值与第二PWM变换器的电压参考值；对电压参考值进行控制信号获取处理，得到控制第一PWM变换器和第二PWM变换器的开关信号。通过当发生电网电压不对称故障时，进行电压补偿，解决电网电压不对称故障，防止电压不对称故障继续蔓延。

Description

一种可变频率变压器故障穿越电路的控制方法及相关电路
本申请要求于2017年12月21日提交中国专利局、申请号为201711364222.1、发明名称为“一种可变频率变压器故障穿越电路的控制方法及相关电路”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电网异步互联技术领域，特别涉及一种可变频率变压器故障穿越电路的控制方法及可变频率变压器故障穿越电路。
背景技术
随着电网的不断建设，不同国家之间的电网可以进行共享电能资源。其中，可以通过可变频率变压器，将不同频率的电网相互连接。采用可变频率变压器的电网异步互联，控制简单，过载能力强且不会发生换相失败，可靠性较高；在使用中不会产生谐波，电能质量更好；并且具有更强的自然阻尼和惯性支撑能力，有利于提高电网稳定性。
但是，可变频率变压器无法阻断电网故障的传播，例如，当可变频率变压器的一侧电网发生短路故障导致电压跌落时，另一侧的电网将通过可变频率变压器向故障电网传输大量短路电流，会影响无故障一侧的电网安全运行。并且，过大的短路电流和三相不对称的电流还会导致可变频率变压器的损坏。
请参考图1，图1为本申请所介绍的现有技术的可变频率变压器电网故障穿越装置结构示意图。
一般地，对于实现可变频率变压器的电网故障穿越，目前主要采用串联动态制动电阻的方式，阻止故障传播。在两侧电网均正常运行时，通过旁路开关短接全部串联制动电阻；当某一侧电网发生电压跌落故障时，根据电网电压的跌落程度断开相应的旁路开关，使串联动态制动电阻接入电网，抑制短路造成的电流异常升高，提高可变频率变压器的机端电压，避免故障从故障侧电网蔓延到正常侧电网。
虽然可以通过多个电阻之间的多种串联组合应对不同程度的电压跌落故障，但有限的电阻组合方式无法实现对可变频率变压器两端电压的完全补偿，对短路电流的限制效果有限，效率低，且大量电能损耗在串联动态制动电阻上，造成不必要的电能损耗。此外，当某一侧电网发生电压不对称跌落故障时，还 会导致可变频率变压器的转矩波动，缩短机械部件的寿命，同时产生巨大的噪音污染。
因此，如何更好的解决电网电压跌落时可变频率变压器的控制问题，是本领域技术人员所关注的重点问题。
发明内容
本申请的目的是提供一种可变频率变压器故障穿越电路的控制方法及可变频率变压器故障穿越电路，当发生电网电压跌落故障时，利用补偿电路进行电压补偿，进而可以提升电压，降低短路带来的大量短路电流，避免了过多的电能损耗，防止电压跌落故障跌落到电网的另一侧。
为解决上述技术问题，本申请实施例提供的一种可变频率变压器故障穿越电路的控制方法，所述可变频率变压器故障穿越电路，包括：第一电网、第二电网、可变频率变压器、第一补偿变压器和第一PWM变换器；所述第一电网经所述第一补偿变压器的次级线圈连接所述可变频率变压器的定子接口，所述第一补偿变压器的初级线圈串联在所述第一PWM变换器的第一输出端和第二输出端之间，所述可变频率变压器的转子接口与所述第二电网连接；所述方法，包括：
对采集的所述第一电网的电压U g1abc、所述第二电网的电压U g2abc、所述可变频率变压器的定子接口电压U sabc以及转子接口电压U rabc进行预处理，得到定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-；
将所述第一电网的电压U g1abc和所述第二电网的电压U g2abc经过数字锁相环检测处理，得到所述第一电网的电压频率f g1和所述第二电网的电压频率f g2；
将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网的电压频率f g1以及所述第二电网的电压频率f g2进行参考电压计算处理，得到所述第一PWM变换器的电压参考值U t1dq+和电压参考值U t1dq-；
对所述电压参考值U t1dq+、所述电压参考值U t1dq-进行控制信号获取处理，得到控制所述第一PWM变换器的开关信号S a、S b、S c。
可选的，所述对采集的第一电网的电压U g1abc、所述第二电网的电压U g2abc、所述可变频率变压器的定子接口电压U sabc以及转子接口电压U rabc进行预处理， 得到定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-，具体包括：
利用电压传感器采集所述第一电网的电压U g1abc、所述第二电网的电压U g2abc、定子接口电压U sabc以及转子接口电压U rabc；
将所述第一电网电压U g1abc、所述第二电网电压U g2abc、所述定子接口电压U sabc以及所述转子接口电压U rabc分别经过三相静止两相静止坐标变换处理，得到在两相静止坐标系下包含正、负序分量的第一电网电压综合矢量U g1αβ、第二电网电压综合矢量U g2αβ、定子电压综合矢量U sαβ以及转子电压综合矢量U rαβ；
将所述第一电网电压综合矢量U g1αβ和所述第二电网电压综合矢量U g2αβ分别经过正负序信号分离处理，得到在两相静止坐标系下的第一电网正序电压矢量U g1αβ+、第一电网负序电压矢量U g1αβ-、第二电网正序电压矢量U g2αβ+以及第二电网负序电压矢量U g2αβ-；
将所述第一电网正序电压矢量U g1αβ+、所述第一电网负序电压矢量U g1αβ-、所述第二电网正序电压矢量U g2αβ+以及所述第二电网负序电压矢量U g2αβ-分别经过相角计算处理，得到第一电网正序电压相位θ g1+、第一电网负序电压相位θ g1-、第二电网正序电压相位θ g2+以及第二电网负序电压相位θ g2-；
将所述定子电压综合矢量U sαβ与所述转子电压综合矢量U rαβ分别经过正负序信号分离处理，得到在两相静止坐标系下定子正序电压矢量U sαβ+、定子负序电压矢量U sαβ-、转子正序电压矢量U rαβ+以及转子负序电压矢量U rαβ-；
将得到的所述定子正序电压矢量U sαβ+、所述定子负序电压矢量U sαβ-、所述转子正序电压矢量U rαβ+以及所述转子负序电压矢量U rαβ-分别经过两相静止到两相旋转坐标变换处理，得到在同步旋转坐标系下定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-。
可选的，所述将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2参考电压计算处理，得到所述第一PWM变换器的电压参考值U t1dq+和电压参考值U t1dq-，具体包括：
将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所 述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2按照第一预设电压控制方程进行处理，得到所述第一PWM变换器的电压参考值U t1dq+和电压参考值U t1dq-；
所述第一预设电压控制方程分别如下：
Figure PCTCN2018080591-appb-000001
Figure PCTCN2018080591-appb-000002
Figure PCTCN2018080591-appb-000003
Figure PCTCN2018080591-appb-000004
其中，所述K p3和所述K i3分别是第一PWM变换器正序电压PI调节器的比例系数和积分系数，所述K p4和所述K i4分别是所述第一PWM变换器负序电压PI调节器的比例系数和积分系数。
可选的，所述对所述电压参考值U t1dq+、所述电压参考值U t1dq-进行控制信号获取处理，得到控制所述第一PWM变换器的开关信号S a、S b、S c，具体包括：
将所述电压参考值U t1dq+、所述电压参考值U t1dq-进行两相旋转到两相静止坐标变换处理，得到在两相静止坐标系下所述第一PWM变换器的电压参考信号U t1αβ+和电压参考信号U t1αβ-；
将所述电压参考信号U t1αβ+、所述电压参考信号U t1αβ-分别相加，得到在两相静止坐标系下所述第一PWM变换器的电压参考信号U t1αβ；
将所述电压参考信号U t1αβ通过空间矢量脉宽调制模块，得到控制所述第一PWM变换器的开关信号S a、S b、S c。
可选的，所述可变频率变压器故障穿越电路，还包括：第二补偿变压器和第二PWM变换器；所述第二补偿变压器的次级线圈串联在所述第二电网和所述可变频率变压器的转子接口之间，所述第二补偿变压器的初级线圈串联在所述PWM变换器的第一输入端和第二输出端之间，所述方法，还包括：
将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电 网电压频率f g1以及所述第二电网电压频率f g2进行参考电压计算处理，得到所述第二PWM变换器的电压参考值U t2dq+、电压参考值U t2dq-；
对所述电压参考值U t2dq+以及电压参考值U t2dq-进行控制信号获取处理，得到控制所述第二PWM变换器的开关信号S a、S b、S c。
可选的，所述将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2参考电压计算处理，得到所述第二PWM变换器的电压参考值U t2dq+和电压参考值U t2dq-，具体包括：
将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2按照第二预设电压控制方程进行处理，得到所述第二PWM变换器的电压参考值U t2dq+、电压参考值U t2dq-；
所述第二预设电压控制方程分别如下：
Figure PCTCN2018080591-appb-000005
Figure PCTCN2018080591-appb-000006
Figure PCTCN2018080591-appb-000007
Figure PCTCN2018080591-appb-000008
其中，所述K p5和所述K i5分别是第二PWM变换器正序电压PI调节器的比例系数和积分系数，所述K p6和所述K i6分别是所述第二PWM变换器负序电压PI调节器的比例系数和积分系数。
可选的，所述对所述电压参考值U t2dq+以及电压参考值U t2dq-进行控制信号获取处理，得到控制所述第二PWM变换器的开关信号S a、S b、S c，具体包括：
将所述电压参考值U t2dq+、所述电压参考值U t2dq-进行两相旋转到两相静止坐标变换处理，得到在两相静止坐标系下所述第二PWM变换器的电压参考信号U t2αβ+、电压参考信号U t2αβ-；
将所述电压参考信号U t2αβ+、所述电压参考信号U t2αβ-分别相加，得到在两相静止坐标系下所述第二PWM变换器的电压参考信号U t2αβ；
将所述电压参考信号U t2αβ通过空间矢量脉宽调制模块，得到控制所述第二PWM变换器的开关信号S a、S b、S c。
本申请实施例提供的一种可变频率变压器故障穿越电路，包括第一电网(1)、第二电网(2)、可变频率变压器(3)、第一三相整流器(6)、电机驱动变换器(4)、第一补偿电路(5)以及控制电路(7)；
所述第一电网(1)连接所述第一三相整流器(6)的输入端和所述第一补偿电路(5)的第一输出端；
所述第一补偿电路(5)的第二输出端与可变频率变压器(3)的定子接口(31)连接；
所述第一三相整流器(6)的输出端与所述第一补偿电路(5)的输入端、所述电机驱动变换器(4)的输入端连接；
所述电机驱动变换器(4)与所述可变频率变压器(3)的驱动电机连接；
所述可变频率变压器(3)的转子接口(32)与所述第二电网(2)连接；
所述控制电路(7)与所述第一补偿电路(5)的控制信号输入端连接。
可选的，所述第一补偿电路(5)，包括：第一补偿变压器(51)和第一PWM变换器(52)；
所述第一补偿变压器(51)的次级线圈串联在所述第一电网(1)和所述可变频率变压器(3)的定子接口(31)之间；
所述第一PWM变换器(52)的输出端与所述第一补偿变压器(51)的输入端连接；所述第一PWM变换器(52)的输入端与所述第一补偿电路(5)的输入端连接；所述第一PWM变换器(52)的控制信号输入端与所述第一补偿电路(5)的控制信号输入端连接。
可选的，所述第一补偿电路(5)的输入端与第一电容连接。
可选的，其特征在于，还包括：第二三相整流器(8)与第二补偿电路(9)；
所述第二电网(2)与所述第二三相整流器(8)的输入端和所述第二补偿电路(9)的第一输出端；
所述第二补偿电路(9)的第二输出端与可变频率变压器(3)的转子接口(32)连接；
所述第二三相整流器(8)的输出端与所述第二补偿电路(9)的输入端、所述第一三相整流器(6)的输出端连接；
所述第二补偿电路(9)的控制信号输入端与所述控制电路(7)连接。
可选的，所述第二补偿电路(9)，包括：第二补偿变压器(91)和第二PWM变换器(92)；
所述第二补偿变压器(91)的次级线圈串联在所述第二电网(2)和所述可变频率变压器(3)的转子接口(32)之间；所述第二补偿变压器(91)的初级线圈串联在所述第二PWM变换器(92)的第一输入端和第二输入端之间；
所述第二PWM变换器(92)的输入端与所述第二补偿电路(9)的输入端连接；
所述第二PWM变换器(92)的控制信号输入端与所述第二补偿电路(9)的控制信号输入端连接。
可选的，所述第二补偿电路(9)的输入端与第二电容连接。
通过当发生电网电压跌落故障时，进行电压补偿，进而可以提升电压，降低短路带来的大量短路电流，避免了过多的电能损耗，防止电压跌落故障跌落到电网的另一侧。同时，避免了电网电压不对称跌落故障时，可变频率变压器产生转矩波动，延长机械部件的寿命，同时避免产生噪音污染。
本申请还提供一种可变频率变压器故障穿越电路，具有上述有益效果，在此不做赘述。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简要介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域的普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请所介绍的现有技术的可变频率变压器电网故障穿越装置结构示意图；
图2为本申请实施例所提供的一种可变频率变压器故障穿越电路的结构示意图；
图3为本申请实施例所提供的可变频率变压器故障穿越电路中的补偿电路的结构示意图；
图4为本申请实施例所提供的另一种可变频率变压器故障穿越电路的结构示意图；
图5为本申请实施例所提供的一种可变频率变压器故障穿越电路的控制方法的流程图；
图6为本申请实施例所提供的一种可变频率变压器故障穿越电路的控制方法的控制框图；
图7为本申请实施例所提供的另一种可变频率变压器故障穿越电路的控制方法的控制框图；
图2至图4中：
1为第一电网、2为第二电网、3为可变频率变压器、31为定子接口、32为转子接口、4为电机驱动变换器、5为第一补偿电路、51为第一补偿变压器、52为第一PWM变换器、6为第一三相整流器、7为控制电路、8为第二三相整流器、9为第二补偿电路、91为第二补偿变压器、92为第二PWM变换器。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
本申请实施例的核心是提供一种可变频率变压器故障穿越电路及其控制方法，当发生电网电压跌落故障时，利用补偿电路进行电压补偿，进而可以提升电压，降低短路带来的大量短路电流，避免了过多的电能损耗，防止电压跌落故障跌落到电网的另一侧。
第一实施例：
请参考图2，图2为本申请实施例所提供的一种可变频率变压器故障穿越电路的结构示意图。
本实施例提供一种可变频率变压器故障穿越电路，可通过补偿无功功率的方式提高电路电压降低短路电流，防止电压跌落故障跌落至电网另一侧，该可变频率变压器故障穿越电路，可以包括：第一电网1、第二电网2、可变频率变压器3、第一三相整流器6、电机驱动变换器4、第一补偿电路5以及控制电路7；
第一电网1连接第一三相整流器6的输入端和第一补偿电路5的第一输出端；
第一补偿电路5的第二输出端与可变频率变压器3的定子接口31连接；
第一三相整流器6的输出端与第一补偿电路5的输入端、电机驱动变换器4的输入端连接；
电机驱动变换器4的输出端与可变频率变压器3的驱动电机连接；
可变频率变压器3的转子接口32与第二电网2连接；
控制电路7与第一补偿电路5的控制信号输入端连接。
本实施例的电路主要是通过第一三相整流器6获取直流电，供给电机驱动变换器4，以使可变频率变压器3可以正常运转。但是在电网供电中不可避免的会出现电路的故障，其中电路短路是常见的电路故障。当一侧电网发生短路时，会导致电压跌落也就是一侧的电网的电压会迅速降低，另一侧的电网则会被迫通过可变频率变压器向故障侧传输大量短路电流，会影响无故障侧电网的安全运行，同时过大的短路电流还会导致可变频率变压器的损坏。因此，需要抑制故障侧的电压跌落，防止故障穿越至另一侧电网。
通常为了防止电压跌落故障会在电网构建自动控制装置，当出现短路故障导致电压跌落出现大量短路电流时，通过自动控制装置将负载即电阻连入电网，抑制短路电流，提高可变频率变压器的极端电压，从而避免故障从故障侧蔓延至正常侧电网。但是，连入负载的方式由于电阻受物理限制，只能进行有限的补偿，对短路电流的限制效果有限，并且有大量的电能消耗在电阻上浪费了大量的能源。
本实施例提供的第一补偿电路5可以通过控制电路的控制信号和补偿电路对第一电网1进行电压补偿。当第一电网1出现电压跌落故障时就可以通过电压补偿提高第一电网1侧的电压，进一步的可以降低短路造成的大量短路电流。
可选的，该电压补偿可以通过无功补偿实现。无功补偿，全称无功功率补偿，是一种在电力供电系统中起提高电网的功率因数的作用，降低供电变压器及输送线路的损耗，提高供电效率，改善供电环境的技术。在电路中实施无功补偿，会提高电路的功率因数
Figure PCTCN2018080591-appb-000009
同时还可以提高系统电压、降低变压器和线路的消耗，以及提高变压器、线路的带负载能力。
实施无功补偿后，电路中消耗的部分无功电流不再需要从系统吸收，从而使得补偿电路的压降减小，所以提高了电压，同时可以使电流减小，会使得线路、变压器的损耗减小；部分无功电流不从系统吸收，使得线路、变压器可以更多地传输有功电能，提高了设备的带负载能力。
综上，本实施例提供一种电压补偿电路，可以通过补偿电路当发生电网电压跌落故障时，进行电压补偿，进而可以提升电压，降低短路带来的大量短路电流，避免了过多的电能损耗，防止电压跌落故障跌落到电网的另一侧。
需要说明的是，本实施中的电路为对侧电路，也就是第一电网1和第二电网2，但是只在第一电网1安装了第一补偿电路5，也就是说只能防止一侧的电压跌落故障穿越。
请参考图3，图3为本申请实施例所提供的可变频率变压器故障穿越电路中的补偿电路的结构示意图。
基于上一实施例，本实施例旨在针对上一实施例中的补偿电路做一个具体说明，其他部分与上一实施例大体相同，相同部分可以参考上一实施例，在此不再赘述。
本实施中，第一补偿电路5具体可以包括：第一补偿变压器51和第一PWM变换器52；
第一补偿变压器51的次级线圈串联在第一电网1和可变频率变压器3的定子接口31之间；第一补偿变压器51的初级线圈串联在第一PWM变换器52的第一输出端和第二输出端之间；
第一PWM变换器52的输出端与第一补偿变压器51的输入端连；第一PWM变换器52的输入端与第一补偿电路5的输入端连接；第一PWM变换器52的控制信号输入端与第一补偿电路5的控制信号输入端连接。
其中，第一PWM变换器52通过接收控制电路7的控制信号可以使其输出相应的电流，通过第一补偿变压器51补偿进电网电路中。第一PWM变换器52可以通过接收控制电路7的开关信号将直流电整流为相应的三相交流电，因此，PWM变换器也可以是PWM整流器。
其中，控制电路7主要是执行相应的控制信号的算法得到对应的控制信号，因此控制电路7可以是DSP控制板，也可以是嵌入式控制板，还可以是单片机。一般控制电路7为弱电电路，只向PWM变换器提供控制信号。
进一步的，控制电路7中的算法可以根据实际应用环境的需要对算法进行相应的修改，在此不做限定。
可选的，本实施例中，第一补偿电路5的输入端通过第一电容接地。
第二实施例：
请参考图4，图4为本申请实施例所提供的另一种可变频率变压器故障穿越电路的结构示意图。
本申请实施例所提供的第一种电压补偿电路为单侧补偿，无法解决另一侧的电压跌落问题，因此基于第一种电压补偿电路实施例，本实施针对两侧都出现的电压跌落问题，做一个补充说明，其他部分与上一实施例大体相同，相同部分可以参考上一实施例，在此不做赘述。
基于第一实施例，本实施例提供的可变频率变压器故障穿越电路，还可以包括：第二三相整流器8与第二补偿电路9；
第二电网2连接第二三相整流器8的输入端和第二补偿电路9的第一输出端；
第二补偿电路9的第二输出端与可变频率变压器3的转子接口32连接；
第二三相整流器8的输出端与第二补偿电路9的输入端、第一三相整流器6的输出端连接；
第二补偿电路9的控制信号输入端与控制电路7连接。
可选的，第二补偿电路9可以包括：第二补偿变压器91和第二PWM变换器92；
第二补偿变压器91的次级线圈串联在第二电网2和可变频率变压器3的转子接口32之间；第二补偿变压器91的初级线圈串联在第二PWM变换器92的第一输入端和第二输出端之间；
第二PWM变换器92的输入端与第二补偿电路9的输入端连接；第二PWM变换器92的控制信号输入端与第二补偿电路9的控制信号输入端连接。
本实施例采用第二三相整流器8将电路结构变为对称结构，再在第二电网2和直流电路中连接第二补偿电路9，整体电路形成对称结构，可以解决另一侧的电压跌落故障问题。
具体内容与第一实施例大体相同，在此不作赘述。
需要注意的是，由于第二补偿电路9同样需要控制电路7进行控制，因此控制电路7中的算法需要做适应性改变，但是控制信号的算法与上述大体相同，具体在此不做赘述。
可选的，第二补偿电路9的输入端通过第二电容接地。
本申请实施例提供了一种电压补偿电路，可以通过补偿电路当发生电网电压跌落故障时，进行电压补偿，进而可以提升电压，降低短路带来的大量短路电流，避免了过多的电能损耗，防止电压跌落故障跌落到电网的另一侧。
基于上述实施例提供的可变频率变压器故障穿越电路，下面对本申请实施例提供的一种可变频率变压器故障穿越电路的控制方法进行介绍。下文描述的一种可变频率变压器故障穿越电路的控制方法与上文描述的一种可变频率变压器故障穿越电路可相互对应参照。
请参考图5，图5为本申请实施例所提供的一种可变频率变压器故障穿越电路的控制方法的流程图。
本实施例提供一种可变频率变压器故障穿越电路的控制方法，可以防止故障电压穿越可变频率变压器，应用于上述任意实施例提供的可变频率变压器故障穿越电路，下面结合图2进行说明。
本实施例提供一种可变频率变压器故障穿越电路的控制方法，可以包括：
S101，对采集的第一电网的电压U g1abc、第二电网的电压U g2abc、可变频率变压器的定子接口电压U sabc以及转子接口电压U rabc进行预处理，得到定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-；
S102，将第一电网的电压U g1abc和第二电网的电压U g2abc通过数字锁相环检测处理得到第一电网的电压频率f g1和第二电网电压的频率f g2；
S103，将定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+、转子负序电压直流分量U rdq-、第一电网的电压频率f g1以及第二电网的电压频率f g2进行参考电压计算处理，得到第一PWM变换器的电压参考值U t1dq+、电压参考值U t1dq-；
S104，对电压参考值U t1dq+、电压参考值U t1dq-进行控制信号获取处理，得到控制第一PWM变换器的开关信号S a、S b、S c。
在一些可能的设计中，本申请实施例还可以提供另一种可变频率变压器故障穿越电路的控制方法，应用于图3或图4所示的可变频率变压器故障穿越电路。
则S103，具体还可以包括：将定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+、转子负序电压直流分量U rdq-、第一电网的电压频率f g1以及第二电网的电压频率f g2进行参考电压计算处理，得到第一PWM变换器的电压参考值U t1dq+、电压参考值U t1dq-与第二PWM变换器的电压参考值U t2dq+、电压参考值U t2dq-；
S104，具体还可以包括：对电压参考值U t1dq+、电压参考值U t1dq-、电压参考值U t2dq+以及电压参考值U t2dq-进行控制信号获取处理，得到控制第一PWM变换器的开关信号S a、S b、S c以及控制第二PWM变换器的开关信号S a2、S b2、S c2。
在可变频率变压器运行过程中，有可能出现可变频率变压器某一侧的电网发生电压不对称的故障，造成流过可变频率变压器的电流不对称，进一步导致2倍的电网频率的转矩波动，会缩短机械设备的寿命。
因此，在电网电压不对称情况下，串联补偿PWM变换器通过采取电压闭环控制，可以实现可变频率变压器两端电压的完全补偿，消除电网电压不对称故障导致的转矩波动。
上述介绍的控制方法，即为对串联补偿PWM变换器进行的电压闭环控制方法。其中，预处理是指得到该可变频率变压器定子与转子正负序直流电压分量的处理，并且还通过数字锁相环得到第一电网的电压频率和第二电网的电压频率。电压计算处理主要是根据电压控制方程进行计算得到电压参考值，具体的电压控制方法可以根据具体的应用环境进行设定，在此不做赘述。
将得到的电压参考值进行控制信号处理，就可以得到控制变换器进行开关控制的控制信号，进而控制串联补偿PWM变换器进行相关的变换得到补偿电压以控制电路进行补偿。
请参考图6，图6为本申请实施例所提供的一种可变频率变压器故障穿越电路的控制方法的控制框图。
基于上一实施例中的步骤，并结合图4所示的控制框图，本实施例可以提供一种可变频率变压器故障穿越电路的控制方法，可以包括：
(1)利用电压传感器采集第一电网的电压U g1abc、第二电网的电压U g2abc、可变频率变压器的定子接口电压U sabc以及转子接口电压U rabc；
(2)将第一电网的电压U g1abc和第二电网的电压U g2abc经过数字锁相环检测处理，得到第一电网的电压频率f g1和第二电网的电压频率f g2；
(3)将第一电网的电压U g1abc、第二电网的电压U g2abc、定子接口电压U sabc以及转子接口电压U rabc分别经过三相静止两相静止坐标变换处理，得到在两相静止坐标系下包含正、负序分量的第一电网电压综合矢量U g1αβ、第二电网电压综合矢量U g2αβ、定子电压综合矢量U sαβ以及转子电压综合矢量U rαβ；
(4)将第一电网电压综合矢量U g1αβ和第二电网电压综合矢量U g2αβ分别经过正负序信号分离处理，得到在两相静止坐标系下的第一电网正序电压矢量U g1αβ+、第一电网负序电压矢量U g1αβ-、第二电网正序电压矢量U g2αβ+以及第二电网负序电压矢量U g2αβ-，将第一电网正序电压矢量U g1αβ+、第一电网负序电压矢量U g1αβ-、第二电网正序电压矢量U g2αβ+以及第二电网负序电压矢量U g2αβ-分别经过相角计算处理，得到第一电网正序电压相位θ g1+、第一电网负序电压相位θ g1-、第二电网正序电压相位θ g2+以及第二电网负序电压相位θ g2-；
(5)将定子电压综合矢量U sαβ与转子电压综合矢量U rαβ分别经过正负序信号分离处理，得到在两相静止坐标系下定子正序电压矢量U sαβ+、定子负序电压矢量U sαβ-、转子正序电压矢量U rαβ+以及转子负序电压矢量U rαβ-；
(6)将得到的定子正序电压矢量U sαβ+、定子负序电压矢量U sαβ-、转子正序电压矢量U rαβ+以及转子负序电压矢量U rαβ-分别经过两相静止到两相旋转坐标变换处理，得到在同步旋转坐标系下定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-；
(7)将定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+、转子负序电压直流分量U rdq-、第一电网电压频率f g1以及第二电网电压频率f g2按照第一预设电压控制方程和第二预设电压控制方程进行处理，得到第一PWM变换器的电压参考值U t1dq+、电压参考值U t1dq-以及第二PWM变换器的电压参考值U t2dq+、电压参考值U t2dq-；
其中，第一预设电压控制方程和第二预设电压控制方程分别如下：
Figure PCTCN2018080591-appb-000010
Figure PCTCN2018080591-appb-000011
Figure PCTCN2018080591-appb-000012
Figure PCTCN2018080591-appb-000013
Figure PCTCN2018080591-appb-000014
Figure PCTCN2018080591-appb-000015
Figure PCTCN2018080591-appb-000016
Figure PCTCN2018080591-appb-000017
其中，K p3和K i3分别是第一PWM变换器正序电压PI调节器的比例系数和积分系数，K p4和K i4分别是第一PWM变换器负序电压PI调节器的比例系数和积分系数，K p5和K i5分别是第二PWM变换器正序电压PI调节器的比例系数和积分系数，K p6和K i6分别是第二PWM变换器负序电压PI调节器的比例系数和积分系数；
(8)将电压参考值U t1dq+、电压参考值U t1dq-、电压参考值U t2dq+、电压参考值U t2dq-进行两相旋转到两相静止坐标变换处理，得到在两相静止坐标系下第一PWM变换器的电压参考信号U t1αβ+、电压参考信号U t1αβ-和第二PWM变换器的电压参考信号U t2αβ+、电压参考信号U t2αβ-；
(9)将电压参考信号U t1αβ+、电压参考信号U t1αβ-、电压参考信号U t2αβ+、电压参考信号U t2αβ-分别相加，得到在两相静止坐标系下第一PWM变换器的电压参考信号U t1αβ和第二PWM变换器的电压参考信号U t2αβ；
(10)将电压参考信号U t1αβ和电压参考信号U t2αβ通过空间矢量脉宽调制模块，得到控制第一PWM变换器的开关信号S a、S b、S c以及控制第二PWM变换器的开关信号S a、S b、S c。
通过上述步骤产生的控制信号可以使补偿电路，在电网电压不对称故障时，可以实现对可变频率变压器两端电压的完全补偿，消除电网电压不对称故障导致的可变频率变压器转矩波动。
基于上述实施例中的电路结构，本申请实施例还可以提供另一种可变频率变压器故障穿越电路的控制方法。
请参考图7，图7为本申请实施例所提供的另一种可变频率变压器故障穿越电路的控制方法的控制框图。
本实施例提供另一种补偿电路的控制信号产生方法，应用于上述第二实施例，可以产生相应的控制信号，该方法可以包括：
1)利用相应位置的电压传感器采集电网1电压U g1abc、电网2电压U g2abc、定子电压U sabc以及转子电压U rabc；
2)采集得到的三相电网1电压U g1abc和电网2电压U g2abc经过数字锁相环检测，得到电网1电压频率f g1和电网2电压频率f g2；
3)将采集到的三相电网1、电网2电压U g1abc、U g2abc和三相定、转子电压U sabc、U rabc分别经过三相静止/两相静止坐标变换模块，得到在两相静止坐标系下电网1、电网2电压矢量U g1αβ、U g2αβ和定、转子电压矢量U sαβ、U rαβ；
4)将得到的电网1、电网2电压矢量U g1αβ、U g2αβ分别经过相角计算模块，得到电网1、电网2电压相位θ g1、θ g2；
5)将得到的定、转子电压矢量U sαβ、U rαβ分别经过两相静止/同步旋转坐标变换模块，得到在同步旋转坐标系下定、转子电压直流分量U sdq、U rdq；
6)在同步旋转坐标系下串联补偿PWM变换器1和串联补偿PWM变换器2的电压控制方程分别如下：
Figure PCTCN2018080591-appb-000018
Figure PCTCN2018080591-appb-000019
Figure PCTCN2018080591-appb-000020
Figure PCTCN2018080591-appb-000021
K p1和K i1分别是串联补偿PWM变换器1电压PI调节器的比例系数和积分系数，K p2和K i2分别是串联补偿PWM变换器2电压PI调节器的比例系数和积分系数；
7)将得到的串联补偿PWM变换器1和串联补偿PWM变换器2的电压参考值U t1dq、U t2dq分别通过同步旋转/两相静止坐标变换模块，得到在两相静止坐标系下串联补偿PWM变换器1和串联补偿PWM变换器2的电压参考信号U t1αβ、U t2αβ；
8)将得到的串联补偿PWM变换器1和串联补偿PWM变换器2的电压参考信号U t1αβ、U t2αβ分别通过空间矢量脉宽调制模块，调制后分别获得控制串联补 偿PWM变换器1和串联补偿PWM变换器2功率器件的开关信号S a、S b、S c。
其中，电网1与电网2即为上述实施例中的第一电网1和第二电网2，串联补偿PWM变换器1和串联补偿PWM变换器2即为上述实施例中的第一PWM变换器52和第二PWM变换器92。
其中，本实施例由于应用在对称的电路结构，具有两个补偿电路，两个补偿电路的控制信号在一定程度上有对称的关系，因此可以根据同样的预设控制方程计算出一对控制信号，即第一补偿电路和第二补偿电路的控制信号。
当出现电压跌落的故障时，通过本实施例获取的控制信号就可以控制补偿电路中的PWM变换器和补偿变压器进行电压补偿，提高相应的系统电压，减少相应的电流，避免故障穿越至另一侧电网。
说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。对于实施例公开的装置而言，由于其与实施例公开的方法相对应，所以描述的比较简单，相关之处参见方法部分说明即可。
专业人员还可以进一步意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、计算机软件或者二者的结合来实现，为了清楚地说明硬件和软件的可互换性，在上述说明中已经按照功能一般性地描述了各示例的组成及步骤。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
结合本文中所公开的实施例描述的方法或算法的步骤可以直接用硬件、处理器执行的软件模块，或者二者的结合来实施。软件模块可以置于随机存储器(RAM)、内存、只读存储器(ROM)、电可编程ROM、电可擦除可编程ROM、寄存器、硬盘、可移动磁盘、CD-ROM、或技术领域内所公知的任意其它形式的存储介质中。
以上对本申请所提供的一种可变频率变压器故障穿越电路的控制方法及可变频率变压器故障穿越电路进行了详细介绍。本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的方法及其核心思想。应当指出，对于本技术领域的普通技术人员来说，在不 脱离本申请原理的前提下，还可以对本申请进行若干改进和修饰，这些改进和修饰也落入本申请权利要求的保护范围内。

Claims (13)

  1. 一种可变频率变压器故障穿越电路的控制方法，其特征在于，所述可变频率变压器故障穿越电路，包括：第一电网、第二电网、可变频率变压器、第一补偿变压器和第一PWM变换器；所述第一电网经所述第一补偿变压器的次级线圈连接所述可变频率变压器的定子接口，所述第一补偿变压器的初级线圈串联在所述第一PWM变换器的第一输出端和第二输出端之间，所述可变频率变压器的转子接口与所述第二电网连接；所述方法，包括：
    对采集的所述第一电网的电压U g1abc、所述第二电网的电压U g2abc、所述可变频率变压器的定子接口电压U sabc以及转子接口电压U rabc进行预处理，得到定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-；
    将所述第一电网的电压U g1abc和所述第二电网的电压U g2abc经过数字锁相环检测处理，得到所述第一电网的电压频率f g1和所述第二电网的电压频率f g2；
    将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网的电压频率f g1以及所述第二电网的电压频率f g2进行参考电压计算处理，得到所述第一PWM变换器的电压参考值U t1dq+和电压参考值U t1dq-；
    对所述电压参考值U t1dq+、所述电压参考值U t1dq-进行控制信号获取处理，得到控制所述第一PWM变换器的开关信号S a、S b、S c。
  2. 根据权利要求1所述的控制方法，其特征在于，所述对采集的第一电网的电压U g1abc、所述第二电网的电压U g2abc、所述可变频率变压器的定子接口电压U sabc以及转子接口电压U rabc进行预处理，得到定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-，具体包括：
    利用电压传感器采集所述第一电网的电压U g1abc、所述第二电网的电压U g2abc、定子接口电压U sabc以及转子接口电压U rabc；
    将所述第一电网电压U g1abc、所述第二电网电压U g2abc、所述定子接口电压U sabc以及所述转子接口电压U rabc分别经过三相静止两相静止坐标变换处理，得到在两相静止坐标系下包含正、负序分量的第一电网电压综合矢量U g1αβ、第二 电网电压综合矢量U g2αβ、定子电压综合矢量U sαβ以及转子电压综合矢量U rαβ；
    将所述第一电网电压综合矢量U g1αβ和所述第二电网电压综合矢量U g2αβ分别经过正负序信号分离处理，得到在两相静止坐标系下的第一电网正序电压矢量U g1αβ+、第一电网负序电压矢量U g1αβ-、第二电网正序电压矢量U g2αβ+以及第二电网负序电压矢量U g2αβ-；
    将所述第一电网正序电压矢量U g1αβ+、所述第一电网负序电压矢量U g1αβ-、所述第二电网正序电压矢量U g2αβ+以及所述第二电网负序电压矢量U g2αβ-分别经过相角计算处理，得到第一电网正序电压相位θ g1+、第一电网负序电压相位θ g1-、第二电网正序电压相位θ g2+以及第二电网负序电压相位θ g2-；
    将所述定子电压综合矢量U sαβ与所述转子电压综合矢量U rαβ分别经过正负序信号分离处理，得到在两相静止坐标系下定子正序电压矢量U sαβ+、定子负序电压矢量U sαβ-、转子正序电压矢量U rαβ+以及转子负序电压矢量U rαβ-；
    将得到的所述定子正序电压矢量U sαβ+、所述定子负序电压矢量U sαβ-、所述转子正序电压矢量U rαβ+以及所述转子负序电压矢量U rαβ-分别经过两相静止到两相旋转坐标变换处理，得到在同步旋转坐标系下定子正序电压直流分量U sdq+、定子负序电压直流分量U sdq-、转子正序电压直流分量U rdq+以及转子负序电压直流分量U rdq-。
  3. 根据权利要求1所述的控制方法，其特征在于，所述将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2参考电压计算处理，得到所述第一PWM变换器的电压参考值U t1dq+和电压参考值U t1dq-，具体包括：
    将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2按照第一预设电压控制方程进行处理，得到所述第一PWM变换器的电压参考值U t1dq+和电压参考值U t1dq-；
    所述第一预设电压控制方程分别如下：
    Figure PCTCN2018080591-appb-100001
    Figure PCTCN2018080591-appb-100002
    Figure PCTCN2018080591-appb-100003
    Figure PCTCN2018080591-appb-100004
    其中，所述K p3和所述K i3分别是第一PWM变换器正序电压PI调节器的比例系数和积分系数，所述K p4和所述K i4分别是所述第一PWM变换器负序电压PI调节器的比例系数和积分系数。
  4. 根据权利要求3所述的控制方法，其特征在于，所述对所述电压参考值U t1dq+、所述电压参考值U t1dq-进行控制信号获取处理，得到控制所述第一PWM变换器的开关信号S a、S b、S c，具体包括：
    将所述电压参考值U t1dq+、所述电压参考值U t1dq-进行两相旋转到两相静止坐标变换处理，得到在两相静止坐标系下所述第一PWM变换器的电压参考信号U t1αβ+和电压参考信号U t1αβ-；
    将所述电压参考信号U t1αβ+、所述电压参考信号U t1αβ-分别相加，得到在两相静止坐标系下所述第一PWM变换器的电压参考信号U t1αβ；
    将所述电压参考信号U t1αβ通过空间矢量脉宽调制模块，得到控制所述第一PWM变换器的开关信号S a、S b、S c。
  5. 根据权利要求1-4任意一项所述的控制方法，其特征在于，所述可变频率变压器故障穿越电路，还包括：第二补偿变压器和第二PWM变换器；所述第二补偿变压器的次级线圈串联在所述第二电网和所述可变频率变压器的转子接口之间，所述第二补偿变压器的初级线圈串联在所述PWM变换器的第一输入端和第二输出端之间，所述方法，还包括：
    将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2进行参考电压计算处理，得到所述第二PWM变换器的电压参考值U t2dq+、电压参考值U t2dq-；
    对所述电压参考值U t2dq+以及电压参考值U t2dq-进行控制信号获取处理，得到控制所述第二PWM变换器的开关信号S a、S b、S c。
  6. 根据权利要求5所述的控制方法，其特征在于，所述将所述定子正序 电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2参考电压计算处理，得到所述第二PWM变换器的电压参考值U t2dq+和电压参考值U t2dq-，具体包括：
    将所述定子正序电压直流分量U sdq+、所述定子负序电压直流分量U sdq-、所述转子正序电压直流分量U rdq+、所述转子负序电压直流分量U rdq-、所述第一电网电压频率f g1以及所述第二电网电压频率f g2按照第二预设电压控制方程进行处理，得到所述第二PWM变换器的电压参考值U t2dq+、电压参考值U t2dq-；
    所述第二预设电压控制方程分别如下：
    Figure PCTCN2018080591-appb-100005
    Figure PCTCN2018080591-appb-100006
    Figure PCTCN2018080591-appb-100007
    Figure PCTCN2018080591-appb-100008
    其中，所述K p5和所述K i5分别是第二PWM变换器正序电压PI调节器的比例系数和积分系数，所述K p6和所述K i6分别是所述第二PWM变换器负序电压PI调节器的比例系数和积分系数。
  7. 根据权利要求6所述的控制方法，其特征在于，所述对所述电压参考值U t2dq+以及电压参考值U t2dq-进行控制信号获取处理，得到控制所述第二PWM变换器的开关信号S a、S b、S c，具体包括：
    将所述电压参考值U t2dq+、所述电压参考值U t2dq-进行两相旋转到两相静止坐标变换处理，得到在两相静止坐标系下所述第二PWM变换器的电压参考信号U t2αβ+、电压参考信号U t2αβ-；
    将所述电压参考信号U t2αβ+、所述电压参考信号U t2αβ-分别相加，得到在两相静止坐标系下所述第二PWM变换器的电压参考信号U t2αβ；
    将所述电压参考信号U t2αβ通过空间矢量脉宽调制模块，得到控制所述第二PWM变换器的开关信号S a、S b、S c。
  8. 一种可变频率变压器故障穿越电路，其特征在于，包括第一电网(1)、 第二电网(2)、可变频率变压器(3)、第一三相整流器(6)、电机驱动变换器(4)、第一补偿电路(5)以及控制电路(7)；
    所述第一电网(1)连接所述第一三相整流器(6)的输入端和所述第一补偿电路(5)的第一输出端；
    所述第一补偿电路(5)的第二输出端与可变频率变压器(3)的定子接口(31)连接；
    所述第一三相整流器(6)的输出端与所述第一补偿电路(5)的输入端、所述电机驱动变换器(4)的输入端连接；
    所述电机驱动变换器(4)与所述可变频率变压器(3)的驱动电机连接；
    所述可变频率变压器(3)的转子接口(32)与所述第二电网(2)连接；
    所述控制电路(7)与所述第一补偿电路(5)的控制信号输入端连接。
  9. 根据权利要求8所述的可变频率变压器故障穿越电路，其特征在于，所述第一补偿电路(5)，包括：第一补偿变压器(51)和第一PWM变换器(52)；
    所述第一补偿变压器(51)的次级线圈串联在所述第一电网(1)和所述可变频率变压器(3)的定子接口(31)之间；
    所述第一PWM变换器(52)的输出端与所述第一补偿变压器(51)的输入端连接；所述第一PWM变换器(52)的输入端与所述第一补偿电路(5)的输入端连接；所述第一PWM变换器(52)的控制信号输入端与所述第一补偿电路(5)的控制信号输入端连接。
  10. 根据权利要求9所述的可变频率变压器故障穿越电路，其特征在于，所述第一补偿电路(5)的输入端与第一电容连接。
  11. 根据权利要求8-10任意一项所述的可变频率变压器故障穿越电路，其特征在于，还包括：第二三相整流器(8)与第二补偿电路(9)；
    所述第二电网(2)与所述第二三相整流器(8)的输入端和所述第二补偿电路(9)的第一输出端；
    所述第二补偿电路(9)的第二输出端与可变频率变压器(3)的转子接口(32)连接；
    所述第二三相整流器(8)的输出端与所述第二补偿电路(9)的输入端、所述第一三相整流器(6)的输出端连接；
    所述第二补偿电路(9)的控制信号输入端与所述控制电路(7)连接。
  12. 根据权利要求11所述的可变频率变压器故障穿越电路，其特征在于， 所述第二补偿电路(9)，包括：第二补偿变压器(91)和第二PWM变换器(92)；
    所述第二补偿变压器(91)的次级线圈串联在所述第二电网(2)和所述可变频率变压器(3)的转子接口(32)之间；所述第二补偿变压器(91)的初级线圈串联在所述第二PWM变换器(92)的第一输入端和第二输入端之间；
    所述第二PWM变换器(92)的输入端与所述第二补偿电路(9)的输入端连接；
    所述第二PWM变换器(92)的控制信号输入端与所述第二补偿电路(9)的控制信号输入端连接。
  13. 根据权利要求12所述的可变频率变压器故障穿越电路，其特征在于，所述第二补偿电路(9)的输入端与第二电容连接。
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