JP2014042390A - Self-excited power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-excited power conversion device that performs serial communication to a plurality of unit converters and has high operational continuity to an anomaly in a line for serial communication.SOLUTION: A self-excited power conversion device 1 includes: a plurality of arms 4up-4wm comprising a plurality of cells CL11-CL64 connected in series; transmission lines L1, L2 connecting the plurality of cells CL11-CL64 in loops for serial communication; and a control device 3 for transmitting two data DT to the transmission lines L1, L2 such that they are received by the plurality of cells CL11-CL64 in opposite orders to each other.

Description

  The present invention relates to a self-excited power conversion device.

  In general, an MMC (modular multilevel converter) is known as a self-excited power converter. The MMC is a power conversion device configured with a plurality of cells (unit converters). The MMC is controlled by a gate pulse (gate signal) input to each cell. An optical fiber cable is used for transmission of the gate pulse. In order to shorten the optical fiber cable, it is disclosed that each cell is daisy chain connected with an optical fiber cable and an optical serial signal is transmitted to each cell (for example, see Patent Document 1).

JP 2011-24393 A

  However, when the gate signal is serially communicated to a plurality of cells, if an abnormality occurs in the cell or the like in the middle of the line for serial communication, the gate signal is not transmitted to the previous cell from the location where the abnormality has occurred. Therefore, in serial communication, if an abnormality occurs in a line even at one location, there is a possibility that a cell that cannot be driven is generated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a self-excited power conversion device that serially communicates with a plurality of unit converters and has high continuity of operation against a line abnormality for serial communication.

  A self-excited power converter according to an aspect of the present invention includes a plurality of arms in which a plurality of unit converters are connected in series, and a transmission path that connects the plurality of unit converters in a loop for serial communication. And a data transmission means for transmitting two data to the transmission line so that the receiving order of the plurality of unit converters is opposite to each other.

  According to the present invention, it is possible to provide a self-excited power conversion device that performs serial communication with a plurality of unit converters and has high continuity of operation against an abnormality in a line for serial communication.

The block diagram which shows the structure of the self-excitation power converter device which concerns on embodiment of this invention. The circuit diagram shown about the circuit of the cell concerning this embodiment. FIG. 5 is a structural diagram simply showing the structure of data transmitted to each cell by serial communication according to the present embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a configuration diagram illustrating a configuration of a self-excited power conversion device 1 according to an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part in drawing, the detailed description is abbreviate | omitted, and a different part is mainly described.

  The self-excited power converter 1 includes a DC power source 2, a control device 3, six arms 4up, 4um, 4vp, 4vm, 4wp, 4wm, three-phase reactors 5u, 5v, 5w, and a three-phase interconnected reactor. 6u, 6v, 6w are provided. The self-excited power conversion device 1 supplies three-phase AC power to AC systems 7u, 7v, and 7w having an AC power source and an AC load.

  The DC power supply 2 supplies the generated DC power to a power conversion circuit composed of six arms 4up to 4wm. The DC power source 2 is not limited to a device that generates power by itself, but may be a converter or a secondary battery that converts AC power into DC power.

  The control device 3 performs serial communication with the cells (unit converters) CL11 to CL64 configuring the arms 4up to 4wm via the transmission lines L1 and L2. The control device 3 controls the power conversion circuit by transmitting a gate signal to each of the cells CL11 to CL64 by serial communication.

  The six arms 4up to 4wm constitute a power conversion circuit that converts DC power into three-phase AC power. The arm 4up is composed of four cells CL11, CL12, CL13, and CL14 connected in series to constitute the positive side of the U phase of the power conversion circuit. The arm 4um is composed of four series-connected cells CL21, CL22, CL23, and CL24 that constitute the negative phase side of the U phase of the power conversion circuit. The arm 4vp is composed of four series-connected cells CL31, CL32, CL33, and CL34 and constitutes the V-phase positive side of the power conversion circuit. The arm 4vm is composed of four cells CL41, CL42, CL43, and CL44 connected in series to constitute the negative side of the V phase of the power conversion circuit. The arm 4wp is composed of four cells CL51, CL52, CL53, and CL54 connected in series to constitute the positive side of the W phase of the power conversion circuit. The arm 4wm is composed of four series-connected cells CL61, CL62, CL63, and CL64, which constitute the W-phase negative electrode side of the power conversion circuit.

  The cells CL11 to CL64 are connected by two transmission lines L1 and L2. The transmission lines L1 and L2 are configured by optical fiber cables and repeaters.

  The transmission line L1 daisy-chains all the cells CL11 to CL14, CL31 to CL34, and CL51 to CL54 constituting the three-phase positive-side arms 4up, 4vp, and 4wp in a loop shape. The two cells CL11 and CL54 located at both ends are connected to the control device 3 via transmission lines L1a and L1b. The transmission lines L1a and L1b are part of the transmission line L1.

  The transmission line L2 daisy-chains all the cells CL21 to CL24, CL41 to CL44, and CL61 to CL64 constituting the three-phase negative-side arms 4um, 4vm, 4wm in a loop shape. The two cells CL21 and CL64 positioned at both ends are connected to the control device 3 through transmission lines L2a and L2b. The transmission lines L2a and L2b are part of the transmission line L2.

  FIG. 2 is a circuit diagram showing a circuit of the cell CL according to the present embodiment. All the cells CL11 to CL64 have the same configuration as the cell CL shown in FIG.

  Cell CL is a double star chopper. The cell CL is a circuit composed of two switching elements SW1 and SW2, two antiparallel diodes D1 and D2, and a capacitor CD. The cell CL is a gate signal transmitted from the control device 3 and is driven when the two switching elements SW1 and SW2 are switched.

  The two switching elements SW1 and SW2 are connected in series. Antiparallel diodes D1 and D2 are connected to the two switching elements SW1 and SW2, respectively. The capacitor CD is connected in parallel with the two switching elements SW1 and SW2 connected in series. A connection point between the two switching elements SW1 and SW2 serves as a positive terminal of the cell CL. The positive terminal of the cell CL is connected to the negative terminal of the cell CL adjacent to the positive electrode side or the positive electrode side of the DC power source 2. A terminal (emitter) on the negative electrode side of the switching element SW2 located on the negative electrode side becomes a negative electrode terminal of the cell CL. The negative terminal of the cell CL is connected to the positive terminal of the cell CL adjacent to the negative electrode side or the negative electrode side of the DC power source 2.

  The U-phase reactor 5u is provided between the U-phase positive-side arm 4up and the U-phase negative-side arm 4um. An intermediate point of reactor 5u is a U-phase output point of AC power. The intermediate point of reactor 5u is connected to the U phase of AC system 7u via interconnection reactor 6u. Reactor 5u is provided to suppress a direct current component of the circulating current flowing through U-phase positive arm 4up and U-phase negative arm 4um.

  The V-phase reactor 5v is provided between the V-phase positive arm 4vp and the V-phase negative arm 4vm. An intermediate point of reactor 5v is a V-phase output point of AC power. The midpoint of reactor 5v is connected to the V phase of AC system 7v via interconnection reactor 6v. Reactor 5v is provided to suppress a direct current component of the circulating current flowing through arm 4vp on the positive side of V phase and arm 4vm on the negative side of V phase.

  The W-phase reactor 5w is provided between the W-phase positive arm 4wp and the W-phase negative arm 4wm. An intermediate point of reactor 5w is a W-phase output point of AC power. The midpoint of reactor 5w is connected to the W phase of AC system 7w via interconnection reactor 6w. Reactor 5w is provided to suppress the DC component of the circulating current flowing through W-phase positive arm 4wp and W-phase negative arm 4wm.

  The interconnecting reactors 6u, 6v, 6w are reactors provided for interconnecting the AC systems 7u, 7v, 7w. The U-phase interconnecting reactor 6u is provided between the U-phase AC system 7u and the midpoint of the U-phase reactor 5u. The V-phase interconnecting reactor 6v is provided between the V-phase AC system 7v and the midpoint of the V-phase reactor 5v. The W-phase interconnecting reactor 6w is provided between the W-phase AC system 7w and the midpoint of the W-phase reactor 5w. A three-phase interconnection transformer may be provided instead of the three-phase interconnection reactors 6u, 6v, 6w.

  Next, a configuration in which the control device 3 transmits a gate signal to each of the cells CL11 to CL64 will be described.

  FIG. 3 is a structural diagram simply showing the structure of data DT transmitted to each of the cells CL11 to CL64 by serial communication according to the present embodiment. One data DT stores twelve data DT1 to DT12 corresponding to twelve cells CL11 to CL64 performing serial communication on one transmission line L1, L2.

  The control device 3 transmits two serial communication data DT to each of the transmission lines L1 and L2. The two data DT transmitted to one transmission line L1, L2 are transmitted simultaneously so as to be reverse to each other. Accordingly, the two data DT are transmitted so that the order of the received cells CL11 to CL64 is opposite to each other.

  In the transmission line L1, the control device 3 transmits one data DT to the transmission line L1a directly connected to the cell CL11, and transmits the other data to the transmission line L1b directly connected to the cell CL54. To do. In the transmission line L2, the control device 3 transmits one data DT to the transmission line L2a directly connected to the cell CL21, and sends the other data DT to the transmission line L2b directly connected to the cell CL64. Send.

  The cells CL11 to CL64 separately receive two data DT from one transmission line L1, L2. The cells CL11 to CL64 take out the data DT1 to DT12 corresponding to themselves included in the two data DT received from the transmission lines L1 and L2, respectively. Accordingly, the cells CL11 to CL64 receive the two data DT1 to DT12 corresponding to the cells CL11 to CL64. Data DT1 to DT12 taken out by the cells CL11 to CL64 include a gate signal. The cells CL11 to CL64 are driven by the extracted gate signal. When the cells CL11 to CL64 receive only one data DT within a predetermined time, the cells CL11 to CL64 operate based on the received data DT. The predetermined time for waiting for reception of the two data DT is determined based on the time difference due to the difference in the transmission path through which the two data are transmitted.

  Next, an operation after reception of the two data DT1 to DT12 of the cells CL11 to CL64 will be described.

  The cells CL11 to CL64 compare the two received data DT1 to DT12 and determine whether the contents of the two data DT1 to DT12 are the same. When it is determined that the contents of the two data DT1 to DT12 match, the cells CL11 to CL64 are driven by the extracted gate signal. When it is determined that the contents included in the two received data DT1 to DT12 are not the same, the cells CL11 to CL64 individually determine whether there is an error in the two data DT1 to DT12 by a parity check or the like. The cells CL11 to CL64 are driven by the gate signal included in the data DT1 to DT12 determined to be normal when it is determined that only one of the two data DT1 to DT12 is normal as a result of the determination. When the cells CL11 to CL64 determine that the two data DT1 to DT12 are both abnormal, the cells CL11 to CL64 output a signal notifying the controller 3 of the abnormality. When the cells CL11 to CL64 determine that the two data DT1 to DT12 are both normal, the cells CL11 to CL64 may adopt the data DT1 to DT12 received from the transmission lines L1 and L2 having a predetermined high priority, You may output the signal which notifies the control apparatus 3 of abnormality.

  Next, the operation continuity with respect to the line abnormality of the self-excited power conversion device 1 will be described. Here, the line includes hardware (for example, transmission lines L1 and L2 or cells CL11 to CL64) necessary for serial communication and all software.

  The cell CL31 of the arm 4vp on the positive side of the V phase will be described as an example.

  The cell CL31 receives one data DT of the two data DT sequentially via the cells CL11, CL12, CL13, and CL14. The cell CL31 transmits the data DT received from the cell CL14 to the cell CL32. The cell CL31 receives another data DT sequentially through the cells CL54, CL53, CL52, CL51, CL34, CL33, CL32. The cell CL31 transmits the data DT received from the cell CL32 to the cell CL14.

  Now, it is assumed that the cell CL13 has failed and the cell CL13 cannot perform serial communication. In this case, the cell CL31 cannot receive the data DT from the cell CL14 because the transmission of the data DT by serial communication stops in the cell CL13. However, the cell CL31 can receive the data DT transmitted in the reverse direction from the cell CL32. Therefore, the cell CL13 can continue normal operation based on the data DT received from the cell CL32.

  According to the present embodiment, the transmission paths L1 and L2 for serial communication are looped, and the data DT is transmitted to the cells CL11 to CL64 from both directions of the loop transmission paths L1 and L2, thereby transmitting the transmission path. Even if a line abnormality occurs in one place during the process, data DT can be transmitted to all the cells CL11 to CL64.

  In the present embodiment, each of the arms 4up to 4wm is not limited to the four cells CL11 to CL64, and may include any number of cells. For example, each arm 4up to 4wm may include cells that are not used during one cycle of the output voltage even during normal operation in order to ensure the redundancy of the configuration. Further, the self-excited power conversion device 1 is not limited to the one configured with the six arms 4up to 4wm, and may be configured with any number of arms. For example, although the self-excited power conversion device 1 has been described as a configuration that converts DC power to three-phase AC power, a configuration that converts DC power to single-phase AC power may be used. In this case, a self-excited power converter that converts DC power into single-phase AC power with four arms can be configured.

  In the present embodiment, when the cells CL11 to CL64 are daisy chain connected through the transmission lines L1 and L2, they may be connected in any order. In the present embodiment, the loop-shaped transmission lines L1 and L2 are used. However, the number of loop-shaped transmission lines may be one, or three or more.

  Further, in the present embodiment, the data is transmitted from both directions to one loop transmission line L1, L2. However, the two loop transmission lines are duplexed and the two data are transmitted separately. You may make it the structure which transmits so that it may mutually turn to a path | route.

  The configuration of the cell CL is not limited to that shown in FIG. Any circuit may be used as long as it is a converter including a switching element and functions as a configuration of a self-excited power converter. For example, the cell CL may be a bidirectional chopper or a full bridge converter.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Self-excited power converter device, 2 ... DC power supply, 3 ... Control device, 4up, 4um, 4vp, 4vm, 4wp, 4wm ... Arm, 5u, 5v, 5w ... Reactor, 6u, 6v, 6w ... Interconnection reactor, 7u, 7v, 7w... AC system, CL11 to CL64... Cell, L1, L2.

Claims (4)

A plurality of arms in which a plurality of unit converters are connected in series;
A transmission line connected in a loop to serially communicate the plurality of unit converters;
A self-excited power conversion device comprising: data transmission means for transmitting two data to the transmission line so that the receiving order of the plurality of unit converters is opposite to each other. 2. The self-excited power conversion device according to claim 1, wherein the data transmission unit transmits the two data from one direction to the one transmission line. The self-excited power conversion device according to claim 1, wherein the data transmission unit transmits the two data separately to the two transmission paths. A method of manufacturing a self-excited power conversion device configured by a plurality of units connected in series with a plurality of unit converters, wherein the plurality of unit converters are configured to perform serial communication,
Including a plurality of unit converters connected in a loop through a transmission line in order to transmit two data so that the receiving order of the plurality of unit converters is opposite to each other. Manufacturing method of excitation type power converter.

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