JP2015220783A - Self-excited power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-excited power conversion device, in which a plurality of unit converters perform serial communication, with high operation continuity to the abnormality on a serial communication line.SOLUTION: A self-excited power conversion device 1 includes: cells C1-C8 connected in series; by the division of the cells C1-C8 into groups G1-G4, transmission lines LP1-LP4 for the serial communication of the cells C1-C8 on the basis of each group G1-G4; a control device 3 which outputs composed data DT which includes signals for controlling the cells C1-C8, respectively; and distributors 7up-7wm for distributing the data DT, output from control device 3, to the plurality of groups G1-G4.

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 transmission line, the trouble of continued operation of the self-excited power conversion device increases. For example, when the gate signal is serially communicated to all the cells with one line, if this one line becomes abnormal, it becomes impossible to communicate with all the cells. Therefore, the operation of the self-excited power converter cannot be continued.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a self-excited power conversion device having a high continuity of operation for an abnormality in a line for serial communication with a plurality of unit converters.

  A self-excited power conversion device according to an aspect of the present invention includes a plurality of unit converters connected in series and the plurality of unit converters divided into a plurality of groups, and the unit converters perform serial communication for each group. A plurality of transmission lines, a control unit that outputs combined data including signals for controlling the plurality of unit converters, and the combined data output from the control unit. Distribution means for distributing to groups.

  ADVANTAGE OF THE INVENTION According to this invention, the self-excited power converter device with a high driving | operation continuity with respect to the abnormality of the line | wire for the serial communication of a several unit converter and serial communication can be provided.

The block diagram which shows the structure of the self-excitation power converter device which concerns on the 1st Embodiment of this invention. The circuit diagram showing the circuit of the cell concerning a 1st embodiment. The structure figure which showed simply the structure of the data transmitted to each distributor from the control apparatus which concerns on 1st Embodiment. The block diagram which shows the structure of the self-excited power converter device which concerns on the 2nd Embodiment of this invention.

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

(First embodiment)
FIG. 1 is a configuration diagram showing a configuration of a self-excited power conversion device 1 according to a first 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, and distributors 7up, 7um, 7vp, 7vm, 7wp, 7wm. The self-excited power conversion device 1 supplies three-phase AC power to AC systems 8u, 8v, and 8w 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 communicates with distributors 7up to 7wm provided corresponding to the arms 4up to 4wm via the transmission lines L1, L2, L3, L4, L5 and L6. The transmission lines L1 to L6 are configured by optical fiber cables and repeaters. The control device 3 includes cells (unit converters) C1, C2, C3, C4, C5, C6, C7, and C8 that constitute the arms 4up to 4wm via transmission lines L1 to L6 and distributors 7up to 7wm. To control the power conversion circuit.

  A power conversion circuit including six arms 4up to 4wm converts DC power into three-phase AC power. Each arm 4up-4wm is comprised of eight cells C1-C8 connected in series. Each arm 4up-4wm is configured similarly. The U phase of the power conversion circuit includes an upper (positive side) arm 4up of the U phase and a lower (negative side) arm 4um of the U phase. The V phase of the power conversion circuit is configured by an upper (positive side) arm 4vp of the V phase and a lower (negative side) arm 4vm of the V phase. The W phase of the power conversion circuit includes an upper (positive side) arm 4wp of the W phase and a lower (negative side) arm 4wm of the W phase.

  FIG. 2 is a circuit diagram showing a circuit of the cell CL according to the present embodiment. The configuration of all the cells C1 to C8 is the same 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 by switching of the two switching elements SW1 and SW2.

  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 is a positive terminal of the cell CL. 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 cells C1 to C8 constituting each arm 4up to 4wm are divided into four groups G1, G2, G3 and G4. Each group G1 to G4 includes a minimum number of cells C1 to C8 that can output a normal voltage. The normal voltage is, for example, a rated voltage of the self-excited power conversion device 1 or a voltage requested from the AC systems 8u, 8v, 8w. Here, the minimum number is two. Each arm 4up-4wm functions normally if at least one of the four groups G1-G4 is normal. The cells C1 to C8 constituting each group G1 to G4 are daisy chain connected by loop transmission lines LP1 to LP4. The transmission lines LP1 to LP4 of the groups G1 to G4 of the arms 4up to 4wm are connected to distributors 7up to 7wm provided corresponding to the arms 4up to 4wm. The cells C1 to C8 of the groups G1 to G4 respectively perform serial communication.

  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 8u 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 intermediate point of reactor 5v is connected to the V phase of AC system 8v 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 8w through 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.

  Interconnection reactors 6u, 6v, and 6w are reactors that are provided for system interconnection with AC systems 8u, 8v, and 8w. The U-phase interconnecting reactor 6u is provided between the U-phase AC system 8u and the midpoint of the U-phase reactor 5u. The V-phase interconnection reactor 6v is provided between the V-phase AC system 8v and the midpoint of the V-phase reactor 5v. The W-phase interconnecting reactor 6w is provided between the W-phase AC system 8w and the intermediate point of the W-phase reactor 5w. A three-phase interconnection transformer may be provided instead of the three-phase interconnection reactors 6u, 6v, 6w.

  FIG. 3 is a structural diagram simply showing the structure of data DT transmitted from the control device 3 according to the present embodiment to the distributors 7up to 7wm. In the data DT, eight data DT1 to DT8 corresponding to the eight cells C1 to C8 connected to the distributors 7up to 7wm are synthesized and stored.

  The control device 3 transmits data DT to the respective transmission lines L1 to L6. The distributors 7up to 7wm transmit the data DT received from the control device 3 via the transmission lines L1 to L6 to the transmission lines LP1 to LP4 of the groups G1 to G4, respectively, and serialize in the groups G1 to G4. Communicate. Each of the cells C1 to C8 constituting each group G1 to G4 takes out data DT1 to DT8 corresponding to itself from the combined data DT received from the transmission lines LP1 to LP4. The gate signals are included in the data DT1 to DT8 taken out by the cells C1 to C8. Each of the cells C1 to C8 is driven by the extracted gate signal.

  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 LP1 to LP4 or cells C1 to C8) necessary for serial communication and all software.

  The cells C1 to C8 constituting each arm 4up to 4wm are divided into groups G1 to G4. Each of the groups G1 to G4 includes a minimum number of cells C1 to C8 necessary for continued operation as arms 4up to 4wm, respectively. The cells C1 to C8 perform serial communication for each of the groups G1 to G4. Therefore, each arm 4up-4wm operates normally if the line of at least one group G1-G4 is normal.

  According to this embodiment, the cells C1 to C8 constituting the arms 4up to 4wm are divided into groups G1 to G4 having the minimum number necessary for continued operation, and serial communication is performed for each of the divided groups G1 to G4. Thus, if the lines of at least one group G1 to G4 are normal in each arm 4up to 4wm, the self-excited power conversion device 1 can continue operation. Therefore, compared with the case where the control apparatus 3 performs serial communication with all the cells C1-C8, redundancy can be improved.

  Further, by providing distributors 7up to 7wm corresponding to the arms 4up to 4wm, the total length of all the optical fiber cables connecting the long distance from the control device 3 to the cells C1 to C8 is shortened. The redundancy of each arm 4up-4wm can be ensured. For example, the total length of all the optical fiber cables can be shortened as compared with the case where the control device 3 and each of the cells C1 to C8 are wired one-to-one.

(Second Embodiment)
FIG. 4 is a configuration diagram showing a configuration of a self-excited power conversion device 1A according to the second embodiment of the present invention.

  A self-excited power conversion device 1A is a distributor 7up, 7um, 7vp, 7vm, 7wp provided corresponding to each arm 4up-4wm in the self-excited power conversion device 1 according to the first embodiment shown in FIG. 7wm is replaced with distributors 7up1 to 7up4, 7um1 to 7um4, 7vp1 to 7vp4, 7vm1 to 7vm4, 7wp1 to 7wp4, 7wm1 to 7wm4 provided corresponding to the groups G1 to G4 of the arms 4up to 4wm, 3 is replaced with the control device 3A, and the transmission lines L1, L2, L3, L4, L5, and L6 are replaced with transmission lines L11 to L14, L21 to L24, L31 to L34, L41 to L44, L51 to L54, and L61 to L64. Is. Other points are the same as in the first embodiment.

  Here, since each arm 4up-4wm is comprised similarly, it mainly demonstrates the upper arm 4up of U phase, and abbreviate | omits description suitably about the other arms 4um-4wm.

  The U-phase upper arm 4up is provided with four distributors 7up1 to 7up4 for each of the four groups G1 to G4. Each of the distributors 7up1 to 7up4 is connected to the control device 3A via transmission lines L11 to L14, respectively. The transmission lines L11 to L14 are configured by optical fiber cables and repeaters.

  3 A of control apparatuses communicate with each cell C1, C2, C3, C4, C5, C6, C7, C8 which comprises the upper arm 4up of U phase via the transmission lines L11-L14 and the divider | distributors 7up1-7up4. . In other respects, the control device 3A is the same as the control device 3 according to the first embodiment.

  3 A of control apparatuses transmit data DT to each transmission line L11-L14. The distributors 7up1 to 7up4 transmit the data DT received from the control device 3A via the transmission lines L11 to L14 to the transmission lines LP1 to LP4 of the groups G1 to G4 respectively corresponding to the respective groups G1. Serial communication is performed at ~ G4. In other respects, similarly to the first embodiment, the cells C1 to C8 of the groups G1 to G4 are driven by the gate signal received from the control device 3A.

  Next, the continuity of operation for the line abnormality of the self-excited power conversion device 1A will be described.

  Since the cells C1 to C8 constituting each arm 4up to 4wm are divided into groups G1 to G4 as in the first embodiment, if the lines of at least one group G1 to G4 are normal, Works normally. Further, since the distributors 7up1 to 7wm4 are also provided for the groups G1 to G4, if any one of the distributors 7up1 to 7wm4 is normal, the arms 4up to 4wm operate normally.

  According to the present embodiment, in addition to the operational effects of the first embodiment, the distributors 7up1 to 7wm4 are provided in the groups G1 to G4 of the arms 4up to 4wm, so the redundancy of the distributors 7up1 to 7wm4 is increased. Can do.

  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.

  In each embodiment, each arm 4up-4wm may be composed of any number of cells CL, or may be divided into any number of groups G1-G4. For example, each of the arms 4up to 4wm may include cells CL that are not used during one cycle of the output voltage even in a normal state in order to ensure configuration redundancy.

  In each embodiment, the self-excited power conversion devices 1 and 1A are not limited to the configuration described above, and may have any configuration as long as there is a configuration in which a plurality of cells CL are connected in series. For example, the self-excited power converters 1 and 1A are not limited to those configured with six arms 4up to 4wm, and may be configured with any number of arms. For example, the self-excited power conversion device 1 or 1A has been described as a configuration that converts DC power to three-phase AC power, but 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.

  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, 7up, 7um, 7vp, 7vm, 7wp, 7wm ... distributor, 8u, 8v, 8w ... AC system, C1-C8 ... cell, G1-G4 ... group, L1-L6, LP1-LP4 ... transmission path

Claims (5)

A plurality of unit converters connected in series;
Dividing the plurality of unit converters into a plurality of groups, a plurality of transmission paths for serial communication of the unit converter for each group;
Control means for outputting synthesized data including a signal for controlling each of the plurality of unit converters;
A self-excited power conversion device comprising: distribution means for distributing the combined data output from the control means to the plurality of groups. The self-excited power conversion device according to claim 1, wherein the distribution unit is provided for each group. The self-excited power conversion device according to claim 1, further comprising a plurality of arms each configured by the plurality of unit converters. The self-excited power converter according to any one of claims 1 to 3, wherein the plurality of unit converters are divided into the plurality of groups by a minimum number necessary for continued operation. A control method of a self-excited power converter that controls a self-excited power converter comprising a plurality of unit converters connected in series,
Dividing the plurality of unit converters into a plurality of groups, the unit converter for each group serial communication,
Outputting synthesized data including a signal for controlling each of the plurality of unit converters from the control device;
A control method for a self-excited power conversion device, comprising: distributing the combined data output from the control device to the plurality of groups.

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