JP2018023230A - Electric power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power converter with a simple configuration capable of continuing the operation even when a cell part gets failed.SOLUTION: An electric power converter 100 includes plural converter cell parts 10 which are connected in series to each other for each phase. When any one of the plural converter cells 10 which are connected in series to each other for each phase gets failed, plural output terminal parts 14 in the failed converter cells 10 are short-circuited, and the voltage of the electric power output from the converter cells 10 is adjusted. With this, the voltage of the electric power output from the plural converter cells 10 which are connected in series to each other is adjusted to a generally same value.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a power conversion device, and particularly to a power conversion device including a plurality of cell units connected in series for each phase.

  Conventionally, a power converter provided with a plurality of cells connected in series for each phase is known (see, for example, Patent Document 1).

  The power conversion device described in Patent Document 1 includes a plurality of unit power converters. The plurality of unit power converters are connected in series with each other (hereinafter referred to as a unit power converter group) for each phase (U phase, V phase, and W phase). Further, one end (output terminal portion) of the unit power converter is connected to a load, and the other end is connected to a neutral point. In addition, when the unit power converter fails, one end and the other end of the unit power converter that has failed are short-circuited, so that the unit power converter that has failed is bypassed.

  The power conversion device described in Patent Document 1 includes a spare unit power converter. When the unit power converter fails, the failed unit power converter is switched to a spare unit power converter. That is, when one end and the other end of a unit power converter that has failed (for example, a U-phase unit power converter) are short-circuited (bypassed), the unit power converter group of the U-phase The unit power converter is disconnected. A spare unit power converter is connected in series to the U-phase unit power converter group. As a result, the number of unit power converters included in the U-phase unit power converter group and the number of unit power converters included in the V-phase and W-phase unit power converter groups are the same. As a result, since the power (voltage) output from the unit power converter group of each phase can be made substantially the same, the power conversion device can be continuously operated.

JP 2012-147613 A

  However, in the power conversion device described in Patent Document 1, a spare unit power converter is provided to continue operation of the power conversion device when the unit power converter (cell unit) fails. Therefore, there is a problem that the configuration of the power conversion device becomes complicated.

  The present invention has been made in order to solve the above-described problems, and one object of the present invention is to continue operation while suppressing the complexity of the configuration even when the cell portion fails. It is providing the power converter device which can be performed.

  In order to achieve the above object, a power converter according to one aspect of the present invention includes a cell unit that converts alternating current into direct current and includes a plurality of output terminal units, and the cell unit is connected in series for each phase. When one of the plurality of cell units connected in series and connected in series for each phase fails, a plurality of output terminal portions of the failed cell unit are short-circuited and output from the cell unit By adjusting the voltage of the generated power, the voltages of the power output from the plurality of cell units connected in series for each phase are adjusted to be substantially the same.

  In the power conversion device according to one aspect of the present invention, as described above, when any one of the plurality of cell units connected in series for each phase fails, the plurality of output terminals of the failed cell unit The part is short-circuited. Then, by adjusting the voltage of the power output from the cell unit, the voltage of the power output from the plurality of cell units connected in series for each phase is adjusted to be substantially the same. . As a result, the power voltage output from the plurality of cell units is adjusted so as to be substantially the same without separately providing a spare cell unit, so that the power conversion device is suppressed while preventing the configuration from becoming complicated. Can continue driving.

  In the power conversion device according to the above aspect, preferably, when any one of the plurality of cell units connected in series for each phase fails, the plurality of output terminal units of the failed cell unit are short-circuited. In addition, the output voltage of the cell part of the phase including the failed cell part is relatively increased with respect to the output voltage of the cell part of the non-failed phase, so that each phase is connected in series. The power voltages output from the plurality of cell units are adjusted so as to be substantially the same. Here, when a cell part fails, the number of cell parts (cell parts that do not fail) that can output voltage decreases in the phase including the failed cell part. Therefore, it is easy to connect each phase in series by increasing the output voltage of the cell part of the phase including the failed cell part relative to the output voltage of the cell part of the non-failed phase. The voltage of the power output from the plurality of cell units can be adjusted to be substantially the same.

  In this case, preferably, the power conversion device is connected to the power system via the interconnection reactor, and when performing advance compensation for the power system, the output voltage of the phase cell unit including the failed cell unit is obtained. In addition to the first voltage based on the rated voltage of the cell unit and the interconnected reactor, the output voltage of the cell unit of the non-failed phase is made smaller than the first voltage, so that each phase is connected in series. The voltage of the electric power output from the several cell part connected to is adjusted so that it may become substantially the same mutually. If comprised in this way, the output voltage of the cell part of the phase containing the failed cell part is made into the 1st voltage comparatively large. As a result, the voltage that can be output from the power conversion device can be made relatively large, so that advance compensation can be performed in a relatively wide range. Lead compensation means that the reactive power is consumed when the voltage of the power converter becomes larger than the voltage of the power system and a current of 90 degrees advances from the power system side toward the power converter. Means. Note that reactive power means power that reciprocates between a power source and a load and that is not consumed by the load. The reactive power is a factor such as voltage fluctuation. That is, by adjusting (consuming) reactive power, the voltage of the power system can be stabilized.

  In the power conversion device in which the output voltage of the cell portion of the failed phase is relatively increased, preferably, when delay compensation is performed for the power system, or when compensation is not performed for the power system, A plurality of cells connected in series for each phase by making the output voltage of the cell portion of the phase including the failed cell portion and the output voltage of the cell portion of the non-failed phase smaller than the first voltage. The voltage of the power output from the cell part is adjusted so as to be substantially the same. With this configuration, the output voltage of the cell portion of the phase including the failed cell portion and the output voltage of the cell portion of the non-failed phase are set to a relatively small voltage that is lower than the first voltage. The Thereby, delay compensation can be easily performed (or not compensated). The delay compensation means that the reactive power is consumed when the voltage of the power conversion device becomes smaller than the voltage of the power system and a 90-degree delay current flows from the power system side toward the power conversion device. Means.

  In the power conversion device according to the above aspect, preferably, when any one of the plurality of cell units connected in series for each phase fails, the plurality of output terminal units of the failed cell unit are short-circuited. In addition, the power output from the plurality of cell units connected in series for each phase without short-circuiting the plurality of output terminal units of the plurality of cell units connected in series of the non-failed phase Are adjusted to be substantially the same. If comprised in this way, since the several output terminal part of the cell part of the phase which is not out of order is not short-circuited (bypassed), it can suppress that the number of cell parts which can output a voltage decreases. Thereby, it can suppress that the output voltage of a power converter device falls.

  In the power conversion device according to the one aspect described above, preferably, the power conversion device is connected to the power system via the interconnection reactor, and the withstand voltage of the cell unit is based on the rated voltage of the cell unit and the interconnection reactor. When the voltage is higher than the first voltage, the second voltage higher than the first voltage is output from the cell unit. If comprised in this way, since the 2nd voltage larger than a 1st voltage is output from a cell part, the output voltage of a power converter device can be increased. As a result, when the power conversion device is used for the advance compensation for the power system, the range that can be compensated can be expanded.

  According to the present invention, as described above, even when the cell unit fails, the operation of the power conversion device can be continued while suppressing the configuration from becoming complicated.

It is a figure which shows the structure of the power converter device by 1st and 2nd embodiment of this invention. It is a block diagram for demonstrating operation | movement of the power converter device at the normal time. It is a figure for demonstrating the specification of the power converter device at the time of normal. It is a figure for demonstrating the compensation possible range of a power converter device. It is a block diagram for demonstrating operation | movement of the power converter device in the case of performing lead compensation (45%) when one converter cell part fails. It is a block diagram for demonstrating operation | movement of the power converter device when compensation is not performed when one converter cell part fails. It is a block diagram for demonstrating operation | movement of the power converter device in case delay compensation (-100%) is performed when one converter cell part fails. It is a figure for demonstrating the specification of the power converter device by 2nd Embodiment of this invention. It is a figure for demonstrating the compensation possible range of the power converter device by 2nd Embodiment of this invention. It is a block diagram which shows the structure of the power converter device by the modification of 1st and 2nd embodiment of this invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

[First Embodiment]
With reference to FIG. 1, the structure of the power converter device 100 by 1st Embodiment is demonstrated. The power conversion device 100 is connected to the power system 200 and has a function as a reactive power compensator (STATCOM: Static Synchronous Compensator) that compensates for reactive power of the power system 200.

(Configuration of power converter)
The power conversion device 100 includes a converter cell unit 10 (unit converter cell unit) including a plurality of output terminal units 14 while converting alternating current into direct current. A plurality of converter cell units 10 are connected in series for each phase (U phase, V phase, and V phase). Specifically, 20 converter cell units 10 are connected in series for each phase (U phase, V phase, and V phase). The converter cell unit 10 is an example of the “cell unit” in the claims.

  In addition, the 20 converter cell units 10 connected in series for each phase (U phase, V phase, and V phase) are star-connected. That is, 20 U-phase converter cell units 10 (U1 to U20, hereinafter referred to as U-phase converter cell group 20) and 20 V-phase converter cell units 10 (V1 to V20, hereinafter referred to as V-phase converter cell group). 30) and 20 W-phase converter cell units 10 (W1 to W20, hereinafter referred to as W-phase converter cell group 40) are connected at a neutral point N. Note that the star connection has a relatively simple current flow as compared with the delta connection and the like, and thus has excellent expandability and redundancy.

  In addition, the power conversion apparatus 100 includes a grid reactor 50. The power conversion apparatus 100 is connected to the power system 200 via the interconnection reactor 50. Specifically, U-phase converter cell group 20, V-phase converter cell group 30, and W-phase converter cell group 40 are each connected to electric power system 200 through interconnection reactor 50.

  In addition, the power conversion device 100 includes a control unit 60. The control unit 60 is configured to control the overall operation of the power conversion apparatus 100.

(Converter cell configuration)
As shown in FIG. 1, the converter cell unit 10 includes a DC capacitor 11. The converter cell unit 10 includes a semiconductor switch group 13 including two semiconductor switches 12 connected in series with each other. The semiconductor switch 12 is composed of, for example, an IGBT (Insulated Gate Bipolar Transistor). Further, two converter switches 13 are provided in one converter cell unit 10. The DC capacitor 11 and the two semiconductor switch groups 13 are connected in parallel to each other.

  In addition, the converter cell unit 10 includes two output terminal units 14. The output terminal unit 14 is connected between the emitter and collector of two semiconductor switches 12 connected in series with each other.

  In addition, the converter cell unit 10 includes a short-circuit switch unit 15 for short-circuiting the two output terminal units 14. When the short-circuit switch unit 15 is turned on, the two output terminal units 14 are short-circuited. That is, the converter cell unit 10 is bypassed. Further, ON / OFF of the short-circuit switch unit 15 is controlled by the control unit 60. Moreover, the control part 60 is comprised so that the two output terminal parts 14 of the converter cell part 10 which failed may be short-circuited.

  Specifically, when any of the plurality of converter cell units 10 connected in series for each phase fails, the control unit 60 sets the plurality of output terminal units 14 of the failed converter cell unit 10. Short circuit. For example, when one converter cell unit 10 (for example, converter cell unit U1) in U-phase converter cell group 20 fails, two output terminal units 14 of failed converter cell unit U1 are short-circuited. That is, in U-phase converter cell group 20, converter cell unit U1 is bypassed. As a result, in the U-phase converter cell group 20, power is output by the remaining 19 converter cell units 10 (U2 to U20) connected in series to each other except the failed converter cell unit U1.

(Operation of power converter)
Next, the operation of the power conversion device 100 will be described with reference to FIGS. The operation of the power conversion device 100 is controlled by the control unit 60.

<Normal operation>
First, the normal operation of the power conversion device 100 will be described with reference to FIGS.

  As shown in FIG. 2, two output terminal portions of the converter cell unit 10 are normally used (when none of the plurality of converter cell units 10 connected in series for each phase has failed). 14 is not bypassed. That is, power can be output from all converter cell units 10.

  As shown in FIG. 3, it is assumed that the system voltage (phase voltage) of the power system 200 is 20 kV. As described above, 20 converter cell units 10 are connected for each phase. Further, it is assumed that the rated voltage of one converter cell unit 10 is 1.0 kV. That is, the total rated voltage (= 1.0 kV × 20) output from the 20 converter cell units 10 for each phase is substantially equal to the system voltage (20 kV) of the power system 200.

  Here, the power conversion device 100 includes the interconnection reactor 50. Therefore, the voltage output from the twenty converter cell units 10 to the power system 200 is reduced by the amount that includes the interconnected reactor 50. Therefore, the converter cell unit 10 is configured to be able to output a maximum output voltage of 1.1 kV (= 1.0 kV × 1.1), assuming that the percent impedance of the interconnection reactor 50 is 10%. The maximum output voltage is an example of the “first voltage” in the claims.

  That is, as shown in FIG. 4, from each of U-phase converter cell group 20, V-phase converter cell group 30 and W-phase converter cell group 40 each including 20 converter cell units 10, 22.00 kV ( = 1.1 kV × 20) (maximum output phase voltage) can be output. In this case, the rated ratio is 110.0%. The rated ratio is a percentage of the maximum output phase voltage with respect to the total rated voltage (20 kV = 1.0 × 20) of the rated voltages of the 20 converter cell units 10. That is, the maximum output phase voltage divided by the rated voltage is multiplied by 100 (22.00 kV / 20 kV × 100).

  Here, when the output voltage from each of the U-phase converter cell group 20, the V-phase converter cell group 30 and the W-phase converter cell group 40 is 22 kV, which is higher than the voltage (20 kV) of the power system 200, 100 % Lead compensation is possible. That is, when the advance compensation is performed for the power system 200 (delay reactive power of the power system 200), the power conversion device 100 functions as a capacitor in a pseudo manner.

  The output voltage from each of the U-phase converter cell group 20, the V-phase converter cell group 30, and the W-phase converter cell group 40 is 18 kV (= 20 kV × (1-0.1)), and the power system 200 When the voltage is lower than the voltage (20 kV), -100% delay compensation is possible. That is, when delay compensation is performed for power system 200 (advanced reactive power of power system 200), power conversion device 100 functions as a pseudo-reactor.

  Then, the control unit 60 monitors the voltage of the electric power system 200 to reduce the fluctuation of the voltage of the electric power system 200 by performing advance compensation or lag compensation for the fluctuation of the voltage of the electric power system 200.

<Operation at failure (45% lead compensation)>
Next, an operation at the time of failure (in the case of advance compensation) will be described with reference to FIG. Specifically, a description will be given of the case where the maximum 45% advance compensation is performed in the range in which advance compensation can be performed when one converter cell unit 10 fails.

  As shown in FIG. 5, it is assumed that converter cell unit U1 in U-phase converter cell group 20 has failed. In this case, the two output terminal portions 14 of the failed converter cell unit U1 are short-circuited. That is, in U-phase converter cell group 20, converter cell unit U1 is bypassed.

  Here, in 1st Embodiment, the voltage of the electric power output from the several converter cell part 10 connected in series for every phase is adjusted by adjusting the voltage of the electric power output from the converter cell part 10. Are adjusted to be substantially the same. That is, the voltage output from the U-phase converter cell group 20 with the converter cell unit U1 bypassed, the voltage output from the V-phase converter cell group 30 and the voltage output from the W-phase converter cell group 40 Are adjusted to be substantially the same. Specifically, when one of the plurality of converter cell units 10 connected in series for each phase (here, the converter cell unit U1) fails, the phase including the failed converter cell unit U1 ( Here, the output voltage of converter cell unit 10 in the U phase is relatively increased with respect to the output voltage of converter cell unit 10 in the phases that are not faulty (here, V phase and W phase).

  Specifically, in the first embodiment, when the advance compensation is performed on the electric power system 200, the output voltage of the converter cell unit 10 in the phase (U phase) including the failed converter cell unit U1 is set to By setting the maximum output voltage based on the rated voltage and the interconnected reactor 50 and reducing the output voltage of the converter cell unit 10 in the non-failed phase (V phase and V phase) below the maximum output voltage, The voltage of the electric power output from the several converter cell part 10 connected in series for every phase is adjusted so that it may become substantially the same mutually.

  That is, the output voltage output from each converter cell unit 10 other than the bypassed converter cell unit U1 in the U-phase converter cell group 20 is set to the maximum output voltage (1.1 kV). Further, the output voltage output from each of converter cell units 10 of V-phase converter cell group 30 is adjusted to 1.045 kV, which is smaller than the maximum output voltage (1.1 kV). Further, the output voltage output from each of converter cell units 10 of W-phase converter cell group 40 is adjusted to 1.045 kV, which is smaller than the maximum output voltage (1.1 kV).

  As a result, the total output voltage output from the U-phase converter cell unit 10 other than the bypassed converter cell unit U1 is 20.90 kV (= 1.1 kV × 19). Further, the total output voltage output from the V-phase converter cell group 30 is 20.90 kV (= 1.45 kV × 20). Further, the total output voltage output from the W-phase converter cell group 40 is 20.90 kV (= 1.045 kV × 20). Thus, the voltage of the electric power output from the several converter cell part 10 connected in series for every phase is adjusted so that it may become mutually substantially the same.

  That is, in the first embodiment, when any of the plurality of converter cell units 10 connected in series for each phase fails, the two output terminal units 14 of the failed converter cell unit U1 are short-circuited. On the other hand, the two output terminal portions 14 of the plurality of converter cell units 10 connected in series of the non-failed phases (V phase and W phase) are connected in series for each phase without short-circuiting. The voltage of the power output from the plurality of converter cell units 10 is adjusted to be substantially the same.

  Here, as shown in FIG. 4, the total output voltage (maximum output phase voltage) output from each of the U-phase converter cell group 20, the V-phase converter cell group 30 and the W-phase converter cell group 40 is 20. In the case of 90 kV, the rated ratio is 104.5% (= 20.90 kV / 20 kV × 100). That is, the output voltage (20.90 kV) output from each of the U-phase converter cell group 20, the V-phase converter cell group 30 and the W-phase converter cell group 40 is less than the system voltage (20 kV) of the power system 200. Increased by .9 kV, leading to compensation. Furthermore, 45% (= 0.9 kV / 2 kV × 100) lead compensation is performed with respect to the maximum lead compensation (2 kV = 22.00-20) when there is no failed converter cell unit 10 (normal time). It will be in the state.

  In the above description, the case where the maximum 45% advance compensation is performed in the advance compensation range has been described. When the advance compensation is made smaller than 45%, it is outputted from each of the U-phase converter cell group 20, the V-phase converter cell group 30 and the W-phase converter cell group 40 in accordance with the magnitude of the reactive power to be compensated. The voltage is adjusted.

<Operation at failure (no compensation)>
Next, the operation at the time of failure (no compensation) will be described with reference to FIG.

  In the first embodiment, when the power system 200 is not compensated, the output voltage of the converter cell unit 10 in the phase (here, the U phase) including the failed converter cell unit 10 and the non-failed phase A plurality of converter cell units 10 connected in series for each phase by making the output voltage of converter cell unit 10 (here, V phase and W phase) smaller than the maximum output voltage (1.1 kV). Are adjusted so that the voltages of the electric power output from each other are substantially the same.

  Specifically, the two output terminal portions 14 of the failed converter cell unit U1 are short-circuited. That is, in U-phase converter cell group 20, converter cell unit U1 is bypassed. In addition, the output voltage output from the converter cell unit 10 other than the converter cell unit U1 in the U-phase converter cell group 20 is set to 20/19 kV, which is smaller than the maximum output voltage (1.1 kV).

  In addition, the output voltage output from the converter cell unit 10 of each of the V-phase converter cell group 30 and the W-phase converter cell group 40 in the non-failed phase (here, V phase and W phase) is the maximum output voltage ( 1.1 kV), which is smaller than 1.0 kV. As a result, the total output voltage output from the U-phase converter cell group 20 is 20 kV (= 20/19 kV × 19). The total output voltage output from each of the V-phase converter cell group 30 and the W-phase converter cell group 40 is 20 kV (= 1.0 kV × 20). Thus, the voltage of the electric power output from the several converter cell part 10 connected in series for every phase is adjusted so that it may become mutually substantially the same. Further, the output voltage (20 kV) output from each of the U-phase converter cell group 20, the V-phase converter cell group 30 and the W-phase converter cell group 40 becomes equal to the system voltage (20 kV) of the power system 200, and compensation is performed. It will be in the state which has not gone.

<Operation at failure (-100% delay compensation)>
Next, the operation at the time of failure (in the case of delay compensation) will be described with reference to FIG. Specifically, the case where the maximum -100% delay compensation is performed in the delay compensation range will be described.

  In the first embodiment, when delay compensation is performed on the electric power system 200, the output voltage of the converter cell unit 10 of the phase (here, U phase) including the failed converter cell unit 10 and the non-failed phase A plurality of converter cell units 10 connected in series for each phase by making the output voltage of converter cell unit 10 (here, V phase and W phase) smaller than the maximum output voltage (1.1 kV). Are adjusted so that the voltages of the electric power output from each other are substantially the same.

  Specifically, the two output terminal portions 14 of the failed converter cell unit U1 are short-circuited. That is, in U-phase converter cell group 20, converter cell unit U1 is bypassed. Further, the output voltage output from the converter cell unit 10 other than the converter cell unit U1 in the U-phase converter cell group 20 is set to 18/19 kV which is smaller than the maximum output voltage (1.1 kV).

  In addition, the output voltage output from the converter cell unit 10 of each of the V-phase converter cell group 30 and the W-phase converter cell group 40 in the non-failed phase (here, V phase and W phase) is the maximum output voltage ( 1.1 kV), which is smaller than 0.9 kV. As a result, the total output voltage output from the U-phase converter cell group 20 is 18 kV (= 18/19 kV × 19). The total output voltage output from each of the V-phase converter cell group 30 and the W-phase converter cell group 40 is 18 kV (= 0.9 kV × 20). Thus, the voltage of the electric power output from the several converter cell part 10 connected in series for every phase is adjusted so that it may become mutually substantially the same. That is, the output voltage (18 kV) output from each of the U-phase converter cell group 20, the V-phase converter cell group 30 and the W-phase converter cell group 40 is smaller than the system voltage (20 kV) of the power system 200, − 100% delay compensation is performed.

  In the above description, the case where the maximum -100% delay compensation is performed in the delay compensation range has been described. When delay compensation is made smaller than −100% (closer to the positive side), the U-phase converter cell group 20, the V-phase converter cell group 30 and the W-phase converter cell group are matched to the magnitude of reactive power to be compensated. The voltage output from each of 40 is adjusted.

  As shown in FIG. 4, when two converter cell units 10 fail (when the number of converter cell units 10 per phase is 18), the maximum output phase voltage is 19.80 kV, The ratio is 99.0%. In this case, the compensation range is -10% to -100%. When three converter cell units 10 fail (when the number of converter cell units 10 per phase is 17), the maximum output phase voltage is 18.70 kV and the rated ratio is 93.5%. It becomes. In this case, the range that can be compensated is -65% to -100%. When four converter cell units 10 fail (when the number of converter cell units 10 per phase is 16), the maximum output phase voltage is 17.6 kV and the rated ratio is 88.5%. It becomes. In this case, the maximum output phase voltage becomes smaller than the output voltage (18 kV) of the power conversion device 100 when performing -100% delay compensation, and the power conversion device 100 cannot be linked to the power system 200.

(Effect of 1st Embodiment)
In the first embodiment, the following effects can be obtained.

  In the first embodiment, as described above, when any one of the plurality of converter cell units 10 connected in series for each phase fails, the plurality of output terminal units 14 of the failed converter cell unit 10 are used. Is short-circuited. And by adjusting the voltage of the power output from the converter cell unit 10, the voltage of the power output from the plurality of converter cell units 10 connected in series for each phase is substantially the same. It has been adjusted. As a result, the voltage of the power output from the plurality of converter cell units 10 is adjusted to be substantially the same without separately providing a spare converter cell unit 10, thereby suppressing the complexity of the configuration. However, the operation of the power conversion device 100 can be continued.

  Further, in the first embodiment, as described above, when any one of the plurality of converter cell units 10 connected in series for each phase fails, the plurality of output terminals of the failed converter cell unit 10 When the unit 14 is short-circuited, the output voltage of the converter cell unit 10 of the phase including the failed converter cell unit 10 is relatively increased with respect to the output voltage of the converter cell unit 10 of the non-failed phase. The voltage of the power output from the plurality of converter cell units 10 connected in series for each phase is adjusted to be substantially the same. Here, when the converter cell unit 10 fails, the number of converter cell units 10 (non-failed converter cell units 10) capable of outputting a voltage in the phase including the failed converter cell unit 10 decreases. Therefore, by making the output voltage of the converter cell unit 10 of the phase including the failed converter cell unit 10 relatively larger than the output voltage of the converter cell unit 10 of the non-failed phase, each phase can be easily obtained. The voltage of the electric power output from the several converter cell part 10 connected in series for every can be adjusted substantially mutually.

  In the first embodiment, as described above, when the advance compensation is performed for the power system 200, the output voltage of the converter cell unit 10 of the phase including the failed converter cell unit 10 is converted to the rating of the converter cell unit 10. In addition to the maximum output voltage based on the voltage and the interconnected reactor 50, the output voltage of the converter cell unit 10 of the non-failed phase is made smaller than the maximum output voltage, so that each phase is connected in series. The voltage of the power output from the plurality of converter cell units 10 is adjusted to be substantially the same. As a result, the output voltage of the converter cell unit 10 of the phase including the failed converter cell unit 10 is set to a relatively large maximum output voltage. As a result, the voltage that can be output from the power conversion apparatus 100 can be made relatively large, so that advance compensation can be performed in a relatively wide range. The advance compensation means that the power of the power conversion device 100 becomes larger than the voltage of the power system 200 and a current progressing 90 degrees from the power system 200 side to the power conversion device 100 flows. It means being consumed. Note that reactive power means power that reciprocates between a power source and a load and that is not consumed by the load. The reactive power is a factor such as voltage fluctuation. That is, the voltage of the power system 200 can be stabilized by adjusting (consuming) the reactive power.

  In the first embodiment, as described above, when delay compensation is performed on the power system 200 or when compensation is not performed on the power system 200, the phase including the converter cell unit 10 that has failed is corrected. A plurality of converter cell units 10 connected in series for each phase by making the output voltage of converter cell unit 10 and the output voltage of converter cell unit 10 of the non-failed phase smaller than the maximum output voltage. Are adjusted so that the voltages of the electric power output from each other are substantially the same. Thereby, the output voltage of the converter cell unit 10 of the phase including the failed converter cell unit 10 and the output voltage of the converter cell unit 10 of the non-failed phase are relatively small and smaller than the maximum output voltage. To be. Thereby, delay compensation can be easily performed (or not compensated). The delay compensation means that the voltage of the power conversion device 100 is smaller than the voltage of the power system 200 and a 90-degree delay current flows from the power system 200 side toward the power conversion device 100, so that the delayed reactive power is reduced. It means being consumed.

  Further, in the first embodiment, as described above, when any one of the plurality of converter cell units 10 connected in series for each phase fails, the plurality of output terminals of the failed converter cell unit 10 The part 14 is short-circuited, and the plurality of output terminal parts 14 of the plurality of converter cell parts 10 that are connected in series with a non-failed phase are connected in series for each phase without being short-circuited. The voltage of the electric power output from the converter cell unit 10 is adjusted to be substantially the same. Thereby, since the several output terminal part 14 of the converter cell part 10 of the phase which is not out of order is not short-circuited (bypassed), it can suppress that the number of the converter cell parts 10 which can output a voltage decreases. Thereby, it can suppress that the output voltage of the power converter device 100 falls.

[Second Embodiment]
Next, with reference to FIG. 1, FIG. 8, and FIG. 9, the power converter device 101 by 2nd Embodiment is demonstrated. In the power conversion device 101 according to the second embodiment, the withstand voltage of the converter cell unit 110 is larger than the maximum output voltage. In addition, the structure of the power converter device 101 (refer FIG. 1) by 2nd Embodiment is the same as that of the said 1st Embodiment.

  As shown in FIG. 8, in the power conversion device 101, when the withstand voltage of the converter cell unit 110 is larger than the maximum output voltage based on the rated voltage of the converter cell unit 110 and the interconnection reactor 50, A large maximum possible output voltage is output from the converter cell unit 110. Specifically, the maximum output voltage of the converter cell unit 110 based on the rated voltage (1.0 kV) of the converter cell unit 110 and the interconnection reactor 50 having a percent impedance of 10% is 1.1 kV (= 1). 0.0 kV × 1.1). The maximum output possible voltage is an example of the “second voltage” in the claims. The converter cell unit 110 is an example of the “cell unit” in the claims.

  Here, the voltage that can be output from the converter cell unit 110 is mainly determined by the DC capacitor 11 (see FIG. 1) and the breakdown voltage of the semiconductor switch 12. Thereby, when the withstand voltage of DC capacitor 11 and semiconductor switch 12 is relatively high, the voltage that can be output from converter cell unit 110 also increases. For example, when the breakdown voltage is 3% higher than the maximum output voltage (1.1 kV), the maximum voltage (maximum output possible voltage) that can be output from the converter cell unit 110 is 1.133 kV (= 1.1 kV). × 1.1 × 1.03).

  Thus, as shown in FIG. 9, when there is no failure in converter cell unit 110, the maximum output phase voltage is 22.66 kV and the rated ratio is 113.3%. Further, the compensation range is 100% to -100%. When one converter cell unit 110 fails, the maximum output phase voltage is 21.53 kV (= 1.133 kV × 19), and the rated ratio is 107.6%. Further, the compensation range is 76% to -100%. That is, in the second embodiment, the range that can be compensated is expanded as compared with the first embodiment (the range that can be compensated is 45% to −100%).

  Similarly, when two or three converter cell units 110 fail, the compensation range is expanded.

  In the case where four converter cell units 110 fail, the power converter 100 cannot be connected to the power system 200 in the first embodiment, whereas the second embodiment can be compensated. Becomes −94% to −100%, and the power conversion apparatus 101 can be linked to the power system 200. When five or more converter cell units 110 fail, the power conversion device 101 cannot be connected to the power system 200.

(Effect of 2nd Embodiment)
In the second embodiment, the following effects can be obtained.

  In the second embodiment, as described above, when the withstand voltage of the converter cell unit 110 is larger than the maximum output voltage based on the rated voltage of the converter cell unit 110 and the interconnection reactor 50, the maximum greater than the maximum output voltage. Outputtable voltage is output from converter cell unit 110. Thereby, since the maximum output possible voltage larger than the maximum output voltage is output from the converter cell part 110, the output voltage of the power converter device 101 can be increased. As a result, when the power conversion device 101 is used for the advance compensation for the power system 200, the range that can be compensated can be expanded.

  The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

[Modification]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of claims for patent, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first and second embodiments, the example in which the power conversion device of the present invention is applied to the reactive power conversion device (STATCOM) has been described, but the present invention is not limited to this. For example, you may apply the power converter device of this invention to a DC power transmission system (HVDC: high-voltage direct current).

  In the first and second embodiments, a plurality of converter cell units (U-phase converter cell group, V-phase converter cell group, and W-phase converter cell group) connected in series for each phase are Although an example of star connection is shown, the present invention is not limited to this. For example, like a power converter 120 according to a modification shown in FIG. 10, a plurality of converter cell units 121 (U-phase converter cell group 122a, V-phase converter cell group 122b, and The W-phase converter cell group 122c) may be delta-connected. Thereby, since a circulating current flows in the delta connection, the negative phase reactive power can be adjusted by controlling the circulating current. The converter cell unit 121 is an example of the “cell unit” in the claims.

  In the first and second embodiments described above, when any of the plurality of converter cell units connected in series for each phase fails (for example, the U-phase converter cell unit fails), Although the example which does not short-circuit the several output terminal part of the several converter cell part connected in series of the phase (V phase and W phase) which is not carried out was shown, this invention is not limited to this. For example, when one U-phase converter cell part fails, a plurality of output terminal parts of one failed U-phase converter cell part are short-circuited, and one non-failed V-phase converter cell part and failure A plurality of output terminal portions of one converter cell portion of the W phase that is not performed may be short-circuited. And by outputting the same voltage from all the converter cell parts, the voltage of the electric power output from the several converter cell part connected in series for every phase can mutually be made substantially the same.

  Moreover, in the said 1st and 2nd embodiment, although shown about the example in which 20 converter cell parts were connected in series for every phase, this invention is not limited to this. In the present invention, a number of converter cell units other than 20 units may be connected in series for each phase.

  Moreover, in the said 1st and 2nd embodiment, although shown about the example whose percent impedance of a connection reactor is 10%, this invention is not limited to this. For example, the percentage impedance of the interconnection reactor may be a value other than 10%.

  Moreover, in the said 2nd Embodiment, although the proof pressure of the converter cell part showed about 3% higher than the maximum output voltage of the converter cell part, it showed this invention, This invention is not limited to this. For example, the withstand voltage of the converter cell unit may be higher by% other than 3% with respect to the maximum output voltage of the converter cell unit.

10, 110, 121 Converter cell part (cell part)
DESCRIPTION OF SYMBOLS 15 Output terminal part 50 Interconnection reactor 100,101,120 Power converter 200 Power system

Claims (6)

In addition to converting alternating current to direct current, it has a cell portion including a plurality of output terminal portions,
A plurality of the cell units are connected in series for each phase, and if any of the plurality of cell units connected in series for each phase fails, the plurality of the cell units that have failed The output terminal portion is short-circuited, and by adjusting the voltage of the power output from the cell portion, the voltage of the power output from the plurality of cell portions connected in series for each phase is mutually A power converter that is adjusted to be substantially the same.   When any one of the plurality of cell units connected in series for each phase fails, the plurality of output terminal units of the failed cell unit are short-circuited and include the failed cell unit Output from the plurality of cell units connected in series for each phase by increasing the output voltage of the cell unit of the phase relative to the output voltage of the cell unit of the non-failed phase The power conversion device according to claim 1, wherein the voltages of the generated power are adjusted to be substantially the same. The power conversion device is connected to the power system via a grid reactor,
When the lead compensation is performed for the power system, the output voltage of the cell unit in the phase including the failed cell unit is set to the first voltage based on the rated voltage of the cell unit and the interconnection reactor. At the same time, by making the output voltage of the cell portion of the non-failed phase smaller than the first voltage, the voltage of the power output from the plurality of cell portions connected in series for each phase is The power conversion device according to claim 2, which is adjusted to be substantially the same as each other.   When delay compensation is performed on the power system, or when compensation is not performed on the power system, the output voltage of the cell unit in the phase including the failed cell unit, and the non-failed phase By making the output voltage of the cell part of the plurality of cell parts smaller than the first voltage, the voltage of the power output from the plurality of cell parts connected in series for each phase is substantially the same. The power converter according to claim 3, wherein the power converter is adjusted.   When any of the plurality of cell units connected in series for each phase fails, the plurality of output terminal units of the failed cell unit are short-circuited, and a series of non-failed phases The plurality of output terminal portions of the plurality of cell portions connected to each other are not short-circuited, and the voltages of power output from the plurality of cell portions connected in series for each phase are substantially the same. The power converter according to any one of claims 1 to 4, wherein the power converter is adjusted so as to be. The power conversion device is connected to the power system via a grid reactor,
When the withstand voltage of the cell unit is higher than the first voltage based on the rated voltage of the cell unit and the interconnection reactor, a second voltage higher than the first voltage is output from the cell unit. The power conversion device according to claim 1, configured as described above.

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