Power conversion device

Abstract

To provide a power conversion device which can suppress delay of control even when a communication system of a star type centering on a relay is adopted.SOLUTION: There is provided a power conversion device which comprises: a main circuit part having a plurality of converters; a relay connected with the plurality of converters; and a control device which controls an operation of the main circuit part by communicating with the plurality of converters via the relay and inputting control signals in the plurality of converters, wherein the control device acquires a plurality of pieces of information required for control from the plurality of converters, generates the control signals of the plurality of converters on the basis of the plurality of pieces of acquired information, updates the plurality of pieces of information, and makes a frequency of update of information with a high degree of importance higher than a frequency of update of information with a low degree of importance.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a power conversion device.

Background Art

[0002] A power conversion device including at least one of a main circuit unit that performs at least one of conversion from AC power to DC power and conversion from DC power to AC power, and a control device that controls the operation of the main circuit unit is known. In such a power conversion device, a main circuit unit having a multi-stage configuration in which a plurality of converters are connected in series has been used. A power conversion device including a main circuit unit having a multi-stage configuration is used, for example, in a DC power transmission system that converts AC power into DC power and transmits it.

[0003] Each converter includes a plurality of switching elements and a charge storage element connected in parallel to each switching element. Each converter controls the switching of each switching element based on a control signal input from the control device. Thereby, conversion from AC power to DC power or conversion from DC power to AC power is performed.

[0004] The control device acquires information necessary for control from each converter. In addition, the control device updates the information by periodically acquiring information necessary for control from each converter. The control device generates a control signal for each converter based on the acquired information, and controls the operation of each converter by transmitting the generated control signal to each converter. That is, the control device performs feedback control of each converter based on the information acquired from each converter. Thereby, more appropriate control according to the state of each converter can be performed. For example, the magnitude of the power output from the main circuit unit can be controlled to a more appropriate magnitude according to the command value, or the operation of a converter in which an abnormality has occurred can be stopped.

[0005] In such a power conversion device, a repeater is provided between the control device and each converter, and a star-type communication method centered on the repeater is adopted. The repeater is connected to the control device via a signal line and is also connected to a plurality of other converters via a plurality of other signal lines. The repeater transmits the control signal transmitted from the control device to the plurality of converters and transmits the signals transmitted from the plurality of converters to the control device. In such a configuration, the total length of the signal lines can be shortened compared to a configuration in which the control device and the plurality of converters are directly connected via a plurality of signal lines. Thereby, for example, cost reduction can be achieved.

[0006] However, when the star-type communication method as described above is adopted, when transmitting signals from each of the plurality of converters to the control device, it is necessary to shift the signals of the plurality of converters in time so that the signals of the plurality of converters do not overlap on the signal line between the repeater and the control device, and transmit them from the repeater to the control device. For this reason, the communication cycle becomes longer compared to a configuration in which the control device and the plurality of converters are directly connected via a plurality of signal lines. Therefore, it takes time until the control device updates the information necessary for control, and there is a possibility that a delay in control may occur.

[0007] For this reason, in a power conversion device, it is desired to be able to suppress a delay in control even when adopting a star-type communication method centered on a repeater.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] An embodiment provides a power conversion device capable of suppressing a delay in control even when adopting a star-type communication method centered on a repeater.

Means for Solving the Problem

[0010] According to an embodiment, a plurality of converters and a control device that transmits a control signal for controlling the plurality of converters The plurality of converters and the control device are connected to that relays communication between the plurality of converters and the control device a repeater , and the control device requests the plurality of converters to transmit information necessary for control, by sending a request signal periodically sending obtains information necessary for the control from a response signal to the request signal received from the plurality of converters, and generates the control signal for controlling the plurality of converters based on the plurality of pieces of information thus obtained The plurality of converters each of in response to receiving the request signal the response signal at a timing different from that of other converters send to to the control device and The information included in the response signal necessary for control is at least first information and second information having a lower weight than the first information set for the control of the converter weight importance exist , The transmission frequency of the response signal including only the first information is higher than the transmission frequency of the response signal including the first information and the second information A power conversion device is provided.

Advantages of the Invention

[0011] In this embodiment, a power conversion device capable of suppressing control delay is provided even when a star-type communication method centered on a repeater is adopted.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc. are not necessarily the same as the actual ones. Also, even when representing the same part, the dimensions and ratios may be represented differently in the drawings. In the present specification and each drawing, elements similar to those described above with respect to the previously shown drawings are denoted by the same reference numerals, and detailed descriptions thereof are omitted as appropriate.

[0014] (First Embodiment) FIG. 1 is a block diagram schematically showing the power conversion device according to the first embodiment. As shown in FIG. 1, the power conversion device 10 includes a main circuit section 20, a repeater 40, and a control device 50. The power conversion device 10 is connected to an AC power system 1 via AC terminals 21a to 21c. The power conversion device 10 is connected to the power system 1 via, for example, a transformer 2. The power system 1 can be configured to include, for example, a three-phase or single-phase 50 Hz or 60 Hz power source, load, and AC transmission line. The power conversion device 10 is connected to a DC circuit 3 via DC terminals 21d and 21e. The DC circuit 3 includes, for example, a DC transmission line or the like. Hereinafter, it is assumed that the power conversion device 10 is connected to a three-phase power system 1.

[0015] The power conversion device 10 is connected between the power system 1 and the DC circuit 3 and can perform bidirectional power conversion between AC and DC. However, the power conversion by the power conversion device 10 may be in only one direction, either from AC to DC or from DC to AC.

[0016] In the power conversion device 10, the control device 50 and the relay 40 are connected via the signal line 60 and transmit data to each other. The relay 40 and the main circuit section 20 are connected via the signal line 42 and transmit data to each other. That is, the control device 50 can transmit data to and receive data from the main circuit section 20 via the signal line 60, the relay 40, and the signal line 42.

[0017] The main circuit section 20 is installed on the insulating pedestal 26. The insulating pedestal 26, the relay 40, and the control device 50 are placed, for example, on the same installation surface 4. The insulating pedestal 26 is formed of an insulating material, and the main circuit section 20 is electrically insulated from the relay 40 and the control device 50. The installation surface 4 on which the insulating pedestal 26, the relay 40, and the control device 50 are placed has substantially the same potential, and they may be physically different surfaces. For example, the insulating pedestal 26 and the relay 40 may be placed on the floor surface of the control room on the second floor of the building, and the control device 50 may be placed on the floor surface of the first floor of the same building.

[0018] The main circuit section 20 includes a plurality of arms 22 corresponding to each phase of the three-phase AC. The arms 22 are connected in series between the DC terminals 21d and 21e.

[0019] Buffer reactors 24 are respectively connected in series to the arms 22 connected in series between the DC terminals 21d and 21e. The buffer reactors 24 suppress the flow of instantaneous short-circuit current between the upper and lower arms 22. The taps of the buffer reactors 24 are respectively connected to the AC terminals 21a to 21c.

[0020] Each arm 22 has a plurality of converters 30 connected in series. In the following description, it is assumed that M converters 30 are connected in series to one arm 22 (M is an integer of 2 or more). In each arm 22, the number of converters 30 connected in series is, for example, 100 or more. However, the number of converters 30 connected in series is not limited to this and may be any number.

[0021] The number of converters 30 provided in each arm 22 is substantially the same. For example, when a large number of converters 30 are connected, the number of converters 30 provided in each arm 22 may be different within a range that does not affect the operation of the main circuit section 20. For example, when 100 converters 30 are connected in series to one arm 22, the number of converters 30 provided in another arm 22 may differ by 1 to 2.

[0022] The repeater 40 is connected to the control device 50 via the signal line 60. The repeater 40 is connected to the converter 30 via the signal line 42. The repeater 40 distributes the control signal transmitted from the control device 50 to each of the plurality of converters 30 via the signal line 42 corresponding to the converter 30. Further, the repeater 40 transmits the signals transmitted from each of the plurality of converters 30 to the control device 50. The repeater 40, for example, combines the data of each signal transmitted from the plurality of converters 30 into the data of one signal, substantially making it serial data, and transmits it to the control device 50. The power conversion device 10 employs a star-type communication method centered on the repeater 40.

[0023] For example, optical communication is used for the communication between the control device 50 and each converter 30. The control signal transmitted from the control device 50 to each converter 30 and the signal transmitted from each converter 30 to the control device 50 are, for example, optical signals. The signal lines 42 and 60 are, for example, optical fiber cables. The repeater 40 is, for example, an optical distributor or a star coupler.

[0024] However, the communication between the control device 50 and each converter 30 does not necessarily have to be optical communication. The communication between the control device 50 and each converter 30 may be, for example, communication by an electrical signal. The repeater 40 is not limited to an optical distributor or a star coupler, and may be any member that can distribute and transmit the control signal from the control device 50 to each converter 30 and can combine the signals from each converter 30 and transmit them to the control device 50. In other words, the repeater 40 may be any member that enables the adoption of a star-type communication method centered on the repeater 40 in the communication between the control device 50 and each converter 30.

[0025] For example, only the communication between the repeater 40 and each converter 30 may be optical communication, and the communication between the repeater 40 and the control device 50 may be communication by an electrical signal. Conversely, only the communication between the repeater 40 and the control device 50 may be optical communication, and the communication between the repeater 40 and each converter 30 may be communication by an electrical signal. For example, when the power handled by each converter 30 is large, as described above, at least a part of the communication between the plurality of converters 30 and the control device 50 is preferably optical communication to electrically insulate the plurality of converters 30 from the control device 50.

[0026] The repeater 40 can be installed near the main circuit unit 20. Therefore, the signal line 42 can be made to have a length such that it can be laid within the main circuit unit 20. The control device 50 can be installed at a location sufficiently separated from the main circuit unit 20 and the repeater 40. For example, the control device 50 may be installed in a different building or floor from the installation locations of the repeater 40 and the main circuit unit 20. The length of the signal line 42 can be made sufficiently shorter than the length of the signal line 60. Thereby, for example, compared with the case where a plurality of signal lines 42 corresponding to the number of each converter 30 are directly connected to the control device 50, the total length of the signal lines can be shortened. Thereby, cost reduction can be achieved.

[0027] The power conversion device 10 includes, for example, a plurality of repeaters 40. For example, when the number of converters 30 provided in one arm 22 of the main circuit section 20 is 96, the power conversion device 10 includes six repeaters 40 for one arm 22. In this case, one repeater 40 is connected to 16 converters 30 via a signal line 42 and communicates with the 16 converters 30. In this case, the power conversion device 10 provides six repeaters 40 for each of the six arms 22 and includes a total of 36 repeaters 40.

[0028] The control device 50 has a plurality of communication ports (communication connection sections) and is connected to each of the plurality of repeaters 40 via a plurality of signal lines 60. Thereby, even when a plurality of repeaters 40 are provided, communication can be performed between the control device 50 and each converter 30.

[0029] However, the number of repeaters 40 and the number of converters 30 connected to one repeater 40 are not limited to the above and may be any number. For example, all the converters 30 provided in the main circuit section 20 may be connected to one repeater 40. The number of repeaters 40 may be appropriately set according to, for example, the number of signals that can be distributed in the repeater 40.

[0030] The control device 50 is connected to the repeater 40, communicates with a plurality of converters 30 via the repeater 40, and inputs a control signal to each of the plurality of converters 30, thereby controlling the operation of the main circuit section 20. Further, the control device 50 communicates with each converter 30 via the signal line 42, the repeater 40, and the signal line 60, thereby acquiring information necessary for control from each converter 30. The control device 50 updates the information by periodically acquiring information necessary for control from each converter 30.

[0031] The control device 50 controls the operations of the converters 30 by generating control signals for each converter 30 based on the acquired information and transmitting the generated control signals to each converter 30. That is, the control device 50 performs feedback control of each converter 30 based on the information acquired from each converter 30. Thereby, more appropriate control according to the state of each converter 30 can be performed. For example, the magnitude of the power output from the main circuit unit 20 can be controlled to a more appropriate magnitude according to the command value, or the operation of the converter 30 in which an abnormality has occurred can be stopped.

[0032] FIG. 2 is a block diagram schematically showing a converter according to the first embodiment. As shown in FIG. 2, the converter 30 has a pair of terminals 31a and 31b. The converter 30 is serially connected to other converters 30 or the like by the terminals 31a and 31b. The converter 30 includes a control circuit 32, a drive circuit 33, a conversion circuit 35, and a main circuit power supply unit 36.

[0033] The conversion circuit 35 includes a plurality of switching elements 35S1 and 35S2, diodes 35D1 and 35D2, and a charge storage element 35C. The switching elements 35S1 and 35S2 are connected in series. The diodes 35D1 and 35D2 are connected in anti-parallel to the switching elements 35S1 and 35S2, respectively. The charge storage element 35C is connected in parallel to the series circuit of the switching elements 35S1 and 35S2.

[0034] The conversion circuit 35 switches between an output state in which the voltage of the charge storage element 35C is output between the pair of terminals 31a and 31b by switching of the plurality of switching elements 35S1 and 35S2, a stop state in which the output of the voltage of the charge storage element 35C between the pair of terminals 31a and 31b is stopped, and a bypass state in which the pair of terminals 31a and 31b are made conductive.

[0035] In this example, by turning off the upper switching element 35S1 and turning on the lower switching element 35S2, the conversion circuit 35 can be put into a bypass state. The stop state is a state in which both the switching elements 35S1 and 35S2 are turned off. The stop state may also be referred to as, for example, a gate block state or the like.

[0036] The switching elements 35S1 and 35S2 are, for example, self-extinguishing semiconductor switches such as IGBTs (Insulated Gate Bipolar Transistors). The switching elements 35S1 and 35S2 are driven by drive signals supplied from the drive circuit 33 and charge and discharge the charge storage element 35C.

[0037] The conversion circuit 35 is not limited to a circuit having a half-bridge configuration as described above, and may be a circuit having a full-bridge configuration using four switching elements. The number of the plurality of switching elements of the conversion circuit 35 is not limited to two, and may be four or more.

[0038] The control circuit 32 receives the control signal transmitted from the control device 50 via the signal line 60, the repeater 40, and the signal line 42, generates a switching control signal for controlling the switching of the plurality of switching elements 35S1 and 35S2 based on the control signal, and inputs the generated switching control signal to the drive circuit 33.

[0039] The drive circuit 33 performs level conversion or the like on the switching control signal supplied from the control circuit 32, generates a drive signal for driving the switching elements 35S1 and 35S2 based on the switching control signal, and inputs the generated drive signal to the switching elements 35S1 and 35S2 of the conversion circuit 35 to switch the on / off states of the switching elements 35S1 and 35S2.

[0040] The main circuit power supply unit 36 receives power supply from the charge storage element 35C, converts it to an appropriate voltage, and supplies it to each part of the converter 30 such as the control circuit 32 and the drive circuit 33. Each part of the converter 30 operates based on the power supply from the main circuit power supply unit 36.

[0041] Figure 3 is an explanatory diagram schematically showing an example of signals transmitted from each converter to the control device. When the control device 50 acquires information necessary for control from each converter 30, it transmits a request signal for requesting the transmission of the necessary information to each converter 30 via the repeater 40. In response to the reception of the request signal from the control device 50, each converter 30 transmits the response signals SA1 to SAn shown in Figure 3 to the control device 50.

[0042] As shown in Figure 3, the response signals SA1 to SAn transmitted from each converter 30 to the control device 50 include, for example, a plurality of pieces of information. Also, the response signals SA1 to SAn are configured in a predetermined data structure (frame). The data structures of the response signals SA1 to SAn are substantially the same. Figure 3 exemplifies the case where each of the response signals SA1 to SAn has a data structure including four pieces of information, information A to information D.

[0043] The items of information A, information B, information C, and information D are the same in each of the response signals SA1 to SAn. Each converter 30 acquires its own information A to information D in response to the reception of the request signal, and transmits the acquired information A to information D to the control device 50 as the response signals SA1 to SAn.

[0044] The items of each piece of information are, for example, the voltage of the charge storage element 35C, the current flowing between the pair of terminals 31a and 31b (arm current), the presence or absence of a failure in the switching elements 35S1 and 35S2, etc. However, the number of pieces of information included in the response signals SA1 to SAn is not limited to four, and may be any number. Also, the information (items of information) included in the response signals SA1 to SAn is not limited to the above, and may be any information necessary for the control of each converter 30.

[0045] As shown in FIG. 3, the plurality of information included in the response signals SA1 to SAn is divided into first information that is highly important regarding the control of each converter 30 and second information that is less important than the first information. In other words, the first information is information that needs to be updated at high speed. In other words, the second information is information that does not necessarily need to be updated at high speed.

[0046] In FIG. 3, an example is illustrated where only the information D of the first converter 30 (converter 1) is the first information and each of the other information is the second information. Hereinafter, the plurality of converters 30 may be referred to as converter 1 to converter N. Converter 1 includes the first information in the response signal SA1, and the other converters 2 to N do not include the first information in the response signals SA2 to SAn. The converters 1 to N are, for example, a plurality of converters 30 connected to a single repeater 40.

[0047] The first information is, for example, information regarding the current (arm current) flowing between a pair of terminals 31a and 31b. The second information is, for example, information regarding the voltage of the charge storage element 35C and information regarding the presence or absence of a failure in the switching elements 35S1 and 35S2. However, the first information is not limited to the above, and may be any information that is highly important and needs to be updated at high speed in the control device 50. The second information is not limited to the above, and may be any information that is less important than the first information and does not necessarily need to be updated at high speed in the control device 50.

[0048] FIG. 4 is an explanatory diagram schematically showing an example of the operation of the power conversion device according to the first embodiment. FIG. 4 schematically shows an example of the request signals SR1 to SRn transmitted from the control device 50 to the repeater 40, the request signals SR1 to SRn distributed and transmitted from the repeater 40 to each converter 30, the response signals SA1 to SAn transmitted from each converter 30 to the repeater 40, and the received signal SA received by the control device 50 from the repeater 40.

[0049] As shown in FIG. 4, when the control device 50 acquires information necessary for control from each converter 30, first, a request signal SR1 for requesting transmission of necessary information is sent to the repeater 40 for the converter 1 including the first information. When the repeater 40 receives the request signal SR1 from the control device 50, it distributes and transmits the received request signal SR1 to each converter 30.

[0050] When each converter 30 receives the request signal SR1, it determines whether the received request signal SR1 is for itself. Among the plurality of converters 30, the converter 1 determines that the request signal SR1 is for itself, and in response to the reception of the request signal SR1, it sends a response signal SA1 including information necessary for control to the repeater 40. The other converters 30 determine that the request signal SR1 is not for themselves and do not send the response signals SA2 to SAn. When the repeater 40 receives the response signal SA1 from the converter 1, it sends the received response signal SA1 to the control device 50.

[0051] When the control device 50 receives the response signal SA1 from the converter 1, in response to the reception of the response signal SA1, it then sends a request signal SR2 for requesting transmission of necessary information to the repeater 40 for the converter 2. The converter 2 sends a response signal SA2 including information necessary for control to the repeater 40 in response to the reception of the request signal SR2.

[0052] The control device 50 repeats the same process hereinafter. As shown in FIG. 4, it sequentially acquires the information of each converter 30 in the order of converter 1 → converter 2 → converter 1 → converter 3 → converter 1 → converter 4 → ··· converter 1 → converter N.

[0053] In a star - type communication system centered around the repeater 40, when transmitting the response signals SA1 to SAn from each of the plurality of converters 30 to the control device 50, it is necessary to shift the response signals SA1 to SAn of the plurality of converters 30 in time so that they do not overlap on the signal line 60 between the repeater 40 and the control device 50 and then transmit them from the repeater 40 to the control device 50.

[0054] In this example, the control device 50 generates a plurality of request signals SR1 to SRn corresponding to each of the converters 30, and by shifting the plurality of request signals SR1 to SRn in time and transmitting them to each converter 30, each converter 30 transmits response signals SA1 to SAn by shifting them in time based on the request signals SR1 to SRn. Thereby, it is possible to suppress the overlapping of the response signals SA1 to SAn of the plurality of converters 30 on the signal line 60 between the repeater 40 and the control device 50.

[0055] As described above, the plurality of converters 30 transmit response signals SA1 to SAn including a plurality of pieces of information necessary for control to the control device 50 in response to the reception of the request signals SR1 to SRn, and also shift the respective response signals SA1 to SAn of the plurality of converters 30 in time based on the request signals SR1 to SRn and transmit them to the control device 50.

[0056] The control device 50 acquires a plurality of pieces of information necessary for control from the plurality of converters 30 by receiving the response signals SA1 to SAn, generates control signals for the plurality of converters 30 based on the acquired plurality of pieces of information, and periodically transmits the request signals SR1 to SRn and periodically acquires the plurality of pieces of information, thereby updating the plurality of pieces of information.

[0057] Then, the plurality of converters 30 shift the response signals SA1 to SAn in time based on the request signals SR1 to SRn and transmit them, and increase the transmission frequency of the response signal from the converter 30 including the first information to the control device 50 in the response signal compared to the transmission frequency of the response signal from the converter 30 not including the first information to the control device 50 in the response signal. Thereby, the control device 50 increases the update frequency of the first information with high importance compared to the update frequency of the second information with low importance.

[0058] FIG. 5 is an explanatory diagram schematically showing an example of the reference operation of the power conversion device. FIG. 5 schematically shows an example of a request signal SR transmitted from the control device 50 to the repeater 40, a request signal SR distributed and transmitted from the repeater 40 to each converter 30, response signals SA1 to SAn transmitted from each converter 30 to the repeater 40, and a received signal SA received by the control device 50 from the repeater 40. Note that FIG. 3 illustrates a reference operation of the control device 50 when adopting a star-type communication method centered on the repeater 40, and does not represent the operation of the control device 50 according to the present embodiment.

[0059] As shown in FIG. 5, in the reference operation, when the control device 50 acquires information necessary for control from each converter 30, the control device 50 transmits a request signal SR requesting the transmission of the necessary information to each converter 30 to the repeater 40. When the repeater 40 receives the request signal SR from the control device 50, the repeater 40 distributes and transmits the received request signal SR to each converter 30.

[0060] In response to the reception of the request signal SR, each converter 30 transmits response signals SA1 to SAn including information necessary for control to the repeater 40. At this time, as described above, in the star-type communication method centered on the repeater 40, it is necessary to transmit the response signals SA1 to SAn of the plurality of converters 30 to the control device 50 from the repeater 40 with a time shift. FIG. 5 shows an example in which the response signals SA1 to SAn are transmitted from the repeater 40 to the control device 50 with a shift at regular intervals T.

[0061] For example, a plurality of converters 30 have a transmission delay adjustment function for transmitting the response signals SA1 to SAn with a time shift. For example, the first converter 30 transmits the response signal SA1 to the repeater 40 immediately in response to the reception of the request signal SR, the second converter 30 transmits the response signal SA2 to the repeater 40 T seconds after the reception of the request signal SR, the third converter 30 transmits the response signal SA3 to the repeater 40 2T seconds after the reception of the request signal SR, and so on. The same process is repeated, and the Nth converter 30 transmits the response signal SAn to the repeater 40 (N - 1)T seconds after the reception of the request signal SR. Thereby, the overlap of the response signals SA1 to SAn on the signal line 60 between the repeater 40 and the control device 50 can be suppressed, and the information of the response signals SA1 to SAn can be appropriately received by the control device 50 as the received signal SA.

[0062] Note that the transmission delay adjustment function may be provided in the repeater 40, for example. For example, each converter 30 transmits the response signals SA1 to SAn to the repeater 40 immediately in response to the reception of the request signal SR. After substantially simultaneously receiving the response signals SA1 to SAn from each converter 30, the repeater 40 transmits the received response signals SA1 to SAn to the control device 50 with a time shift. Also in this case, the overlap of the response signals SA1 to SAn on the signal line 60 can be suppressed in the same manner as above.

[0063] Also, the transmission delay adjustment function may be provided in the control device 50, for example. For example, as shown in FIG. 4, a plurality of request signals SR1 to SRn corresponding to each of the converters 30 are generated, and the plurality of request signals SR1 to SRn are sequentially transmitted to each converter 30 while being time-shifted. Each converter 30 transmits the response signals SA1 to SAn to the repeater 40 in response to the reception of the request signals SR1 to SRn corresponding to itself. Also in this case, the overlap of the response signals SA1 to SAn on the signal line 60 can be suppressed in the same manner as above.

[0064] Thus, the transmission delay adjustment function may be provided in each converter 30, may be provided in the repeater 40, or may be provided in the control device 50. The configuration in which the response signals SA1 to SAn of the plurality of converters 30 are time-shifted and transmitted from the repeater 40 to the control device 50 can be any configuration that can appropriately suppress the overlap of the response signals SA1 to SAn on the signal line 60.

[0065] However, in the configuration in which the response signals SA1 to SAn of the plurality of converters 30 are time-shifted and transmitted from the repeater 40 to the control device 50 as in the example shown in FIG. 5, compared with a configuration in which the control device 50 and the plurality of converters 30 are directly connected via a plurality of signal lines, the communication cycle becomes longer.

[0066] For example, when the response signal SA1 of the converter 1 contains first information with high importance, and as shown in FIG. 5, the response signals SA1 to SAn are transmitted from the repeater 40 to the control device 50 with a shift of a fixed interval of T seconds, the update frequency of the first information with high importance of the converter 1 becomes every n×T seconds, and there is a possibility that a delay in control may occur.

[0067] On the other hand, in the power conversion device 10 according to the present embodiment, as shown in FIG. 4, the plurality of converters 30 time-shift and transmit the response signals SA1 to SAn based on the request signals SR1 to SRn, and the frequency of transmitting the response signal from the converter 30 including the first information to the control device 50 in the response signal is made higher than the frequency of transmitting the response signal from the converter 30 not including the first information to the control device 50. Thereby, in the control device 50, the update frequency of the first information with high importance is made higher than the update frequency of the second information with low importance. Thereby, even when adopting a star-type communication method centered on the repeater 40, a delay in control can be suppressed.

[0068] For example, when protecting the main circuit unit 20 based on the first information, the power conversion device 10 can be quickly stopped in response to the update of the first information, and the safety of the power conversion device 10 can be improved. In addition, control commands, feedback signals, etc. can be transmitted at high speed as the first information, and the operability of the power conversion device 10 can also be improved.

[0069] Note that in the example shown in FIG. 4, the response signal from the converter 30 that does not include the first information in the response signal is transmitted to the control device 50 at a frequency of once every two times, such as converter 1 → converter 2 → converter 1 → converter 3 → converter 1 → converter 4 → ··· converter 1 → converter N.

[0070] Not limited to this, for example, the response signal from the converter 30 that does not include the first information in the response signal may be transmitted to the control device 50 at a frequency of once every three times, such as converter 1 → converter 1 → converter 2 → converter 1 → converter 1 → converter 3 → converter 1 → converter 1 → converter 4 → ··· converter 1 → converter 1 → converter N. Thereby, the update frequency of the first information with high importance can be made higher.

[0071] Conversely, for example, the response signal from the converter 30 that includes the first information in the response signal may be transmitted to the control device 50 at a frequency of once every three times, such as converter 1 → converter 2 → converter 3 → converter 1 → converter 4 → converter 5 → ··· converter 1 → converter (N - 1) → converter N. In this case, it is possible to suppress the situation where the update frequency of the second information becomes too low while increasing the update frequency of the first information with high importance. The update frequency of the first information with high importance is not limited to the above and may be any frequency.

[0072] The frequency of transmitting a response signal from the converter 30 including the first information to the control device 50 may be determined according to, for example, the number of a plurality of converters 30 connected to the repeater 40. For example, after sending each response signal of the plurality of converters 30 connected to the repeater 40, the response signal is transmitted from the converter 30 including the first information to the control device 50. In this case, it is possible to further suppress the situation where the update frequency of the second information becomes too low while increasing the update frequency of the first information with high importance.

[0073] The frequency of transmitting a response signal from the converter 30 including the first information to the control device 50 may be set according to, for example, the sampling period of the first information. For example, every time the first information is newly acquired by a measuring device or the like, the response signal is transmitted from the converter 30 including the first information to the control device 50. In other words, the frequency of transmitting a response signal from the converter 30 including the first information to the control device 50 is set to be equal to or greater than the sampling period of the first information. Thereby, it is possible to suppress repeatedly transmitting the first information with the same content to the control device 50 and unnecessarily increasing the update frequency.

[0074] Also, in the example shown in FIG. 4, by transmitting the request signals SR1 to SRn individually set for each converter 30 from the control device 50, the frequency of transmitting a response signal from the converter 30 including the first information to the control device 50 is made higher than the frequency of transmitting a response signal from the converter 30 not including the first information to the control device 50.

[0075] Not limited to this, for example, the transmission timing of the response signal is preset for each converter 30, a common request signal SR (see FIG. 5) is transmitted from the control device 50 to each converter 30, and each converter 30 transmits a response signal at the preset transmission timing in response to the reception of the request signal SR. Thus, the frequency of transmitting a response signal from the converter 30 including the first information to the control device 50 may be made higher than the frequency of transmitting a response signal from the converter 30 not including the first information to the control device 50.

[0076] In the above embodiment, a plurality of pieces of information are divided into two pieces of information with different importance levels of the first information and the second information. In other words, two levels of importance are set for the plurality of pieces of information. Without being limited to this, the importance level may be set to three or more levels, and the plurality of pieces of information may be divided into three or more pieces of information. The plurality of pieces of information included in the response signal may be divided according to a plurality of levels of importance set for the control of the plurality of converters 30. The control device 50 may make the update frequency of the information with a higher importance level among the plurality of pieces of information higher than the update frequency of the information with a lower importance level.

[0077] For example, the plurality of converters 30 transmit the response signal with a time shift based on the request signal, and the higher the importance level of the information included in the response signal of the converter 30, the higher the transmission frequency of the response signal to the control device 50. In this way, in the control device 50, the update frequency of the information with a higher importance level may be made higher than the update frequency of the information with a lower importance level.

[0078] For example, when the plurality of pieces of information are divided into three pieces of information, namely the first information to the third information, the transmission frequency of the response signal of the converter 30 including the first information with the highest importance level is made the highest, and the transmission frequency of the response signal of the converter 30 including the second information with a higher importance level than the third information is made higher than the transmission frequency of the response signal of the converter 30 including the third information, and the transmission frequency of the response signal of the converter 30 including only the third information is made the lowest. Thereby, even when the plurality of pieces of information are divided into three, in the control device 50, the update frequency of the information with a higher importance level can be made higher than the update frequency of the information with a lower importance level.

[0079] Further, for example, the transmission frequency of the response signal from the converter 30 including the information with a higher importance level in the response signal to the control device 50 may be set according to the sampling period of the information with a higher importance level.

[0080] (Second Embodiment) FIG. 6 is an explanatory diagram schematically showing an example of a response signal according to the second embodiment. As shown in FIG. 6, in this example, the data configurations of the response signals SA1 to SAn are changed according to each of the plurality of converters 30. Note that components that are substantially the same in function and configuration as those in the above embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0081] Each converter 30, for example, makes the number of information of the response signal not including the first information smaller than the number of information of the response signal including the first information. In other words, each converter 30, for example, makes the frame length of the response signal not including the first information shorter than the frame length of the response signal including the first information.

[0082] For example, in a plurality of converters 30 connected in series to the same arm 22, the information regarding the current (arm current) flowing between a pair of terminals 31a and 31b is substantially the same. Therefore, the information regarding the arm current is included only in the response signal including the first information, and the information regarding the arm current is not included in the response signal not including the first information. For example, in the example shown in FIG. 6, the information regarding the arm current is included only in the response signal SA1, and the information regarding the arm current is not included in the response signals SA2 to SAn. Thereby, the frame length of the response signal not including the first information can be made shorter than the frame length of the response signal including the first information.

[0083] In this case, the items of information A, the items of information B, and the items of information C do not necessarily have to be the same in each of the response signals SA1 to SAn. The plurality of information included in the response signal may be arbitrarily set corresponding to each of the converters 30.

[0084] FIG. 7 is an explanatory diagram schematically showing an example of the operation of the power conversion device according to the second embodiment. FIG. 7 schematically shows an example of a request signal SR transmitted from the control device 50 to the relay device 40, a request signal SR distributed and transmitted from the relay device 40 to each converter 30, response signals SA1 to SAn transmitted from each converter 30 to the relay device 40, and a reception signal SA received by the control device 50 from the relay device 40.

[0085] As shown in Fig. 7, when the control device 50 acquires information necessary for control from each converter 30, the control device 50 transmits a request signal SR for requesting the transmission of necessary information to each converter 30 to the repeater 40. When receiving the request signal SR from the control device 50, the repeater 40 distributes and transmits the received request signal SR to each converter 30.

[0086] In response to the reception of the request signal SR, each converter 30 transmits response signals SA1 to SAn including information necessary for control to the repeater 40. At this time, each converter 30 transmits the response signals SA1 to SAn to the control device 50 from the repeater 40 with a time shift by transmitting the response signals SA1 to SAn to the control device 50 at time intervals corresponding to the data configuration (frame length) of the response signals SA1 to SAn instead of at constant intervals.

[0087] For example, an interval T1 is set for the response signal SA1 of the converter 1 including the first information, and an interval T2 shorter than the interval T1 is set for the response signals SA2 to SAn of the converters 2 to N not including the first information.

[0088] As shown in Fig. 7, the converter 1 immediately transmits the response signal SA1 to the repeater 40 in response to the reception of the request signal SR. The converter 2 transmits the response signal SA2 to the repeater 40 after T1 seconds from the reception of the request signal SR. The converter 3 transmits the response signal SA3 to the repeater 40 after T1 + T2 seconds from the reception of the request signal SR. The converter 4 transmits the response signal SA4 to the repeater 40 after T1 + 2 × T2 seconds from the reception of the request signal SR. Hereinafter, the same process is repeated, and the converter N transmits the response signal SAn to the repeater 40 after T1 + (N - 2)T2 seconds from the reception of the request signal SR.

[0089] Thereby, even when the time intervals corresponding to the data configurations of the response signals SA1 to SAn are set, overlapping of the response signals SA1 to SAn on the signal line 60 between the repeater 40 and the control device 50 can be suppressed, and the information of the response signals SA1 to SAn can be appropriately received by the control device 50 as the received signal SA.

[0090] In this way, the data configurations of the response signals SA1 to SAn are changed according to each of the plurality of converters 30, and the number of information of the response signals not including the first information is made smaller than the number of information of the response signals including the first information. In this case, the communication cycle can be shortened as compared with the case where the data configurations of the response signals SA1 to SAn are the same. Thereby, the update frequency of the first information with high importance can be increased as compared with the case where the data configurations of the response signals SA1 to SAn are the same. Therefore, also in the present embodiment, similar to the above-described embodiment, when adopting a star-type communication method centered on the repeater 40, the control delay can be suppressed.

[0091] Also, since the communication cycle can be shortened, for example, the number of converters 30 connected to the repeater 40 can be increased. Thereby, for example, the number of repeaters 40, the number of signal lines 60 between the repeater 40 and the control device 50, and the number of communication ports of the control device 50 can be reduced.

[0092] For example, when the number of converters 30 provided in one arm 22 of the main circuit unit 20 is 96, and the number of converters 30 connectable to one repeater 40 increases from 16 to 32, the number of repeaters 40 for one arm 22 can be reduced from 6 to 3. Accordingly, the number of signal lines 60 and the number of communication ports of the control device 50 can also be reduced. Furthermore, reduction of the installation location of the repeater 40 can also be achieved. Therefore, for example, miniaturization of the power conversion device 10 and reduction of the manufacturing cost can be achieved.

[0093] In the example shown in FIG. 7, the control device 50 transmits a common request signal SR to each converter 30, and each converter 30 transmits a response signal at a preset transmission timing in response to the reception of the request signal SR, so that the response signals SA1 to SAn are transmitted to the control device 50 at time intervals corresponding to the data configuration. However, it is not limited to this. For example, the control device 50 may transmit individually set request signals SR1 to SRn to each converter 30, and transmit the response signals SA1 to SAn in response to the reception of the corresponding request signals SR1 to SRn, so that the response signals SA1 to SAn are transmitted to the control device 50 at time intervals corresponding to the data configuration.

[0094] Also in this example, the importance level may be set to three or more levels, and the plurality of pieces of information may be divided into three or more pieces of information. The plurality of converters 30 may make the number of pieces of information in the response signal not including the information with high importance level less than the number of pieces of information in the response signal including the information with high importance level.

[0095] For example, when the plurality of pieces of information are divided into three pieces of information, i.e., the first information to the third information, the number of pieces of information included in the response signal of the converter 30 including the most important first information is made the largest, the number of pieces of information included in the response signal of the converter 30 including the second information with a higher importance level than the third information is made larger than the number of pieces of information included in the response signal of the converter 30 including the third information, and the number of pieces of information included in the response signal of the converter 30 including only the third information may be made the smallest.

[0096] (Third Embodiment) FIG. 8 is an explanatory diagram schematically showing an example of a response signal according to the third embodiment. As shown in FIG. 8, in this example, the converter 1 including the first information in the response signal transmits to the control device 50 a response signal SA1a including a plurality of pieces of information A to D and a response signal SA1b including only the information D which is the first information.

[0097] The control device 50 transmits a request signal SR1a that requests the converter 1 to transmit all of the plurality of pieces of information A to D, and transmits a request signal SR1b that requests the converter 1 to transmit only the information D which is the first information. The converter 1 transmits a response signal SA1a in response to the reception of the request signal SR1a, and transmits a response signal SA1b in response to the reception of the request signal SR1b.

[0098] For example, as shown in FIG. 4, when the control device 50 performs the transmission of the response signal from the converter 1 including the first information to the control device 50 at a frequency of once every two times, the control device 50 transmits the request signal SR1a in the transmission of the first request signal, and transmits the request signal SR1b in the transmission of the request signal after the second time.

[0099] In this example, each converter 30 transmits the response signals SA1a, SA1b, SA2 to SAn in the order of, for example, converter 1 (information A to D) → converter 2 → converter 1 (only information D) → converter 3 → converter 1 (only information D) → converter 4 → ··· converter 1 (only information D) → converter N.

[0100] In this way, in this example, the converter 1 that includes the first information in the response signal transmits the response signal SA1a including the plurality of pieces of information A to D and the response signal SA1b including only the information D which is the first information to the control device 50, and makes the frequency of the transmission of the response signal SA1b including only the first information higher than the frequency of the transmission of the response signal SA1a including the plurality of pieces of information A to D. As a result, in this example, in the control device 50, the update frequency of the first information with high importance can be made higher than the update frequency of the second information with low importance. Thereby, even when adopting a star - type communication method centered on the repeater 40, the control delay can be further suppressed.

[0101] Note that the frequency of transmitting the response signal SA1b containing only the first information is not limited to the above, and may be any frequency as described in the first embodiment above. Further, the transmission of the response signal SA1b containing only the first information is not limited to the configuration of transmitting in response to the reception of the request signal SR1b from the control device 50, and may be a configuration of transmitting at a predetermined transmission timing.

[0102] Also, in this example as well, the importance level may be set to three levels or more, and the plurality of information may be divided into three or more pieces of information. The converter 30 that includes information with a high importance level in the response signal transmits a response signal including a plurality of information and a response signal including only information with a high importance level to the control device 50, and may set the frequency of transmitting the response signal including only information with a high importance level to be higher than the frequency of transmitting the response signal including a plurality of information.

[0103] For example, when the plurality of information is divided into three pieces of information, i.e., first information to third information, the frequency of transmitting the response signal including only the first information with the highest importance level may be the highest, and the frequency of transmitting the response signal including only the second information may be higher than the frequency of transmitting the response signal including a plurality of information.

[0104] (Fourth Embodiment) FIG. 9 is a block diagram schematically showing a power conversion device according to the fourth embodiment. As shown in FIG. 9, the power conversion device 10a further includes a dedicated signal line 62 that enables direct communication between the converter 30 that includes the first information in the response signal and the control device 50, separately from the communication paths of the signal line 42, the repeater 40, and the signal line 60.

[0105] The control device 50 acquires information necessary for control from each converter 30 by a star-type communication method centered on the repeater 40 by the operation shown in FIG. 5, for example, and communicates with the converter 30 that includes the first information in the response signal via the dedicated signal line 62, thereby acquiring the first information at a higher frequency from the converter 30 that includes the first information in the response signal than through the communication via the repeater 40.

[0106] Accordingly, also in the power conversion device 10a according to the present embodiment, even when adopting a star-type communication method centered on the repeater 40 with the update frequency of the first information with high importance being higher than the update frequency of the second information with low importance, it is possible to suppress a control delay. Note that the frequency of acquiring the first information from the converter 30 including the first information in the response signal via the dedicated signal line 62 may be any frequency higher than the communication via the repeater 40.

[0107] Note that, in this example, the transmission delay adjustment function may be provided in the repeater 40. A configuration in which a plurality of converters 30 shift the respective response signals of the plurality of converters 30 in time based on a request signal and transmit them to the control device 50 may be a configuration in which the respective response signals of the plurality of converters 30 are shifted in time in the repeater 40.

[0108] Also in this example, the importance may be set to three or more levels, and the plurality of information may be divided into three or more pieces of information. The control device 50 communicates with a plurality of converters 30 via the repeater 40 to periodically acquire a plurality of information, and communicates with the converter 30 including information with high importance in the response signal via the dedicated signal line 62, and acquires information with high importance from the converter 30 including information with high importance in the response signal at a frequency higher than the communication via the repeater 40, so that the update frequency of the information with high importance may be made higher than the update frequency of the information with low importance.

[0109] For example, when the plurality of information is divided into three pieces of information, i.e., first information to third information, the update frequency of the most important first information may be made the highest by communication via the dedicated signal line 62, and the update frequency of the second information may be made higher than the update frequency of the third information.

[0110] In each of the above embodiments, the main circuit section 20 having a plurality of converters 30 connected in series is shown. Each of the above embodiments is not limited to this, and may be applied to a case where each converter 30 and the control device 50 perform star-type communication centered on the repeater 40 in a main circuit section having a plurality of converters 30 connected in parallel.

[0111] As described above, several embodiments of the present invention have been explained. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and its equivalents. In addition, the above-described embodiments can be implemented in combination with each other.

Description of Reference Numerals

[0112] 1 Power system, 2 Transformer, 3 DC circuit, 4 Installation surface, 10, 10a Power conversion device, 20 Main circuit section, 22 Arm, 24 Buffer reactor, 26 Insulating pedestal, 30 Converter, 32 Control circuit, 33 Drive circuit, 35 Conversion circuit, 35C Charge storage element, 35D Diode, 35S1, 35S2 Switching element, 36 Main circuit power supply section, 40 Repeater, 42 Signal line, 50 Control device, 60 Signal line, 62 Dedicated signal line

Claims

1. A plurality of converters; A control device that transmits a control signal for controlling the plurality of converters; A repeater connected to the plurality of converters and the control device, and relaying communication between the plurality of converters and the control device; Comprising: The control device periodically transmits a request signal requesting transmission of information necessary for control to the plurality of converters, acquires the information necessary for control from a response signal to the request signal received from the plurality of converters, and generates the control signal for controlling the plurality of converters based on the plurality of acquired information; Each of the plurality of converters, in response to receiving the request signal, transmits the response signal to the control device at a timing different from that of other converters; The information necessary for control included in the response signal includes at least first information and second information having a lower importance for converter control than the first information, and the transmission frequency of the response signal including only the first information is higher than the transmission frequency of the response signal including the first information and the second information. A power conversion device.

2. When the converter has the first information and the second information, the converter generates a response signal including only the first information and a response signal including the first information and the second information. The power conversion device according to claim 1.

3. The first information is information regarding a current flowing between two terminals for connecting the converter to other converters; The second information is at least one of information regarding the presence or absence of a failure of a switching element constituting the converter and information regarding the voltage of a charge storage element constituting the converter. The power conversion device according to claim 1.

4. At least part of the communication between the plurality of converters and the control device is optical communication. The power conversion device according to any one of claims 1 to 3.

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