DC power transmission control device, DC power transmission control method

Abstract

To easily and surely perform recovery processing of a DC power transmission system.SOLUTION: DC power transmission control devices 20A, 20B are provided in a first control sequence 2A and a second control sequence 2B in a DC power transmission system 100 and perform control of the DC power transmission system 100 according to a control command input from an operation command device 1. In the DC power transmission control devices 20A, 20B, an in-sequence matching signal for matching the control state of the own control sequence with the control state of the other control sequence is output, and it is determined whether or not the own control sequence is being deblocked by using the in-sequence matching signal. Collation between the control state of the own control sequence and the control state of the other control sequence is executed by using the determination result, and it is determined whether or not the own control sequence satisfies a sequence return condition on the basis of the result of collation. When it is determined that the own control sequence satisfies the sequence return condition, a sequence return signal for returning the own control sequence to control of the DC power transmission system 100 is output to the operation command device 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus and method for controlling DC power transmission.

Background Art

[0002] In recent years, high-voltage direct current (HVDC) power transmission using high-voltage direct current has attracted attention. In such HVDC power transmission, compared with conventional AC power transmission, power transmission loss is small and the construction cost of power transmission facilities is low, so it is economically advantageous especially for long-distance power transmission. Furthermore, by using HVDC power transmission, connection between systems with different frequencies becomes easy, so it is also suitable for power exchange between regions with different commercial power frequencies. This point is particularly suitable when the commercial power frequencies are different in each region even within the same country, such as in Japan.

[0003] In a DC power transmission system that performs DC power transmission, a converter that mutually converts power from AC to DC or from DC to AC is required. The converter generally operates according to a control signal from a control device. When the output of the control signal from the control device stops due to an abnormality such as an accident or a failure, the converter cannot operate and the DC power transmission system stops. Such an unexpected system stop will have a great impact on the power system, so it must be avoided. Therefore, in a DC power transmission system, the control device usually has a redundant configuration, and a plurality of control devices simultaneously output control signals to the converter. This prevents the entire DC power transmission system from stopping even if an abnormality occurs in one control device.

[0004] After an abnormality occurs in one of the redundantly configured control devices, when restoring the control device and restarting the redundant operation, it is necessary to do this without stopping DC power transmission.

[0005] Regarding the restoration of a DC power transmission system, for example, the technology of Patent Document 1 is known. In the AC-DC conversion system described in Patent Document 1, when a device in one of the duplicated series malfunctions and the faulty device is repaired, the control angle of the control device of the repaired series is compared with the control angle of the control device during normal operation of the other series, and when they match, the lock of the repaired series can be released.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the AC-DC conversion system of Patent Document 1, in order to match the control angle of the control device of the repaired series with the control angle of the control device during normal operation of the other series, it is necessary to manually operate the control device of the repaired series. Therefore, the risk of incorrect operation due to human error cannot be eliminated, which may prevent normal system restoration.

[0008] The present invention has been made in view of the above problems, and the main object is to easily and surely perform the restoration process of the DC power transmission system.

Means for Solving the Problems

[0009] The DC power transmission control device according to the present invention is provided in each of a plurality of control series included in a DC power transmission system, and controls the DC power transmission system according to a control command input from an operation command device. The DC power transmission control device includes an output lock unit that outputs an abnormal signal indicating that an abnormality has occurred in its own control series to the operation command device, a series lock processing unit that receives a series lock signal transmitted from the operation command device in response to the abnormal signal and shifts its own control series to a series lock state, a recovery processing unit that receives an inter-series verification signal transmitted from the operation command device, determines whether or not its own control series has recovered from the abnormality, and outputs a series recovery signal for returning its own control series to the control of the DC power transmission system to the operation command device based on the result of the determination, and a series lock release unit that receives a series lock release signal transmitted from the operation command device in response to the series recovery signal and releases the series lock state. The recovery processing unit includes a deblocking determination unit that determines whether or not its own control series is in the process of deblocking, an inter-series verification unit that performs verification between the control state of its own control series and the control state of other control series using the determination result of the deblocking determination unit, and determines whether or not its own control series satisfies the series recovery condition based on the result of the verification, and a series recovery signal output unit that outputs the series recovery signal when it is determined by the inter-series verification unit that the series recovery condition is satisfied. The inter-series verification unit outputs an inter-series alignment signal for aligning the control state of its own control series and the control state of other control series, and the deblocking determination unit determines whether or not its own control series is in the process of deblocking using the inter-series alignment signal. The DC power transmission control method according to the present invention uses a DC power transmission control device provided in each of a plurality of control series of a DC power transmission system, and performs control of the DC power transmission system according to a control command input from an operation command device. The DC power transmission control device outputs an abnormal signal indicating that an abnormality has occurred in its own control series to the operation command device, receives a series lock signal transmitted from the operation command device according to the abnormal signal, and shifts its own control series to a series lock state. It receives an inter-series verification signal transmitted from the operation command device, determines whether its own control series has recovered from the abnormality, and outputs a series return signal for returning its own control series to the control of the DC power transmission system to the operation command device based on the result of the determination. It receives a series lock release signal transmitted from the operation command device according to the series return signal, releases the series lock state. In the determination, when a predetermined condition is satisfied, an inter-series alignment signal for aligning the control state of its own control series with the control state of other control series is output, a deblocking determination for determining whether its own control series is in the process of deblocking is performed using the inter-series alignment signal, the control state of its own control series is compared with the control state of the other control series using the result of the deblocking determination, and it is determined whether its own control series satisfies the series return condition for outputting the series return signal based on the result of the comparison.

Effects of the Invention

[0010] According to the present invention, the recovery process of the DC power transmission system can be performed easily and surely.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0013] FIG. 1 is a configuration diagram of a DC power transmission system according to an embodiment of the present invention. The DC power transmission system 100 shown in FIG. 1 includes an operation command device 1, a control unit 2, and a power conversion unit 3. The control unit 2 has a first control series 2A including a communication device 10A and a DC power transmission control device 20A, and a second control series 2B including a communication device 10B and a DC power transmission control device 20B.

[0014] The operation command device 1 outputs control commands for the DC power transmission control devices 20A and 20B to the first control series 2A and the second control series 2B, respectively. For example, according to a user's operation, the operation command device 1 can determine the control content to be instructed to the DC power transmission control devices 20A and 20B and output a control command corresponding to the control content.

[0015] The control commands output from the operation command device 1 to the DC power transmission control devices 20A and 20B are input to the communication devices 10A and 10B in the first control series 2A and the second control series 2B, respectively. The communication devices 10A and 10B relay the control commands between the operation command device 1 and the DC power transmission control devices 20A and 20B by outputting the input control commands to the DC power transmission control devices 20A and 20B in their respective control series.

[0016] Based on the control command input from the operation command device 1 via the communication device 10A, the DC power transmission control device 20A generates and outputs a pulse signal for the power conversion unit 3. Similarly, based on the control command input from the operation command device 1 via the communication device 10B, the DC power transmission control device 20B generates and outputs a pulse signal for the power conversion unit 3. Here, between the DC power transmission control device 20A and the DC power transmission control device 20B, it is necessary to make their internal states match and output the same pulse signal to the power conversion unit 3 at the same timing. Therefore, the DC power transmission control device 20A and the DC power transmission control device 20B notify each other of their operation control angles and operation states by transmitting and receiving inter-series signals to and from each other.

[0017] The communication devices 10A and 10B receive the status signals transmitted from the communication devices (not shown) of the destination system of the DC power transmission performed by the DC power transmission system 100, and transmit them to the DC power transmission control devices 20A and 20B of their own control series respectively. The status signal transmitted from the communication device of the destination system is a signal representing the control state of the control device (not shown) of the destination system. Also, the DC power transmission control devices 20A and 20B output status signals corresponding to their own control states to the communication devices 10A and 10B respectively. The communication devices 10A and 10B relay the status signals from the DC power transmission control devices 20A and 20B and transmit them to the communication devices of the destination system respectively. Thereby, status signals corresponding to each other's control states are transmitted and received between the DC power transmission system 100 and the destination system.

[0018] The power conversion unit 3 includes converter control devices 31A, 31B, 31C and converters 32A, 32B, 32C. The converter control devices 31A to 31C generate ignition pulses based on the pulse signals from the DC power transmission control devices 20A, 20B and output them to the converters 32A to 32C respectively. The converters 32A to 32C each have a switching element for the upper arm and a switching element for the lower arm, and alternately turn on and off these switching elements according to the ignition pulses from the converter control devices 31A to 31C, thereby mutually converting DC power and AC power. The switching elements of the converters 32A to 32C are configured using, for example, IGBTs (Insulated Gate Bipolar Transistors).

[0019] As described above, in the DC power transmission system 100, the operation of the power conversion unit 3 is controlled according to the pulse signals output from the DC power transmission control devices 20A, 20B provided in the first control series 2A and the second control series 2B respectively, so that the DC power transmission by the DC power transmission system 100 is controlled.

[0020] Note that in this embodiment, an example in which the power conversion unit 3 includes converters 32A to 32C and converter control devices 31A to 31C, and the power conversion unit 3 mutually converts DC power and AC power by combining these three converters and converter control devices has been described. However, the configuration of the power conversion unit 3 is not limited to this. For example, the power conversion unit 3 may be configured using two or fewer or four or more converters and converter control devices, or the converters and converter control devices may not be associated one-to-one. Also, the control unit 2 may have three or more control series. As long as the control unit 2 has a plurality of redundant control series and mutually converts DC power and AC power by controlling the operation of the power conversion unit 3 using these plurality of control series, the DC power transmission system 100 can be realized using the control unit 2 and the power conversion unit 3 with any configuration.

[0021] Next, the hardware configuration of the DC power transmission control devices 20A and 20B will be described below with reference to FIG. 2. Here, the DC power transmission control device 20A and the DC power transmission control device 20B are respectively used in the redundant first control series 2A and second control series 2B, and have a common hardware configuration and functions. Therefore, hereinafter, both the DC power transmission control device 20A and the DC power transmission control device 20B will be collectively referred to as the "DC power transmission control device 20", and this DC power transmission control device 20 may be described.

[0022] FIG. 2 is a diagram showing an example of the hardware configuration of the DC power transmission control device 20.

[0023] The DC power transmission control device 20 can be realized by using a general information processing device such as a PC (Personal Computer) or a server. As shown in FIG. 2, the DC power transmission control device 20 includes a processor 101, a memory 102, an external storage device 103, a communication interface (communication IF) 104, an input / output device 105, and a communication bus 106 that connects these respective parts.

[0024] The processor 101 controls each part of the DC power transmission control device 20. The processor 101 is configured by using, for example, a CPU (Central Processing Unit), and can realize each function of the DC power transmission control device 20 by executing a program stored in the memory 102. Note that instead of the processor 101, a combination of logic circuits or an FPGA (Field Programmable Gate Array) or the like may be used to realize some or all of the functions of the DC power transmission control device 20.

[0025] The memory 102 is, for example, a semiconductor storage device such as a RAM (Random Access Memory), and temporarily stores a program loaded from the external storage device 103 and executed by the processor 101, as well as necessary work data.

[0026] The external memory device 103 is a large-capacity non-volatile magnetic memory device or semiconductor memory device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores programs executed by the processor 101 and data used for the processing of the processor 101. As described above, some or all of these programs and data may be stored in the external memory device 103 in advance, or may be introduced via a network from a device equipped with an external non-volatile storage medium as needed, or via a portable non-volatile storage medium.

[0027] The communication IF 104 operates according to the control of the processor 101, and performs interface processing for transmitting and receiving various signals and information between the DC power transmission control device 20 and other devices.

[0028] The input / output device 105 is a device that receives inputs from a user who manages the DC power transmission system 100 and outputs information to be presented to the user, and is configured using, for example, a mouse, a keyboard, a display, and the like.

[0029] Subsequently, the series lock function and recovery function of the DC power transmission control device 20 of the present embodiment will be described.

[0030] The series lock function refers to a function that prohibits the operation control of the power conversion unit 3 by a control series in the first control series 2A or the second control series 2B when an abnormality occurs, for example, due to a failure of the communication devices 10A, 10B or the DC power transmission control devices 20A, 20B. When the series lock function is enabled in either control series, the DC power transmission control device 20 (the DC power transmission control device 20A of the first control series 2A or the DC power transmission control device 20B of the second control series 2B) in that control series stops the output of the pulse signal and prohibits the operation control of the power conversion unit 3 by that control series. At this time, the operation control of the power conversion unit 3 is continued using the healthy control series in which the series lock function is not enabled. Note that when the series lock function is enabled, the transmission and reception of inter-series signals between the DC power transmission control devices 20A and 20B are stopped.

[0031] The recovery function refers to a function that releases the series lock state of a control series when the abnormality that occurred in either the first control series 2A or the second control series 2B is resolved and returns to normal, and restores the redundant control system of the DC power transmission system 100 by the first control series 2A and the second control series 2B. After the series lock function is enabled in either control series, by performing a predetermined recovery procedure by the recovery function, the output of the pulse signal from that control series and the transmission and reception of inter-series signals between the DC power transmission control devices 20A and 20B are restarted, and it is possible to return to the operation control of the power conversion unit 3 using both the first control series 2A and the second control series 2B.

[0032] Here, before explaining the details of the series lock function and the recovery function in the DC power transmission control device 20 of the present embodiment, as a comparative example of the present embodiment, the series lock function and the recovery function in a conventional DC power transmission control device will be described below with reference to FIGS. 3 to 5. In the following, the DC power transmission control devices 20A and 20B in the DC power transmission system 100 of FIG. 1 are respectively replaced with the DC power transmission control device 20C according to the comparative example, and the series lock function and the recovery function in this DC power transmission control device 20C will be described.

[0033] FIG. 3 is a functional block diagram regarding the series lock function and the recovery function in the DC power transmission control device 20C according to the comparative example. The DC power transmission control device 20C has functions of an output lock unit 21, a series lock processing unit 22, a recovery processing unit 23C, and a series lock release unit 24. These functions are realized by the processor 101 executing a predetermined program in the DC power transmission control device 20C having a hardware configuration similar to that of FIG. 2, for example.

[0034] When any abnormality such as a device abnormality or a power failure occurs in the self-control series (the first control series 2A or the second control series 2B), the output lock unit 21 detects the abnormality and outputs an abnormality signal indicating that the abnormality has occurred. The abnormality signal output from the output lock unit 21 is transmitted from the DC power transmission control device 20C to the operation command device 1 and input to the recovery processing unit 23C.

[0035] The operation command device 1 has a control signal output unit 14 configured to include each logic circuit of an OR circuit 141, an AND circuit 142, an RS-FF circuit 143, and an AND circuit 144.

[0036] The abnormality signal transmitted from the DC power transmission control device 20C is input to the OR circuit 141 in the control signal output unit 14 in the operation command device 1. When an abnormality signal is input from the operation command device 1 or a series lock command 11 is input according to a user operation on the operation command device 1, the OR circuit 141 changes the output signal to the set terminal of the RS-FF circuit 143 from "0" to "1". When the signal input to the set terminal of the RS-FF circuit 143 changes from "0" to "1", the RS-FF circuit 143 transmits a series lock signal for stopping the operations of the devices in the same control series to the DC power transmission control device 20C.

[0037] The series lock signal transmitted from the operation command device 1 is input to the series lock processing unit 22 in the DC power transmission control device 20C. When the series lock signal is input from the operation command device 1, the series lock processing unit 22 stops the operation of the DC power transmission control device 20C and shifts the self-control series to the series lock state. In the control series in the series lock state, as described above, the output of the pulse signal from the DC power transmission control device 20C to the power conversion unit 3 stops, and the transmission and reception of the inter-series signals mutually performed between the DC power transmission control devices 20C of other control series stop. As a result, among the first control series 2A and the second control series 2B, the control series in which an abnormality has occurred is disconnected from the DC power transmission system 100, and the operation of the power conversion unit 3 is controlled using only the normal control series.

[0038] After removing the cause of the abnormality in the control series in the series lock state and starting the recovery operation, when the user operates the operation command device 1 to input an inter-series verification command 12 for verifying the control state between the control series. The inter-series verification command 12 is input to the AND circuit 144 in the control signal output unit 14 in the operation command device 1. When the inter-series verification command 12 is input to the AND circuit 144 during the transmission of the series lock signal from the RS-FF circuit 143, the AND circuit 144 transmits an inter-series verification signal to the DC power transmission control device 20C.

[0039] The inter-series verification signal transmitted from the operation command device 1 is input to the recovery processing unit 23C in the DC power transmission control device 20C. The recovery processing unit 23C includes a deblock determination unit 231C, an inter-series verification unit 232C, and an inter-series return signal output unit 233.

[0040] When the inter-series verification signal is input from the operation command device 1, the de-block determination unit 231C checks whether the BPP completion condition is satisfied in the self-control series accordingly, and determines whether the self-control series is in the de-block state based on the check result. The BPP completion condition is a condition for checking whether the control state of the self-control series corresponds to the BPP state (bypass pair state) in which the upper and lower arms of the converters 32A to 32C in the power conversion unit 3 are simultaneously on. Details of the de-block determination method by the de-block determination unit 231C will be described later.

[0041] Using the determination result of the de-block determination unit 231C, the inter-series verification unit 232C verifies the control state of the self-control series and the control state of other control series, and determines whether the self-control series satisfies the series return condition based on the verification result. The series return condition is a condition for checking whether it is possible to release the series lock state of the self-control series, permit return to the redundant control system, and resume the operation control of the power conversion unit 3 by the DC power transmission control device 20C of the self-control series, thereby returning the self-control series to the control of the DC power transmission system 100. Details of the method for verifying the control states between series by the inter-series verification unit 232C will be described later.

[0042] When it is determined by the inter-series verification unit 232C that the self-control series satisfies the series return condition, the series return signal output unit 233 outputs a series return signal for returning the self-control series to the redundant control system. The series return signal output from the series return signal output unit 233 is transmitted from the DC power transmission control device 20C to the operation command device 1, and is input to the AND circuit 142 in the control signal output unit 14 in the operation command device 1.

[0043] When releasing the series lock state of the self-control series, the user operates the operation command device 1 to input a series lock release command 13. The series lock release command 13 is input into the AND circuit 142 in the control signal output unit 14 in the operation command device 1. When the series lock release command 13 is input during the transmission of the series return signal from the DC power transmission control device 20C, the AND circuit 142 changes the output signal to the reset terminal of the RS-FF circuit 143 from "0" to "1". When the signal input to the reset terminal of the RS-FF circuit 143 changes from "0" to "1", the RS-FF circuit 143 transmits a series lock release signal for releasing the series lock state to the DC power transmission control device 20C.

[0044] The series lock release signal transmitted from the operation command device 1 is input into the series lock release unit 24 in the DC power transmission control device 20C. When the series lock release signal is input from the operation command device 1, the series lock release unit 24 releases the series lock state of the self-control series and resumes the operation of the DC power transmission control device 20C. In the control series with the series lock state released, similar to the case of the DC power transmission control device 20 described above, the output of the pulse signal from the DC power transmission control device 20C to the power conversion unit 3 and the transmission and reception of the inter-series signals mutually performed with the DC power transmission control devices 20C of other control series are resumed. Thereby, it is possible to return to the operation of the DC power transmission system 100 using the redundant control system by both the first control series 2A and the second control series 2B.

[0045] FIG. 4 is a diagram showing the details of the deblock determination unit 231C according to the comparative example. The deblock determination unit 231C shown in FIG. 4 determines whether the self-control series is in the deblock state based on the determination conditions 41 to 45.

[0046] The determination condition 41 is based on the condition that the converters 32A to 32C satisfy the BPP completion condition for the self-control series. The confirmation of the determination condition 41 is performed, for example, based on the presence or absence of the BPP completion signal output from the converters 32A to 32C to the DC power transmission control device 20C at the first startup.

[0047] Determination condition 42 is such that, instead of determination condition 41, it is conditional on satisfying the BPP completion condition depending on the presence or absence of a user's forced instruction. The confirmation of determination condition 42 is performed, for example, based on whether or not the user has performed a predetermined operation input on the DC power transmission control device 20C.

[0048] Determination condition 43 is conditional on the converters 32A to 32C being in the stopped BPP state. The confirmation of determination condition 43 is performed, for example, based on the presence or absence of an output of a stop command signal from the DC power transmission control device 20C to the converters 32A to 32C.

[0049] Determination condition 44 is conditional on the converters 32A to 32C satisfying the BPP completion condition for another control sequence. The confirmation of determination condition 44 is performed in the same manner as determination condition 41, for example, based on the presence or absence of a BPP completion signal output from the converters 32A to 32C to the DC power transmission control device 20C at the time of first startup.

[0050] Determination condition 45 is such that, instead of determination condition 44, it is conditional on satisfying the BPP completion condition depending on the presence or absence of a user's forced instruction. The confirmation of determination condition 45 is performed in the same manner as determination condition 42, for example, based on whether or not the user has performed a predetermined operation input on the DC power transmission control device 20C.

[0051] In the deblock determination unit 231C, when at least one of determination conditions 41 and 42 is satisfied, the output signal of the OR circuit 51 becomes "1". Also, when at least one of determination conditions 44 and 45 is satisfied, the output signal of the OR circuit 52 becomes "1". When the output signal of the OR circuit 51 is "1" or determination condition 43 is satisfied, the output signal of the OR circuit 53 becomes "1".

[0052] When the output signal of the OR circuit 53 is “1”, it is determined that the local-end BPP completion condition is satisfied. When the output signal of the OR circuit 52 is “1”, it is determined that the other-end BPP completion condition is satisfied. When the local-end BPP completion condition is satisfied and the other-end BPP completion condition is satisfied, the output signal of the AND circuit 54 becomes “1”, and a determination result of “in the process of deblocking” is obtained as the determination result 60 of the deblocking determination unit 231C.

[0053] In the deblocking determination unit 231C of FIG. 4, when the determination conditions 42 and 45 are not considered, in order for the determination result 60 to be “in the process of deblocking”, it is necessary to satisfy either of the determination conditions 41 and 43 and the determination condition 44. However, in order to satisfy these determination conditions, the converters 32A to 32C need to be before the start of operation after the first startup or in a stopped state. Therefore, in a state where the operation control of the power conversion unit 3 is being performed using a sound control sequence without the occurrence of an abnormality as described above, these determination conditions are not satisfied. Therefore, when restoring the control sequence in which an abnormality has occurred and returning to the control of the DC power transmission system 100, the determination result 60 cannot be set to “in the process of deblocking”. Therefore, in the DC power transmission control device 20C of the comparative example, the determination conditions 42 and 45 by the user's forced instruction are used to forcibly set the determination result 60 to “in the process of deblocking”.

[0054] FIG. 5 is a diagram showing details of the inter-sequence collation unit 232C according to the comparative example. The inter-sequence collation unit 232C shown in FIG. 5 collates the control state of the self-control sequence and the control state of the other control sequence based on the determination conditions 61 to 68, and determines whether the sequence return condition is satisfied in the self-control sequence.

[0055] The determination condition 61 is conditional on the self-control sequence being in the process of deblocking. The confirmation of the determination condition 61 is performed using the determination result 60 obtained by the deblocking determination unit 231C.

[0056] The determination condition 62 is conditional on the fact that another control sequence is in the process of unlocking. The confirmation of the determination condition 62 is performed, for example, based on an inter-sequence signal transmitted from the DC power transmission control device 20C of another control sequence.

[0057] The determination condition 63 is conditional on the fact that the power flow direction of the self-control sequence is on the power transmission side and the power conversion unit 3 is controlled by the self-control sequence to perform power conversion from AC power to DC power. The confirmation of the determination condition 63 is performed, for example, based on the control state of the DC power transmission control device 20C of the self-control sequence.

[0058] The determination condition 64 is conditional on the fact that the power flow direction of another control sequence is on the power transmission side and the power conversion unit 3 is controlled by another control sequence to perform power conversion from AC power to DC power. The confirmation of the determination condition 64 is performed, for example, based on an inter-sequence signal transmitted from the DC power transmission control device 20C of another control sequence.

[0059] The determination condition 65 is conditional on the fact that the control values of the self-control sequence and another control sequence match. The confirmation of the determination condition 65 is performed, for example, based on the control state of the DC power transmission control device 20C of the self-control sequence and an inter-sequence signal transmitted from the DC power transmission control device 20C of another control sequence.

[0060] The determination condition 66 is conditional on the fact that an abnormality has occurred in the self-control sequence and the signal output from the DC power transmission control device 20C has stopped. The confirmation of the determination condition 66 is performed, for example, based on the operation state of the output lock unit 21.

[0061] The determination condition 67 is conditional on the fact that a lock command has been issued for the self-control sequence. The confirmation of the determination condition 67 is performed, for example, based on a sequence lock signal output from the operation command device 1 to the self-control sequence.

[0062] The determination condition 68 is based on the condition that an inter-series collation command is being issued for the self-control series. The confirmation of the determination condition 68 is performed, for example, based on an inter-series collation signal output from the operation command device 1 to the self-control series.

[0063] In the inter-series collation unit 232C, when the determination results of the determination conditions 61 and 62 match, the output signal of the XOR circuit 71 becomes "0", and when they do not match, that is, when only one of the determination conditions is satisfied, the output signal of the XOR circuit 71 becomes "1". Also, when the determination results of the determination conditions 63 and 64 match, the output signal of the XOR circuit 72 becomes "0", and when they do not match, that is, when only one of the determination conditions is satisfied, the output signal of the XOR circuit 72 becomes "1". When the output signals of both the XOR circuits 71 and 72 are "0", the output signal of the OR circuit 73 becomes "0", and when at least one of the output signals is "1", the output signal of the OR circuit 73 becomes "1".

[0064] The NOT circuit 74 inverts and outputs the output signal of the OR circuit 73. As a result, when the determination results of the determination conditions 61 and 62 match and the determination results of the determination conditions 63 and 64 match, the output signal of the NOT circuit 74 becomes "1", and in other cases, the output signal of the NOT circuit 74 becomes "0".

[0065] When the output signal of the NOT circuit 74 is "1" and the determination conditions 65 and 68 are each satisfied, the output signal of the AND circuit 75 becomes "1". Also, when the determination condition 66 is not satisfied and the determination conditions 67 and 68 are each satisfied, the output signal of the AND circuit 76 becomes "1". The output signals of the AND circuits 75 and 76 are each delayed by a predetermined timer time by the timers 77 and 78 and input to the AND circuit 79. When the output signals of both the AND circuits 75 and 76 are "1", the output signal of the AND circuit 79 becomes "1", and a determination result of "series return condition established" is obtained as the determination result 80 of the inter-series collation unit 232C. As a result, a series return signal is output from the series return signal output unit 233 and transmitted to the operation command device 1.

[0066] Note that, as described above, in the unlocking determination unit 231C, in an operating state with a sound control sequence without any abnormality, the determination result of "during unlocking" cannot be obtained unless a forced instruction from the user is given. Therefore, the sequence comparison unit 232C cannot satisfy the determination condition 61 and cannot obtain the determination result of "sequence return condition established". As described above, in the DC power transmission control device 20C according to the comparative example, if the DC power transmission control device 20C of the control sequence in which an abnormality has occurred is once stopped and disconnected from the system, the redundant control system cannot be restored without a forced instruction from the user even after the abnormality has been removed. Therefore, it was necessary for the user to forcibly adjust between the control sequences.

[0067] Therefore, in the DC power transmission control device 20 of the present embodiment, in the sequence lock function and the restoration function, the redundant control system can be automatically restored without a forced instruction from the user. Hereinafter, with reference to FIGS. 6 to 8, the sequence lock function and the restoration function in the DC power transmission control device 20 of the present embodiment will be described. In FIGS. 6 to 8, the same parts as those in FIGS. 3 to 5 described in the comparative example are denoted by common reference numerals. Hereinafter, the description of the parts denoted by the same reference numerals as those in FIGS. 3 to 5 will be omitted unless particularly necessary.

[0068] FIG. 6 is a functional block diagram relating to the sequence lock function and the restoration function in the DC power transmission control device 20 according to an embodiment of the present invention. The DC power transmission control device 20 of the present embodiment is the same as the DC power transmission control device 20C of the comparative example described in FIG. 3, except that it has a restoration processing unit 23 instead of the restoration processing unit 23C. Each function shown in FIG. 3 is realized, for example, when the processor 101 executes a predetermined program.

[0069] The restoration processing unit 23 includes a deblock determination unit 231, an inter-sequence collation unit 232, and an inter-sequence return signal output unit 233. These have the same functions as the deblock determination unit 231C, the inter-sequence collation unit 232C, and the inter-sequence return signal output unit 233C in the restoration processing unit 23C of FIG. 3, respectively. However, the deblock determination method by the deblock determination unit 231 and the collation method of the control states between sequences by the inter-sequence collation unit 232 are different from those of the comparative example, respectively.

[0070] FIG. 7 is a diagram showing details of the deblock determination unit 231 according to an embodiment of the present invention. In the deblock determination unit 231 shown in FIG. 7, in addition to the determination conditions 41, 43, and 44 described with reference to FIG. 4, an inter-sequence alignment signal 85 output from the inter-sequence collation unit 232 is further provided as a determination condition. The deblock determination unit 231 determines whether the self-control sequence is in the deblock state based on these determination conditions. The output conditions of the inter-sequence alignment signal 85 in the inter-sequence collation unit 232 will be described later. On the other hand, different from the deblock determination unit 321C of the comparative example shown in FIG. 4, the determination conditions 42 and 45 by the user's forced instruction are not included in the deblock determination unit 231.

[0071] In the deblock determination unit 231, when at least one of the determination conditions 41 and 43 is satisfied, the output signal of the OR circuit 53 becomes "1". When the output signal of the OR circuit 53 is "1" or the inter-sequence alignment signal 85 is input, the output signal of the OR circuit 55 becomes "1". Also, when the determination condition 44 is satisfied or the inter-sequence alignment signal 85 is input, the output signal of the OR circuit 56 becomes "1".

[0072] When the output signal of the OR circuit 55 is "1", it is determined that the self-end BPP completion condition is satisfied. When the output signal of the OR circuit 56 is "1", it is determined that the other-end BPP completion condition is satisfied. When the self-end BPP completion condition is satisfied and the other-end BPP completion condition is satisfied, the output signal of the AND circuit 54 becomes "1", and a determination result of "in the deblock state" is obtained as the determination result 60 of the deblock determination unit 231.

[0073] In the DC power transmission control device 20 of this embodiment, instead of the determination conditions 42 and 45 based on the user's forced instruction, the inter-series alignment signal 85 output from the inter-series collation unit 232 is used as the determination condition. As a result, even if the user does not forcibly perform the alignment between control series, if the inter-series alignment signal 85 is output from the inter-series collation unit 232, the determination result 60 in the deblock determination unit 231 is set to "in the process of deblocking".

[0074] FIG. 8 is a diagram showing details of the inter-series collation unit 232 according to an embodiment of the present invention. The inter-series collation unit 232 shown in FIG. 8 further includes a NOT circuit 81, a timer 82, a one-shot circuit 83, and an AND circuit 84 in addition to the configuration described with reference to FIG. 5 in order to output the inter-series alignment signal 85.

[0075] In the inter-series collation unit 232, the determination result of the determination condition 61 is inverted by the NOT circuit 81 and input to the AND circuit 84. Also, the output signal of the AND circuit 76 is delayed by a predetermined timer time by the timer 82 and input to the one-shot circuit 83. When the output signal of the AND circuit 76 becomes "1", the one-shot circuit 83 outputs a predetermined pulse signal to the AND circuit 84 only once.

[0076] When the pulse signal is output from the one-shot circuit 83 and the determination condition 61 is not satisfied and the determination condition 62 is satisfied, the output signal of the AND circuit 84 becomes "1". As a result, the inter-series alignment signal 85 is output from the inter-series return signal output unit 233 and input to the deblock determination unit 231. Using this inter-series alignment signal 85, the determination result 60 of the deblock determination unit 231 can be set to "in the process of deblocking". Therefore, even if the user does not forcibly perform the alignment between control series, it is possible to automatically recover the redundant control system.

[0077] According to the embodiment of the present invention described above, the following operational effects can be obtained.

[0078] (1) The DC power transmission control device 20 is provided in the first control series 2A and the second control series 2B of the DC power transmission system 100, and controls the DC power transmission system 100 according to a control command input from the operation command device 1. The DC power transmission control device 20 includes an output lock unit 21 that outputs an abnormal signal indicating that an abnormality has occurred in its own control series to the operation command device 1, a series lock processing unit 22 that receives a series lock signal transmitted from the operation command device 1 in response to the abnormal signal, and shifts its own control series to a series lock state, and a recovery processing unit 23 that receives an inter-series verification signal transmitted from the operation command device 1, determines whether or not its own control series has recovered from the abnormality, and outputs a series recovery signal for returning its own control series to the control of the DC power transmission system 100 to the operation command device 1 based on the result of the determination, and a series lock release unit 24 that receives a series lock release signal transmitted from the operation command device 1 in response to the series recovery signal and releases the series lock state. The recovery processing unit 23 includes a deblocking determination unit 231 that determines whether or not its own control series is in the process of deblocking, an inter-series verification unit 232 that uses the determination result of the deblocking determination unit 231 to perform verification between the control state of its own control series and the control state of the other control series, and determines whether or not its own control series satisfies the series recovery condition based on the result of the verification, and a series recovery signal output unit 233 that outputs a series recovery signal when it is determined by the inter-series verification unit 232 that the series recovery condition is satisfied. The inter-series verification unit 232 outputs an inter-series alignment signal 85 for aligning the control state of its own control series and the control state of the other control series, and the deblocking determination unit 231 determines whether or not its own control series is in the process of deblocking using the inter-series alignment signal 85. In this way, the recovery process of the DC power transmission system 100 can be performed easily and surely.

[0079] (2) The inter-series matching unit 232 outputs the inter-series alignment signal 85 when the following three conditions are met: the first condition that in the self-control series, the operation of the DC power transmission control device 20 is normal and the series lock signal and the inter-series matching signal are input from the operation command device 1 (judgment condition 66: NG, judgment conditions 67 and 68: OK); the second condition that the self-control series is not in the unlocking state (judgment condition 61: NG); and the third condition that the other control series is in the unlocking state (judgment condition 62: OK). By doing so, when performing inter-series matching in a situation where the control states of the self-control series and the other control series do not match, the inter-series alignment signal 85 can be surely output.

[0080] (3) The inter-series matching unit 232 has a one-shot circuit 83 that outputs a predetermined pulse signal once when the first condition is satisfied, and outputs the inter-series alignment signal 85 using the pulse signal output from the one-shot circuit 83. By doing so, the inter-series alignment signal 85 can be output only from the inter-series matching unit 232 at the necessary timing, and the occurrence of misjudgment in the unlocking determination unit 231 can be avoided.

[0081] (4) The unlocking determination unit 231 determines that the self-control series is in the unlocking state when a BPP completion signal indicating that the converters 32A to 32C that mutually convert DC power and AC power are in the BPP state is input (judgment conditions 41 and 44: OK), or when the inter-series alignment signal 85 is output from the inter-series matching unit 232 (judgment result 60: "unlocking"). By doing so, in the DC power transmission system 100, during the continuous operation of a healthy control series, even if the user does not forcibly perform alignment between control series, a determination result that the self-control series is in the unlocking state can be obtained. As a result, it becomes possible to return the self-control series to the control of the DC power transmission system 100 and to restore the redundant control system.

[0082] Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist thereof. For example, the above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the described configurations. Also, for a part of the configuration of the above embodiments, addition, deletion, or replacement with other configurations is possible.

[0083] Also, each of the above configurations, functional units, processing units, processing means, etc. may be realized in hardware by designing a part or all of them, for example, by an integrated circuit. Also, each of the above configurations, functions, etc. may be realized in software by a processor interpreting and executing a program for realizing each function. Information such as programs, tables, files, etc. for realizing each function can be placed in a recording device such as a memory, hard disk, SSD, or a recording medium such as an IC card, SD card, DVD.

Explanation of Reference Numerals

[0084] 1: Operation command device, 2: Control unit, 2A: First control series, 2B: Second control series, 3: Power conversion unit, 10A, 10B: Communication device, 20, 20A, 20B: DC power transmission control device, 21: Output lock unit, 22: Series lock processing unit, 23: Recovery processing unit, 24: Series lock release unit, 31A, 31B, 31C: Converter control device, 32A, 32B, 32C: Converter, 100: DC power transmission system, 231: Deblock determination unit, 232: Inter-series collation unit, 233: Series return signal output unit

Claims

1. A DC power transmission control device provided in each of a plurality of control sequences of a DC power transmission system, and configured to control the DC power transmission system according to a control command input from an operation command device, comprising: an output lock unit that outputs an abnormal signal indicating that an abnormality has occurred in the self-control sequence to the operation command device; a sequence lock processing unit that receives a sequence lock signal transmitted from the operation command device in response to the abnormal signal, and shifts the self-control sequence to a sequence lock state; a recovery processing unit that receives an inter-sequence verification signal transmitted from the operation command device, determines whether the self-control sequence has recovered from the abnormality, and outputs a sequence recovery signal to the operation command device for returning the self-control sequence to the control of the DC power transmission system based on the result of the determination; a sequence lock release unit that receives a sequence lock release signal transmitted from the operation command device in response to the sequence recovery signal, and releases the sequence lock state, wherein the recovery processing unit comprises a deblocking determination unit that determines whether the self-control sequence is in the process of deblocking; an inter-sequence verification unit that performs verification between the control state of the self-control sequence and the control states of other control sequences using the determination result of the deblocking determination unit, and determines whether the self-control sequence satisfies the sequence recovery condition based on the result of the verification; and a sequence recovery signal output unit that outputs the sequence recovery signal when it is determined by the inter-sequence verification unit that the sequence recovery condition is satisfied; wherein the inter-sequence verification unit outputs an inter-sequence alignment signal for aligning the control state of the self-control sequence and the control states of other control sequences; and the deblocking determination unit determines whether the self-control sequence is in the process of deblocking using the inter-sequence alignment signal. A DC power transmission control device.

2. The DC power transmission control device according to Claim 1, wherein the inter-sequence verification unit satisfies a first condition that the operation of the DC power transmission control device in the self-control sequence is normal and the sequence lock signal and the inter-sequence verification signal are input from the operation command device; a second condition that the self-control sequence is not in the process of deblocking; and a third condition that the other control sequences are in the process of deblocking, and outputs the inter-sequence alignment signal when these conditions are satisfied. A DC power transmission control device.

3. The DC power transmission control device according to Claim 2, The inter-series matching unit has a one-shot circuit that outputs a predetermined pulse signal once when the first condition is satisfied, and outputs the inter-series alignment signal using the pulse signal output from the one-shot circuit. A DC power transmission control device.

4. A DC power transmission control device according to any one of claims 1 to 3, wherein the deblocking determination unit determines that the self-control series is in a deblocking state when a BPP completion signal indicating that a converter that mutually converts DC power and AC power is in a BPP state is input, or when the inter-series alignment signal is output from the inter-series matching unit. A DC power transmission control device.

5. A DC power transmission control method using a DC power transmission control device provided in each of a plurality of control series included in a DC power transmission system, and controlling the DC power transmission system according to a control command input from an operation command device, by the DC power transmission control device, output an abnormal signal indicating that an abnormality has occurred in the self-control series to the operation command device, receive a series lock signal transmitted from the operation command device in response to the abnormal signal, and shift the self-control series to a series locked state, receive an inter-series matching signal transmitted from the operation command device, and determine whether the self-control series has recovered from the abnormality, output a series return signal for returning the self-control series to the control of the DC power transmission system to the operation command device based on the result of the determination, receive a series lock release signal transmitted from the operation command device in response to the series return signal, and release the series locked state, in the determination, when a predetermined condition is satisfied, output an inter-series alignment signal for aligning the control state of the self-control series and the control state of other control series, perform a deblocking determination to determine whether the self-control series is in a deblocking state using the inter-series alignment signal, perform collation between the control state of the self-control series and the control state of the other control series using the result of the deblocking determination, determine whether the self-control series satisfies a series return condition for outputting the series return signal based on the result of the collation. A DC power transmission control method.

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