Protection control monitoring system and protection control monitoring device

Abstract

This protection control monitoring system is provided with: a first protection control monitoring device having a measurement unit for measuring a reception timing of data and an adjustment unit for regulating a transmission timing for transmitting data; and, a second protection control monitoring device having a measurement unit for measuring a reception timing of data and a correction unit for correcting a sampling timing of data. The adjustment unit of the first protection control monitoring device regulates the transmission timing on the basis of the time difference between: the reception timing of data transmitted from the second protection control monitoring device, as measured by the measurement unit of the first protection control monitoring device; and, a reception timing, by the second protection control monitoring device, of data transmitted from the first protection control monitoring device, as estimated by the first protection control monitoring device. The correction unit of the second protection control monitoring device corrects the sampling timing after the adjustment unit of the first protection control monitoring device regulates the transmission timing.

Description

[Technical field]

[0001] An embodiment of the present invention relates to a protection control monitoring system and a protection control monitoring device. [Background technology]

[0002] Conventionally, a transmission line differential relay is known that performs differential calculations using terminals installed at both ends of a transmission line to protect the transmission line. In order to perform differential calculations, it is important to synchronize sampling between the terminals to obtain the amount of current in the transmission line. In a normal transmission line differential relay, one terminal notifies the other terminal of the timing of receiving data through a transmission line, and the other terminal performs synchronization control based on the notified reception timing and data of the timing of receiving data at the terminal. However, for example, when a pilot wire is used as a transmission line of a transmission line, there are cases where the data transmission capacity of the transmission line is limited, and the data reception timing cannot be properly notified to the other terminal. As a result, there are cases where it is difficult to achieve sampling synchronization in a transmission line with a limited data transmission capacity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-187994 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a protection control monitoring system and a protection control monitoring device that are capable of achieving sampling synchronization even in a transmission path with a limited data transmission capacity. [Means for solving the problem]

[0005] A protection control monitoring system according to an embodiment includes a first protection control monitoring device having a measurement unit that measures the reception timing of data transmitted from a communication destination and an adjustment unit that adjusts the transmission timing of transmitting data to the communication destination, and a second protection control monitoring device having a measurement unit that measures the reception timing of data transmitted from the communication destination and a correction unit that corrects the sampling timing of data. The adjustment unit of the first protection control monitoring device adjusts the transmission timing based on a time difference between the reception timing of data transmitted from the second protection control monitoring device measured by the measurement unit of the first protection control monitoring device and the reception timing by the second protection control monitoring device of the data transmitted from the first protection control monitoring device assumed by the first protection control monitoring device. The correction unit of the second protection control monitoring device corrects the sampling timing after the adjustment unit of the first protection control monitoring device adjusts the transmission timing, thereby achieving sampling synchronization between the first protection control monitoring device and the second protection control monitoring device. [Brief description of the drawings]

[0006] [Figure 1] 1 is a configuration diagram of a protection control monitoring system 1 according to a first embodiment. [Diagram 2] FIG. 13 is a diagram showing an example of the flow of operations of the transmission timing control means 58A and the sampling synchronization means 56B when the assumed transmission delay time Tdly_exp is longer than the actual transmission delay time Tdly. [Diagram 3] FIG. 13 is a diagram showing an example of the flow of operations of the transmission timing control means 58A and the sampling synchronization means 56B when the assumed transmission delay time Tdly_exp is shorter than the actual transmission delay time Tdly. [Figure 4] 4 is a timing chart showing an example of the flow of processes executed by the first protection and control monitoring device 100A and the second protection and control monitoring device 100B in the first embodiment. [Diagram 5] 10 is a timing chart showing an example of the flow of processes executed by the first protection and control monitoring device 100A and the second protection and control monitoring device 100B in the second embodiment. [Figure 6] FIG. 11 is a configuration diagram of a protection control monitoring system 2 according to a third embodiment. [Figure 7] FIG. 13 is a diagram showing an example of the flow of operations of the transmission timing control means 58A and the sampling synchronization means 56B when an upstream transmission delay time Td_up is longer than a downstream transmission delay time Td_down. [Figure 8] 13 is a diagram showing an example of the flow of operations of the transmission timing control means 58A and the sampling synchronization means 56B when an upstream transmission delay time Td_up is shorter than a downstream transmission delay time Td_down. FIG. [Figure 9] 10 is a diagram for explaining a method of achieving sampling synchronization by correcting reception timing information notified by a first protection and control monitoring device 100A to a second protection and control monitoring device 100B. FIG. [Figure 10] FIG. 23 is a configuration diagram of a protection control monitoring system 3 according to an eighth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, a protection control monitoring system and a protection control monitoring device according to an embodiment will be described with reference to the drawings.

[0008] (First embodiment) 1 is a configuration diagram of a protection control monitoring system 1 according to the first embodiment. The protection control monitoring system 1 includes a first protection control monitoring device 100A connected to one end of a power transmission line L, and a second protection control monitoring device 100B connected to the other end of the power transmission line L (in the following description, when the first protection control monitoring device 100A and the second protection control monitoring device 100B are not distinguished from each other, they may be simply referred to as "protection control monitoring device 100"). The first protection control monitoring device 100A includes an instrument current transformer 10A, an A / D conversion unit 20A, an arithmetic processing unit 30A, a transmission processing unit 40A, a measurement means 52A, a synchronization error detection means 54A, a sampling synchronization means 56A, and a transmission timing control means 58A. The second protection control monitoring device 100B has an instrument current transformer 10B, an A / D conversion unit 20B, an arithmetic processing unit 30B, a transmission processing unit 40B, a measurement means 52B, a synchronization error detection means 54B, a sampling synchronization means 56B, and a transmission timing control means 58B. A configuration including the measurement means 52A, the synchronization error detection means 54A, the sampling synchronization means 56A, and the transmission timing control means 58A corresponds to the sampling synchronization control unit 50A, and a configuration including the measurement means 52B, the synchronization error detection means 54B, the sampling synchronization means 56B, and the transmission timing control means 58B corresponds to the sampling synchronization control unit 50B. In the following description, when there is no distinction between the components of the first protection control monitoring device 100A and the components of the second protection control monitoring device 100B, the reference characters A and B are omitted.

[0009] The instrument current transformer 10 converts a large current flowing through the power transmission line L into a small current and transfers the measured analog current value to the A / D conversion unit 20. The A / D conversion unit 20 samples the analog current value acquired from the instrument current transformer 10 and converts it into digital data. The calculation processing unit 30 executes a protection calculation based on the digital data acquired from the A / D conversion unit 20, and transfers the digital data to the other protection control monitoring device 100 via the transmission processing unit 40. If the calculation processing unit 30 detects an abnormality in the power transmission line L as a result of executing the protection calculation, it transmits a cutoff signal to a circuit breaker (not shown) connected to the power transmission line L, thereby cutting off the current flowing through the power transmission line L.

[0010] The sampling synchronization control unit 50 measures the arrival timing of the data transmitted from the other protection control monitoring device 100, performs predetermined processing, and achieves sampling synchronization by transferring a sampling signal SS indicating the sampling timing to the A / D conversion unit 20A, or transferring a transmission timing signal TS indicating the data transmission timing to the transmission processing unit 40.

[0011] More specifically, the measuring means 52 measures the difference Td_rx between the timing based on the sampling signal SS of the protection control monitoring device 100, which is the own terminal, and the timing when data arrives from the other protection control monitoring device 100. Here, the timing difference Td_rx is expressed by the sum of a transmission waiting period TXst from when the protection control monitoring device 100, which is the own terminal, executes sampling to when it transmits the acquired sampling data to the other protection control monitoring device 100, and a period Tdly (transmission delay time) from when the protection control monitoring device 100, which is the own terminal, transmits the acquired sampling data to the other protection control monitoring device 100 to when the sampling data arrives from the other protection control monitoring device 100. That is, Td_rx=TXst+Tdly is established.

[0012] The synchronization error detection means 54 calculates the difference Tdif (Td_rx-Td_rx0) between the timing difference Td_rx measured by the measurement means 52 and the timing difference Td_rx0 in the transmission path that is assumed in advance by the protection control monitoring device 100, which is the terminal itself, and detects it as the synchronization error Tdif. Here, the timing difference Td_rx0 assumed in advance is expressed as the sum of the transmission waiting period TXst and the assumed period Tdly_exp (assumed transmission delay time) from when the protection control monitoring device 100, which is the terminal itself, transmits the data acquired by the protection control monitoring device 100 to the other protection control monitoring device 100 until the data arrives from the other protection control monitoring device 100. That is, Td_rx0=TXst+Tdly_exp is established, and Tdif=Tdly_exp-Tdly is obtained. In the first embodiment, it is assumed that the transmission delay time Tdly and the expected transmission delay time Tdly_exp between the first protection control monitoring device 100A and the second protection control monitoring device 100B are the same value between the upstream and downstream. This assumption applies, for example, when the first protection control monitoring device 100A and the second protection control monitoring device 100B are directly connected without going through a relay device.

[0013] The sampling synchronization means 56 outputs a sampling signal SS to the A / D conversion unit 20, which indicates a sampling timing SP that eliminates the synchronization error Tdif detected by the synchronization error detection means 54. More specifically, when the synchronization error Tdif=Tdly_exp-Tdly is positive, that is, when the actual transmission delay time Tdly is shorter than the assumed transmission delay time Tdly_exp, the sampling synchronization means 56 outputs a sampling signal SS to indicate a sampling timing SP that delays the sampling timing SP by a period corresponding to the synchronization error Tdif, whereas when the synchronization error Tdif=Tdly_exp-Tdly is negative, that is, when the actual transmission delay time Tdly is longer than the assumed transmission delay time Tdly_exp, the sampling synchronization means 56 outputs a sampling signal SS to indicate a sampling timing SP that advances the sampling timing SP by a period corresponding to the synchronization error Tdif. Note that when the sampling synchronization means 56A and the sampling synchronization means 56B operate simultaneously, the sampling operations may become unstable due to the sampling timing SP simultaneously varying in accordance with each other's sampling signals SS. Therefore, in this embodiment, only the sampling synchronization means 56B of the second protection and control monitoring device 100B operates, and the sampling timing SP of the first protection and control monitoring device 100A is fixed.

[0014] The transmission timing control means 58 sets a transmission standby period TXst from when the A / D conversion unit 20 executes sampling until when the acquired sampling data is transmitted from the transmission processing unit 40 to the other protection control monitoring device 100. Usually, the transmission standby period TXst is set to a common value between the first protection control monitoring device 100A and the second protection control monitoring device 100B, but as described later, in the first embodiment, the transmission timing control means 58A corrects the transmission standby period TXst based on the time difference between the reception timing of the sampling data transmitted from the second protection control monitoring device 100B measured by the measurement means 52A and the reception timing of the data transmitted from the first protection control monitoring device 100A by the second protection control monitoring device 100B, which is assumed by the first protection control monitoring device 100A. The specific operation of the transmission timing control means 58 will be described with reference to FIG. 2 and FIG. 3.

[0015] FIG. 2 is a diagram showing an example of the flow of the operation of the transmission timing control means 58A and the operation of the sampling synchronization means 56B when the assumed transmission delay time Tdly_exp is longer than the actual transmission delay time Tdly. FIG. 2(a) shows a situation in which the sampling synchronization means 56B, which is a slave, attempts to synchronize the sampling timing SPs of the second protection control monitoring device 100B with the sampling timing SPm of the first protection control monitoring device 100A, which is a master, but the assumed transmission delay time Tdly_exp is longer than the actual transmission delay time Tdly by α, causing the sampling timing SPs to deviate forward by α from the sampling timing SPm. That is, from the viewpoint of the second protection control monitoring device 100B, it is assumed that the sampling data transmitted from the second protection control monitoring device 100B has arrived at the first protection control monitoring device 100A at time t2 in FIG. 2(a), and at the same time, the sampling data transmitted from the first protection control monitoring device 100A is received. Therefore, the second protection control monitoring device 100B erroneously recognizes that Tdly_exp=Tdly holds, and the sampling synchronization means 56B sets the sampling timing SPs to a position that is shifted α ahead of the sampling timing SPm.

[0016] On the other hand, the measurement means 52A measures that the sampling data transmitted from the second protection control monitoring device 100B is received at time t1 in FIG. 2(a). At this time, the first protection control monitoring device 100A assumes that the sampling data transmitted to the second protection control monitoring device 100B arrives at the second protection control monitoring device 100B at time t3 in FIG. 2(a). As a result, the synchronization error detection means 54A recognizes that a deviation occurs in the reception timing for a time equivalent to time t3-time t1 (=2α), and detects the synchronization error Tdif=Tdly_exp-Tdly=α. This is because, as described above, in the first embodiment, a transmission path in which the upstream transmission delay time and the downstream transmission delay time are the same is assumed, and therefore the synchronization error detection means 54A can identify α, which is half the time of 2α, as the synchronization error.

[0017] When the synchronization error detection means 54A detects the synchronization error α, the transmission timing control means 58A resets the transmission standby period TXst to the transmission standby period TXst+α. FIG. 2(b) shows a state in which the first protection control monitoring device 100A transmits sampling data in a state in which the transmission timing control means 58A resets the transmission standby period TXst to the transmission standby period TXst+α. At this time, from the viewpoint of the second protection control monitoring device 100B, it is assumed that the sampling data transmitted from the second protection control monitoring device 100B arrives at the first protection control monitoring device 100A at time t2 in FIG. 2(b), and at the same time, the sampling data transmitted from the first protection control monitoring device 100A is received at time t3 in FIG. 2(b). Therefore, the synchronization error detection means 54B detects that a synchronization error equivalent to time t3-time t2 (=α) has occurred, and the sampling synchronization means 56B delays the sampling timing SPs by α. By the above processing, as shown in FIG. 2(c), the sampling timing SPm and the sampling timing SPs coincide with each other, and sampling synchronization can be achieved between the first protection control monitoring device 100A and the second protection control monitoring device 100B.

[0018] Fig. 3 is a diagram showing an example of the flow of the operation of the transmission timing control means 58A and the sampling synchronization means 56B when the assumed transmission delay time Tdly_exp is shorter than the actual transmission delay time Tdly. Fig. 3(a) shows a situation in which the slave sampling synchronization means 56B attempts to synchronize the sampling timing SPs with the sampling timing SPm, but the assumed transmission delay time Tdly_exp is shorter than the actual transmission delay time Tdly by α, causing the sampling timing SPs to deviate backward by α from the sampling timing SPm. In other words, from the perspective of the second protection and control monitoring device 100B, at time t2 in Figure 3(a), it is assumed that the sampling data transmitted from the second protection and control monitoring device 100B has arrived at the first protection and control monitoring device 100A, and at the same time, sampling data transmitted from the first protection and control monitoring device 100A is received, so it erroneously recognizes that Tdly_exp = Tdly holds, and the sampling synchronization means 56B sets the sampling timing SPs to a position that is α behind the sampling timing SPm.

[0019] On the other hand, the measurement means 52A measures that the sampling data transmitted from the second protection and control monitoring device 100B is received at time t3 in Fig. 3(a). At this time, the first protection and control monitoring device 100A assumes that the sampling data transmitted to the second protection and control monitoring device 100B reaches the second protection and control monitoring device 100B at time t1 in Fig. 3(a). As a result, the synchronization error detection means 54A recognizes that a deviation has occurred in the reception timing for a time equivalent to time t1-time t3 (=-2α), and detects a synchronization error Tdif=Tdly_exp-Tdly=-α.

[0020] When the synchronization error detection means 54A detects a synchronization error -α, the transmission timing control means 58A resets the period TXst to the period TXst-α. FIG. 2(b) shows a state in which the first protection control monitoring device 100A transmits sampling data in a state in which the transmission timing control means 58A resets the period TXst to the period TXst-α. At this time, from the viewpoint of the second protection control monitoring device 100B, it is assumed that the sampling data transmitted from the second protection control monitoring device 100B arrives at the first protection control monitoring device 100A at time t2 in FIG. 2(b), and at the same time, the sampling data transmitted from the first protection control monitoring device 100A is received at time t1 in FIG. 2(b). Therefore, the synchronization error detection means 54B detects that a synchronization error equivalent to time t1-time t3 (=-α) has occurred, and the sampling synchronization means 56B advances the sampling timing SPs by α. By the above processing, as shown in FIG. 3(c), the sampling timing SPm and the sampling timing SPs coincide with each other, and sampling synchronization can be achieved between the first protection control monitoring device 100A and the second protection control monitoring device 100B.

[0021] 4 is a timing chart showing an example of the flow of processing executed by the first protection control monitoring device 100A and the second protection control monitoring device 100B in the first embodiment. First, the sampling synchronization means 56B of the second protection control monitoring device 100B attempts to synchronize the sampling timing SPs with the sampling timing SPm by outputting a sampling signal SS to the A / D conversion unit 20B so as to eliminate the synchronization error Tdif detected by the synchronization error detection means 54B (step S10). At this time, if the apparent synchronization error detected by the synchronization error detection means 54B matches the true synchronization error, the sampling timing SPs matches the sampling timing SPm by the processing of step S10, but if the apparent synchronization error does not match the true synchronization error as shown in FIG. 2(a) and FIG. 3(a), the sampling timing SPs deviates from the sampling timing SPm.

[0022] Next, the transmission processing unit 40B transmits the sampling data acquired at the sampling timing SPs set by the sampling synchronization means 56B to the first protection control monitoring device 100A (step S11). Next, the measurement means 52A measures the reception timing at which the sampling data transmitted from the second protection control monitoring device 100B is received (step S12). Next, the synchronization error detection means 54A detects the synchronization error α based on the time difference between the reception timing measured by the measurement means 52A and the reception timing by the second protection control monitoring device 100B of the data transmitted from the first protection control monitoring device 100A, which is assumed by the first protection control monitoring device 100A (step S13).

[0023] Next, the transmission timing control means 58A corrects the transmission standby period TXst based on the synchronization error α detected by the synchronization error detection means 54A (step S14). Next, the transmission processing unit 40A transmits the sampling data to the second protection control monitoring device 100B according to the transmission standby period TXst corrected by the transmission timing control means 58A (step S15). Next, when the measurement means 52B receives the sampling data from the first protection control monitoring device 100A, the synchronization error detection means 54B detects the synchronization error α, and the sampling synchronization means 56B outputs a sampling signal SS to the A / D conversion unit 20B so as to eliminate the synchronization error α detected by the synchronization error detection means 54B, thereby synchronizing the sampling timing SPs with the sampling timing SPm (step S16). Unlike the processing of step S10, the processing of step S16 is executed after the first protection and control monitoring device 100A, which is the master, detects the synchronization error α and corrects the transmission waiting period TXst, so that the synchronization error detection means 54B is able to recognize the true synchronization error and achieve sampling synchronization between the first protection and control monitoring device 100A and the second protection and control monitoring device 100B.

[0024] According to the first embodiment described above, unlike the conventional technology in which sampling synchronization is achieved by mutually transmitting reception timing information of sampling data, the first protection and control monitoring device 100A and the second protection and control monitoring device 100B do not mutually transmit reception timing information of sampling data, but the first protection and control monitoring device 100A detects a synchronization error α and controls the transmission timing of the sampling data to achieve sampling synchronization. In other words, sampling synchronization can be achieved even in a transmission path with a limited data transmission capacity.

[0025] Second embodiment In the first embodiment, when the synchronization error detection means 54A detects the synchronization error α, the transmission timing control means 58A corrects the transmission standby period TXst directly based on the synchronization error α. However, for example, in step S10 of FIG. 4, when the sampling synchronization means 56B is in a transient state attempting to synchronize the sampling timing SPs with the sampling timing SPm, the synchronization error α detected by the synchronization error detection means 54A may fluctuate greatly. In such a situation, the transmission timing control means 58A frequently corrects the transmission standby period TXst, and accordingly, the sampling synchronization means 56B frequently moves the sampling timing SPs, so that the operations of the first protection control monitoring device 100A and the second protection control monitoring device 100B are not stable. The second embodiment is intended to address such a problem. The functional configurations of the first protection control monitoring device 100A and the second protection control monitoring device 100B are similar to those of the first embodiment shown in FIG. 1, and therefore will not be described.

[0026] 5 is a timing chart showing an example of the flow of processing executed by the first protection and control monitoring device 100A and the second protection and control monitoring device 100B in the second embodiment. The processing contents from step S10 to step S13 are similar to the processing contents of the first embodiment shown in FIG. 4, and therefore the description thereof will be omitted.

[0027] In step S13B, when the synchronization error α is detected by the synchronization error detection means 54A, the transmission timing control means 58A judges whether the synchronization error α is within a certain fluctuation range. Specifically, the transmission timing control means 58A compares the synchronization error α1 detected in the previous sampling cycle with the synchronization error α2 detected in the current sampling cycle, and judges whether the difference |α1-α2| is within a certain fluctuation range. For example, the certain fluctuation range may be judged whether |α1-α2|≦|α1| is satisfied. More generally, a statistical value (e.g., moving average, etc.) of the synchronization errors α1, α2, . . . αN detected in a predetermined number of sampling cycles is calculated, and whether the statistical value satisfies a predetermined criterion (e.g., whether the standard deviation is within σ, etc.) may be judged whether the synchronization error α is within a certain fluctuation range. When the transmission timing control means 58A judges that the synchronization error α is within a certain fluctuation range, the transmission timing control means 58A corrects the transmission waiting period TXst based on the synchronization error α (step S14). The subsequent processing is similar to that in the timing chart of FIG. 4, and therefore the description will be omitted.

[0028] According to the second embodiment described above, the transmission timing control means 58A judges whether the synchronization error α detected by the synchronization error detection means 54A is within a certain fluctuation range, and corrects the transmission standby period TXst when the synchronization error α is within the certain fluctuation range. This makes it possible to stabilize the operations of the first protection and control monitoring device 100A and the second protection and control monitoring device 100B while achieving sampling synchronization.

[0029] Third embodiment In the first and second embodiments, the first protection and control monitoring device 100A functions as a master that controls the timing of transmitting sampling data, and the second protection and control monitoring device 100B functions as a slave that corrects the sampling timing. That is, the first protection and control monitoring device 100A does not correct the sampling timing SPm to match the second protection and control monitoring device 100B, and therefore can function as a master of multiple slave protection and control monitoring devices. The third embodiment realizes such a function.

[0030] Fig. 6 is a configuration diagram of a protection control monitoring system 2 according to the third embodiment. The protection control monitoring system 2 differs from the protection control monitoring system 1 according to the first embodiment shown in Fig. 1 in that in addition to the second protection control monitoring device 100B, the protection control monitoring system 2 includes a third protection control monitoring device 100C, ..., an Nth protection control monitoring device 100N (N is an arbitrary integer equal to or greater than 3). The first protection control monitoring device 100A includes a transmission processing unit 40A-1, a transmission processing unit 40A-2, ..., a transmission processing unit 40A-N instead of the transmission processing unit 40A, and the transmission processing unit 40A-1, the transmission processing unit 40A-2, ..., the transmission processing unit 40A-N transmit and receive sampling data between the second protection control monitoring device 100B, the third protection control monitoring device 100C, ..., and the Nth protection control monitoring device 100N, respectively.

[0031] As in the first embodiment, the synchronization error detection means 54A detects synchronization errors α1, α2, ..., αN for each of the second protection and control monitoring device 100B, the third protection and control monitoring device 100C, ..., the Nth protection and control monitoring device 100N, and the transmission timing control means 58A corrects the transmission waiting periods TXst_1, TXst_2, ..., TXst_N of the sampling data transmitted from the transmission processing unit 40A-1, transmission processing unit 40A-2, ..., transmission processing unit 40A-N based on the detected synchronization errors α1, α2, ..., αN, respectively. In response to this, the sampling synchronization means 56B, sampling synchronization means 56C, ..., sampling synchronization means 56N of the second protection and control monitoring device 100B, the third protection and control monitoring device 100C, ..., the Nth protection and control monitoring device 100N can correct the sampling timing based on the synchronization errors α1, α2, ..., αN, respectively, and achieve sampling synchronization with the first protection and control monitoring device 100A, which is the master.

[0032] According to the third embodiment described above, the protection control monitoring device functioning as a master independently controls the transmission timing of sampling data for each of the multiple protection control monitoring devices functioning as slaves based on the synchronization error detected therefor, and the multiple protection control monitoring devices functioning as slaves synchronize their respective sampling timing with the sampling timing of the protection control monitoring device functioning as a master. This makes it possible to synchronize sampling among the multiple protection control monitoring devices.

[0033] (Fourth embodiment) The first to third embodiments are applied to a transmission path in which the upstream transmission delay time and the downstream transmission delay time are the same. On the other hand, the method in which the protection control monitoring device functioning as the master controls the transmission timing of the sampling data to obtain sampling synchronization can also be applied to a transmission path in which the upstream transmission delay time Td_up and the downstream transmission delay time Td_down are different. The fourth embodiment applies the present invention to a transmission path in which the upstream transmission delay time Td_up and the downstream transmission delay time Td_down are different. The functional configuration of the fourth embodiment is the same as that of the first embodiment shown in FIG. 1, so the description will be omitted. In the fourth embodiment, it is assumed that information on the transmission delay time difference Td_down-Td_up between the upstream transmission delay time Td_up and the downstream transmission delay time Td_down is set in advance in the first protection control monitoring device 100A.

[0034] FIG. 7 is a diagram showing an example of the flow of the operation of the transmission timing control means 58A and the operation of the sampling synchronization means 56B when the upstream transmission delay time Td_up is longer than the downstream transmission delay time Td_down. In this embodiment, the transmission processing unit 40 transmits the sampling data to the other protection control monitoring device 100, including reception timing information RXtm of the sampling data received by the protection control monitoring device 100 from the other protection control monitoring device 100. The reception timing information RXtm is information indicating the period from when the protection control monitoring device 100 performs sampling in a certain sampling cycle to when the sampling data transmitted from the other protection control monitoring device 100 is received in the same sampling cycle. More specifically, as shown in FIG. 7(a), in the case of the upstream transmission delay time RXtmm, RXtmm=TXst+Td_up-Tdif is established, and in the case of the downstream transmission delay time RXtms, RXtms=TXst+Td_down+Tdif is established.

[0035] In FIG. 7(a), first, the measurement means 52A acquires the reception timing information RXtms included in the sampling data transmitted from the second protection control monitoring device 100B. On the other hand, the first protection control monitoring device 100A holds the reception timing information RXtmm that is paired with the sampling data. Next, the synchronization error detection means 54A calculates RXtms-RXtmm=TXst+Td_down+Tdif-(TXst+Td_up-Tdif)=Td_down-Td_up+2Tdif. Here, RXtms-RXtmm is a value that can be calculated from the reception timing information, and Td_down-Td_up is a known value from the above-mentioned assumption. That is, the synchronization error detection means 54A can calculate the synchronization error Tdif by Tdif={(RXtms-RXtmm)-(Td_down-Td_up)} / 2.

[0036] Next, as shown in Fig. 7(b), the transmission timing control means 58A delays the transmission standby period TXst by Tdif x 2 = α. That is, the transmission timing control means 58A resets the transmission standby period TXst to the transmission standby period TXst + α. Next, as shown in Fig. 7(c), the sampling synchronization means 56B recognizes that the reception timing information RXtmm included in the sampling data transmitted from the first protection control monitoring device 100A is delayed by α, and delays the sampling timing SPs by a period equivalent to α / 2 = Tdif. As a result, the sampling timing SPs coincides with the sampling timing SPm.

[0037] 8 is a diagram showing an example of the flow of operations of the transmission timing control means 58A and the sampling synchronization means 56B when the upstream transmission delay time Td_up is shorter than the downstream transmission delay time Td_down. As shown in FIG. 8(a), when the upstream transmission delay time RXtmm is RXtmm=TXst+Td_up+Tdif holds, and when the downstream transmission delay time RXtms is RXtms=TXst+Td_down-Tdif holds.

[0038] In FIG. 8(a), first, the measurement means 52A acquires the reception timing information RXtms included in the sampling data transmitted from the second protection control monitoring device 100B. On the other hand, the first protection control monitoring device 100A holds the reception timing information RXtmm that is paired with the sampling data. Next, the synchronization error detection means 54A calculates RXtms-RXtmm=TXst+Td_down-Tdif-(TXst+Td_up+Tdif)=Td_down-Td_up-2Tdif. Here, RXtms-RXtmm is a value that can be calculated from the reception timing information, and Td_down-Td_up is a known value from the above-mentioned assumption. That is, the synchronization error detection means 54A can calculate the synchronization error Tdif by Tdif={(Td_down-Td_up)-(RXtms-RXtmm)} / 2.

[0039] Next, as shown in Fig. 8(b), the transmission timing control means 58A advances the transmission standby period TXst by Tdif x 2 = α. That is, the transmission timing control means 58A resets the transmission standby period TXst to a transmission standby period TXst-α. Next, as shown in Fig. 8(c), the sampling synchronization means 56B recognizes that the reception timing information RXtmm included in the sampling data transmitted from the first protection control monitoring device 100A has advanced by α, and advances the sampling timing SPs by a period equivalent to α / 2 = Tdif. As a result, the sampling timing SPs coincides with the sampling timing SPm.

[0040] According to the fourth embodiment described above, in comparison with the conventional technology in which sampling synchronization is achieved by setting information about the transmission delay time difference in both the protection and control monitoring device functioning as a master and the protection and control monitoring device functioning as a slave, information about the transmission delay time difference is set only in the protection and control monitoring device functioning as a master, and the protection and control monitoring device achieves sampling synchronization by controlling the transmission timing of sampling data based on the set transmission delay time difference and reception timing information. This makes it possible to save the effort of setting information about the transmission delay time difference in multiple protection and control monitoring devices.

[0041] Fifth embodiment In the fourth embodiment, the first protection control monitoring device 100A functions as a master that controls the transmission timing of sampling data, and the second protection control monitoring device 100B functions as a slave that corrects the sampling timing. That is, the first protection control monitoring device 100A does not correct the sampling timing according to the second protection control monitoring device 100B, so it can function as a master of multiple slave protection control monitoring devices. The fifth embodiment realizes such a function. The functional configuration of the fifth embodiment is similar to the functional configuration of the third embodiment shown in FIG. 6, so the description will be omitted. Also, as in the fourth embodiment, it is assumed that information on the transmission delay time difference Td_down-Td_up between the upstream transmission delay time Td_up and the downstream transmission delay time Td_down is set in advance for each of the second protection control monitoring device 100B, the third protection control monitoring device 100C, ..., and the Nth protection control monitoring device 100N in the first protection control monitoring device 100A.

[0042] The synchronization error detection means 54A calculates the synchronization error Tdif for each of the second protection control monitoring device 100B, the third protection control monitoring device 100C, ..., the Nth protection control monitoring device 100N based on the reception timing information RXtms transmitted from each of the second protection control monitoring device 100B, the third protection control monitoring device 100C, ..., the Nth protection control monitoring device 100N and a preset transmission delay time difference Td_down-Td_up. Next, the transmission timing control means 58A corrects the transmission standby periods TXst_1, TXst_2, ..., TXst_N of the sampling data transmitted from the transmission processing unit 40A-1, the transmission processing unit 40A-2, ..., the transmission processing unit 40A-N based on the calculated synchronization error Tdif. In response to this, the sampling synchronization means 56B, sampling synchronization means 56C, ..., sampling synchronization means 56N of the second protection and control monitoring device 100B, the third protection and control monitoring device 100C, ..., the Nth protection and control monitoring device 100N can correct the sampling timing and achieve sampling synchronization with the first protection and control monitoring device 100A, which is the master.

[0043] According to the fifth embodiment described above, the protection control monitoring device functioning as a master independently controls the transmission timing of sampling data based on the synchronization errors calculated for each of the multiple protection control monitoring devices functioning as slaves, and the multiple protection control monitoring devices functioning as slaves synchronize their respective sampling timing with the sampling timing of the protection control monitoring device functioning as a master. This makes it possible to achieve sampling synchronization between the multiple protection control monitoring devices while saving the effort of setting information about the transmission delay time difference in the multiple protection control monitoring devices.

[0044] Sixth embodiment In the fourth embodiment, the transmission timing control means 58A controls the transmission timing of the sampling data according to the synchronization error detected by the synchronization error detection means 54A. However, the present invention is not limited to such a configuration, and in a sixth embodiment, the first protection and control monitoring device 100A may correct the reception timing information to be notified to the second protection and control monitoring device 100B without changing the transmission timing of the sampling data. The other configurations are the same as those in the fourth embodiment, and therefore the description will be omitted.

[0045] FIG. 9 is a diagram for explaining a method of obtaining sampling synchronization by correcting the reception timing information notified by the first protection control monitoring device 100A to the second protection control monitoring device 100B. FIG. 9(a) shows the correction of the reception timing information when the upstream transmission delay time is longer than the downstream transmission delay time, and FIG. 9(b) shows the correction of the reception timing information when the upstream transmission delay time is shorter than the downstream transmission delay time. In the case of FIG. 9(a), instead of correcting the transmission waiting period TXst by Tdif×2=α, the first protection control monitoring device 100A notifies the second protection control monitoring device 100B of the reception timing information RXtmm+α obtained by adding α to the value of the reception timing information RXtmm notified to the second protection control monitoring device 100B. The second protection control monitoring device 100B recognizes that the reception timing information RXtmm included in the sampling data transmitted from the first protection control monitoring device 100A is delayed by α, and delays the sampling timing SPs by a period equivalent to α / 2=Tdif. This allows sampling synchronization. Also, in the case of Fig. 9(b), the first protection control monitoring device 100A, instead of correcting the transmission standby period TXst by Tdif x 2 = α, notifies the second protection control monitoring device 100B of the reception timing information RXtmm-α obtained by subtracting α from the value of the reception timing information RXtmm to be notified to the second protection control monitoring device 100B. The second protection control monitoring device 100B recognizes that the reception timing information RXtmm included in the sampling data transmitted from the first protection control monitoring device 100A has advanced by α, and advances the sampling timing SPs by a period equivalent to α / 2 = Tdif. This allows sampling synchronization.

[0046] According to the sixth embodiment described above, sampling synchronization can be achieved by a simple process of changing the contents of the reception timing information to be notified to the second protection control monitoring device 100B, without controlling the transmission timing of the sampling data by the transmission timing control means 58A.

[0047] Seventh embodiment In the sixth embodiment, the first protection control monitoring device 100A functions as a master that corrects the reception timing information, and the second protection control monitoring device 100B functions as a slave that corrects the sampling timing. That is, the first protection control monitoring device 100A does not correct the sampling timing according to the second protection control monitoring device 100B, so it can function as a master of multiple slave protection control monitoring devices. The seventh embodiment realizes such a function. The functional configuration of the seventh embodiment is similar to that of the fifth embodiment, so a description thereof will be omitted.

[0048] The synchronization error detection means 54A calculates the synchronization error Tdif for each of the second protection and control monitoring device 100B, the third protection and control monitoring device 100C, ..., the Nth protection and control monitoring device 100N based on the reception timing information RXtms transmitted from each of the second protection and control monitoring device 100B, the third protection and control monitoring device 100C, ..., the Nth protection and control monitoring device 100N and a predetermined transmission delay time difference Td_down-Td_up. Next, the transmission processing unit 40A-1, the transmission processing unit 40A-2, ..., the transmission processing unit 40A-N notify the second protection control monitoring device 100B, the third protection control monitoring device 100C, ..., the Nth protection control monitoring device 100N of the reception timing information RXtmm+α obtained by adding Tdif×2=α to the value of the reception timing information to be notified to the second protection control monitoring device 100B, the third protection control monitoring device 100C, ..., the Nth protection control monitoring device 100N based on the calculated synchronization error Tdif. In response to this, the sampling synchronization means 56B, the sampling synchronization means 56C, ..., the sampling synchronization means 56N of the second protection control monitoring device 100B, the third protection control monitoring device 100C, ..., the Nth protection control monitoring device 100N can correct the sampling timing and achieve sampling synchronization with the first protection control monitoring device 100A, which is the master.

[0049] According to the seventh embodiment described above, in comparison with the conventional technology in which sampling synchronization is achieved by setting information about the transmission delay time difference in both the protection and control monitoring device functioning as a master and the protection and control monitoring device functioning as a slave, information about the transmission delay time difference is set only in the protection and control monitoring device functioning as a master, and the protection and control monitoring device achieves sampling synchronization by changing the contents of the reception timing information to be notified to the other protection and control monitoring devices. This makes it possible to achieve sampling synchronization by simple processing while saving the effort of setting information about the transmission delay time difference in multiple protection and control monitoring devices.

[0050] Eighth embodiment The first to seventh embodiments relate to a case where the sampling synchronization means 56 of the protection control monitoring device 100 achieves sampling synchronization only through a transmission line. However, the present invention is not limited to such a configuration. The seventh embodiment relates to a case where the sampling synchronization means 56 of the protection control monitoring device 100 achieves sampling synchronization via an external time synchronization source.

[0051] Fig. 10 is a configuration diagram of a protection control monitoring system 3 according to the eighth embodiment. As shown in Fig. 10, a sampling synchronization means 56A and a sampling synchronization means 56B perform sampling synchronization based on a sampling synchronization signal from an external time synchronization source 200, which is, for example, a GPS satellite. The other configurations are similar to the functional configurations shown in Fig. 1, and therefore description thereof will be omitted.

[0052] When the sampling synchronization means 56A or the sampling synchronization means 56B fails to acquire a sampling synchronization signal from the external time synchronization source 200, the sampling synchronization means 56A and the sampling synchronization means 56B establish sampling synchronization via a transmission line using the method described in the first, fourth, or sixth embodiment. More specifically, when the transmission capacity of the transmission line between the sampling synchronization means 56A and the sampling synchronization means 56B is low, the first protection control monitoring device 100A can establish sampling synchronization by detecting a synchronization error with the second protection control monitoring device 100B without using reception timing information and controlling the transmission timing of the sampling data based on the synchronization error. In addition, when the transmission capacity of the transmission path between the sampling synchronization means 56A and the sampling synchronization means 56B is not low and information regarding the transmission delay time difference with the second protection control monitoring device 100B is set in the first protection control monitoring device 100A, the first protection control monitoring device 100A can detect a synchronization error using the reception timing information and the information regarding the transmission delay time difference, and achieve sampling synchronization by either controlling the transmission timing of the sampling data based on the synchronization error, or correcting the reception timing information to be transmitted to the second protection control monitoring device 100B.

[0053] According to the eighth embodiment described above, even if multiple protection control monitoring devices perform sampling synchronization via an external time synchronization source, if there is any malfunction in the external time synchronization source, sampling synchronization can be achieved via the transmission path.

[0054] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention.

Claims

1. A first protection and control monitoring device having a measurement unit that measures a reception timing of data transmitted from a communication destination and an adjustment unit that adjusts a transmission timing of transmitting data to the communication destination; a second protection and control monitoring device having a measurement unit that measures a reception timing of data transmitted from a communication destination and a correction unit that corrects a sampling timing of the data; The adjustment unit of the first protection and control monitoring device adjusts the transmission timing based on a time difference between the reception timing of the data transmitted from the second protection and control monitoring device measured by the measurement unit of the first protection and control monitoring device and the reception timing by the second protection and control monitoring device of the data transmitted from the first protection and control monitoring device assumed by the first protection and control monitoring device; The correction unit of the second protection and control monitoring device corrects the sampling timing after the adjustment unit of the first protection and control monitoring device adjusts the transmission timing, thereby achieving sampling synchronization between the first protection and control monitoring device and the second protection and control monitoring device. Protection control monitoring system.

2. The adjustment unit of the first protection and control monitoring device adjusts the transmission timing when the reception timing of the data transmitted from the second protection and control monitoring device measured by the measurement unit of the first protection and control monitoring device is within a certain fluctuation range.

2. The protection control monitoring system of claim 1.

3. A plurality of the second protection and control monitoring devices are provided, The adjustment unit of the first protection and control monitoring device independently adjusts the transmission timings for the second protection and control monitoring devices. A protection control monitoring system according to claim 1 or 2.

4. The data transmitted from the first protection and control monitoring device to the second protection and control monitoring device does not include reception timing information at which the first protection and control monitoring device received the data transmitted from the second protection and control monitoring device, The data transmitted from the second protection and control monitoring device to the first protection and control monitoring device does not include reception timing information at which the first protection and control monitoring device received the data transmitted from the second protection and control monitoring device. A protection control monitoring system according to any one of claims 1 to 3.

5. A first protection and control monitoring device having a measurement unit that measures a reception timing of data transmitted from a communication destination, a transmission unit that transmits data including the measured reception timing information, and an adjustment unit that adjusts a transmission timing of transmitting the data to the communication destination; a second protection and control monitoring device having a measurement unit that measures a reception timing of data transmitted from a communication destination and a correction unit that corrects a sampling timing of the data; The adjustment unit of the first protection and control monitoring device adjusts the transmission timing according to a difference between an upstream transmission delay time and a downstream transmission delay time of a transmission path between the first protection and control monitoring device and the second protection and control monitoring device, The correction unit of the second protection and control monitoring device corrects the sampling timing based on the reception timing information included in the data transmitted by the transmission unit of the first protection and control monitoring device, thereby achieving sampling synchronization between the first protection and control monitoring device and the second protection and control monitoring device. Protection control monitoring system.

6. A plurality of the second protection and control monitoring devices are provided, The adjustment unit of the first protection and control monitoring device independently adjusts the transmission timings for the second protection and control monitoring devices. The protection control monitoring system according to claim 5.

7. A measurement unit that measures a reception timing of data transmitted from a communication destination; A transmission unit that transmits data including the measured reception timing information; A first protection and control monitoring device having at least an adjustment unit that adjusts reception timing information included in the data to be transmitted to a communication destination; A measurement unit that measures a reception timing of data transmitted from a communication destination; A correction unit that corrects a sampling timing of data; and a second protection and control monitoring device having at least the following: The adjustment unit of the first protection and control monitoring device adjusts the reception timing information according to a difference between an upstream transmission delay time and a downstream transmission delay time of a transmission path between the first protection and control monitoring device and the second protection and control monitoring device, The correction unit of the second protection and control monitoring device corrects the sampling timing based on the reception timing information included in the data transmitted by the transmission unit of the first protection and control monitoring device, thereby achieving sampling synchronization between the first protection and control monitoring device and the second protection and control monitoring device. Protection control monitoring system.

8. A plurality of the second protection and control monitoring devices are provided, The adjustment unit of the first protection and control monitoring device independently adjusts the plurality of pieces of reception timing information for the plurality of second protection and control monitoring devices. The protection control monitoring system according to claim 7.

9. The first protection control monitoring device and the second protection control monitoring device are connected to a sampling synchronization source; When a connection between at least one of the first protection control monitoring device and the second protection control monitoring device and the sampling synchronization source is disconnected, the first protection control monitoring device and the second protection control monitoring device perform the sampling synchronization. A protection control monitoring system according to any one of claims 1 to 8.

10. A measurement unit that measures a reception timing of data transmitted from a communication destination; an adjustment unit that adjusts a transmission timing for transmitting data to a communication destination; A protection control monitoring device comprising: In order to synchronize sampling with a second protection and control monitoring device having a measurement unit that measures the reception timing of data transmitted from a communication destination and a correction unit that corrects the sampling timing of the data, The adjustment unit adjusts the transmission timing based on a time difference between the reception timing of the data transmitted from the second protection and control monitoring device measured by the measurement unit of the protection and control monitoring device and the reception timing by the second protection and control monitoring device of the data transmitted from the protection and control monitoring device assumed by the protection and control monitoring device. Protection control monitoring equipment.

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