Protection relay system

Abstract

To provide a protection relay system capable of properly communicating electricity amount data and accident analysis data of a plurality of relay devices by using the same network.SOLUTION: A protection relay system includes: a plurality of network switches; a plurality of relay devices connected to each network switch; and an analysis device and a management device, which are connected to any one of the plurality of network switches. The management device collects reception information of data in each network switch. The analysis device transmits a first transmission request of accident analysis data with respect to the plurality of first relay devices to the management device. The management device generates a plurality of second transmission requests based on reception information in response to the first transmission request from the analysis device, and sequentially transmits the plurality of generated second transmission requests to each first relay device. Each first relay device transmits accident analysis data to the analysis device according to the received second transmission request.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a protective relay system. [Background technology]

[0002] For example, JP 2014-138454 A (Patent Document 1) discloses a protective relay system that protects a power transmission line. This protective relay system includes a plurality of protective relay devices that protect a power system based on electrical quantity data of the power system. Each protective relay device is connected to a current transformer installed at each terminal of the power transmission line section, and acquires electrical quantity data. Each protective relay device transmits and receives frames including electrical quantity data to and from other protective relay devices via a network. The electrical quantity data is used for current differential calculation in each protective relay device, and therefore needs to be transmitted at a high speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-138454 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned protective relay system, when an accident occurs in a power transmission line section, data related to the accident may be requested from each relay device in order to perform an accident analysis. The accident analysis data is, for example, electric quantity data related to the power transmission line for a certain period before and after the accident and calculation data based on the electric quantity data, and the amount of data is larger than the amount of electric quantity data transmitted and received between other protective relay devices.

[0005] By configuring each relay device to send and receive fault analysis data via the same network as electrical quantity data, there is no need to construct a network dedicated to fault analysis data, thereby reducing the total cost of the protective relay system.

[0006] However, in the above configuration, the timing of arrival of fault analysis data is concentrated in a short period of time in a network switch provided at any of the terminals, which may cause congestion of the fault analysis data. If congestion of the fault analysis data occurs, it may cause a delay in the timing of reception of the electric quantity data by the network switch. If the timing of reception of the electric quantity data is delayed, each protective relay device will not be able to properly perform current differential calculation, which may impair the protection function of the power transmission line.

[0007] An object of one aspect of the present disclosure is to provide a technology that enables, in a protective relay system including a plurality of relay devices, normal communication of electrical quantity data of the plurality of relay devices and accident analysis data related to an accident that has occurred in a protection section using the same network. [Means for solving the problem]

[0008] A protective relay system according to an embodiment includes a plurality of network switches provided at a plurality of terminals, a plurality of relay devices connected to each of the plurality of network switches connected in a loop, an analysis device connected to one of the plurality of network switches, and a management device connected to one of the plurality of network switches. For each of the plurality of network switches, each of the plurality of relay devices connected to the network switch transmits electric quantity data measured at a sampling timing to the network switch. Each network switch transmits the received electric quantity data to another network switch. The management device collects reception information of data including the electric quantity data in each network switch. When an accident occurs in a power transmission line protected by a first relay device among the plurality of relay devices, the analysis device transmits a first transmission request for accident analysis data to the management device to the plurality of first relay devices. In response to the first transmission request from the analysis device, the management device generates a plurality of second transmission requests based on the reception information. The management device transmits the generated second transmission requests to each of the first relay devices in order. Each of the first relay devices transmits accident analysis data to the analysis device according to the received second transmission request. Effect of the Invention

[0009] According to the present disclosure, in a protective relay system including a plurality of relay devices, electrical quantity data of the plurality of relay devices and accident analysis data related to an accident that has occurred in a protection section can be normally communicated using the same network. [Brief description of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram of a protection relay system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a block diagram showing an example of a hardware configuration of a relay device. [Diagram 3] FIG. 2 is a block diagram showing an example of a hardware configuration of an analysis device. [Figure 4] FIG. 11 is a sequence diagram illustrating an example of a time synchronization method. [Diagram 5] 4 is a timing chart for explaining frame transmission timing of the relay device. [Figure 6] 10A and 10B are diagrams for explaining the arrival timing of a frame at a switch according to the present embodiment. [Figure 7] FIG. 13 is a diagram for explaining the arrival timing of a frame at a fifth switch. [Figure 8] FIG. 13 is a diagram showing a state in which offline data is transmitted to an analysis device. [Figure 9] FIG. 11 is a sequence diagram illustrating an offline data transmission process in the protection relay system. [Figure 10] 10 is a diagram for explaining the storage process (P21 in FIG. 9) of frame reception information in each switch. [Figure 11] 10 is a sequence diagram illustrating the process of collecting frame reception information in the management device (P11 in FIG. 9). [Figure 12] 11 is a diagram for explaining a transmission delay time in a request destination relay device; [Figure 13] 11A and 11B are diagrams for explaining a method of calculating a transmission delay time and the number of pieces of transmission data. [Figure 14] 11 is a flowchart showing a process flow in the analysis device. [Figure 15] 10 is a flowchart showing a process flow in a management device. [Figure 16] 16 is a flowchart showing a process flow in a relay device having device number Y in FIG. 15. [Figure 17] FIG. 13 is a diagram for explaining the arrival timing of a frame at a fifth switch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. The names and functions of the components are also the same. Therefore, detailed description thereof will not be repeated.

[0012] <Overall composition> 1 is an overall configuration diagram of a protection relay system according to an embodiment of the present disclosure. As shown in FIG. 1, a protection relay system 1000 includes network switches 3_1-3_5 (hereinafter also collectively referred to as "switches 3"), a plurality of relay devices 2_1-2_20 (hereinafter also collectively referred to as "relay devices 2"), a plurality of monitoring devices 5_1-5_5 (hereinafter also collectively referred to as "monitoring devices 5"), a synchronization device 20, an analysis device 60, and a management device 80.

[0013] In the present embodiment, a configuration in which the synchronization device 20 is connected to the first switch 3_1 will be described, but the synchronization device 20 may be connected to any of the other switches 3_2 to 3_5. Also, a configuration in which the analysis device 60 and the management device 80 are connected to the fifth switch 3_5 will be described, but each of the analysis device 60 and the management device 80 may be connected to any of the other switches 3_1 to 3_4. The analysis device 60 and the management device 80 may be connected to different switches 3.

[0014] The network NW used in the protection relay system 1000 shown in Fig. 1 is configured by interconnecting 20 relay devices 2_1 to 2_20 using five switches 3_1 to 3_5. The multiple switches 3_1 to 3_5 are provided at multiple terminals (e.g., electric power stations) E1 to E5, respectively. The multiple switches 3_1 to 3_5 are connected in a loop shape via a communication path R. The network NW is configured, for example, by a high-speed communication network such as Ethernet (registered trademark). Each switch 3 is, for example, an L3 switch.

[0015] A plurality of relay devices 2 (i.e., first to fourth relay devices) and a monitoring device 5 are connected to each switch 3. For example, a first switch 3_1, a first relay device 2_1, a second relay device 2_2, a third relay device 2_3, a fourth relay device 2_4, and a first monitoring device 5_1 connected to the first switch 3_1, and a synchronizing device 20 are provided at the terminal E1.

[0016] The terminal E2 is provided with a second switch 3_2, and a first relay device 2_5, a second relay device 2_6, a third relay device 2_7, a fourth relay device 2_8 and a second monitoring device 5_2, which are connected to the second switch 3_2.

[0017] The terminal E3 is provided with a third switch 3_3, and a first relay device 2_9, a second relay device 2_10, a third relay device 2_11, a fourth relay device 2_12 and a third monitoring device 5_3, which are connected to the third switch 3_3.

[0018] The terminal E4 is provided with a fourth switch 3_4, and a first relay device 2_13, a second relay device 2_14, a third relay device 2_15, a fourth relay device 2_16 and a fourth monitoring device 5_4 connected to the fourth switch 3_4.

[0019] Terminal E5 is provided with a third switch 3_5, a first relay device 2_17, a second relay device 2_18, a third relay device 2_19, a fourth relay device 2_20, a fifth monitoring device 5_5, an analysis device 60 and a management device 80 connected to the third switch 3_5.

[0020] (Relay device 2) Each relay device 2 is a digital type protective relay device, for example, a current differential relay device for protecting a protection section by performing a current differential calculation. In this embodiment, each of the first relay devices 2_1, 2_5, 2_9, 2_13, and 2_17 (hereinafter also collectively referred to as "first relay devices 2") is a current differential relay device for protecting a first power transmission line. Similarly, each of the second relay devices 2_2, 2_6, 2_10, 2_14, and 2_18 (hereinafter also collectively referred to as "second relay devices 2") protects a second power transmission line, each of the third relay devices 2_3, 2_7, 2_11, 2_15, and 2_19 (hereinafter also collectively referred to as "third relay devices 2") protects a third power transmission line, and each of the fourth relay devices 2_4, 2_8, 2_12, 2_16, and 2_20 (hereinafter also collectively referred to as "fourth relay devices 2") protects a fourth power transmission line.

[0021] Each relay device 2 measures electric quantity data (e.g., current data, voltage data) and transmits and receives frames including the electric quantity data to and from other relay devices 2 connected to each switch 3 on the communication path R. As a result, each relay device 2 shares the electric quantity data measured by the other relay devices 2 protecting the same power transmission line. Specifically, each first relay device 2 shares the electric quantity data measured by the other first relay devices 2 protecting the first power transmission line. Similarly, each second relay device 2 shares the electric quantity data measured by the other second relay devices 2 protecting the second power transmission line, each third relay device 2 shares the electric quantity data measured by the other third relay devices 2 protecting the third power transmission line, and each fourth relay device 2 shares the electric quantity data measured by the other fourth relay devices 2 protecting the fourth power transmission line.

[0022] Each relay device 2 generates a frame including electrical quantity data measured at its own terminal, and transmits the generated frame to the switch 3 connected to the relay device 2. Specifically, each first relay device 2 transmits a frame F1 including electrical quantity data M1 measured at its own terminal to the switch 3. Each second relay device 2 transmits a frame F2 including electrical quantity data M2 measured at its own terminal to the switch 3. Each third relay device 2 transmits a frame F3 including electrical quantity data M3 measured at its own terminal to the switch 3. Each fourth relay device 2 transmits a frame F4 including electrical quantity data M4 measured at its own terminal to the switch 3.

[0023] Each relay device 2 stores in an internal memory the electric quantity data measured at its own terminal and the calculation data based on the electric quantity data. The calculation data is, for example, power data calculated based on the voltage data and current data measured at its own terminal, frequency data calculated based on the voltage data for a specified period, etc.

[0024] (Switch 3) Each switch 3 sequentially transmits the received frames F1 to F4 to the other switches 3 via the communication path R. Specifically, the first switch 3_1 transmits the frames F1 to F4 to the second switch 3_2. The second switch 3_2 transmits the frames F1 to F4 to the first switch 3_1 and the third switch 3_3. The same applies to the switches 3_3 to 3_5.

[0025] Although details will be described later, in this embodiment, the timing of transmitting frames from each relay device 2 to the switch 3 is managed. Therefore, data can be normally transmitted and received via the communication path R without imposing a load on each switch 3 that exceeds its specifications.

[0026] A backup communication path is prepared between the first switch 3_1 and the fifth switch 3_5. For example, when the communication path R between the fourth switch 3_4 and the fifth switch 3_5 becomes unable to communicate due to a failure, the communication path R between the fourth switch 3_4 and the fifth switch 3_5 becomes a new backup communication path. Then, the switches 3 are communicatively connected in a loop shape using the original backup communication path or the like.

[0027] (Synchronizer 20) The synchronizer 20 transmits and receives synchronization messages to and from each relay device 2 for synchronizing the time of each relay device 2 with the time of the synchronizer 20. This synchronizes the time of all relay devices 2 in the protection relay system 1000. Each relay device 2 performs calculations such as fault detection and determination using electrical quantity data measured at the same time (i.e., sampling timing). The timing for measuring the electrical quantity data is determined based on a sampling pulse signal generated by dividing the hardware clock. For example, the sampling period is set to an electrical angle of 30° of the system frequency (for example, 1670 μs in the case of a 50 Hz system).

[0028] Typically, each relay device 2 performs a current differential calculation using electrical quantity data (current data in this case) sampled at each terminal. The first relay device protects the first power transmission line by performing a current differential calculation using electrical quantity data M1 sampled at its own terminal and electrical quantity data M1 sampled at one or more other terminals. The second relay device protects the second power transmission line by performing a current differential calculation using electrical quantity data M2 sampled at its own terminal and electrical quantity data M2 sampled at one or more other terminals. The same applies to the third and fourth relay devices.

[0029] As an example, a current differential method by each of the first relay devices 2 protecting the first transmission line will be described. The current data measured by the first relay devices 2_1, 2_5, 2_9, 2_13, and 2_17 are respectively set as current data I1, I5, I9, I13, and I17. In this case, each of the first relay devices 2 calculates a vector sum of each of the current data I1, I5, I9, I13, and I17, and calculates the magnitude of the calculated vector sum as a differential current IDL. Each of the first relay devices 2 determines whether or not the differential current IDL is greater than a threshold value K (i.e., whether or not IDL>K is established). If IDL>K is established, each of the first relay devices 2 determines that a fault has occurred in the protection section (i.e., the first transmission line), and outputs a trip command TR to a circuit breaker provided on the first transmission line.

[0030] Furthermore, each first relay device outputs a notification that a fault has occurred on the first power transmission line to the corresponding switch 3. Each switch 3 transmits the notification output from each first relay device to the fifth switch 3_5 via the communication path R. The fifth switch 3_5 transmits the received notification to the analysis device 60. This allows the analysis device 60 to know that a fault has occurred in a protection section (for example, any of the first to fourth power transmission lines).

[0031] (Monitoring device 5) The monitoring device 5 sequentially stores the electric quantity data measured at the synchronized sampling timing. The monitoring device 5 also executes necessary calculations on the electric quantity data and sequentially stores the calculation data. Typically, the monitoring device 5 measures electric quantity data corresponding to the electric quantity data measured by the first to fourth relay devices, and stores the electric quantity data and the calculation data as monitoring data. The monitoring device 5 transmits a frame FX including the monitoring data (for example, at least one of the electric quantity data of the first to fourth power transmission lines and the calculation data based on each electric quantity data) to the other monitoring devices 5 via the corresponding switch 3.

[0032] Each monitoring device 5 has a function of displaying monitoring data including electric quantity data (e.g., current data, voltage data), calculation data based on the electric quantity data (e.g., active power data, reactive power data, frequency data), etc. This allows a user of each monitoring device 5 (e.g., a system operator) to check the monitoring data of the device itself and the other monitoring devices 5.

[0033] (Analysis device 60) When an accident occurs in a protection section (for example, any of the first to fourth power lines), the analysis device 60 executes an accident analysis. Specifically, when the analysis device 60 receives a notification that an accident has occurred from at least one of the relay devices 2, the analysis device 60 requests data related to the accident from the at least one relay device 2.

[0034] For example, assume that an accident occurs on the first power transmission line. In this case, when the analysis device 60 receives a notification that an accident has occurred from at least one first relay device, it requests the at least one first relay device to transmit, as accident analysis data, electric quantity data and calculation data related to the first power transmission line for a certain period before and after the accident. The first relay device that receives the request transmits a frame FY including the accident analysis data to the analysis device 60 via the corresponding switch 3. In this embodiment, the accident analysis data is also referred to as "offline data" because it is data used for offline accident analysis.

[0035] (Management device 80) The management device 80 manages the timing of frame transmission in each relay device 2. As will be described in detail later, the management device 80 collects frame reception information in each switch 3. Then, based on the collected reception information, the management device 80 manages the timing of transmission of a frame FY including accident analysis data (offline data) from each relay device 2 to the switch 3 as requested by the analysis device 60, thereby preventing congestion of the frame FY arriving at the fifth switch 3_5 to which the analysis device 60 is connected. This makes it possible to transmit and receive the frames F1 to F4 including the electricity quantity data measured by each relay device 2 and the frame FY including the offline data using a common network NW.

[0036] <Hardware configuration> Each relay device 2 is configured, for example, based on a microcomputer. Each relay device 2 may be configured based on an electronic circuit such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). Alternatively, each relay device 2 may be configured by combining an electronic circuit such as an FPGA or an ASIC with a microcomputer.

[0037] Fig. 2 is a block diagram showing an example of a hardware configuration of the relay device 2. As shown in Fig. 2, the relay device 2 includes an auxiliary transformer 32, an A / D conversion unit 35, an arithmetic processing unit 40, a sampling pulse generating circuit 45, a communication circuit 50, a digital output circuit (D / O: Digital Output) 55, and a digital input circuit (D / I: Digital Input) 56.

[0038] The auxiliary transformer 32 receives an electric quantity from a current transformer or a voltage transformer (not shown), converts it to a voltage suitable for signal processing in the relay internal circuit, and outputs it. The A / D conversion unit 35 receives the voltage output from the auxiliary transformer 32 and converts it into digital data. Specifically, the A / D conversion unit 35 includes an analog filter, a sample-and-hold circuit, a multiplexer, and an A / D converter.

[0039] The analog filter removes high-frequency noise components from the current waveform signal output from auxiliary transformer 32. The sample-and-hold circuit samples the current waveform signal output from the analog filter at the period of the sampling pulse generated by sampling pulse generating circuit 45 (i.e., the sampling period). Based on the timing signal input from arithmetic processing unit 40, the multiplexer sequentially switches the waveform signals input from the sample-and-hold circuit in time series and inputs them to the A / D converter. The A / D converter outputs the digitally converted waveform signal (i.e., digital data) to arithmetic processing unit 40.

[0040] The arithmetic processing unit 40 includes a CPU (Central Processing Unit) 41, a RAM (Random Access Memory) 42, and a ROM (Read Only Memory) 43. These elements are connected to each other via a bus 44. The arithmetic processing unit 40 may include an electrically rewritable non-volatile memory such as a flash memory. The RAM 42 and the ROM 43 are used as main storage units of the CPU 41. The CPU 41 controls the operation of the entire relay device 2 according to programs stored in the ROM 43 and the non-volatile memory. Typically, each process of the relay device 2 is executed by the arithmetic processing unit 40.

[0041] The sampling pulse generating circuit 45 includes an oscillator and a frequency divider circuit. The oscillator outputs a reference frequency signal having a reference frequency for generating a sampling pulse. The frequency divider circuit divides the reference frequency signal input from the oscillator by a frequency division ratio n to generate a sampling pulse. The frequency division ratio n of the frequency divider is controlled by the CPU 41. This controls the frequency of the sampling pulse (i.e., the sampling frequency).

[0042] The communication circuit 50 communicates with the switch 3. The communication circuit 50 communicates with the switch 3 in accordance with a prescribed protocol.

[0043] The digital output circuit 55 is an interface circuit for outputting a signal to an external device. For example, the digital output circuit 55 is provided on the power transmission line and outputs a trip command TR to a circuit breaker in accordance with a command from the CPU 41. The digital input circuit 56 receives, for example, switching information indicating the open / closed state of the circuit breaker from the circuit breaker.

[0044] FIG. 3 is a block diagram showing an example of a hardware configuration of the analysis device 60. As shown in FIG. 3, the analysis device 60 includes a calculation processing unit 70 and a communication circuit 75. The calculation processing unit 70 includes a CPU 71, a RAM 72, and a ROM 73. These elements are connected to each other via a bus 74. The calculation processing unit 70 may include an electrically rewritable non-volatile memory such as a flash memory. The RAM 72 and the ROM 73 are used as the main memory of the CPU 71. The CPU 71 controls the operation of the entire analysis device 60 according to the programs stored in the ROM 73 and the non-volatile memory. Typically, each process of the analysis device 60 is executed by the calculation processing unit 70.

[0045] The communication circuit 75 communicates with each relay device 2 and the management device 80. The communication circuit 75 communicates with each relay device 2 and the management device 80 in accordance with a prescribed protocol.

[0046] The management device 80 has the same hardware configuration as the analysis device 60. Each of the analysis device 60 and the management device 80 may be configured based on an electronic circuit such as an FPGA or an ASIC instead of a configuration based on a microcomputer. Alternatively, each of the analysis device 60 and the management device 80 may be configured by combining an electronic circuit such as an FPGA or an ASIC with a microcomputer.

[0047] <Time synchronization method> Fig. 4 is a sequence diagram showing an example of a time synchronization method. The process shown in Fig. 4 is a time synchronization method conforming to IEEE 1588. The synchronization device 20 executes the process shown in Fig. 4 with each relay device 2.

[0048] 4, the synchronization device 20 transmits a Sync message, which is a synchronization frame for executing time synchronization control, to the relay device 2 (sequence SQ2). The synchronization device 20 stores the time k1 at which the Sync message was transmitted in an internal memory. The relay device 2 receives the Sync message and stores the time k2 at which the message was received in an internal memory.

[0049] The synchronization device 20 reads the time k1 at which the Sync message was transmitted from the internal memory, and transmits a Follow_Up message storing the time k1 to the relay device 2 (sequence SQ4). The relay device 2 stores the time k1 stored in the received Follow_Up message in the internal memory. Note that the synchronization device 20 may be configured to transmit the Sync message storing the time k1 to the relay device 2.

[0050] Relay device 2 transmits a Delay_Req message to synchronization device 20 (sequence SQ6). Relay device 2 stores the time k3 at which it transmitted the Delay_Req message in its internal memory. Synchronization device 20 receives the Delay_Req message and stores the time k4 at which it was received in its internal memory.

[0051] Synchronization device 20 transmits a Delay_Resp message storing time k4 to relay device 2 (sequence SQ8). Relay device 2 stores time k4 stored in the received Delay_Resp message in its internal memory.

[0052] Through the above-described sequence, times k1, k2, k3, and k4 are stored in the internal memory of the relay device 2. The relay device 2 calculates the difference (k2-k1) between time k1 and time k2 to obtain the sum of the time differences and the transmission line delay of the synchronizer 20 and the relay device 2 for the transmission line from the synchronizer 20 to the relay device 2. The relay device 2 also calculates the difference (k4-k3) between time k3 and time k4 to obtain the sum of the time differences and the transmission line delay of the synchronizer 20 and the relay device 2 for the transmission line from the relay device 2 to the synchronizer 20.

[0053] Furthermore, the sum of the time difference (k4-k3) and the time difference (k2-k1) corresponds to twice the transmission path delay. The difference between the time difference (k4-k3) and the time difference (k2-k1) corresponds to twice the time difference between the time of the synchronizer 20 and the time of the relay device 2. Here, it is assumed that the transmission delay between the synchronizer 20 and the relay device 2 is equivalent on the forward path and the return path. In this case, the delay time tx of the unidirectional transmission path is expressed as in the following equation (1). tx={(k4-k3)+(k2-k1)} / 2 ···(1) Moreover, the time difference td between the time of the synchronizer 20 and the time of the relay device 2 is expressed as in the following equation (2). td={(k4-k3)-(k2-k1)} / 2 ···(2) The relay device 2 corrects its own time using the time difference td as a correction amount for time synchronization, thereby performing time synchronization with the synchronization device 20. As a result, the time of the synchronization device 20 and the time of the relay device 2 are synchronized (i.e., matched).

[0054] Each relay device 2 synchronizes the time of the relay device 2 with the time of the synchronization device 20 based on the time synchronization data received from the synchronization device 20 via the corresponding switch 3. This allows each relay device 2 to synchronize its own sampling timing with the sampling timing of the other relay devices 2. As a result, the sampling timings of all of the relay devices 2_1 to 2_20 are synchronized.

[0055] <Frame transmission method> Fig. 5 is a timing chart for explaining the frame transmission timing of the relay device. The arrows in Fig. 5 indicate sampling timing. The period Ta from the current sampling timing at time t0 to the next sampling timing at time t0x indicates the sampling period. For example, the sampling period is set to an electrical angle of 30° of the system frequency (for example, 1670 μs in the case of a 50 Hz system).

[0056] 5, the first to fourth relay devices transmit, at different timings, frames including electrical quantity data sampled at the same time to the switch 3. That is, the transmission periods of the frames F1 to F4 do not overlap with each other.

[0057] For example, the first relay device transmits frame F1 sampled at the sampling timing at time t0 when time T1 has elapsed from the sampling timing (i.e., time t1). The second relay device transmits frame F2 sampled at the sampling timing when time T2 has elapsed from the sampling timing (i.e., time t2). Note that frame F2 is transmitted after the transmission of frame F1 is completed. Therefore, the period during which the first relay device transmits frame F1 does not overlap with the period during which the second relay device transmits frame F2.

[0058] Similarly, the third relay transmits frame F3 sampled at the sampling timing when time T3 has elapsed since the sampling timing (i.e., time t3), and the fourth relay transmits frame F4 sampled at the sampling timing when time T4 has elapsed since the sampling timing (i.e., time t4).

[0059] 5, the switch 3 receives frames F1 to F4 from the first to fourth relay devices at different times. The switch 3 stores the received frames in an internal buffer and immediately transmits the frames to other switches 3.

[0060] Therefore, the timing at which the switch 3 transmits frames F1 to F4 to the other switches 3 is substantially synchronized with the timing (e.g., times t1 to t4) at which the first to fourth relay devices transmit frames F1 to F4 to the switch 3. For example, the switch 3 transmits frame F1 received from the first relay device to the other switch 3, and then receives frame F2 from the second relay device and transmits frame F2 to the other switch 3.

[0061] This reduces the number of frames (i.e., the amount of data) stored simultaneously in the buffer of the switch 3, compared to a transmission method in which the first to fourth relay devices simultaneously transmit frames F1 to F4 after a certain period from the sampling timing at time t0. This reduces the load on the buffer of each switch 3, and prevents data (i.e., frames) from overflowing from the buffer.

[0062] In the example of Fig. 5, frames F1 and F2 belong to group G1, and frames F3 and F4 belong to group G2. The time difference between the timing when the first relay device belonging to group G1 transmits frame F1 (i.e., time t1) and the timing when the second relay device belonging to group G1 transmits frame F2 (i.e., time t2) is "Ts". The time difference between the timing when the third relay device belonging to group G2 transmits frame F3 (i.e., time t3) and the timing when the fourth relay device belonging to group G2 transmits frame F4 (i.e., time t4) is "Ts".

[0063] On the other hand, the time difference between the transmission timing of frame F2 and the transmission timing of frame F3 is "Ts1." Time Ts1 is sufficiently longer than time Ts. That is, the interval between the frame transmission timings of relay devices 2 belonging to different groups (e.g., time Ts1) is sufficiently longer than the interval between the frame transmission timings of relay devices 2 belonging to the same group (e.g., time Ts).

[0064] The switch 3 sequentially transmits the received frames F1 to F4 to the other switches 3. Specifically, the switch 3 transmits frames F3 and F4 belonging to group G2 a relatively long time after transmitting frames F1 and F2 belonging to group G1. Therefore, the timing at which each frame F1 and F2 arrives at the switch 3 from the other switches 3 is significantly different from the timing at which each frame F3 and F4 arrives at the switch 3 from the other switches 3. As a result, the frames F1 and F2 corresponding to group G1 and the frames F3 and F4 corresponding to group G2 arrive at each switch 3 in a distributed manner, thereby reducing the number of frames received by each switch 3 in a short period of time.

[0065] Fig. 6 is a diagram for explaining the arrival timing of a frame at a switch according to the present embodiment. The horizontal axis of Fig. 6 indicates the relay number of each relay device 2. Specifically, the relay numbers of relay devices 2_1 to 2_20 are indicated by 1 to 20, respectively. The vertical axis of Fig. 6 indicates the arrival time from the sampling timing until the frame of each relay device 2 arrives at the first switch 3_1. For ease of explanation, it is assumed that the distance between each switch 3 shown in Fig. 1 is the same.

[0066] As shown in Fig. 6, frames of the relay devices 2_1 and 2_2 arrive at the first switch 3_1 in sequence at fixed time intervals (e.g., 10 μs, corresponding to time Ts in Fig. 5). Then, frames of the relay devices 2_5 and 2_6 connected to the second switch 3_2 adjacent to the first switch 3_1 arrive at the first switch 3_1 in sequence at 10 μs. Then, frames of the relay devices 2_9 and 2_10 connected to the third switch 3_3, frames of the relay devices 2_13 and 2_14 connected to the fourth switch 3_4, and frames of the relay devices 2_17 and 2_18 connected to the fifth switch 3_5 arrive at the first switch 3_1 in sequence.

[0067] Approximately 200 μs after the sampling timing, frames from the relay devices 2_3 and 2_4 connected to the first switch 3_1 arrive at the first switch 3_1 in sequence every 10 μs. Then, frames from the relay devices 2_7 and 2_8 connected to the second switch 3_2, frames from the relay devices 2_11 and 2_12 connected to the third switch 3_3, frames from the relay devices 2_15 and 2_16 connected to the fourth switch 3_4, and frames from the relay devices 2_19 and 2_20 connected to the fifth switch 3_5 arrive at the first switch 3_1 in sequence.

[0068] In this manner, in the frame transmission method according to the present embodiment, frames F1 and F2 corresponding to the first and second relay devices, respectively, arrive at the switch 3, and then frames F3 and F4 corresponding to the third and fourth relay devices, respectively, arrive at the first switch 3_1. As a result, each frame arrives at the first switch 3_1 in a distributed manner.

[0069] In the frame transmission method according to the present embodiment, the interval between the frame transmission timings of the first to fourth relay devices can be made constant. That is, in the transmission method shown in Fig. 5, the time Ts1 and the time Ts2 can be made the same length. However, as shown in Fig. 5, by dividing the frames F1 to F4 into two groups and providing a relatively long delay time between the transmission timing of the frames belonging to the first group and the transmission timing of the frames belonging to the second group, the arrival timing of each frame at the switch 3 can be further dispersed. Therefore, the number of frames received by each switch 3 in a short period of time is further reduced.

[0070] 5, following frames F3 and F4 corresponding to group G2, frames FX and FY arrive in sequence at the switch 3. Frame FX belongs to group G3, and frame FY belongs to group G4.

[0071] The monitoring device 5 transmits a frame FX to each switch 3 at a timing when a time T5 has elapsed from the sampling timing (for example, at time t5). The frame FX includes data obtained by dividing the monitoring data. The monitoring data includes, for example, at least one of the electric quantity data of the first to fourth power transmission lines and the calculation data based on the electric quantity data. The monitoring device 5 transmits all the necessary monitoring data by transmitting a frame FX every time time t5 after the sampling timing arrives.

[0072] The relay device 2, which has received a request from the analysis device 60, transmits a frame FY at a timing when a time T6 has elapsed from the sampling timing (for example, at time t6). The frame FY includes data obtained by dividing offline data (data for accident analysis). The offline data is, for example, electrical quantity data and calculation data related to the power transmission line for a certain period before and after the occurrence of an accident. The relay device 2, which has received a request from the analysis device 60, transmits all offline data required for accident analysis by transmitting a frame FY every time time t6 after the sampling timing arrives.

[0073] The switch 3 sequentially transmits the received frames F1-F4, FX, and FY to the other switches. Therefore, the timing at which the switch 3 transmits the frames F1-F4, FX, and FY to the other switches 3 is substantially synchronized with the timing at which each relay device 2 transmits the frames F1-F4, FX, and FY to the switch 3 (for example, times t1-t6).

[0074] 5, the interval between frame transmission timings of relay devices 2 belonging to different groups (e.g., time Ts1) is sufficiently longer than the interval between frame transmission timings of relay devices 2 belonging to the same group (e.g., time Ts). This allows the arrival timings of the frames at the switch 3 to be dispersed.

[0075] In this manner, in the frame transmission method according to the present embodiment, in a sampling period, each relay device 2 transmits divided data of monitoring data and offline data while transmitting electrical quantity data measured at the latest sampling timing.

[0076] Here, the electric quantity data is used in the current differential calculation executed by each relay device 2 at each sampling period, and therefore is data that needs to be transmitted at a high cycle (hereinafter also referred to as "high-speed cycle data"). On the other hand, the monitoring data and offline data can be transmitted at a low cycle compared to the electric quantity data, and the amount of data is larger than that of the electric quantity data. In particular, the offline data is data that is transmitted irregularly when an accident occurs in a protection section (for example, any of the first to fourth transmission lines), and is data that is larger in amount than the monitoring data. Although the electric quantity data, the monitoring data, and the offline data have different transmission cycles and data amounts, data other than the high-speed cycle data (for example, the monitoring data and the offline data) can be transmitted and received using the same network NW by managing the transmission timing and division number of each data. By making maximum use of the network NW in this way, there is no need to build a new network for other data, and therefore the total cost of the protection relay system 1000 can be reduced.

[0077] On the other hand, however, in addition to the frames F1-F4, FX transmitted by each relay device 2 and the monitoring device 5, a plurality of frames FY transmitted by a plurality of relay devices 2 requested by the analysis device 60 arrive sequentially at the fifth switch 3_5 to which the analysis device 60 is connected. When the arrival timings of the plurality of frames FY are concentrated in a short period of time, congestion of the plurality of frames FY occurs as shown in FIG.

[0078] Fig. 7 is a diagram for explaining the arrival timing of a frame at the fifth switch 3_5. The arrows in Fig. 7 indicate sampling timing. The period Ta from the current sampling timing at time t0 to the next sampling timing at time t0x indicates the sampling period.

[0079] Frames from each of the relay devices 2_1 to 2_20 arrive at the fifth switch 3_5 in sequence. In Fig. 7, a reception period TG1 indicates a period during which frames F1 and F2 belonging to group G1 of each relay device 2 arrive. That is, during the reception period TG1, frames from the first relay devices 2_1, 2_5, 2_9, 2_13, and 2_17 and the second relay devices 2_2, 2_6, 2_10, 2_14, and 2_18 arrive at the fifth switch 3_5 in sequence.

[0080] The reception period TG2 indicates a period during which frames F3 and F4 belonging to group G2 of each relay device 2 arrive. That is, during the reception period TG2, frames of the third relay devices 2_3, 2_7, 2_11, 2_15, and 2_19 and the fourth relay devices 2_4, 2_8, 2_12, 2_16, and 2_20 arrive at the fifth switch 3_5 in sequence. In this manner, the reception periods TG1 and TG2 correspond to reception periods of high-speed cycle data (i.e., electrical quantity data measured at the latest sampling timing).

[0081] The reception period TG3 indicates a period during which frames FX belonging to the group G3 arrive from each monitoring device 5. That is, during the reception period TG3, the frames FX from the monitoring devices 5_1 to 5_5 arrive sequentially at the fifth switch 3_5.

[0082] The reception period TG4 indicates a period during which the frame FY belonging to the group G4 of the relay devices 2 requested by the analysis device 60 arrives. For example, assume that the analysis device 60 requests the four first relay devices 2_1, 2_5, 2_9, and 2_13 to transmit offline data in response to the occurrence of an accident on the first power transmission line. In this case, the first relay devices 2_1, 2_5, 2_9, and 2_13 transmit the frame FY to the switches 3_1, 3_2, 3_3, and 3_4, respectively, at a timing when a time T6 has elapsed from the sampling timing at the time t0. Each of the switches 3_1, 3_2, 3_3, and 3_4 transmits the received frame FY to the fifth switch 3_5.

[0083] At this time, if the arrival timings of the four frames FY at the fifth switch 3_5 are concentrated in a short period of time, as shown in FIG. 7, congestion of the frames FY occurs at the fifth switch 3_5. The congestion of the frames FY places a heavy load on the buffer of the fifth switch 3_5. Then, as shown in FIG. 7, a waiting state of data that exceeds the memory capacity of the buffer occurs, and as a result, the reception timing of at least one frame FY may be shifted to the next sampling timing at time t0x. In this case, there is a possibility that the reception period TG4 of the frame FY overlaps with the reception period TG1 of the frames F1 and F2 belonging to the group G1 of each relay device 2, which are transmitted after the sampling timing at time t0x.

[0084] When the reception period TG4 of the frame FY and the reception period TG1 of the frames F1 and F2 overlap, a standby state of the frames F1 and F2 occurs in the fifth switch 3_5, which may delay the reception timing of the fast cycle data. If the reception timing of the electrical quantity data, which is fast cycle data, is delayed, each relay device 2 cannot normally perform the current differential calculation, and therefore temporarily locks the protection function calculation. The protection relay system 1000 cannot tolerate such a situation, so it is necessary to prevent the congestion of the frame FY from occurring in the fifth switch 3_5.

[0085] Therefore, in this embodiment, the protection relay system 1000 is provided with a management device 80 for managing the frame transmission timing in each relay device 2. The management device 80 is configured to manage the timing of transmitting a frame FY including offline data from each relay device 2 to the switch 3, as requested by the analysis device 60. In the following, the functional configuration of the management device 80 will be described assuming a case where the analysis device 60 requests the first relay devices 2_1, 2_5 to transmit offline data (see FIG. 8).

[0086] <Offline data transmission process> Fig. 8 is a diagram showing how offline data is transmitted to the analysis device 60. As shown in Fig. 8, when the analysis device 60 requests the first relay device 2_1 to transmit offline data, frames F1-F4 of the relay devices 2_1-2_4 and a frame FY including the offline data of the first relay device 2_1 arrive sequentially at the first switch 3_1. The first switch 3_1 transmits the received frames F1-F4 to another switch 3 and transmits the received frame FY to the fifth switch 3_5. The frame FY that arrives at the fifth switch 3_5 is provided to the analysis device 60.

[0087] Furthermore, when the analysis device 60 requests the first relay device 2_5 to transmit offline data, the frames F1-F4 of the relay devices 2_5-2_8 and the frame FY including the offline data of the first relay device 2_5 arrive sequentially at the second switch 3_2. The second switch 3_2 transmits the received frames F1-F4 to the other switches 3 and transmits the received frame FY to the fifth switch 3_5. The frame FY arriving at the fifth switch 3_5 is provided to the analysis device 60.

[0088] In order to prevent congestion of the two frames FY from occurring at the fifth switch 3_5, the management device 80 manages the timing at which the first relay device 2_1 transmits a frame FY to the first switch 3_1 and the timing at which the first relay device 2_5 transmits a frame FY to the second switch 3_2, based on frame reception information collected from each switch 3.

[0089] 9 is a sequence diagram illustrating the transmission process of offline data in the protection relay system 1000. The transmission process of offline data is executed in parallel with the transmission process of high-speed periodic data and monitoring data.

[0090] 9, in process P31, each relay device 2 transmits frames F1-F4 including electrical quantity data sampled at the sampling timing to each switch 3. Each monitoring device 5 (not shown) also transmits a frame FX including monitoring data to each switch 3.

[0091] Each switch 3 sequentially transmits the received frames to the other switches 3. Each switch 3 acquires frame reception information for each received frame through process P21 and stores the acquired frame reception information in its internal memory. In process P21, each switch 3 acquires, as frame reception information for all received frames, information regarding the device that transmitted the frame (i.e., the source device), the device that received the frame (i.e., the destination device), the timing at which the frame arrived at the switch 3 (i.e., the timing at which the switch 3 received the frame), and the amount of data in the frame.

[0092] (Storage process of frame reception information for each switch: P21 in Figure 9) Fig. 10 is a diagram for explaining the storage process (P21 in Fig. 9) of frame reception information in each switch 3. In the upper part of Fig. 10, the frame reception timing in each switch 3 is illustrated.

[0093] Each switch 3 has a counter for measuring the timing of receiving a frame. The counter updates the counter value in synchronization with a synchronization clock for synchronizing the time of the synchronizer 20 with the time of each relay device 2, for example. The counter starts counting from "0" and is configured to add 1 to the counter value every time 1 μs has elapsed. The counter value is reset to "0" when it reaches "1,000,000" (i.e., when 1,000,000 μs (=1 s) has elapsed).

[0094] The horizontal axis in FIG. 10 indicates the counter value of the counter of switch 3. The black arrows in the figure indicate the sampling timing. It is assumed that the counter value "0" of the counter coincides with the sampling timing. It is also assumed that the sampling period is set to 1.67 ms (=1670 μs). Therefore, the counter value at the first sampling timing is "0", and the counter value at the second sampling timing is "1666".

[0095] The lower part of Fig. 10 shows the frame reception timing during a first sampling period Ta1 from the first sampling timing to the second sampling timing. The first sampling period Ta1 corresponds to the first sampling period after the counter starts counting.

[0096] In the first sampling period Ta1, the switch 3 sequentially receives frames from each of the relay devices 2_1 to 2_20. Reception periods TG1 and TG2 indicate periods during which the switch 3 receives frames F1 to F4 from each of the relay devices 2_1 to 2_20. The white arrows in the figure indicate the timings at which the switch 3 receives frames from each of the relay devices 2_1 to 2_20 in the reception periods TG1 and TG2.

[0097] The switch 3 acquires the counter value of the reception timing of each frame in the first sampling period Ta1 and stores the acquired counter value in an internal memory. Each counter value indicates the arrival time of each frame from the first sampling period until it arrives at the switch 3, and represents the reception timing of each frame in the first sampling period Ta1.

[0098] Here, since frames F1 to F4 are received in each sampling period after the second sampling period Ta2, the counter values ​​of the reception timing of frames F1 to F4 are acquired for each sampling period. However, switch 3 is configured to store the counter value of the first reception timing after the counter starts counting from "0". Therefore, for frames whose counter values ​​have already been stored, the stored counter value is not overwritten, and the counter value is held until the internal memory is reset. As a result, for frames F1 to F4, the count values ​​of the reception timing in the first sampling period Ta1 continue to be held.

[0099] On the other hand, frames FX and FY of monitoring data or offline data may not be received in the first sampling period Ta1, but may be received in the second sampling period Ta2 or later. In the example of Fig. 10, frame FX including monitoring data is received in the third sampling period Ta3 (corresponding to reception period TG3). In this case, switch 3 stores in its internal memory the counter value (e.g., "4332") of the reception timing of frame FX acquired in the third sampling period Ta3.

[0100] 9, in process P11, the management device 80 collects frame reception information from each switch 3. In process P22, upon receiving a request from the management device 80, each switch 3 transmits the frame reception information stored in its internal memory to the management device 80.

[0101] (Frame reception information collection process: P11 in Figure 9) Fig. 11 is a sequence diagram for explaining the process of collecting frame reception information (P11 in Fig. 9) in the management device 80. Fig. 11 shows the flow of exchange of frame reception information between the management device 80 and the first switch 3_1 and the second switch 3_2.

[0102] 11, in process P51, each switch 3 updates the counter value of the counter whose counter value is "0" in synchronization with the synchronous clock. The counter starts counting from "0" and adds 1 to the counter value every time 1 μs has elapsed.

[0103] In process P52, each switch 3 acquires the reception timing of a frame received in each sampling period based on the counter value of the counter. As described above, each switch 3 acquires the counter value of the first reception timing for each frame after the counter starts counting from "0". Then, each switch 3 generates frame reception information for each frame including the acquired reception timing and information on the source device and destination device, and stores the information in the internal memory.

[0104] The management device 80 collects frame reception information of each switch 3 in order, starting from the first switch 3_1. Specifically, the management device 80 first requests the first switch 3_1 to transmit the frame reception information in a process P41. In a process P53, the first switch 3_1 reads the frame reception information from its internal memory in response to the request from the management device 80, and transmits the frame reception information to the management device 80 via the communication path R. Note that in each switch 3, the transmission timing of the frame reception information is set to be later than the frame reception period in the sampling period so that the frame reception information received from the first switch 3_1 does not collide with the frames received from each relay device 2.

[0105] Upon receiving the frame reception information from the first switch 3_1, the management device 80 requests the first switch 3_1 to reset the internal memory in a process P42.

[0106] In process P54, the first switch 3_1 resets the internal memory in accordance with the request from the management device 80. This resets the frame reception information of the first switch 3_1 stored in the internal memory. Note that the first switch 3_1 may be configured to reset the internal memory at the timing when the counter value is reset to "0" (process P55).

[0107] When the frame reception information of the first switch 3_1 is acquired, the management device 80 subsequently requests the second switch 3_2 to transmit the frame reception information in process P43. In process P53, the second switch 3_1 reads the frame reception information from its internal memory in response to the request of the management device 80, and transmits the frame reception information to the management device 80 via the communication path R. In the second switch 3_2 as well, the transmission timing of the frame reception information is set to be later than the frame reception period in the sampling period so that the frame reception information received from the second switch 3_2 does not collide with the frames received from each relay device 2 in each switch 3.

[0108] Upon receiving the frame reception information from the second switch 3_2, the management device 80 requests the second switch 3_2 to reset its internal memory in process P44. The second switch 3_2 resets its internal memory in accordance with the request from the management device 80 in process P54. This resets the frame reception information of the second switch 3_2 stored in the internal memory. The second switch 3_2 may be configured to reset its internal memory at the same time that it resets the counter value to "0" (process P55).

[0109] The management device 80 sequentially requests the third to fifth switches 3 to transmit frame reception information as well. Then, the management device 80 requests the switch 3 that has received the frame reception information to reset its internal memory.

[0110] 9, when the management device 80 collects frame reception information of each switch 3 in process P11, it creates a table summarizing the reception status of each switch 3 based on the collected frame reception information. This table records the frame reception timing during the first sampling period Ta1 of each switch 3. The management device 80 saves the created table in its internal memory.

[0111] For a frame that is not received in the first sampling period Ta1 but is received in the second sampling period Ta2 or later, the management device 80 converts the reception timing of the frame into the reception timing of the first sampling period Ta1, assuming that the frame was received in the first sampling period Ta1. For example, as shown in FIG. 10, if the counter value of the reception timing of a frame FX that is first received in the third sampling period Ta3 is "4332", the management device 80 sets the remainder "1000" obtained by dividing the counter value "4332" by the counter value per sampling period "1666" as the reception timing of the frame FX. In this way, the reception timing of high-speed cycle data and the reception timing of data other than high-speed cycle data (for example, monitoring data and offline data) can be managed together within one sampling period.

[0112] The management device 80 repeatedly executes the process of P11 at a predetermined cycle. The cycle for executing the process P11 can be set, for example, so as to secure the time (for example, 10 seconds) required for the management device 80 to create the above table. Each time the process P11 is executed, the above table is created using the latest frame reception information of each switch 3.

[0113] When an accident occurs in a protection section (for example, any one of the first to fourth power transmission lines), the analysis device 60 receives a notification that the accident has occurred from at least one of the relay devices 2_1 to 2_20. Upon receiving the notification of the accident occurrence, the analysis device 60 requests at least one relay device 2 to transmit data related to the accident (offline data) in process P01. However, the analysis device 60 transmits the request to transmit the offline data to the management device 80, not to the at least one relay device 2.

[0114] When the management device 80 receives a transmission request for offline data from the analysis device 60 in process P12, it calculates in process P13 a transmission condition for the requested relay device 2 to transmit a frame FY including offline data to the switch 3. In process P13, the management device 80 calculates a delay time from the sampling timing to the timing at which the requested relay device 2 transmits the frame FY (hereinafter also referred to as a "transmission delay time") based on the frame reception information of each switch 3 collected in process P11. The management device 80 further calculates the number of times (hereinafter also referred to as the "number of transmitted data") that the requested relay device 2 continuously transmits a predetermined unit data amount of offline data within one sampling period.

[0115] (Calculation process of transmission delay time and transmission data amount: P13 in Figure 9) FIG. 12 is a diagram for explaining the transmission delay time of the frame FY at the requested relay device 2. In FIG. 12(A)-(E), the arrival timings of the frames at the first to fifth switches are shown aligned. In FIG. 12(F), the arrival timings of the frames at the first to fifth switches are shown overlapping each other. The horizontal axis of each diagram indicates the relay number of each relay device 2. The vertical axis of each diagram indicates the arrival time (unit: μs) from the sampling timing until the frame of each relay device 2 arrives at the switch 3. The vertical axis indicates the sampling period (1667 μs) from the current sampling timing to the next sampling timing.

[0116] FIG. 12(A) shows the frame arrival timing at the first switch 3_1. The black dots in the figure represent the frame arrival timing of each of the relay devices 2_1 to 2_20. The frames of each of the relay devices 2_1 and 2_2 arrive at the first switch 3_1 in sequence every 10 μs. Then, the frames of each of the relay devices 2_5 and 2_6 and the frames of each of the relay devices 2_9 and 2_10 arrive at the first switch 3_1 in sequence. After about 200 μs from the sampling timing, the frames of each of the relay devices 2_3 and 2_4 arrive at the first switch 3_1 in sequence. Subsequently, frames from the relay devices 2_7 and 2_8, 2_13 and 2_14, 2_11 and 2_12, 2_17 and 2_18, 2_15 and 2_16, and 2_19 and 2_20 arrive at the first switch 3_1 in sequence.

[0117] FIG. 12(B) shows the frame arrival timing at the second switch 3_2. The black squares in the figure represent the frame arrival timing at each of the relay devices 2_1-2_20. FIG. 12(C) shows the frame arrival timing at the third switch 3_3. The white circles in the figure represent the frame arrival timing at each of the relay devices 2_1-2_20. FIG. 12(D) shows the frame arrival timing at the fourth switch 3_4. The white triangles in the figure represent the frame arrival timing at each of the relay devices 2_1-2_20. FIG. 12(E) shows the frame arrival timing at the fifth switch 3_5. The white squares in the figure represent the frame arrival timing at each of the relay devices 2_1-2_20.

[0118] In this manner, the frames of the relay devices 2_1 to 2_20 arrive sequentially at each switch 3. As shown in Fig. 12(F), the reception period of the frames F1 to F4 of the relay devices 2_1 to 2_20 at each switch 3 is 600 to 700 µs.

[0119] Here, it is assumed that a frame FY including offline data is transmitted from the first relay device 2_1 to the analysis device 60. In Fig. 12(A) to (E), a star symbol represents the arrival timing of the frame FY of the first relay device 3_1 at each switch 3. In Fig. 12(A), as an example, it is assumed that the first relay device 3_1 transmits the frame FY to the first switch 3_1 at a time when 800 μs has elapsed from the sampling timing. The first switch 3_1 transmits the received frame FY to the second switch 3_2.

[0120] The frame FY arrives at the second switch 3_2 adjacent to the first switch 3_1 at around 820 μs. The frame FY arrives at the third switch 3_3 adjacent to the second switch 3_2 at around 940 μs. The frame FY of the first relay device 3_1 arrives at the fourth switch 3_4 adjacent to the third switch 3_3 at around 960 μs. The frame FY of the first relay device 2_1 arrives at the fifth switch 3_5 adjacent to the fourth switch 3_4 at around 1250 μs.

[0121] At any switch 3, the frame FY of the first relay device 2_1 arrives at a time later than 600 to 700 μs, which is the reception time of the frames F1 to F4 of the relay devices 2_1 to 2_20. This shows that by making the transmission delay time of the frame FY at the first relay device 2_1 longer than the reception period of the frames F1 to F4 of the relay devices 2_1 to 2_20 at each switch 3, the arrival timing of the frames F1 to F4 of the relay devices 2_1 to 2_20 and the arrival timing of the frame FY of the first relay device 2_1 do not overlap at each switch 3.

[0122] 12 as frame reception information of each switch 3. The management device 80 also recognizes in advance that the analysis device 60 is connected to the fifth switch 3_5. Based on the frame reception information of each switch 3, the management device 80 calculates the transmission delay time of the frame FY of the requested relay device 2 according to the procedure shown below so as to prevent congestion of the frame FY at the fifth switch 3_5.

[0123] First, the management device 80 calculates the maximum reception time of a frame at the fifth switch 3_5. The maximum reception time of a frame is the maximum value of the arrival time of the frame at the switch 3 (the time from the sampling timing until the frame arrives at the switch 3). In the example of FIG. 12(E), the frame of the fourth relay device 2_4 is the frame that arrives latest at the fifth switch 3_5, and its arrival time is 700 μs, so that the maximum reception time is 700 μs. Therefore, if the transmission delay time of the frame FY of the first relay device 2_1 is set so that the arrival timing of the frame FY at the fifth switch 3_5 is later than the maximum reception time 700 μs, it is possible to prevent the arrival timing of the frames F1-F4 of the relay devices 2_1-2_20 from overlapping with the arrival timing of the frame FY at the fifth switch 3_5.

[0124] Next, the management device 80 calculates a delay time from the timing when the frame of the fourth relay device 2_4 arrives at the first switch 3_1 to the timing when the frame arrives at the fifth switch 3_5. This delay time corresponds to the time (transmission time) required for the frame transmitted from the first switch 3_1 to arrive at the fifth switch 3_5 via the communication path R.

[0125] Specifically, the management device 80 calculates the delay time by determining the difference between the arrival timing of the frame of the fourth relay device 2_4 at the first switch 3_1 and the arrival timing of the frame of the fourth relay device 2_4 at the fifth switch 3_5. In the example of Fig. 12, the arrival timing of the frame of the fourth relay device 2_4 at the first switch 3_1 is 210 μs, and the arrival timing of the frame of the fourth relay device 2_4 at the fifth switch 3_5 is 700 μs, so the delay time is 700 μs-210 μs=490 μs.

[0126] Next, the management device 80 calculates the transmission delay time and the number of pieces of transmission data of the frame FY in the first relay device 3_1 by using the calculated maximum reception time and delay time. Fig. 13 is a diagram for explaining a method of calculating the transmission delay time and the number of pieces of transmission data.

[0127] FIG. 13 shows a sampling period (1667 μs), a maximum reception time (700 μs) at the fifth switch 3_5, and a delay time (490 μs) between the first switch 3_1 and the fifth switch 3_5.

[0128] In order for the frame FY of the first relay device 2_1 to arrive at the fifth switch 3_5 within the sampling period (1667 μs), the first relay device 2_1 needs to transmit the frame FY to the first switch 3_1 within the time (1667 μs-490 μs=1187 μs) obtained by subtracting the delay time (490 μs) from the sampling period (1667 μs). In other words, the timing 1187 μs after the sampling timing is the final timing at which the first relay device 2_1 transmits the frame FY to the first switch 3_1.

[0129] However, during the maximum reception time (700 μs), the fifth switch 3_5 receives the frames F1-F4 from the relay devices 2_1-2_20. Therefore, the range of the transmission delay time that allows the frame FY to arrive at the fifth switch 3_5 within the sampling period without overlapping with the frames F1-F4 is greater than 700 μs and less than 1187 μs (700 μs<transmission delay time<1187 μs).

[0130] On the other hand, in order to secure the amount of offline data to be transmitted to the fifth switch 3_5 within one sampling period, it is required to make the time for the first relay device 2_1 to transmit the frame FY as long as possible. Therefore, in Fig. 13, the transmission delay time is set to "750 μs" by adding a predetermined time of 50 μs to the maximum reception time of 700 μs. In other words, the first relay device 2_1 transmits the frame FY to the first switch 3_1 at the timing when 750 μs has elapsed from the sampling timing.

[0131] Next, the management device 80 calculates the time during which offline data can be transmitted within one sampling period (hereinafter also referred to as "transmittable data time") from the transmission delay time of 750 μs. The transmittable data time is 437 μs, which is the time obtained by subtracting the transmission delay time of 750 μs from the upper limit value of the setting range of the transmission delay time of 1187 μs (1187 μs - 750 μs = 437 μs).

[0132] Next, the management device 80 calculates the number of times (number of transmission data) that offline data of a predetermined unit data amount will be continuously transmitted within the transmittable data time of 437 μs. Here, the data amount of one transmission packet is 1000 bytes. When the communication speed is 1 Gbps, the amount of transmission data per time is 1000 bytes x 8 bits = 8000 bits, and one data transmission takes about 10 μs. The time obtained by multiplying this 10 μs by the number of transmission data becomes the transmission data time used to transmit the offline data.

[0133] Here, the margin of the transmission data time in the transmittable data time can be set in advance by the user of the protection relay system. In the protection relay system according to this embodiment, since the top priority is to ensure the protection function of each relay device 2, it is important that the arrival timing of the frame FY at the fifth switch 3_5 does not overlap with the arrival timing of the frames F1 to F4 at the relay devices 2_1 to 2_20. Therefore, in this embodiment, a threshold is set for the ratio of the transmission data time to the transmittable data time, and the transmission data time is limited to a range not exceeding the threshold. For example, the threshold for the ratio of the transmission data time to the transmittable data time is set to 30%. Therefore, when the transmittable data time is 437 μs, the transmission data time is 437 μs×30%=131 μs.

[0134] Assuming that one data transmission takes 10 μs as described above, the number of times that offline data of a unit data amount can be transmitted consecutively in one sampling period (number of times transmission is possible) is 131 μs / 10 μs=13 times. Note that an upper limit (for example, 10 times) can also be set for the number of data transmissions. In this case, the number of data transmissions is set to "10 times."

[0135] If the number of transmission data is 10, the amount of offline data transmitted in one sampling period is 1000 bytes (unit data amount) × 10 times (number of transmission data) = 10 kbytes. Therefore, if the amount of offline data is 500 kbytes, the first relay device 2_1 can complete the transmission of the offline data by dividing it into 50 sampling periods and transmitting the offline data.

[0136] 12 and 13, the method of calculating the transmission delay time and the number of transmission data of the frame FY in the first relay device 2_1 has been described, but the transmission delay time and the number of transmission data of the frame FY in the first relay device 2_5 can also be calculated using the same method. However, in the case of the first relay device 2_5, the calculation method of the delay time shown in FIG. 13 is different from that of the first relay device 2_1. The delay time in the case of the first relay device 2_5 is the delay time from the timing when the frame of the fourth relay device 2_4 arrives at the second switch 3_2 to the timing when the frame arrives at the fifth switch 3_5. This delay time corresponds to the time it takes for the frame transmitted from the second switch 3_2 to arrive at the fifth switch 3_5 via the communication path R.

[0137] 9, when the management device 80 calculates in process P13 the transmission conditions (transmission delay time and number of pieces of transmission data) for transmitting the frame FY contained in the requested relay device 2, the management device 80 proceeds to process P14 and requests the relay device 2 to transmit offline data. In process P14, the management device 80 transmits a transmission request including the transmission conditions (transmission delay time and number of pieces of transmission data) calculated in process P13 to the relay device 2.

[0138] When the relay device 2 receives a transmission request for offline data from the management device 80 in process P32, the relay device 2 proceeds to process P33 and transmits the offline data according to the transmission conditions included in the transmission request. In process P33, the relay device 2 starts transmitting the offline data at a time when a transmission delay time (e.g., 750 μs) has elapsed from the sampling timing for each sampling period. The relay device 2 divides the offline data into data of a predetermined unit data amount (e.g., 1000 bytes) and transmits this divided data to the analysis device 60 consecutively for each sampling period by the number of transmission data (e.g., 10 times). The relay device 2 repeatedly executes this transmission operation for each sampling period until transmission of all divided data is completed.

[0139] In step P02, the analysis device 60 receives the divided data for the number of transmission data for each sampling period. When all the divided data have been received, in step P03, the analysis device 60 reports to the relay device 2 that reception of the offline data has been completed.

[0140] When the relay device 2 receives the report of completion of reception from the analysis device 60, it reports to the management device 80 in process P34 that the transmission of the offline data has been completed.

[0141] When the management device 80 receives the report from the relay device 2 in process P15, it confirms that the transmission of the offline data of the relay device 2 has been completed. If there are multiple relay devices 2 to which the transmission of offline data has been requested, the management device 80 executes processes P13 and P14 for the next relay device 2, and requests that relay device 2 to transmit the offline data.

[0142] <Processing flow> Next, a description will be given of the processing flows of the analysis device 60, the management device 80, and the relay device 2 in the above-mentioned offline data transmission processing. In the following, the processing flows of each device will be described assuming a case where the analysis device 60 requests the first relay devices 2_1 and 2_5 to transmit offline data (see FIG. 8).

[0143] (Processing flow of the analysis device 60) Fig. 14 is a flowchart showing a process flow in the analysis device 60. As shown in Fig. 14, in step (hereinafter simply denoted as "S") 01, the analysis device 60 transmits a transmission request for offline data to the first relay devices 2_1, 2_5 to the management device 80. The management device 80, which has received the transmission request, calculates transmission conditions (transmission delay time and the number of transmission data items) for offline data in each relay device 2 based on frame reception information of each switch 3, and transmits a transmission request including the calculated transmission conditions to the first relay devices 2_1, 2_5 (see Fig. 15).

[0144] The analysis device 60 determines whether or not the first relay device 2_1 has received a notification that the first relay device 2_1 cannot transmit the offline data in S02. As will be described later, whether or not the first relay device 2_1 can transmit the offline data is determined by the management device 80.

[0145] When receiving a notification that transmission of the offline data is not possible in the first relay device 2_1 (YES in S02), the analysis device 60 ends the process of requesting the offline data to the first relay device 2_1.

[0146] When the analysis device 60 has not received a notification that the offline data cannot be transmitted from the first relay device 2_1 (NO in S02), the analysis device 60 receives the offline data from the first relay device 2_1 in S03. As described above, the offline data is transmitted over a plurality of sampling periods in accordance with the transmission conditions. In response to receiving all the offline data, the analysis device 60 reports to the first relay device 2_1 in S04 that the reception of the offline data has been completed, and ends the process of requesting the offline data from the first relay device 2_1.

[0147] Next, the analysis device 60 judges whether or not the first relay device 2_5 has received a notice that the offline data cannot be transmitted in S05. When the analysis device 60 has received a notice that the offline data cannot be transmitted in the first relay device 2_5 (YES in S05), the analysis device 60 ends the process of requesting the offline data from the first relay device 2_5.

[0148] When the notification of the inability to transmit the offline data has not been received from the first relay device 2_5 (NO in S05), the analysis device 60 receives the offline data from the first relay device 2_5 in S06. In response to receiving all the offline data, the analysis device 60 reports to the first relay device 2_5 that the reception of the offline data has been completed in S07, and ends the process of requesting the offline data from the first relay device 2_5.

[0149] Next, in S08, the analysis device 60 receives from the management device 80 a report that the offline data transmission process has been completed in all of the requested relay devices 2. When the number of requested relay devices 2 is two, the analysis device 60 receives a notification of the completion of the transmission process in response to the completion of the offline data transmission process in the first relay device 2_5. Upon receiving the notification, the analysis device 60 ends the offline data request process.

[0150] (Processing flow of management device 80) Fig. 15 is a flowchart showing a flow of processing in the management device 80. As shown in Fig. 15, the management device 80 receives a transmission request for offline data to the first relay devices 2_1 and 2_5 from the analysis device 60 in S11.

[0151] The management device 80 calculates the total number X of relay devices 2 that are the request destinations of offline data from the received transmission request in S12. When the request destinations are the first relay devices 2_1 and 2_5, X=2. In the subsequent processing, the management device 80 assigns serial numbers from 1 to X to the total number X of relay devices 2. For example, the device number of the first relay device 2_1 is set to 1, and the device number of the second relay device 2_5 is set to 2. Then, the management device 80 causes the relay devices 2 to execute the transmission processing of offline data in order from the relay device 2 with the lowest device number. Specifically, the management device 80 sets the initial value of the device number Y of the relay device 2 to be the target of the transmission processing to "1" (Y=1). As a result, the relay device 2 with the device number 1 (i.e., the first relay device 2_1) becomes the target of the transmission processing.

[0152] The management device 80 first calculates in S13 the transmission conditions for the frame FY including offline data for the relay device 2 with device number Y. In S13, the management device 80 calculates, based on the frame reception information of each switch 3 collected in advance, a "transmission delay time" that is the delay time from the sampling timing to the timing at which the relay device 2 transmits the frame FY, and a "number of transmission data" that is the number of times that the relay device 2 continuously transmits a unit data amount of offline data within one sampling period.

[0153] Next, the management device 80 determines in S14 whether the relay device 2 with device number Y is capable of transmitting offline data according to the calculated transmission conditions. For example, if the transmittable data time in the sampling period is short and the transmission data time cannot be secured, the determination in S14 is NO.

[0154] If it is determined that the relay device 2 with device number Y cannot transmit the offline data (NO in S14), the management device 80 proceeds to S18 and transmits a notification to the analysis device 60 that the relay device 2 corresponding to device number Y cannot transmit the offline data. In response to receiving the notification that transmission of offline data is not possible, the analysis device 60 ends the process of requesting offline data from the relay device 2 corresponding to device number Y (S02, S05 in FIG. 14).

[0155] If it is determined that the relay device 2 with device number Y can transmit offline data (YES in S14), the management device 80 proceeds to S15 and transmits a transmission request for the offline data to the relay device 2. This transmission request includes the transmission conditions (transmission delay time and the number of pieces of transmission data) calculated in S13. The relay device 2 that has received the transmission request executes a transmission process for the offline data in accordance with the transmission conditions.

[0156] During the execution of the offline data transmission process by the relay device 2, the management device 80 determines in S16 based on the notification from the relay device 2 whether or not a failure in the offline data transmission has been detected in the relay device 2. If a failure in the offline data transmission has been detected (YES determination in S16), the management device 80 transmits in S18 to the analysis device 60 a notification that the relay device 2 corresponding to device number Y is unable to transmit offline data. In response to receiving the notification, the analysis device 60 ends the offline data request process for the relay device 2 corresponding to device number Y.

[0157] If no failure in transmission of the offline data is detected (NO judgment in S16), the management device 80 confirms completion of transmission of the offline data from the relay device 2 with device number Y in S17 by receiving a report of completion of transmission of the offline data from the relay device 2.

[0158] Next, in S19, the management device 80 determines whether the device number Y matches the total number X of the requested relay devices 2. If Y=X (YES in S19), the management device 80 determines in S21 that the offline data transmission process has been completed in all of the requested relay devices 2, and reports the completion of the offline data transmission to the analysis device 60.

[0159] If Y=X is not true (NO in S19), the management device 80 proceeds to S20 and adds 1 to the device number Y, thereby making the relay device 2 whose device number is 1 greater than the relay device 2 that has completed the transmission process the target of the transmission process. That is, when the transmission process of the relay device 2 with device number 1 (i.e., the first relay device 2_1) is completed, Y=2, and the relay device 2 with device number 2 (i.e., the first relay device 2_5) becomes the target of the transmission process.

[0160] The management device 80 executes the process of S13 to S18 again for the new transmission process target. The process of S13 to S18 is repeatedly executed until Y=X is satisfied in S19. In this manner, the offline data transmission process is executed by all requested relay devices 2.

[0161] (Processing flow of relay device 2) Fig. 16 is a flowchart showing the flow of processing in the relay device 2 with device number Y in Fig. 15. As shown in Fig. 16, in S31, the relay device 2 with device number Y receives a transmission request for offline data from the management device 80. The transmission request includes transmission conditions for the offline data (transmission delay time and the number of pieces of transmission data).

[0162] The relay device 2 divides the offline data into unit data having a predetermined unit data amount by S32. The unit data amount corresponds to the data amount of one transmission packet (e.g., 1000 bytes). For example, if the amount of offline data is 500 kbytes, the offline data is divided into 500 unit data.

[0163] Next, in S33, the relay device 2 sets a transmission delay timing of offline data in one sampling period based on the transmission delay time specified by the management device 80. This transmission delay timing corresponds to the timing when the transmission delay time has elapsed from the sampling timing. The relay device 2 also sets the number of times to continuously transmit the above unit data in one sampling period based on the number of pieces of transmission data specified by the management device 80. The relay device 2 further sets a destination of the multiple unit data to be transmitted continuously. The destination of the offline data is the analysis device 60.

[0164] In S34, the relay device 2 transmits the offline data to the analysis device 60 according to the contents set in S33. In S34, the relay device 2 transmits the unit data consecutively for the transmission number of times for each sampling period from the transmission delay timing. The relay device 2 repeats the transmission process for each sampling period until all the unit data have been transmitted.

[0165] The relay device 2 judges whether or not the analysis device 60 has reported completion of reception of the offline data within a predetermined timeout period after executing the process of S34. If the analysis device 60 has reported completion of reception (YES in S35), the relay device 2 reports completion of transmission of the offline data to the management device 80 in S39. Having received the report, the management device 80 reports completion of transmission of the offline data to the analysis device 60 in the relay device 2 with device number Y (S17 in FIG. 15).

[0166] On the other hand, if there is no report of completion of reception from the analysis device 60 (determination of NO in S35), the relay device 2 proceeds to S36 and retransmits the offline data. The relay device 2 determines in S37 whether or not the retransmission in S36 is being performed for the second time. If the retransmission is not being performed for the second time, that is, if the retransmission is being performed for the first time (determination of NO in S37), the relay device 2 returns to S34 and executes processing of the offline data. Then, in response to receiving a data reception completion report from the analysis device 60 within the timeout period (determination of YES in S35), the relay device 2 reports to the management device 80 that the transmission processing of the offline data is completed (S39).

[0167] On the other hand, if this is the second retransmission, the relay device 2 does not retransmit a third time, and reports to the management device 80 in S38 that the transmission of the offline data has failed. The management device 80, which has received this report, transmits a notification to the analysis device 60 that the relay device 2 with device number Y is unable to transmit the offline data (S16, S17 in FIG. 15). In response to receiving the notification that the offline data cannot be transmitted, the analysis device 60 ends the process of requesting offline data from the relay device 2 with device number Y (S02, S05 in FIG. 14).

[0168] <Effects> Next, the effect of the offline data transmission process according to the present embodiment will be described.

[0169] Fig. 17 is a diagram for explaining the arrival timing of a frame at the fifth switch 3_5, and is a diagram to be compared with Fig. 7. The arrows in Fig. 17 indicate sampling timings. The period Ta between two adjacent sampling timings indicates a sampling period. Fig. 17 assumes a case where the analysis device 60 requests the first relay devices 2_1, 2_5 to transmit offline data (see Fig. 8).

[0170] 17, similarly to FIG. 7, reception period TG1 indicates a period during which frames F1 and F2 belonging to group G1 of each relay device 2 arrive. Reception period TG2 indicates a period during which frames F3 and F4 belonging to group G2 of each relay device 2 arrive. Reception periods TG1 and TG2 correspond to reception periods of high-speed cycle data (electrical quantity data measured at the latest sampling timing). Reception period TG3 indicates a period during which frames FX belonging to group G3 arrive from each monitoring device 5.

[0171] Reception periods TG4-1, TG4-2, TG4-3, and TG4-4 indicate periods during which frames FY of the relay device 2 requested by the analysis device 60 arrive. Specifically, each reception period TG4 indicates a period during which offline data having a unit data amount (e.g., 1000 bytes) arrives. The number of reception periods TG4 in each sampling period corresponds to the number of transmission data.

[0172] 17, the frame FY including the offline data of the first relay device 2_1 is transmitted in two separate sampling periods. The number of transmission data of the offline data in each sampling period is "2".

[0173] After the transmission of the offline data in the first relay device 2_1 is completed, the frame FY including the offline data of the first relay device 2_5 is transmitted in two separate sampling periods. The number of transmission data of the offline data in each sampling period is "2". In reality, however, the management device 80 performs a process such as calculation of a transmission condition between the transmission process of the offline data in the first relay device 2_1 and the transmission process of the offline data in the first relay device 2_5, and therefore these two transmission processes are not performed consecutively.

[0174] As described above, in this embodiment, each of the first relay devices 2_1 and 2_5 to which offline data is requested transmits the offline data in response to a transmission request provided by the management device 80. The management device 80 first transmits a transmission request to the first relay device 2_1, and transmits a transmission request to the first relay device 2_5 in response to the completion of the transmission of the offline data in the first relay device 2_1. Therefore, as shown in FIG. 17, the first relay device 2_1 and the first relay device 2_5 transmit offline data using different sampling periods. This makes it possible to prevent the arrival timing of the frame FY including the offline data of the first relay device 2_1 and the frame FY including the offline data of the first relay device 2_5 at the fifth switch 3_5 from concentrating in a short period of time in each sampling period. Therefore, it is possible to prevent congestion of the offline data from occurring in the fifth switch 3_5.

[0175] Moreover, according to this embodiment, in each sampling period, each of the first relay devices 2_1, 2_5 transmits offline data according to the transmission conditions (transmission delay time and number of transmission data) specified by the management device 80. The management device 80 calculates the transmission delay time and the number of transmission data of each relay device 2 based on the frame reception information of each switch 3 so that the reception period of the offline data in the fifth switch 3_5 does not overlap with the reception period of the high speed cycle data. Therefore, a waiting state of the frame of the high speed cycle data does not occur in the fifth switch 3_5, so that a delay in the reception timing of the high speed cycle data can be prevented. This makes it possible to prevent an interruption of the current operation calculation (i.e., an interruption of protection) due to a delay or loss of the high speed cycle data.

[0176] The configurations exemplified as the above-mentioned embodiments are examples of the configurations of the present disclosure, and may be combined with other known techniques. It is also possible to modify the configuration, such as omitting some parts, without departing from the gist of the present disclosure.

[0177] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Unless there is a contradiction, at least two of the embodiments disclosed herein may be combined. The technical scope of the present disclosure is indicated by the claims, not the description of the above-mentioned embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0178] Various aspects of the present disclosure are summarized below as appendices.

[0179] (Appendix 1) A plurality of network switches respectively provided on a plurality of terminals; For each of the plurality of network switches connected in a loop, a plurality of relay devices are connected to the network switch; an analysis device connected to any one of the plurality of network switches; a management device connected to any one of the plurality of network switches; For each of the plurality of network switches, each of the plurality of relay devices connected to the network switch transmits electrical quantity data measured at a sampling timing to the network switch; Each of the network switches transmits the received electrical quantity data to the other network switches; The management device collects reception information of data including the electrical quantity data in each of the network switches, When an accident occurs in a power transmission line protected by a first relay device among the plurality of relay devices, the analysis device transmits a first transmission request for accident analysis data for the plurality of first relay devices to the management device; the management device generates a plurality of second transmission requests based on the reception information in response to the first transmission request from the analysis device, and transmits the generated plurality of second transmission requests to each of the first relay devices in turn; A protection relay system, wherein each of the first relay devices transmits the fault analysis data to the analysis device in accordance with the received second transmission request.

[0180] (Appendix 2) 2. The protection relay system of claim 1, wherein the management device calculates, for each of the first relay devices, transmission conditions for the fault analysis data based on the received information, and transmits the second transmission request including the calculated transmission conditions to each of the first relay devices.

[0181] (Appendix 3) The protection relay system according to claim 2, wherein the transmission conditions include a transmission delay time, which is a delay time from the sampling timing to a timing at which the fault analysis data is transmitted, and a transmission data count, which is the number of times the fault analysis data having a unit data amount is continuously transmitted within one sampling period.

[0182] (Appendix 4) For each of the plurality of network switches, the first relay device connected to the network switch transmits, at a first timing when a first time has elapsed from the sampling timing, first electrical quantity data measured at the sampling timing to the network switch; For each of the plurality of network switches, a second relay device connected to the network switch transmits, at a second timing when a second time has elapsed from the sampling timing, second electrical quantity data measured at the sampling timing to the network switch; 4. The protective relay system of claim 3, wherein, for each of the plurality of network switches, the first relay device that is connected to the network switch and receives the second transmission request transmits the fault analysis data to the network switch at a transmission delay timing that is the transmission delay time after the sampling timing.

[0183] (Appendix 5) 5. The protective relay system of claim 4, wherein a period in which the first relay device transmits the first electrical quantity data, a period in which the second relay device transmits the second electrical quantity data, and a period in which the first relay device transmits the fault analysis data do not overlap with each other.

[0184] (Appendix 6) 6. The protective relay system of claim 4 or 5, wherein in a network switch to which the analysis device is connected, a period for receiving the first electrical quantity data, a period for receiving the second electrical quantity data, and a period for receiving the fault analysis data do not overlap with each other.

[0185] (Appendix 7) The management device, for each of the first relay devices, Calculating a maximum time for receiving data at the network switch to which the analysis device is connected and a transmission time required for data transmitted from the network switch to which the first relay device is connected to arrive at the network switch to which the analysis device is connected based on the reception information; 7. The protection relay system according to claim 3, wherein the transmission delay time is calculated based on the calculated maximum reception time and the calculated transmission time.

[0186] (Appendix 8) The management device, for each of the first relay devices, calculating a transmission time during which the first relay device can transmit the accident analysis data by subtracting the transmission delay time and the transmission time from a sampling period; setting a transmission time during the sampling period during which the first relay device transmits the accident analysis data from the transmission available time; The protection relay system according to claim 7, wherein the number of transmission data is calculated based on the transmission time and the unit data amount.

[0187] (Appendix 9) the management device sets an order of transmission of the accident analysis data to the first relay devices, and transmits the second transmission request to the first relay device having the first priority; the first relay device having the first priority reports completion of transmission to the management device in response to completion of transmission of the accident analysis data; 9. The protection relay system according to any one of Supplementary Note 1 to Supplementary Note 8, wherein the management device transmits the second transmission request to the first relay device of the second priority in response to receiving a report of transmission completion from the first relay device of the first priority.

[0188] (Appendix 10) The reception information includes information regarding a timing of receiving data at each of the network switches, an amount of the data, and a destination and a source of the data, 10. The protection relay system according to any one of Supplementary Note 1 to Supplementary Note 9, wherein each of the network switches stores the received information in an internal memory, transmits the received information to the management device in response to a transmission request from the management device, and resets the internal memory in response to a reset request from the management device.

[0189] (Appendix 11) a synchronization device connected to any one of the plurality of network switches, 11. The protection relay system according to any one of Supplementary Note 1 to Supplementary Note 10, wherein for each of the plurality of network switches, each of the plurality of relay devices connected to the network switch synchronizes the sampling timing of the relay device with the sampling timing of other relay devices by synchronizing the time of the relay device with the time of the synchronization device based on time synchronization data received from the synchronization device via the network switch. [Explanation of symbols]

[0190] 2 relay device, 3 switch, 5 monitoring device, 20 synchronizer, 32 auxiliary transformer, 35 A / D conversion section, 40,70 calculation processing section, 41,71 CPU, 42,72 RAM, 43,73 ROM, 44,74 bus, 45 sampling pulse generating circuit, 50,75 communication circuit, 55 digital output circuit, 56 digital input circuit, 60 analysis device, 80 management device, 1000 protection relay system, E1~E5 terminals, F1~F4,FX,FY frames, G1~G4 groups, NW network, R communication path.

Claims

1. A plurality of network switches respectively provided on a plurality of terminals; For each of the plurality of network switches connected in a loop, a plurality of relay devices are connected to the network switch; an analysis device connected to any one of the plurality of network switches; a management device connected to any one of the plurality of network switches; For each of the plurality of network switches, each of the plurality of relay devices connected to the network switch transmits electrical quantity data measured at a sampling timing to the network switch; Each of the network switches transmits the received electrical quantity data to the other network switches; The management device collects reception information of data including the electrical quantity data in each of the network switches, When an accident occurs in a power transmission line protected by a first relay device among the plurality of relay devices, the analysis device transmits a first transmission request for accident analysis data for the plurality of first relay devices to the management device; the management device generates a plurality of second transmission requests based on the reception information in response to the first transmission request from the analysis device, and transmits the generated plurality of second transmission requests to each of the first relay devices in turn; A protection relay system, wherein each of the first relay devices transmits the fault analysis data to the analysis device in accordance with the received second transmission request.

2. 2. The protective relay system according to claim 1, wherein the management device calculates, for each of the first relay devices, transmission conditions for the accident analysis data based on the received information, and transmits the second transmission request including the calculated transmission conditions to each of the first relay devices.

3. 3. The protection relay system according to claim 2, wherein the transmission conditions include a transmission delay time, which is a delay time from the sampling timing to a timing at which the fault analysis data is transmitted, and a transmission data count, which is a number of times that the fault analysis data having a unit data amount is continuously transmitted within one sampling period.

4. For each of the plurality of network switches, the first relay device connected to the network switch transmits, at a first timing when a first time has elapsed from the sampling timing, first electrical quantity data measured at the sampling timing to the network switch; For each of the plurality of network switches, a second relay device connected to the network switch transmits, at a second timing when a second time has elapsed from the sampling timing, second electrical quantity data measured at the sampling timing to the network switch; 4. The protective relay system according to claim 3, wherein, for each of the plurality of network switches, the first relay device that is connected to the network switch and receives the second transmission request transmits the fault analysis data to the network switch at a transmission delay timing at which the transmission delay time has elapsed from the sampling timing.

5. 5. The protective relay system according to claim 4, wherein a period in which the first relay device transmits the first electrical quantity data, a period in which the second relay device transmits the second electrical quantity data, and a period in which the first relay device transmits the fault analysis data do not overlap with each other.

6. 5. The protective relay system according to claim 4, wherein in a network switch to which the analysis device is connected, a period for receiving the first electrical quantity data, a period for receiving the second electrical quantity data, and a period for receiving the fault analysis data do not overlap with each other.

7. The management device, for each of the first relay devices, Calculating a maximum time for receiving data at the network switch to which the analysis device is connected and a transmission time required for data transmitted from the network switch to which the first relay device is connected to arrive at the network switch to which the analysis device is connected based on the reception information; The protection relay system according to claim 3 , wherein the transmission delay time is calculated based on the calculated maximum reception time and the calculated transmission time.

8. The management device, for each of the first relay devices, calculating a transmission time during which the first relay device can transmit the accident analysis data by subtracting the transmission delay time and the transmission time from a sampling period; setting a transmission time during the sampling period during which the first relay device transmits the accident analysis data from the transmission available time; The protection relay system according to claim 7 , wherein the number of pieces of transmission data is calculated based on the transmission time and the unit data amount.

9. the management device sets an order of transmission of the accident analysis data to the first relay devices, and transmits the second transmission request to the first relay device having the first priority; the first relay device having the first priority reports completion of transmission to the management device in response to completion of transmission of the accident analysis data; 2. The protection relay system according to claim 1, wherein the management device transmits the second transmission request to the first relay device of the second priority in response to receiving a report of completion of transmission from the first relay device of the first priority.

10. The reception information includes information regarding a timing of receiving data at each of the network switches, an amount of the data, and a destination and a source of the data, 2. The protection relay system according to claim 1, wherein each of the network switches stores the received information in an internal memory, transmits the received information to the management device in response to a transmission request from the management device, and resets the internal memory in response to a reset request from the management device.

11. a synchronization device connected to any one of the plurality of network switches, 2. The protection relay system according to claim 1, wherein, for each of the plurality of network switches, each of the plurality of relay devices connected to the network switch synchronizes the sampling timing of the relay device with the sampling timing of other relay devices by synchronizing the time of the relay device with the time of the synchronization device based on time synchronization data received from the synchronization device via the network switch.

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