JP6659208B2 - Loop type protection relay system - Google Patents

Description

  The embodiment of the present invention relates to a loop protection relay system in which a plurality of relay terminals are connected in a loop by a communication line.

  Generally, a power system is provided with a protection relay system. The protection relay system is applied to various uses, and a transmission line protection system and a system stabilization control system are typical. The transmission line protection system detects an accident on the transmission line or bus, cuts off the accident section, and prevents the propagation of the accident. In addition, the system stabilization control system detects a system accident at a power generation substation and predicts a system instability event such as frequency step-out, thereby stabilizing the power system.

  In these protection relay systems, a relay terminal is provided at each terminal of a transmission line section or a substation. Each relay terminal measures and inputs electric quantity data such as a current value, a voltage value, and contact information, forms a communication frame including the electric quantity data, and distributes the communication frame to other relay terminals.

  Thereby, the relay terminals can mutually exchange electric quantity data and share the electric quantity data. Each relay terminal is equipped with an operation unit, and executes various protection operations such as a current differential operation and a stability operation using electric quantity data measured at the same time. The measurement timing of the electric quantity data is based on a sampling pulse signal generated by dividing a hardware clock.

  The sampling pulse signal can expand and contract the pulse signal width by finely adjusting the frequency division value such as (reference value +1) or (reference value -1), and can synchronize with the pulse signal edge of another relay terminal. . The above synchronization method is called sampling synchronization, and performing sampling synchronization is one of the features of a protection relay system to which a relay terminal is applied.

  Conventionally, the communication line of the protection relay system is 54 Kbps or 1.5 Mbps. Therefore, for example, when transferring instantaneous value data in a cycle of an electrical angle of 30 ° (1.67 ms cycle in a 50 Hz system, 1.38 ms cycle in a 60 Hz system), the length of one information frame is extremely large, such as 90 bits or 119 bits. Only small capacity can be handled. Such a low communication speed of the communication line has been a factor that restricts the function and performance of the relay terminal.

  Therefore, in recent years, studies have been made to apply a high-speed Ethernet communication line such as 100 Mbps or 1000 Mbps as a communication line for a protection relay. By using an Ethernet communication line, the amount of information to be handled can be significantly increased, and various functions can be mounted on the relay terminal to improve the performance. In addition, if an Ethernet communication line is used, the transmission interval of a communication frame can be transferred in a short cycle, and therefore, it is expected that the accuracy of the instantaneous value is improved.

  In an Ethernet communication network, a loop topology in which terminals are connected and connected in a loop is generally used. When configuring a loop topology, it is important to take measures to prevent communication frames from illegally circulating through a loop communication path. As a specific measure, setting of a loop end or route control by L2SW to which STP (Spanning Tree Protocol) or RSTP (Rapid STP) of a relay device is applied may be mentioned.

Japanese Patent No. 5172106 Japanese Patent No. 5127482

2008 IEEJ National Convention No.6-302 2012 IEEJ National Convention No.6-238

As described above, in the loop topology to which the Ethernet communication is applied, the setting of the loop end or the path control by the L2SW is performed, but there are the following problems. Therefore, it has been difficult to apply the setting of the loop end and the path control using the L2SW to the loop-type protection relay system.
(1) When a loop end is set, if a line failure (communication disconnection or device failure such as SW) occurs at a part other than the loop end, a section where communication becomes impossible between the relay terminals is created, and the operation of the system can be maintained. become unable.

(2) When setting a loop end, the loop topology is substantially equivalent to the bus topology. In the bus topology, a path connected to a relay terminal closer to the center of the communication path is likely to have a higher communication load and a higher communication load. As a result, delay fluctuations increase, and it becomes difficult to obtain uniform synchronization accuracy in each relay terminal, resulting in a decrease in synchronization accuracy.

(3) Regarding the communication path between the relay terminals of the master and slave, it is necessary to set the forward path and the return path to be the same path. However, when the path is controlled by the L2SW, the communication path may be different between the forward path and the return path. As a result, the communication delay time cannot be accurately calculated, and sampling synchronization cannot be performed.

(4) In the case of route control using the L2SW, when the SW detects a line failure, a new communication path can be configured by the route control to restore communication. It takes ten to several hundred milliseconds. In other words, the system must stop for several tens to several hundreds of milliseconds until the restoration is completed. In addition, since the communication path changes by newly configuring the communication path, the communication delay time also changes accordingly. For this reason, sampling synchronization accuracy may be disturbed.
(5) Since the path control setting by the relay device such as the L2SW is indispensable, there is a possibility that an incorrect operation may cause an incorrect operation.

  An embodiment of the present invention is proposed to solve the above-mentioned problem, and eliminates the need for setting a loop end and controlling a path by using an L2SW. It is an object of the present invention to provide a loop-type protection relay system capable of performing the following.

In order to achieve the above object, an embodiment of the present invention arranges a plurality of relay terminals for measuring electric quantity data in a power system, and connects the relay terminals in a loop without setting a loop end with a communication line. Then, in a loop-type protection relay system that shares the electric quantity data by distributing a first communication frame including the electric quantity data to the other relay terminals, each relay terminal includes the following components. ing.

(A) Two communication ports.
(B) a communication driver for transmitting and receiving the communication frame to and from the other relay terminals.
(C) an operation unit that performs a predetermined protection operation using the electric quantity data.

The communication driver includes the following components.
(D) receiving the electric quantity data from the arithmetic unit, generating two communication frames storing the same electric quantity data based on the electric quantity data, and transmitting the two communication frames from the communication ports of the two lines before and after the connection; A transmission processing unit that transmits the same communication frame to each of the relay terminals.
(E) a reception processing unit that receives the communication frame from each of the relay terminals before and after the connection via the two communication ports.

The reception processing unit includes the following components.
(F) the first communication frame received through the communication port based on a predetermined condition, and the first communication frame is transmitted to the communication port on the side opposite to the side that received the first communication frame; A relay necessity determining unit that determines whether to relay the communication frame.
(G) a relay sending unit that sends the first communication frame to the communication port when the relay necessity determination unit determines that the first communication frame is to be relayed;
(H) a communication frame notification unit that notifies the arithmetic unit of the first communication frame regardless of a relay determination result of the relay necessity determination unit.
(I) Further, each of the relay terminals performs synchronous communication in a second communication frame including synchronization control data at both of the communication ports of the two lines, and changes in communication delay time in the synchronous communication at each of the communication ports. The synchronous communication of the communication port having the smaller fluctuation of the communication delay time among the synchronous communication of the two communication ports is adopted as the synchronous communication by the line including the communication port.

FIG. 2 is a block diagram of the first embodiment. FIG. 2 is a block diagram of the relay terminal according to the first embodiment. The figure which shows the example of a format of a communication frame. The figure which shows the example of a format of a communication frame. FIG. 10 is a block diagram of a second embodiment. FIG. 10 is a block diagram of a third embodiment. The figure which shows the example of a format of a communication frame. FIG. 13 is a block diagram of a fourth embodiment.

(1) First embodiment (configuration and operation)
A first embodiment will be specifically described with reference to FIGS. 1 and 2 as an embodiment according to the present invention. FIG. 1 is a block diagram of the first embodiment.

(Overview)
As shown in FIG. 1, the loop-type protection relay system according to the first embodiment has seven relay terminals Ry1 to Ry7 arranged at key points in a power system, and loops the relay terminals Ry1 to Ry7 through a communication line 2. Connected. As the communication line 2, an Ethernet communication line is employed. Each of the relay terminals Ry1 to Ry7 measures its own electric data and distributes a communication frame F including electric data to and from the other relay terminals Ry1 to Ry7 connected to the communication line 2. As a result, all the relay terminals Ry1 to Ry7 or any necessary relay terminals Ry1 to Ry7 can share the electric quantity data measured by each of the relay terminals Ry1 to Ry7.

  The relay terminals Ry1 to Ry7 have two communication ports 8 and 9, and employ a two-system communication path. Here, one communication route is called an A route and the other communication route is called a B route. The communication connection with each of the relay terminals Ry1 to Ry7 is performed by connecting the A route of each of the relay terminals Ry1 to Ry7 to the B route of the relay terminals Ry1 to Ry7 before and after being connected in a loop, thereby forming a loop communication. Configuration will be adopted.

  Each of the relay terminals Ry1 to Ry7 transmits the communication frame F from the communication port 8 (9) to the connected relay terminals Ry1 to Ry7. Upon receiving the transmitted communication frame F, the relay terminals Ry1 to Ry7 receive the communication frame F at the communication port 9 (8) and relay the communication frame F to the other communication port 8 (9) based on a predetermined condition.

  For example, the relay terminal Ry1 transmits the communication frame F from the communication port 8 to the communication port 9 of the relay terminal Ry2 via the route A. The relay terminal Ry2 relays the received communication frame F from the communication port 9 to the communication port 8. By repeating this, the communication frame circulates in the order from the relay terminal Ry1 to the relay terminals Ry2, Ry3, Ry4, Ry5, Ry6, and Ry7 (clockwise in FIG. 1).

  The relay terminal Ry1 receives the communication frame F from the communication port 9 of the relay terminal Ry2 at the communication port 8 via the route A, and relays the received communication frame F to the communication port 9. Then, the relay terminal Ry1 transmits the communication frame F from the communication port 9 to the communication port 8 of the relay terminal Ry7 via the route B. By repeating this, the loop communication configuration in which the communication frame F is circulated in the order of the relay terminals Ry1 to Ry7, Ry6, Ry5, Ry3, and Ry2 (counterclockwise in FIG. 1) is reversed.

  In the first embodiment as described above, the relay terminals Ry1 to Ry7 are connected in a loop by the communication line 2 without performing the setting of the loop end or the path control by the L2SW. The communication line 2 here may be in a form capable of full-duplex communication (Full Duplex), and may be a general Ethernet communication cable such as a UTP (electric) cable or an optical cable.

(Relay terminal)
Each of the relay terminals Ry1 to Ry7 includes an arithmetic unit 10, a communication driver 11, and NICs (Network Interface Controllers) 12, 13. Each of the relay terminals Ry1 to Ry7 performs synchronous communication using the communication frame F at both of the two communication ports 8 and 9, and compares the fluctuation of the communication delay time in the synchronous communication at each of the communication ports 8 and 9, Synchronous communication with less fluctuation of communication delay time is adopted.

(Communication frame)
Here, before describing each component of the relay terminals Ry1 to Ry7, the type of the communication frame F will be described. Examples of the communication frame F include an electric quantity frame including electric quantity data and a synchronization frame including synchronization control data.

(Electric quantity frame)
The electric quantity frame is a frame that stores measured electric quantity data and any additional information such as control and monitoring states of the apparatus, and includes calculation data for each operation unit 10, a sampling address SA and a measurement timing difference. It is a summary of. When the arithmetic unit 10 of each of the relay terminals Ry1 to Ry7 receives such an electric quantity frame from two communication paths, if both of the communication paths are sound, the electric quantity frame is redundantly received.

(Synchronous frame)
On the other hand, the synchronization frame is a frame that stores synchronization control data such as synchronization master / slave terminal numbers, synchronization frame transmission / reception timing (time) information, synchronization command information, and response type information.

(Calculation unit)
When the arithmetic unit 10 of each of the relay terminals Ry1 to Ry7 receives the above-mentioned synchronization frame, it is necessary to perform a round-trip synchronous communication between the synchronization master-slave relay terminals Ry1 to Ry7 and make the round-trip communication path the same. is there. The calculation unit 10 calculates a synchronization error and a communication delay time for the synchronization frame transmitted from the A route using the synchronization frame arriving at the A route.

  Similarly, for the synchronization frame transmitted from the B route, the calculation unit 10 calculates the synchronization error and the communication delay time using the synchronization frame received on the B route. Therefore, the arithmetic unit 10 obtains a synchronization error and a communication delay time for two routes. At this time, in the relay terminals Ry1 to Ry7 of the present embodiment, as described above, the one with less fluctuation of the communication delay time is adopted.

  The calculation unit 10 is application software for monitoring the power system and determining an accident using the electric quantity data, and includes various types such as a current differential calculation and a stability determination calculation. A description of specific types and processing contents of the application software is omitted here. The arithmetic unit 10 of the relay terminal Ry1 can acquire the electric quantity frame including the electric quantity data measured by the other relay terminals Ry2 to Ry7 by the communication driver 11 transmitting and receiving the electric quantity data, and A predetermined calculation is performed using the above.

(NIC)
The NICs 12 and 13 are provided before the communication ports 8 and 9. The NICs 12 and 13 are generally of a store-and-forward type. In the NICs 12 and 13, an invalid frame in which the FCS (frame check sequence code) included in the communication frame F has an error is discarded.

(Communication driver)
The communication driver 11 is a part that transmits and receives the communication frame F between the relay terminals Ry1 to Ry7. The components of the communication driver 11 will be described with reference to FIG. As shown in FIG. 2, the communication driver 11 includes a transmission processing unit 14, a reception processing unit 15, and two queues 16 and 17.

(queue)
The queues 16 and 17 are provided before the NICs 12 and 13. The queues 16 and 17 transmit the communication frames F in order. The queues 16 and 17 wait for the transmission of the communication frame F. If the relay time fluctuates, the communication delay time fluctuates. At this time, if the communication frame F is a synchronization frame, the synchronization accuracy of the relay may be disturbed.

  Therefore, a plurality of queues 16 and 17 are separately arranged for the electric quantity frame and for the synchronous frame. The queues 16 and 17 for the synchronization frame are provided independently. Therefore, in the relay of the synchronous frame, regardless of the presence or absence of the transmission in-process state in the NICs 12 and 13, the NICs 12 and 13 are allowed to stay for a predetermined fixed time Ta (the maximum frame size communication time used in the system + margin α). Relay from.

  The relay delay time of the synchronization frame can be obtained by the transmission time Ts + Ta of the synchronization frame size, and this time is uniform. Further, the queues 16 and 17 are controlled not to transmit the electric quantity frame during the period in which the synchronization frame is retained.

(Transmission processing unit)
The transmission processing unit 14 receives the electric quantity data from the arithmetic unit 10, generates two communication frames F storing the same electric quantity data based on the electric quantity data, and directs the communication frames F to the A route and the B route. The communication frame F is transmitted from the communication ports 8 and 9. The communication frame F transmitted from each route differs in the transmission route and the source MAC.

  The communication frame F of the A route transmitted from the transmission processing unit 14 is temporarily stored in the queue 16, waits for transmission, and is transmitted to the A route via the NIC 12. Further, the communication frame F of the B route transmitted from the transmission processing unit 14 is temporarily stored in the queue 17, waits for transmission, and is transmitted to the B route via the NIC 13.

(Reception processing unit)
The reception processing unit 15 receives the communication frame F from the A route and the B route via the communication ports 8 and 9. The reception processing unit 15 includes a relay necessity determination unit 18, a relay transmission unit 19, and a reception frame notification unit 20 as components. The reception frame notification unit 20 is a communication frame notification unit that notifies the calculation unit 10 of the communication frame F.

(Relay necessity judgment section)
The relay necessity determination unit 18 determines whether or not to relay the received communication frame F to a communication port different from the one that received the communication frame F, based on a predetermined condition. The relay necessity determination unit 18 starts the relay necessity determination at the time when a part of the communication frame F is received. Here, the conditions (A) to (D) for not relaying the communication frame F are set as follows.

(A) If the destination MAC is addressed to the own station, do not relay.
(B) If the source MAC is the local station, do not relay.
(C) If the relay TTL is equal to or greater than the upper limit, no relay is performed.
(D) If the relay TTL is 0, do not relay.
The destination MAC, the source MAC, and the relay TTL will be described in the format of a communication frame F described later.

  When the communication frame F satisfies at least one of the above conditions (A) to (D), the relay necessity determination unit 18 determines that the relay to the communication ports 8 and 9 is not performed. In addition, when the communication frame F does not satisfy all of the conditions (A) to (D), the relay necessity determination unit 18 determines that the communication frame F is relayed to the communication ports 8 and 9.

(Relay transmission section)
When the relay necessity determining unit 18 determines that the communication frame F is to be relayed to the communication ports 8 and 9, the relay sending unit 19 subtracts the relay TTL included in the received frame and regenerates the communication frame F as a relay frame. , And sends the regenerated communication frame F as a relay frame to the queues 16 and 17 of the communication ports 8 and 9 as relay destinations.

(Received frame notification unit)
Regardless of the relay determination by the relay necessity determining unit 18, the received frame notifying unit 20 adopts the communication frame F as the received frame and notifies the arithmetic unit 10 of the received frame. At this time, if both routes A and B are sound, the same received frame arrives at the arithmetic unit 10 from both routes.

  When the same received frame arrives at the arithmetic unit 10, if the received frame is an electric quantity frame, overlapping reception is performed. Therefore, it is necessary to discard one of the overlapping received frames. Therefore, the received frame notifying section 20 stores the latest value of the transmission serial number in the communication frame F, and discards the communication frame F having the same transmission serial number as that. Therefore, the reception frame notification unit 20 notifies the calculation unit 10 of only the communication frame F that has arrived first as a reception frame.

(Format of communication frame)
Next, the format of the communication frame F will be described with reference to FIGS. FIG. 3 is a format example in a case where UDP / IP is applied to the communication frame F, and FIG. 4 is a format example in a case where a RAW Ethernet in which user data is provided after the Ethernet header is used.

  Among such formats, it is more versatile to employ UDP / IP as an interface of the arithmetic unit 10 so that communication can be managed by an IP address. On the other hand, RAW Ether can be expected to reduce the communication load and the relay time because the IP header and the UDP header are not provided. Both formats may be selected according to the required performance of the system.

(Destination MAC, source MAC)
In the format of the communication frame F, the destination MAC and the source MAC are MAC addresses representing the destination and the source, and are stored together with the type in the Ethernet header. The MAC address is hardware-specific information. However, since the MAC address is difficult to manage in the application software of the arithmetic unit 10, the destination terminal numbers and the transmission terminal numbers of the relay terminals Ry1 to Ry7 are added to the user data area. Further, when the terminal numbers of the relay terminals Ry1 to Ry7 can be substituted by the IP addresses as in the case of the UDP / IP frame, it is not necessary to add the terminal numbers of the relay terminals Ry1 to Ry7.

(type)
The type in the format of the communication frame F is the Ethernet frame type, and indicates the type of the upper layer protocol of the Ethernet layer. Representative types include IPV4: 0800, ARP: 0806, SNMP: 814C, NetBIOS: 8191 and the like.

(IP header, UDP header)
Further, the format of the communication frame F includes an IP header and a UDP header. The IP header includes a destination IP address, a source IP address, an IP field size, and the like, and the UDP header includes a destination port number, a source port number, a UDP field size, and the like. The port number is for identifying a synchronization frame and an electric quantity frame.

(Characteristics of arrangement of format of communication frame F)
In the format of the communication frame F, a user data area is provided, which includes electric quantity data or synchronization control data. The user data area includes a relay TTL, a transmission route, a transmission serial number, a destination terminal number, and a transmission terminal number. In the present embodiment, the relay TTL, the transmission route, the transmission serial number, the destination terminal number, and the transmission terminal number are arranged forward of the format in the user data area, that is, before the electric quantity data or the synchronization control data. There are features.

(Relay TTL)
The relay TTL is information for preventing unnecessary traveling. The relay TTL is information indicating the maximum number of relays for relaying the communication frame F received by the relay terminals Ry1 to Ry7 to another route, and is constant by subtracting the TTL of the communication frame F each time relaying is performed. It does not relay more than the number of times. In such a relay TTL, the number of relays in a loop route is set when the communication frame F to be transmitted is generated.

  For example, as shown in FIG. 1, if relay terminals Ry1 to Ry7 have a seven-terminal configuration, if relaying is performed five times, communication frame F can be distributed to all relay terminals Ry1 to Ry7. Therefore, the initial value of TTL is (maximum number of terminals). -2). Since the TTL of the communication frame F is subtracted and updated, the FCS of the communication frame F, that is, the frame check sequence code is correspondingly recalculated and updated.

(Sending route)
In the format of the communication frame F, the transmission route is information used for setting either the A route or the B route as a route for transmitting the communication frame F and determining the transmission / reception route of the synchronization frame. As described above, in the sampling synchronization control, since the communication delay time of the forward path or the return path of the synchronous communication needs to be the same, in the present embodiment, the synchronization processing is performed by the synchronization frame of the A route transmission and the synchronization frame of the B route reception. Is going.

(Sending serial number)
In the format of the communication frame F, the transmission serial number is information used for discarding the late arrival of the electric quantity frame when a reception frame arrives from both routes. Based on this information, the received frame notifying section 20 discards the later received one of the duplicated received frames.

(Destination terminal number, sending terminal number)
In the format of the communication frame F, the destination terminal number and the transmission terminal number are information used for identification as the terminal numbers of the respective relay terminals. That is, when data is exchanged between the arithmetic unit 10 and the communication driver 11, the destination terminal number is information for identifying which relay terminal is the electric quantity data. Further, the transmission terminal number is information for identifying from which relay terminal the terminal has been received.

(Communication frame communication processing)
The communication processing of the communication frame F in the present embodiment will be described with reference to FIG. 2 using the relay terminal Ry1 as an example. The transmission processing unit 14 of the relay terminal Ry1 receives the self-end electricity amount data measured by the arithmetic unit 10 in the cycle of the electrical angle of 30 °, sets the destination MAC to the broadcast address, and sends to the relay terminals Ry2 and Ry7 connected before and after the destination MAC. The communication ports 8 and 9 transmit a communication frame F including own-end electricity amount data toward the A route and the B route. Note that, to the transmission source MAC of the communication frame F, the MAC address of the NIC 12 is added to the transmission frame from the communication port 8 and the MAC address of the NIC 13 is added to the transmission frame from the communication port 9. Similarly, the relay terminals Ry2 to Ry7 transmit the communication frame F to the preceding and following relay terminals.

  The reception processing unit 15 of each of the relay terminals Ry1 to Ry7 receives the communication frame F from the A route and the B route via the communication ports 8 and 9, and receives the received frame regardless of the relay determination result of the relay necessity determination unit 18. The notification unit 20 employs the communication frame F as a reception frame, and notifies the calculation unit 10 of the reception frame. The arithmetic unit 10 that has acquired the received frame receives the electric quantity data of the own end and the other relay terminals Ry1 to Ry7, and performs an accident determination calculation of the system from these electric quantity data.

(Synchronous communication)
Synchronous communication will be described using an example in which the relay terminal Ry1 is a synchronization main terminal and the relay terminals Ry2 to Ry7 are synchronization slave terminals. The synchronization frame can be either a broadcast frame or a unicast frame. Here, an example in which a unicast frame is applied will be described. The relay terminal Ry2 of the synchronization slave transmits a synchronization request frame to the relay terminal Ry1 of the master at intervals of, for example, one second. The period of the synchronous communication may be determined according to the required synchronization accuracy and the accuracy of the crystal oscillator of the relay terminal.

  The synchronization request frame transmitted from the relay terminal Ry2 arrives at the relay terminal Ry1 in the order of the A route and the B route. The reception timing of the synchronization request frame differs between the A route and the B route depending on the communication distance of the route to the main terminal relay terminal Ry1 and the number of relays. Therefore, each of the relay terminals Ry1 to Ry7 separately measures and stores the reception timing of the synchronization request frame received through each route. The relay terminal Ry1 that has received the synchronization request frame from the relay terminal Ry2 measures the reception timing, and then adds the reception timing to the synchronization response frame and returns it to the relay terminal Ry2.

  At this time, it is not necessary to return the synchronization request frame from both the route A and the route B at the same timing, and the synchronization response frame may be returned from the route receiving the synchronization request frame. Alternatively, the reception timings of two routes may be stored after the synchronization request frame is received by both routes, and the reception timing may be simultaneously distributed to both routes.

  Since the relay terminal Ry2 that receives the synchronization response frame also receives the call from both the A route and the B route, the transmission and reception timing of the synchronization frame of both routes can be acquired by measuring the reception timing of both routes. Thereby, the synchronization error and the communication delay time can be calculated.

(effect)
In the present embodiment, a protection system configuration in which seven relay terminals Ry1 to Ry7 are communicatively connected in a loop becomes possible, and a communication frame F is transmitted from two communication routes, an A route and a B route, thereby enabling one communication. Even if a failure occurs in one of the communication line 2 and the relay device (including the relay terminals Ry1 to Ry7) included in the path, the communication frame F can be reliably transmitted and received using the other communication path. Therefore, it is possible to maintain the sharing of the electric quantity data, and it is possible to obtain high reliability.

  That is, according to the present embodiment, a protection system configuration in which the relay terminals Ry1 to Ry7 are communicatively connected in a loop shape without setting a loop end is possible, and a communication failure occurs in one place on the loop communication path. Even if it occurs, operation can be maintained. Moreover, since the communication frame F is transmitted using the two communication paths, the communication delay time between the relay terminals Ry1 to Ry7 is less than half the time required for one round of the loop path. Therefore, high-speed response of the relay processing can be realized.

  In this embodiment, since no loop end is set, there is no relay terminal Ry1 to Ry7 that can be called the center of the communication path. Therefore, there is no problem that the communication load of some relay terminals Ry1 to Ry7 increases and the communication load increases. That is, in the present embodiment, the communication load on the loop route does not differ in the route section. Therefore, the delay variation is reduced, and the relay delay time inside the relay terminals Ry1 to Ry7 can be made substantially equal.

  Moreover, in the present embodiment, since the L2SW path control is not performed, it is not necessary to set the communication path between the synchronous master-slave relay terminals Ry1 to Ry7 to be the same between the forward path and the return path, and the communication path changes. There is no change in communication delay time. Therefore, uniform synchronization accuracy can be obtained at each of the relay terminals Ry1 to Ry7, and stable sampling synchronization accuracy can be secured. Further, since the L2SW path control setting is not required, there is no possibility of an erroneous operation due to an erroneous setting, and the maintainability is improved.

  By the way, the transmission timing of the relay frame by the relay transmission unit 19 occurs asynchronously with the transmission timing of the electric quantity frame and the synchronization frame from the own station by the reception frame notification unit 20. Therefore, immediately before the relay transmission unit 19 starts the relay transmission, the transmission of the communication frame F of the own station may be in progress and the communication frame F may be damaged. Therefore, in the present embodiment, queues 16 and 17 are provided before the NICs 12 and 13 and transmission control is performed in order, thereby preventing the NICs 12 and 13 from being redundantly transmitted during transmission. Thereby, the damage of the communication frame F can be reliably prevented.

  Further, in the present embodiment, control is performed such that the electric quantity frame is not transmitted from the queues 16 and 17 during the period when the synchronization frame is staying in the queues 16 and 17. Therefore, it is possible to eliminate the contention competition between the synchronous frame relay and the transmission of the electric quantity frame. This makes it possible to keep the relay time constant.

  In the present embodiment, the relay necessity determination unit 18 determines that the relay is not performed if the destination MAC is addressed to the own station (based on the condition (A)). Is not distributed to other relay terminals. In addition, the relay necessity determination unit 18 determines that the relay is not performed if the source MAC is the local station (based on the condition (B)). Is not distributed to other relay terminals.

  Furthermore, if the relay TTL is equal to or more than the upper limit, the relay necessity determination unit 18 determines that the communication frame F is not relayed (based on the condition (C)), so that it is possible to prevent the illegal circulation of the communication frame F. When the relay TTL is 0, the relay necessity determining unit 18 determines that the communication frame F is not relayed (based on the condition (D)). There is no. As described above, in the present embodiment, by determining the necessity of the relay from the relay TTL of the communication frame F, it is possible to prevent the illegal loop of the damaged frame and to stabilize the consumption band of the communication line 2.

  Further, in the present embodiment, when an invalid frame occurs on the loop path due to a line failure such as a decrease in the optical level of the optical line or a momentary disconnection of the cable, the frame can be discarded based on the error detection by the FCS. . Further, the relay of these unauthorized communication frames can be suppressed by the TTL determination.

  In the present embodiment, if all devices such as various devices included in the two communication paths are sound, synchronous communication can be performed through the two communication paths, and a communication delay time and a synchronization error for two routes can be calculated. At this time, in this embodiment, since the variation of the communication delay time is smaller, the fluctuation of the synchronization error due to disturbance (communication load or the like) can be suppressed, and the synchronization accuracy can be further stabilized. It is.

  The received frame notification unit 20 stores the latest value of the transmission sequence number in the communication frame F and discards the communication frame F having the same transmission sequence number, that is, the communication frame F that arrives later. Don't worry about receiving. Therefore, the calculation unit 10 can perform accurate calculation processing.

  Further, in the communication frame F of the present embodiment, the relay TTL is arranged near the front of the user data area. Even when the determination is started, an accurate determination can be made. Therefore, according to the present embodiment, the relay time can be reduced, and even if a large number of relay terminals Ry1 to Ry7 are added to the loop path, it is possible to perform inter-station communication within the calculation cycle. Yes, it is possible to construct a system that reliably operates the relay process.

(2) Second embodiment (configuration and operation)
The second embodiment is a loop-type protection relay system in which n relay terminals Ry1 to Ryn are arranged at important points in a power system and connected in a loop by a communication line 2 as in the first embodiment. . FIG. 5 shows the configuration of the relay terminal Ry1, and the same reference numerals are given to the same components as those in the first embodiment in FIG. 2, and the description will be omitted.

  As shown in FIG. 5, the second embodiment is characterized in that the relay necessity determination unit 18 of the communication driver 11 is configured as independent dedicated hardware, and this is connected to general-purpose communication hardware. is there. An FPGA element 21 for relay control is mounted on independent hardware for determining relay necessity.

  The FPGA element 21 has a transmission waiting buffer 21a. The transmission waiting buffer 21a corresponds to the transmission waiting queues 16 and 17 in FIG. The FPGA element 21 has a relay condition table 21b. The relay condition table 21b is a table that holds the relay conditions set by the relay necessity determination unit 18 in FIG. Further, the FPGA element 21 has a relay determination unit 21c that determines whether or not to relay the communication frame F with reference to the relay condition table 21b.

  Hereinafter, the operation of each component of the FPGA element 21 will be described. The communication frame F received by the FPGA element 21 arrives at the relay determination unit 21c in the order of the destination MAC, the source MAC, and the type shown in FIG. The relay determination unit 21c can determine whether or not the relay of the communication frame F is necessary when the relay TLL is received from the information of the communication frame F. Therefore, in the received communication frame F, if relaying is required in accordance with the relay condition, the relay frame is sequentially stored in the transmission waiting buffer 21a of another route from the destination MAC.

  At this time, the FPGA element 21 performs the FCS calculation on the data stored in the transmission waiting buffer 21a, and subtracts 1 from the relay TLL before storing. When the electric quantity data is sequentially stored in the transmission waiting buffer 21a, the received FCS value is discarded, and the calculated FCS value is stored in the transmission waiting buffer 21a. The relay determination unit 21c distributes the information to the NICs 12 and 13 at the subsequent stage regardless of the necessity of the relay.

(effect)
In the first embodiment, since the relay process of the communication frame F is provided inside the communication driver 11, the relay is determined by the communication driver 11 based on the communication frame F received from the NICs 12, 13. A relay delay of at least a long frame time must occur.

  Therefore, in the second embodiment, by using the FPGA element 21 for relay control, relay determination is performed from the first n bytes of the received communication frame F, that is, cut-through relay is performed, thereby shortening the relay delay time. are doing. According to the second embodiment in which the relay delay time is reduced in this way, the inter-station communication delay time can be reduced, and a large number of stations can be added through the loop path.

  In the case of cut-through relay, there is a case where a corrupted frame of an FCS error is also relayed and distributed, which may cause a so-called broadcast storm. In the second embodiment, as in the first embodiment, the relay TLL is used to determine whether the frame is damaged. Relaying exceeding a certain number of times is suppressed. Therefore, the illegal frame does not circulate on the loop path, and there is no fear that a broadcast storm occurs.

  When the FCS error frame is delivered to the NICs 12 and 13 via the relay determination process, the NICs 12 and 13 detect and discard the FCS error. Therefore, it is possible to contribute to the construction of a stable system without the influence of device malfunction due to an illegal frame.

(3) Third Embodiment (Configuration and Function)
The configuration and operation of the third embodiment will be described with reference to FIG. The third embodiment is also a loop-type protection relay system in which n relay terminals Ry1 to Ryn are arranged at important points in a power system and connected in a loop by a communication line 2 as in the first embodiment. .

  As shown in FIG. 6, the feature of the third embodiment is that a relay control board 22 that functions as a relay necessity determination unit 18 is provided completely separate from a relay terminal. FIG. 6 shows a relay terminal Ry1, and the same components as those in the first embodiment shown in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.

  In the third embodiment, the relay necessity judging unit 18 is not dedicated hardware having the FPGA element 21 mounted thereon, but the communication driver 11 of the relay terminal Ry1 is general-purpose hardware as shown in FIG. The relay control board 22 is provided on the network side.

  The relay control board 22 has a transmission waiting buffer 22a, like the FPGA element 21 described above. The relay control board 22 has a relay condition setting SW 22b. The relay condition setting SW 22b obtains its own MAC by, for example, setting the relay TLL in the DIPSW setting or referring to the transmission source MAC of the transmission frame. Further, the relay control board 22 includes a relay determination unit 22c that determines whether or not to relay the communication frame F. Therefore, in the third embodiment, the same relay determination as in the second embodiment can be performed.

(effect)
According to the third embodiment, since the communication driver 11 of the relay terminal Ryn can be realized by general-purpose hardware, the communication driver 11 can be inexpensive and cost can be reduced. In the third embodiment, the relay control board 22 for performing the relay determination is provided independently of the relay terminal Ryn. Therefore, by adopting a high-performance board, higher-speed frame relay can be performed. This makes it possible to increase the reliability of the loop-type protection relay system.

(4) Fourth Embodiment (Configuration and Function)
In the communication frame F according to the fourth embodiment, as shown in FIG. 7, an information type is provided in a user data area. According to this information type, the communication frame F is distinguished into a diagnostic frame for diagnosing the state of the network and a normal relay processing frame. The terminal number and arrangement of each relay terminal Ryn that joins the loop path are set as management information in the diagnostic frame.

  The basic configuration of the fourth embodiment is the same as that of the second embodiment. That is, in the fourth embodiment, the relay necessity determination unit 18 of the communication driver 11 is provided as independent dedicated hardware, and the hardware includes the relay control FPGA element 21 and the general-purpose communication hardware. Connect to hardware.

  In the FPGA element 21 of the fourth embodiment, the relay determination unit 21c stores the received communication frame F in the received transmission buffer 21a on the root side if the information type of the communication frame F is a diagnostic frame. . As shown in FIG. 8, the relay determination unit 21c of the FPGA element 21 includes a connection configuration determination unit 23, a diagnostic frame return unit 24, and a relay terminal determination unit 25.

  As described above, the terminal number and arrangement of each of the relay terminals Ry1 to Ryn that join the loop path are set as management information in the diagnostic frame. For example, in the relay terminal Ry1 that has received the diagnostic frame, the diagnostic terminal The relay terminals Ry2 and Ry7 adjacent before and after are recognized by the transmission terminal numbers in the frame. Based on this recognition, the connection configuration determination unit 23 determines the soundness of the loop-like connection configuration of the communication line based on the diagnostic frame.

  If the information type of the received communication frame F is a diagnostic frame, the diagnostic frame returning unit 24 returns the diagnostic frame to the communication ports 8 and 9 that received the diagnostic frame via the transmission waiting buffer 21a. As a result, the diagnostic frame is looped back by the relay terminals Ry2 and Ry7 ahead of the transmitted route and arrives at the same route.

  The relay terminal determination unit 25 detects whether the diagnostic frame return unit 24 and the return of the diagnostic frame to the communication ports 8 and 9 have been received. Then, the relay terminal determination unit 25 determines the soundness of the relay terminals Ry2 and Ry7 connected before and after the relay terminal Ry1 based on the detection result.

(effect)
In the above-described fourth embodiment, the connection configuration determination unit 23 can determine the soundness of the loop-shaped connection configuration, and the relay terminal determination unit 25 can determine the health of each of the relay terminals Ry1 to Ry7. it can. Therefore, when a failure occurs in the loop communication path or each of the relay terminals Ry1 to Ry7, the failure location can be accurately estimated. In addition, since the soundness of both the loop communication path and the relay terminals Ry1 to Ryn can be determined, it is possible to determine a network connection error.

(5) Other Embodiments The embodiments described above are presented as examples in the present specification, and are not intended to limit the scope of the invention. That is, the present invention can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modified examples thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

  The number of relay terminals, the location in the power system, and the like can be changed as appropriate. Also, the configuration of the communication frame format and the like can be appropriately selected. For example, the initial value of the TTL may be set to (maximum number of terminals-1). By setting in this way, the communication frame broadcasted by the own relay terminal circulates and arrives on another route. Therefore, by using this for monitoring, it is possible to determine the soundness of the loop communication path.

8, 9 Communication port 10 Operation unit 11 Communication driver 12, 13 NIC
14 transmission processing unit 15 reception processing unit 16, 17 queue 18 relay necessity determination unit 19 relay transmission unit 20 reception frame notification unit 21 FPGA element 21a transmission waiting buffer 21b relay condition table 21c relay determination unit 22 relay control board 23 connection configuration Determination unit 24 diagnostic frame return unit 25 relay terminal determination units Ry1 to Ry7 relay terminal F communication frame

Claims (3)

A plurality of relay terminals for measuring electric quantity data are arranged in a power system, the relay terminals are connected in a loop without setting a loop end with a communication line, and a first communication frame including the electric quantity data is connected to another. In the loop-type protection relay system that shares the electric quantity data by distributing to the relay terminal,
Each relay terminal
Two communication ports,
A communication driver for transmitting and receiving the first communication frame to and from the other relay terminals;
An operation unit that performs a predetermined protection operation using the electric quantity data,
The communication driver,
Receiving the electric quantity data from the arithmetic unit, generating two first communication frames storing the same electric quantity data based on the electric quantity data, and from the two communication ports, before and after the connection. A transmission processing unit that transmits the same first communication frame to each of the relay terminals;
A reception processing unit that receives the first communication frame from each of the relay terminals before and after the connection via the two communication ports,
The reception processing unit,
On the basis of a predetermined condition, the first communication frame received through the communication port is transmitted to the communication port on the side opposite to the side that received the first communication frame. A relay necessity determination unit for determining whether to relay,
A relay sending unit that sends the first communication frame to the communication port when the relay necessity determination unit determines to relay the first communication frame;
Irrespective of a relay determination result of the relay necessity determination unit, a communication frame notification unit that notifies the first communication frame to the calculation unit ,
Each of the relay terminals performs synchronous communication in a second communication frame including synchronization control data at both of the two communication ports, and compares fluctuations in communication delay time in the synchronous communication at each of the communication ports, A loop characterized in that the synchronous communication of the communication port having the smaller communication delay time among the synchronous communication of the two communication ports is adopted as the synchronous communication by the line including the communication port. Type protection relay system.   The communication frame notification unit, when the first communication frame overlaps, notifies the operation unit of the first communication frame that arrives first, and discards the first communication frame that arrives last. The loop type protection relay system according to claim 1, wherein: Loop protection relay system as claimed in claim 1 or 2, characterized in that the relay constitutes a necessity determining section as independent hardware, and connect it to the universal communication hardware.

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