JP2011188644A - Protective relay device, control method for the same, control program for the same, and protective relay system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective relay device that transmits various types and a large amount of information to continuously maintain a protective function and achieve quick system protection response, a control method for the same, a control program for the same, and a protective relay system. <P>SOLUTION: The protective relay device has an electric-quantity acquiring part 160 for acquiring electric quantity data transmitted from a detection means provided in a power system, a communication interface for transmitting the electric quantity data via a communication network N, and a time holding part 143 for holding synchronous time. The electric quantity acquiring part 160 has a transmission-data generating part 162 for generating transmission data including electric quantity data sampled in a predetermined period and the sampling time. The communication interface has an Ethernet communication part 120 that uses the transmission data as an Ethernet communication frame. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a protection relay device for detecting an accident in a power system and separating a failure section, and more particularly to a protection relay device to which a high-speed network is applied, a control method and control program therefor, and a protection relay system.

  The current differential relay is disposed between power transmission line terminals for the purpose of power transmission line protection. This current differential relay can detect a system fault by calculating a current amount and a voltage amount (hereinafter referred to as an electric amount) at each terminal.

[Electricity calculation]
A typical example of the electric quantity calculation for detecting such a system fault is a current differential calculation. The current differential operation is an operation based on Kirchhoff's current law that the total amount of current flowing into and out of an arbitrary network is zero. In other words, based on detection values from instrument transformers installed at each terminal of the protection section, current differential relays connected to each measure current amount data and transmit them by communication. The sum of the current amounts is calculated.

  If the total amount of current is other than zero, the current differential relay determines that an accident has occurred within the protection section. The current differential relay that detects the accident outputs a control signal to a circuit breaker or the like so that the failure section is disconnected from the power system. Thus, the current differential relay is a type of protection relay device that performs power transmission line protection.

  In order to perform such electric quantity calculation, electric quantity data of each terminal is necessary. For this reason, each protection relay apparatus needs to measure the electric quantity data of its own terminal. And each protection relay apparatus is transmitting the measured electric quantity data of the own terminal to the protection relay apparatus arrange | positioned at the other terminal via the serial communication by a dedicated line.

  Here, in the electric quantity calculation, the measurement timing of the electric quantity at each terminal needs to be synchronized with high accuracy. This is called sampling synchronization. As a representative technique for realizing such sampling synchronization, an example of a technique applied to a current differential relay system is disclosed in Patent Document 1.

  In addition, the electric quantity calculation needs to be performed between electric quantity data of the same electric angle. For this reason, the protection relay device at each terminal adds a sampling address expressing the electrical angle at the time of measurement to the electrical quantity data measured by each terminal. And each protection relay apparatus is calculating using the data with the same sampling address with the electric quantity data which the self terminal measured, and the electric quantity data received from the other party terminal.

  The method of calculating the amount of electricity differs depending on the protection method. As for the electric quantity data used for the calculation, there are a method of calculating directly with an instantaneous electric amount, a method of calculating based on statistical results of the past n samplings, and the like. The present invention does not limit the specific calculation method to be applied, and therefore details thereof will be omitted.

[Timing synchronization]
In general, the measurement timing of the electric quantity and the counterpart communication are performed based on the system frequency. For example, in eastern Japan, it is carried out mainly at intervals of 30 degrees electrical angle of 50 Hz. In western Japan, it will be conducted at intervals of 30 degrees of 60Hz electrical angle. Then, the communication cycle of East Japan and the communication cycle of West Japan are as follows.

Communication cycle in East Japan: 1 / (50 Hz × (30 degrees / 360 degrees)) = 1.666 milliseconds Communication period in West Japan: 1 / (60 Hz × (30 degrees / 360 degrees)) = 1.388 milliseconds As described above, since the communication period (bandwidth) is different between East Japan and West Japan, the amount of data to be communicated and the data structure are different.

In the actual sampling synchronization method, the current differential relay is provided with the following functions in order to realize highly accurate synchronization.
・ Minimize fluctuations in delay time that occur in information frame communication.

A specific method for realizing this function is as follows.
・ Equipped with a mechanism to fix the frame transmission timing ・ Stabilization of transmission line delay time using a dedicated line ・ Equipped with a mechanism to maintain / acquire frame reception timing

[Oscilloscope function]
Further, as part of a protection system using a protection relay device, there is an oscilloscope function that collects electric quantity data. An oscilloscope for realizing the oscilloscope function is actually composed of an external device corresponding to a computer or a personal computer. Electric quantity data collection by the oscilloscope is performed by one of the following methods.

・ Reads the electrical quantity data in the protection relay device according to the command from the oscilloscope device. ・ Transmits the electrical quantity data from the protection relay device to the oscilloscope device at a specific cycle. Is called.

  The electrical quantity data handled by the protection relay device is processed data obtained by filtering unnecessary components via the analog input unit of the protection relay device. For this reason, depending on the purpose, some oscilloscopes have an analog input mechanism to collect raw electricity data.

  Further, the oscilloscope function includes a trend display of electricity quantity data transition and measurement control using the electricity quantity data. Since the present invention is not limited to any oscilloscope function, details are omitted.

[Data communication operation]
An example of the data communication operation in the conventional protection relay system as described above will be described with reference to FIGS. FIG. 14 is a configuration example of a two-terminal (a, b) protection relay system, and FIG. 15 is a configuration example of a three-terminal (a, b, c) protection relay system.

  The protection relay devices 400A to 400C of each terminal are connected via a serial transmission line La. Each of the protection relay devices 400A to 400C includes a protection control unit 410 that measures electric quantity data of its own terminal, and a serial transmission unit 420 that transmits electric quantity data.

  In such a protection relay system, an example of a frame configuration communicated between the protection relay devices 400A to 400C is shown in FIG. FIG. 16 shows an example of a 50 Hz communication frame format. In this communication frame format, one frame is 90 bits, and each of 12 bits of electric quantity data A to D is included.

An example of the development of the control bit (7 bits) is as shown in FIG. The meaning of each bit in FIG. 17 is as follows.
Synchronization control 1, 2: Used for sampling timing synchronization control. This is a value obtained by converting the sampling timing of the own terminal and the counterpart terminal into a count value.
Ready: Indicates the state of the end device. Used for defect detection status.
Controls 1, 2: Optional. Used for control commands and control status.
SA synchronization flag: Used for sampling address (SA) synchronization control.
Note that the contents of the control 1, control 2, and SA synchronization flags correspond to the frame numbers.

  Here, each of the protection relay devices 400A to 400C is set in advance as a master station / slave station. The slave station corrects the timing and synchronizes with the sampling timing of the master station. In the case of a configuration with a plurality of slave stations such as the three-terminal configuration shown in FIG. 15, the slave station 1 and the slave station 2 are arranged in order. In this case, after the slave station 1 synchronizes with the master station, synchronization is established in the order of the slave station 2 synchronizes with the slave station 1.

  When the establishment of the sampling synchronization is recognized, the sampling address synchronization between the terminals is established based on the SA synchronization flag (control bit b5 in FIG. 17). And it confirms that a system is sound by various monitorings, such as each synchronization establishment of a protection relay apparatus between terminals, and a transmission failure. After the confirmation, the protection relay device of each terminal performs system protection control based on the electric quantity data transmitted to each other and the electric quantity data measured at its own terminal.

  In the data communication directed to these counterpart terminals, a transmission path is arranged for each counterpart terminal as shown in FIG. Therefore, there is no reception destination (partner device address) information in the communication frame shown in FIG. Further, since the transmission path is individually installed for each counterpart terminal, the frame transmission process and the frame reception process are performed as many times as the counterpart terminal.

  The detailed technique of the sampling synchronization method and the synchronization establishment determination is omitted from Patent Document 1. Since the frame shown in FIG. 16 is transmitted at every sampling timing, there is no idle (no communication) time on the communication line.

  Further, in FIG. 15, an oscilloscope 430 is installed. The relationship between the oscilloscope 430 and the protection relay device 400B will be described. The oscilloscope 430 and the protection relay device 400B are connected by a dedicated communication line Lb. The protection relay device 400B is notified of a collection start command from the oscilloscope 430 via the dedicated communication line Lb.

  When the specified amount of electricity data is accumulated in the protection relay device 400B, the collection is completed. The collected data is transmitted to the oscilloscope 430 through the dedicated communication line Lb by the protection relay device 400B. The oscilloscope 430 performs trend display and measurement calculation based on the received collected data.

Japanese Patent Laid-Open No. 2-155421

RFC958 (Network Time Protocol)

By the way, the conventional protection relay device as described above has the following problems.
[Dedicated communication equipment is required]
In order to realize the communication method applied to the current differential relay of the prior art, a dedicated communication interface equipped with a special mechanism is required. The special mechanism is, for example, a mechanism for fixing frame transmission timing and holding / acquiring frame reception timing as described in the background art. Note that the communication interface here includes both hardware and software.

  The development cost of such a dedicated communication interface is higher than that of a general communication interface. In particular, with regard to hardware, there may be a case where parts and elements having low versatility have to be employed, and extra maintenance costs are required. Further, as described in the background art, since communication timing and communication data structure differ depending on the system frequency, development / maintenance of each software and hardware is required.

  Furthermore, data communication between the above-described protection system and the oscilloscope employs unique communication using a dedicated communication line. For this reason, it is necessary to mount a dedicated communication port and a communication function with the protection relay device in a computer or the like that realizes the oscilloscope device.

[Limit of communication data volume]
Due to restrictions on the specifications of communication equipment such as communication lines and relay equipment, the communication speed of current communication facilities is only 54 Kbps as a standard. In the example shown in FIG. 16, 1 frame length (90 bits) × 1 cycle (12 frames) × 50 Hz = 54000 (54 kbps).

  For this reason, the amount of electricity data that can be incorporated into one communication frame is very small. For example, it is assumed that the communication frame includes the electrical quantity data necessary for the current differential calculation, the data transmission cycle, and the communication frame defect test information (CRC code, fixed bit, etc.). Then, the electric quantity data of one communication frame becomes 3 to 4 quantities.

In order to cope with this, measures such as processing electric quantity data and optimizing the communication frame format for each protection system are being implemented. For example, the following is mentioned about processing of electric quantity data.
• Filter the measured electrical quantity data to compress the bit length. • Decompose / synthesize data that allows slow updates.

  However, the limit of the communication data amount as described above causes a further problem in data communication between terminals. One problem is that redundancy of communication data is difficult because a limited communication band must be used efficiently. Without redundancy, there is a possibility that the protection function will be affected even if a temporary communication failure occurs. For example, it is assumed that communication data is lost due to an instantaneous disturbance in a communication facility such as a communication line or a relay device. In such a case, if no redundancy is provided, the protection function is locked for several cycles required for recovery.

  Another problem is scalability of communication speed. In the current data communication as described above, 100% of the communication band is used. For this reason, the time required for collecting electric quantity data at each terminal is substantially fixed. Then, it becomes difficult to speed up the system protection response from the current level.

[GPS synchronization]
Note that a form using a high-speed multiplex line instead of communication using a dedicated line has been put into practical use. In this case, the problem due to the dedicated line as described above is eliminated. However, due to the multiplexing process of the communication frame, the frame transmission / reception timing is not stable, and it is difficult to adopt the conventional sampling synchronization control. In order to cope with this, as shown in FIG. 18, a GPS device is installed at each terminal of a current differential relay, and the sampling timing is adjusted by synchronizing each terminal with the GPS time.

However, this GPS synchronization has the following problems in terms of operation.
・ Because US military satellites are used, permanent use is not guaranteed. ・ It is necessary to secure an antenna installation place where radio wave reception is stable and stable. ・ The GPS device itself is expensive. ・ Radio waves from other devices are required. Unable to receive due to influence ・ Unable to receive due to intentional radio interference After all, in order to solve such problems, there are burdens and restrictions on operational, economic and stability.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and its purpose is to reduce development costs and maintenance costs without introducing a special mechanism or the like. It is an object of the present invention to provide a protection relay device, a control method and a control program therefor, and a protection relay system that can maintain a protection function continuously by enabling communication of various information and contribute to speeding up system protection response.

  In order to achieve the above object, the present invention includes an electric quantity acquisition unit that acquires electric quantity data from detection means provided in an electric power system, and a communication interface that communicates the electric quantity data via a communication network. A protection relay device having a time holding unit that holds a time synchronized with a time server (hereinafter referred to as a synchronization time), wherein the electric quantity acquisition unit includes electric quantity data acquired at a predetermined sampling period, A transmission data generation unit that generates transmission data including a sampling time extracted from the synchronization time at the sampling timing (which has the same function as the sampling address, hereinafter referred to as SA), and the communication interface It is characterized by having an Ethernet communication unit as an Ethernet communication frame. In addition, this invention can also be grasped | ascertained as a control method and control program for implement | achieving the function of each said part with a computer.

  In the present invention as described above, it is not necessary to adopt a special hardware mechanism by communicating the electrical quantity data with the sampling time added via Ethernet, and high-precision time synchronization is realized with a general-purpose processing configuration. it can. Equipment maintenance is also facilitated by using general-purpose network equipment and the environment. At the same time, since there is no dependence on the system frequency, the communication function can be shared regardless of the system frequency. Therefore, development costs and maintenance costs can be reduced.

  According to the present invention as described above, a special mechanism is not required, development costs and maintenance costs can be reduced, and a large amount of information can be communicated, so that the protection function can be continuously maintained.

It is a network block diagram which shows one Embodiment of the protection relay system of this invention. It is explanatory drawing which shows the Ethernet frame for communicating electrical quantity data in embodiment of FIG. It is explanatory drawing which shows the Ethernet frame which enables UDP / IP communication for communicating electric quantity data in embodiment of FIG. It is explanatory drawing which shows the NTP frame for communicating synchronous time in embodiment of FIG. It is explanatory drawing which shows the NTP message format of FIG. It is a functional block diagram which shows the protection relay apparatus in embodiment of FIG. It is a functional block diagram which shows the Ethernet communication part of FIG. It is a flowchart which shows the procedure of the time synchronization in embodiment of FIG. It is a flowchart which shows the transmission procedure of the electric quantity data in embodiment of FIG. It is explanatory drawing which shows the transmission timing of the conventional electric quantity data. It is explanatory drawing which shows the transmission timing of the electric quantity data in this embodiment. FIG. 12 is an explanatory diagram illustrating an example in which the same amount of electricity data is transmitted a plurality of times during the line idle period in FIG. 11. It is explanatory drawing which shows the example which performs a transmission process via the measurement data storage buffer in embodiment of FIG. It is a block diagram which shows an example of the conventional two-terminal protection relay system. It is a block diagram which shows an example of the conventional 3 terminal protection relay system. It is explanatory drawing which shows an example of the communication frame in the conventional protection relay system. It is explanatory drawing which shows the example of expansion | deployment of the control bit in the communication frame of FIG. It is a block diagram of the protection relay system which employ | adopted the conventional GPS synchronization.

A mode for carrying out the present invention will be described with reference to the drawings.
[1. Configuration of Embodiment]
[1-1. overall structure]
As shown in FIG. 1, the protection system according to the present embodiment is simply connected to the protection relay devices 100A, 100B, and 100C (hereinafter referred to as terminals if not distinguished from each other) via a LAN cable L or the like. 100), the time server 200, and the oscilloscope device 300. In the present embodiment, a three-terminal (a, b, c) configuration is adopted in which three terminals are used to detect the amount of electricity from detection means such as an instrument transformer installed in the transmission line W. However, the present invention is not limited to this.

  The protection relay device 100 and the oscilloscope 300 can be realized by controlling the function of each part by a predetermined program. The program in this case realizes the functions of each unit described below by physically utilizing the hardware of the computer, and the program and the recording medium on which the program is recorded are independent of one another of the present invention. It is an aspect. In addition, a database necessary for communication and data processing, storage of set values such as a predetermined cycle, a buffer for temporarily storing data, frames, and the like are realized in a storage unit set in the computer. As the storage unit, any storage medium such as a memory or a disk that can be used now or in the future can be applied.

[1-2. Communication network]
As the communication network N, Ethernet (registered trademark) is used. Ethernet is a network standard that defines physical layer and data link layer processing in the ISO reference model. This standard is currently used in many LANs, MANs and WANs, regardless of their size. Ethernet is a standard that is almost the same as IEEE 802.3 and its extended functions. In the present invention, both may be regarded as synonymous.

  Note that the Ethernet communication speed applied to the communication network N does not matter. However, if high-speed communication such as Gigabit Ethernet is employed, transmission delay is small, high synchronization accuracy can be ensured, and larger-capacity communication data can be transmitted and received.

[1-3. Communication frame]
A frame format for communicating via the communication network N will be described with reference to FIGS. First, a frame format having a structure according to the Ethernet frame will be described with reference to FIG. That is, this frame has a destination address field (6 bytes), a source address field (6 bytes), and a type field (2 bytes) which are Ethernet headers.

  The Ethernet header is added to the SA (sampling address) field (8 bytes) and the data field (38 to 1492 bytes) together with the FCS (frame check sequence) field (4 bytes) to form a communication frame.

In the destination address field, the destination MAC address of the frame is entered. The source MAC address of the frame is entered in the source address. The type field generally contains a type number indicating the type of the upper layer protocol of the Ethernet layer. Typical type numbers are as follows:
・ IPV4: 0800
ARP: 0806
-SNMP: 814C
NetBIPS: 8191

  However, in the case of a frame for communicating electrical quantity data according to the present embodiment, a type number for distinguishing from other frames is entered. Specifically, a number other than the protocol type number already determined as described above is assigned. Alternatively, a protocol type number that is not used in the network is assigned.

  A sampling address (SA) is entered in the SA field. This SA expresses the time (sampling timing) when the electric quantity data is measured. The actual SA has the same structure as the time stamp of the time synchronization protocol (NTP: Network Time Protocol) (see FIGS. 4 and 5). Thereby, SA becomes an index for the purpose of data tuning when performing a differential operation between the measured electricity quantity data of its own terminal and the received electricity quantity data from the counterpart terminal. It is necessary to synchronize the SA of each terminal before starting the differential operation.

  The data field is a field in which terminal data is entered. The terminal data includes electric quantity data (current quantity, voltage quantity, etc.) measured at its own terminal and arbitrary attached information such as the control / monitoring status of the apparatus. The electric quantity data has different information types and bit lengths depending on the protection interval and method. Since the value of this data field is not limited to a specific format, description of data details is omitted. The amount of information that can be communicated as a data field is obtained by subtracting the necessary information size other than the electrical quantity data (38 to 1492 bytes) from 64 to 1518 bytes, which is the effective size of the entire Ethernet frame.

  FIG. 3 shows a frame structure when electric quantity data is communicated by UDP / IP. In this case, the length of the data field is shortened by 10 to 1464 bytes by the IP header field (20 bytes) and the UDP header field (8 bytes). The IP header field contains a destination IP address, a source IP address, an IP field size, and the like. The UDP header field contains a destination port number, a source port number, a UDP field size, and the like.

  As described above, by performing communication using UDP / IP, transmission / reception based on IP address + port number recognition instead of MAC address recognition becomes possible. In addition, since the checksum test of the received frame is performed in the IP layer and the UDP layer, the reliability of the received electric quantity data is improved.

  Further, even when a dedicated code (type number) cannot be incorporated in the type field as shown in FIG. 2, it can be easily handled by communicating with UDP / IP. The reason why the dedicated code cannot be applied to the type field is the software and hardware configuration that realizes the communication function. This is due to the following reason.

  It is the data link layer that generates the Ethernet frame (generation / addition of the Ethernet header and FCS). If the processing in the data link layer is within the range of program design / manufacturing including software processing, it is easy to set the value written to the type field as an arbitrary value. However, when the general-purpose packaged TCP / IP interface function is used as a software configuration (for example, Windows interface Windowsock installed in Windows (registered trademark) which is the OS of a personal computer), the data link layer is used. It is difficult to operate arbitrarily.

  There is also a network LSI chip in which a TCP / IP protocol stack is incorporated. In this case, the user data section is the only area that can be opened as a software interface. Therefore, all operations of the data link layer are performed inside the network LSI and cannot be accessed from software.

  Therefore, even when a dedicated code cannot be incorporated in the type field as described above, it is possible to easily cope with communication by UDP / IP. However, since the overhead of UDP / IP processing is added in the frame transmission / reception processing, the processing load is lower when the Ethernet frame is adopted. TCP / IP is not suitable for real-time control communication such as a protection relay because it has timed management such as delivery confirmation and recovery processing.

  In addition, FIGS. 4 and 5 show frame formats of a time synchronization protocol (NTP) applied to time synchronization between terminals. In FIG. 5, the upper 32 bits of the time stamp means the second time, and the lower 32 bits means the nanosecond time. Note that the NTP technique including the frame structure is a known technique disclosed in Non-Patent Document 1 and the like. Further, the present invention is not limited to a specific time synchronization method. Therefore, detailed description is omitted.

[1-4. Protection relay device]
As shown in FIG. 6, the protection relay device 100 includes a protection control unit 110, an Ethernet communication unit 120, and the like.

[1-4-1. Ether Communications Department]
The Ethernet communication unit 120 includes an Ethernet communication driver 121, a general-purpose network control circuit 122, and the like. As shown in FIG. 7, the Ethernet communication driver 121 includes a transmission processing unit 123, a reception processing unit 124, and the like. The general-purpose network control circuit 122 includes a transmission buffer memory 125, a reception buffer memory 126, a network interface controller (NIC) 127, a connector (RJ45) 128, and the like. The NIC 127 includes a MAC layer control circuit 127a, a physical layer control circuit 127b, and the like.

  Such an Ethernet communication unit 120 is a means for performing communication processing at the physical layer and MAC layer level, such as signal conversion, determination of a frame addressed to its own terminal, addition of an Ethernet header, etc., by the configuration as described above. Since it is a well-known technique, description is abbreviate | omitted.

[1-4-2. Protection control unit]
As shown in FIG. 6, the protection control unit 110 includes a protocol processing unit 130, a time acquisition unit 140, a sampling pulse oscillation circuit 150, an electric quantity acquisition unit 160, a control calculation unit 170, and the like.

  The protocol processing unit 130 is a unit that performs higher-level protocol processing than the Ethernet communication unit 120, and transfers frames to the Ethernet communication unit 120. The protocol processing unit 130 includes a UDP / IP processing unit 131, an NTP processing unit 132, and the like. The UDP / IP processing unit 131 is means for adding a UDP / IP header to transmission data, checking a UDP / IP header of a received frame, outputting received data, and the like.

  The NTP processing unit 132 is means for synchronizing time by processing NTP data. The NTP processing unit 132 includes a request unit 132a, an extraction unit 132b, and the like. The request unit 132a is means for performing time synchronization request processing for the time server 200 at a predetermined timing (polling interval). The extraction unit 132b is means for extracting a time stamp and the like necessary for synchronization from the NTP data of the received frame.

  The sampling pulse oscillation circuit 150 is a circuit that oscillates a sampling pulse at a predetermined cycle. The time acquisition unit 140 is a timer counter having a counting unit 141, a time holding unit 142, a calculation unit 143, and the like. The count unit 141 is a means for counting according to the sampling pulse. The time holding unit 142 is means for holding an internal time (for example, in microsecond units), and the internal time is a synchronization time obtained by a time synchronization protocol with a time server. The calculation unit 143 is a unit that performs operations such as unit conversion of the time stamp to the internal time and addition of the time according to the count to the internal time.

  The electric quantity acquisition unit 160 is means for acquiring electric quantity data output from an instrument transformer or the like of its own terminal. The electricity quantity acquisition unit 160 includes an A / D conversion unit 161, a transmission data generation unit 162, an activation processing unit 163, a transmission data holding unit 164, and the like. The A / D converter 161 is means for converting analog electrical quantity data into digital.

  The transmission data generation unit 162 is a unit that generates transmission data by adding the SA acquired from the time holding unit 142 to the electrical quantity data acquired from the A / D conversion unit 161. The transmission data holding unit 164 is means for holding the transmission data generated by the transmission data generation unit 162. The activation processing unit 163 is a unit that controls the acquisition timing of the electric quantity data by starting the electric quantity acquisition unit 160 at a predetermined period corresponding to the sampling pulse.

  The control calculation unit 170 is a means for outputting a control signal to the circuit breaker or the like according to the electric quantity calculation. The control calculation unit 170 includes an electric quantity calculation unit 171, a determination unit 172, and a control signal output unit 173. The electric quantity calculation unit 171 is means for performing an electric quantity calculation based on the received electric quantity data of the other terminal and the electric quantity data of the own terminal. The determination unit 172 is means for determining an abnormality such as an accident based on the calculation result of the electric quantity calculation unit. The control signal output unit 173 is means for outputting a control signal according to the determination result.

[1-5. Time server]
The time server 200 is installed for the purpose of tuning electric quantity data at the time of calculation. This is because the terminals are far apart in distance and the transmission delay time cannot be ignored. Note that, as in the sampling synchronization method employed in the conventional current differential relay, the electrical quantity data tuning may be performed by obtaining the transmission delay time from the measurement of the time required for frame communication round-trip. In this case, the time server becomes unnecessary.

[1-6. Oscilloscope]
The oscilloscope 300 is a device that collects, analyzes, etc. electric quantity data. As the oscilloscope 300 itself, a well-known device can be applied, and a description thereof will be omitted.

[2. Operation of the embodiment]
[2-1. Overview of operation]
The data communication operation according to the present embodiment will be described with reference to the flowcharts of FIGS. 8 and 9 and the explanatory diagrams of FIGS. In addition, there is no master-slave setting in the protection relay devices 100A to 100C of each terminal, and each protection relay device 100A to 100C performs the time synchronization by the network synchronization protocol with the time server 200 from the start, so that each internal Times are synchronized. In addition, the sampling time extracted from the synchronization time obtained by synchronization is added to the electrical quantity data as SA, and is transmitted and received between the protection relay devices 100A to 100C of each terminal. Thereby, accurate electric quantity calculation becomes possible.

[2-2. Time synchronization]
The procedure of time synchronization in this embodiment will be described with reference to FIG. That is, the request unit 132a of the NTP processing unit 132 outputs a time synchronization request packet at a timing according to a predetermined polling interval (steps 801 and 802). This request packet is transmitted to the time server 200 by the Ethernet communication unit 120. The NTP frame including the response packet generated and transmitted by the time server 200 is received by the Ethernet communication unit 120 (step 803). From the received NTP frame, the time stamp in the response packet is extracted by the extraction unit 132b in the NTP processing unit 132 through the UDP / IP processing unit 131 (step 804).

  The calculation unit 143 in the time acquisition unit 140 performs unit conversion of the acquired time stamp and holds (updates) the internal time of the time holding unit 142 (step 805). The calculation unit 143 updates the internal time of the time holding unit 142 by adding the sampling period (time width) of the sampling pulse oscillation circuit 150 for each count by the counting unit 141.

[2-3. Electric quantity data measurement]
The activation processing unit 163 acquires the electric quantity data by starting the electric quantity acquisition unit 160 at a predetermined cycle based on the pulse oscillated by the sampling pulse oscillation circuit 150 (steps 901 and 902). At this time, since the measurement information such as the current amount and the voltage amount is analog data, it is converted into digital data by the A / D converter so that it can be processed by software.

  The transmission data generation unit 162 adopts the internal time held in the time holding unit 142 as the SA of the acquired electric quantity data (step 903). The electric quantity data to which SA is added is held in the transmission data holding unit 164. A / D conversion is performed by operating a series of operations such as extraction of analog data and data filter in units of internal clocks. Due to recent advances in clock speed and device density, faster A / D conversion has been realized, and the electrical quantity data for a finer electrical angle can be extracted by shortening the electrical quantity acquisition cycle. It becomes possible to do.

[2-4. Frame transmission / reception processing]
Based on the transmission data generated as described above, a transmission frame is generated by the Ethernet communication unit 120 (step 904) and transmitted to the protection relay devices 100B and 100C (step 905). When transmitting by UDP / IP, the UDP / IP processing unit 132 adds a UDP header to the transmission frame.

  Here, as shown in FIG. 1, all the protection relay devices 100 </ b> A to 100 </ b> C are connected to one Ethernet communication network N. As shown in FIGS. 2 and 3, a destination address, a type number, and the like are added inside the communication frame. For this reason, in the Ethernet communication unit 120, it is possible to determine whether or not the frame received by each of the protection relay devices 100A to 100C is a reception frame (electric amount data) that is valid at its own terminal.

  In addition, the frame reception process is performed for the number of counterpart terminals as in the conventional protection relay device. However, the frame transmission process can be distributed to all counterpart terminals in a single frame transmission process by broadcasting the multicast address or broadcast address based on the destination address. The electrical quantity data of each terminal is also transmitted to the oscilloscope 300 connected to the same communication network N. For this reason, in the oscilloscope 300, it is possible to collect and analyze the electric quantity data distributed in the same broadcast without instructing the protection relay.

  Whether to use multicast or broadcast differs depending on the network configuration. That is, when a plurality of protection relay devices 100 with different protection intervals are connected on one network, multicast distribution is performed. Thereby, a communication frame can be prevented from being distributed to the protection relay device 100 in another protection section. Broadcast distribution may be used as long as the communication network N is closed in one protection section.

[2-5. Communication bandwidth]
In this embodiment, since Ethernet is used as the communication network N, the communication band is very large compared to the conventional serial communication speed of 54 Kbps. For example, if the communication speed of Ethernet is 100 Mbps, it is about 1800 times the conventional speed, and if it is 1 Gbps, it is about 18000 times the conventional speed. As a result, the idle period of the communication line is greatly increased, so that it is possible to transmit the electric quantity data or the like during this period.

  This will be described with reference to FIGS. 10 to 13 from the relationship between the electrical quantity measurement process and the data transmission process. First, FIG. 10 shows the relationship between the electrical quantity measurement (acquisition) processing and the transmission frame transmission processing by the protection relay devices 400A to 400C (see FIGS. 14 and 15) employing the conventional 54 Kbps line. The horizontal axis in FIG. 10 is the elapsed time. The measurement timing is about 1.666 milliseconds with an electrical angle interval of 30 ° in terms of a system frequency of 50 Hz.

  In each of the protection relays 400 </ b> A to 400 </ b> C, the serial transmission unit 420 generates a transmission frame based on the electrical quantity data acquired by the protection control unit 410 and sends it to the communication line L. In this case, since 90-bit data that can be communicated in the transmission band of 54 Kbps is one transmission frame, there is no line idle period. For this reason, one transmission process is performed per measurement process.

Next, FIG. 11 shows the relationship between the measurement process and the transmission process when the communication speed is 100 Mbps, the communication data amount is increased, and one data amount is converted to 1 kbyte in this embodiment. The measurement timing is about 1.666 milliseconds with an electrical angle interval of 30 ° in terms of a system frequency of 50 Hz. As is clear from FIG. 11, according to the present embodiment, it can be seen that the line idle period can be largely secured as follows, as compared with the prior art of FIG.
・ Transmission time = 1/100 Mbps × 8 bits × 1 kbyte = 80 μsec ・ Line idle period = 1666 μsec−80 μsec = 1586 μsec (during electrical angle of 30 °)

  Further, FIG. 12 shows an example in which redundancy is achieved by continuously transmitting the same frame (SA is the same frame as the previous transmission) with the electricity quantity data transmitted last time during the line idle period of FIG. . Here, the idle time is provided between successive transmissions in order to suppress congestion caused by overlapping frame transmissions from other terminals and other devices on the communication network and the accompanying transmission delay fluctuation. In particular, in a case where a HUB such as a switch or a repeater intervenes in the network as a relay device, a plurality of frames cannot be relayed at a time, resulting in a relay waiting time. Here, the relay waiting time can be minimized by increasing the frame transmission interval. Further, by minimizing the transmission delay variation, more accurate time synchronization is achieved.

[2-6. Separation of operation timing]
Since the sampling time (SA) is added at the time of generating the electric quantity data frame, it is not always necessary to transmit in synchronization with the sampling period. The operation timing of measurement processing and transmission data generation, and the mode of transmission processing timing will be described with reference to FIG. In this aspect, the measurement process and the transmission data generation process are executed at intervals of an electrical angle of 5 degrees, and the latest transmission data is stored in the transmission data storage unit 164. In the transmission process, the latest transmission data stored in the transmission data storage unit 164 is extracted and transmitted at an electrical angle of 2.5 degrees.

  Thus, each operation cycle can be arbitrarily set by eliminating the dependency between the operation timing of the measurement processing and the transmission data generation processing and the operation timing of the transmission processing. Thereby, in the transmission process, redundant communication that fully utilizes the network communication band can be performed. In addition, it is possible to flexibly cope with an increase in the operation cycle of the measurement processing unit, and it is possible to instantly notify a counterpart terminal of a minute change in electrical quantity data.

[2-7. Electricity calculation]
In each of the protection relay devices 100A to 100C, it can be confirmed that the system is sound by various monitoring such as establishment of time synchronization and transmission failure. After confirming in this way, the control calculation unit 170 in the protection relay devices 100A to 100C of each terminal implements system protection control based on the electrical quantity data transmitted to each other and the electrical quantity data measured at its own end. .

  That is, the electric quantity calculation unit 171 performs electric quantity calculation based on the received electric quantity data and the electric quantity data of its own terminal. This is intended for electric quantity data with the same SA. The determination unit 172 determines abnormality based on the calculation result. The control signal output unit 173 outputs a control signal according to the determination result by the determination unit 172.

[3. Effects of the embodiment]
According to the present embodiment as described above, it is not necessary to employ a special hardware mechanism, and software processing can be performed with a general-purpose processing configuration such as Ethernet communication or UDP / IP communication, and accurate time synchronization can be realized. Equipment maintenance is also facilitated by using general-purpose network equipment and the environment. At the same time, since there is no dependence on the system frequency, both hardware and software can share the communication function regardless of the system frequency. Therefore, development costs and maintenance costs can be reduced.

  In addition, since the communication band is greatly expanded, a great amount of electricity information and device information can be communicated to the counterpart terminal. This makes it possible to construct various protection control systems.

  Also, redundancy can be achieved by continuously transmitting the electricity quantity data transmitted last time using the line idle period. Therefore, even if there is data loss due to a single communication failure, it can be interpolated with the electric quantity data transmitted next. For this reason, it is possible to maintain the protection function continuously.

  Further, the transmission interval of the electric quantity data and the time for one frame communication are greatly shortened as compared with the conventional case. As a result, the time required for collecting the electric quantity data of all terminals is shortened, and the data communication of minute electric quantity fluctuations is possible. Therefore, it contributes to speeding up the system protection response.

  In addition, the oscilloscope device in the communication network can capture the electrical quantity data transmission frame exchanged between the terminals. For this reason, it is not necessary to install a dedicated communication line between the oscilloscope and the protection relay device. Therefore, both hardware and software functions can be reduced. In addition, product costs and software performance can be improved.

  Further, the oscilloscope device can be placed regardless of the location as long as it can be accessed on the communication network. For this reason, it becomes easy to construct a portable type oscilloscope device (by using a wireless LAN or the like). Furthermore, it is possible to improve the reliability of the oscilloscope function by simplifying the installation multiplexing.

[4. Other Embodiments]
The present invention is not limited to the above embodiment. For example, the specific contents and values of each information used in the present invention are free and are not limited to specific contents and numerical values. For example, the information included in the terminal data is not limited to that exemplified in the above embodiment. The protocol type and operation timing of time synchronization and the transmission timing of electric quantity data can also be set freely.

  A part or all of the protective relay device can be configured as a dedicated circuit. Such a circuit may be variously conceived, for example, an IC chip such as an ASIC or CPU that realizes each function, other peripheral circuits, a system LSI that integrates a plurality of functions, and is not limited to a specific one. The scope of hardware processing and software processing is also free.

100A to 100C, 400A to 400C ... protection relay devices 110, 410 ... protection control unit 120 ... Ethernet communication unit 121 ... Ethernet communication driver 122 ... general-purpose network control circuit 123 ... transmission processing unit 124 ... reception processing unit 125 ... transmission buffer memory 126 ... Reception buffer memory 127 ... NIC
127a ... MAC layer control circuit 127b ... physical layer control circuit 128 ... connector 130 ... protocol processing unit 131 ... UDP / IP processing unit 132 ... NTP processing unit 132a ... requesting unit 132b ... extraction unit 140 ... time acquisition unit 141 ... counting unit 142 ... Time holding unit 143 ... Calculating unit 150 ... Sampling pulse oscillation circuit 160 ... Electrical quantity acquisition unit 162 ... Transmission data generation unit 163 ... Startup processing unit 164 ... Transmission data holding unit 170 ... Control calculation unit 171 ... Electric quantity calculation unit 172 ... Determination unit 173 ... control signal output unit 200 ... time servers 300, 430 ... oscilloscope 420 ... serial transmission unit

Claims (8)

In a protection relay device having an electric quantity acquisition unit for acquiring electric quantity data from a detecting means provided in an electric power system, and a communication interface for communicating the electric quantity data via a communication network,
A time holding unit for holding the synchronization time;
The electrical quantity acquisition unit includes a transmission data generation unit that generates transmission data including electrical quantity data sampled at a predetermined period and the sampling time,
The communication interface includes an Ethernet communication unit that uses the transmission data as an Ethernet communication frame.   The protection relay device according to claim 1, further comprising an oscillating unit for oscillating a sampling pulse serving as a reference of the predetermined period.   The protection relay device according to claim 1, further comprising a protocol processing unit that synchronizes the synchronization time in the time holding unit via the communication network with a time synchronization protocol.   The protection relay device according to any one of claims 1 to 3, wherein the communication interface is provided so that communication frames of the same electrical quantity data can be continuously transmitted during line idle. . A computer or an electronic circuit has an electric quantity acquisition unit and a communication interface, the electric quantity acquisition unit acquires electric quantity data from detection means provided in a power system, and the communication interface receives the electric quantity data. In a control method of a protection relay device that communicates via a communication network,
The computer or electronic circuit has a time holding unit,
The electric quantity acquisition unit generates transmission data including electric quantity data sampled at a predetermined cycle and the sampling time,
The method of controlling a protection relay device, wherein the communication interface uses the transmission data as an Ethernet communication frame. In a control program for a protection relay device that causes a computer to acquire electric quantity data from detection means provided in an electric power system and to communicate the electric quantity data via a communication network,
In the computer,
Keep sync time,
Generate transmission data including electricity quantity data sampled at a predetermined period and the sampling time,
A control program for a protection relay device, wherein the transmission data is generated as an Ethernet communication frame.   A protection relay system, wherein the plurality of protection relay devices are connected to an Ethernet communication network.   The protection relay system according to claim 7, wherein an oscilloscope device that receives a communication frame communicated by the protection relay device is connected to the communication network.

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