0 Introduction With the rapid development of Jiangsu power grid and the increasing demand for power system applications, the demand for information in the system has increased significantly. The original telecontrol communication method has been difficult to meet the requirements of practical applications. Due to the large number of 220kV substations in Jiangsu Power Grid, a large number of CDT protocols have been used to transfer information from provinces to provinces. The original design of the CDT protocol is to minimize the occupation of transmission bandwidth and reduce the processing difficulty of both transmission parties to adapt to the limited communication and computer resources in the past. However, the following problems exist: 1 The information capacity is limited. The information word length of the CDT protocol is only 6 bytes, of which 5 bytes directly carry address information and data information, resulting in a very limited address space that can be supported, and can not meet the needs of large-scale deployment of data transfer. At present, we often use the method of adding channels to increase the capacity. Two or more ports are needed to save information transmission. There are also four or more dedicated remote channels and the performance-cost ratio is extremely low. 2 Single data type. The limited information capacity makes the CDT protocol only represent 3 data types: binary, 16-bit analog, and 32-bit cumulative. 3 Slow response. Most of the traditional telecontrol channels use communication rates of 9600 bits/s or less (even 300 bits/s to 600 bits/s). The data refresh is slow, and the update data is not updated in time. The real-time performance cannot meet the system requirements. 4 poor reliability. The event delivery mechanism of the CDT protocol increases the probability of correct acceptance by the opposite side by issuing duplicate messages. Since no more scientific response confirmation method is used, the interfered message may be lost, and reliable transmission of event information cannot be ensured.
Therefore, the use of more advanced communication means to transform the original telecontrol communication method is very necessary. With the completion and deployment of the Jiangsu Power Data Network, Jiangsu Province has conducted research and application of EMS network communications.
1 Telecontrol Communication Networking 1.1 Selection of Network Technology Although telecontrol communication requires high real-time performance, with the advancement of network technology, it is now possible to obtain the required network speed at a reasonable cost. For networks within the EMS and within the substation, Fast Ethernet based on switching technology is undoubtedly the best choice. At the 10 Mbit/s level, Ethernet may also have competitors, such as token ring networks. However, after entering the rate of 100Mbit/s and higher, Ethernet is the first choice in the LAN field regardless of performance or price. Other high-speed network technologies, such as ATM and FDDI, although not widely used in local area networks, can be used as a wide area network solution for connecting a master station to a master station, a master station, and a substation.
1.2 Transport Layer Protocol and Routing Function Due to the great success of the Internet, TCP/IP has become the de facto standard from the LAN to the WAN. TCP/IP uses IP to complete routing and TCP to implement transport layer control. Both functions and efficiency can meet the needs of telecontrol communication. Due to its extensive use on the Internet, it has led to the development and production of a large number of TCP/IP-based hardware and software worldwide. It can be said that TCP/IP is currently the most widely supported, fastest-growing and most mature network protocol. Therefore, IEC also selected TCP/IP as the basic protocol of IEC60870-5-104 and TASE.2.
1.3 Choice of application layer protocol With TCP for transmission control, in principle, any application layer protocol can be selected. Taking into account the interoperability between different systems, in order to make the system has a better openness and scalability, should be selected in the international standard agreement. Currently selected and possibly selected protocols in the future include: IEC60870-5-101, IEC60870-5-104, IEC60870-6 (TASE.2), IEC61850. The basic characteristics of these application layer protocols are shown in Table 1.
From Table 1, we can see that in addition to IEC60870-5-101, the other three protocols are designed for use in a network environment. IEC60870-5-101 uses variable-length addresses, up to a maximum of 24 bits, to meet the needs of data transmission between substations, substations and primary stations. Therefore, IEC 60870-5-101 is the best alternative to the traditional telecontrol protocol when it is impossible to carry out network transformation. The TASE.2 and IEC 61850 protocols go one step further by changing the way data (device) is positioned to be retrieved by name, giving them nearly unlimited data capacity, giving greater flexibility to upper-layer applications. IEC 61850 even supports hierarchical naming, providing better information integration capabilities for EMS developed in accordance with the IEC 61970 specification.
2 application layer protocol in the EMS application According to the characteristics of different protocols and their current use in the EMS, you can get the following conclusions:
a. From the application requirements and the attitude of the IEC, it can be seen that the telecontrol communication network is the trend of the times, and it is a wise choice to gradually carry out network transformation.
b. The standardization, standardization, and object-oriented development of EMS are development trends, and new protocols with object-oriented features can be selected on the premise of conditions permitting. This is a step-by-step process from the top to the bottom and from the main station system to the substation system.
c. TASE. Both IEC 61850 and IEC 61850 originated from the research and promotion of UCA (Utility Communication Architecture) by China Electric Power Research Institute (EPRl). They are based on another protocol ISO 9506 (Manufacturing Message Specification) and use the services provided by MMS. From Table 1, it can be seen that IEC recommends that IEC 61850, IEC 60870-5 and IEC 60870-6 be selected for use in different situations. Although IEC 61850 is not finalized at present, it can be guaranteed that the investment in TASE.2 will not be wasted due to the promotion of IEC 61850. .
Based on the above analysis, we determine the following principles:
a. Establishes network communication between the master station and the master station and selects TASE.2;
b. Network communication between the main station and substation and use IEC60870-5-104;
c. For the local monitoring system is relatively simple or there is no local monitoring of the RTU device to achieve network communication by IEC60870-5-104;
d. For RTU devices that do not have network capabilities, use the terminal server to connect to the Internet or directly use the serial channel, and then use IEC60870-5-101. The terminal server mode is recommended.
3 Jiangsu power data network construction In order to solve the problems existing in traditional telecontrol communication, the application work of EMS network communication must first be complete data communication network. In 2000, the Jiangsu Provincial Electric Power Company established a three-level ATM-based data network, which is divided into a backbone exchange layer and an access layer. The backbone switching layer includes the headquarters of the Jiangsu Electric Power Company and all 13 regional power supply companies. The Northland Telecom Passport 15000 is used as the backbone ATM switching device. The switching capacity is 40 GB, the trunk bandwidth is 622 Mbit/s, and the Passport 7480 is selected as the backbone node service access device. The contact layer includes 500kV substations and major power plants in Jiangsu Power Grid, and selects Northern Telecom Passport 5430. It uses the 2Mbit/s ATM trunk to access nearby backbone nodes according to the principle of nearest access. During the implementation of IP services, Jiangsu Power Data Network built a VPN for real-time control services using the IP VPN function provided by the Northern Telecom Passport Switch (referred to as real-time VPN). The real-time scheduling system for each node directly accesses the real-time data through the network communication workstation. VPN, adopts IEC60870-6TASE.2 agreement to carry on the real-time data communication between the province, the ground adjustment EMS/SCADA system. The work of directly accessing the RTU information of the provincial power plants and 500kV substations via the Internet is currently under way.
4 The use of communication protocol in the Jiangsu Power Grid EMS The application of the Jiangsu Power Grid EMS data network communication is divided into the following three aspects: 1 to adjust the inter- provincial TASE.2 communication; 2 between the power plant or substation and provincial transfer IEC60870-5 -104 Network communications; 3 Power plants or substations communicate through conventional telecontrol protocols between terminal servers and provincial transmissions. The schematic diagram of the three communication methods is shown in Figure 1.
Select TASE.2 communication between the local tone and provincial tone. Jiangsu Province and Nanrui Power Grid Control Co., Ltd. carried out cooperative development on the OPEN2000 system. At present, most TES.2 communications are carried out with provincial transmission. Among them, Suzhou, Nanjing, Yangzhou, Xuzhou, and other power supply companies TASE.2 have been officially put into operation, and conventional telecontrol communication has been canceled and achieved good results. running result. The information capacity is no longer limited. In addition to the breakers in the substations, the remote signaling information also sends the required barrier information to the province. At the same time, the real-time nature of the system has been reliably ensured. After testing, the artificial remote-reconversion or remote-sensing abrupt change from the ground tone to the time adjustment of the main line diagram reaction time is less than 5 seconds and the remote signal is less than 4 seconds. Therefore, TASE.2 communication has been well applied in Jiangsu Power Grid and has produced huge benefits.
IEC60870-5-104 communication is used between power plants or substations and provincial transmissions. At present, Jiangsu Power Grid adopts the IEC60870-5-04 network communication protocol and has put into operation five power stations, namely Sheyang Port, Xiagang, Yancheng, Xutang, and Shubi, and Dongshan Bridge 500kV substation. The information transmission effect is very good. The on-site telemetry and remote signal change to the main station main wiring diagram reaction time, the telemetry is less than 4s, the remote signal is less than 3s, and when using the conventional telecontrol communication method, the response time is greater than 10s.
Power plants or substations communicate through conventional telecontrol protocols between terminal servers and provincial transmissions. As can be seen from Figure 1, this communication only uses network transmission, its application layer protocol or conventional telecontrol protocol, the true transmission rate is limited by the RTU serial port rate. However, due to the omission of modem equipment at both ends, its bit error rate is greatly reduced, and the reliability of the communication channel has been greatly improved. Currently, only one Shimonoseki power plant is put into operation by Jiangsu Power Grid in this way, and the effect is relatively good. The adoption of this communication method will greatly increase the reliability of information transmission and is more suitable for smaller power plants or substations.
Judging from the experience of Jiangsu Power Grid, the advantages of telematics network are mainly: 1 increase information capacity and improve scalability; 2 improve information transmission speed and improve system real-time; 3 greatly improve the reliability of data transmission.
5 Conclusions From the trial run status of the three kinds of network communication methods of Jiangsu Power Grid EMS, the effect is relatively good. The next step will be fully promoted according to the plan, and all of the sites will implement TASE.2 communications; 500kV substations and some large-scale power plants all use IEC60870-5-104 network communications; the use of conventional RTUs and smaller power plants will increase. Terminal server mode to achieve network communications. Strive for full implementation of network communications in 2003, so that the network communications applications in Jiangsu Power Grid to a new level.
Therefore, the use of more advanced communication means to transform the original telecontrol communication method is very necessary. With the completion and deployment of the Jiangsu Power Data Network, Jiangsu Province has conducted research and application of EMS network communications.
1 Telecontrol Communication Networking 1.1 Selection of Network Technology Although telecontrol communication requires high real-time performance, with the advancement of network technology, it is now possible to obtain the required network speed at a reasonable cost. For networks within the EMS and within the substation, Fast Ethernet based on switching technology is undoubtedly the best choice. At the 10 Mbit/s level, Ethernet may also have competitors, such as token ring networks. However, after entering the rate of 100Mbit/s and higher, Ethernet is the first choice in the LAN field regardless of performance or price. Other high-speed network technologies, such as ATM and FDDI, although not widely used in local area networks, can be used as a wide area network solution for connecting a master station to a master station, a master station, and a substation.
1.2 Transport Layer Protocol and Routing Function Due to the great success of the Internet, TCP/IP has become the de facto standard from the LAN to the WAN. TCP/IP uses IP to complete routing and TCP to implement transport layer control. Both functions and efficiency can meet the needs of telecontrol communication. Due to its extensive use on the Internet, it has led to the development and production of a large number of TCP/IP-based hardware and software worldwide. It can be said that TCP/IP is currently the most widely supported, fastest-growing and most mature network protocol. Therefore, IEC also selected TCP/IP as the basic protocol of IEC60870-5-104 and TASE.2.
1.3 Choice of application layer protocol With TCP for transmission control, in principle, any application layer protocol can be selected. Taking into account the interoperability between different systems, in order to make the system has a better openness and scalability, should be selected in the international standard agreement. Currently selected and possibly selected protocols in the future include: IEC60870-5-101, IEC60870-5-104, IEC60870-6 (TASE.2), IEC61850. The basic characteristics of these application layer protocols are shown in Table 1.
2 application layer protocol in the EMS application According to the characteristics of different protocols and their current use in the EMS, you can get the following conclusions:
a. From the application requirements and the attitude of the IEC, it can be seen that the telecontrol communication network is the trend of the times, and it is a wise choice to gradually carry out network transformation.
b. The standardization, standardization, and object-oriented development of EMS are development trends, and new protocols with object-oriented features can be selected on the premise of conditions permitting. This is a step-by-step process from the top to the bottom and from the main station system to the substation system.
c. TASE. Both IEC 61850 and IEC 61850 originated from the research and promotion of UCA (Utility Communication Architecture) by China Electric Power Research Institute (EPRl). They are based on another protocol ISO 9506 (Manufacturing Message Specification) and use the services provided by MMS. From Table 1, it can be seen that IEC recommends that IEC 61850, IEC 60870-5 and IEC 60870-6 be selected for use in different situations. Although IEC 61850 is not finalized at present, it can be guaranteed that the investment in TASE.2 will not be wasted due to the promotion of IEC 61850. .
Based on the above analysis, we determine the following principles:
a. Establishes network communication between the master station and the master station and selects TASE.2;
b. Network communication between the main station and substation and use IEC60870-5-104;
c. For the local monitoring system is relatively simple or there is no local monitoring of the RTU device to achieve network communication by IEC60870-5-104;
d. For RTU devices that do not have network capabilities, use the terminal server to connect to the Internet or directly use the serial channel, and then use IEC60870-5-101. The terminal server mode is recommended.
3 Jiangsu power data network construction In order to solve the problems existing in traditional telecontrol communication, the application work of EMS network communication must first be complete data communication network. In 2000, the Jiangsu Provincial Electric Power Company established a three-level ATM-based data network, which is divided into a backbone exchange layer and an access layer. The backbone switching layer includes the headquarters of the Jiangsu Electric Power Company and all 13 regional power supply companies. The Northland Telecom Passport 15000 is used as the backbone ATM switching device. The switching capacity is 40 GB, the trunk bandwidth is 622 Mbit/s, and the Passport 7480 is selected as the backbone node service access device. The contact layer includes 500kV substations and major power plants in Jiangsu Power Grid, and selects Northern Telecom Passport 5430. It uses the 2Mbit/s ATM trunk to access nearby backbone nodes according to the principle of nearest access. During the implementation of IP services, Jiangsu Power Data Network built a VPN for real-time control services using the IP VPN function provided by the Northern Telecom Passport Switch (referred to as real-time VPN). The real-time scheduling system for each node directly accesses the real-time data through the network communication workstation. VPN, adopts IEC60870-6TASE.2 agreement to carry on the real-time data communication between the province, the ground adjustment EMS/SCADA system. The work of directly accessing the RTU information of the provincial power plants and 500kV substations via the Internet is currently under way.
4 The use of communication protocol in the Jiangsu Power Grid EMS The application of the Jiangsu Power Grid EMS data network communication is divided into the following three aspects: 1 to adjust the inter- provincial TASE.2 communication; 2 between the power plant or substation and provincial transfer IEC60870-5 -104 Network communications; 3 Power plants or substations communicate through conventional telecontrol protocols between terminal servers and provincial transmissions. The schematic diagram of the three communication methods is shown in Figure 1.
IEC60870-5-104 communication is used between power plants or substations and provincial transmissions. At present, Jiangsu Power Grid adopts the IEC60870-5-04 network communication protocol and has put into operation five power stations, namely Sheyang Port, Xiagang, Yancheng, Xutang, and Shubi, and Dongshan Bridge 500kV substation. The information transmission effect is very good. The on-site telemetry and remote signal change to the main station main wiring diagram reaction time, the telemetry is less than 4s, the remote signal is less than 3s, and when using the conventional telecontrol communication method, the response time is greater than 10s.
Power plants or substations communicate through conventional telecontrol protocols between terminal servers and provincial transmissions. As can be seen from Figure 1, this communication only uses network transmission, its application layer protocol or conventional telecontrol protocol, the true transmission rate is limited by the RTU serial port rate. However, due to the omission of modem equipment at both ends, its bit error rate is greatly reduced, and the reliability of the communication channel has been greatly improved. Currently, only one Shimonoseki power plant is put into operation by Jiangsu Power Grid in this way, and the effect is relatively good. The adoption of this communication method will greatly increase the reliability of information transmission and is more suitable for smaller power plants or substations.
Judging from the experience of Jiangsu Power Grid, the advantages of telematics network are mainly: 1 increase information capacity and improve scalability; 2 improve information transmission speed and improve system real-time; 3 greatly improve the reliability of data transmission.
5 Conclusions From the trial run status of the three kinds of network communication methods of Jiangsu Power Grid EMS, the effect is relatively good. The next step will be fully promoted according to the plan, and all of the sites will implement TASE.2 communications; 500kV substations and some large-scale power plants all use IEC60870-5-104 network communications; the use of conventional RTUs and smaller power plants will increase. Terminal server mode to achieve network communications. Strive for full implementation of network communications in 2003, so that the network communications applications in Jiangsu Power Grid to a new level.
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