IEC 61850 Application in Railway Traction Substation Monitoring and Control System
Preface
By the end of 2005, the total mileage of electrified railway in our country has more than 20000 km, traction substation of primary and secondary equipment variety, different interface standard, technical equipment level differences between different regions, so the traditional traction substation telecontrol system cannot meet the needs of multiple substation remote monitoring. How to utilize the high coverage of the Internet, through the seamless connection of information technology, build an efficient, inexpensive traction substation remote monitoring system has become a hot topic of concern.
IEC 61850 is IEC TC 57 in UCA 2.0 American experience and the IEC 60870 series standards of the European experience about the future of substation automation system is proposed on the basis of the communication system standard. The goal is to maximize the application of existing standards and widely accepted, the communication principle of intelligent electronic devices (ieds) in different manufacturers to achieve good interoperability between, and can adapt to the rapid development of communication and application technology. IEC 61850 is different from the traditional SCADA protocols, it is not a simple protocol, performance requirements, more involved in communication network object modeling, system and project management aspects of the specification requirements.
IEC 61850 adopts object oriented modeling method and abstraction, hierarchical mapping technology, through the specification system and project management, as well as conformance testing way to ensure the realization of the goal. And IEC 61850 is not only applicable to internal substation automation network communication, can also be applied to distribution automation, electric energy metering system, power plant automation system, wind power and other industrial automation field.
Based on the analysis of the status quo of traction substation equipment in China, on the basis of established based on IEC 61850 standard of traction substation communication system model of sub station and control center, dynamic information meet with IEC 61850 standard XML specification describes the monitoring center using IE browser, Java Script, and the Active X controls, implement multiple traction substation remote monitoring, on the premise of not to refresh the IE browser page to realize the dynamic display of the operation parameters and status.
1 The content and features of IEC 61850 standard
1.1 The contents of the IEC 61850 standard
In the early 1990 s, Europe and the United States has carried out the research at the same time, and formulate the corresponding standards. In order to avoid conflict, two standard IEC decision on the basis of UCA 2.0 data model and service, incorporate the results of UCA IEC standards, establish a worldwide uniform standard, IEC 61850, and formally approved in 2002. In terms of concepts, the IEC 61850 standard draft mainly around the following four aspects:
(1) function modeling. From the substation automation communication system communication performance (PICOM) requirements, defines the function model of substation automation system.
(2) data modeling. Using object-oriented method, defines the data model based on client/server structure.
(3) the communication protocol. Defines the data access mechanism (service) and to the mapping of the communication protocol stack, such as the transformer substation layer and intervals between the network USES the abstract communication service interface is mapped to the MMS (IEC 61850-8-1). In the interval between the layer and process layer network mapping into serial unidirectional multipoint or point-to-point transmission network (IEC61850-9-1) or the process of mapping based on the IEEE 802.3 standard bus (IEC 61850-9-2).
(4) the substation automation system engineering and conformance testing.
Definition based on XML (Extensible Make up Language) structured Language, describe the topology and substation automation system and IED structured data. In order to validate interoperability, Part 10 describes the IEC 61850 standard conformance testing.
1.2 the characteristics of IEC 61850 standard
The main characteristic of IEC 61850 standard has the following several aspects: (1) the hierarchical information. IEC 61850 substation communication network and system agreement draft standard puts forward the concept of stratification within the substation information, no matter from the concept of logic or from the physical concept, substation communication system are divided into three levels, namely the substation layer, spacing layer and process layer, and defines the communication interface between layer and layer.
(2) object-oriented unified modeling data object. IEC61850 standard USES the object-oriented modeling technology, defines the data model based on client/server structure. Each IED contains one or more servers, each server itself contains one or more logical device. Logic device contains logical node, logical node contains data objects. A data object is composed of data attribute public data named instance of a class. In communications, IED also play the role of the customer. Any customer can use the abstract communication service interface (ACSI) through the server to access the data object.
(3) the data from the description. With IEC 60870-5 series standard adopts some oriented data description methods, IEC 61850 standard for information adopts object-oriented self-describing. The self-describing self description of the data itself in data source, data is transmitted to the receiver with the self, don't need to for engineering data quantity, scale conversion, etc. Because the data itself with instructions, so transmission can be defined in advance without limit, simplifies the data management and maintenance work. For this purpose, the IEC 61850 standard provides a set of object-oriented data from description method: IEC61850 object name standard defines the equipment name, logical node name, instance number and the name of the class data to establish object name naming rules; IEC 61850 communication service standards using object-oriented method, defines the communication between the service object, for example, to get and set object values communication service, obtains the object list of communication services, data object value obtained a list of services.
(4) the abstract communication service interface (ACSI). IEC 61850 standard summarizes the necessary Communication services, information transmission in substation was designed independently of the network and the application layer protocol used by the Abstract Communication service interface (the Abstract Communication ServiceInterface, ACSI). In IEC 61850-7-2, the established standards compliant server must be provided by the communication service model, including the server model, logical device model, data model, data model and logic node set model. Customers by ACSI, by special Communication Service mapping (Specific Communication Service Map, SCSM) mapped to Specific protocol stack, such as Manufacturing Message Specification (Manufacturing Message Specification, MMS).
2 Traction substation sub model of communication
Our country existing traction substation automation equipment used by a wide variety, interface standards also each are not identical, some use RS232 / RS485 interface, some with TCP/IP interface, there are a few equipment has been using IEC 61850 standard interface. In order to adapt to a variety of configuration system, Beijing jiaotong university institute of electric power system and system control technology co., LTD Beijing DeWitt force joint design for traction substation child general communication model, and applied to the actual remote monitoring system of traction substation, sub station communication model is shown in figure 1.
Sub station communication machine has two functions: through RS232 / RS485 or TCP/IP interface to the underlying substation equipment real-time parameters and status information collected and stored in the local database; Establish a two-way Socket communication with the monitoring center via the Internet, according to the request from the monitoring center, the real-time data and state of the local database, and compatible with IEC 61850 standard equipment real-time information together, according to the IEC 61850 standard repackaged into XML file upload, also will command from the monitoring center according to their respective specifications (RS232/485 or IEC 61850) is forwarded to the underlying device is carried out. Communication machine generated upload Devices. The XML file.
A typical traction substation to upload the XML file size is about 2.82 kB. Sub station communication machine Socket communication between master station and once established, sub station is in a state of circulation to send.
3 Remote monitoring system of traction substation
Monitoring master station, located in the center of the electric power dispatch of each traction substation is through the Internet and communication machine set up the Socket communication, the system structure is shown in figure 2.
The front end of the monitoring system of monitoring and control system using IE browser, through the Java Script in the HTTP call Microsoft XMLDOMActiveX control, establishing the Socket communication with sub station communication machine, upload the XML file, according to monitor the user's requirements in real time. Specific implementation is as follows:
Among them, the "221.137.24.108:8080" said a certain traction substation communication machine IP address and Port number. So, in a similar way in monitoring master station from all monitored a communication machine reading real-time data and status, statistical analysis, according to the requirement of the user in the form of statement or graphics (such as using Java Applet technology) for display. Other users have access to monitoring master station all can see through their Internet explorer and standing on the same picture. With a Socket send way of communication and circulation, the client IE without page refresh, you can display system of real-time data and status.
4 Conclusion
This paper puts forward a kind of based on IEC 61850 electrified railway traction substation remote monitoring system, traction substation station and the communication between the monitoring center is used to meet the IEC 61850 standard XML and Socket communication way. Sub station is responsible for the collection of traction substation in real-time data stored in the local database, and upon the request of the monitoring master station, the dynamically generated XML file sent cycle. Main use IE browser, Java Script and Active X technology and multiple child stand to establish a Socket communication, on the premise of not to refresh the IE browser page to achieve real-time data and status of the system dynamic refresh. In this paper, the remote monitoring system through the Internet station connected to the monitoring center, without special telecontrol channel, greatly reduces the system cost, the XML technology based on IEC 61850 standard is linked together, to realize the seamless connection between each subsystem.