畢業(yè)設(shè)計(jì)外文翻譯3

1、© Tianjin University and Springer-Verlag 2008Accepted date: 2007-12-20.*Supported by National Natural Science Foundation of China(No.50777040. CONG Wei, born in 1978, male, Dr, lecturer.Correspondence to CONG Wei, E-mail:weicong.Communication Service Model for Wide Area ProtectionSystem Based o

2、n IEC 61850*CONG Wei(叢 偉 , PAN Zhencun(潘貞存 , GAO Zhanjun(高湛軍 ,ZENG Yuxiao(曾煜曉 , ZHAI Yunjuan(翟運(yùn)娟 (School of Electrical Engineering, Shandong University, Jinan 250061, ChinaAbstract :In order to meet the requirements of information exchange varieties and manners in wide area protection system, a comm

3、unication service model based on IEC 61850 is proposed. This service model can realize communication consistency and cooperation between different types of devices. Furthermore, the communication reliability and time delay performance are guaranteed to meet the requirements of relay protection from

4、the upper layer. Message structure of generic sub-station event (GSE and its communication mechanism are discussed. General methods to com-municate digital information by generic substation status event (GSSE and communicate analog sampling information by sampling analog value (SAV of GSE are propos

5、ed. Keywords :wide area protection; IEC 61850; communication ; service modelWide area protection system has increasingly be-come a new study area. Though there are different un-derstandings about the function and configuration in wide area protection system, one aspect is certain that a high perform

6、ance communication system is necessary to obtain information of power system in wide area. There are different requirements to communication system performance according to different functions completed by wide area protection system1. For example, relay protection and some automatic control systems

7、 have a high requirement in the operation reliability and time delay, so to the communication system, while some other automatic control systems have lower requirements in time delay, their requirements to communication system are accordingly low. A communication system that can meet different requi

8、rements is needed to exchange all kinds of messages. The communication system men-tioned here includes not only communication devices and network, but also communication protocol, service and so on2. There is no universal data exchange model in the present power communication system. And most commun

9、ication protocol cannot meet some high re-quirements in communication time delay and reliability. The usage of usual point-to-point communication model and traditional LAN communication technology cannot guarantee time delay and reliability of synchronous in-formation transmission in wide area3,4.Co

10、mmunication service model for wide area protec-tion system based on IEC 61850 is therefore studied. Message structure of generic substation event (GSE, its communication mechanism and the service model are discussed. The focus is to propose general methods to communicate digital information by gener

11、ic substation status event (GSSE and communicate analog sampling information by sampling analog value(SAV.1 Information type and communication re-quirements in wide area protection sys-temWide area protection system should provide with the traditional functions of three defensive lines. More-over, i

12、t can cooperate with the functions of the three de-fensive lines, which operate independently in a normal way. The implementation of all the functions must be based on a powerful communication system. Different functions in wide area protection need different kinds of information and have different

13、requirements to commu-nication system. Wide area relay protection function has the highest requirements because of the characteristics of rapidness and reliability of relay protection system. So we mainly discuss communication service model forCONG Wei et al: Communication Service Model for Wide Are

14、a Protection System Based on IEC 61850 227 wide area relay protection system.According to the algorithm applied, information for wide area relay protection system can be classified into two kinds. The first is digital information of calculation results of relay protection devices, such as operation

15、in-formation of distance protection or the estimation re-sults of direction element. The second is analog sam-pling information, such as current and voltage sampling information. According to the classification of substation information and communication delay requirements of relay protection relate

16、d information in IEC 61850, any information must be delivered reliably within 4 ms59. In wide area protection system, information ex-change between any two protection devices(intelligent electronic device, IED, no matter they are the same type of devices from one manufacturer, or different types of

17、devices from different manufacturers, should meet re-quirements of data interoperability and transmission rapidness and reliability10. So an efficient and general data object model needs to be constructed and given standard semantic definition.2 GSE modelA data communication model called generic sub

18、sta-tion event (GSE is defined in IEC 61850. Based on the concept of automatic distribution, the model can rapidly and reliably transmit I/O data within the whole system. It fully supports TCP (UDP/IP protocol as well as com-munications in LAN and WAN. Multicast technology is used to transmit one GS

19、E message to several physical devices at the same time. Besides, IEC 61850 makes strict rules on communication performance of GSE mes-sage in order to make sure that the time delay of indus-trial information between IEDs will be less than 4 ms.There are two kinds of message structures according to d

20、ifferent application characteristics. One is GOOSE, which supports exchange of public data organized by DATA-SET. The other one is GSSE, which is used to transmit information of status variable (digital informa-tion. GSE is used to exchange data attribute ensemble value. IEC 61850 has standard defin

21、ition on semantics and syntax, as well as definition on message of GOOSE/GSSE. According to this standard definition, IED constructs data objects and transmits them with standard GOOSE/GSSE messages to guarantee coopera-tion of application data between different IEDs and communication quality from t

22、he upper layer11.IEC 61850 is not a communication protocol and it does not define details about communication protocol. Instead, it is a system standard, which is independent of any specific communication network and protocol. IEC 61850 defines models of communication data and ser-vice. It is just a

23、 framework without any content. So users can define and expand specific contents that they need. Protection based on different principles may define and expand data attribute according to different func-tions. The definition and expansion should be carried out according to IEC 61850 standard so that

24、 the data between different protection devices have a mutual un-derstanding 12.3 Publisher/subscriber mechanismGSE message is exchanged with publisher/sub-scriber service mechanism1315. Within this service, data receiver acts as a client while data provider as a server. One physical device could eit

25、her be a server or a client. Publisher/subscriber service mechanism supports one device spontaneously and sends messages to other devices, which is significant to the functions of relayprotection and fast control. In publisher/subscriber ser-vice mechanism, once there are some data, they will be tra

26、nsmitted spontaneously through a predetermined path without any intervention to guarantee the rapidness of communication. Take GOOSE communication as ex-ample, its publisher/subscriber model is shown in Fig. 1. If one or more data attributes of data objects in pub-lishers DATA-SET change, the “publi

27、sher” service of the publisher will refresh the buffer and write the changed values to the sending buffer. GOOSE messagewill send these values by multicast technology. The sub-scriber reads these values from the receiving buffer and informs the application the appearance of the new data. The publish

28、ers GOOSE-Control-Block is used to con-trol the whole process.Publisher/subscriber service mechanism is suitable for wide area protection system with distributed system. When fault occurs, information of some certain IEDs will be delivered to some other IEDs simultaneously and information from other

29、s will be received. Now IED acts as not only the server (data publisher but also the client (data subscriber. The server publishes the data; any client who wants to get the data can describe theTransactions of Tianjin University Vol.14 No.3 2008 228GOOSE/GSSE message.Fig.1 GOOSE communication servic

30、e model based onpublisher/subscriber4 GOOSE and GSSE modelsGSSE is only used to transfer two-bit digital status information, including protection judgment informa-tion, switch operation information, and so on. The struc-ture of GSSE message is shown in Tab.1.Tab.1 GSSE message structureParameter Par

31、ameter type Description Sending IED Visible-String ID of sending IED TBTIME6Time tab of GSSE messageSqNum INT32UGSSE message sequence number StNum INT32U Event sequence number HoldTimINT32UHolding time of GSSE messageBackTim INT32UDuration time from eventoccurrence till now PhsID INT16U Fault phase

32、Value CODE ENUM(00 invalidity or transient(01 false of close(10 true of open (11 invalidityGOOSE and GSSE both adopt publisher/subscriber mechanism for the exchange of information. Their communication service models are similar. The differ-ence is that GOOSE sends the member value of DATA-SET, while

33、 GSSE sends two-bit status information. GOOSE communication model uses GOOSE-Control-Block to control the whole process, while in GSSE, GSSE-Control-Block is used. The description and defi-nition in GOOSE-Control-Block can also be used in GSSE-Control-Block.The communication service model defined in

34、 IEC 61850 is abstract. It is independent of the specific com-munication network and protocols. To use GSE model in Ethernet or other network, it has to be mapped to spe-cific communication protocol stack through specific communication service mapping (SCSM . The reli-ability and specific time delay

35、 of information transmis-sion depends on SCSM and specific communication pro-tocol stack16.5 Sampling analog valueIn wide area protection system, sometimes it is nec-essary to exchange SAV from measuring points. In GSE,GSSE exchanges two-bit status information, while GOOSE supports exchange of publi

36、c data organized by DATA-SET, which can be used to transmit analog sam-pling information. However, in wide area relay protec-tion system, there are some special requirements in transmission delay and reliability, which should be dis-tinguished from usual analog measurements transition in substation

37、automation system. IEC 61850 has special definition on SAV, providing methods to report SAV systematically and time control measures so that the transmission time delay is short while sampling count-ing and sequence are constant. It is suitable for exchang-ing analog sampling information reliably in

38、 a very short time delay17.Since SAV belongs to one sort of GOOSE, it could be applied to value exchange of DATA-SET. There de-fine a variety of public data in IEC 61850, which mainly includes six categories: status information, measurement information, controllable status information, controlla-ble

39、 analog setting value information, status setting value information, and analog setting value information.SAV uses sampling values in public data of mea-surement information. The exchange of sampling values is based on publisher/subscriber mechanism. The pub-lishers sampling value control(SVC block

40、controls the whole process, which is the same as GOOSE, and their communication service model is also the same. Com-pared to other public data, exchanging SAV has its own characteristics.(1 There are two methods to exchange SAV be-tween the server and clients: one adopts multicast-application-associ

41、ation (MAA, and the other adopts two-party-application-association(TPAA.CONG Wei et al: Communication Service Model for Wide Area Protection System Based on IEC 61850 229 TPAA provides two-direction association oriented information exchange, the application association of which is reliable and infor

42、mation flow is controlled end-to-end. The term “reliable” mentioned here means that application association relies on provided measures out-side. End-to-end information flow control means that information source will not send too much information to overflow the storage of the destination. The assoc

43、ia-tion, data exchange and release of TPAA are shown inFig.2.Fig.2 Principle of TPAAMulticast-application-association (MCAA provides single direction information exchange. There is a multi-data-exchange between one source (server and several destinations (clients. Single direction information ex-cha

44、nge provides enough information for receiver to in-terpret contexts definitely. Clients can detect loss and repetition of the information, and the receiver can sug-gest to the clients on the information loss and tell them to give away repeated information. The principle ofMCAA is shown in Fig.3.Fig.

45、3 Principle of MCAAExchange of IED information in wide area protec-tion system is no longer point-to-point. At present it is one-point-to-several-points. MCAA model should be adopted since rapid data exchange is carried out in defi-nite direction.(2 It is necessary to specify the sampling frequency,

46、 at which the input signals has to be sampled. In IEC 61850, both MsvCB and UsvCB have defined parameter “SmpRate”, whose attribute value defines system sam-pling frequency.(3 Wide area protection systems may require syn-chronous sampling. Optional parameter(OptFlds isdefined in SVC, and its attribu

47、te provision is included in optional field of sampling value message sent by MsvCB, one parameter of which, SmpSynch, is used to illustrate whether sampling is synchronous according to system clock.(4 GSSE message sends two-bit status information which can express four different statuses (00 11 in b

48、i-nary system at most, while SAV message sends sampled analog information. Sampling value data belongs to pub-lic data, which is defined in Section 7-3 of IEC 618502.6 ConclusionsIn this paper we have proposed and discussed the communication service model based on IEC 61850 to meet the requirements

49、of information exchange varieties and manners in wide area protection system. Communi-cation service model and network are necessary parts of a communication system. Communication service model mainly solves problems of communication consistency and cooperation between different types of devices and

50、 it can guarantee reliability and time delay performance to meet the requirements of relay protection from the up-per layer. Communication network ensures high com-munication performance with physical equipment. We have also discussed message structure and communica-tion mechanism of GSE and propose

51、d general methods to communicate digital information by GSSE and com-municate analog sampling information by SVA. References1 Xu Lizi. Requirement of IEC 61850 to performance ofmessages for substation automation system J .P ower System Technology, 2003, 27(5: 1-3,19(in Chinese.2 IEC 61850. Communica

52、tion Networks and Systems inSubstations S . 2003.3 Gao Zhanjun, Pan Zhencun, Bian Peng et al. A datacommunication model for microprocessor based protec-tion based on IEC 61850 standard J . Automation of Electric Power Systems, 2003, 27(18: 43-46(in Chinese.4 Peng Hui, Jin Wuqiao, Cheng Haiyan et al.

53、 Implemen-tation and on-site application of TASE.2 protocol in wide area network J . Power System Technology, 2003, 27(5: 43-46(in Chinese.5 Apostolov A, Tholomier D. Impact of IEC 61850 onpower system protection C . In: Power Systems Con-ference and Exposition. Hong Kong, China, 2006. 1053-1058.6 S

54、u Sheng, Li K K, Zeng Xiangjun. Distribute coordi-Transactions of Tianjin University Vol.14 No.3 2008 230 nated wide area current differential protection based on IEC 61850 C . In: IEEE Region 10 Conference. Hong Kong, China, 2006. 1-4.7 Apostolov A. Object models of protection devices inIEC 61850 C

55、 . In: PES TD 2005/2006. Texas, USA, 2006, 915-920.8 Shephard B, Janssen M C, Schubert M. Standardizedcommunications in substations C . In: IEE Seventh International Conference on Developments in Power System Protection. Amsterdam, the Netherland, 2001. 270-274.9 Sidhu T S, Yin Yujie. Modeling and simulation forperformance evaluation of IEC 61850-based substation communication syste