CERN operates a large distribution network for the supply of electricity to the particle accelerators, experiments and the associated infrastructure. The distribution network operates on voltage levels from 400 V to 400 kV with a total yearly consumption of near to 1000 GWh. In the past, the laboratory has developed an in-house control system for this network, using the technologies applied to the accelerator control system. However, CERN is now working on a project to purchase, configure and install an industrial Electrical Network Supervisor (ENS). This is a state-of-the-art industrial control system completely developed and supported by an external contractor. The system - based on a scalable and distributed architecture - will allow the installation to be performed gradually, and will be tested while the existing system is fully operational. Ultimately, the complete electrical distribution network will be supervised with this new system, the maintenance and further development of which will be the complete responsibility of the contractor

Poulsen, S

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EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCHORGANISATION EUROPÉENE POUR LA RECHERCHE NUCLÉAIRECERN - ST DivisionPresented at the 3rd ST WorkshopChamonix, France, January 25 - 28, 2000CERN-ST-2000-017February, 2000AN INDUSTRIAL CONTROL SYSTEM FOR THE SUPERVISION OF THE CERNELECTRICAL DISTRIBUTION NETWORKS. PoulsenAbstractCERN operates a large distribution network for the supply of electricity to the particleaccelerators, experiments and the associated infrastructure. The distribution network operateson voltage levels from 400 V to 400 kV with a total yearly consumption of near to 1000 GWh.In the past, the laboratory has developed an in-house control system for this network, usingthe technologies applied to the accelerator control system. However, CERN is now workingon a project to purchase, configure and install an industrial Electrical Network Supervisor(ENS). This is a state-of-the-art industrial control system completely developed and supportedby an external contractor. The system — based on a scalable and distributed architecture —will allow the installation to be performed gradually, and will be tested while the existingsystem is fully operational. Ultimately, the complete electrical distribution network will besupervised with this new system, the maintenance and further development of which will bethe complete responsibility of the contractor.21 INTRODUCTIONCERN is supplied with electrical energy from Electricité de France (EDF) and Energie Ouest Suisse(EOS). CERN distributes this energy to all electricity clients on the sites via the distribution network,which consists of about 100 substations and an installed capacity of 400 MVA. Most electricalequipment is supplied by industry and is typical industrial equipment, not specific to CERN. Theelectrical equipment includes more than 300 devices with communication capabilities. Also, CERNinstalled 180 local electricity control systems (the CERN MICENE) during LEP construction, whenelectrical equipment was not equipped with remote supervision facilities. In total, the equipmentrepresents more than 100 000 analog and digital data entities (or data points).2 BACKGROUND2.1 The existing systemCERN has in the past implemented an in-house supervisory system, based on technologies andfacilities developed during the construction of the LEP accelerator. This existing system is organizedas a collection of computers, services and applications, which are not developed, operated ormaintained as an integrated and homogenous system. In the future, it is not viable to maintain orfurther develop this system, mainly because of the limited resources available at CERN.Furthermore, the data acquisition of the existing system is based on a request–reply paradigm,which used to be common to a number of CERN systems in different domains. This model hasbecome obsolete in the context of new developments such as the publish–subscribe paradigm, whichare more appropriate for this type of control system.2.2 Objectives and constraintsThe ENS will provide a coherent control system, which will cover all the needs of the operation of theelectrical network, while also providing the flexibility to suit future requirements via resource-effective evolutionary maintenance. By basing the ENS on an industrial control system, CERN canconcentrate its human resources on the overall system engineering while reusing implemented andproven industrial solutions.The ENS will ultimately cover all layers of the supervision infrastructure using industrialcontrol technologies, from the lowest level of field communication with the electrical equipment, tothe highest level of user interfaces in the control rooms.Owing to the size of the electrical network, the ENS installation will be performed gradually,and has to be done in parallel with the operation of the existing system. The project has two phases: Inthe first phase the ENS will reuse and integrate the existing CERN Front End (CFE) computers usedfor data acquisition, and in the second phase it will replace the CFEs with industrial front ends, thusproviding a complete industrial control system.2.3 Selection criteriaThe ENS will be based on an industrial control system, satisfying a number of criteria to fulfil thespecific requirements for a system to be implemented in an experimental physics environment.Specifically, there are important requirements for a scalable and distributed architecture with a highdegree of openness for integration.2.3.1 ScalabilityThe scalability of the system is essential to the constantly evolving CERN context. CERN plans toexpand the distribution network in the future for the construction of the LHC, and the electricalequipment is evolving, therefore demanding more supervision capabilities. The ENS is expandable, sothat it can manage bigger data quantities resulting from the evolution of the electrical network.2.3.2 DistributionThe equipment communicates via distributed local-area field-bus networks — each covering a limitedgeographical area such as an electrical substation —3and an important feature of the ENS will be a distributed data-acquisition module to interface thesenetworks. This module will be integrated into the existing site-wide CERN communication networks.The operator posts of the ENS must also be distributed and available from dispersed locations, such asmajor substations and offices.2.3.3 OpennessThe openness of the ENS is vital for integration into the CERN systems. The electrical equipment tobe supervised does not provide a homogenous communication interface. Only the lowestcommunication layers are governed by international standards, and the ENS must adapt to thespecificity of every type of equipment. Thus, the ENS process interface must provide programmingand configuration tools to support existing and future communication interfaces and protocols of theelectrical equipment.Similarly, openness is required at the general supervision level. CERN’s policy is to integratespecialized and domain-specific SCADA systems, such as the ENS, into a general supervisioninfrastructure for technical services. For this supervision, the Technical Data Server (TDS) has beeninstalled. The TDS is a middleware data server which is provided with data from specialized SCADAsystems and makes this data available to external applications and systems such as the CERN AlarmSystem (CAS), MMI clients, data logging systems, etc.Open communication facilities are important selection criteria for ENS. These will enable it tointerface with the TDS system and possibly other external clients needing data from the electricalprocess.3 ARCHITECTUREThe ENS will be based on a standard industrial system, which implements all modules of a controlsystem from data acquisition to user interfaces. In addition to the standard modules of the controlsystem, some particular ones will be developed for the integration of the ENS into the CERNenvironment.The following will be the main modules of the ENS.- Network Control Centre (NCC). The NCC is the standard central control-room facility, whichprovides all operational and management facilities of the system. The NCC consists of applicationand database servers, which are made available for access via X terminals throughout the site.The NCC is implemented on UNIX servers, and high availability of critical system componentswill be assured via back-up servers controlled by watchdog computers.- Front End (FE). The FE is the distributed data-acquisition interface, which will interface to theelectrical devices in the field. The FE will assume communication functions with these devicesand perform some distributed data processing such as time stamping of incoming data. The FE isimplemented on Windows NT PCs using special hardware, taking into account the environmentalhazards present in electrical substations. Based on a standard platform, the FE is adapted to thespecific electrical equipment at CERN.- Gateway to electrical data acquisition (GATED). The GATED module is the software modulespecifically implemented for the first phase of the project. It will integrate the existing CFE-baseddata-acquisition module and the devices connected to this module, such as the MICENEcomputers. The GATED will be installed in each existing CFE computer without changing thefunctionality of the existing processes.- Gateway to external systems (GATEX). The GATEX is the central module, which provides aninterface between the NCC and external clients such as the TDS. In the case of the TDS, theGATEX makes data available via a TDS-specific TCP/IP protocol.- Remote Terminal Unit (RTU). The RTU is the interface to equipment which does not havecommunication capabilities. The RTU also provides local supervision facilities independently ofthe NCC.4The overall system architecture and data flow of the ENS is illustrated in Fig. 1. The modulesdeveloped under the ENS project are depicted on a grey background.Bay level:Substation level:Control room level:General supervision level:Serial protocol IP protocolExistingsystemDirect wiringGATEXNCCGATED(s)CFE(s)MICENE(s)Electrical equipmentRTU(s)CASTDSExternalclientsFE(s)Figure1: System architecture and data flow of the ENS.4 COMMUNICATION4.1 InfrastructureThe ENS will be integrated into the CERN data communication infrastructure, which is based onindustrial standards and available for the interconnection of industrial control systems [1]. Allmodules of the ENS adhere to these standards (e.g. IP) and have been tested for cohabitation withother systems relying on the communication network.To ensure the communication with a few very important electrical substations, specialcommunication lines will be installed to guarantee a very high availability. These point-to-point linkswill use the existing optical-fibre infrastructure available at CERN.The NCC will comprise a number of servers and auxiliary systems, which have specialcommunication requirements regarding availability and bandwidth. The communication betweenthese machines will be implemented via an isolated segment, which only communicates with'authorized' systems on other networks, such as the FE and GATED modules. A simplified view ofthe ENS communication infrastructure is illustrated in Fig. 2.5Communicationsnetwork backboneFibre-optic linkOffice operator postTo external systems (TDS)Substation Front EndNetwork Control Centre computersFigure 2: Communication infrastructure.4.2 IntegrationThe ENS will be integrated in the CERN infrastructure at the substation level and at the general-supervision level. At the substation level this is done via the FE and GATED module, in some casesusing the RTU as process interface. At the general-supervision level it is done via the GATEXmodule.At the substation level, the FE will interface to electrical devices via multiple protocols andcommunication interfaces. These include INSUM, JBUS, MODBUS, SPABUS and proprietaryprotocols over RS-485 multi-drop serial buses, implemented for device-specific applications uniqueto each equipment type.The GATED will provide a single IP-based communication interface to all equipment, which isalready interfaced via the CFE. This communication interface will be based on the communicationstandard IEC 60870-5-101, which is an international standard for data transmission related toelectrical process control.At the general supervision level the Collaborative Component Bus (CCBus) [2] will provide anoff-the-shelf communication interface facilitating integration with any external supervision system.The data exchange of the CCBus is based on a publish–subscribe paradigm and implemented via aCORBA-compliant event bus.5 ORGANIZATIONThe complete ENS system will be delivered under a supply contract with an external manufacturer.This manufacturer has developed and installed similar systems for other clients operating electricaldistribution networks.The full development and configuration of the system is the responsibility of the manufacturer,who will also perform commissioning and all tests on and off the CERN site.CERN plays an important role in the engineering of the general system and in particular in thedatabase design used for the system configuration. The equipment specialists, who will ultimately usethe ENS for operation of the electrical network, have an important role in the definition of data pointsand human interfaces.6 CONCLUSIONThe ENS will be installed in two phases. The first phase, which includes the main developments suchas the GATED module, will be installed by the end of the 1999–2000 shutdown. The second phase,which will provide a complete industrial control system including the FE and RTU module, will beimplemented during 2000.Future plans for extensions include implementation of Distribution Management System(DMS) functions, such as contingency analysis and power-flow calculations.6REFERENCES[1] R. Lauckner, P. Liénard, R. Rausch, Data communication infrastructure available at CERNfor interconnection of industrial control systems, 1997.[2] P.S. Viegas, CCBus interface to external clients, EFACEC Sistemas de Electronica,Ref. 4ET997001.

An Industrial Control System for the Supervision of the CERN Electrical Distribution Network

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