50,000-point CitectSCADA system links 1000 remote sites

Citect has supplied a 50,000-point CitectSCADA system to Yorkshire Electrical Distribution Limited (YEDL) for remote control and monitoring of hundreds of remote sub-stations in the West and South Yorkshire area. The Citect control system employs remote RTUs communicating to two central servers using Citect's free-of charge DNP3 driver, which has been specially expanded by Citect to accommodate around 1000 remote sites.

Graeme Melia, Technical Engineer at YEDL, says: "CitectSCADA came highly recommended. We liked the fact that it is a very expandable system and extremely easy to use. Using the software, we have just five templates covering all aspects of the distribution control system; if we want to add a new site we just add a line and tell the SCADA system which template to use, then its 'job done'. The system was developed and installed by ABB, who worked with the support of the Citect professional services."

YEDL is the distribution network operator for a major part of West and South Yorkshire, an area encompassing cities such as Leeds, Bradford, Sheffield and Hull. The company has implemented the £40,000 distribution control system as part of OFGEM's Information Incentive Project, an initiative that is aimed at improving the quality of supply to users by achieving superior control and monitoring of the distribution network.

Major benefits

Graeme Melia states: "The Distribution Control System offers a number of major benefits, both to customers and to us. First, quality supply improvements are gained through reductions in the number of supply minutes lost. With the Citect system we can switch networks around to restore supply after faults have occurred; if we have a fault between two substations we can isolate the section between the two and restore power quickly. Second, the ability to set up protection remotely on pole-mounted auto reclosers to enable safe working on the system; this is imperative, as some of the work is undertaken on live conductors. Third, the fact that we have remote control of equipment scattered all around of our supply area means that we are able to address the costly issue of travel times to these sites.

"We decided to use our existing private mobile radio (PMR) as our transmission medium because the technology already exists at many of our sites. The advantages of PMR are that it is mature, well proven, and offers a blanket coverage that is totally independent of the electricity distribution network. Other systems were available but the coverage they provided and ongoing cost were issues that decided us against them."

The PMR system is used in conjunction with Citect's DNP3 (Distributed Network Protocol) driver, which comes as part of CitectSCADA. DNP3 is an open and public protocol that is used mainly in the utilities industries. It is designed to allow reliable communications in the adverse environments to which electric utility automation systems are subjected, being designed specifically to overcome distortion induced by EMI, ageing components whose expected lifetimes may stretch into decades, and poor transmission mediums.

Because DNP3 is based on the IEC 870-5 requirements, it is suitable for application in the entire SCADA environment. This includes RTU-to-IED communications, master-to-remote communications, and even peer-to-peer instances and network applications. Being an object-based application layer protocol, DNP3 has the flexibility to support multiple operating modes such as poll-response, polled report-by-exception, unsolicited responses and peer-to-peer. It permits multiple masters and encourages distributed intelligence.

The PMR/DNP3 network, presently encompassing 1000 sites, is linked to a central control room housing two 50,000 point servers, one of which is configured as a cold standby, and four display clients. The clients are manned 24/7 by the control engineers who manage the system. As part of the control process all events are recorded and archived to an external log, providing a transparent operating record for the distribution control system.