SCADA Systems For Real Time Data

A Supervisory Control and Data Acquisition system uses both computer hardware and software to gather and analyze real time data, manage supervisory operation, respond to error conditions with alarms, and provide operations personnel with an interface to the system.

The Customer’s System

The Chilled Water Systems Utility, a part of University of North Carolina at Chapel Hill’s (UNC-CH) Energy Services Department, initiated a project to replace the legacy Supervisory Control and Data Acquisition (SCADA) system with a best-in-class SCADA that could accommodate the large and complex existing system and provide for future growth.

Chilled Water Systems operates the campus District Cooling System, consisting of five plants totaling over 50,000 tons cooling capacity, a thermal storage system with 5,000,000 gallons of chilled water storage, and 26 miles of underground distribution pipes. This system provides chilled water to 154 main campus buildings, including laboratory, medical, office, and dormitory facilities. Eight smaller systems isolated from the main campus are also managed by the SCADA system.

A SCADA system uses both computer hardware and software to gather and analyze real time data, manage supervisory operation, respond to error conditions with alarms, and provide operations personnel with an interface to the system. The UNC SCADA system utilizes the campus network to tie all elements of the control system together, from controllers and I/O, to enterprise databases and applications. Physical and logical isolation is used as required to maintain security for the control system.

The Replacement Project

The SCADA Replacement Project consisted of several phases spanning three years:

• Phase I – Customer requirements development and education about current technologies along with vendor sales presentations

• Phase II – Specification development and related bid/purchasing documents

• Phase III – SCADA bidding, evaluation, vendor selection, and award

• Phase IV – Vendor implementation for two plants and building interface/metering system (152 buildings) with customer support team

• Phase V – Customer implementation for three plants, billing interface, and Vijeo™ Historian software with vendor support contract

• Phase VI – Decommissioning legacy system once new back-up system is in place

Experience with the existing system made it clear that any new system would need careful evaluation and testing to ensure successful operation over the UNC network. This was particularly true when communicating with the campus buildings to monitor and collect operational and billing data. To that end, Maverick Technologies, an engineering, systems integration, and operational consulting firm, was brought in to assist with development of the specifications that were needed to successfully deploy a SCADA system that would meet UNC requirements. Various vendors were invited to describe their products and optionally demonstrate their capabilities. This saved the university time and expenses during a period of financial restrictions on travel, while helping the UNC staff understand SCADA offerings from a variety of vendors and develop the bid specification.

The UNC purchasing department selected a ‘best value’ method for bidding the “Replacement SCADA Project.” Due to the sensitive nature of information that would be needed by bidding vendors, pre-qualification was an essential part of invitation for bids. Four well known and respected SCADA vendors participated in the bid phase of the project, including a team comprised of Schneider Electric and Graybar. All bidding vendors were required to provide copies of their software for evaluation by the

UNC team. The bid evaluation process included information requests from the vendor to resolve any concerns or questions that might arise.

As they proceeded with their evaluation, UNC personnel expressed concern about one of the estimates. They believed that too few hours were estimated for the chiller dispatch program and its operator display.

In response, the Schneider Electric/Graybar team developed a display and programming within Vijeo Citect™ and submitted it as a justification ofthe hours. UNC’s Timothy Ross, SCADA Replacement Project Manager, turned this application over to one of his developers who installed it and, with only minor modifications, UNC was able to control its district cooling system plant staging with the Vijeo Citect application. This demonstrated value and capability for the SCADA offering of Schneider Electric and

Graybar, and the Vijeo Citect SCADA product was selected as the replacement system.

Vendor Observation

Daryl Gilbert of Graybar stated, “Vijeo Citect will be a huge asset to UNC Chapel Hill’s Chilled Water Systems. Throughout the selection process the UNC staff continually focused on the features, benefits, reliability and the ease to implement redundancy. For those of us that have worked with other SCADA platforms, it’s no surprise that Schneider Electric was the clear choice.”

Now that UNC-Chapel Hill has the new system installed, everyone involved is proud to have completed the job within the schedule and budget goals, and met robust solution expectations with proven architecture, flexibility, and reliability.