Ashburton SMS Detailed Design and Commission Sequence

SMS Replacement 1

The scope was to produce a detailed design for the largest substation SMS solution to date.  Deliverables included detailed design drawings, installation specs, SCADA and a system project overview.  Transpower’s aging fleet of Remote Terminal Units (RTUs) no longer have the required capacity to perform the transfer of the increasing volume of data required from today’s substations.  The install base was commissioned in the early 90’s and the manufacturer no longer supports a number of the models currently in use.

To date Transpower has only replaced RTU with SMS’s at smaller sites.  The commission sequence with these smaller sites has been a “big bang” approach; with the whole site being commissioned onto the SMS in one or two days with the loss of some information and control during this small commissioning window.

The big bang approach was not feasible for Ashburton, the first large site to have an SMS with expected commissioned works to span more than one month, due to the large amount of work required.  Work included installation of Cooper SMP I/O units, SEL2440 bay controllers, fibre cables and Moxa Serial to Ethernet converters in protection panels, Junction Boxes and Transformer Control Cubicles along with new protection settings for SEL421 and SEL451 relays to enable fibre Ethernet ports.

A decision was made to use the “best-of” function which is a feature of the Cooper SMP16 device.  The best-of function allows two data points to be mapped to one SCADA point with a 3rd point acting as the quality bit to determine which is the live data point. The SMP16 is the substation controller and makes up part of the Transpower SMS solution.   

The first part of the project was to slave the existing RTU off the new SMS.  All these points then became the first part of each SCADA point in the best-of function.  The configuration was then mapped with the second part; that being the location of the point once it had been moved (SMP I/O unit or SEL2440).  A quality point was then added to the configuration to determine which point was the live one.  Generally the quality point was the online status of the new SMP I/O or SEL2440 device.

The best-of function enables one configuration for the whole commission sequence but also allows the work to proceed in any order and with no time constraints due to loss of data.  At the end of every day the site was returned back to regional control full operationally.