Reducing DC power system operating costs through supervisory control software changes

This paper discusses the operational merits and cost savings that can be achieved by introducing automatic functionality into the supervisory control system of older DC power systems. In the early 1980s BT deployed a new range of modular power systems (PS2000) to support its "System X" digital switching equipment. Based on an Intel 8085 microprocessor, the Power Management Scheme 2000 (PMS2000) provided overall system control, data logging, fault event monitoring and a battery discharge routine. By re-engineering the existing PL/M source code and designing new software modules, it has been possible to emulate some of the attractive features found in modem day power systems. Three of the newly introduced functions are covered in detail and their significance in changing the way in which BT manages its DC platform is explained. The paper outlines the PMS2000 control philosophy and explains how the new functions were designed and structured to fit into the original software program. It also highlights the problems encountered during the design and build phase of the development project and describes some of the techniques used to ensure the software was correctly debugged and tested. The paper closes with a financial analysis of the claimed benefits A cost comparison is used to highlight the advantages that can be achieved through a change of DC platform operating philosophy. Using BT\´s network estate as an example, the paper concludes that a payback of 2.5 years can be realised when the new operating scheme is applied to a population of 23,000 plant items.