IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 39, NO. 3, MAY/JUNE 2003 619 Advanced Modeling Techniques for Dynamic Feeder Rating Systems George J. Anders, Fellow, IEEE, Andrzej Napieralski, Senior Member, IEEE, Mariusz Zubert, and Mariusz Orlikowski Abstract—This paper describes the technical details of an ad- vanced model for use in real-time cable rating systems. Real-time cable rating systems perform calculations of steady-state and emergency cable ratings in real time; several such systems have been installed to maximize asset utilization without compromising cable system reliability. An example of a complex tunnel instal- lation, featuring four self-contained fluid-filled and cross-linked polyethylene cable circuits, is described in detail, highlighting key issues of relevance to real-time systems. Index Terms—Buried cables, cables in ducts, cables in tunnels, power cables, real-time ratings, state estimation. I. INTRODUCTION M ANY transmission lines in electric utilities using electric power cables were designed with thermal limits based on conservative assumptions. This was the result of a lack of real knowledge about cable thermal environments. Because of the difficulties in siting new lines in cities, there is great pressure for increased power transfer on some older lines. Dynamic feeder rating systems are an important alternative to analytical approaches for determining the real-time con- ductor operating temperature and corresponding real-time cable ratings. One such system, MAXAMP, has been developed by Kinectrics Inc, Toronto, ON, Canada. The advanced modeling features required in such systems are described in this paper. II. USER INTERFACE AND DATA ACQUISITION SYSTEM A. What is a Dynamic Feeder Rating (DFR) System? A DFR system performs real-time calculations of steady-state and emergency cable ratings. For a given cable installation maximum operating temperatures and duration of an emer- gency (e.g., 20 min, 4 h, etc.), the software computes the maximum current that the cable can carry for the specified conditions. It can also calculate the maximum duration of a given overload condition before the conductor emergency temperature is reached and the maximum temperature reached during the specified period of time and emergency loading. Paper MSDAD-A 02–48, presented at the 2002 Industry Applications Society Annual Meeting, Pittsburgh, PA, October 13–18, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Industrial Au- tomation and Control Committee of the IEEE Industry Applications Society. Manuscript submitted for review October 15, 2002 and released for publication January 22, 2003. G. J. Anders is with Kinectrics Inc. Toronto, ON M8Z 6C4, Canada (e-mail: george.anders@kinectrics.com). A. Napieralski, M. Zubert, and M. Orlikowski are with the Technical Univer- sity of Lodz, 93-590 Lodz, Poland. Digital Object Identifier 10.1109/TIA.2003.810648 Fig. 1. Example of a simultaneous implementation of MAXAMP for multiple cable installation. CS: cross section; C: circuit; CB: cable. The DFR system is accessed either through a dialup connec- tion from another Personal computer (PC) using remote com- munications software, via modem or local area network. Once a secure connection is established, a user can monitor the DFR application running on the system. B. Data Acquisition System A DFR system is configured to link several distributed remote terminal units (RTUs), positioned at strategic locations along the cable route, to a main computing unit (CU) which is generally installed at a substation. Operation of the system is under control of the CU, typically an industrial-grade PC. The distributed RTU units are commer- cial data acquisition units requiring a power supply and a link for communication to the CU. The technology has proven highly re- liable for over ten years outdoors in Northern Ontario, Canada, monitoring transmission equipment mechanical performance. III. A DFR SYSTEM COMPUTATIONAL ENGINE A. Organization of Rating Calculations The DFR program can perform calculations in real time of steady-state and emergency ratings. Computational algo- rithms for the steady-state analysis are based on the standard Neher/McGrath [1] and IEC 287 procedures, [2], [3]. Time-de- pendent ratings are based on the method described in the IEC 0093-9994/03$17.00 © 2003 IEEE