ELECTRIC POWER DISTRIBUTION ASSET …

1 ELECTRIC POWER DISTRIBUTION ASSET management . Osman Bulent Tor Mohammad Shahidehpour e-mail: e-mail: Information Technology and Electronics Research ELECTRIC POWER and POWER Electronics Center, Illinois Institute (TUBITAK BILTEN), METU, Ankara, Turkey Institute of Technology, Chicago, Illinois, 60616, USA. ABSTRACT conditions in real-time, and restoration of the faults that In this study, ASSET management strategies in POWER result in supply interruption for some customers due to the DISTRIBUTION systems are investigated chronologically based radial topology of the DISTRIBUTION systems (such as short on short-term, mid-term and long-term time scales.)

2 New circuit on the DISTRIBUTION feeder) are among the critical strategies and their interrelation and coincidence in different tasks of DUEs in the context of providing reliable POWER time scales are discussed. The central role of Information Technologies (IT) in ASSET management is emphasized with supply. POWER system assets are monitored through the supportive examples. Supervisory Control and Data Acquisition (SCADA). systems which help system operators monitor and control I. INTRODUCTION the system in real-time. SCADA collects real-time data The restructuring and liberalization developments from Remote Terminal Units (RTUs) installed in worldwide have increased the incentives for a cost substations and POWER plants, and distributed throughout effective and efficient use of available assets in the POWER system.

3 It scans RTUs at a frequency of about generation, transmission and DISTRIBUTION segments of the two to five seconds. These data are transmitted to the electricity industry [1]. Essentially, ASSET management , system control center and stored in the DISTRIBUTION which is the process of guiding the acquisition, use and management System (DMS) real-time database. The DUE. disposal of assets to make the most of their future tracks and manages loads, maintains voltage profiles and economic benefit and manage the related risks and costs maximizes the efficiency of the DISTRIBUTION system by the over their entire life cycle, has gained more importance in DMS.

4 Naturally monopoly transmission and DISTRIBUTION sectors Sub-transmission and DISTRIBUTION networks have a than before, like in the competitive generation industry. geographical reference. Geographic Information System This study categorizes the ASSET management (GIS), which stores spatial information about a utility's strategies in POWER DISTRIBUTION sector, based on short- assets for representing the location and condition of assets term, mid-term and long-term time scales. Short-term including switches, relays, transformers, poles, cables, ASSET management is related with the operational issues of provides a variety of functions for ASSET management in the network (Section 2), mid-term ASSET management is all time scales.

5 There are a large number of DISTRIBUTION associated with the maintenance of system assets (Section cables in POWER DISTRIBUTION systems, most of which are 3), and long-term ASSET management is concerned with the under the ground and constitute a complicated cable strategical planning of DISTRIBUTION systems (Section 4). network. Utilizing GIS, users can easily collect the information on the geographical DISTRIBUTION of cables II. SHORT-TERM ASSET management based on GIS maps. This will provide useful reference for (OPERATIONAL management ) setting up of new facilities, provide necessary information Main tasks of a DISTRIBUTION Utility Enterprise (DUE) in on land use pattern for planning optimum expansion of short-term include the operation and control of the network, and enable more systematic network operation network ensuring the security and reliability of the POWER control and maintenance.

6 For example, the route supply. Security of supply is the ability of the network to information of underground cables facilitates the meet customer demand without suffering an interruption emergency maintenance crew who will dig to reach the in the first instance, and secondly, where an interruption faulty party of the cable that exposed to a short circuit. develops it is the ability to restore POWER more quickly via Customer information database can also be included in alternative supply options. The number of customer GIS database.

7 Demand type, outage information and interruptions and customer minutes lost per connected customer complaints are among the information that give customer are common measurements of the reliability important feedbacks to ASSET management decisions. assessment today. Monitoring and tracking the ASSET Future developments of GIS technology may include SCADA processes technology. Fig. 1. FAS designed for DISTRIBUTION network of Istanbul-Turkey (TUDOSIS, TUBITAK-BILTEN). FAULT RESTORATION DISTRIBUTION system topology should be appropriate to Automation Control System (ACS), which improves the introduce such an ACS application.

8 The configuration of continuity of supply in general, has long been stimulating the network assets and communication infrastructure for the DISTRIBUTION engineers to consider it for location, the FAS described above, are given in Fig. 2. isolation and restoration of the faults occurred in DISTRIBUTION systems. ACSs are indispensable to provide reliability particularly in metropolitan cities, where the DISTRIBUTION network is sophisticated due to heavily meshed underground cable network with lateral branches to adjacent loops.

9 The design of ACSs is usually specific to DISTRIBUTION system characteristics. The Feeder Automation System (FAS), which was designed specifically to improve the reliability of electricity DISTRIBUTION system of Istanbul, the biggest metropolis in Turkey, is illustrated in Fig. 1 as an example [2]. The system operates as follows. In case of a fault at the indicated section of the feeder in the figure, the fault current is picked-up by the relays R1 to R5, but not by R6-Rn because of the radial system of operation. The circuit-breaker (CB1) at the beginning of the feeder opens and clears the fault at 1 second at most.

10 Once the fault is located by the sophisticated algorithm of the hierarchical control subsystem of the FAS, then it can be isolated from the kV substation provided that the disconnect switches at both ends of the line sections are remotely controllable. Using the same signal transmission medium, Fig. 2. Configuration and communication infrastructure of the disconnect switch at point A in Fig. 1 is ordered to the kV DISTRIBUTION transformer substation in Fig. 1. open, which makes it possible to reclose the circuit (TUDOSIS, TUBITAK-BILTEN).