Development of an intelligent outage management system to improve the reliability of electricity distribution network

Abstract

The thesis presents the result of pilot project that creates an intelligent outage management System which accurately locates faults in real-time and send fault details to the relevant maintenance crew.

Several measures of reliability indices have been developed by the electric utility industry to measure system performance. The reliability of supply is governed by the frequency and the duration of interruptions to supply and the number of customers affected by interruption. An Outage Management System (OMS) will certainly help utilities identify and restore outages sooner and more efficiently. A fault affected zone in the distribution network can be isolated from the healthy part of the network by disconnecting the affected sector using Air Break Switches, Drift down Lift Off switches, (D.D.L.O) or Autoreclosers. That equipment can be used to optimize the restoring process by isolating smallest possible section of the network affected by fault. Without confining merely to an Outage Management System (OMS), this can be further developed to a supervisory control and Data Acquisition system (SCADA) that facilitate distribution automation function with communications, help to strengthen existing distribution systems and provide a strong foundation for building a fully implemented feeder scheme.

But presently Ceylon Electricity Board (CEB) which is the national utility responsible for the major portion of distribution of electrical power in Sri Lanka is not taking maximum usage of automation facility of currently available equipment. There is no proper coordination between automated equipment. Also proper automatic reporting and recording system is not available. As a result of this, expected level of reliability improvement couldn't be achieved. Hence the automatic outage program can be used to overcome above shortage.

Main objective of the project is to develop automatic outage reporting and controlling system for the North Western Province Branch of CEB, integrating all switching facilities like Auto recloses, GSM fault indicators, Non GSM fault indicators and Load break switch to improve distribution network reliability. The proposed outage management system has modern features such as Data acquisitioning from GSM fault indicators, storing the data for future analysis, indicating the fault location in network diagram, Generating the massage automatically and sending to nearest crew, and Capable of handling data base files.

Since North Western Province has very complicated electrical network, Thulhiriya - Kuliyapitiy feeder which has large number of transformers and having long length is selected as pilot project considering distribution indices such as System Average Interruption Duration Index (SAIDI), System Average Interruption Frequency Index (SAIFI) using past outage data of year 2008 and 2009. Based on SynerGEE software reliability data, the locations to install new GSM type fault indicators, Non GSM type fault indicators were identified. So 10 number of GSM type fault indicators, 20 number of Non GSM type fault indicators, 08 number of DDLOs, were installed.

The outage management system was developed using Visual Basic 6 for usage of at the Distribution Control Centre. Then program was installed in the control centre and executed for six months. Then the reported break down was compared with break down history of the feeder and Financial Feasibility Analysis was done. It was observed that the initial investment is paid back within first four years which indicates the implement of the Outage Management system is financially feasible. Also the significant improvement of reliability could be observed.