The continuous increase for people dependency on electrical energy to run most of their industrial, commercial and residential activities makes it necessary to regularly improve the distribution systems. This Improvement does not involve served area and system capacity increase only, but also includes service quality and system reliability enhancement.

Outage is the most serious challenge that might affect the reliability of the distribution system, especially in the congested areas like New York City, where the outage is a threat for continuity of service for a large number of customers or for the important world institutions there. Outage incident in distribution networks normally leads to onerous financial losses as customer reimbursements and faulty equipment fixing or replacement.

Accumulation of unrepaired secondary open main incidents causes a network deficiency especially in high load season due to the limited available paths to deliver customers loads. Most of times, such situations overload some network equipment that put the correspondent protection devices in action and eventually cause outage incident. Consolidated Edison Company of New York maintains a reliable distribution system in one of the biggest cities, the occurrence of limited outage incidents during the last years makes it essential requirement to implement an automatic open main detection mechanism as possible causer for some incidents to protect the system reliability from same events in the future.

This novel study presents an effective detection system for open main and transformer outage incidents using statistical approaches. Based on periodic network transformers loads readings provided by Remote Monitoring System (RMS), any transformer load change exceeds the normal load change boundary will be listed as suspect event to be analyzed. Sensitivity analysis is implemented in this study based on the actual real time transformer load changes and pre-calculated values for transformer load changes for each expected incident in the network. The calculated values can be obtained using power flow program (Poly Voltage Load Flow PVL).

Transformer outage sensitivity analysis is implemented on the suspect event taking into consideration the load response at most nearby transformers. According to this part results, open main incident sensitivity may be launched to confirm or banish the open main incident depending on the response of near by transformers. Those transformers can be determined as the most affected nearby transformers according to pre-calculated values for each possible open main location.

Eventually, detailed report supported by chart plots is issued to identify the nature of the incident (is it transformer outage or open main incident), to indicate the transformer or the main at which it took place and to list the real time load changes for all the network transformers included in the sensitivity analysis. All of that to facilitate an immediate repair of the faulty part and to easily investigate the incident root causes to be avoided later and eventually improve the distribution system reliability.