In 2005, Jersey Central Power & Light (JCP&L), a subsidiary of Akron, Ohio – based FirstEnergy Corp., initiated a project to identify protection system improvements that could be made to proactively combat wind- and lightning-related weather events that create sustained power outages (Figure 2). JCP&L determined that these changes had the potential to improve the System Average Interruption Duration Index (SAIDI) reliability metric by as much as 45 minutes annually.
2. Keep the lights on. Jersey Central Power & Light has successfully reduced the number of outages caused by wind and lightning with an innovative SCADA scheme. Courtesy: Jersey Central Power & Light
Like many utilities, JCP&L operates a large installed base of electromechanical (EM) and microprocessor-based protection relays in its substations that are complemented by line reclosers on its distribution system. JCP&L’s 3,200-square-mile territory, with 1,100 circuits, services 1.1 million customers (Figure 3).
3. Center of power. Jersey Central Power & Light’s Red Bank Distribution Substation. Courtesy: Jersey Central Power & Light
Customer research indicated that reducing the number of momentary outages on blue-sky days drove higher levels of customer satisfaction, while momentary outages during storms generated minimal customer dissatisfaction. With that information JCP&L set out to devise a protection scheme that limited the number of sustained outages resulting from temporary faults during storms.
One of the first obstacles encountered was the inflexibility of the current system, specifically the limitations of the EM relays installed in JCP&L substations. The utility recognized that although each was equipped with two timing curves, delay and instantaneous, these timing options were only selectable locally through dedicated cut-off switches wired to the units (Figure 4).
4. Simple concept. SCADA electromechanical relay/adaptive relay scheme. Source: Jersey Central Power & Light
New system concept
Wanting to improve customer satisfaction, and recognizing its significant investment in installed EM relays, JCP&L’s challenge was to develop a system that could change relay timing settings proactively in response to real-time weather information. A solution was prototyped in early 2006 using a series of relays and intricate wiring tied into the supervisory control and data acquisition (SCADA) system. The solution was a relatively simple rewiring job in the substation panels, but the potential payoff was significant: a projected reduction in SAIDI of 25.1 minutes annually, if deployed systemwide.
The next phase of the project was to find commercially available products to meet the application requirements, such as field-tested reliability, SCADA compatibility, feedback capability to confirm operation, a local target display, operation at 48 or 125 VDC, and the ability to expand to control more than one breaker installation. The company wanted the components to interface not only with the EM relays, but also with microprocessor-based relays from several different manufacturers that were in use on the system, in a cost-effective manner. Electroswitch, of Weymouth, Mass., was selected to supply a variation of its two-position Series 31 Tagging Relay (TR).
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