Siemens Energy, together with A&N Electric Cooperative and RuggedCom, Inc., has successfully deployed an ultra high-speed distribution feeder automation (DFA) system that improves service reliability for the only hospital serving the eastern shore of Virginia, Riverside Shore Memorial Hospital in Nassowadox, Virginia. The combined smart grid DFA solution allows for optimized fault detection, isolation and restoration, minimizing the extent of power outages by quickly isolating affected areas.
The Siemens distribution feeder automation-decentralized (SDFA-DC) system achieves high-speed operation by detecting faults using Siemens SIPROTEC protective relays located at each feeder section point -- continuously comparing upstream and downstream line current conditions. When a comparison reveals a differential exceeding predefined parameters, the affected relay issues a fault notification to all other relays in the system. The relays then direct switching devices to reconfigure the feeder, isolating the fault and transferring viable line sections to another substation power source when necessary.
System communications are handled by standard WiMAX wireless links consisting of RuggedCom's RuggedMAX base stations and subscriber units. Before commissioning, Siemens and RuggedCom engineers determined that WiMAX's wide bandwidth and near-line-of-sight propagation characteristics would provide an ideal communication platform for critical, high-speed feeder automation applications.
"Because Riverside Shore Memorial Hospital is so critical to our community, we needed a way to reduce the impact of outages caused by numerous automobile collisions with our pole lines. The SDFA-DC distribution feeder automation system from Siemens meets our needs by detecting faults, isolating problems, and transferring to alternative power sources in less than half a second," says Kelvin Pettit, vice president of system reliability at A&N.