T&D World Magazine

Hawaiian Electric Company Cites Under-Frequency Protection as a Key Benefit of Direct Load Management Program

Hawaiian Electric Company, Inc. (HECO) is implementing a system-wide direct load management program that will provide a solid foundation for reducing peak electrical demand and provide its customers new choices for reducing electricity costs. The company was also interested in an important feature embedded in the control devices manufactured by Cannon Technologies, Inc.: Line Under-Frequency (LUF) automatic protection.

Since HECO is an island utility without any interconnection to the national grid, the LUF protection feature built into Cannon’s load management receivers is important to the utility. The feature turns each managed load into a real-time safety valve that will instantly react to power system instabilities by shedding load. The feature can be adjusted and enabled remotely through the communication link. Control events are generally signaled by the utility through paging communication, but the LUF feature works locally and independently at each load connected to the load management receiver to be effective at combatting frequency problems—which can occur instantly and without warning.

The HECO program targets water heaters on the island of Oahu. The program’s primary purpose is to allow HECO to operate reliability with smaller reserve margins, but customers will also benefit from fewer outages related to frequency droop events.

Keith Block, manager of the Residential Direct Load Control Program explained, “Island networks are particularly susceptible to under-frequency problems due to the closed nature of the system. Without the ability to draw on reserves from neighboring utilities, frequency will decline any time one of our generating units unexpectedly drops off-line. While not every frequency decline will trigger the load management receiver, Cannon’s LUF devices will be an important tool in preventing outages caused by under-frequency events.” He added, “We have already seen the LUF feature perform in a small frequency droop last month; it works just as we intended.”

Joel Cannon, president of Cannon Technologies adds, “It’s nice to see utilities valuing the advanced protection features of our load management devices. We have offered LUF in receivers for a long time, but its value is more evident now as distribution systems are under more stress.”

The LUF feature adds significant added value to the system at an extremely low incremental cost, when the control units are already being installed for demand reduction purposes.

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