1.2 MW, MN
Running Gear: 3- generating units: Two vertical shaft synchronous generators, each driven by a 33-in Leffel B propeller turbine. One propeller driven induction generator.
Scope: Replacement control system.
This 1.2MW hydroelectric project is located at a dam in Minnesota that was originally built in the late 1800s to supply mechanical power to a mill. By 1896, the project was abandoned. The current owners of the project, the City in MN where the dam is located, bought the dam in 1911 and installed hydro power generators in a new powerhouse. The hydroelectric plant has been in operation ever since, with periodic repairs and upgrades.
In 2016, the powerhouse includes 3 turbine-generators. The first two are vertical shaft synchronous generators, each driven by a 33-in Leffel B propeller turbine. The third is an induction generator, driven through a gearbox by a propeller turbine. This third unit was added in the mid-1980s. The switchgear and excitation for the two synchronous generators were updated in 2003.
PHT was hired to provide a new control system for Units 1 and 2, and to provide start/stop signals to existing Unit 3 controller.
The new control system, installed in the summer of 2016, replaced the existing manual controls with a modern PLC and touch screen. The PHT system controls some of the existing equipment, including the existing switchgear and exciters, as well as adding more modern instrumentation. PHT replaced the existing battery operated wicket gate HPUs with AC powered units with accumulators. PHT supplied two new Basler BE1-11g generator protection relays, as well as additional sensors; including water level, trash rack level, tailwater level, temperatures, vibration, oil level, and speed. This project also required integration of the new control system for the hydropower plant with the City water department SCADA system. Like all PHT systems, the new PHT control system allows the plant to be monitored and controlled remotely, and for plant personnel to receive push notifications.
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