PHT Project

600 kW, NY

Year: 2018
Running Gear: Three units: One vertical shaft Francis turbine with synchronous generator. One horizontal shaft turbine with synchronous generator. One horizontal shaft double-runner turbine with synchronous generator.
Scope: Replacement control system, switchgear, and HPU. Black start capability.

Located in a small town in the Adirondak mountains in upstate NY, this hydroelectric plant was built in 1904. Originally, the plant had a transmission line to a nearby town to help power the iron mine, and then later began supplying power to local houses. Sometime after World War II, the plant was connected with the local utility system, and was owned and operated by the utility until 1969, when the original penstock rusted out. The current owner established a 400kW interconnection in 1981, which was upgraded in the late 1980s when capacity was increased to 600 kW by adding a third unit.

In 2018, the dam and steel penstock deliver water to the original (but highly modified) powerhouse, where the three turbines are located, each in a separate pressure case. The three units are a vertical shaft Francis turbine with synchronous generator, a horizontal shaft turbine with synchronous generator, and a horizontal shaft double-runner turbine with synchronous generator, for a total of about 600kW. All of the control and protective equipment in use until 2018 was installed during the upgrade in the late 1980s.

In summer of 2018, PHT supplied and installed a new digital control and automation system, upgraded switchgear, and a new hydraulic wicket gate operator. New utility grade Basler BE1-11g digital multifunction relays replaced the existing electromechanical relays. New, more reliable, vacuum contactors replaced the existing oil-filled manual breakers. A new hydraulic power unit (HPU) replaced three Woodward governors, greatly reducing complexity and maintenance. Our standard recommended sensors/instrumentation were added to each of the three units, for measuring turbine speed, bearing and stator temperatures, water levels and pressures, etc. Remote access and push notifications and alarms allow the plant operator to monitor the plant remotely. Automatic level control keeps the plant running well, without the frequent trips to the dam to check the water level that were previously required.

One unusual feature requested for this plant was black-start capability. The new PHT controls, including the vacuum contactors, are powered through a large UPS. The HPU has a DC motor and battery to back up the normal AC motor. When power to the town goes out (which is frequent), the plant detects the outage, opens the Station Breaker, then runs one of the generators in off-grid mode to provide station service power, run heaters, and keep the powerhouse from freezing. The hydro plant has even been used to power the local fire station during an extended outage.



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