PHT Project

6.4 MW, Jamaica

Year: 2014
Running Gear: A single high-head Francis turbine and synchronous generator.
Scope: Replacement of existing control system

As of 2014, the sole electric utility on the island of Jamaica operates eight hydroelectric stations, in addition to the oil and diesel powered stations, and a small amount of wind that power the island. In 2011, PHT was selected to replace an obsolete control system at a 1.2 MW hydroelectric site. In 2014, PHT was again hired to provide new controls to replace the aging system at a 6.4 MW site.

This 6.4 MW site is the largest hydroelectric plant on the island. While the running gear is in excellent condition, the controls were becoming infeasible to support, and did not provide the functionality and the utility needed to operate the plant effectively. PHT provided a new control system with new hardware, including a PLC, touch screen, generator protection relays and Payne exciter.  The existing hardware digital governor system and excitation controller systems were replaced with a much simpler software systems running inside the PLC.

The PLC provides multiple excitation control modes to meet this customer’s requirements: features include Voltage Regulation, Power Factor and Reactive Power modes, and a reactive power capability curve limiter.  This system is generator-fed to allow black starting, and so requires sequencing of field flashing as well.  The new governor and excitation controls greatly improve plant usability, by replacing the difficult to use “black boxes” with easily monitored and adjusted subsystems within the single user interface.

The control system is also designed to operate via remote control from the adjacent, brand-new hydro station located at the same site.  The neighboring system is able to monitor and control the PHT control system over a fiber optic Ethernet link.  This allows all three generators located at this site to be operated from a single control system interface.

As usual, PHT designed and built the control system at our facility in NC, and then shipped to the site in Jamaica, where PHT staff traveled for on-site installation and commissioning.

This is the second project completed by PHT for the electric utility on the island of Jamaica

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