In September 2009, a tsunami hit the island of American Samoa, destroying the Satala power plant - one of the main power generation facilities on the island - and leaving the isolated, Pacific community with an 18MW power shortfall.
Emergency relief efforts were supported by the United States Federal Emergency Management Agency (FEMA) and a temporary system was deployed. About one year later, the American Samoa Power Authority (ASPA) issued a request for proposal (RFP) for a temporary power generation system to provide 18MW of continuous, reliable electric power to operate for approximately two to three years until the Satala power plant could be rebuilt.
The RFP requested a flexible, modular system that could be redeployed after the Satala plant was completed. It specified using ISO-certified containers for component packaging to ensure easy handling, installation and relocation. In addition, it required a flexible configuration with the ability to operate as two sites with up to eight generator sets, as an independent system, as one large combined system, and with or without being in parallel with the existing utility grid.
The power plant needed to meet the demands of a tropical location and include a comprehensive Supervisory Control and Data Acquisition (SCADA) system to provide local and remote monitoring and control capabilities. Finally, the entire power plant had to be fully functional within eight months or risk significant financial penalties for missing the deadline.
Cat dealer Hawthorne Power Systems partnered with Enercon Engineering to provide a detailed bid that included design and engineering information, system configuration and optimisation, and site implementation and planning. Hawthorne was the primary contractor, providing the generator sets, project management, logistics, and site installation labour and co-ordination. Enercon Engineering served as a sub-contractor, providing the custom container fabrication, packaging, switchgear and controls, fuel tanks, SCADA system and testing.
The system design called for 11 Cat 3516C diesel generator sets rated at 1,650kW each at 13.2kV and 60Hz. The 3516C gensets are EPA Tier 2 compliant and run on ultra low sulphur diesel fuel to minimise emissions. To meet the specifications of the RFP, each generator set is housed in a custom-built stainless steel container. Built by Enercon Engineering, each 40-foot (12.2-metre) cube container meets ISO and CSC specifications and is fabricated from specialised, selected grades of stainless steel to provide superior corrosion resistance.
The design of the containerised generator sets is based on a traditional, rental-fleet power modular concept and includes local switchgear and paralleling controls in each unit to provide the ability to operate individually or as a group. The two line-ups of main switchgear - one for each site - are also housed in custom-built, stainless steel, 40-foot (12.2-metre), ISO-certified cube containers and are configured so that each can easily be relocated to meet application needs.
Each generator set is connected to one of the two main line-ups of switchgear through a disconnect switch in the switchgear and the individual local paralleling circuit breaker. These main line-ups also each feature a utility tie breaker, several feeder breakers and a bus tie breaker. The main switchgear line-up also features a PLC system to gather and process system information through communications and input/output modules. This control system is fully compatible with the existing monitoring system and can control the generator sets remotely. The SCADA system compiles information from all system components and creates a seamless interface for monitoring and control.
Once all equipment was fabricated and shipped to American Samoa, Hawthorne sent a team to install the plant. Hawthorne was responsible for all aspects of the installation, including site erection, fuel system piping, control and low voltage interconnect wiring, and final commissioning of the system. ASPA performed all site preparatory work and all medium voltage cabling. Once the plant was installed and startup completed, a 14-day continuous run acceptance test was completed prior to turning plant operations over to ASPA. Turnkey installation and commissioning were completed in less than two months.
From the original RFP phase to the final commissioning process completed in late June 2011, this project allowed ASPA to partner with the Hawthorne and Enercon Engineering teams to design, construct and implement a fully integrated system for a tropical marine environment on a remote island in the Pacific. Innovations and ideas produced and implemented on this project can be used by other power authorities to help them provide reliable, efficient power generation solutions to their areas.
Enter √ at www.engineerlive.com/ipe
Joel Martin is with Caterpillar Inc, Mossville, Illinois, USA. www.catelectricpowerinfo.com/pr