The Collierville facility, located in Vallecito, California now has a new agreement with CA ISO to provide, rather than purchase, megawatt regulation and reserve, said NCPA technical supervisor Sandy Rainey. ‘Additionally, units are operating 24/7 and are no longer started and stopped daily,’ added Rainey. ‘This method of operation has reduced unit thermal cycling issues and provided much improved generation reliability to our members.’
The upgrade began in June 2001, when GE Energy replaced the existing plant controls with a triple modular redundant (TMR) system, integrating the turbine control and programmable logic controller (PLC) needle sequencing functions into a single digital control.
In 2003, GE and NCPA developed a qualification plan to meet the CA ISO load requirements. CA ISO, a not-for-profit public benefit corporation, manages the flow of electricity along California’s open-market wholesale power grid. Engineers constructed a turbine non-linearities model and created the correction parameters that could shift the load rate within CA ISO requirements.
‘Using correction parameters in the controller algorithm allows the turbine load change rates to be consistent, regardless of where the turbine is operating,’ said Ricardo Artigas, president of energy services for GE Energy.
In March 2003, NCPA personnel performed CA ISO Ancillary Service qualification testing, which resulted in each multiple needle impulse unit at Collierville to qualify for CA ISO ancillary service markets. This allowed NCPA to offer a wider range of products and gain a greater return on investment.
Entry into the market also allowed for the implementation of an improved operating plan that reduced maintenance costs.
