RENEWABLE ENERGY DRIVES GT SALES

LMS100 ORDERS THRIVE ON CALIFORNIA’S ENVIRONMENTAL REGULATIONS

Gas turbine OEMs are targeting the renewable energy market with machines that can respond quickly to match the total load demand of fluctuating renewable power while maintaining grid stability. GE Energy’s LMS100, in particular, is finding broad application in areas such as California, which boast high renewable portfolio standards. Nineteen of the first 54 LMS100s have been sold to customers in California, which has issued a goal requiring that 33% of electricity come from renewable sources by 2020.

“Gas-fired generation is our only means right now, until storage and demand response have matured, to compensate for the fluctuations of wind and solar power,” says California Independent System Operator (CAISO) spokesperson Stephanie McCorkle.

The LMS100 is said to provide greater capacity than aeroderivatives but faster start times than frames. It startswith the low-pressure compressor from the Frame 6FA IGT, runs the air through an intercooler, and then into a supercore (HP compressor, high-pressure turbine and intermediate-pressure turbine) based on the LM6000. Using the intercooler to lower the temperature of the air going to the high-pressure compressor reduces the work of compression, resulting in a 42:1 pressure ratio and increasing the flow mass to 460 lb/sec.

To reduce NOx emissions, LMS100s come with either water injection (the LMS100 PA) or dry low NOx (DLE) combustors (the LMS100 PB), and both models produce a 25 ppm NOx emission. The LMS100 PA has 103 MW output and the PB 99 MW (100 MW for the 50 Hz version). The PB has a lower heat rate — 7,695 Btu/kWh compared with 7,815 Btu/kWh for the PA.

All LMS100 models offer a 44% efficiency rate, ten-minute start times and 50 MWper minute ramp rates, making them suitable for peaking and load following operations. They also meet the needs for base load power generation, giving power producers greater flexibility in their system design.

Technology that lets you start, synchronize and meet full load in short time frames modifies spinning reserve requirements, says Joseph Camean, VP and Director of Power and Utility Engineering Services for Van Zelm, Heywork and Shadford. Spinning reservemarkets typically require that the turbines be fired up and able to synchronize with the grid within ten minutes. With the LMS100, however, no spinning is required, since they can black start and synchronize within that time frame.

Connectiv Energy, for example, a subsidiary of Pepco Holdings, which owns 20 generating stations in five Middle Atlantic States, has started specifying LMS100s so it can participate in PJM Interconnection’s voltage support and reserve markets. PJMis a regional transmission organization that coordinates the movement of wholesale electricity in several states.

Greater Flexibility

Power markets require turbine owners to have greater flexibility, providing black start, spinning reserve, base load and voltage support when needed. One way to achieve this flexibility is with a synchronous clutch. The clutch allows the turbine to bring the generator up to speed and then disconnect so the generator stays connected to the grid, operating as a synchronous condenser to provide voltage support while the turbine can shut down until it is needed to provide peaking power.

The first LMS100, installed at the Cumberland Station in Millville, NJ, includes an SSS Clutch between the generator and turbine. “Asynchronous condenser is connected to an electrical system and absorbs leading reactive power fromthe supply system when over-excited, and supplies VoltAmperesReactivewhen under-excited,” says Morgan Hendry, President of SSS Clutch. “A synchronous condenser at the load-end of the line can produce the precise amount of reactive power required.”

California’s first four LMS100s went on line in Firebaugh in 2009. Five units owned by Competitive Power Ventures went on line in August 2010 and they have three on line in May 2012. Edison Mission Group has five units going on line in June 2013.

Utilities are also getting into the act. The Los Angeles Department of Water and Power has engaged in a $2.4 billion, multidecade project to replace all its generators that use ocean water for cooling. Instead of replacing the gas fired boilers, Units 5 & 6, with a large frame GT, the LADWP decided to go with six LMS100s, so they can control output in response to renewable fluctuations. The units can be started one at a time or all together, going from 0 to 600 MW in ten minutes.

“If we had a 600 MW power block, we would have had a big jump of 300 MW,” says John Dennis, LADWP’s Director of Power System Engineering. “These can be run all the way up to the 600 MW and any kind of increments in between.”

Now, with the older steam turbines, they could be left online at minimal load and the generator would provide necessary voltage support. Since the LMS100s would be offline when not in use, LADWP took the same approach as Connectiv and installed an SSS clutch on two of the new units.

“During slow periods, we could go all that way down to zero generation and just keep the generator synchronized and acting as voltage support to the system,” says Dennis. “This gives us greater overall flexibility and replaces the old technology that took so long to start up.”

The equipment is now being installed at the LADWP Haynes plant, and it is on target for completion in time for the 2013 summer season. The second repowering project, the Scattergood Generating Station near the Los Angeles International Airport, is scheduled for completion in 2015.