MICROTURBINE POWERED GENERATOR TECHNOLOGY ASSESSMENT: DIRECT-DRIVE HIGH-SPEED VERSUS DIRECT-CONNECTED LOW-SPEED

An assessment of the different technologies reveals that the selection of the optimum generation/power-control technology for microturbine generators requires the consideration of a myriad of factors. The study presented is based on extensive experience with the design, manufacture, and field operation of a 250kW direct-connected, low-speed microturbine powered generator. High-speed generators and power electronics for the same engine are examined considering impact on performance, installed cost, reliability, and flexibility. Although general improvement is expected, there are certain challenges that must be addressed before the benefits of advanced power electronics and high speed machinery can be exploited. These challenges increase with increased power demand. Higher efficiencies are not only an energy/cost saving exercise, but essential due to increased thermal stress at larger power ratings and higher electrical frequencies. Future trends of technology, manufacturing, and materials are also presented. In the final analysis, it will be prudent to carefully select a technology which ensures that the advantages of microturbines are optimized rather than compromised.