System to use non wind driven doubly fed asynchronous machines to improve inertial response characteristics

摘要

The DFIG (doubly fed induction generator) or DFM (doubly fed machine) (1, 2) is enhanced to run in synchronous compensator mode. The DFIG or DFM rotor frequency is controlled using controller (13) and back-to-back converter (7, 9) and DC Link (8), which control the speed of the machine. Unlike traditional synchronous compensators, this invention can provide programmable sustained response while retaining dynamic response by changing its rotor frequency and its reference synchronous speed. Recovery of kinetic energy can be achieved through a controlled programmable ramp rate while always retaining a dynamic response capability even during recovery. Additional embodiments of the invention include an additional shaft mounted flywheel (3), optional DC from vacuum flywheel can be used to support the DC Link (11), optional fluid turbine (10) for additional sustained response (which can also be used as a starting device), xDFM (4) option or permanent magnet exciter, and a starting device (for example, by either direct drive or converter from mains). The doubly fed machine can be run up to within approx. 70 percent of its synchronous speed using a form of starting device (for example, by either direct drive or converter from mains). When the machine is at approx. 70 percent of synchronous speed, it is possible to connect to the grid (5) in a soft starting manner. Figure 1