Analytical studies on power system dynamic stability enhancement by doubly-fed adjustable speed machine

Doubly-fed adjustable-speed pumped storage generating systems of large capacity have been newly installed in power systems with technologies of power electronics. These new generating systems contribute not only to frequency regulation of power system at nights by means of input power change as results of rotor speed control, but also to enhancement of power system stability by fast control of voltage and power. New analytical method based on extended Heffron-Phillips model was developed in order to support design of a power system stabilizer which is used to improve dynamic stability of the synchronous generators located in the vicinity of the doubly-fed generating system. A systematic approach based on the new analytical method is shown with numerical examples, explaining how to design the additional power system stabilizing controller of the doubly-fed generating system.