Finally, the generator may be of the doubly-fed induction machine type, also known as a wound-rotor induction machine, where a back-to-back VSC is connected between the rotor and stator windings. This allows control of the reactive power from both the rotor and supply side converters, with a reduced converter rating. Again the machine speed can be controlled as well which enables peak power tracking or adjustment of the real power output. However, the cost of the machine is greater than the case of a squirrel Cage induction machine and therefore, the additional controls come with an additional price. Compression of advantages and disadvantages are shown in Table .