The present invention provides a system and method for representing quasi-periodic waveforms comprising, representing a plurality of limited decompositions of the qp waveform, wherein each decomposition includes a first and second amplitude value and at least one time value. Each wind energy installation includes a generator which is driven by a rotor, and the wind farm master includes a power control device having a plurality of loops. An installation instrument is also disclosed for removable attachment to implant and engagement with the rotatable insert to selectively permit rotation between the insert and the support body.