A Comparison of Multivariable Time- And Frequency-Domain Design Methods for Power System Stabilisers including Links with Reported Field Trials

The paper describes a comparison of multivariable, frequency-domain and time-domain design methods to derive supplementary stabilising signals for a highly oscillatory electrical power system. A direct comparison of different multivariable design approaches is effected on the same power system for the first time. The direct Nyquist array (DNA) method is extended in its application to produce practical stabiliser structures not previously obtained by other multivariable design approaches. All of the controllers designed have been implemented in practice including the DNA extension which produces a stabiliser requiring the measurement of machine terminal quantities only. The different theoretical approaches are also shown to produce essentially the same stabilisers and this, combined with their practical realisability, is a unifying result which is both satisfying and worthwhile emphasising.