Multivariable Frequency Domain, Time Domain and Practical Approaches for the Derivation of Stabilising Signals in Electrical Power Systems

The paper looks at multivariable frequency-domain and optimal control design methods for the derivation of supplementary stabilising signals in electrical power systems. The emergence of different approaches to the design problem are examined and shown to produce the same results if used correctly. In the past the inverse Nyquist array method (INA) has produced different results because the problem posed was changed, in some cases, to fit the perceived theory. Finally, after consolidating the different approaches, the direct Nyquist array (DNA) is extended in its application to provide a practical stabiliser design that has the added advantage of dependence only on measurements at the generator terminals. This enables the same device to be applied to any generator without custom-tailored hardware development.