The use of switching functions and Walsh series to calculate waveform distortion in thyristor controlled compensated power circuits

Abstract

A new model based on the Walsh series for assessing the steady state operation of three-phase thyristor controlled reactors (TCRs) is presented in this paper. The model represents the TCR as an admittance matrix which interfaces easily with other power plant components in the network. Clearly, the admittance matrix representation is not confined to Walsh domain but rather it is valid for any orthogonal approximation of functions having the operational properties used in this paper. However, the switching functions which characterise the operation of TCRs are better represented by the Walsh series and they have been used in this paper. This is a new development in power systems analysis. Other orthogonal series expansions such as Fourier series and Hartley series have been used elsewhere. The Walsh transform possesses the important operational properties of the product, coefficient and integration matrices. The relevant aspects of the interaction between the TCR and the electric network are analysed. A three-phase TCR and a transmission network represented by a Thevenin equivalent are used for this purpose.