System variable evaluation with digital signal processors for SVC applications

The practical implementation of digital signal processors (DSP) is illustrated by describing a voltage regulator which is used to control a static VAr compensator (SVC). Extensive transient network analyser tests showed that signal processors used for system voltage evaluation yield results that are entirely equivalent to those obtainable by analogue methods. Digital methods necessarily and inevitably involve the sampling of analogue variables. Characteristics of the data sampling system must be taken into account at the design state. This applies to analogue signal bandwidth limitation, analogue to digital conversion, accuracy and the measures required to handle the extra delays involved. The digital implementation is described from the standpoint of the most important system value, i.e. the system voltage. In addition to processing the system voltage, digital technology is also used for reactive power calculation, synchronization voltage filtering, frequency measurement and the evaluation of system voltage for protection purposes