Network equivalents and expert system application for voltage and VAR control in large-scale power systems

This paper presents an application of the steady-state network equivalents and an expert system for voltage and reactive power (VAr) control in large-scale power systems. A steady-state network equivalencing technique is used to construct the "three-tier" subsystem which is adequate to solve voltage violation problems. An expert system utilises the sensitivity tree method to select the optimal set of control actions to alleviate the voltage problem. The expert system was developed using the VP-EXPERT system shell. VP-EXPERT interacts with the power system analysis software providing analysis of the network sensitivity matrix and data for the knowledge base. Practical application of the developed expert system is demonstrated on the example of the Hydro-Electric Commission (HEC) power system of Tasmania, however the proposed approach is not limited by the system size.