A harmonic screening tool for capacitor applications in transmission systems

For efficient and secure operation, electric utilities are aggressively installing capacitors in their transmission systems. The techniques used to locate the capacitor banks in the system consider such issues as voltage control, losses, and contingency performance. The effects of harmonics and the resonance conditions that such transmission capacitors may create are typically not considered in the strategies employed to locate the banks unless specific circumstances dictate the need for a detailed study. Due to the large number of capacitor locations to be considered, the number of switching steps in a particular bank, and the changes in the system caused by contingencies, the number of scenarios to be studied often exceeds that which is reasonable for detailed harmonic studies. Because most capacitor applications utilize automated contingency analysis techniques such as those found in PSS/E, it is advantageous to incorporate harmonic screening into this accepted framework. The tool described in this paper can take PSS/E output files and perform the harmonic screening of the system for the contingencies of interest in a batch mode. This tool is based on standard assumptions for harmonic modeling and simulation and incorporates sparse matrix techniques in order to evaluate the larger system models common to transmission systems.