An improved modal analysis method for harmonic resonance analysis

This paper analyses harmonic resonance of the system with branches containing independent constant voltage source. Harmonic resonance often manifests as high voltages in a power system. It was found that such resonance phenomenon is associated with the singularity of the network admittance matrix. The singularity, in turn, is due to the fact that one of the eigenvalues of the matrix approaches zero. By analyzing the characteristics of the eigenvalue, one can find useful information of the resonance. Modified nodal method must be used to construct nodal matrix of the network for the system containing independent constant voltage source branch. Based on the results, an Improved resonance mode analysis combining modified nodal method with mode analysis to construct nodal matrix of the network is proposed. Analytical and case study results have confirmed that the proposed method is a valuable tool for power system harmonic analysis.