Based on statistical concepts, Power Balance (PWB) method is used to estimate the magnitude of electromagnetic energy in electronic system under high-frequency interference. Its effectiveness has been preliminarily confirmed, while its flexibility and convenience are attractive features. In this paper, the generalization of network formulation based on PWB method is presented in details which makes Computer Aided Analysis (CAA) be performed easily. Moreover, a practical application in a dual-cavity system is illustrated. The comparison of results obtained from PWB method and full-wave analysis method shows that PWB method can indeed provide effective data that meet certain accuracy requirement with much smaller computational cost than full-wave analysis method.