A Norton approach to distribution network modeling for harmonic studies

This paper presents a Norton approach for modeling distribution networks where the system configuration is not fully known. Traditionally, harmonic studies use complex distribution networks modeled by harmonic current sources for specific frequencies. Although this approach has been proved to be adequate for some studies, this may not happen for other applications. When changing the operating condition of the supply-side system, the harmonic currents injected by the distribution network might change. This information is in this paper used to estimate a Norton model of the load-side distribution network. The estmated models can be used to analyze, for example, the effect of harmonic filters under different supply system configurations or operating conditions. The method of estimating the Norton models is illustrated on a test system, simulated on the well-known simulation program EMTDC. The performance of the estimated models is, for different configurations of the supply system, compared to the performance of the traditionally used “constant current” approach.