Harmonic modeling in power distribution system using time series simulation

Abstract

Harmonic distortion is one of the major power quality concerns. The non-linearity of customer loads caused the occurrence of harmonic distortion that leads to degradation of power system components. Therefore, harmonic studies have become an important part in power system modeling, simulation and analysis. The needs for harmonic modeling and simulation are to determine the existence of dangerous resonant conditions and to verify that the distortion level complies with the standard harmonic limits. This research is to model time-series harmonic analysis. An integration of Open Distribution System Simulator (OpenDSS) with Microsoft Visual C++ and Microsoft Excel into an application for time-series simulation control is presented. Harmonic power flow analysis is performed by using OpenDSS interfaced with C++ to simulate the time-series simulation. The impact of practical harmonic loads measured from commercial, industrial and residential sectors on different distribution network systems are investigated. Two test case studies, with and without harmonic loads are modeled to show the usefulness of time-series simulation. IEEE test feeder and practical power distribution system are used as the test system for both case studies. The impact of harmonics on the test systems is studied by using the measured harmonic data obtained from logging sites. The simulation results were compared with the standard harmonic limits to ensure the compliance of distortion levels. Simulation results obtained show that total harmonic distortion has a significant effect on the losses of the system, mainly on the lines, cables and transformer losses. The losses of the system with harmonics for both types of the test system showed an increment compared to the system without harmonics. Hence, this proves that when harmonics exist within the system, losses increase. Based on the simulation results acquired using the developed application, the system losses and the level of harmonic distortions in the electric power distribution network are easily obtained for each interval of time-series. The developed application saves computational time as well as providing a method that is cost effective.