Three-Phase Dynamics Simulation of Power Systems Using Combined Transmission and Distribution System Models

This paper presents a new method for studying the electromechanical transients in power systems using combined Transmission and Distribution (T&D) models. Unlike the traditional dynamics analysis techniques which assume a balanced electric network, the methodology presented in this paper models individual phases of the power system and associated imbalances in load and generation. Therefore, the impacts of load imbalance, single phase distributed generation and line impedance imbalance on electromechanical transients can be studied. Although other existing software can also be used to study electromechanical transients in unbalanced networks, such software model electric networks through differential equations, which makes the study of large electric networks time consuming. Thus, the methodology presented includes imbalance modeling and overcomes the system size limitations of existing software tools, providing the means for studying electromechanical transients in large, unbalanced T&D systems. The implementation of this methodology in software is called the Three Phase Dynamics Analyzer (TPDA).