Power system modeling in Modelica for time-domain simulation

Considerable progress has been made in recent years on the development of common formats for the exchange of power system data. However, no such common format exists for the exchange of mathematical models. The objective of this paper is to explore how a model of an entire power system could be described in an open modeling approach. A requirement of this approach is the possibility to describe a model without establishing input/output relations. The proposed method is based on the use of the modeling language Modelica, an equation-based language which allows acausal modeling. Additionally, Modelica has an important capability of conveniently modeling discontinuities. To illustrate the method, a small but complex system is implemented using a Modelica model and subsequently simulated by a generic differential algebraic equation solver. Results are compared with those obtained from a power system simulation package.