Modelica-based virtual power electronics laboratory
Power electronics is a complex field, which needs inputs from various fields of electrical engineering, system theory etc. To simplify the understanding of such a complex interdisciplinary subject, computer-aided analysis and design tools are necessary. In addition to being multi-domain, power electronic systems are event-driven and usually involve both analog and digital components. Hence a simulator used for studying these systems needs to have capabilities to handle events, deal with hybrid, mixed-mode systems and support multi-domain modeling. Moreover such systems being very complex, it is desirable to have modularity on the modeling level, enabling reusability of models. This is possible if object-oriented modeling environments are used. The object-oriented modeling language Modelica allows convenient, component-oriented modeling of complex physical systems. Models are hierarchically decomposed into sub-models. The reuse of these models is facilitated by libraries containing model classes and by the use of inheritance. Parent objects namely 'TwoPin', 'ThreePin' and 'TwoPort' etc. are extended to develop various other models. Most of the models developed in the area of power electronics are derived as child objects from these parent objects. Various models used in power electronics systems like switches, firing circuits etc are also developed. These models are validated according to well-known basic power electronic topologies. The simulation results are compared with those obtained from a standard industry grade simulator SABER, thus validating the models. Measurement templates models for average, RMS, harmonic distortion etc are also developed. These templates are very useful in studying power quality issues. The sequence component-measuring template can be used to design controllers for mitigation of unbalance in power systems. These templates along with the power system library viz. ObjectStab, in Modelica developed at Lund university provide a complete tool for analysis of various power systems issues integrated with power electronic converters as is understood under FACTS devices.