In order to protect the system against loss of synchronism or inter-area oscillations, the system operator has to conduct a large number of short-term stability studies. Transient stability focuses on phenomena in the range of the ms and depends mainly on the active component models - synchronous machines and their controllers, HVDCs, Static Var Compensators.

To properly represent the system response in the few instants following an event, it is necessary to combine open models with detailed physical modelling and transparent block control scheme with a very accurate solving method. It is the association of these different features that enables to catch the correct system fast dynamics.

DynaSwing is a simulation tool that offers an unique combination of a transparent, flexible and robust way of modelling - thanks to the intensive use of the Modelica language - and a state-of-the-art, efficient and accurate numerical method (the variable time-step solver IDA).

The core of the tool has already reached a mature state, making it usable for running transient stability studies, as visible in our use cases documentation The future work will thus concentrate on:

• the development of more elaborated regulation controls (PSS, specific governors or voltage regulators);
• the addition of new models (especially standard PV and wind models);
• the improvement of the numerical method on large test cases (especially on systems containing a lot of digital controllers).

These developments will contribute to enlarge the possibilities offered by DynaSwing.