Dynamic protection and security assessment for highly loaded power systems

The paper presents the application of software tools to simulate system dynamic behavior together with the possibility to select critical contingencies of an electrical energy system. The protection system, which is connected to the primary system via vts, cts and trip contacts, is running in parallel during system simulations, with all necessary relay functions, characteristics, settings and communication schemes. Possible visualization methods are presented which can support the operators to select critical system states-either of the primary or the protection system. Insecure operating conditions can be monitored in the time domain using the full system representation in real time or by calculating the eigenvalues of the system to monitor weakly damped system states and stability margins. Warnings about unselective protected areas can pop-up for fast information or they can be shown with the corresponding relays in single-line diagrams as a basis for new necessary protection coordination study. The locations of short circuits with corresponding trip times and unselective trips or no trips can be monitored in two-or three-dimensional diagrams. The optimized settings can be directly transmitted to relays, which are able to receive the adaptive settings.