Voltage-dependent models of power generation units: A detailed analysis for control center application

Presently, the reactive power limits of the power generation models implemented in the TSO´s system security assessment tools do not respond to the voltage magnitude. This may lead to overoptimistic results in high load situations with low grid voltages. This paper proposes a voltage-dependent model of power generation units with detailed consideration of internal synchronous machine effects. The model has been implemented in a professional power flow tool and tested thoroughly. It is then compared to a full dynamic simulation with the help of a test grid. It is shown that the power flow with the proposed model yields positive margins and is thus suitable for control center applications.