Fast frequency evaluation using direct current loadflow

Frequency evaluation is an important but time-consuming task for power system operation. Conventional frequency response analysis methods were not suitable for fast frequency evaluation (FFE) due to their weakness in heavy computation load or poor accuracy. A new direct current loadflow based power system frequency response analysis method (DFR) for FFE was proposed in this paper. It reduced complexity of models by neglecting the impact of reactive power-voltage dynamics on active power-frequency dynamics. Generating units were simplified by adopting the assumption of constant terminal voltages while the network was simplified with direct current loadflow. An example of Fujian power grid in China was given to verify the usability of DFR in FFE. Simulation results show that the new method can reflect frequency dynamics with adequate accuracy and low computation load.