Computation of electrical equipment load behavior regarding to frequency variations in isolated grids

In operation of isolated grids, switching of large loads can cause significant frequency oscillations, which influence the power consumption of grid coupled electrical machines. This reaction in power consumption is based on a superposition of the quasi-stationary and dynamic effect, whereby the quasi-stationary effect is mainly related to the torque-speed characteristic of the working machine and the dynamic effect is caused by the mass inertia. In the course of this paper, the influence of characteristic parameters on the load frequency dependence, mathematical equations and diagrams for an estimation of the effects pertinence as well as a methodology for modelling the load frequency dependence are displayed. Furthermore, the relevance of the load response to frequency deviations on the total system is demonstrated.