Load modeling with considering frequency characteristic

Accurate load model plays important role in power system analysis. Voltage is the only input of traditional load model. It is different to continuously match the electrical output of generating units to the electrical load in some special power systems or Micro-grids which have a weak grid structure. In such a system, frequency will fluctuate severely when fault occurs as well as the voltage. Therefore, both the characteristic of voltage and frequency should be considered in the load model. Based on the traditional composite load model, a new load model with considering frequency is presented. Under new definitions of the practical variables of induction motor, the voltages behind the reactance are redefined as the linear equations of flux linkage. Ant colony algorithm is used to estimate the key parameters of the new model. Simulation results show that the improved load model is effective and accurate under the system fault with severe frequency fluctuation.