In this paper a new technique for estimation of distribution network load model parameters based on PMU measurements data and Harmony Search Algorithm (HSA) is proposed. Distribution network loads reveal some complicated behavior as these networks are connected to distributed generations(DG) such as fuel cells or wind turbines which implements modern electrical machines. Therefore, the conventional models of the distribution loads should be modified to overcome this problem. In this paper the load model and its relative equations has been modified. Estimation of the double fed induction machine(DFIM) parameters and load power-dependability to network frequency change are included in the model. The proposed model is simulated in Matlab/Simulink software under some normal and abnormal conditions of the network.