Time domain modeling of constant power loads for electromagnetic transient simulations

Abstract

This paper proposes a dynamic constant power load offering constant active and reactive power and constant power factor suitable for electromagnetic transient simulations. The proposed model is agnostic to the frequency components of the system because it is developed in the time domain. The proposed model returns current and voltage quantities imitating the behavior of either inductive or capacitive loads. The model is customized so that it can be solved using readily available numeric solvers, such as branch-and-bound algorithms. The bottleneck of the computational speed depends on the numeric solver that is employed to solve the proposed model and the hardware used to process the computations. Also, convergence to a solution (an issue associated with every solver) is more likely to occur if the optimum initial solution is provided, which is left for future research. The model is validated using constant impedance load data. In this work, 2500 data points were simulated, and the output shows that the proposed model is accurate, and any approximations can be attributed to the adopted numerical differentiation method. The model is computationally exhaustive; thus, its application is limited to small systems.