Improved Direct Power Control of PWM Rectifier under Unbalanced Network based on new Power Reactive Estimation

The direct power control (DPC) for PWM rectifier is the right candidate for the high performance control to offers a unit power factor, a low rate of harmonic distortion of the currents absorbed by the rectifiers and good regulation and stability of the DC bus voltage. However, the DPC based on a conventional switching table is severely deteriorated and the line currents are distorted when the grid voltage is unbalanced. To overcome these drawbacks, we have proposed an improved DPC control technique using a new definition of instantaneous reactive power which can achieve sinusoidal network currents and constant active power without using an extraction of the complicated sequences. In order to regulate both the active power and the new reactive power, a new switching table is established. Thus, the simplicity and robustness of conventional DPC are maintained through the use of this new definition of reactive power. Numerous numerical simulations under Matlab/simulink were presented to confirm the theoretical study and the efficiency of the proposed control method.