Rapid Recovery of Voltage Sag in Distribution Network Based on Dq Transformation

This paper proposes a real-time voltage compensation method based on dq transformation by simulating three-phase voltage. With A, B and C phases as reference, the phase locking method of second order generalized integrator is used to measure the three-phase voltage phase. The three phase alternating current is established respectively, and the corresponding Ud and Uq are obtained by abc-dq transformation. When the voltage dropping, the Ud corresponding to the single phase voltage will drop, so that keeping the Ud value at the rated value (Ud at the rated voltage of the grid), and the voltage drop can be quickly recovered. The energy of the DC unit of the inverter is rectified by the auxiliary winding of the transformer. When the voltage sag occurring, the corresponding voltage compensation is given by the single-phase inverter, which can keep the original amplitude of the grid voltage. The simulation model of the circuit is established by MATLAB/SIMULINK. The three-phase voltage drop is simulated in the simulation circuit, and the load voltage waveform and the output voltage waveform of the inverter are simulated in the case of the drop. The effectiveness of the proposed method is verified by observing the load voltage waveform after compensation.