Design of dynamic voltage restorer based on improved strong tracking filter algorithm

With the massive access of new energy and nonlinear and asymmetric loads, the power quality problem in the power grid has become increasingly prominent. Voltage sag problem is one of the serious power quality problems often encountered in power system. As a common voltage sag control device, the dynamic voltage restorer has improved the voltage detection mode and control strategy of the dynamic voltage restorer. Aiming at the traditional strong tracking filtering algorithm’s judgment of voltage sag detection, the filter divergence threshold is set very small, There will be a greater probability of fading factor and filter gain adjustment, which will eventually lead to unsmooth system state estimation. In order to quickly and accurately detect voltage sag characteristics,. A voltage sag detection method based on improved strong tracking filtering algorithm is proposed. On the basis of considering the influence of harmonics, DC offset, non integral harmonics and noise, an improved strong tracking filter model including DC components, fundamental and harmonic components is established. At the same time, proportional resonance control is used to replace the commonly used proportional integral control. The simulation results show that the improved dynamic voltage restorer has stronger robustness and higher compensation accuracy.