Dynamic voltage restorer against balanced and unbalanced voltage sags: modelling and simulation

This paper presents modelling aspects of several types of dynamic voltage restorer (DVR) working against various voltage sags by simulation in PSCAD/EMTDC. It then provides analyses of working performance of the device, including capability and quality of compensation. Comparisons of working performance among these different types of DVR are also addressed. Significant simulation results show that these several types of the modelled device can work very well against balanced and/or unbalanced voltages caused by faults in a distribution system. Detailed analyses illustrate that with suitable parameter setting these devices can deal with different levels of voltage sag severity. In addition, appropriate ways to obtain a good quality output voltage by a DVR during voltage sag is also presented.