Control of D-STATCOM for Asymmetric Voltage Dips Compensation

The variable frequency drive (VFD) is sensitive to distortions at the point of common coupling (PCC). Decreasing of the voltage at the PCC for more than 50 ms leads to the shutdowns of VFD and breaks the process. As a result, it leads to emergency situations, defects and under-release of products. The VFD of rolling mills, gas pumping compressors, stations for maintaining reservoir pressure and other powerful electrical equipment are sensitive to voltage dips. The phenomena of a voltage dip often caused by short circuits or starts of a powerful load. Often short circuits accurse in one or two lines and lead to asymmetric voltage dips. The article describes the D-STATCOM control method to compensate for asymmetric voltage dips, although usually D-STATCOM is used to reduce symmetrical voltage dips. The obtained analytical expressions for solving the inverse problem of determining the voltage of a series-connected compensator show the possibility of using it to compensate for voltage dips.