Sensitive Voltage Differential Protection Method for Transmission Lines Compensated with SC

New solar PV and wind generation farms are usually connected to the grid through existing transmission lines, while remote generating plants may be connected through newly constructed long transmission lines (TLs) with limited capacity. In both cases, the power transfer capability of the TLs can be increased by introducing series compensation. Introduction of the series capacitor (SC), however, complicates the protection of the TLs rendering the traditional distance protection ineffective. The literature reports on numerous schemes that are grounded in innovative principles for protection of TLs with series compensation. However, most of the techniques are designed for application with specific compensation points along the line - near end, mid-point or far end. The use of a sensitive voltage differential (SVD) algorithm for the effective protection of a transmission line regardless of the placement of a fixed series capacitor, is suggested in this paper. The algorithm generates a sensitivity-based fault detection index whose magnitude depends on changes in the magnitude and phase of the voltages at the SC and line terminals. The performance of the suggested scheme is evaluated through extensive DigSilent PowerFactory simulations, and the results show that the scheme is sensitive to faults over 100 % of the series-compensated TL and is effectively independent of fault resistance.