Investigation of the effect of the insertion of series capacitors in high voltage transmission lines on the settings of distance protection

Series capacitors (SCs) are commonly installed on long transmission lines. The benefits gained include: (i) an increase in the magnitude of power that can be transferred over the line, (ii) improvement in power system stability, (iii) reduction in losses over transmission lines, (iv) improvement in voltage control, and (v) having the possibility of a more flexible power flow control. However SCs and their overvoltage protective arresters can disturb the measurement process of line impedance made by distance protection (DP). Consequently to ensure that protection relays perform properly in the presence of SCs the latter should be taken into account when the setting of such relays are calculated. This paper investigates the effect of the insertion of SCs on the settings of DP normally installed on transmission lines