The paper suggests integrated impedance based intelligent relaying for thyristor controlled series capacitor (TCSC) compensated transmission lines. The scheme uses a new relaying signal termed as imaginary part of integrated impedance (IPII). Integrated impedance is defined as the ratio of sum of the voltage phasors across two ends of the transmission line to the sum of the current phasors through two ends of the same transmission line. IPII of each phase of the transmission line is used as input to a data mining model known as decision tree (DT) which selects the faulted phase(s) involved in the fault process. The scheme is validated on Real time digital simulator (RTDS) platform. The test results obtained indicate that the proposed IPII based intelligent relaying is reliable in protecting of extra high voltage (EHV) transmission lines including TCSC. © 2014 IEEE.