This paper presents a new scheme of controlling inter-area oscillation consisting of WAC and CIA index as controlled islanding criteria. For this purpose, based on the WAMS, the correlation factor between all SGs pairs are calculated which the coherent SGs are determined. In this case, by identifying two oscillating areas, the inter-area oscillation is evaluated in COI frame which uses as the GIS through the proposed WAC scheme. Also, for estimating the IDR, a RD technique is proposed which by evaluating GIS signals through consecutive time windows, the signals IDRs are evaluated. In the case of identifying an unstable IDR, by evaluating the GIS signal and identifying the GIS zero crossing points ZCPs as the CIA tripping index, the corresponding emergency action (islanding/damping) is determined. The proposed approach is an online and non-model-based scheme which by evaluating GIS signals through consecutive time windows, the system dynamic securities and emergency actions are provided. The effectiveness of the proposed scheme is evaluated on the IEEE 39-bus system with indicating positive effects through damping the inter-area oscillation.