Evaluating Power Transfer of Transmission Lines and Proposing Power Transfer Reduction Actions to Enhance Small-Signal Stability

Small-signal stability (SSS) is one of the limiting factors for determining the power transfer capability (PTC) of transmission lines. Control centers try to optimally operate the system with the lowest probability of instability after a line outage contingency. Hence, this article proposes a novel framework to evaluate the PTC from the viewpoint of SSS, and for the violated cases, proper actions for power transfer reduction (PTR) are applied. The proposed methodology is based on a SSS optimal power flow problem. First, the proposed method identifies the stressful line by developing a novel index. Then, different dynamic parameters, which can be calculated quickly and reliably are introduced to evaluate the PTC of stressful line from the SSS viewpoint. Afterward, appropriate actions are enabled for the violated scenarios. These actions include generator redispatching and load shedding, which are exploited based on sensitivity analysis. The proposed framework not only can modify the power transfer of the understudy line, but also considers PTC constraints of other lines. The suggested scheme is evaluated on both IEEE 39 bus and 118 bus test systems. The obtained results confirm that the proposed scheme superiorly evaluates PTC and enhances SSS by applying the PTR action to preserve system security.