Determination of interface flow margin for voltage stability analysis using the modified continuation power flow

This paper introduces a new concept of interface flow margin in terms of steady-state voltage stability. The interface flow margin is the active power flow margin of the key transmission lines between one region and others under a fixed load demand condition. In addition, the paper proposes a technique to trace interface flow-voltage (f-V) curves by applying a continuation method. From the f-V curves, interface flow margin can be easily obtained, which is useful to determine secure flow limit of the specified interface. In the case study, illustrative examples with the New England 39-bus system and a practical 771-bus system are shown.