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

A new concept of interface flow margin in terms of steady-state voltage stability is introduced. 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, a technique is proposed to trace interface flow-voltage (f-V) curves by applying a continuation method. From the f-V curves, the interface flow margin can be easily obtained, which is useful to determine the secure flow limit of the specified interface. In the case study, an illustrative example with the New England 39-bus system is shown.