Quickest detection of short-term voltage instability with PMU measurements

The quickest detection of short-term voltage instability in a smart grid is considered. The problem is formulated as a binary sequential composite hypothesis testing where the null hypothesis is a non-stationary process with an unknown exponentially decaying mean and the alternative is a nonstationary process with an unknown exponentially increasing mean. A sequential generalized likelihood ratio test (SGLRT) is proposed and analyzed. It is shown that the proposed SGLRT is asymptotically optimal.