Calculation of dynamic security region based on electrical distance and the dynamically equivalent of unit coupling coefficient

The expansion of the power system makes that the analysis of the power system transient stability has to spend much more time computing. The development of dynamic security region (DSR) provides an effective method to solve this problem. After the introduction of dimension reduction techniques, not only it ensures dynamic characteristics of the system unchanged basically, but also the dimension of the system reduces obviously and the computing time of DSR reduces significantly. In the process of reducing dimension, the choice of the system has a major impact on the accuracy of dimensionality reduction and the speed of calculation. This paper covers four aspects: firstly, it proposed a expanded concept of electrical distance; secondly, based on the expanded concept of electrical distance, the paper propose a new partitioning method.; thirdly, the paper put forward a new method, use the probability of unsafe indicators to evaluate the accuracy of dimensionality reduction, more realistic; besides all above, different scale of the dimension reduction simulation results from the model validate the proposed reduced-partition method, which is reasonable and effective.