parallel carry
5.We analyze the multiplication procedures and find out the obstacles to improve the speed. To accelerate the multiplication operation, a modified Booth structure has been used to reduce the number of partial products. And Wallace tree structure with LRCF (Left-to-Right, Carry Free) algorithm has been applied to make the addition of partial products and carry propagation in parallel.
6.Firstly, an index to assess the power system transient risk is put forward, based on the additivity of this index the huge calculation tasks of figuring out the critical clear time (CCT) of fault are assigned to the nodes of PC cluster to carry out parallel calculation, then the comprehensive risk index of whole power system is obtained by collecting the results of parallel calculation in coordinator of the PC cluster.

