Multi-year and multi-state distribution systems expansion planning by multi-stage branch exchange

This paper proposes an algorithm for solving a problem of multi-year distribution systems expansion planning in which severe fault cases(mu1ti-stage) are taken into consideration. In the algorithm, the multistage branch exchange algorithm is applied to make the solution accurate, and the decomposition co-ordination method is introduced to make the algorithm efficient. An N-years distribution planning problem is decomposed into N single-year planning problems each of which is decomposed into several planning problems to find a feasible radial feeder configuration according to predetermined severe fault cases. So as to co-ordinate these decomposed problems, so-called forwardlbackward-path procedure is applied. The validity and accuracy of the proposed algorithm are demonstrated by several numerical examples through comparing the calculation result with the ones by conventional methods.