A heuristic approach to solve multistage transmission expansion planning

The consideration of uncertainties in the future system operation is a key aspect in current planning methodologies. Cost-effective transmission expansion planning (TEP) is a major challenge with regard to electrical power system optimization problems. The main purpose of solving the TEP problem is to obtain the optimal expansion plan for an electrical power transmission network. Furthermore, TEP should specify the newly required transmission facilities that must be added into an existing network to provide adequate system operation and performance to meet the increasing load growth over a specified planning horizon. Contingency selection involves advanced estimation of contingencies which are most likely to cause limit violations. In this work DC load flow is used for contingency analysis purpose to monitor reliability and security constraints. Optimal lines are added by using Heuristic methods i.e., forward search method and backward search method for the case when the system is not acceptable for normal and N-1 line out condition. YBus is modified for each contingency and each line addition. The screening method is based on approximate power flow solutions to eliminate the non-critical contingencies. DC load flow screens the least contingent lines in combination with the power flow calculations. The method has been tested on 5 bus Graver system and 46 bus Brazilian transmission systems.