Transmission system planning considering integration of renewable energy resources

The penetration level of renewable energy generation has been increasing in some actual power systems, and hence introduces some new problems and even challenges for transmission system planning. In modern transmission system planning, it is necessary to consider the accommodation capability of renewable energy generation, in addition to the traditional requirement for power system reliability. Given this background, a bi-level transmission system planning model is presented for this purpose with transmission investment costs, load shedding costs, abandoned wind power costs as well as relevant operating constraints considered. In the upper level, the objective is to minimize the sum of annual investment cost and the expected value of annual economic loss of shedding load and wind energy abandoned for given scenarios. In the lower level, the objective is to minimize the sum of economic loss of shedding load energy and wind energy abandoned for each scenario. These two levels are implemented interactively and iteratively, and the optimal transmission system planning scheme will ultimately be attained. The upper level model is described as a mixed-integer optimization problem, and solved by the well- established particle swarm optimization algorithm; the lower level model is formulated as a linear programming problem, and solved by the linear programming solver ILOG CPLEX. Finally, the essential characteristics of the proposed models and adopted algorithms are demonstrated by a modified 18-bus sample power system.