Coordinated Planning of Renewable Energy and Grid Expansion Based on Scenario Trees

The uncertainties of renewable energy bring challenges to the grid planning. The existing method is to linearize the variables directly in the expansion planning problems considering uncertainties. This will result in decreasing accuracy and multiple solutions. This paper applies the scenario tree method to improve this situation. First, it analyzes the limitations of conventional optimization methods and precious studies. Then it establishes a renewable energy planning model with the objective to minimize the total cost. This model considers renewable energy and line construction comprehensively, and it chooses a typical day of each prospective year including several scenarios. Then the model calculates the total costs of generating electricity and evaluates the hosting capacity of renewable energy under multiple constraints. Those constraints include the system safety constraint, the programming variable constraint and the scenario-based renewable energy constraint. Finally, this model is applied to the IEEE 57-bus test system. The results demonstrate that renewable energy and line allocations play an important role in reducing the total costs, and rational allocated lines are significant in promoting the hosting capacity of the renewable energy in the system.