Bi-level Collaborative Expansion Planning for Power Grid and Plants Considering Operational Flexibility

The penetration of large-scale renewable energy such as wind power requires increasing improvements of operational flexibility of power system to handle undesired uncertainties. However, operational flexibility enhancement should be located in a holistic framework including both generation and grid side. In this paper, the global operating margin containing reserve, ramping and transmission ability is used to describe operational flexibility facing the uncertainties. Based on this, a bi-level collaborative expansion planning model is proposed to provide the appropriate solution of generators retrofit and transmission lines enhancement. The upper model forms the network line extension decision considering investment constrains. The lower model calculates the site and capacity of thermal power units based on the new network from upper layer. KKT condition are used to transform the bi-level model into MILP problem. The effectiveness and feasibility of the proposed planning model are proved by the simulation of an actual power grid case.