The stochastic and variable characteristics of high proportion of renewable energy in the future power system would bring unprecedented challenges to power system operational flexibility

rendering specialized planning for flexible resources in power system indispensable in the whole planning process as never before. An overview on power system flexibility planning technique considering high proportion of renewable energy is given. Firstly

the features of power system with a high proportion of renewable energy are analyzed. Then the definition of power system flexibility

the main flexible resources in power system and the flexibility equilibrium are given prior to demonstrating current research on quantitative evaluation of flexibility. Finally

the core content

key technical problems and solving approach in power system flexibility coordinated planning are proposed. This work is supported by National Key Technologies R&D Program(No. 2013BAA01B03)and State Grid Corporation of China(No. SGTYHT/14-JS-188).