On the Way to Integrate Increasing Shares of Variable Renewables in China: Experience from Flexibility Modification and Deep Peak Regulation Ancillary Service Market Based on MILP-UC Programming

China has declared ambitious carbon emission reduction targets and will integrate increasing shares of variable renewables for the next decades. The implementation flexibility modification thermal power units deep peak regulation ancillary service market alleviates contradiction between rapid capacity growth limited system flexibility. This paper establishes three schemes two price rules simulation proposes an analysis framework unit commitment problem based on mixed-integer linear programming to evaluate policy mix effects. Results confirm promoting effects integrating illustrate diverse scheme selections under different curtailment. Particularly, there is no need selecting expensive which contain more modified developed flexibility, unless curtailment decrement compulsorily stipulated or worth added cost. Similarly, results also prove revenue loss compensation effect rule intervals. Price with subdivided load intervals bigger differences among them effective, especially higher requirement rate. Therefore, government should further enlarge via but not targeted price, while generators consider a demand-based investment.