Abstract: The uncertainty of the new energy represented by wind power and photovoltaics in the new energy high penetration power system makes it difficult for the thermal power units to meet the accuracy requirements of the dispatching plan. In order to improve the accuracy of the thermal power unit dispatching plan, a day-ahead optimal dispatching strategy is proposed for the thermal-storage-load systems in a new energy high-penetration power system considering variable time period control. First, the Gaussian mixture model is used to cluster the net load into those in three types of time periods according to the time series characteristics. Then the variable time period control rules of the thermal-storage-load systems are designed according to the characteristics of each time period to optimize the day-ahead scheduling. The demand response is used to optimize the utilization rate of the pumped storage power station. Second, aiming at the minimum total system costs, a thermal-storage- load scheduling model is established by comprehensively considering the constraints of various types of units formed by the proposed strategy, and a day-ahead scheduling plan of thermal-storage-load is formed. Finally, the effectiveness of the proposed strategy is verified by an example analysis.