A joint optimal clearing model for energy, inertia and ramping in power systems considering multiple time scales

In order to ensure the stability of a high percentage of renewable energy systems, it is equally important to procure new types of inertia and ramping resources in addition to the use of traditional frequency regulation and standby services. However, there is little research on inertia and ramping in the existing power market, much less consideration of the coupling between energy, inertia and ramping. In order to fill this research gap, this paper not only considers the strong coupling relationship among the three, but also involves multiple time scales, and proposes a joint clearing model of energy, inertia and ramping that accounts for multiple time scales. Firstly, the trading volume of inertia in the medium and long-term market is determined based on historical data, the shortage of inertia in the spot market is determined based on the frequency safety constraints, and the system ramping demand is determined in combination with the predicted output of the system for the next time period. Secondly, a market clearing model is constructed, with the bilateral matching principle used in the medium and long-term market, and the spot market being cleared by a joint clearing of energy, inertia and ramping. Based on the specificity of inertia, this paper uses the continuous start-stop state Lagrange function to find the shadow price of each resource. Finally, a case study and comparison show the advantages of the proposed model for improving the stability and economy of the system.