To cope with the problems of insufficient inertia support capacity and flexible adjustment of resource shortage caused by high proportion of new energy access to the power grid in the future

it is necessary to fully consider its ability to provide inertia support when planning a new pure pumped storage power station or transforming a traditional hydropower station into a hybrid pumped storage power station. Therefore

this paper proposes a capacity planning method for the integration

transformation

and joint construction of a conventional hydropower system with a pure pumped storage power station. While dealing with the complex working conditions of a mixed storage power station and reducing the construction cost of a pure storage power station

the system inertia demand is taken into account to ensure its economic and safe operation. Firstly

the operation simulation is used to obtain the planning year data

and the minimum inertia demand of the system that satisfies the frequency security constraint is calculated using typical data from both the high flow period and the low flow period after clustering. Secondly

the joint planning and modeling of the hybrid pumped storage power station and the pure pumped storage power station for hydropower transformation are integrated into the minimum inertia demand of the system

yielding preliminary planning results that minimize the total cost. To ensure that the planning scheme can effectively address the uncertainty of new energy

the scenario method is employed to optimize the configuration results

thereby meeting operational requirements under various conditions. Finally

the example analysis demonstrates that the collaborative planning of the two can effectively reduce the construction cost of the pure pumped storage power station and enhance system flexibility

while ensuring that the system's frequency index remains within a reasonable range after disturbance.