The traditional frequency response reserve planning involves the inertia in primary frequency regulation (PFR) resources

which fails both to meet the system inertia demand under the new situation and to realize the joint planning of inertia and PFR reserve. Meanwhile

neglecting the decision maker's risk preference may lead to homogenized patterns of extreme eventsand lay potential security threats. A joint planning method of inertia and PFR reserve considering extreme events is proposed. The system frequency response model with multiple types of source-storage-load regulation resources is established. The system disturbance set is obtained by using sequential Monte Carlo probabilistic production simulation. The penalty model is constructed to measure the loss of rate of change of frequency (RoCoF) overrun. The frequency stability probability index is proposed to characterize the probability distribution and loss expectation of frequency limit violation. The cost benefit model of reserve with risk preference is developed for collaborative planning and allocation of multiple flexibility resources

and the feasibility of planning solutions is verified. Based on the improved IEEE-RTS79 case studies

it is demonstrated that the proposed method can flexibly formulate the optimal planning under different risk ranges according to the decision maker's risk preference

providing a more targeted decision-making basis for improving the new power system's response capability to extreme events.