The increasing penetration of PV power generation inevitably leads to the decline of system inertia

posing challenges to frequency stability.To this end

virtual inertia control has been proposed; however

it causes more fluctuations of system inertia.To address this issue

a novel equivalent inertia evaluation method for multiple PV power generation under virtual inertia control is proposed.The total system inertia is first estimated based on historical or injected disturbance.Then

the total inertia of multiple PV power generation is directly calculated by subtracting the inertia of synchronous generators from the estimated system inertia.To improve practicality

a partition-based strategy is introduced

which divides the system into regions characterized by homogeneous frequency response behaviors.After partitioning

only the synchronous generator data within the region and inter-area transmission line power are required for evaluation

reducing the demand for PMU data compared to traditional methods requiring measurements at each PV connection point.Comprehensive simulation results in a 10-machine 39-bus system penetrated with multiple PV power generation validated the effectiveness of the proposed method.