As the proportion of renewable energy in the power system continues to increase, the inertia level of the system gradually decreases. Utilizing energy storage to provide inertia and primary frequency support for photovoltaic generation has become an effective means to address frequency stability issues. Parameters for frequency support that are too small cannot fully utilize the frequency modulation capability of optical energy storage systems, while parameters that are too large will lead to active power output limits of inverters during transient processes. In response to this, the paper proposes a method for optimizing the inertia and primary frequency modulation parameters of optical energy storage systems, taking capacity limitations into account. First, based on the control equations of the grid-type optical energy storage system, the analytical relationship between frequency deviation, frequency deadband, primary frequency modulation coefficient, and inverter output is established to derive the feasible boundaries of the primary frequency modulation coefficient to ensure that the inverter and energy storage output do not exceed limitations. Secondly, with the constraints of optical energy storage system capacity limitations and the dynamic equations participating in transient frequency support, an optimization model for maximizing the frequency nadir of the optical energy storage system is established to determine the optimal virtual inertia coefficient. Finally, simulation analysis verifies the effectiveness of the proposed frequency support parameter optimization method.