Control method for improving power grid stability of hybrid energy storage system

The invention relates to a control method for improving the stability of a power grid of a hybrid energy storage system, which comprises the following steps of: forming a double-closed-loop control structure by adopting outer loop voltage control based on droop characteristics and inner loop power control based on improved model predictive control (MPC), controlling an energy storage converter, the droop characteristic of the system is utilized to generate an inner loop power reference value through an outer loop, and the trend of preventing direct current voltage change is achieved; the inner ring is a power ring and is used for tracking a power reference value generated by the outer ring, calculating a predicted value through a prediction model, and selecting a switching state corresponding to the predicted value closest to an expected value to act on the energy storage converter; and designing power prediction models in two working modes of Buck and Boost, and constructing a target function according to a