With the acceleration of the pace of global energy transformation, the proportion of renewable energy generation continues to increase, and the volatility and uncertainty of the power system also increase, which puts higher requirements on the flexible adjustment ability and stable operation of the power system. Therefore, this paper reviews the key role of energy storage system (ESS) in assisting the operation control of new power systems and its optimal configuration technology. Firstly, the application scenarios of the energy storage system in the aspects of peak regulation, frequency modulation and power quality improvement are systematically reviewed, and the optimal configuration strategy of the energy storage system under these application scenarios is deeply discussed. Secondly, the economy, reliability and stability of energy storage optimization are analyzed and studied in detail. Then, the advantages, disadvantages and applicability of different optimization algorithms (including linear programming, dynamic programming, genetic algorithm, particle swarm optimization, etc.) are compared. Finally, the challenges and future development direction of energy storage optimization configuration technology are revealed. The analysis shows that scientific and reasonable allocation of energy storage resources is crucial to improve the operating efficiency, stability and reliability of the power system, and is a key technical approach to promote the wide application of renewable energy and achieve the goal of smart grid construction. In the future, with the development of new composite energy storage technology and the introduction of intelligent optimization algorithms, energy storage optimization configuration technology is expected to play a more prominent role in the sustainable development of new power systems.