Multi-level Evaluation Index System and Application of Grid-Connected Performance of Grid-Forming Energy Storage Converters

To evaluate the active support capability of grid-forming energy storage converters, a set of quantitative evaluation index system is proposed to evaluate the performance and effectiveness of the current mainstream converter control strategies. Firstly, from the perspective of voltage and frequency stability, the characteristics of power, voltage, and frequency under multi-time scales are observed. Considering the power support density and energy support density, a set of quantitative evaluation indicators system for the three-level performance of "single machine-substation-grid" is proposed. Then, based on the Matlab/Simulink simulation platform, a single-machine infinite system model of the energy storage converters based on grid-following (GFL) and grid-forming (GFM) controls is built, and the proposed single-machine side indicators are analyzed and calculated. And a large-scale power grid model in the Southern Xinjiang region is also built based on the DIgSILENT simulation platform to verify the effectiveness of the proposed field station side and grid side indicators. The research findings demonstrate from the perspective of indices that the GFM control has better support capabilities than the GFL control. The proposed evaluation index system can provide a reference for field testing of GFM energy storage system demonstration projects and selection of location and capacity for GFM energy storage stations.