Abstract: The high-voltage transformer-less battery energy storage system (BESS) adopts the concept of cascading H-bridge circuits to connect the high voltage power grid. A large number of battery cells are separated equally into numerous clusters at the DC side of H-bridge submodules, and a high degree of modularity features the BESS. Compared with the low-voltage solution, it has obvious advantages such as larger capacity of single-machine, higher efficiency, and faster response speed. If the high-voltage transformer-less BESS also has reactive power compensation capabilities and can realize the four-quadrant operation of the system, greater cost advantages and economic benefits will be obtained. When the system operates at a high proportion of reactive power compensation, the structure of the battery cluster connected to the single-phase H-bridge converter results in that the battery current will reverse in a cycle of twice the fundamental frequency. The battery is charged and discharged with high frequency, which will have a great impact on battery life and battery status monitoring. To solve this problem, this paper proposes a high-proportion reactive power compensation control based on zero-sequence voltage injection and the charged and discharged current with twice the fundamental frequency is removed. Besides, the amplitude and phase of the zero-sequence voltage are optimized to minimize the impact on the battery.