This paper proposes an individual phase current control method based on optimal zero sequence current separation for star–connected cascade STATCOMs under unbalanced grid voltage. The Individual phase current control (IPCC) is adopted to get better adaptation to unbalanced conditions. Each cluster of the cascade STATCOM has its own phase current control loop and dc voltage feedback loop, and it can generate the necessary negative sequence current automatically to rebalance power. However the zero sequence current which is unnecessary and harmful in star configuration is introduced in the process. An optimal zero sequence current separation (OZSCS) is presented to remove the zero sequence current, by reconstructing the reactive current command. This improved IPCC enables star–connected STATCOMs adapted to unbalanced conditions without the need for any power balancing algorithms. Also the operation range of the proposed control method is analyzed. Simulation researches are performed to verify the operation range analysis, and experimental operation is tested on a 25-level ±10Mvar/10kV STATCOM product installed at a wind farm.