AC and DC filter capacitor banks in China generally use H-bridge structure

but some converter stations use π-type structure capacitor banks

and the off-line test method for unbalanced current of H-bridge capacitor banks is not applicable any longer. In this paper

a new method of indirectly measuring unbalanced current is proposed by forming a π-type capacitor bank into an H bridge. And the method derives the calculation formula and simulates such three methods of forming the H bridge as resistance

capacitance and inductance. For reducing the influence of on-site electromagnetic interference on the measurement accuracy

the method of testing unbalanced current at multiple frequency points is used for on-site testing. The results show that the theoretical idea of the new method is correct and can accurately measure unbalanced current.