Whether the STATCOM can withstand the impact of grid imbalance

perform stable operation and provide effective dynamic reactive power support in the case of grid imbalance is direct embodiment of its performance.In this paper

the control method of negative sequence voltage feed forward and zero sequence voltage stability of cascade STATCOM is proposed staring from the point of the balance of suppressing negative sequence current and active power and with the use of superposition principle.The negative sequence is suppressed by way superposing negative sequence component at the port voltage of inverter.Superposition of zero sequence component in the port voltage of inverter to offset the positive sequence reactive power current and the active power due to the negative sequence component of port voltage of the inverter

thus achieving stability of the three-phase DC voltage.The method can deal with the influence of the negative sequence voltage on the device in the grid fault

avoid DC voltage instability of the device in grid fault and

at the same time

can compensate accurately dynamic reactive power.The strategy proposed in this paper finally passed Matlab/Simulink simulation test and RTDS test.