With the expansion of the scale of the distributed power generation system

its adaptability to the grid after grid connection has become a key technical problem

especially on how to perform effective voltage support to the grid after the fault in different grids. As for this issue

the flexible voltage support and control strategy of a kind of distributed power inverter at grid fault is proposed in this paper. The flexibility of the control strategy

unlike the traditional power grid support and control scheme

is reflected in the voltage improvement per phase by way of injecting reactive power in case of three-phase voltage balance sag

control of voltage balance

elimination of negative sequence component of voltage and reduction of phase mutation in case of one phase or two-phase asymmetrical fault. The test platform is set up

and test research of voltage support and control at two types of power fault is developed. It is shown by the test result that at the support and control strategy of new type of flexible voltage the grid voltage is effectively supported after the fault and the control strategy is verified.