In view of such power quality problems as voltage sag

low voltage

harmonics and reactive power in power grid

a kind of topological structure of back to back single phase three level uncoupled transformer is adopted which

compared with structures such as H-bridge

eliminates coupling problem between bridge arms and reduces losses and cost of equipment. At the same time

TTA algorithm at the rectifier side is adopted in this paper to detect reactive power current

which also has reactive power compensation function.As for the inverter side

the feedforward control strategy of output voltage is adopted

which eliminates the influence of load on control performance of the inverter system. At the same time

the advantage of small modulation degree of the equipment is fully used and the instant refresh mode is adopted in the DSP to eliminate the influence of control time delay

improve greatly the open-loop gain

response speed

steady-state control effect and system robustness of the system. The correctness and effectiveness of the topological structure

TTA algorithm and control method are verified by the developed 10 k VA compensation equipment.