Application Of Cascade Static Var Generator SVG For High Voltage

With the rapid development of social economy,the scale of power system is becoming larger and larger,and the types of loads carried by power grid are also increasing.The operation of a large number of unbalanced and non-linear loads seriously affects the power quality of power grid.In this paper,based on the project of power quality,aiming at the phenomenon of short-term reactive power impact in steel production line,which causes the voltage fluctuation and low power factor of power supply system,the SVG with H-bridge cascade structure is studied and designed,which is suitable for high-voltage and high-power fields.Firstly,in this thesis,the development status of reactive power compensation devices are briefly introduced;advantages of cascade structure be highlighted,the strategy of cascaded SVG be introduced.Meanwhile,the principle of SVG reactive power compensation is introduced,the mathematical model of cascaded SVG is established,and the detection algorithm of reactive current is proposed;The good harmonic characteristics of the carrier phase shift modulation technology are verified by simulation;Based on the mathematical model,the current decoupling control method is proposed,and the DC voltage balance strategy based on hierarchical control is studied.The effectiveness of the proposed scheme is verified by comparing the former and the latter by Matlab/Simulink software.At the same time,the parameters of the main circuit are calculated and selected.The hardware circuit of the cascade SVG control system and the software system based on DSP+FPGA are designed.Finally,this thesis takes the cascaded SVG device applied in the medium profile production line of Masteel as an example,combined with the theory of reactive power compensation,through parameter calculation,on-site debugging and monitoring,the results show that the cascaded SVG device has good dynamic effect after being put into the steel rolling production line,which can quickly compensate reactive power,improve power quality,and maintain the power factor at about 0.95,which can play a good role in the improvement of Power quality effect.