Research And Design Of Distribution Static Synchronous Compensator Based On H-bridge Cascading

The Reactive power compensation is the main method to improve the power quality of the power grid,and plays an important role in ensuring the safe and stable operation of the power grid.With the increasing industrial load in the distribution network and the access of a large number of power electronic equipment,the nonlinear load and the impact load pose a serious threat to the stability of the distribution network.Therefore,the reactive power compensation of the power grid system faces a new challenge.Considering the economics,pressure resistance and reactive power compensation capacity of the compensation equipment installation,the subject has extensively reviewed the literature and analyzed the reactive power characteristics of the distribution network,and determined that the cascaded H-bridge DSTATCOM is the research object.The compensation performance of the compensator is studied in terms of circuit structure,mathematical model,control method and simulation verification.The research results show that the device has the advantages of good scalability,large compensation capacity,strong pressure resistance and small output harmonics.The specific research contents of the project are as follows:Firstly,the circuit structure and working principle of the three-phase cascade H-bridge DSTATCOM are introduced.By comparing the characteristics of the star-connected and angular-connected circuits,the star-shaped structure is selected as the main topology and the H-bridge sub-module works.State,equivalent mathematical model and switching modulation method are studied,and carrier phase shift single-stage frequency doubling modulation is selected as the modulation method of the circuit;Secondly,in order to realize the stable control of the circuit system,the voltage-current double closed-loop control strategy based on feedforward decoupling is studied,and the current prediction control module and the capacitor voltage equalization control module are designed to optimize the dynamic effect of the control system.Thirdly,according to the characteristics of the distribution network design circuit,the DSTATCOM simulation model of the three-phase three-cascade H-bridge for 10 k V distribution network is built by Matlab/Simulink software,and the simulation is verified by the above theoretical analysis.The simulation analysis shows that: cascade The H-bridge DSTATCOM can realize the dynamic compensation of the reactive power of the distribution network,and its compensation speed is fast,the precision is high,and the harmonic content is low;Finally,the theoretical research work and the simulation verification process in the subject are summarized,and the conclusions of the research are obtained.The problem of the lack of experimental data support for the research process is proposed,and the future work prospect is put forward.