Research On Three-phase VSI Cascade Chotovoltaic Grid-connected Inverter And Control Strategy

In recent years,the environment problem has become a common scene,to use the clean energy is the theme of the time.Different from the traditional two-voltage converters,the three-shunt VSI PV converters are more excellent in voltage,switch frequency,voltage changing rate,THD as well as the electrical magnetic disturbance.Comparing with the H bridge,the three-shunt VSI circuit has less switches,besides,the DC capacitor current would be lower too.The model predictive control method is more flexible than the other technologies.Based on the three-shunt system target,the math model is established according to the topology.And the model predictive control method is applied in the three-shunt VSI system.Aiming at the computing complex situation in the MPC control procedure and the predictive current delay problem,the current feedback block is also added into the control system.Finally it is verified in Simulink.According to the three-shunt VSI topology,the math expressions of the three-shunt VSI circuit output voltage and current are presented.The VSI anti-inductance current is computed to the AC side of the converter in filter circuit,in this way the equivalent circuit model is established.Each part of the VSI has the asymmetric capacity in AC side,however,the holistic system is symmetric.As for the three-shunt VSI PV generation system model predictive technology,the distributing predictive model is set up under the ?? coordination,and the predictive function is established too.Moreover,to solve the existing delay problem,the periodic prediction and the phase angle compensation method is used.To solve the computing problem,the procedure of the control system is simplified,and the capacity is still in a good level.Finally,the current feedback compensation MPC control method is applied in the VSI,and it is verified in Simulink,the result turns out to be appropriate.