The Study Of Relationship Between Inverter Interfaced Distributed Generation Control Strategy And Power Quality

As the rapid development of community economy, the problem of energy crisis becoming more and more obvious and the development of distributed generation faster than ever before. The photovoltaic and wind power generation applications are required by grid connected inverter, the power quality of power grid will be impacted. The grid-connected inverter will output active power and reactive power, the voltage of the point common coupling becomes high, even more than the allowed range of values. The IGBT in the inverter will inevitably cause harmonic problems, the load well be affected by current harmonic. We can change the inverter control strategy to reduce the impact on the power quality and this research has been the research hotspot in this field in recent years.This thesis analysed the structure of the inverter, such as the three-phase bridge circuit, filter, current loop and power control. Inverter interfaced distributed generation model is built in simulation software.For the grid-connected inverter interfaced distributed generation will cause voltage change, used the instantaneous power theory, analysed the shortage of traditional linear of reactive power control, modified and optimized the control strategy. Used the control strategy based on variable inductance and the control strategy which combining the fuzzy control. The former requires investment in equipment and easy to cause the over voltage. The latter only need to change the control strategy and contain adaptability, can effectively regulate the point of common coupling voltage, the simulation result verified the effectiveness of the strategy.For the grid-connected inverter interfaced distributed generation will cause current harmonic, optimized the current loop PI parameters first, discuss grid voltage unbalance conditions, got the advantage and disadvantage between general control and positive and negative sequence current loop independent control, analysed the control strategy choices of under different voltage unbalance degree, to achieve the purpose of reduce current harmonic The simulation results show that the control strategy in this thesis can effectively reduce current harmonic.