Predictive Control Of A Three Level Boost Converter And T-type Inverter In Wind Energy Conversion Systems

As the most promising technology,wind power generation has drawn great attention to many countries such as United States,Britain,France,and Denmark.At the same time,a series of policies and measures have been adopted by those countries we mentioned above.Because of these policies and measures,the development of wind power generation has been highly promoted all over the world.Under the improvement of the international wind power technology environment,the enterprises in China have been developed rapidly with the support of our government.Due to the increasing requirement of the wind power grid technology and industrial production capacity,also,the demand of control technology of the inverter in wind power system is becoming greater.The issue is mainly based on the permanent magnet direct-drive wind power grid system,researching for control strategy of the three level boost(TLB)converter with the cascade structure of T-type inverter.The main research of this paper is as follows:(1)Introduces the types and characteristics of the wind power integrated transformation system,and the selected topological structure in the wind power integrated control system of this paper.As the upgrade rate of the voltage in traditional boosted circuit can not meet the need of the current high-power and high-voltage of the wind power production,a topological structure TLB converters and T-type three-level inverters for direct-drive wind power generation systems are proposed in this paper.In this structure,because of the increasing number of the Boost-TL converter switch,the work mode is also getting more and more,which results in controlling the freedom degree when charging and discharging DC voltage grading capacitor with extra attention.Thus it will distribute the control of the grid-connected inverter with mid-point,which makes the division of the work clearly and the control-target directly.(2)Based on the topology of Boost-TL converter and improved T-type inverter,they adopt the traditional PI control of SVPWM and model estimation respectively to make the comparative analysis.Focusing on the derivation process of model estimation and verifying the advantages of model estimation with higher robustness and faster dynamicresponse,what we have mentioned above are widely used in inverter control.Owing to the unfixed switching frequency of traditional estimation control and the irregular status switching on-off,we have to keep the action of switch regular in order to improve the out-put wave.This paper adopts a simple and easy method of status switching estimation based on the space voltage vector,and it not only simplifies the redundant calculation of the model estimation control but also decreases the current harmonic factor.To make the theoretical analysis and the simulation experiment verification with he controlling technology of Boost-TL converter and improving T-type inverter integration,the results prove that the improved algorithm could improve the current tracking accuracy and make the status switching on-off better.In this way,both the distortion of the current harmonic factor and the electromagnetic noise decrease.Also this method could be used in a wider range and improve the stability of system.(3)Based on the theoretical analysis,a MATLAB simulation model based on three-level booster converter and improving T-type inverter integration and a corresponding experiment platform based on TMS320F2812 have been set up,so that he experimental results have proved that theoretical analysis and control strategy are correct and feasible.