Research On Inverter And Control System Of Off-grid Wind Power Generator

As a clean and renewable green energy,wind energy has been highly valued in the world,and has been widely developed and utilized.In addition to grid-connected applications,the off-grid application of wind energy is also widespread,especially in remote areas such as islands.The research group develops a supporting power generation control system for a company’s patented technology of micro-wind magnetic levitation wind generator.The research group focuses on the control strategy research of the inverter,and the topic and work have important theoretical significance and practical value.This paper focuses on the decoupling and control strategy of the three-phase four-leg inverter.Through the mathematical modeling of the topology of the three-phase inverter,combining the theory and the formula to deduce its model.It is proved that the fourth leg can be separated from the coupling of the former three legs,and the relationship between variables such as output voltage and current between legs is obtained.Through the Matlab simulation experiment,it is important to consider that ordinary three-phase three-leg inverter cannot generate three-phase symmetrical voltage under the condition of unbalanced load.A new closed-loop control design scheme for the three-phase four-leg inverter is proposed.The former three legs of the inverter adopt space vector pulse width modulation,the fourth leg adopts neutral point current hysteresis modulation.Compared with the three-leg inverter,the four-leg inverter of this project not only enhances the system’s ability to carry unbalanced loads,but also improves the efficiency and total harmonic distortion of the inverter system.In view of the needs of the research,the hardware and software of the three-phase four-leg inverter system is designed and debugged.Under the condition of balanced load and unbalanced load,four-leg inverter output voltage and current test experiments were conducted to verify the effectiveness of the control scheme.At the same time,the selection and experiment of double power automatic transfer switch,the distribution scheme of the electric control cabinet and the redundant protection of the control panel are designed,the integrated assembly is carried out on the system electric control cabinet,and the equipment of the off-grid magnetic levitation wind power generation system is combined and finalized.In order to improve the interactivity of the control system,the e View touchscreen is used as human-computer interaction interface and real-time data communication with the programmable controller,making the whole device more user-friendly.Finally,based on the research of three-phase three-leg inverters and three-phase four-leg inverters,this paper further explores the control strategies of space-saving matrix converters that do not require energy storage elements.And designs the magnetic levitation wind power generation system matrix by using the predictive current control of instantaneous reactive power minimization.The new control scheme of converter not only improves power quality on both sides of generator and load,but also enhances load current fast tracking ability.