Design And Simulation Research Of Modular Permanent Magnet DC Turbine Based On MIT

Offshore wind resource could be huge and stable.Its reasonable utilization such as offshore wind farms could reduce the occupation of land resources,have small noise disturbance impacts,and gradually become a new trend in the development of wind power.Solution of all-DC wind farms with both DC energy collection and transmission is of great significance to the power supply in coastal areas.However,because of many technical barriers that have not been broken through,only few of all-DC wind farms have been built in the world.Traditional topologies of all-DC offshore wind farms raised terminal voltage by connecting multiple generators in series,which would cause problems of additional insulation enforcement for generator windings,complex power distribution and voltage stable control under circumstances of wind speed variation and potential faults.The modular idea of permanent magnet DC turbine was proposed in this paper,which includes modular permanent magnet synchronous generator(PMSG),AC/DC converters in generator side,DC/DC converters in grid side,and magnetic integrated transformer(MIT)as well.The PMSG consisted of multi-module fractional slot concentrated winding and direct-driven rotor,namely FSCW DDPMSG.The component of MIT directly produced high voltage direct current(HVDC)at the output terminal of the grid,which was of strong fault tolerance.Design criteria of FSCW DDPMSG were taken into considerations in this paper.Optimal codes were designed in MATLAB environment as an example of 8 sets three-phase windings with capacity of 5 megawatts.The finite element analysis was carried out based on ANSYS MAXWELLsoftware.Moreover,the topologies of both AC/DC converters in generator-side and DC/DC converter isolated by MIT in grid-side were designed,and their working modes were detailed analyzed.Both power factor correction(PFC)of AC/DC converters and voltage stability control(VSC)of DC/AC converters in generator-side were designed.The results based on PLECS software simulation showed that controls of the modular permanent magnet DC turbine based on MIT can achieve smooth transitions during starting,variable wind speed,fault operations and stop process,and realize the maximum power point tracking(MPPT),which verified the rationality and feasibility of the proposed modular topology and control strategies.This work could provide useful technical reference for designing of the future all-DC offshore wind farms.