The Research Of Direct-drive Permanent Magnet Wind Power System Low Voltage Ride Through Technology

In recent years the wind power industry developed rapidly，with the increasing share ofthe wind power in the power system, the research of the Wind Generator grid characteristicshas become particularly important. Direct-drive permanent magnet synchronous generator(D-PMSG) have grabbed an increasing share of the market in recent years because of its ownadvantages such as simple structure，lower cost and so on. The low voltage ride through(LVRT) issues of D-PMSG is studied in this paper, and the main content listed as following:First of all, Studied the D-PMSG’s mathematical model which includes wind turbinemodel, PMSG model, motor-side converter model, grid-side converter model, According tospace vector pulse width modulation (SVPWM) working principle，design of the motor-sidecontrol strategy and the grid-side control strategy. Furthermore, the LVRT control strategy ispresented from the energy transfer point of view.Secondly, carries out D-PMSG’s model of the simulation system in Matlab. Simulationanalysis of the wind turbine, motor-side converter, grid-side converter and D-PMSG’s LVRTare carried. The results of simulation are showed that the LVRT control strategy is right.Thirdly, based on the simulation results，the design of hardware as well as software of the150kw D-PMSG’s converter are finished. The main circuit including converter control circuitand power circuit, the motor-side converter and grid-side converter control diagram, areintroduced in this paper.Finally, through the motor-side converter and grid-side converter small powerexperiments, testify its control strategy and SVPWM algorithm, proves the converter is thecorrectness of the control principle. On the basis of the low power experiments, Rationality ofthe hardware and software design of the converter is further verified by make full powerexperiments. According to the research result, the converter control strategy proposed in thispaper is correct, The stability of the bus voltage is maintained effectively by using unloadingresistance, and the design goal is reached.