Control Strategy For Direct-drive Wind Power Converters With PMSG Based On Direct Power Control

More and more attention has been drawn in renewable energy, and wind energyhas drawn greater attention in recent years.As an important part of the clean energy,wind energy is inexhaustible and pollution-free.Meanwhile, because of shortconstruction period and quick benefit and low cost of maintenance, the wind farm isthe first choise of the replacement of unrenewable energy.Permanent magnet directdrive wind power system is especial of gearless, low maintenance and low noise, itattracts more and more attention., and it has became an important direction for futuredevelopment of the wind power system.In this paper, theme is the operation andcontrol of the permanent magnet direct drive wind power converter, a detailedtheoretical analysis and mathematical modeling of direct drive wind power systemand direct power control strategy of the grid side and machine side is proposed.First, development status of wind energy and wind power generation technologyresearch are introduced.Starting from the calculation of wind energy, thecharacterristics of the wind turbine are reserched, meanwhile, modeled andsimulated.as the components of the wind power system for the converter,mathematical models of the PMSM, PWM converter and DC bus link are detiallyintroduced.It makes a base for the future analysis.Secondly, introduced the theoretical analysis and mathematical modeling ofdirect power control Strategy of the grid side converter and compared with thetraditional grid voltage oriented vector control. Direct power control of the gridvoltage-oriented control method is based on the idea of the instantaneous powertheory is a new type of converter control method, the control method of rounding thecurrent loop of grid voltage oriented, use the power directly as the inner loop, and theactive power and reactive power can be estimated directly using the DC voltage andthe switch value, eliminating the need for grid voltage sensors, no current loop canreduce the number of coordinate transformation, and enhance the stability of thesystem. Direct power control system, in order to achieve unity power factorconditions required reactive power is zero, active power instruction is given by theoutput of DC voltage loop controller. The direct power control stragety theoreticalanalysis and mathematical modeling of the machine side converter is introduced andis compared with the traditional permanent magnet synchronous rotor flux-oriented vector control technology, the directional control of the rotor flux and electromagneticswitch to the coordinate transformation on the basis of moment equations, bycontrolling the dq axis current,to reach torque and magnetic control, direct powercontrol directly from the power to give the inverter switch, simplifying the theconventional rotor flux oriented vector control algorithm and improved the stability ofthe system.Finally, demonstrated the effectiveness of the proposed direct power controlalgorithm by simulation and experimental results.