Direct Drive Wind Power System Converter Control Strategy

As a kind of Pollution-free and green renewable energy, wind Power has a verypromising future, many countries attach great importance to the development and useof wind energy, as wind Power industry develops rapidly, direct-driven wind Powersystem attracted wide attention for many advantages, it is now one of the currentresearch focus, while the full-scale power converter control technology is the coretechnology of direct-driven wind power generation system. The converter itsperformance affects the performance of the system directly. Most direct-driven windpower generator system adopts dual-PWM converter topology structure, because thistopology structure has merits of the controlled power factor, sinusoidal current of ACside and two direction transmission of energy.In view of the nonlinearity of dual-PWM converter mathematical models indirect-drive wind power system, in order to improve the control precision of thecontroller, Passivity based on hybrid control strategies were proposed for machineside converter, which contains passivity based on control and the outer voltagesquared PI, passivity based on control and PI, passivity based on control and ADRC;while the grid side converter, passivity based on hybrid control strategy was proposed,and the mathematical models were established and the controller were designed, Inorder to improve the dynamic performance of the converter, we can adopt theapproach called injecting damping to optimize the controllers, The final designedcontrollers have many advantages, such as simple algorithm, less adjustableparameters and good dynamic performance,etc. Simulation is conducted by MATLABsoftware; Based on TMS320F28335DSP, an experimental platform is developed toverify the validity of the proposed control system. Through the Prototype experiments,the inverter can achieve the grid ac current sinusoidal, the unity power factor, and hasan excellent grid-connected characteristic. And indicate that a hybrid control based onpassivity is practical.A novel hybrid control strategy based on passivity and PI control is adopted inthis paper for Low voltage ride through in direct-drive wind power system.In orderto enhance low voltage ride through (LVRT) capability and stabilize output power ofdirect-drive permanent magnet wind power system, this paper presents using thegrid-side voltage drop signal feedback to the rectifier side as the output power reference value, and decrease the dc side power imbalance, The simulation resultsshow that the machine side converter output power is reduced, the DC voltage canfast-track expectations; the grid side converter can achieve unity power factor whenthe grid voltage drop, achieve low voltage ride through and has a certain theoreticaland practical significance.