Research On Control Strategy And Realization Of Voltage Sag Generator

Voltage dip generator (VSG) is a device for grid fault simulation. It is mainlyused to test wind power system and solar photovoltaic system grid fault ride-throughcapability and test the performance of various compensation device. Themathematical model and control strategy of VSG, and the development of theexperiment system of VSG and so on are all researched in this paper. Firstly, thetransient mathematical model of VSG under abc three-phase static coordinate systemand under dq synchronous rotating coordinate system are built in this paper. Secondly,the control strategy of VSG is studied in-depth. Network side used double-loopdecoupling control algorithms. Side of the fault proposes a simple method ofgenerating power grid fault simulation based on a voltage vector relationship of faultgenerating. In order to maintain the DC bus voltage stability, adding a powerfeedforward control strategy. Afterwards, Relying on the construction of State KeyLaboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University), design the experiment system of VSG,including the design of main circuit, control system, monitoring subsystem and otherhardware circuit of experiment system. And then, in order to solve the traditionalDSP control system development cycle is long, difficult issues, combined with RTW(Real Time Workshop) technology, provides an overview of a fast and efficient DSPcontrol system development methodology. And this method is applied to thedevelopment of DSP control program of experiment system. Finally, the principle ofthe experimental system hardware circuit was debugged, and the effectiveness of thecontrol strategy was validated. Experimental results show that the studied VSGsystem can simulate the sudden increase in grid voltage symmetrical fault, a varietyof symmetric and asymmetric voltage dip fault and failure frequency fluctuations.Grid fault type, depth and time can be set accurately.While the phase voltage isautomatically satisfied the phase relationship between the phases and the amplitudeof phase relationship between the phases.