Research On Power Control Strategy For Photovoltaic Generation System Based On Virtual Synchonous Generator

Technology of solar photovoltaic(PV) grid-connected power generation is currentlyone of the hot new energy research and development,and has promoted its rapiddevelopment and wide range of application. However,there is a big difference betweenphotovoltaic power generation system and the traditional form of generation, thenegative impact of its large-scale applications deserves concerning, and graduallyattracted people’s attention. Synchronous generator has better networking features,making PV generation systems to simulate characteristics of synchronous generator willeffectively avoid risks of large-scale application of photovoltaic existing, hassignificante meaning for the development of photovoltaic technology.Firstly, works and structures of the PV power generation system are analyzed, mat-hematical models of PV inverters with L and LC filters were deduced and thecorresponding control strategies are analysized, application status of energy storage inPV generation systems were introduced, which laying basis for researching onimplenmentation control technology of virtual synchronous generator in PV powergeneration systems which combine energy storage.The virtual synchronous generator(VSG) algorithm is estabilished based onsecond-order model of synchronous generator, it carries out a detailed analysis of itsbasic characteristics and virtual inertia. Impact of controller parameters closed-loopcontrol of reactive power on system characteristics when using, in order to achieveflexible control is proposed based on the coordinate transformation to achieve activeand reactive power decoupled reactive power control method that can achieve accuratereactive power output, and avoid mutual influence of active and reactive power. Forinverter with current control methods photovoltaic systems, proposes a method toachieve VSG power control algorithm, which aim at reaching simulate synchronousgenerator characteristics of the premise, to avoid increasing system complexity andreduce the problem of control reliability.Based on the research of VSG algorithms, it promote VSG control technology tothe operation control of microgrid, propose a microgrid control strategy that based onVSG control technology, with the difference in control, distributed PV generations areclassified into networking and grid-connected unit, on the premise of their ability ofrunning in dual-mode and autonomous load sharing in microgrid, flexible control of distributed PV generations is realized. It analysis frequency and voltage regulation inislanding operation mode of microgrid, it propose a control strategy ofpre-synchronization base on virtual power，microgrid can transfer from islanding modeto grid-connected mode smoothly without detection frequency or phase.Finally, the simulation model of the system is established in MATLAB/Simulink,the simulation results show that：(1)With the application of VSG algorithm，virtualinertia is implemented PV generation system, reactive power control based on thecoordinate transformation decoupling achieve a good effect, and can avoid the impacton the system dynamic characteristics；(2)The method which implemente VSGalgorithm through the power control can achieve virtual inertia, and the system has agood reliability；(3)The operation control strategy of microgrid based on the VSGrealized a reliable operation, pre-synchronization control strategy of microgrid based onvirtual power can realize an accurate synchronization of voltage between microgrid andthe main grid.