Photovoltaic Power Friendly Grid-connected Interface And Research On Hybrid Control Of Grid-connection

The trend of present world economic development is low carbon economy.Developing and using the renewable, environment friendly new energy is an effectiveway to solve the problem of traditional energy shortage and environmental pollution. Itis an inevitable trend that large-scale developing and using solar energy for solarphotovoltaic power generation as an idea power generation forms of green energy. Butthe randomness and uncertainties of solar photovoltaic power generation which isaffected by sunlight intensity and temperature lead to the problem of power qualitywhich control unstable output power, harmonic pollution from the grid process,unstable voltage and so on. It is seriously restricting the development of thetechnology of solar photovoltaic power generation. Study on the structure and controlmethod of the photovoltaic grid-connected power interface which as the key equipmentof energy conversion and control in the photovoltaic power generation system andmaking it friendly complement with the main power grid has important theoreticalsignificance and practical value.At the first, the concept and characteristics of the hybrid system, and severalmodeling approach of the hybrid control theory are elaborated, and the design methodof the hybrid control system are analyzed, and then the achievements of the hybridcontrol theory in the practical application is introduced. Then, the hybridcharacteristics of grid-connected PV generation system are analyzed from the fouraspects which respectively contain photovoltaic power, grid-connected interface, themode of system operation and the main power grid and the model of grid-connected PVcontrol based on the hybrid automata theory is established. Next, the topologicalMPPT hybrid control method is proposed, and structure of photovoltaic friendlygrid-connected power interface is researched, and the two models which containgrid-connection and island operation of photovoltaic power are analyzed, and usinghybrid control method to realize multiple functions of active transport, reactive powercompensation, harmonic suppression, three-phase equilibrium and so on, and thefriendly grid-connected hybrid controller is designed, and using Matlab/Simulink software to simulation experiment is carried out. Finally, the control system of friendlygrid-connected power interface based on the technology of DSP is designed.The theory analysis and the results show, using hybrid control method to controlthe photovoltaic power grid-connected interface in this paper can choose the optimaloperation mode accord to the change of external environment, and realize multiplefunctions of active transport, reactive power compensation, harmonic suppression andthree-phase equilibrium which can greatly improve the quality of the grid power andthe stability of the system and achieve the aim of cgrid-connection.