Engineering Application And Control Strategy Research Of Photovoltaic Generation Technology

Distributed power generation technology is one of the effective ways to use renewable energy.Under the background of increasing energy and environmental pressure,promoting the development of distributed power generation has become one of the important measures to promote energy conservation,emission reduction and climate change.Photovoltaic(PV)power generation technology is an important part of distributed power generation technology,and it is also the distributed energy form mainly promoted by the country at present.In order to support the large-scale application of PV systems,China government has promoted the orderly development of distributed power generation through the introduction of encouraging policies,scientific development plans,clear and unified grid-connection standards,establishment of a reasonable price mechanism,and support of the research and development of core technologies.As China's largest power enterprise and leader in the power industry,the state grid corporation of China is also responsible for promoting the development of global energy Internet and promoting distributed PV system.Based on the PV system,this paper conducts an in-depth study on the structure of distributed PV power generation system,key control technology,engineering design feasibility analysis of PV projects.The specific research contents are as follows:1.The research object of this paper is two-stage LCL PV inverter system.The working mode of Boost circuit is analyzed and its output voltage characteristic is modeled.The circuit of single-phase LCL inverter is modeled mathematically and the transfer function of current and DC voltage is derived.2.Based on the power characteristics of PV cells,the traditional constant voltage method,incremental conductance method and perturbation observation method,two MPPT(Maxim Power Point Tracking)algorithms that can improve the tracking speed and accuracy are proposed.One is the constant voltage & perturbation observation method,and the other is the constant voltage & incremental conductance method.3.LCL inverter control usually adopts the capacitive current feedback method to eliminate the resonance peak,but according to the transmission function analysis,the grid voltage has a great impact on the grid-connected current.Therefore,this paper studies a kind of grid voltage feed-forward control,reduces the influence of grid voltage distortion on the grid current,and improves the power quality of the grid current.Finally,taking the power generation project of Donganmin village in the southwestern suburbs of Dandong city as an example,the technical indicators of the PV system,the selection of key components and the design of control system control process are studied,and the feasibility of the engineering design is verified.