Research On Energy Optimization Control Of Micro-grid System With PV And Battery Storage

The intermittent and random nature of photovoltaic power generation system makes it difficult to realize the large-scale grid-connected application of photovoltaic power generation technology.The micro-grid makes it possible to supplement photovoltaic power generation as a traditional large-scale power grid.The flexibility of size and mode of operation of micro-grid is suitable for the representative of the distributed solar power.The energy storage system in the micro-grid can smooth the fluctuation of the photovoltaic power generation,improve the stability of the system and the power quality,but the number of the different characteristics of the powers in the micro-grid system also increases correspondingly.How to coordinate the power output between the power supply is critical for the stability and efficient operation of the system.In this paper,we take photovoltaic cells,lithium-ion batteries and super capacitor as research objects.The optimal output mode is studied based on the analysis of the characteristics of each power supply,and the energy flow in the system is optimized to prolong the service life of the equipment.Photovoltaic panels as the only power generation unit should maximize the consumption of its power generation to avoid the waste of energy.The internal power distribution of the hybrid energy storage system should be consistent with the output characteristics of lithium-ion batteries and super capacitors to extend its service life to the greatest extent.In view of the above requirements,the main work of this paper is as follows:1,Analyze the energy flow relationship between PV panels,load and energy storage units in the micro-grid.According to the existing energy storage methods and advantages and disadvantages to determine the hybrid energy storage combination method considering of the characteristics and cost of energy storage mediums.2,To find out the minimum capacity configuration of the lithium ion battery and the super capacitor at different cutoff frequencies based on the spectral analysis of the energy storage unit in the optical micro-grid system.3,To study its power characteristics through establishing the mathematical model of photovoltaic panels and determine the operation mode of the maximum power point.At the same time,the lithium-ion battery and the super-capacitor mathematical model are built to study the charge-discharge characteristics.4,The optimal operating environment and parameter range are found out through researching the influences of different parameters and operation modes of Li-ion battery and super-capacitor on its performance and life span to constraint of the internal power allocation of hybrid energy storage are determined.5,Using the fuzzy control to adjust the low-pass filter time parameters according to the operating state of lithium-ion batteries and super capacitors to optimize the internal power allocation of the hybrid energy storage.