Research On Photovoltaic-battery Microgrid Experimental System

With more and more new energy generation connected to the public grid,intermittently and volatility of its output power has brought new challenges to the grid,such as security and stability operation,regulation of peak and frequency.Microgrid containing a large number of renewable energy will be in a high proportion of power distribution network,that is,high permeability,which will change the distribution network power flow distribution and the nature of the network.In this paper,we design a microgrid experiment system with PV-battery,and develop a corresponding microgrid operation control strategy to verify the feasibility of PV-battery system to participate in secondary AF.The main work of the full text is as follows:Firstly,I designed and manufactured two sets of inverters for connecting to public grid and a set of bidirectional DC converter which can be used for battery charge and discharge management.When the inverter is connected to the grid,the inverter uses the public grid voltage/frequency as the reference to adopt the constant power control.When the inverter operates independently,the V/f control is used to provide the voltage/frequency support for the system.The experimental results show that the inverters and converters work stably,with high efficiency and less harmonic content.Secondly,for the further research of the microgrid characteristics and operation mode,the topologies of PV-battery microgrids system were designed based on two sets of inverters and a set of bi-directional converters fabricated in the previous period.Set up a small micro-grid experimental system in the laboratory.The system uses dSPACE1103 as the upper control center,which can achieve mutual coordination between inverters and converters.Thanks to grid-connected inverter instantaneous power response capability,the strategy is proposed to participate in auxiliary second frequency regulation of the power grid by using the multifunctional PV-battery system.when the grid frequency is abnormal,multiple operation modes of the PV-battery generation system participating in the auxiliary second frequency regulation were analyzed and a hierarchical coordinated control strategy was presented considering the rated capacity of grid-connected inverter,solar radiation conditions,battery charge and discharge status,and etc.Thirdly,based on the experience gained from the construction of laboratory microgrid platform,we participated in the Tianjin science and technology support plan "Wind and solar intelligent microgrid for the electric vehicle wireless charging"demonstration project.Mainly responsible for the design of pre-construction demonstration project planning,electrical topology design,monitoring system design,system capacity selection and configuration of the final installation and commissioning work.