Energy Management Studies For Battery Storage System Of Building Integrated Photovoltaic(BIPV)

Reducing CO₂ emissions is a necessary subject due to the existing ecological problems.Many alternative energy sources can be used instead of fossil fuels.It is widely believed that solar energy can sustainably replace fossil fuel sources without harming the environment.Commercial and residential photovoltaic（PV）systems are extensively coming into the market due to the following advantages:（1）More affordable costs with respect to homeowners’ economic situations and（2）Utilizing the roof of the buildings as the supporting structure,thereby eliminating land and direct structure expenses.However,proper interfaces will need to be provided between these systems and the utility in order to maximize the benefits associated with them.Because,when BIMG operating on-grid,PV generation as an intermittent energy source,is random and Building as the AC load is uncertain,which will cause exchange power fluctuating at the interconnection point and influence the low voltage power distribution.Meanwhile,the time proconsumer hope to trade back to grid is not consistent with the time the grid willing to.So,the energy storage system should be considered to apply in the BIMG can improve the power quality inject to the grid,smoothing the exchange power fluctuation and store residue product.This paper focuses on the application of battery energy storage systems（BESS）in Grid-connected BIMG based on state-space model（s）and an effective approach for peak load shaving using BESS.Firstly,the system structure and characteristics of the grid-connected Building Mounted with Photovoltaic system（BMPV）with batteries,Building Integrated Microgrids（BIMG）,were discussed as well as its micro sources,Photovoltaics and batteries.Based on which derived and built the model for BUCK/BOOST converter of the BESS.Secondly,discussed the topology and operation principle of Modular Multilevel Converter（MMC）;derived and built its three-phase state-space model.Based on its lower level control method,modified Nearest Level Control（NLC）to fit the system we proposed;Analyzed N+1 modulation and steps to fulfil 2N+1 Modulation for the particular model we proposed.Then,control methods of the system were discussed: the MMC employs Voltage Oriented Control（VOC）for the upper level control to achieve power decoupling and the stability of DC voltage.After which,the state-space model for proposed BIMG was derived and built.This paper also proposed a control strategy based on state-space model（s）of BIMG by utilizing an energy management strategy and BESS charging/discharging control strategy with the goal of peak-shaving,while considering batteries’ degradation and ageing limits.Next,BIMG state-space model simulation platform was build using Simulink/SimPowerSystems toolbox under Matlab based on the state space models of MMC and BESS.Simulations have been performed both in sufficient and insufficient battery capacity cases and the results were analyzed,which verified that the proposed energy management strategy can achieve good performance of the BIMG.