In this paper, a grid-connected hybrid system consisting of photovoltaic (PV) array, wind turbine, and battery storage are considered and a control strategy for power flow management of the considered hybrid system with an efficient transformer-coupled bidirectional dc-dc converter is presented. This transformer is used to interface the non-conventional energy sources to the main dc bus of the system. The specified converter consists of a buck-boost converter fused with multi-input dc-dc converter and a full bridge dc–ac inverter. A boost half-bridge converter is used to tackle power from the wind generator and a bipolar buck-boost converter is used to tackle power from PV panel along with battery charging and discharging control. Compared with the traditional methods, the proposed method can coordinate all the sources in such a way that to utilize it in an efficient way using Maximum power point tracking (MPPT) control and State of charge (SOC) control for PV, Wind and battery respectively and a coordinated control strategy for MPPT and battery SOC control by reducing control complexity, also provide galvanic isolation using High frequency transformer thus significant savings in component count and also switching and conduction losses will be reduced. The presented system aims to meet the load demand, manage the power flow from considered sources, inject surplus power into the grid and charge the battery from the grid as and when required. Simulation results obtained using MATLAB/Simulink

Bidirectional buck-boost DC-DC converter, full-bridge boost DC-AC Inverter, hybrid system, maximum power point tracking, solar photovoltaic (PV), transformer coupled boost dual-half-bridge bidirectional DC-DC converter

[1] W. Kellogg, M. Nehrir, G. Venkataramanan, and V. Gerez,“Generation unit sizing and cost analysis for stand-alone wind, photovoltaic and hybrid wind/PV systems,”IEEE Trans. Ind. Electron., vol. 13, no. 1, pp. 70-75, Mar. 1998.
[2] B. S. Borowy and Z. M. Salameh,“Dynamic response of a stand-alone wind energy conversion system with battery energy storage to a wind gust,” IEEE Trans. Energy Convers., vol. 12, no. 1, pp. 73-78, Mar. 1997.
[3] F. Valenciaga, P. F. Puleston, and P. E. Battaiotto, “Power control of a solar/wind generation system without wind measurement: a passivity/sliding mode approach,” IEEE Trans. Energy Convers., vol. 18, no. 4, pp. 501-507, Dec. 2003.
[4] Z. Qian, O. A. Rahman, and I. Batarseh, “An integrated four-Port DC/DC converter for renewable energy applications, "IEEE Trans. Power Electron.,vol. 25, no. 7, pp. 1877-1887, July. 2010.
[5] F. Nejabatkhah, S. Danyali, S. Hosseini, M. Sabahi, and S. Niapour, “Modeling and control of a new three-input DC-DC boost converter for hybrid PV/FC/battery power system,” IEEE Trans. Power Electron., vol. 27, no. 5, pp. 2309-2324, Feb. 2014.
[6] H. C. Chiang, T. T. Ma, Y. H. Cheng, J. M. Chang, and W. N Chang, “Design and implementation of a hybrid regenerative power system combining grid-tie and uninterruptible power supply functions,” IET Renew. Power Gen., vol. 4, no. 1, pp. 8599, 2010.
[7] F. Giraud and Z. M. Salameh, “Steady-state performance of a grid-connected rooftop hybrid wind-photovoltaic power system with battery storage, ” IEEE Trans. Energy Convers., vol. 16, no. 1, pp. 1-7, Mar. 2001.
[8] S. K. Kim, J. H. Jeon, C. H. Cho, J. B. Ahn, and S. H. Kwon, “Dynamic modeling and control of a grid-connected hybrid generation system with versatile power transfer," IEEE Trans. Ind. Electron., vol. 55, no. 4, pp. 1677-1688, Apr. 2008.
[9] H. Wu, K. Sun, S. Ding, and Y. Xing, “Topology derivation of non-isolated three-port dc-dc converters from DIC and DOC,” IEEE Trans. Power Electron., vol. 28, no. 7, pp. 3297-3307, July 2013.
[10] W.Li, C. Xu, H. Luo, Y. Hu, X. He, and C. Xia, “Decoupling-Controlled Triport Composited DC/DC Converter for Multiple Energy Interface” IEEE Trans. Ind. Electron., vol. 62, no. 7, pp. 4504-4513, July 2015.
[11] C. Xu, Y. Gu, H. Luo, Y. Hu, Y. Zhao, W. Li and X. He, “Performance analysis of coupled inductor based multiple-input DC/DC converter with PWM plus phase-shift (PPS)control strategy,” in Proc. of IEEE Energy Conversion Congress and Exposition, ECCE Asia’2013, pp. 994-998, Sept. 2013.
[12] B. Mangu and B.G. Fernandes, “Multi-input transformer coupled DCDC converter for PV-wind based stand-alone single phase power generating system, ” in Proc. of IEE EEnergy Convers. Congr. Expo. (ECCE), Pittsburgh, PA, USA, Sep. 2014, pp. 5288–5295.
[13] B. Mangu, S. Akshatha, D. Suryanarayana, and B. G. Fernandes, “Grid-Connected PV-Wind Battery based multi-input transformer-coupled bidirectional DC-DC converter for household applications,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 4, NO. 3, pp. 1086-1095, September 2016