The Design of a New Double Loop Controller For Simultaneous Adjustment of Input and Output Voltages of Single-Phase Grid-Connected Inverter



Although LCL filters are used widely in the grid connected inverters to reduce high-order
harmonics, such a system increases system order and therefore sustainable design of closed-loop
controller system will be complicated. Recently, the single-loop control strategy has been
suggested for L or LC filter based grid-connected inverters. However, the use of single-loop
control directly in LCL filter-based inverters may cause instability. In this paper, a new doubleloop
control strategy is presented which includes a voltage external loop and an internal loop of
filter capacitor current. The external loop controls the input voltage of the grid-connected
inverter. The internal loop improves system stability margin and removes the resonance of LCL
filter. To obtain the transfer function of system, single-phase instantaneous power theory is used.
The computer simulation has proved the feasibility of the proposed control


[1] J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galvan, R.C. P. Guisado, M. A. M. Prats, J. I. Leon, and N. Moreno-Alfonso, (2006). “Power electronic for the grid integration of renewable energy sources: a survey,” IEEE Transactions on Industrial Electronics, Vol. 53, No. 4, pp. 1002- 1006.
[2] A. A. Ferreira, J. A. Pomilio, G. Spiazzi, and L. de Araujo Silva, (2008). “Energy management fuzzy logic supervisory for electric vehicle power supplies system,” IEEE Transactions on Power Electronics, Vol. 23, No. 1, pp. 107-115.
[3] E. Twining and D. G. Holmes, (2003). “Grid current regulation of a three-phase voltage source inverter with an LCL input filter,” IEEE Trans. Power Electron., Vol. 18, No. 3, pp. 888-895.
[4] P. C. Loh and D. G. Holmes, (2005). “Analysis of multiloop control strategies for LC/CL/LCL-filtered voltage-source and current-source inverters,” IEEE Trans. Ind. Electron., Vol. 41, No. 2, pp. 644-654, Mar.
[5] J. Dannehl, F. W. Fuchs, and P. B. Thøgersen, (2010). “PI state space current control of grid-connected PWM converters with LCL filters,” IEEE Trans. Power Electron., Vol. 25, No. 9, pp. 2320-2330.
[6] Liserre M., Blaabjerg F., Hansen S., (2005). “Design and Control of an LCL-Filter-Based Three-Phase Active Rectifier,” IEEE Trans. Ind. Appl., vol. 41, no. 5, pp. 1281-1291.
[7] Aslain Ovono Zue and Ambrish Chandra, (2006). “Simulation and Stability Analysis of a 100kW Grid Connected LCL Photovoltaic Inverter for Industry,” Power Engineering scociety general meeting 2006, pp.2239-2244.
[8] M. Liserre, A. Dell’Aquila, and F. Blaabjerg, (2004). “Genetic algorithm-based design of the active damping for an LCL-filter three-phase active rectifier,” IEEE Trans. Power Electronics, vol. 19, no. 1, pp. 76-86.
[9] M. Liserre, R. Teodorescu, and F. Blaabjerg, (2006). “Stability of Photovoltaic and Wind Turbine Grid-Connected Inverters for a Large Set of Grid Impedance Values,” IEEE Transactions on Power Electronics, vol. 21, no.1, pp. 263- 272.
[10] M. Liserre, A. Dell’Aquila, and F. Blaabjerg, (2002). “Stability improvement of an LCL-filter based three-phase active rectifier,” PESC’02, vol. 3, pp. 1195-1201.
[11] Leonardo Augusto Serpa, Srinivas Ponnaluri, Peter Mantovanelli Barbosa and Johann Walter Kolar, (2007). “A Modified Direct Power Control Strategy Allowing the Connection of Three-Phase Inverters to the Grid Through LCL Filters,” IEEE Trans. Ind. Appl., vol.43, no. 5, pp. 1388-1400.
[12] Guoqiao Shen, Dehong Xu, Danji Xi, Xiaoming Yuan, (2006). “An Improved Control Strategy for Grid-connected Voltage Source Inverters with a LCL Filter,” APEC’06, pp. 1067-1073.
[13] Remus Teodorescu, Frede Blaabjerg, Marco Liserre and Antonio Dell’Aquila, (2003). “A stable three-phase LCL-filter based active rectifier without damping,” IAS’03, vol. 3, pp. 1552-1557.
[14] E. Twining and D.G. Holmes, (2003). “Grid Current Regulation of a Three-Phase Voltage Source Inverter with an LCL Input Filter,” IEEE Trans. Power Electronics, vol. 18, no. 3, pp. 888-895.
[15] L. Mihalache, (2005). “A high performance DSP controller for three-phase PWM rectifiers with ultra low input current THD under unbalanced and distorted input voltage,” IAS’05, vol. 1, pp. 138-144.
[16] A. Papavasiliou, S.A. Papathanassiou, S.N. Manias and G. Demetriadis, (2007). “Current Control of a Voltage Source Inverter Connected to the Grid via LCL Filter,” PESC’07, pp. 2379-2384.
[17] F.A. Magueed and J. Svensson, (2005). “Control of VSC connected to the grid through LCL-filter to achieve balanced currents,” IAS’05, vol. 1, pp. 572-578.
[18] E. Wu and P.W. Lehn, (2006). “Digital current control of a voltage source converter with active damping of LCL resonance,” IEEE Trans. Power Electronics, vol. 21, no. 5, pp. 1364- 1373.
[19] Fei Liu, Shanxu Duan, Pengwei Xu, Guoqiang Chen and Fangrui Liu, (2007). “Design and Control of Three-Phase PV Grid Connected
Converter with LCL Filter,” IECON’07, pp. 1656-1661.
[20] C. Y. Hsu and H. Y. Wu, (1996). “A new single-phase active power filter with reduced energy-storage capacity,” Proc. Inst. Elect. Eng.—Elect. Power Appl., vol. 143, no. 1, pp. 25–30.
[21] K. Mahabir, G. Verghese, J. Thottuvelil, and A. Heyman, (1990). “Linear averaged and sampled data models for large signal control of high power factor AC–DC converters,” in Proc. IEEE PESC, pp. 372–381.
[22] R. Ridley, (1989). “Average small-signal analysis of the boost power factor correction circuit,” in Proc. Virginia Power Electron. Center Semin., Blacksburg, VA, pp. 108–120.