Bidirectional Power Flow Control Integrated With Pulse and Sinusoidal-Ripple-Current Charging Strategies for Three-Phase Grid-Tied Converters

ABSTRACT:

The objective of this paper is to propose bidirectional charging/discharging strategies for three-phase grid-tied converters. The bidirectional power flow control feature of the converter is able to realize both charging and discharging capability. Besides, in order to achieve high charging efficiency as well as extend the life of the battery, five charging strategies are adopted and developed: 1) the constant current (CC) charging, 2) the pulse-ripple-current (PRC) charging, 3) the sinusoidal-ripple-current (SRC) charging, 4) the bidirectional pulse-ripple-current (BPRC) charging and 5) the bidirectional sinusoidal ripple- current (BSRC) charging. The direct quadrature (d-q) transformation is utilized for the converter to realize different charging methods. These methods can be achieved by the digital signal processor (DSP) without adding extra circuit components. In addition, the charging power differences between each strategy are considered and analyzed in this paper. Finally, both simulation and experimental results obtained from a 5-kW prototype circuit verify the performance and feasibility of the proposed bidirectional charger.

KEYWORDS:

1.      Three-phase grid-tied converter

2.      Bidirectional chargers

3.      Energy storage system

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

Figure 1. The Circuit Diagram And Control Blocks.

 EXPECTED SIMULATION RESULTS:

Figure 2. Simulation Waveforms Of The V_bat , I^bat , I_d;C_md , I_ac And V_ac With Different Charging Strategies (A) The CC Charging (B) The PRC Charging (C) The SRC Charging (D) The BPRC Charging (E) The BSRC Charging.

CONCLUSION:

This paper proposes a bidirectional three-phase grid-tied converter with charging/discharging strategies. The converter is able to be operated in the AC-DC (PFC) mode and the DC-AC (inverter) mode to realize the bidirectional power flow control feature. In order to increase the charging efficiency as well as extend the battery life, five charging strategies are considered and developed. Main contributions of this paper can be concluded as: 1) a three-phase AC-DC converter with bidirectional power flow control is developed, 2) five charging/ discharging strategies are integrated with the proposed charger, 3) detailed control concepts and operational principles are revealed with mathematical derivations and 4) the charging power analysis of different charging strategies is presented. These charging methods can be achieved by the proposed bidirectional converter with the d-q transformation concept. Moreover, comprehensive analysis and mathematical derivations of the charging power differences between each strategy are presented. Finally, both simulation and experimental results obtained from a 5-kW prototype demonstrate the performance and feasibility of the proposed bidirectional charger.

REFERENCES:

[1] K. Thirugnanam, S. K. Kerk, C. Yuen, N. Liu, and M. Zhang, ``Energy management for renewable microgrid in reducing diesel generators usage with multiple types of battery,'' IEEE Trans. Ind. Electron., vol. 65, no. 8, pp. 6772_6786, Aug. 2018.

[2] P. B. L. Neto, O. R. Saavedra, and L. A. de Souza Ribeiro, ``A dual-battery storage bank con_guration for isolated microgrids based on renewable sources,'' IEEE Trans. Sustain. Energy, vol. 9, no. 4, pp. 1618_1626, Oct. 2018.

[3] U. Manandhar, N. R. Tummuru, S. K. Kollimalla, A. Ukil, G. H. Beng, and K. Chaudhari, ``Validation of faster joint control strategy for battery- and supercapacitor-based energy storage system,'' IEEE Trans. Ind. Electron., vol. 65, no. 4, pp. 3286_3295, Apr. 2018.

[4] F. Wu, X. Li, F. Feng, and H. B. Gooi, ``Multi-topology-mode gridconnected inverter to improve comprehensive performance of renewable energy source generation system,'' IEEE Trans. Power Electron., vol. 32, no. 5, pp. 3623_3633, May 2017.

[5] Z. Zhang, Y.-Y. Cai, Y. Zhang, D.-J. Gu, and Y.-F. Liu, ``A distributed architecture based on microbank modules with self-recon_guration control to improve the energy ef_ciency in the battery energy storage system,'' IEEE Trans. Power Electron., vol. 31, no. 1, pp. 304_317, Jan. 2016.