New control strategy for three phase grid-connected lcl inverters without a phase-locked loop
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The document presents a new control strategy for three-phase grid-connected LCL inverters that eliminates the need for a phase-locked loop (PLL). By utilizing an instantaneous power control scheme and a positive-sequence voltage detector, the strategy effectively generates current references, demonstrating improved performance under various grid conditions. Simulation and experimental results validate the effectiveness of the proposed control structure, highlighting its advantages in steady-state and transient behaviors.
![ELECTRICAL PROJECTS USING MATLAB/SIMULINK
Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in
0-9347143789/9949240245
For Simulation Results of the project Contact Us
Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in
0-9347143789/9949240245
CONCLUSION:
A new control structure for three-phase grid-connected voltage source inverters (VSI) with an
LCL-filter is proposed. By using the instantaneous power control scheme and the proposed
positive-sequence voltage detector, the current reference can be indirectly generated, which
avoids the complex PLL. The effectiveness of the proposed system for three-phase grid-
connected VSIs is demonstrated via simulation results, which show a significant improvement in
both the steady state and transient behavior. The same behavior is experimentally verified. The
fast dynamic response to a reference step is not affected by the inclusion of additional control
loops. Good performance is guaranteed even under unbalanced and distorted grid voltages.
REFERENCES:
[1] X. Wang, J. M. Guerrero, F. Blaabjerg, and Z. Chen, “A review of power electronics based
microgrids,” Journal of Power Electronics, Vol. 12, No. 1, pp. 181-192, Jan. 2012.
[2] S. Peng, A. Luo, Y. Chen, and Z. Lv, “Dual-loop power control for single-phase grid-
connected converters with LCL filters,” Journal of Power Electronics, Vol. 11, No. 4, pp. 456-
463, July. 2011.
[3] F. Blaabjerg, R. Teodorescu, M. Liserre, and A. V. Timbus, “Overview of control and grid
synchronization for distributed power generation systems,” IEEE Trans. Ind. Electron., Vol. 53,
No. 5, pp. 1398-1409, Oct. 2006.
[4] R. Inzunza, T. Sumiya, Y. Fujii, and E. Ikawa, “Parallel connection of grid-connected LCL
inverters for MW-scaled photovoltaic systems,” in Proc. IEEE IPEC, pp. 1988-1993, 2010.
[5] T. Noguchi, H. Tomiki, S. Kondo, and I. Takahashi, “Direct power control of PWM
converter without power-source voltage sensors,” IEEE Trans. Ind. Appl., Vol. 34, No. 3, pp.
473-479, Mar./ Jun. 1998.](https://image.slidesharecdn.com/newcontrolstrategyforthree-phasegrid-connectedlclinverterswithoutaphase-lockedloop-161219082618/85/New-control-strategy-for-three-phase-grid-connected-lcl-inverters-without-a-phase-locked-loop-6-320.jpg)
New control strategy for three phase grid-connected lcl inverters without a phase-locked loop
- 1. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 New Control Strategy for Three-Phase Grid-Connected LCL Inverters without a Phase-Locked Loop ABSTRACT: The three-phase synchronous reference frame phase-locked loop (SRF-PLL) is widely used for synchronization applications in power systems. In this paper, a new control strategy for three- phase grid-connected LCL inverters without a PLL is presented. According to the new strategy, a current reference can be generated by using the instantaneous power control scheme and the proposed positive-sequence voltage detector. Through theoretical analysis, it is indicated that a high-quality grid current can be produced by introducing the new control strategy. In addition, a kind of independent control for reactive power can be achieved under unbalanced and distorted grid conditions. Finally, the excellent performance of the proposed control strategy is validated by means of simulation and experimental results. KEYWORDS: 1. Control strategy 2. Grid-connected inverters 3. Instantaneous power control scheme 4. LCL filter 5. Positive-sequence voltage detector SOFTWARE:MATLAB/SIMULINK
- 2. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 BLOCK DIAGRAM: Fig. 1. Block diagram of the control systemwith LCL filter.
- 3. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 EXPECTED SIMULATION RESULTS: Fig. 2. Simulation results of the proposed control system. (a) Generated current reference signals. (b) A-phase grid voltage and three-phase current. (c) Actual active and reactive powers.
- 4. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 Fig. 3. Experimental results of the positive-sequence voltage detector under actual grid operating conditions. (a) Utility voltage and the detected positive-sequence signals. (b) Harmonic spectrum of the utility voltage. (c) Harmonic spectrumof the detected positive-sequence signals.
- 5. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 Fig. 4. Experimental results of a step in the reactive power reference. (a) A-phase grid voltage and three-phase current. (b) A-phase grid voltage and A-phase current.
- 6. ELECTRICAL PROJECTS USING MATLAB/SIMULINK Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 For Simulation Results of the project Contact Us Gmail: asokatechnologies@gmail.com, Website: http://www.asokatechnologies.in 0-9347143789/9949240245 CONCLUSION: A new control structure for three-phase grid-connected voltage source inverters (VSI) with an LCL-filter is proposed. By using the instantaneous power control scheme and the proposed positive-sequence voltage detector, the current reference can be indirectly generated, which avoids the complex PLL. The effectiveness of the proposed system for three-phase grid- connected VSIs is demonstrated via simulation results, which show a significant improvement in both the steady state and transient behavior. The same behavior is experimentally verified. The fast dynamic response to a reference step is not affected by the inclusion of additional control loops. Good performance is guaranteed even under unbalanced and distorted grid voltages. REFERENCES: [1] X. Wang, J. M. Guerrero, F. Blaabjerg, and Z. Chen, “A review of power electronics based microgrids,” Journal of Power Electronics, Vol. 12, No. 1, pp. 181-192, Jan. 2012. [2] S. Peng, A. Luo, Y. Chen, and Z. Lv, “Dual-loop power control for single-phase grid- connected converters with LCL filters,” Journal of Power Electronics, Vol. 11, No. 4, pp. 456- 463, July. 2011. [3] F. Blaabjerg, R. Teodorescu, M. Liserre, and A. V. Timbus, “Overview of control and grid synchronization for distributed power generation systems,” IEEE Trans. Ind. Electron., Vol. 53, No. 5, pp. 1398-1409, Oct. 2006. [4] R. Inzunza, T. Sumiya, Y. Fujii, and E. Ikawa, “Parallel connection of grid-connected LCL inverters for MW-scaled photovoltaic systems,” in Proc. IEEE IPEC, pp. 1988-1993, 2010. [5] T. Noguchi, H. Tomiki, S. Kondo, and I. Takahashi, “Direct power control of PWM converter without power-source voltage sensors,” IEEE Trans. Ind. Appl., Vol. 34, No. 3, pp. 473-479, Mar./ Jun. 1998.