Performance Improvement of Single-Phase Grid–Connected PWM Inverter Using PI with Hysteresis Current Controller BTech EEE Academic projects

 

ABSTRACT:

Now a day’s distributed generation (DG) system uses current regulated PWM voltage-source inverters (VSI) for synchronizing the utility grid with DG source in order to meet the following objectives: 1) To ensure grid stability 2) active and reactive power control through voltage and frequency control 3) power quality improvement (i.e. harmonic elimination) etc. In this paper the comparative study between hysteresis and proportional integral (PI) with hysteresis current controller is presented for 1-Φ grid connected inverter system. The main advantage of hysteresis+PI current controller is low total harmonic distortion (THD) at the point of common coupling (PCC) at a higher band width of the hysteresis band. The studied system is modeled and simulated in the MATLAB Simulink environment.

KEYWORDS:

  1. Hysteresis current controller
  2. PI controller
  3. Point of common coupling (PCC)
  4. DG
  5. Utility grid
  6. THD

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

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Fig.1. Block diagram for hysteresis current control of single-phase grid connected VSI

EXPECTED SIMULATION RESULTS:

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 Fig.2. Simulation result of the hysteresis current controller for fixed band (a) grid voltage (Vg) and grid current (Io) (b) reference current, actual current and current error(c) switching frequency

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Fig.3. Simulation result of the hysteresis+PI current controller for fixed band (a) grid voltage (Vg) and grid current (Io) (b) reference current, actual current and current error(c) switching frequency

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Fig.4. Simulation result of hysteresis current controller for change in band (a) grid current (b) switching frequency(c) current error

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Fig.5. Simulation result of hysteresis+PI current controller for change in band (a) grid current (b) switching frequency(c) current error

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Fig.6. THD of grid current for hysteresis current controller (a) HB=1(b)HB=3(c)HB=5

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Fig.7. THD of grid current for hysteresis+PI current controller (a) HB=1(b) HB=3(c) HB=5

CONCLUSION:

From the study we observed that, hysteresis+PI current controller can enable to reduce switching frequency even if the band width increased without any significant increase in the current error. Hence it provides considerably less THD at higher band width as compared to conventional hysteresis current controller.

REFERENCES:

[1] Blaabjerg, F.; Teodorescu, R.; Liserre, M.; Timbus, A.V., “Overview of Control and Grid Synchronization for Distributed Power Generation Systems” IEEE Transactions on Industrial Electronics,Vol.:53 , Issue:5, Page(s): 1398 – 1409, 2006

[2] F.Blaabjerg, Zhe Chen, and S.B. Kjaer. “Power Electronics as Efficient Interface in Dispersed Power Generation Systems”, IEEE Transactions on Power Electronics, 19(5):1184–1194, Sept. 2004.

[3] Ho, C.N.-M.,Cheung, V.S.P.,Chung, H.S.-H.” Constant-Frequency Hysteresis Current Control of Grid-Connected VSI without Bandwidth Control”,IEEE Trans. on Power Electronics, TPEL 2009,Volume: 24, no. 11 ,, Pp:2484 – 2495, 2009

[4] Rahman, M.A.; Radwan, T.S.; Osheiba, A.M.; Lashine, A.E.; “Analysis of Current Controllers for Voltage-Source Inverter” IEEE Trans. On Industrial Electronics, Volume: 44 , no. 4 , Pp. 477 – 485, ,1997

[5] Tekwani, P.N, Kanchan, R.S., Gopakumar, K.; “Current-error spacevector- based hysteresis PWM controller for three-level voltage source inverter fed drives” Proceedings of Electric Power Applications, IEE Volume: 152 , Issue: 5, Pp: 1283 – 1295,2005

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