A Hysteresis Current Controller for Grid-Connected Inverter with Reduced Losses

ABSTRACT:

In this paper, a hysteresis current controller with reduced losses for three-phase grid-connected inverter is proposed. In the proposed hysteresis current controller, one of the inverter phase is clamped to the positive or negative inverter buses depending on the polarity of the phase current. Totally, each inverter phase is clamped for the duration of one third of the fundamental output period. As the inverter phase is inactive when the current is the highest, the switching losses are reduced. Simulation and experimental results are included to show the effectiveness of the proposed controller.

 

KEYWORDS:

  1. Current controller
  2. Hysteresis
  3. Grid-connected inverter,
  4. Losses
  5. Clamped

 

SOFTWARE: MATLAB/SIMULINK

  

CIRCUIT DIAGRAM:

Power controller of grid-connected inverter

Fig. 1. Power controller of grid-connected inverter

 

EXPECTED SIMULATION RESULTS:

conventional hysteresis current controller

Fig. 2. Output current and switching pattern of: (a) conventional hysteresis current controller, (b) proposed hysteresis current controller

 proposed hysteresis current controller

Fig. 3. Output current and switching pattern of: (a) conventional hysteresis current controller, (b) proposed hysteresis current controller

 

CONCLUSION:

A simple hysteresis current controller with reduced losses has been proposed in this paper. In the proposed current controller, one of the inverter phase is clamped to the positive or negative DC bus, depending on the polarity, when the magnitude of the current is the greatest. This lead to reduction of the average switching frequency as well as the switching losses. Simulation and experimental results have shown that the proposed hysteresis controller is able to reduce the switching losses without sacrificing the output current waveform.

 

REFERENCES:

  • Jain and V. Agarwal, “A Single-Stage Grid Connected Inverter Topology for Solar PV Systems With Maximum Power Point Tracking,” IEEE Trans. Power Electron., vol. 22, no. 5, pp. 1928–1940, 2007.
  • Mohseni and S. M. Islam, “A new vector-based hysteresis current control scheme for three-phase PWM voltage-source inverters,” IEEE Trans. Power Electron., vol. 25, no. 9, pp. 2299–2309, 2010.
  • P. Kazmierkowski and M. A. Dzieniakowski, “Review of currentregulation techniques for three-phase PWM inverters,” Proc. IECON’94 – 20th Annu. Conf. IEEE Ind. Electron., vol. 1, pp. 567–575, 1994.
  • Zhang and H. Lin, “Simplified model predictive current control method of voltage-source inverter,” 8th Int. Conf. Power Electron. – ECCE Asia, pp. 1726–1733, 2011.
  • C. Hua, C. W. Wu, and C. W. Chuang, “A digital predictive current control with improved sampled inductor current for cascaded inverters,” IEEE Trans. Ind. Electron., vol. 56, no. 5, pp. 1718–1726, 2009.

Three-phase grid connected PV inverters using the proportional resonance controller

2016 IEEE

ABSTRACT

The development in grid connected three phase inverter has increased the importance of achieving low distortion and high quality current waveform. This paper describes a method of reducing current ripple in a three phase grid connected inverter utilizing Proportional Resonance (PR) controller. The effectiveness of the PR current controller is demonstrated by comparing its performance with that of the Proportional Integral (PI) controller. Simulation and experimental results show that Proportional Resonance (PR) controller achieves better reduction in total harmonic distortion (THD) in the current signal spectrum.

 

KEYWORDS

  1. Grid-connected inverter
  2. LCL filter
  3. PI controller
  4. PR controller.

 

SOFTWARE:MATLAB/SIMULINK

  

BLOCK DIAGRAM:

block diagram

Fig.1. PI controller in synchronous reference scheme.

Fig. 2 PR controller in stationary reference control

SIMULATION RESULTS

Fig.3. The phase grid voltage

Fig.4. The phase current waveform using PI controller

 

Fig.5 The phase current waveform using Proportional resonance  controller

Fig.6. The FFT of the phase current waveform using PI controller

Fig.7. The FFT of the phase current waveform using Proportional Resonance controller

 

CONCLUSION

This paper has considered the impact of the current control scheme of a three-phase grid-connected inverter under normal and abnormal grid conditions using PI and PR controllers. In particular, this work has compared the performance of the industrially accepted PI controller, and the emerging PR controller which is popular in grid connected renewable energy applications. In keeping with the claims of other literature, simulation studies have confirmed that the PR controller shows better performance under normal operating conditions. There is no steady state error output, and the harmonic content of the current waveform is very low. Moreover, in this paper, the effect of grid voltage dips on the performance of the grid connected inverter was considered. Whilst the PI controller demonstrates very good performance, the Proportional Resonance controller offers superior output power regulation, and improved power quality performance. Overall, it suggests that the PR controller is better suited in the event of grid faults, or operation in weak grid environments.

 

REFERENCES

  1. Wuhua and H. Xiangning, “Review of Nonisolated High-Step-Up DC/DC Converters in Photovoltaic Grid-Connected Applications,” IEEE Trans. Ind Electron., vol. 58, pp. 1239-1250, 2011.
  2. Atkinson, G. Pannell, C. Wenping, B. Zahawi, T. Abeyasekera, and M. Jovanovic, “A doubly-fed induction generator test facility for grid fault ride-through analysis,” Instrumentation & Measurement Magazine, IEEE, vol. 15, pp. 20-27, 2012.
  3. Cecati, A. Dell’Aquila, M. Liserre, and V. G. Monopoli, “Design of H-bridge multilevel active rectifier for traction systems,” Industry Applications, IEEE Transactions on, vol. 39, pp. 1541-1550, 2003.
  4. Hassaine, E. Olias, J. Quintero, and V. Salas, “Overview of power inverter topologies and control structures for grid connected photovoltaic systems,” Renewable and Sustainable Energy Reviews, vol. 30, pp. 796-807, 2014.
  5. Nicastri and A. Nagliero, “Comparison and evaluation of the PLL techniques for the design of the grid-connected inverter systems,” in Industrial Electronics (ISIE), 2010 IEEE International Symposium on, 2010, pp. 3865-3870.

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