Voltage and Frequency Control of a Stand-alone Wind-Energy Conversion System Based on PMSG

ABSTRACT:

This paper presents a control strategy for a standalone wind-energy conversion system using Permanent Magnet Synchronous Generator (PMSG). The presented control strategy aims at regulating the load voltage in terms of magnitude and frequency under different operating conditions including wind speed variation, load variation and the unbalanced conditions. The wind generating-system under study consists of a wind turbine, PMSG, uncontrolled rectifier, DC-DC boost converter and voltage source inverter. The presented control strategy is based firstly upon controlling the duty cycle of the boost converter in order to convert the variable input dc-voltage, due to different operating conditions, to an appropriate constant dc voltage. Hence, a sinusoidal pulse width modulated (SPWM) inverter is used to regulate the magnitude and frequency of the load voltage via controlling the modulation index. In order to verify the performance of the employed wind generating-system, a sample of simulation results is obtained and analyzed. The presented simulation results show the effectiveness of the employed control strategy to supply the load at constant voltage and frequency under different operating conditions.

KEYWORDS:

  1. Wind turbine
  2. PMSG
  3. Voltage and frequency control

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1.Complete structure of the stand-alone wind-energy conversion system

EXPECTED SIMULATION RESULTS:

Fig. 2.Effect of wind-speed variation on the generated voltage and frequency: a) Wind speed b) generated line voltage c) frequency of the generated voltage

Fig. 3. DC-link voltage

Fig. 4. Load voltage and current during different periods of wind-speed

variation a) Effective value of the load voltage b) Instantaneous three-phase

load-current waveforms

Fig. 5. Effect of load variation on the generated voltage and frequency at constant wind speed a) generated line voltage b) frequency of the generated voltage

Fig. 6. Load voltage and current during different periods of load variations a) Effective value of load voltage during different loads b) Instantaneous threephase load-current waveforms

Fig. 7 DC Link Voltage during balanced and unbalanced

Fig. 8. Effective value of the load voltage during both balanced and

unbalanced loading condition

Fig. 9. Load current of each phase during both balanced and unbalanced loading conditions (a) Instantaneous waveforms (b) Effective value

CONCLUSION:

This paper has presented a control strategy of a stand-alone wind-driven Permanent Magnet Synchronous Generator (PMSG) in order to regulate the magnitude and frequency of the load voltage under different operating conditions. In order to ensure the validity of the presented control strategy, the performance characteristics of the wind-generating system has been studied and discussed under three different operating conditions; wind-speed variation, load variation and unbalance operating condition. The presented simulation results have verified the effectiveness of the control strategy to maintain the load voltage and frequency at a constant level under different operating conditions. This has been achieved by controlling the duty cycle of the employed DC-DC boost converter in order to maintain the DC-link voltage constant at a predetermined value. In addition, the magnitude and frequency of the load voltage has been maintained constant via controlling the modulation index of the load-side SPWM inverter. A constant modulation index has been used in the case of balanced loading conditions. However, different modulation index for each phase has been used in case of unbalanced loading conditions.

REFERENCES:

[1] Aditya Venkataraman, Ali Maswood, Nirnaya Sarangan, Ooi H.P. Gabriel “An Efficient UPF Rectifier for a Stand-Alone Wind Energy Conversion System,” IEEE Trans. on industry applications, vol. 50, NO.2, Marsh/April. 2014

[2] Y. Izumi, A. Pratap, K. Uchida, A. Uehara, T. Senjyu, A. Yona, “A control method for maximum power point tracking of a PMSG-based WECS using online parameter identification of wind turbine,” Proc. Of the IEEE 9th International Conf. on Power Electronics and Drives Systems, Singapore, 5–8 Dec. 2011, pp. 1125–1130.

[3] M. Singh, A. Chandra, B. Singh, “Sensorless power maximization of PMSG based isolated wind-battery hybrid system using adaptive neurofuzzy controller,” IEEE Ind. Appl. Soc. Annual Meeting, 2010, pp. 1-6.

[4] Nishad Menddis, Kashem M. Muttaqi, Sarath Perara “Management of Battery-Supercapacitor Hybrid Energy Storage and Synchronous Condenser for Isolated Operation of PMSG Based Variable-speed wind Turbine Generating Systems“IEEE Trans. ON SMART GRID, vol. 5, NO.2, MARCH 2014

[5] Luminita BAROTE, Corneliu MARINESCU “Modeling and Operational Testing of an Isolated Variable Speed PMSG Wind Turbine with Battery Energy Storage,” Advances in Electrical and Computer Engineering, vol. 12, No. 2, 2012. For equivalent circuit of PMSG

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