Voltage Sag/Swell Compensation Using Z-source Inverter DVR based on FUZZY Controller

ABSTRACT:

The power quality necessity is one of the serious issues for power organizations and their clients. The examination of intensity unsettling influence attributes and discovering answer for the power quality issues have brought about an expanded enthusiasm for power quality. The most concerning aggravations influencing the nature of the power in the conveyance framework are voltage list/swell. The DVR is utilized to alleviate the voltage list/swell on touchy load. In this paper Z-source inverter (ZSI) based DVR is proposed to improve the voltage rebuilding property of the framework. The ZSI utilizes a LC impedance lattice to couple control source to inverter circuit and readies the likelihood of voltage buck and lift by shortcircuiting the inverter legs. Furthermore a fluffy rationale control plot for Z-source inverter based DVR is proposed to acquire wanted infusing voltage. Displaying and reproduction of the proposed DVR is actualized in MATLAB/SIMULINK stage.

 

BLOCK DIAGRAM:

Fig. 1 DVR general configuration

 

EXPECTED SIMULATION RESULTS:

Fig.2Three phase voltage at load point during three phase fault without DVR

Fig 3. Three phase voltage by DVR

Fig.4Three phase compensated voltage with DVR

Fig.5comparison of performance of DVR using Z-source inverter during fault condition

Fig.6Three phase voltage at load point during three phase fault with DVR and PI controller

Fig.7Three Phase voltage at load point during three phase fault with DVR and PI and Fuzzy controller

 

CONCLUSION:

DVR fills in as a successful custom power gadget for relieving voltage hang/swell in the dispersion framework. If there should arise an occurrence of outside aggravations the proposed DVR infuses suitable voltage part to powerfully address any deviation in supply voltage so as to keep up adjusted and steady load voltage at ostensible esteem. In this paper Z – source inverter based DVR alongside fluffy controller is displayed and the equivalent is introduced in the conveyance framework to give required load side pay. The reenactment of the DVR alongside the proposed controller is completed utilizing MATLAB/SIMULINK stage. The reenactment results demonstrates that the execution of Z – source inverter based DVR alongside fluffy controller is better contrasted with PI controller.

A New Variable-Speed Wind Energy Conversion System Using Permanent-Magnet Synchronous Generator and Z-Source Inverter

ABSTRACT:

With the growth of wind energy conversion systems (WECSs), various technologies are developed for them. Permanent-magnet synchronous generators (PMSGs) are used by these technologies due to special characteristics of PMSGs such as low weight and volume, high performance, and the elimination of the gearbox. In this paper, a new variable-speed WECS with a PMSG and Z-source inverter is proposed. Characteristics of Z-source inverter are used for maximum power tracking control and delivering power to the grid, simultaneously.  Two control methods are proposed for delivering power to the grid: Capacitor voltage control and dc-link voltage control. Operation of system with these methods is compared from the viewpoint of power quality and total switching device power (TSDP). In addition, TSDP, current ripple of inductor, performance, and total harmonic distortion of grid current of proposed system is compared with traditional wind energy system with a boost converter.

 

BLOCK DIAGRAM:

Fig. 1. Proposed PMSG-based WECS with Z-source inverter.

EXPECTED SIMULATION RESULTS:

Fig. 2. DC voltage and optimum rotor speed relation: simulated and approximated and calculated (actual).

Fig. 3. Wind speed variation.

Fig. 4. PMSG rotor speed (capacitor voltage control).

Fig. 5. Maximum mechanical power of turbine and the extracted mechanical power from turbine (capacitor voltage control).

Fig. 6. Capacitor voltage (capacitor voltage control).

Fig. 7. Active and reactive powers (capacitor voltage control).

Fig. 8. Active power delivered to the grid and extracted mechanical power

(capacitor voltage control).

Fig. 9. Inductor current of Z-source inverter (capacitor voltage control).

Fig. 10. Input voltage of Inverter (Vi ) (capacitor voltage control).

Fig. 11. PMSG rotor speed (dc-link voltage control).

Fig. 12. The maximum mechanical power of turbine and the extracted mechanical  power from turbine (dc-link voltage control).

Fig. 13. Active power delivered to the grid and extracted mechanical power (dc-link voltage control).

Fig. 14. Capacitor voltage (dc-link voltage control).

Fig. 15. Input voltage of Inverter (Vi ) (dc-link voltage control).

Fig. 16. DC-link voltage across the rectifier.

 

Fig. 17. DC-link voltage across the Z-source inverter.

Fig. 18. Inductor current of Z-source inverter.

Fig. 19. Inductor current of Z-source inverter (zoomed).

Fig. 20. Grid current in proposed WECS.

Fig. 21. Spectra of grid current in proposed WECS.

 

Fig. 22. Inductor current of boost converter (zoomed).

Fig. 23. Inductor current of boost converter.

Fig. 24. Grid current in traditional WECS without dead time.

Fig. 25. Spectra of grid current in traditional WECS without dead time.

Fig. 26 Grid current in traditional WECS with dead time.

Fig. 27. Spectra of grid current in traditional WECS with dead time.

Fig. 28. Active power delivered to the grid in conventional and proposed WECSs.

Fig. 29. Efficiency of conventional and proposed WECSs.

CONCLUSION:

In this paper, a PMSG-based WECS with Z-source inverter is proposed. Z-source inverter is used for maximum power tracking control and delivering power to the grid, simultaneously. Compared to conventional WECS with boost converter, the number of switching semiconductors is reduced by one and reliability of system is improved, because there is no requirement for dead time in a Z-source inverter. For active power control, two control methods: capacitor voltage control and dc-link voltage control is proposed and compared. It is shown that with dc-link voltage control method, TSDP is increased only 6% compared to conventional system, but there is more power fluctuations compared to capacitor voltage control. With capacitor voltage control TSDP in increased 19% compared to conventional system. It was also shown that due to elimination of dead time, the THD of proposed system is reduced by 40% compared to conventional system by 5mS dead time. Finally, with same value of passive components, inductor current ripple is the same for both systems.