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Friday 27 November 2015

TS-Fuzzy-Controlled Active Power Filter for Load Compensation



ABSTRACT:
This paper describes the application of Takagi–Sugeno (TS)-type fuzzy logic controller to a three-phase shunt active power filter for the power-quality improvement and reactive power compensation required by a nonlinear load. The advantage of fuzzy logic control is that it does not require a mathematical model of the system. The application of the Mamdani-type fuzzy logic controller to a three-phase shunt active power filter was investigated earlier but it has the limitation of a larger number of fuzzy sets and rules. Therefore, it needs to optimize a large number of coefficients, which increases the complexity of the controller. On the other hand, TS fuzzy controllers are quite general in that they use arbitrary input fuzzy sets, any type of fuzzy logic, and the general defuzzifier. Moreover, the TS fuzzy controller could be designed by using a lower number of rules and classes. Further, in this paper, the hysteresis current control mode of operation is implemented for pulsewidth-modulation switching signal generation. Computer simulation results show that the dynamic behavior of the TS fuzzy controller is better than the conventional proportional-integral (PI) controller and is found to be more robust to changes in load and other system parameters compared to the conventional PI controller.

KEYWORDS:

1.      Dynamic behavior of the controller
2.       Power quality improvement
3.       Shunt active power filter
4.       Takagi–Sugeno (TS) fuzzy logic controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:
                  


 Fig. 1. Basic compensation principle of APF.

EXPECTED SIMULATION RESULTS:

        
                     

Fig. 2. Source voltage
                                      

Fig. 3. Source current when the compensator is not connected.

                                      



Fig. 4. Source current: PI controller.
                                               

Fig. 5. Source current: TS fuzzy controller
                             
      

Fig. 6. Load current.
                                    


Fig. 7. DC capacitor voltage: load is increased at 0.3 s.

                                 
                    

Fig. 8. Source current: PI controller.


                                               

Fig. 9. Source currents: TS fuzzy controller
                                                   

Fig. 10. Load current.

           
                                     


Fig. 11. DC capacitor voltage: load is reduced at 0.3 s.


                                              


Fig. 12. Source current: PI controller
                                                    


Fig. 13. Source currents: TS fuzzy controller.

                                                   


Fig. 14. THD in source currents.

CONCLUSION:

A TS fuzzy-logic-controlled shunt active power filter has been developed to improve the performance of controller for load compensation. The performance of the TS fuzzy logic controller is compared with the conventional PI controller. The harmonic elimination process is simple, and it is implemented by sensing line currents only. From the simulation results, it is clear that the dc voltage excursion of the TS fuzzy controller is better than the conventional PI controller under various load conditions as well as filter parameter variations. The dc-link voltage settles approximately within two cycles for the large change in load and also the excursion in voltage is less compared to the PI controller. For the changes in filter parameters (and), the performance of the TS fuzzy controller remains the same. Hence, the TS fuzzy controller is quite robust for system parameter variations. The THD of the source current after compensation is well below the permissible limit of 5%. TS fuzzy control is better than the Mamdani type of fuzzy control in the sense that it requires only two numbers of fuzzy sets, four rules, and five numbers of coefficients to be optimized compared to seven fuzzy sets, 49 rules, and 17 coefficients used for the Mamdani type used in [11]. Hence, the TS fuzzy controller is a good candidate for improving the dynamic performance of a compensator and eliminating the harmonics.

REFERENCES:

[1] H. Akagi, Y. Kanazawa, and A. Nabae, “Instantaneous reactive power compensators comprising switching devices without energy storage components,” IEEE Trans. Ind. Appl., vol. IA-20, no. 3, pp. 625–630, May/Jun. 1984.
[2] F. Z. Peng, H. Akagi, and A. Nabae, “Study of active power filters using quad series voltage source PWM converters for harmonic compensation,” IEEE Trans. Power Electron., vol. 5, no. 1, pp. 9–15, Jan. 1990.
[3] W. M. Grady,M. J. Samotyj, and A. H. Noyola, “Survey of active power line conditioning methodologies,” IEEE Trans. Power Del., vol. 5, no. 3, pp. 1536–1542, Jul. 1990.
[4] B. Singh, A. Chandra, and K. Al-Haddad, “Computer-aided modeling and simulation of active power filters,” Elect. Mach. Power Syst., vol. 27, pp. 1227–1241, 1999.

[5] K. Chatterjee, B. G. Fernandes, and G. K. Dubey, “An instantaneous reactive volt-ampere compensator and harmonic suppressor system,” IEEE Trans. Power Electron., vol. 14, no. 2, pp. 381–392, Mar. 1999..