Power Quality Improvement Using Intelligent Fuzzy Based Active Power Filter

OVERVIEW:

Use of power electronic converters with non linear loads produces harmonic currents and reactive power. A shunt active power filter provides an elegant solution to reactive power compensation as well as harmonic mitigation leading to improvement in power quality. However, the shunt active power filter with PI type of controller is suitable only for a given load. If the load is varying, the proportional and integral gains are required to be fine tuned for each load setting. The present study deals with fuzzy logic based controller for shunt active power filter. MATLAB Simulink is used to prove the results.

Keywords: Fuzzy, Active Filters, Power Quality.

I. POWER QUALITY IMPROVEMENT INTRODUCTION:

The active power filter is proved as the ultimate solution for mitigating harmonics and compensating reactive power developed by using non linear power electronic loads. As the ancient solution are faded out with detuning and fixed compensation effects, the active power filter is chosen with its flexibility to provide the compensating current for any adverse situations of supply and load. Many articles have been published in the area of active filters with PI controller. Some of them are [2], presented the instantaneous reactive power theory with comprising switching devices. Practically it didn't require any energy storage elements. The physical meaning of instantaneous reactive power was discussed in detail. [3] Proposed a new control technique for dc capacitor voltage. The active power filter with quad series voltage source PWM converter to suppress ac harmonics by injecting the compensating current was discussed. [4] Introduced the active power filter for three phase four wire system. The system had distinct advantages over the three single phase active power filters used at that time. Moran [5] proposed an active power filter which runs with a fixed switching frequency. Reactive power compensation was also achieved even without sensing the reactive power components which makes the circuit simpler. Singh B. et.al. [6] Presented a review article on active power conditioning technology. This article covers configurations, control strategies, selection of components, and related economic and technical considerations aiming to give a broad perspective on active power filters. Chatterjee K. et.at. [7] Proposed Instantaneous Reactive Power Volt - amp Compensation and Harmonic suppressor system without sensing Reactive Volt Ampere demand. It don' t involve in complicated controllogic. It is the Cycle-by-Cycle reference current control mode by regulating DC link voltage. The hardware PI and PLL based sine wave generator was used to implement control algorithm. Jain, Shailendra Kumar et.al. [8] Presented the designing of shunt active power filter with experimental validations for the proposed design. In this article the detailed designing procedure is adopted and reported. Jain S. K. et.al. [9] presented a fuzzy logic controller based shunt active power filter by sensing the line currents only unlike the conventional method of sensing the reactive currents. This article was concluded that the dynamic behavior of the fuzzy logic controller is better compared to that of PI controller with steady state and transient responses. Singh G.K. [10] proposed a simple fuzzy logic controller for mitigating harmonics and compensating reactive power. This article introduced the fuzziness in the limiter part and given an extensive result for the same with and without fuzzy logic.

This work will help to mitigating harmonics and compensating reactive power for unbalanced load also. Kishore Kumar Pedapenki et.al. [13] presented the fuzzy logic application to mitigate harmonics and to get good power quality. This article had the design and application of fuzzy logic with RL load and rectifier RL load with various firing angles as loads proved that the fuzzy logic was the better in all the cases compared to PI controller. By seeing the literature review, the fuzzy logic controller is superior in all aspects, it offers flexibility in taking linguistic inputs and can adapt to any system. This article presents application of the membership functions of the fuzzy based shunt Active Power Filters.

II. SYSTEM CONFIGURATION AND CONTROL

Fig. 1 presents the scheme of active filtering. The system consists of a three phase non linear load. The controllers are (a) PI controller (b) Fuzzy Controller. Fig. 2 fuzzy controller unit. Reference currents are the sinusoidal waves with frequency as the source voltage and the magnitude as the output of the controller. This can be done by dividing the each voltage wave with the maximum value to get the unit voltage wave and then multiplied with the output of the controller to get the required reference wave. This is compared with the actual currents and the error is process in the hysteresis controller. In present work, the performance of the shunt active power filter is evaluated with fuzzy logic controller (FLC). The effectiveness of FLC is investigated with different membership functions.

Fig.1 Shunt Active Power Filter

Fig.2 Fuzzy Control For Active Filter



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