Harmonic Current Filtering Research Articles

A Hybrid Compensator for Unbalanced AC Distribution System With Renewable Power

A hybrid compensator with a new coordinated control is proposed for mitigating power quality aspects and integration of renewable power in an unbalanced three-phase four-wire distribution system. The proposed compensator comprises of thyristor switched capacitor (TSC) banks, delta connected thyristor controlled reactor (TCR), a 3rd and a 5th harmonic tuned passive LC filter & a low rating three-phase four-wire D-STATCOM. The TSC-TCR operates asymmetrically for the base var compensation and also eliminates negative sequence current during unbalanced loading at the point of common coupling (PCC). The D-STATCOM works in coordination with the TSC-TCR and the passive filters to compensate fundamental var, zero sequence current, voltage flicker & 7th harmonic currents at the PCC. The D-STATCOM thus serves as a supportive var compensator as well as an active filter in selective harmonic compensation mode, thereby improving the var compensation and harmonic current filtering at the PCC. A new coordination control system is proposed to control the operation of the D-STATCOM which is also employed to integrate a PV source & a doubly fed induction generator (DFIG) based wind energy conversion system (WECS) to the PCC. This scheme with grid connected and islanded mode of operation using D-STATCOM exhibits low-voltage ride-through capabilities. Further, the chance of resonance of the passive filters used with source inductance is eliminated in the proposed scheme. Simulation results show that the proposed hybrid system effectively compensates var, negative & zero sequence current, reduces voltage flicker and harmonic currents at PCC.

Genetic Rules Induction Fuzzy Inference System for Classification and Regression Application in Energy Industry

Genetic fuzzy system encompasses genetic algorithm and fuzzy logic. It divulges the advantage of optimization with ease of understanding for classification and regression of energy performance of buildings, transformer, and harmonic current in energy industry. This paper presents development of a new rules induction algorithm namely genetic rules induction fuzzy inference system for classification and regression (GRIFISCnR) that combines genetic algorithm with fuzzy logic to facilitate efficient design of building, transformer and harmonic current filter in energy industry using Pittsburgh approach. GRIFISCnR possesses the rules induction capability over other algorithms for multi-class classification and regression problems without compromising on interpretability and accuracy. It manages to strike a balance between interpretability and accuracy, and yield better accuracy with lesser number of rules. It is easier to interpret and understand fuzzy rules as compared to numerical numbers.

A New Harmonic Reduced Three-Phase Thyristor-Controlled Reactor for Static VAr Compensators

A new thyristor-controlled reactor scheme is presented in this paper, in which the total bank is split into one Δ- and one Y-connected reactor bank with the addition of a low-rating zig-zag autotransformer, instead of the conventional scheme using a Δ-connected reactor bank with a harmonic current filter. This arrangement prevents the triplen harmonics generated by the Y bank from entering into the supply system and at the same time, the combination results in cancellation of some major characteristic harmonics from the source current. Thus, without using any additional filters or phase-shifting two-winding transformer, this scheme facilitates reactive power control over a wide range and also meets the requisite harmonics standards. The scheme is simple and provides a cost-effective solution to the VAr compensation problem. Simulation and experimental results are provided to validate the proposed concept.

Optimal planning of passive harmonic filters using hybrid differential evolution considering variation of system parameters

SUMMARY This paper presents an optimal planning of passive harmonic filter using the hybrid differential evolution method considering variation of system impedance, harmonic current sources and filter tuning points. The proposed method minimizes an objective composed of the total harmonic distortion of current and voltage, selects different filters topologies, and determines their optimal parameters and tuned points under a constant cost. The harmonic currents and voltages in a power system are expressed as probabilistic models which are obtained using the statistical simulation method. Monte-Carlo simulation is employed to verify the accuracy of the obtained probabilistic models. The method proposed is applied to solve the harmonic problems in a practical chemical plant, and the results show that the proposed method is effective for passive filter planning in industrial distribution systems. Copyright © 2012 John Wiley & Sons, Ltd.