Papers by Keyword: Harmonics

Abstract: In most industrial plants, power quality is a major issue which hinders productivity and efficiency of the plants due to the use of semiconductor based loads and non-linear loads. As a result, to address the power quality problems in these industries, specialized power devices such as the Unified Power Quality Conditioner (UPQC), can be installed at the customer's location to resolve practically all power quality issues. UPQC consist of a series of active power filters (APF) which mitigate voltage quality issues and shunt active power filters which are used to reduce current quality issues, like harmonics and reactive power burdens. This paper, therefore presents an investigation and assessment of the power quality problems associated with Bahir Dar Textile Share Company. This was achieved by examining the voltage and current harmonic levels of various types of loads using PI and fuzzy logic controllers by measuring the level of total harmonic distortion (THD) with and without the insertion of the UPQC. The novelty of this paper is the implementation of the controller based customized UPQC for power factor and reactive power compensation. It was observed that by designing the system without and with UPQC, the results of the FFT analysis show that the fuzzy logic controller (FLC) reduced the harmonics level of the load voltage and current by 1.10% and 2.14% respectively. Generally, harmonics was alleviated by 90%, reactive power was reduced by 20%, and power factor was improved by 33%. Hence, the proposed UPQC is capable of holding the voltage and current harmonics levels within the acceptable limit, which satisfies the standards imposed by IEEE 519-1995.

Abstract: Because of The low complexity of passive filters (PF) compared to the active filter, their high efficiency, their ease of installation and their different topologies,theyremained the devices required in the power system. In order to minimize the harmonic distortion produced by the large industrial loads, harmonic filters should, therefore, be designed with the utmost rigor, because a poorly designed filter may amplify the undesired harmonics. The determination of the PFcomponents requires both adetailed study ofthe power system parameters, which influence the efficiency and economic viability of the harmonic compensation and the reactive power required by the load.This article studies the use of the Cuckoo optimization algorithm (COA), in order to designpassive filters with an improved power quality and reduced cost. The optimal filters are connected concurrently to the power system so that each individual Harmonic distortion respects the recommended limits. The results show that the optimized (PF) is effective, and has a lower cost.

Abstract: This paper presents a modified hybrid Controller based on instantaneous power-fuzzy controller (IPFLC) for a shunt active power filter (SAPF). The current produced by the AC source is polluted by harmonics injected by the non-linear loads. The supply system requires filtering by suppressing harmonic currents to improve power quality at interface bus. The filtering system consists of an LC filter and a SAPF. The proposed IPFL Controller for the SAPF is based on a combination of the p-q instantaneous power and the fuzzy logic strategy. In this part, two cases are studied, first the active filter is connected only to a capacitor by its dc side, and second case where the active filter is connected to a photovoltaic source or to a battery. The effectiveness, robustness and the dynamic speed of the proposed controller is validated and assessed using dynamic digital simulation. Digital Simulation results validated also the effectiveness of the active filter scheme with modified controller in reducing the source current THD from 25.87% to 0.83% which largely meets the standards of IEEE STD and International Electro-technical Commission (IEC). Digital Simulation and validation used MATLAB-SIMULINK Software Environment.

Abstract: As small wind turbines are increasingly used, the assessments of power quality may thus become paramount. Unlike the large-scale wind turbines which are optional required to perform power quality measurements during production certification stage; however the power quality measurements are often neglected in small wind turbines since they are not requested on the certain of national grid codes at low-voltage distribution system level. Considering the high penetrations of small wind turbines may be connected to the future urban electric network, the paper performs the power quality on-site measurements of a horizontal axle small wind turbines. The issues may include the discussion of measurement system structure, the description of measurement method, and the analysis of wind turbine power characteristic, voltage/current trends, harmonics and flicker phenomena. The measured data collected in the study will valuable for the further analysis of power systems connected with the small wind turbines.

Abstract: The present article describes the analysis of electromagnetic field in an induction MHD-stirrer for liquid metals with the account of transverse di-mensions of the inductor and bath with melt. The parameters of the equivalent circuit of a MHD-stirrer and its electromagnetic characteristics have been defined.

Abstract: The present article describes the analysis of electromagnetic field carried out by an analytical method in the system inductor–bath with melt (liquid metal) taking into account different winding characteristics of the inductor. It also defines integral and differential characteristics of the system for the most widespread windings of an MHD-stirrer.

Abstract: A conventional electrical distribution system are not designs to deal with harmonics because at that time the linear load conquer the consumer demand. Over the years with growing use of nonlinear load such as personal computer can contribute to harmonics current occur on electrical distribution system. With the presence of harmonics current on electrical distribution system leads in degradation of system performance. Therefore necessary actions are needed in order to minimize harmonics effect. The predominant harmonics should be eliminated from electrical distribution system such as 5^th and 7^thof harmonics current component. The eliminating process is achieved by implementing the current phase shifting technique on new concept of modern electrical distribution system at Makmal Komputer 3, Faculty of Electrical Engineering, UiTM Pulau Pinang.

Abstract: Power quality is becoming a concern in modern electrical network due to complexity of the system. To improve power quality, there needs to be analysis and research on complex power quality events systematically. Disturbances in distribution system, including sag/swell, transient, harmonic, voltage notch, and flicker that affect power quality are simulated in this research work. The comprehensive set of models are developed in PSCAD with minimum blocks and settings without compromising the essence of power quality events. This research work aims to introduce the power quality events to electrical engineering students, as well as reinforce understanding of power quality disturbances in distribution system through interactive simulation approach.

Abstract: This paper reviews neural network control algorithm for power quality improvement. Further, this paper focuses on the neural network control algorithm for DSTATCOM and surveys its area of improvements. Various architectures of Neural Network such as Adaline/Widrow-Hoff, perceptron, Back-propagation (BP), Hopfield, and Radial Basis Function (RBF) that has been reviewed in this paper. It is found that many researches on theoretical works and single phase system are widely performed, whereas its application on distribution network for three phase system is hardly found. Even so much improvement that have been done by researchers theoretically to improve the drawbacks of Neural Network controller; there are still wide gaps for verification through experimental implementation and industrial applications.

Abstract: A novel algorithm for a single-phase active power filter (APF) is proposed in this paper. The proposed algorithm avoids the use of main voltage signal in the calculation of reference compensation current. Therefore, the mains current after compensation is still a pure sinusoidal waveform even when the mains voltage is distorted. A novel circuit for detecting the amplitude of the real part of the fundamental load current is not more than 1/4 cycle. Its transient response is superior to the other conventional techniques. In addition, the proposed algorithm can compensate for the power factor and suppress the harmonics of nonlinear loads. Finally, some experimental results are presented for verification.