Harmonic

About: Harmonic is a research topic. Over the lifetime, 44833 publications have been published within this topic receiving 495922 citations. The topic is also known as: overtone & partial.

Exact Model Order ESPRIT Technique for Harmonics and Interharmonics Estimation

Abstract: Harmonic, which is becoming more and more important day by day in the emerging power system, is one of the most critical power quality parameters. In this paper, the estimation of signal parameters via rotational invariance technique (ESPRIT)-based method is proposed with an accurate model order (the number of frequency components) estimate for power system harmonic and interharmonics detection. It is demonstrated that, even for high noise signal, the proposed algorithm is able to accurately estimate the number of frequency components present in the signal. The proposed method is capable of estimating the accurate values of frequency, amplitude, and phase angle of the distorted current or voltage signals for a wide range of sampling frequency and measurement noise. The robustness of the proposed method has been tested on several simulated synthetic signals and measured experimental signals for different nonlinear loads.

Harmonic and Negative-Sequence Current Control in an Islanded Multi-Bus MV Microgrid

Abstract: This paper presents a multifunctional control strategy for the autonomous operation of a multi-bus medium voltage (MV) microgrid under nonlinear and unbalanced load conditions. The main objective is to effectively compensate the harmonic currents of nonlinear loads using electronically-coupled distributed generation (DG) units. The proposed control strategy consists of a multi proportional resonant controller (MPRC) with adjustable resonance frequency and a harmonic impedance controller (HIC). The MPRC and HIC are, respectively, proposed to regulate the microgrid voltage and to share the harmonic currents of the nonlinear loads among the DG units. A conventional droop scheme is also employed to share the average powers of the loads between the DG units. Moreover, a virtual negative-sequence impedance control loop is augmented to the proposed control system to compensate the negative-sequence currents of the unbalanced loads. The proposed strategy minimizes the flow of harmonic and negative-sequence currents in the MV lines of the microgrid by local compensation of harmonic and negative-sequence currents of the feeders. The performance of the proposed control scheme is verified by using digital time-domain simulation studies in the PSCAD/EMTDC software environment.

Coherent control of high-order harmonics with chirped femtosecond laser pulses.

Abstract: High-order harmonics were coherently controlled using chirped femtosecond laser pulses for the production of sharp and strong harmonics. As the laser intensity was increased above the saturation intensity for optical-field ionization, the laser chirp needed to suppress harmonic chirp in the plateau region changed from positive to negative. We showed that the modification of a laser chirp condition in a rapidly ionizing medium should be included for the proper coherent control of high-order harmonics, necessitating the integral treatment of the interaction between atoms and a driving laser pulse.

Optimal multiobjective design of hybrid active power filters considering a distorted environment

Abstract: The development of new passive, active, and hybrid filtering techniques is important; and the issues of higher quality, reduced complexity, higher efficiency, and lower cost are important conditions that need to be addressed with regard to the expected stringent trends in power quality obligations. This paper suggests a new approach for the optimal sizing of hybrid active power filter (HAPF) parameters, which is presented for three-phase industrial power systems. Hybrid filter topology can be used to compensate harmonic currents, as well as for power factor corrections, without concern for importing and exporting harmonics, or simply the series and parallel resonance that may occur. The new trend in harmonic power filter design is not to obtain the best solution from a single objective optimization but to obtain a good compromise solution accomplished under other conflicting objectives. Fortran Feasible Sequential Quadratic Programming is used to determine the proposed filter optimal sizing to minimize the total voltage harmonic distortion as the main objective function, where maintaining the load power factor at an acceptable limit is desired. If the total harmonic voltage distortion achieves the specified goal, then the objective is redirected into minimizing the resultant voltage and current total harmonic distortions. The optimal design of the HAPF is analyzed by means of three case studies.

Design and performance of active power filters

Abstract: This article has demonstrated the feasibility of a three phase active filter based on a half-bridge topology. Design guidelines for the power circuit have been derived and applied to a 5 kVA IGBT laboratory prototype. In the single phase mode, the active filter can reduce the low frequency harmonic content in the AC line to below 1% excluding the harmonics due to switching action of the converter. In the three phase mode, line currents are corrected under balanced and unbalanced conditions. The neutral current is reduced significantly.