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The paper presents a few issues generated in low voltage distribution grids at the end user's level, by power system harmonics. The introductory section presents shortly harmonics sources, their analysis, effects and measurement methods, appealing mainly to the limits depicted in the specific standards. The following section presents two case studies of power electronics equipment drawing high distorted...
Harmonic emission assessment for Grid Code compliance of Renewable Power Plants (RPP) has to be fair and pragmatic. The CIGRE C4.109 method lacks the ability to determine which harmonic currents have a positive or negative impact on emission in the network. The aggregation of harmonic phasors can support the better understanding of emission based on analysis of the prevailing angle in the harmonic...
In recent years, the use of LED street lights instead of sodium and mercury vapor lights is increased in the distribution networks. The high efficiency and reliability, long life, non-emission of infrared and ultraviolet beams, functioning at very low AC and DC voltage, low heat generation, the application at temperatures from +85 to −40 degrees, are the advantages of these lights. The power electronic...
In this paper, a new method based on quadrature amplitude modulation, which is developed to analyze harmonic spectrum of the voltage and current signals distorted due to nonlinear loads in the power system, is presented. The proposed method aims to reduce the spectral leakage, which occurs in case of oscillations of the fundamental frequency in the Fourier-analysis-based methods. Another aim of the...
This article discusses an improved method for harmonic estimation when Asynchronous Sampling Condition (ASC) is present. The method is based on previous work on a modified DFT (Discrete Fourier Transform) using a compensation of the number of samples. This paper presents the analytical derivation of a new mathematical expression using trapezoidal integration rule and compares the performance of both...
Accuracy requirements at harmonics are defined for electronic current transformers in IEC 60044-8 standard. As indicated there defined limiting values of current error ensure that the contribution of harmonics measurement error would add roughly 15%, in the worst case, on the theoretical error of the corresponding power metering class accuracy. In accordance with IEC 61000-3-12 standard total harmonic...
This paper addresses the issue of power quality management in smart grids. Present development of smart grid technologies such as smart metering are continuously generating novel opportunities and breakthroughs for improving the distribution system performance. This paper proposes a novel approach to be implemented in the new generation of smart meters. This alternative method for harmonics and voltage...
PLN, State-owned Electricity Company in Indonesia has been promoting energy saving lamps (ESLs) through demand-side management (DSM) program since 2005. As a result, those lamps are widely used in Indonesia. To avoid outages on the customers, a brownout strategy (voltage reduction) is sometimes used. The lamps are in this case operated at a lower voltage than their rating. The paper aims to investigate...
This paper presents a study of the deforming regime generated by different light sources. We use several kinds of light bulbs: incandescent, gas discharge lamp and light-emitting diodes. For the acquisition and the analysis of voltage and current signals we use reconfigurable CompactRIO system from National Instruments. It allows real time monitoring of both voltage/current signals and deforming regime...
The article touches the topic of processing the measurements of high frequency harmonics in power grids (above 2 kHz). Measurements in wider band do produce large volumes of data. But often not all of these need to be stored in their raw form for further analysis. This article discusses some adaptable possibilities of reducing the amount of data and proposes an intelligent magnitude-oriented scheme...
This paper provides a new methodology for setting harmonic limits in power systems. This approach is designed to replace the existing harmonic limits detailed in IEC 61000.3.6 and IEEE 519. The methodology provides for replacing the ∼40 or more individual harmonic with three new limits. The new limits are low frequency weighed VTHD, high frequency weighed VTHD and the even harmonic components of V...
The fast Fourier transform (FFT) is the most commonly used technique in power systems signals analysis. However, it is known that if the signal is not synchronized or in the presence of interharmonics, the spectral leakage may occur. To overcome this issue, several techniques are found in literature. The present paper will show a comparison between results of calculating the IEC 61000-4-7 harmonics...
Voltage and current distortion, in most countries, are presently limited by national standards which adopt or adapt the compatibility levels and emission limits of the IEC 61000 series of standards, or the proposed values of the IEEE 519 standard. This paper presents a review of international limits for public networks. Shortcomings of these standards are pointed out and some propositions for improvements...
This paper presents a numerical analysis to determine the minimum sampling frequency for which a linear interpolation of AC Power signals can be reliably used in the digital domain, regarding the harmonics influence for Power Quality (PQ) assessment. The proposed approach of this paper is based on exhaustive simulations which take into account a large combination of distinct values for module and...
Harmonic standards give limits for individual harmonics and for voltage THD. Guidelines are given for the allocation of individual harmonic current but no allowance is made for the control of THD in IEC standards. The paper shows how voltage THD can be controlled within its limit by means of the authors' previously proposed Voltage droop approach. Two main concepts are required to develop an allocation...
In this paper, a new method based on synthetic resampling, which is proposed to analyze harmonics and interharmonics of the currents and voltages generated by nonlinear loads in the power system, is described. The proposed method aims to reduce the leakege effects encountered by the Fourier Transform based methods. Once the true fundamental frequency is determined, the signal is resampled synthetically...
This paper quantifies the harmonic emissions from plug-in hybrid electric vehicles and battery electric vehicles considering indoor level 1 and outdoor level 2 charging. Harmonic distortion trends along the charging period and the harmonic groups and inter-harmonic groups for three electric vehicles (plug-in hybrid sedan, battery electric hatchback and electric pick-up truck) are assessed from harmonic...
The International Electrotechnical Committee Technical Report IEC 61000-3-15:2011 provides electromagnetic compatibility requirements and test conditions for distributed generators up to 75 A per phase. In the current research, two commercially available photovoltaic (PV) inverters up to the capacity of 3600 W were tested following the guidelines proposed in IEC 61000-3-15 in relation to low order...
This paper studies and evaluates the effect of current transformer (CT) distortion parameters on its performance using various secondary current calculation methods according to IEC 44–1 & 44–6 like: magnitude (ratio) error, peak instantaneous error, phase error and composite error. These parameters include: multiple short circuit level (Isc/IR), secondary burden value & type, DC component...
The desire to decrease electrical loading by using energy efficient lighting has resulted in a high level of attention to replacing conventional incandescent lamps with compact fluorescent lamps (CFL). In Iran from energy management point of view, people are encouraged by ministry of power to use CFLs. Also after elimination of subsidies, the substantial increase in electric energy price resulted...
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