Ana Maria Blanco

Effects of high penetration of CFLS and LEDS on the distribution networks

This paper shows the results of a computer simulation of two distribution feeders that supplies energy to costumers who use Compact Fluorescent Lamps and High-Power Light Emitting Diodes. An IEEE 13 node test feeder and a real distribution circuit have been used for the simulations. Voltage and current distortion is analyzed.

Future work on harmonics - some expert opinions Part II - supraharmonics, standards and measurements

A workshop on power system harmonics was organized in Stockholm in January 2014. On the agenda was among others a discussion on what are the main issues on harmonics at the moment and in the near future. Some of the issues discussed at that workshop are presented in this paper and its companion paper. In this paper the following issues will be addressed: the appearance of emission at higher frequencies (supraharmonics); the need for new and improved standards; measurement issues and data analysis.

Power quality disturbances caused by modern lighting equipment (CFL and LED)

The number of compact fluorescent lamps (CFL) and lamps based on Light Emitting Diodes (LED) increases continuously. Compared to the classical incandescent lamps the modern illumination equipment represents non-linear loads that may have impact on the Power Quality in low voltage grids. The network disturbances can be divided in two classes: continuous and transient disturbances. The paper presents the results of an analysis of three disturbance phenomena, namely low order harmonics, higher frequency emission and switch-on currents. Measurement results are presented for more than 150 lamps and possible impact on the grid is discussed with focus on the availability of respective standards. A large part of the analyzed data is organized in a Web-database (PANDA), which was recently developed by the authors as a platform for exchanging harmonic measurements of electronic equipment between laboratories all over the world.

Future work on harmonics - some expert opinions Part I - wind and solar power

A workshop on power system harmonics was organized in Stockholm in January 2014. On the agenda was among others a discussion on what are the main issues on harmonics at the moment and in the near future. The results of this discussion are summarized in this paper and some of the issues are discussed in more detail in this paper and in its companion paper. This paper discusses emission from wind and solar power as well as advantages and disadvantages of active and passive filters.

Cancellation of harmonics between groups of modern compact fluorescent lamps

Modern compact fluorescent lamps (CFLs) are reported to have very high levels of current total harmonic distortion, which may have strong negative impact on the quality of supply in distribution networks. This paper demonstrates how a novel circuit-based modelling approach can be used to investigate and quantify the effect of cancellation of harmonics between the groups of modern CFLs. The presented results are verified by measurements.

Stochastic harmonic load model of residential users based on measurements

Realistic modeling of residential users is important to achieve accurate and reliable results in harmonic studies of public LV grids. This modeling is complex, because multiple factors influence the emission and propagation of harmonics through the network, like time-variation of number and types of connected devices, the supply voltage distortion and the network impedance. This paper discusses the advantages and disadvantages of state of the art modeling methodologies and it describes a novel modeling approach based on measurement of harmonic emission of individual residential users and aggregates of residential users. The developed model can represent the stochastic variation of harmonic currents and is useful e.g. to analyze the impact of new equipment technologies (like EV chargers) on the summation and propagation of harmonic currents in public LV grids.

Implementation of harmonic phase angle measurement for power quality instruments

This paper introduces a general implementation procedure for the measurement of harmonic phase angles using Power Quality (PQ) instruments. It is intended to fill this gap of the standards IEC 61000-4-7 and IEC 61000-4-30, particular with focus on grid measurements. While measurement for a single time instant is well defined, the paper focuses on methods to aggregate the harmonic phase angles in frequency and in time. The application of the methods is illustrated with different simulated and real data. Moreover, the accuracy of the harmonic phase angle measurement and procedures for implementation test are provided.

Design and installation of a smart grid with distributed generation. A pilot case in the Colombian networks

This paper present the design and implementation of a pilot smart grid in the colombian distribution network. This smart grid consists in a low voltage system connected to the existing electricity distribution network, which consider distributed generators and control, supervision and communications systems. These elements allow to provide electric power generation under the scheme of smart grid, which is oriented to promote and to manage the efficient use of the energy, to improve the system reliability and security, to improve the power quality and to increase the system flexibility.

Survey of harmonic current unbalance in public low voltage networks

The paper presents a survey of harmonic current unbalance in public low voltage networks based on measurements of 130 German grids. To ensure a representative set of sites, the selection is based on a classification schema that considers different consumer, generation and network configurations. New individual and aggregated harmonic unbalance indices, which have been recently introduced starting from a harmonic and interharmonic unbalance theory, are applied for the analysis. The results show that fundamental as well as harmonic currents have unbalances higher than 10% and the unbalance levels increase further with the harmonic order. Exceptional high current unbalance levels have been found in some networks with shopping centers and office buildings as unbalance issues have not been taken properly into account at the design stage. The analysis suggests that harmonic studies in public LV networks have to take into account harmonic current unbalances in order to obtain realistic results.

Aggregation characteristic of low-order harmonic currents in residential low-voltage networks

The characteristics of harmonic current emission of residential customers depends significantly on the number of users. While single users have a virtually random behavior, the low order harmonic current of a whole network with several hundreds of residential users usually shows a high level of prevalence with low variation. This paper discusses the aggregation characteristic of low order harmonic currents in residential low-voltage networks based on an extensive measurement database of single users and aggregated users. The first part of the paper compares the harmonic emission of single users and groups of users and shows, how the variation of harmonic magnitudes and phase angles changes with the number of users. The second part presents a systematic simulation of the harmonic currents for groups with stepwise increased number of users. Based on the results, recommendations for the development of probabilistic aggregate harmonic models of residential users are provided.