Harmonic Sources In Power System Research Articles

Aspects Regarding of Passive Filters Sustainability for Non-Linear Single-Phase Consumers

The efficient use of electrical energy (an important component of sustainability) has become increasingly important for electrical consumers (industrial and non-industrial) as we face the challenges of climate change and the need to protect the environment. This theme is essential for guaranteeing a secure and sustainable future for both present and future generations. The power quality and the efficiency of electrical energy are connected to each other. Some power quality problems are caused by natural and unpredictable events, but many disturbances affecting power quality are caused by suppliers and consumers. One of the most important parameters in power engineering is the power factor, which indicates the degree of efficient use of electrical energy. Harmonics is the most important dynamic component of power quality, which affects the operation of electrical equipment and, at the same time, reduces the power factor. Harmonic sources in power systems are generally associated with nonlinear loads. To analyze the operating of passive filters (series L, shunt LC, T type LCL), two groups of experiments (relevant consumers were chosen for the industry as well as from the household sector) were carried out with single-phase nonlinear consumers: in the first group of experiments, a variable-frequency drive is used to supply a three-phase induction motor with variable load; in the second group of experiments, compact fluorescent lamps and LED lamps were used. Following the experiments, it was found that the difficulty of calibrating coils (to size a filter), especially the coils with a core, and the change in electrical properties over time for capacitors. For a certain type of consumer, the improvement of the current waveform depends on the type of filter used, the possibility of improving the power factor (to use electrical energy efficiently), and the role of the source impedance, which is particularly important to improve the efficiency of passive filters. Through the appropriate choice of the passive filter, a decrease in the deforming regime is obtained, with a slight decrease in the active power, and by increasing the power factor, a decrease in the losses of electrical energy from the electrical networks is obtained, with direct implications for the emission of greenhouse gases.

Compensation of Current Transformers’ Nonlinearities by Tensor Linearization

With the proliferation of harmonic sources in power systems, current transformers (CTs), which are the most widely used current transducers in power systems, will have to measure and monitor signals with increasing levels of distortion. The accuracy of the measurement can be affected by the nonlinear response of the CT, which is dependent on the distortion in the measured signal, but nonlinear mathematical models can be used to compensate the measured value. In this paper, the complex ratio of the CT is modeled using a frequency domain model based on tensor linearization, obtaining a real-valued compensation matrix. An accurate measurement setup has been built to characterize the CTs performance in distorted conditions. Experimental results using the proposed compensation technique are presented and discussed for two commercial CTs of accuracy class 0.5 and 1. It is demonstrated that the proposed technique can accurately reconstruct the harmonic components (up to several kilohertz) of the CT primary current from the measured CT distorted secondary current.

Identification of multiple harmonic sources in power system containing inverter‐based distribution generations using empirical mode decomposition

This paper proposes an identification method of multiple harmonic sources in the presence of different inverter-based distributed generations (DG) such as photovoltaic (PV), wind turbine with doubly fed induction generator (DFIG), and microturbine (MT) at the point of common coupling (PCC). To classify the linear loads, non-linear loads (NL) and inverter-based DGs, K-nearest neighbours (KNN) classifier was employed. The features were extracted using empirical mode decomposition (EMD), just from voltage waveforms. To reduce the redundant data, dimension of features vector, and time, the Relief-F method was implemented on the extracted features. Utilising only the voltage waveform for extraction of features increases the speed of the process and decreases the number of measurement equipment. To verify the effectiveness of the proposed method, a number of scenarios such as different harmonic sources with various harmonic orders, load and DG levels were simulated. The results on two test systems showed that the proposed method has a high accuracy even in the presence of different inverter-based DGs. It can be used as an added tool for power-quality engineers and can be integrated into monitor instruments. Also, the speed and precision of this method make it suitable for real-time applications in the power-quality issues.

A verification of periodogram technique for harmonic source diagnostic analytic by using logistic regression

A harmonic source diagnostic analytic is vital to identify the root causes and type of harmonic source in power system. This paper introduces a verification of periodogram technique to diagnose harmonic sources by using logistic regression classifier. A periodogram gives a correct and accurate classification of harmonic signals. Signature recognition pattern is used to distinguish the harmonic sources accurately by obtaining the distribution of harmonic and interharmonic components and the harmonic contribution changes. This is achieved by using the significant signature recognition of harmonic producing load obtained from the harmonic contribution changes. To verify the performance of the propose method, a logistic regression classifier will analyse the result and give the accuracy and positive rate percentage of the propose method. The adequacy of the proposed methodology is tested and verified on distribution system for several rectifier and inverter-based loads.

Localization of Harmonic Sources in Power System - Simulation and Laboratory Study

Localization of Harmonic Sources in Power System - Simulation and Laboratory Study

Identification of Harmonic Sources in Electrical Power Systems using State Estimation with measurement error

In this article we show that the Total Harmonic Distortion (THD) of the current is a reliable index to identify the location of harmonic sources in a power system. It is proved that the harmonic estimators fail to identify harmonic source measurement errors. A 14 node system with two sources of harmonic solved by two methods is tested.

Identification of Multiple Harmonic Sources in Power System Using Optimally Placed Voltage Measurement Devices

This paper presents an effective methodology to identify the multiple harmonic sources along with their harmonic injection levels in a power system using optimally placed harmonic measurement devices (HMDs). Binary particle swarm optimization is used to find the optimal locations of HMDs to collect harmonic data. The proposed harmonic identification approach is based on the direction of harmonic power flow at system nodes to categorize and rank the suspected buses. The method is simple and can be used for locating the multiple harmonic sources in the presence of load modeling errors and measurement errors. The effectiveness of the proposed methodology is tested on 18-bus radial as well as nonradial distribution systems under different scenarios.

An Overview of Harmonic Sources in Power System

Harmonics are multiples of the fundamental frequency of power system. These harmonics are creating distorted voltages and currents in the power system. Distortion of voltages and currents can affect the power quality. This article covers Harmonics sources in power system. Different Sources of harmonics in power system have been discussed.

A wavelet based novel method for the detection of harmonic sources in power systems

Harmonic pollution is one of the most important power quality problems in power system. There is an urgent requirement for the proper identification of the location of the source of harmonic pollution in order that remedial measures can be taken for the improvement of power quality at the consumer premises. This paper presents a new method based on discrete wavelet transform for the identification of prevailing disturbing loads in power systems downstream or upstream from the metering section. It is based on the analysis of detail active power quantities which are based on IEEE Standard 1459-2000 approach. The detail active powers at the lowest level along with the details pollution factor have been used to clearly identify the location of the harmonic source. The simulation results presented here show that the proposed method can effectively indicate the presence of nonlinear load under both sinusoidal and distorted supplies and can also detect the dominant source of harmonic pollution in power system network.

Research on Harmonic Suppression and Power Compensation of Aluminum Electrolytic Rectifier

According to analyze damage of current aluminum electrolytic rectifier, one second order high pass filter was presented, which can complete harmonic suppression and power compensation. At the same time, principle and parameters computation method of it were given in the paper. Experiment results proved, it could reduce harmonic currents and increase power factor effectively if the according methods were used to design filter, it is obvious economic effects and good application prospects in the aluminum electrolytic enterprises. With the current power system harmonic pollution becoming serious, its damage is given great concern by the electrical profession. The aluminum electrolytic rectifier is great harmonic source in power system, which output currents to it, and which bright large sum of extra power rate to enterprises according to current power rate metering method[1].Furthermore, it can reduce rectifier units power factor. Accordingly, it is necessary to complete harmonic suppression and reactive power compensation for power system supplying good quality electrical energy. The given company 160KA aluminum electrolytic rectifier was presented for the experiment object in our country in the paper. According to analyzing its structure and parameters, one design method of second order high pass filter was given, which could complete harmonic suppression and power compensation. After the filter was used, it not only could suppress harmonic current, but also could increase power factor to reasonable level so as to reach anticipation effects.

A New Measurement Method for the Detection of Harmonic Sources in Power Systems Based on the Approach of the IEEE Std. 1459–2000

In this paper, a novel single-point strategy is proposed for the detection of the harmonic sources in power systems. The method is an improvement of a strategy previously proposed by the authors; it is developed from the IEEE Std 1459-2000 approach and it can be entirely implemented in the time domain, thus simplifying the measurement system. The effectiveness of the proposed method is evaluated by introducing simple decision-making rules and by taking the presence of the measurement transducers into account. Several simulations and experimental tests are presented, showing that the enhanced strategy is able to give an useful information on the detection of the dominant harmonic source upstream or downstream the metering section.

Comparison of Nonactive Powers for the Detection of Dominant Harmonic Sources in Power Systems

This paper deals with an innovative technique for the detection of disturbing loads in distorted power systems. The technique is a single-point strategy based on a comparison among different ldquononactiverdquo power quantities already proposed in the literature, which are measured at the same metering section. In this paper, the effectiveness of the strategy is discussed, which also considered the errors of the measurement transducers; the analysis is supported by simulation tests, which were carried out on both a simple single-phase system and an IEEE standard three-phase test power system. The latter was used by other authors as a benchmark system for the analysis of multipoint measurement techniques for harmonic pollution monitoring.

PWM drives: Voltage-type harmonic sources in power systems

PWM inverter induction motor drives with capacitive DC links are becoming more common. Using circuit analysis, physical measurement and numerical simulation, the paper investigates the generation of power-system harmonics by the PWM drive. It is shown that its harmonic characteristics differ from other nonlinear power-system loads and the drive can be more accurately represented as a voltage rather than a current type of harmonic source. This has implications for both analytic harmonic evaluation and practical filter design. In the paper, a modulation function model is developed which can be used to assess the impact of a PWM drive on a power system, when only limited design data are available.

A new method of harmonic power detection based on the instantaneous active power in three-phase circuits

This paper presents a new method of harmonic power detection based on the instantaneous active power in three-phase circuits, and its applications to search for dominant harmonic sources in power systems. The proposed method requires only band elimination filters and a three-phase active power meter to detect the harmonic active power, and it is able to deal with harmonic power flow more easily and precisely than a conventional meter which is based on Fourier series of single-phase circuits. In addition, measurement errors of the harmonic power are discussed theoretically. The validity of the proposed method is demonstrated by digital simulation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An optimal procedure for placing sensors and estimating the locations of harmonic sources in power systems

The problem of where best to take measurements to estimate the locations of harmonic sources in power systems is addressed. Sensitivity analysis and the minimum variance criterion are utilized to solve this problem. The underdetermined case dealing with a few measurements in a large system is analyzed. Three examples are provided to prove that while the optimal sensor placement problem does not necessarily possess a sequential solution, the sequential solution yields a very good approximation solution.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Constrained neural network-based identification of harmonic sources

Constrained neural nets are used to identify the location and magnitude of harmonic sources in power systems with nonlinear loads, in situations where sufficient direct measurement data are not available. This approach permits measurement of harmonics with relatively few permanent harmonic measuring instruments. A simulated power distribution system is used to show that neural nets can be trained to use available measurements to estimate harmonic sources. These estimates are constrained to conform to the available direct harmonic measurements, which improve their accuracy. Suspected harmonic sources can be identified and measured by a process of hypothesis testing.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>