Harmonic-producing Loads Research Articles

Evaluating Performance and Grid Impacts of On-Grid Rooftop PV System: Case Study of A Mosque

This study presents a load flow analysis of on-grid rooftop PV installed at Masjid Tablighiyah, Bukittinggi, Indonesia. The analysis was conducted using the Newton-Raphson method and simulated using ETAP software. Two scenarios was explored for the analysis: i) connecting the PV into 20 kV bus, and ii) connecting into 380 V bus. Results obtained showed that grid voltage are meeting the utility standards, with all bus voltages are within ±5% threshold. However, certain nodes have moderately low voltages, suggesting a potential need for pre-emptive measures during peak demand. The power factor performance falls within acceptable ranges (84-91%), indicating reasonable system efficiency. However, there is still needed for continuous monitoring to prevent degradation from harmonic-producing loads. In addition, substation transformers and distribution feeders show ample capacity for future expansions as electricity loads grow. The findings provide a robust baseline for additional grid integration studies, emphasizing the need for further enhancements at weaker nodes to ensure sustained stability and reliability in future demand conditions.

Identification of harmonic source location in power distribution network

This paper presents the experimental set-up of identification of harmonic source location in the power distribution network using time-frequency analysis, known as S-transform (ST) at the point of common coupling (PCC). S-transform offers high frequency resolution in analyzing the low frequency component and able to represent signal parameters in time-frequency representation (TFR) such as TFR impedance (ZTFR). The proposed method is based on IEEE Std. 1459-2010, ST, and the significant relationship of spectral impedances components (ZS) that been extracted from the ZTFR, consist of the fundamental impedance (Z1) and harmonic impedance (Zh). This experiment was conducted out on an IEEE 4-bus test feeder with a harmonic producing load in numerous different scenarios. The experimental was tested and verified for three consecutive months. The findings of this study reveal that the proposed method provides 100 percent correct identification of harmonic source location.

Minimization of power losses in passive power filters

THE PURPOSE. Broadband passive filters (BBF) are an effective measure to mitigate harmonic resonance in power systems with nonlinear harmonic producing loads. The disadvantage of simple second-order broadband filters are pure selectivity and excessive fundamental frequency losses. This is especially evident in devices designed for low-order harmonics mitigation. This paper presents new broadband filter configurations with superior performances and low fundamental frequency losses.METHODS. A general method of broadband passive filter design is considered. The filter has the form of single-loaded ladder LC-two-port. Conditions of minimal fundamental frequency loss of the filer are determined.RESULTS. This paper presents new broadband filter configurations with superior damping performances and low fundamental frequency losses. Different broadband filter configurations are compared. The results show that 3-5 order broadband ladder filters have better filtering performance and lower power loss than traditional C-type filters.CONCLUSION. The proposed broadband filters can be used for industrial power systems with powerful nonlinear loads. This will normalize the power quality and at the same time improve the energy efficiency of compensating devices.

Data‐driven robust extended computer‐aided harmonic power flow analysis

The surge in the uptake of harmonic producing loads in 21st-century smart distribution networks has necessitated that robust data-driven approaches for harmonic assessment be developed. Moreover, there exists abundant harmonic data which can be leveraged on for the construction of this harmonic assessment tool. This is the objective of this study. Large volumes of time-stamped data acquired from a practical distribution network in Edmonton, Canada, have been used to construct a time-dependent cross-coupled harmonic model that has been combined with a formulated iterative time-dependent robust extended computer-aided harmonic power flows. The constructed harmonic power flow formulation also considered the constraints relating to the power conservation principle at the fundamental frequency. Practical network conditions including untransposed lines, load unbalance and skin effects of conductors have been thoroughly modelled. The proposed method has been applied to practical radial and weakly meshed medium voltage distribution networks and it demonstrated robustness to initialisation of the iterative procedure. Moreover, findings from this detailed data-driven technique reveal that harmonic impacts in the distribution networks depend on the quantum of harmonic levels, type of network and location of the harmonic sources.

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.

A Diagnostic Analytics of Harmonic Source Signature Recognition by Using Periodogram

<span lang="EN-GB">This paper presents a diagnostic analytics of harmonic source signature recognition of rectifier and inverter-based load in the distribution system with single-point measurement at the point of common coupling by utilizing Periodogram. 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 analysing the harmonic contribution changes. </span><span>Based on voltage and current signature analysis, the distribution of harmonic components can be divided into three zones. To distinguish between the harmonic producing loads, the harmonic components are observed at these zones to get the signature recognition pattern.</span><span lang="EN-GB"> The result demonstrate that periodogram technique accurately diagnose and distinguish the type of harmonic sources in the distribution system.</span>

An Identification of Multiple Harmonic Sources in a Distribution System by Using Spectrogram

The identification of multiple harmonic sources (MHS) is vital to identify the root causes and the mitigation technique for a harmonic disturbance. This paper introduces an identification technique of MHS in a power distribution system by using a time-frequency distribution (TFD) analysis known as a spectrogram. The spectrogram has advantages in term of its accuracy, a less complex algorithm, and use of low memory size compared to previous methods such as probabilistic and harmonic power flow direction. The identification of MHS is based on the significant relationship of spectral impedances, which are the fundamental impedance (Z1) and harmonic impedance (Zh) that estimate the time-frequency representation (TFR). To verify the performance of the proposed method, an IEEE test feeder with several different harmonic producing loads is simulated. It is shown that the suggested method is excellent with 100% correct identification of MHS. The method is accurate, fast and cost-efficient in the identification of MHS in power distribution arrangement.

Harmonic Load Diagnostic Techniques and Methodologies: A Review

<p>This paper will review on the existing techniques and methodologies of harmonic load diagnostic system. The increasingly amount of harmonic producing load used in power system are the main contribution in quantifying each harmonic disturbance effects of the multiple harmonic producing loads and it became very important. Literature proposes two different techniques and methods on the harmonic source identification under the soft computing technique classification. The advantages and disadvantages of harmonic load identification techniques and methods are discussed in this paper. In the proposed method, the issue on the harmonic contribution is determine and transformed to a data correlation analysis. Several techniques to identify the sources of harmonic signals in electric power systems are described and reviewed based on previous paper. Comparative studies of the methods are also done to evaluate the performance of each techniques. However, without sufficient information in this inconsistent environment on the property of the power system, accurate harmonic producing load diagnosis methods are important and further investigations in this regard assumes great implication.</p>

Adaptive Method for Power Quality Improvement through Minimization of Harmonics Using Artificial Intelligence

Power system harmonics are a menace to electric power system with disastrous consequence. Due to the presence of non linear load, power quality of the system gets affected. To overcome this, shunt active power filter have been used near harmonic producing loads or at the point of common coupling to block current harmonics. The shunt active power filter is designed to minimize harmonics in source current and reactive power in the non linear power supplies which are creating harmonics. In this paper, Instantaneous power of p-q theory is employed to generate the reference currents and PI controller is used to control the dc link voltage. In addition to this, Artificial Intelligence (AI) technique is used to minimize the harmonics produced by nonlinear load. The main objective of this paper is to analyze and compare THD of the source current with PI controller and by artificial neural network based back propagation algorithm. The proposed system is designed with MATLAB/SIMULINK environment.

A Comparative Study on Power System Harmonics for Offshore Plants

The field of power system harmonics has been receiving a great deal of attention recently. This is primarily due to the fact that non-linear (or harmonic-producing) loads comprise an ever-increasing portion of what is handled at a typical industrial plant. The incidence rate of harmonic-related problems is low, but awareness of harmonic issues can still help increase offshore power plant system reliability. On the rare occasion that harmonics become a problem, this is either due to the magnitude of harmonics produced or power system resonance. This harmonic study used an electrical configuration for the offloading scenario of a Floating LNG (FLNG) unit, considering power load. This electrical network configuration is visible in the electrical network load flow study part of the project. This study has been carried out to evaluate the performance of an electric power system, focusing on the harmonic efficiency of an electrically driven motor system to ensure offshore plant safety. In addition, the design part of this study analyzed the electric power system of an FLNG unit to improve the safety of operation and maintenance.

An Improved of Multiple Harmonic Sources Identification in Distribution System with Inverter Loads by Using Spectrogram

This paper introduces an improved of multiple harmonic sources identification that been produced by inverter loads in power system using time-frequency distribution (TFD) analysis which is spectrogram. The spectrogram is a very applicable method to represent signals in time-frequency representation (TFR) and the main advantages of spectrogram are the accuracy, speed of the algorithm and use low memory size such that it can be computed rapidly. The identification of multiple harmonic sources is based on the significant relationship of spectral impedances which are the fundamental impedance (Z1) and harmonic impedance (Zh) that extracted from TFR. To verify the accuracy of the proposed method, MATLAB simulations carried out several unique cases with different harmonic producing loads on IEEE 4-bus test feeder cases. It is proven that the proposed method is superior with 100% correct identification of multiple harmonic sources. It is envisioned that the method is very accurate, fast and cost efficient to localize harmonic sources in distribution system.

A Filtering Scheme to Reduce the Penetration of Harmonics into Transmission Systems

The widespread adoption of energy efficient but harmonic-producing loads in residential homes has led to increased injection of harmonic currents into transmission systems. In response to this situation, a novel filtering scheme that can reduce the harmonic penetration into transmission systems is proposed. The scheme utilizes the tertiary winding of a substation transformer to construct a tuned low-impedance path for the harmonic currents. The proposed scheme is capable of trapping two zero-sequence harmonics and three nonzero-sequence harmonics simultaneously. A design procedure has been developed. Performance of the scheme is evaluated and demonstrated through simulation studies. In addition, economic analysis reveals that the scheme is a cost-effective solution in comparison with other applicable methods.

Modelling and Analysis of Controller for Three-Phase Shunt Active Power Filter

Now a days, because of enhancement in high speed computing elements, high voltage controlled semi-conductor devices and emergence of new power circuit topologies, the Voltage Source Converter (VSC) based Active Power Filter (APF) is finding applications for compensating harmonic currents drawn by the various loads. As the active filter consists of semi-conductor devices alone, the response time of this device is very fast and it doesn’t suffer from resonance and other stability problems as faced by the normal passive filters. The Active filters are generally used at harmonic producing loads. Among all APF’s the Shunt Active Power Filter (SAPF) is more prominent at medium/high voltage applications, and also it provides higher efficiency. SAPF in the power circuit can be used either by using the voltage-sourced PWM converter equipped with a DC capacitor or a current-sourced PWM converter equipped with a DC inductor. This paper presents an approach to determine reference compensation currents of the three-phase SAPF under distorted and/or unbalanced source voltages in steady state. It is planned to design a Synchronous Reference Frame (SRF) controller for Voltage Source Converter (VSC) based Shunt active power filter for harmonic compensation. The simulation results have been obtained by using MATLAB/ SIMULINK.

Harmonic current and voltage compensation using HSAPF based on hybrid control approach for synchronous reference frame method

Abstract This paper presents a Hybrid Series Active Power Filter (HSAPF) for compensation of source current and load voltage harmonics. The HSAPF combination consists of a small rated series active power filter and a shunt connected passive power filter. This combination is suitable for compensation of voltage-type as well as current-type harmonic producing load. The HSAPF uses the synchronous rotating reference frame method that based on hybrid control approach, which eliminate both source current as well as load voltage harmonics and also tests the performance of HSAPF for ideal voltage, non-ideal voltage and also at different loading conditions, etc.

Estimating harmonic impact of individual loads using multiple linear regression analysis

SUMMARY This paper investigates the problem of how to quantify the harmonic impact of several known harmonic-producing loads on a particular location of a power network. A multiple linear regression (MLR) analysis-based technique is proposed to solve the problem. This technique overcomes a major limitation of the correlation-based methods: the difficulty of finding valid data sets when the number of suspected loads increases. As a result of addressing this limitation, all measured data can be used for harmonic impact study with the proposed method. The proposed method has been verified through simulation and field case study. Additionally, sensitivity study is carried out to address some practical considerations. The results show that the proposed technique is a reliable tool to quantify the individual harmonic impact of several large harmonic-producing loads. Copyright © 2015 John Wiley & Sons, Ltd.

Inverse S-Transform-Based Identification of Nonlinear Loads in a Power System

In this paper, a modified inverse Stockwell transform has been proposed for the identification of nonlinear loads. The proposed method is based on the maximum values of unfiltered inverse ST and hence is termed as MUNIST. It is a well-known fact that the Stockwell transform technique produces time–frequency representation. As the proposed MUNIST technique is obtained from inverse operation it gives only time-domain representation. Proposed technique produces unique real-time signatures for accurate identification of the bulk nonlinear loads. The information obtained using the proposed technique will be very useful for automatic identification and for subsequent actions for mitigating their effects in the power system. Current measurements of different harmonic producing loads have been used as input for identification. The results obtained using the proposed technique have been compared with the existing techniques to show its efficacy.

Indices for comparative assessment of the harmonic effect of different home appliances

Most of the modern home appliances use power electronic circuits as a power supply to interface with the distribution grid. They have become a major source of harmonic distortions in power distribution systems. This article presents a study of the harmonic current characteristics of such appliance through a measurement-based comparative approach. Magnitude-related indices are introduced to compare the harmonic effects of the various appliances and to quantify their relative severity. Phase angle–related indices are introduced to study the diversity of the current harmonics phase angle among the devices and to understand its effect on harmonic cancellation. The proposed approach can be used to establish a database of harmonic characteristics for home appliances and other small, distributed harmonic-producing loads. Copyright © 2012 John Wiley & Sons, Ltd.

Localization of Nonlinear Loads in Electric Systems Through Harmonic Source Estimation

In a liberalized electric market, the knowledge of the system status is required to deal with management and control issues, such as energy dispatching and protection coordination. In this paper, a procedure for the harmonic source estimation aimed at giving distribution network operators information about the possible presence of harmonic producing loads, along with an indication about the reliability of such information, is studied in detail. The methodology exploits the few real-time measurements existing in distribution systems and all the other available information to provide an initial estimation of the harmonic currents injected by the nonlinear loads. A great attention has been paid to correctly model, in terms of probability distributions, the a-priori knowledge about the harmonic behavior of the loads. This is because the validity of the results strictly depends on the validity of the input data. The practical applicability of the method is discussed with the help of both computer simulations relevant to an IEEE benchmark grid and experimental tests performed on a small low-voltage distribution network in the Measurement Laboratory at the Department of Electrical and Electronic Engineering, University of Cagliari.

Harmonic Source Estimation in Distribution Systems

In power systems, knowledge of system state is required to operate management and control issues, such as energy dispatching and protection coordination. The authors have recently proposed a novel procedure for harmonic source estimation, based on a Bayesian approach, which is aimed at giving distribution network operator information about the possible presence of harmonic producing loads, along with an indication about the reliability of such information. Both measured (the real-time information coming from the field) and a priori information, along with their uncertainty, are used to estimate the forcing terms (i.e., the harmonic currents actually injected by the nonlinear loads) and to evaluate the uncertainty of these estimates. In this paper, significant improvements in the procedure are presented. A Metropolis-Hastings approach is applied to obtain the posterior distributions of each Bayesian estimation process. As a consequence, the harmonic sources are evaluated, along with a full uncertainty description. The methodology is applied to a small distribution network, and the obtained results are properly analyzed.

Determining the Harmonic Impacts of Multiple Harmonic-Producing Loads

Identifying harmonic sources in a given power system is an important task for utility power-quality (PQ) management. This paper presents a new class of harmonic source identification problems: how to quantify the harmonic impact of several known harmonic-producing loads on the harmonic levels observed at a network location. This paper first defines the problem and proposes a harmonic impact index to theorize the problem. This paper then presents a statistical-inference-based method to estimate the index. The data required for this analysis are the harmonic voltage and current magnitudes continuously collected by the existing PQ monitors. The characteristics of the proposed method are investigated through case studies. Finally, additional applications and improvements of the proposed method are discussed.