Harmonic Losses Research Articles

Evaluating the Harmonic Effects on the Thermal Performance of a Power Transformer

Harmonics in the power grid contribute to increased power losses in both the core and windings of power transformers. These losses lead to abnormal rises in temperature causing overheating and reduce the efficiency of the transformer. If the losses and temperature exceed the values set during the design stage for linear load conditions, it can damage the transformer’s insulating materials and shorten its lifespan. To assess the thermal impact of power system harmonics on transformers under steady-state and transient conditions, the rated losses and harmonic losses of the transformer are calculated. These losses are then inputted into a developed thermal 3D finite element method (FEM) performance model to determine the temperature distribution of transformer components. The numerical results from the thermal model will be compared with data from a Hyundai test report and real measurements from Egypt’s Kureimat power plant, specifically a 750 MW combined cycle power plant. The thermal modeling is focused on a step-up (16.5/240 kV), 240 ± 4 × 2.5%, 180/240/300 MVA power transformer operating in ONAN, ONAF1, and ONAF2 modes. This paper shows that the developed model aligns closely with actual measurements and the HYUNDAI test report. The loss calculations reveal that the discrepancy in total losses, with and without accounting for harmonics, becomes more pronounced as the load increases. Using this model, the presence of grid harmonics results in a higher temperature distribution across transformer components, leading to an increase in the hot spot temperature.

Optimal operation of soft open point devices and distribution network reconfiguration in a harmonically polluted distribution network

Soft open point (SOP) and distribution network reconfiguration (DNR) are crucial for modern power systems as they address significant challenges in managing power losses and maintaining power quality. SOP is a power electronic device used in distribution networks (DNs) instead of tie lines. It injects reactive power into feeders and transfers active power between them, while DNR involves altering the network topology to improve DN index. In this paper, the effect of DNR, optimal operation of SOP, and simultaneous operation of DNR and SOP are thoroughly investigated and compared on IEEE 33 bus harmonic polluted DN via particle swarm optimization (PSO). These comparisons were performed by considering three loss-based objectives including fundamental and harmonic losses and summation of them, along with one voltage-based objective function assessing voltage stability, and four Total Harmonic Distortion (THD)-based objective functions quantifying harmonic pollution. Simulation results not only demonstrate the importance of optimal operation of SOP in improving losses and power quality but also highlight the synergistic effect of simultaneous operation of DNR and SOP in further enhancing these two objectives. Results provide valuable insights for future research and practical applications in operation and optimizing power distribution systems.

A Comparative Analysis of European and American Reglementations Used in Power Quality Investigations

Abstract In the realm of electrical engineering, standards play a pivotal role in ensuring the quality and reliability of electrical systems. This paper conducts a comprehensive comparative analysis of the Institute of Electrical and Electronics Engineers (IEEE), International Electrotechnical Commission (IEC), and European Committee for Electrotechnical Standardization (CENELEC) standards, with a particular focus on power quality engineering. Specifically, it focused on key parameters such as the K-factor, the factor K, the Harmonic Loss Factor FHL and the unbalanced factor. By elucidating the differences and similarities between these standards, this study aims to provide insights into their respective impacts on electrical infrastructure, guiding engineering practices, and facilitating global trade. Understanding the regional applicability and industry impact of IEEE, IEC, and CENELEC standards is essential for engineers, manufacturers, and policymakers to navigate the complexities of electrical quality engineering in a diverse and interconnected world.

Measurement and Assessment of Reactive, Unbalanced and Harmonic Line Losses

This study investigates the feasibility of utilizing the line loss power factor to assess the reactive, unbalanced, and harmonic line losses in low-voltage distribution networks and explores the method of calculating decoupled line loss values based on this factor. To achieve this objective, we establish preliminary definitions of single-phase and three-phase reactive, unbalanced, and harmonic line loss power factors, drawing upon the principles of electrical theory outlined in IEEE Standard 1459. These power factors serve as crucial indicators for evaluating the severity of line losses caused by reactive power, unbalance, and harmonic problems. Subsequently, the values of line loss attributed to reactive, unbalanced, and harmonic components are decoupled and quantified using the line loss power factor as a fundamental parameter. The effectiveness and accuracy of the proposed method were verified in Matlab simulation and physical experiments.

Integration of electric vehicle into smart grid: a meta heuristic algorithm for energy management between V2G and G2V

Recently, Electric Vehicles (EV) have been providing fast response and substantial progress in the power generation model. Further, EVs are exploited as adaptable Energy Storage Systems (ESSs) and show a promising performance in ancillary service markets to increase the demand of Smart Grid (SG) integration. The expansion of Vehicle-to-Grid concept has created an extra power source when renewable energy sources are not available. Yet, numerous operational problems still are required to be considered for EV implementation to turn out to be extensive. Even the development of Photo-Voltaic (PV) technology creates a problem in SGs when used for EV charging. Because of this, the Energy Management System (EMS) is required to handle charging requirements and deal with the intermittent generation. Here, in this research, an Improved Honey Badger algorithm (IHBA) is proposed for integrating SGs with EV parking lot, solar panels, and dynamic loads at the Point of Common Coupling (PCC). The proposed IHBA uses a dynamic programming method to optimize the charging Grid-to-Vehicle (G2V) or discharging Vehicle-to-Grid (V2G) profiles of the EVs using the forecasts of PV generation. This algorithm considers user preferences while also lowering reliance on the grid and maximizing SG effectiveness. The study’s findings show that the Honey Badger method is efficient in resolving issues involving large search spaces. The developed method is used to optimize charging and discharging of EV which is tested in MATLAB to obtain a stable load profile. From the evaluation of obtained results, it is evident that the IHBA controller outperforms the WOA and EHO controllers in terms of total harmonic distortion voltage (3.12%), power loss (0.197 kW) and efficiency (98.47%).

Revisited Concept of Three-Phase Transformers’ Short-Circuit Resistances in Light of the Institute of Electric and Electronics Engineers (IEEE) Standard C57.110-2018

Short-circuit resistances are transformer parameters that characterize the electrical load losses and correct operation of these machines. However, the traditional concept of short-circuit resistance, independent of the harmonic frequencies, has been superseded by present transformer standards. Hence, new expressions for short-circuit resistances of three-phase transformers have been developed in this article based on the IEEE Standard C57.110-2018 and are presented jointly with the losses that these resistances characterize. These refer to the secondary effective short-circuit resistance of each phase (Rcc,z), of each harmonic (Rcc,h), and the non-fundamental frequency combined harmonics (Rcc,Hz). Likewise, the harmonic loss factor (HLFz%) has been established to determine the importance of the harmonics in each phase’s load losses. The application of these short-circuit resistances to the calculation of the load losses for a 630 kVA transformer from an actual residential distribution network has shown that the same values are obtained as with the IEEE Standard C57.110-2018, and they are 48.75% higher than those recorded with the traditional short-circuit resistances when the current distortion rates are 36.47%.

Increasing the Energy Efficiency of Traction Electric Drives of Direct Current

Purpose. The work is aimed at improving the energy efficiency of direct current traction electric drives of electric transport by introducing transistor pulse width converters (PWC) with an optimal switching frequency to minimize total electrical losses in the electric drive. The electrical losses of traction electric drives consist of electrical losses in the armature winding and in the PWC transistors. Methodology. To study the dependence on the switching frequency of transistors, the electrical losses in the armature winding and PWC transistors are divided into two parts: static losses from the direct current component of the current and dynamic losses, i.e., losses in the armature winding from harmonic current components and losses in the transistors from transient switching currents. Since the dynamic electrical losses in transistors increase with increasing frequency and decrease in the armature winding, it is necessary to find the optimal PWC co-mutation frequency at which the total dynamic losses in the traction electric drive will be minimal. The goal of increasing energy efficiency in a traction electric drive is achieved by determining the dependence of dynamic electrical losses in the armature winding on the switching frequency of the PWC and computer modeling of the transistor electric drive. Findings. It is found that the relative dynamic electrical losses in the armature winding in the case of polyharmonic power supply are equal to the square of the armature current ripple coefficient. An algorithm for determining the optimal switching frequency of the PWC is developed: 1) the dependence of dynamic electrical losses on the switching frequency of transistors is determined experimentally on computer models of the motor and PWC; 2) the graph of the dependence of total dynamic electrical losses of the transistor electric drive on the time-tothe point of minimum losses, which corresponds to the optimal frequency value, is determined. Originality. For the first time, the authors obtained an analytical expression for the relative dynamic electrical losses in the armature windings, which are equal to the square of the armature current ripple factor. Practical value. Establishing the optimal switching frequency of the PWC according to the developed methodology reduces electrical losses in traction electric drives, i.e., increases their energy efficiency.

Assessment of voltage harmonics' impact on the maximum load capacity of the power supply transformer for the LHCD system.

To study the influence of the voltage total harmonic distortion (THDV) and its spectrum on the harmonic loss factor (FHL) and the maximum allowable load capacity ratio (Imax (pu)) for the transformer of the LHCD system, we use MATLAB software to model the LHCD system and study the winding loss and maximum allowed load capacity of the LHCD system transformer when the supply voltage source is sinusoidal and non-sinusoidal, respectively. The calculation is carried out by the method of IEEE standard C57.110 and the method of considering the skin effect. The calculation results of both methods clearly show that the THDV value of the supply voltage has a significant effect on the harmonic dissipation factor (FHL) and the maximum allowable load capacity ratio (Imax (pu)) of the transformer. And the calculation method considering the skin effect increases the maximum allowable load capacity ratio of the LHCD system transformer by about 2%. The research results have important reference value for the future retrofit design of LHCD system transformers.

Iron loss calculation model of high‐voltage multi‐pole asynchronous motors considering high harmonic flux density

AbstractA variable coefficient segmented iron loss calculation model is proposed for high‐voltage multi‐pole asynchronous motors, which fully considers the influence of high‐order harmonic magnetic density on such motors. This model introduces additional hysteresis loss, improved eddy current loss coefficients, and rotation magnetisation coefficients to account for changes in losses due to small hysteresis loops and skin effect, as well as rotation magnetisation losses. A 710 kW 10‐pole asynchronous motor is used as the research object. A full‐domain iron loss calculation model considering stator and rotor tooth top surface losses is developed. The model can be used to accurately calculate the overall and local harmonic iron losses in the stator and rotor cores of high‐voltage multi‐pole asynchronous motors. And quantitatively analyse the distribution pattern of any harmonic iron loss at any location in the motor core. It realises the refinement calculation and analysis of iron losses in the whole domain of high‐voltage multi‐pole asynchronous motor. Finally, no‐load and load tests were conducted on the 710 kW 10‐pole asynchronous motor. The iron losses of the 710 kW 10‐pole asynchronous motor at no load and load are calculated using the above mentioned model and the classical trinomial constant factor model. The results are compared with the measured iron loss values. It is proved that the iron loss model is more accurate in calculating the iron loss of high‐voltage multi‐pole asynchronous motor. The result helps researchers to calculate the iron loss distribution of high voltage motors more accurately. Thus, the design and operating parameters of the motor can be optimised to improve the efficiency and performance of the motor. It provides the necessary technical support and key basis for the reduction of loss and energy saving of high‐voltage motors and the optimisation of their core structure.

Improvised direct torque control of a permanent magnet synchronous motor

Permanent magnet synchronous motor (PMSM) is widely used in different applications because of their different key operation features. But despite having important key features, PMSM suffers from torque ripple when simple control techniques like direct torque control (DTC) are employed. Several approaches have been raised by many researchers to lessen the ripple when DTC is used for controlling the PMSM drive. In this work, duty ratio-optimized DTC control, which has the same simplicity as conventional DTC (CDTC), and delay compensation for input signal prediction are proposed. In the proposed system, to determine the duty ratio, slope manipulation was made by considering the minimization of torque error and forcing the developed torque to be equal to the reference torque at the end of the span. An online slope determination approach was employed to compute the duty ratio. MATLAB 2021b is used for simulation purposes. The dynamics and steady-state performance of the proposed scheme were tested for both variable-load and variable-speed operations. In addition, the harmonic performance and ratio of harmonic power loss to total active power loss of the motor were evaluated. In general, the proposed scheme performs effectively in reducing steady-state ripple and harmonic.

COMPARATIVE STUDY OF TRADITIONAL PWM INVERTERS AND MULTILEVELS INVERTERS

The need of higher powers in electrical drives has forced the researchers to develop new power source possibilities. Multilevel inverters have been presented as a cost effective solution for various high voltage and high power applications including power quality and motor drive problems. The traditional pulse width modulated (PWM) Inverter does not completely eliminate the unwanted harmonics in the output waveform. Using the multilevel inverter as an alternative to traditional PWM inverters for electric motor drive applications is investigated. The concept of the Optimized Harmonic Elimination Stepped-Waveform (OHESW) technique for a multilevel inverter is presented. The effectiveness of this technique in minimizing the inverter switching losses and its output voltage harmonic content which cause reducing harmonic losses and torque pulsations of an induction motor fed form is investigated analytically. Comparison between the Selective Harmonic Eliminated PWM (SHEPWM) as a traditional PWM technique for three-level inverter and the OHESW technique for multilevel inverter with regard to the switching losses, harmonic distortion, additional harmonic losses in the motor and the pulsating torques is also presented.

Design analysis of intelligent controller to minimize harmonic distortion and power loss of wind energy conversion system (grid connected)

<p>The controlling of internal parametric variations in addition to the non-linearity of a large conversion system of wind energy (WECS) is prime challenges to make the most of the generated energy, with less power loss and secure the proficiency (η) integration conventional grid. An adjustable speed control structure of grid-connected conversion system of wind energy (WECS), with the help of a Permanent Magnet Type Synchronous Generator with intelligent controller minimizes the power loss. The control system incorporates a pair of controllers dedicated to the converters of both the generator and grid edge. The controller at the generator side has the main function is to optimize power that can be withdrawal from the wind by intelligently regulating the turbine’s rotational speed. Meanwhile, the grid edge converter effectively manages active and reactive power by manipulating the d & q-axis current components, respectively. This paper discusses about the improvement in performance of the system when using Neuro-Fuzzy system as compared to Neural Network and Management of energy deliver system via direct control method. The findings reveal that the training time for Artificial Neural Networks (ANNs) is substantial, leading to the Neural Network-Direct Power Contol (NN-DPC) approach being the slowest option among the alternatives. Additionally, the NF-DPC system is less time-consuming than the NN-DPC, with a recorded duration of 24 seconds compared to the NN-DPC’s observation of 8 min and 5 s. However, it is worth noting that the NF-DPC system is somewhat more time-intensive than Common-Direct Power Contol (C-DPC).</p>

Optimal Hybrid Pulse Width Modulation for Three-Phase Inverters in Electric Propulsion Ships

Global interest in environmentally friendly ships has surged as a result of greenhouse gas reduction policies and the demand for carbon neutrality. Despite growing demand for electric propulsion systems, there is a lack of research and development on crucial components. Efficiency and stability are primarily influenced by the performance of inverters, which are essential for driving propulsion motors. Existing inverter control techniques can be of two types: continuous-PWM (pulse width modulation) methods for harmonic performance enhancement and discontinuous-PWM methods for efficiency improvement by reducing losses. However, there are limitations in that each PWM method exhibits substantial variations in inverter performance based on its operating conditions. To address these challenges, this study proposes the hybrid pulse-width-modulation (HPWM) method for optimal inverter operation. By analyzing the inverter’s operating conditions, the proposed HPWM method adopts various pulse-width-modulation (PWM) strategies based on a modulation index to achieve harmonic improvement and loss reduction. Our focus is on comparing and analyzing diverse PWM techniques under varying modulation indices and frequency conditions to attain the optimal operating conditions. Experimental validation of the proposed method was conducted using a 2.2 kW dynamometer. In comparison with existing PWM methods, the proposed method demonstrated superior performance.

Who pays for harmonic network losses caused by PV inverters?

The even growing number of small power (household rate) PV sets and the connecting inverters should warn utility companies to make a reconsideration on the network losses. Of course the main portion of the network losses is in connection with the fundamental current flow along the network. In our former papers [1], [2] and [3] it was pointed out that the harmonic network losses caused by non-linear loads generating harmonic currents actually are paid, because the non-linear loads receive as additional fundamental power the network losses originating by their generated harmonic currents. The PV inverter is a fundamental current power generator, but as a nonlinear element it generates harmonic currents as well. The fundamental current network loss cannot be separated into parts caused by consumption and generation; therefore the utility pays for the total energy supplied by the PV installation including the network loss. And what is the situation regarding the harmonic network loss? The paper gives a theoretical overview of the problem, furthermore – based on laboratory measurements – a proper computer simulation model was developed. Using computer simulations different practical scenarios are discussed.

Monte Carlo Simulation for Assessing the Voltage Level and Losses with Photovoltaic and Electric Vehicle in Low Voltage Network

Livelab from Alliander is a program which started to measure electrical and power quality data in the Dutch distribution network since 2013. This paper presents a methodology to generate the residential load profiles by cumulative distribution function (CDF) based on Livelab measured data, then applying Monte Carlo simulation method, a statistic three phase Load Flow program is developed in order to investigate the voltage level and network losses (harmonic loss is considered) of a typical low voltage (LV) network with the consideration of variable loads and random locations. Then, the prospective impact to voltage level and losses due to the grid connected photovoltaic power generation systems (PV) and electrical vehicles (EV) are discussed, Monte Carlo simulations are done with the different penetration rates of PV and EV, maximum capacity of grid-connected PVs and EVs can be estimated and the possible network losses are calculated.

The impact of feeders in closed-loop arrangement on harmonic distortion and power losses

This paper deals with the power losses and power quality in the medium-voltage distribution network considering feeders in the open- and closed-loop arrangements. The feeders in the open-loop arrangement are changed to the closed-loop arrangement with the aim to improve reliability of the power supply. Apart from that the power quality could be increased, while power losses could be decreased. In the case study the feeders supply loads, while in some cases loads are replaced with the renewable source of energy.

Overview on Permanent Magnet Motor Trends and Developments

The extreme environmental issues and the resulting need to save energy have turned attention to the electrification of energy applications. One of the key components involved in energy efficiency improvements is the appropriate conception and manufacturing of electric machines. This paper overviews the electromagnetic analysis governing the behavior of permanent magnets that enable substantial efficiency gains in recent electric machine developments. Particular emphasis is given to modeling the properties and losses developed in permanent magnets in emerging high speed applications. In addition, the investigation of properties and harmonic losses related to ferromagnetic materials constituting the machine magnetic circuits are equally analyzed and discussed. The experimental validation of the implemented methodologies and developed models with respect to the obtained precision is reported. The introduction of mixed numerical techniques based on the finite element method intended to appropriately represent the different physical phenomena encountered is outlined and discussed. Finally, fast and accurate simulation techniques including aggregated lumped parameter models considering harmonic losses associated with inverter supplies are discussed.

Improved Torque Ripple Suppression Strategy for Brushless Doubly Fed Induction Generator-DC System Considering Winding Harmonic Loss

Improved Torque Ripple Suppression Strategy for Brushless Doubly Fed Induction Generator-DC System Considering Winding Harmonic Loss

Harmonic Loss Reduction of Fractional Slot Concentrated Winding Permanent-Magnet Vernier Motor with Different Stator-Modular Designs

Harmonic Loss Reduction of Fractional Slot Concentrated Winding Permanent-Magnet Vernier Motor with Different Stator-Modular Designs

3D Harmonic Loss: Towards Task-Consistent and Time-Friendly 3D Object Detection on Edge for V2X Orchestration

3D Harmonic Loss: Towards Task-Consistent and Time-Friendly 3D Object Detection on Edge for V2X Orchestration