Effect Of Harmonic Currents Research Articles

Theoretical and experimental analysis of electric vehicle motor dynamics under the coupling of harmonic current and temperature excitation

The NVH performance of electric vehicles is crucial for human comfort, and the electric drive system is key to NVH performance. Permanent magnet synchronous motors experience high-temperature increases under high-speed operating conditions, resulting in motor structure deformation at high-temperatures. The radial deformation of the stator alters the airgap dimensions of the motor’s electromagnetic field. The airgap of the motor’s magnetic field has high-sensitivity to these changes aggravating the vibration and noise problems. Harmonic currents in high-speed vehicle motors add to these problems. Therefore, motor dynamics must be studied under the joint influences of airgap distortion and harmonic currents. We proposed a method of modeling permanent magnet synchronous motors under the joint effect of harmonic currents and temperature fields. And established an accurate multi-field coupled vibration response prediction model for permanent magnet synchronous motors. The accuracy of the vibration prediction model was subjected to a bench test. The vibration characteristics of the motor were studied using order and spectrum analyses. We found that the airgap magnetic-field distortion, due to the motor and stator thermal deformation, significantly affected the motor vibration characteristics. The main motor vibration noise was caused by the 24th and 48th order electromagnetic force waves. This provides a reference for establishing an accurate vibration prediction model for permanent magnet synchronous motors.

Synchronization control techniques for shunt active power filter: an overview

The phase synchronization control technique of shunt active power filter (SAPF) is discussed in this article. Due to the harmful effects of harmonic currents on power systems, the issue of decreasing their effects has generated a lot of research. A SAPF is acknowledged as the most dependable instrument in this area. The SAPF will detects the current harmonics present in the power system and also generates and injects the corrective current mitigation in the power system to reduce the current harmonics. This implies that, aside from the capacity to create compensating current, it is more essential to ensure that the SAPF can work in phase with the operational power system so that the compensating current will properly injected. As a result, while constructing SAPF control algorithms, correct synchronisation techniques must be incorporated. In this article, the different types of phase synchronization approach have been discussed such as phase-locked loop (PLL), adaptive linear neuron (Adaline), and unit vector. The results of the study may be used as a guideline and source of information for determining the best method for synchronising SAPF with the associated power system.

Active damping and robust loop shaping control for harmonic minimization

This paper presents an h-infinity robust loop shaping control and LCL filter to mitigate the effects of harmonic currents in the photovoltaic system integrated with the grid. To eliminate the negative effects of the LCL filter, this work applied notch filter active damping. Existing methods for the elimination of harmonic currents were reviewed. Proportional integral control, fuzzy logic control, h-infinity control, and robust loop shaping control are presented. The grid current was analyzed in the system with all controllers applied to control the voltage source inverter of the system to eliminate harmonics in the grid current caused by the inverter and nonlinear loads for two cases, one being constant loading of the linear and nonlinear load and another is the switching of the nonlinear load during the simulation. The results obtained from the proposed method for the two tests conducted were compared with those from other methods to prove the robustness of the proposed technique. The method manages to reduce the total harmonic distortion of the grid current from 7.85% to 0.79% for case 1 and from 11.67% to 1.14% for case 2.

A compound control strategy for LCL-based three phase four leg shunt active power filter

Conventional single inductor filter which is applied to three-phase four-leg shunt active power filter hardly meet the requirements for high frequency harmonic suppression. LCL filter has advantage both in high dynamic response and high frequency harmonic suppression. Repetitive control can realize accurate tracking of multi-harmonics signal. However, the design of corrector for repetitive control is mostly complicated. This paper proposes a topology of three-phase four-leg shunt active power filter based on LCL filter and improve its stability through capacitive current feedback. Compound control strategy which includes PI control and repetitive control is adopted to improve the compensation effect of harmonic current. Corrector for repetitive control has simple structure and is easy to design. The conventional PI control and compound control are compared and analyzed in detail. Moreover, the difference of property between LCL filter and single inductor filter is compared and analyzed. Simulation results show the correctness and effectiveness of the designed LCL filter and the proposed compound control strategy. The proposed method provides a reference for making three-phase four-leg shunt active power filter more practical.

Evaluation of harmonic current effect and distribution line voltage control ability of reactive power control by use of power factor correction converter in consumer load

AbstractIncrease of photovoltaics (PV) penetration and concentration of electric vehicle (EV) charging may cause voltage violation in distribution lines. One measure for voltage violation in distribution lines is reactive power control. In this research, to reduce additional installation cost of reactive power control equipment, reactive power control by use of power factor correction converters in consumer loads was proposed. In this paper, voltage control ability of the proposed method was evaluated from the point of additional increase of PV generation and EV charging. Distribution voltage distortion caused by harmonic currents from consumer loads to which the proposed method were applied was also evaluated from the point of maximum reactive power output from loads within allowable voltage distortion level.

Optimization Design of AC Filters for HVDC Systems Based on Improved Particle Swarm Optimization Algorithm

In order to reduce the adverse effect of harmonic currents on AC systems and ensure the effective transmission of power in high voltage direct current (HVDC) transmission lines, AC filters (ACF) must be installed on AC buses. Aiming at the limitations of current design methods for AC filters in HVDC systems, this paper proposes a new optimization design method using improved particle swarm optimization (PSO), which aims at the cost of filter investment and constrains the total harmonic distortion rate of AC bus voltage and the telephone harmonic form factor. The optimization mathematical model of AC filters is established, then an improved PSO algorithm is proposed to achieve the optimal design of AC filters. This algorithm introduces a mutation operator and the constraint processing mechanism to improve the exploration ability of this algorithm. Lastly, the simulation model of the ±500 kV HVDC system is established, and the simulation results show that the AC filters optimized by improved PSO have the lowest investment cost while satisfying the harmonic restriction standard.

Evaluation of Harmonic Current Effect and Distribution Line Voltage Control Ability of Reactive Power Control by use of Power Factor Correction Converter in Consumer Load

Evaluation of Harmonic Current Effect and Distribution Line Voltage Control Ability of Reactive Power Control by use of Power Factor Correction Converter in Consumer Load

AC Loss Effect of High-Order Harmonic Currents in a Single-Phase 6.5 MVA HTS Traction Transformer

Traction transformer is one of the critical electrical devices in high-speed trains. To increase transformer efficiency up to 99% and reduce weight and fire risks, we are currently building a 6.5 MVA superconducting traction transformer. Assuming 15 as a realistic cooling penalty, thermal loss from the transformer windings cannot exceed 4 kW in order to meet 99% of efficiency. There are non-ignorable high frequency harmonics in the traction side of the transformer, so it is important to investigate the effect of harmonic current on ac loss in transformer windings. We explored the dependency of ac loss in transformer on the amount of the 13th harmonic in traction side, by means of numerical calculation in a 2-D axisymmetric model using the H formulation. Simulations were also carried out to study the influence of the phase state of the 13th harmonic, either in phase or out of phase compared to the fundamental current, and multiple harmonics together in traction winding. Results show that the 13th harmonic must be limited under 1.5% of the rated current to fulfill the aim of 99% efficiency. AC loss in transformer increases when maximum amplitude of distorted currents carrying the same order in-phase harmonic but different amount increases. With various harmonic components in the LV winding, it is important to consider both the maximum current and waveforms to have a clear idea of loss behavior in the transformer.

Application of Resonance Analysis to AC–DC Networks

Medium to long-distance underground ac lines and both short- and long-distance HVdc are frequently integrated into network expansion plans. In conjunction with growing numbers of power-electronic converters in the grid, there is a rising risk related to the effects of harmonic currents. Resonance analysis should therefore be part of power system expansion planning. In this paper, network harmonic modeling and analysis are discussed, in particular, power transformer and power converter frequency models are proposed. Frequency scanning and resonance mode analysis are compared and discussed. The changes in resonance response due to transmission network expansion are drawn. The methods are applied to the investigation of the impact of one link reinforcement, both ac and ac solutions, as well as the impact of the power transformer disconnection. The performed analysis enables finding the resonance location at each studied case. The frequency analysis methods presented in this paper enable forseeing network frequency behavior that is valuable for both network analysis and network expansion planning.

Air-Gap and Yoke Flux Density Optimization for Multiphase Induction Motor Based on Novel Harmonic Current Injection Method

This paper investigates a novel harmonic current injection method to optimize air-gap and yoke flux density distribution for multiphase motor simultaneously. The effect of harmonic currents on air-gap flux density and yoke flux density is analyzed as a whole, while the traditional method focuses on air-gap flux density optimization only. The proposed method fully makes use of multiple control freedoms and the optimal coefficients for corresponding harmonic current are derived. The theoretical analysis and experimental results indicate that novel harmonic current injection method is suitable for heavy load condition. Maintaining the same stator current density, a nine-phase induction motor improves torque density up to 8.47% with the proposed method. A three-phase induction motor is designed to verify the effectiveness of multiphase motor with concentrated full-pitched winding. Furthermore, the torque density and efficiency for two motors are compared under various load condition. Finally, a multiphase variable speed drive system is constructed and the proposed method is validated by experiments.

Impact of different harmonic loads on distribution transformers

The increased usage of electrical load devices causes non-sinusoidal waveforms of currents and voltages in the power system. These harmonic loads have a significant impact on distribution transformers. The primary effect of harmonic currents are the additional power losses in transformer components, which result in increase in generated heat, as well as reduction of transformer’s life-expectancy. This study examines the effects of different nonlinear loads on а dry-type three phase distribution transformer with rated power of 4.5kVA and rated voltage 440/380V. Measurements are done to several relevant parameters, such as: current and voltage high order harmonics, active and reactive power, power factor, total harmonic distortion etc. with sophisticated instruments in laboratory conditions. Using the measurement data, additional power losses are calculated according to the mathematical model proposed in the IEEE Std. C57.110-1998. This study shows an experimental confirmation of theoretically expected results.

Single Tuned Harmonic Shunt Passive Filter Design for Suppressing Dominant Odd Order Harmonics in order to Improve Energy Efficiency

Power quality refers to the provision of the clean and stable electrical power supplies with least interruptions of current and voltage However, power quality problems arise due to the application of nonlinear loads with end user devices. Electrical installations majorly suffer from adverse effects of harmonic currents and voltages. Though, this problem has been decades long and pattern of investigation for the researchers but due to evolution of semiconductor technology, it has become burning issue with reference to the power system loads. Therefore, it becomes necessary to mitigate these harmonics for the safe operation of electrical appliances. Thus, harmonic passive filters are cost effective and easy to implement. In this work, the mitigation of current harmonics has been accomplished through single tuned Shunt Harmonic Passive Filter (SHPF). Furthermore, the application of six pulse multiplication converter technique ensures the mitigation of dominant 3rd harmonic currents and reduction of succeeding 5th and 7th harmonic currents. Furthermore, shunt operation of single tuned harmonic passive filter enables the current to follow the low impedance path. Consequently, the current harmonic distortion becomes less than 5 % according to allowable IEEE 519 -1992 standards. This reduction in harmonic distortion not only reduces the losses incurred in the system but it also improves the energy efficiency of the electrical Power Distribution System (PDS).

Optimization Design on Power Filter of TCR Under Asymmetrical Voltage

For resolving the problem that power filter cannot work normally because TCR (thyristor controlled reactor) generates extra third harmonic current under asymmetrical voltage, the paper proposes the estimation method of current capacity that TCR generates extra third harmonic current under asymmetrical voltage. Considering extra third harmonic current under asymmetrical voltage, Optimum method based on genetic algorithm is used to design the parameters of power filter. With reactive power compensation and harmonic suppression project of a steel mill as example, the proposed method is simulated by Matlab. Simulation results show optimized power filter can eliminate extra third harmonic current effects under asymmetrical voltage, meet the requirement of reactive power compensation, reduce harmonics current that load injects into system, and guarantee the power filter safe operation under asymmetrical voltage.

Considerations on hosting capacity for harmonic distortions on transmission and distribution systems

The increasing penetration of renewable/distributed sources with non-linear characteristics demands a clear methodology for determining the amount of generation which can be connected to the system without deteriorating the performance (the hosting capacity). This paper proposes a methodology for determining the hosting capacity regarding harmonic distortions. The method includes aggregation effects of harmonic currents, the influence of harmonic distortion limits and harmonic generation profile. To exemplify an application of the proposed procedure, a simple case study is performed and analyzed.

Harmonic Current Effect on Three Phase 100kVA Transformer Losses under Static Load and Dynamic Load

This paper describes the harmonic current effect under static and dynamic load on 3 phase 100kVA transformer model. The methodology that used to measure a harmonic current is using power analyzer with different excitation. The experiment is conducted by changing input voltage with different flux density. A waveform can be obtained by using the data collected. 3rdorder of harmonic gives a high impact to the complex waveform. At 0.6 Tesla, 50 Hz, the 3rdorder of harmonic current under static load and dynamic load is 0.00196A and 0.26746A respectively. Therefore, both static and dynamic load were give an effect to harmonic current effect on transformer. This is because when the transformer connected to the load, more current and voltage induced in order to energize the load. Moreover, the loads itself have their own harmonic effect because of the functional mechanism.

Differentiation of Harmonic Current Effect at T-Joint and Corner Joint on Three Phase 100kVA Transformer Losses

This paper describes the harmonic current effect at T-joint and corner joint on 3 phase 100kVA transformer model. The methodology that used to measure a harmonic current is using search coil connected to oscilloscope. The experiment is conducted by changing input voltage with different flux density. From the results obtained, the 3rdorder harmonic current shows the highest for both T – joint and corner joint. The highest harmonic occurred at T – joint. For in plane, the harmonic current is 0.237A at corner joint and 0.389A at T - joint. At normal condition, the harmonic current were 0.250A and 0.769A at corner joint and T – joint respectively. This happened because of more energy required for transferring the flux to the left and right of the core. The corner joint of harmonic is less since the flux direction is 90° thus smaller amount of energy is required for the movement.

Effects of Harmonic Current on Dynamic Behaviors of High Speed Motorized Spindles

Abstract According to the producing mechanism of the harmonic current, the equivalent circuit of harmonic current for the high speed motorized spindle (HSMS) is established. Meanwhile, the formulas of oscillation harmonic torque, fluctuating speed and motor loss are developed on the basis of the superposition principle, which can be used as the foundation for the analysis of the harmonic current effects on the dynamic behaviors of the HSMS. Finally, the harmonic interference test is carried out on a 170MD15Y20 type spindle with different rotational speeds to validate the theoretical model. The results indicate that the motor loss generated by harmonic components can not be ignored. When the speed decreases, the harmonic current effects on the dynamic behaviors of HSMS increases, which indicates that the ripple amplitudes of output torque and speed rise, and the motor efficiency declines, thus the scope of the spindle speed is limited.

Analysis of Harmonic Current in Permanent Magnet Synchronous Motor and Its Effect on Motor Torque

The inverter is used as the power supply of modern permanent magnet synchronous motor (PMSM). The inverter may produce harmonics in inversion process and form harmonic currents in motor stator winding which can lead to factors against motor smooth operation such as torque fluctuating and winding heating. This article focuses on the harmonic currents formed in the motor stator winding by getting the harmonics frequency spectrum with software. The effect of harmonic currents to motor torque is analyzed with the finite element method (FEM).

고조파 전류에 의한 배선용 차단기 동작 특성

Malfunction and nuisance tripping of molded case circuit breaker(MCCB) caused by harmonic currents have been reported. But no data is available on the behavior of MCCB under harmonic currents. This paper tested the effects of harmonic currents on four common types of MCCB(thermal, thermal magnetic, magnetic and electronic types). Results of experiment detected no nuisance tripping with any of the breakers tested under test currents, included harmonic current, below rated currents. Additionally it was found that varying harmonic loading conditions did not affect manufacturer specified trip times for thermal only and thermal magnetic circuit breakers. However, under overloaded conditions, trip times of the magnetic only circuit breakers were gradually slowed according to increasing of harmonic currents, and it could cause hazardous overheating of cables. So, the use of magnetic only circuit breakers in the place harmonic currents we serious must be avoided.

Harmonic current’s coupling effect on the main motion of temper mill set

The paper probes into a probable condition that causes temper mill chatter from aspect of electromechanical coupling of complex electromechanical system, and mainly studies the effect of temper mill electrical driving system harmonic current on the main motion of temper mill set. Aiming at the electrical driving system of CM04 temper mill, the effect of harmonic current is analyzed and evaluated according to different load. Combining the features of CM04 temper mill’s structure and its working state, the paper discusses in every detail how the harmonic current in main circuit, which can be regarded as a disturbance via feedback control circuit, influences main motion of temper mill set.