A summary of the actual state of battery charger harmonics is presented. The effect of harmonic distortion on the distribution system, especially on distribution transformers, is analyzed. A program was developed that allows the consideration of the transformer life consumption as a function of the battery charger characteristics and charging algorithm. The program is considered to be a distribution planning and management tool. The proposed tool can be easily applied to determine the optimum charging time as a function of the existing load, ambient temperature, and time of day. From the study it can be deduced that a direct connect-and-charge scheme can be detrimental to the transformer life, especially under high temperature and large load. Calculations show the existence of a quadratic relationship between the transformer life consumption and the total harmonic distortion (THD) of the battery charger current. Furthermore, the current THD should be limited to 25 30% in order to have a reasonable transformer life expectancy.

Impact of EV battery chargers on the power quality of distribution systems

FUNDAMENTALS OF HARMONIC DISTORTION AND POWER QUALITY INDICES IN ELECTRIC POWER SYSTEMS Introduction Basics of Harmonic Theory Linear and Nonlinear Loads Fourier Series Power Quality Indices under Harmonic Distortion Power Quantities under Nonsinusoidal Situations References HARMONIC SOURCES Introduction The Signature of Harmonic Distortion Traditional Harmonic Sources Future Sources of Harmonics References STANDARDIZATION OF HARMONIC LEVELS Introduction Harmonic Distortion Limits References EFFECTS OF HARMONICS ON DISTRIBUTION SYSTEMS Introduction Thermal Effects on Transformers Miscellaneous Effects on Capacitor Banks Abnormal Operation of Electronic Relays Lighting Devices Telephone Interference Thermal Effects on Rotating Machines Pulsating Torques in Rotating Machines Abnormal Operation of Solid-State Devices Considerations for Cables and Equipment Operating in Harmonic Environments References HARMONICS MEASUREMENTS Introduction Relevant Harmonic Measurement Questions Measurement Procedure Relevant Aspects References HARMONIC FILTERING TECHNIQUES Introduction General Aspects in the Design of Passive Harmonic Filters Single-Tuned Filters Band-Pass Filters Relevant Aspects to Consider in the Design of Passive Filters Methodology for Design of Tuned Harmonic Filters Example 1: Adaptation of a Power Factor Capacitor Bank into a Fifth Harmonic Filter Example 2: Digital Simulation of Single-Tuned Harmonic Filters Example 3: High-Pass Filter at Generator Terminals Used to Control a Resonant Condition Example 4: Comparison between Several Harmonic Mitigating Schemes Using University of Texas at Austin HASIP Program References OTHER METHODS TO DECREASE HARMONIC DISTORTION LIMITS Introduction Network Topology Reconfiguration Increase of Supply Mode Stiffness Harmonic Cancellation through Use of Multipulse Converters Series Reactors as Harmonic Attenuator Elements Phase Balancing Reference HARMONIC ANALYSES Introduction Power Frequency vs. Harmonic Current Propagation Harmonic Source Representation Harmonic Propagation Facts Flux of Harmonic Currents Interrelation between AC System and Load Parameters Analysis Methods Examples of Harmonic Analysis References FUNDAMENTALS OF POWER LOSSES IN HARMONIC ENVIRONMENTS Introduction Meaning of Harmonic-Related Losses Relevant Aspects of Losses in Power Apparatus and Distribution Systems Harmonic Losses in Equipment Example of Determination of K Factor Rotating Machines References INDEX

Harmonics and Power Systems

A wavelet transform approach using a Morlet basis function is proposed to supervise power system disturbances in this paper. With the time-frequency localization characteristics embedded in wavelets, the time and frequency information of a waveform can be presented as a visualized scheme. Different from the fast Fourier transform, the wavelet transform approach is more efficient in monitoring various disturbances as time varies. The method has been tested on the detection of various simulated disturbances including voltage sag, voltage swell, momentary interruption and oscillatory transients and on the harmonic analysis of the arc furnace from the field test data. Testing results demonstrated the practicality and advantages of the proposed method for the applications.

Application of Morlet wavelets to supervise power system disturbances

Harmonics estimation in emerging power system: Key issues and challenges

A simple fuzzy logic based robust active power filter for harmonics minimization under random load variation

The authors summarize the state of knowledge of the effects of power system harmonics on equipment. The general mechanisms presented are thermal overloading, disruption, and dielectric stressing. Quantitative effects are presented or referenced whenever possible. However, many of the effects are can only be qualitatively described. The types of equipment considered are adjustable speed drives, capacitors, circuit breakers, fuses, conductors, electronic equipment, lighting, metering, protective relays, rotating machines, telephones, and transformers. >

A.E. Emannuel

Papers

Effects of harmonics on equipment