1. Introduction In recent years, harmonics are considered as one of the most essential problems in the industrial power distribution networks. The problem of harmonics is increasing due to the use of the variable speed drives (VSDs), the uninterruptible power supplies (UPS), and the solid-state devices. Harmonics current distortion may produce negative effects on the power quality of the power networks. The negative effects include malfunctioning of sensitive devices such as protective relays, motors overheating, and transformer overheating. The current total harmonic distortion (THD) can be reduced to the IEEE standards using harmonics filters such as passive harmonic filters or active harmonic filters. Ahmad Hassan AlObaidly and Abdulaziz Abdulla Alshafai Supervisor: Dr. Khaled Ellithy Department of Electrical Engineering, College of Engineering FALL 2008 Objectives To conduct a study on harmonics, harmonics sources, harmonics representation, harmonics effects, and harmonics indices. To conduct a study on harmonics, harmonics sources, harmonics representation, harmonics effects, and harmonics indices. To study the recommended IEEE-519 standards for the current and voltage harmonics distortion. To study the recommended IEEE-519 standards for the current and voltage harmonics distortion. To conduct a study on the types of harmonics filters. To conduct a study on the types of harmonics filters. To conduct a study on passive harmonics filters design. To conduct a study on passive harmonics filters design. To perform the harmonics analysis and harmonics filter design for a typical gas plant power network using EDSA power system analysis software. To perform the harmonics analysis and harmonics filter design for a typical gas plant power network using EDSA power system analysis software. Computer Simulation Results with the Designed Harmonics Filters HR-5343 UPS-A %THD i =7.37% %THD i =2.98% The current total harmonic distortions (7.37% and 2.98%) are within the IEEE-519 standards. Conclusions Harmonics sources, harmonics effects and harmonics representation have been presented. Harmonics sources, harmonics effects and harmonics representation have been presented. An industrial power distribution network of a gas plant was chosen for the study. An industrial power distribution network of a gas plant was chosen for the study. Measurements of the current and voltage harmonics distortions at the Gas Plant were conducted using AEMC power quality analyzer. Measurements of the current and voltage harmonics distortions at the Gas Plant were conducted using AEMC power quality analyzer. The plant power distribution network for harmonics analysis was developed using EDSA power systems analysis software. The plant power distribution network for harmonics analysis was developed using EDSA power systems analysis software. The harmonics filters were designed to eliminate the dominant harmonics orders to reduce the THD of the current and voltage to the allowable limits recommended by the IEEE 519 standards. The harmonics filters were designed to eliminate the dominant harmonics orders to reduce the THD of the current and voltage to the allowable limits recommended by the IEEE 519 standards. The maximum limits of voltage and kVAR of the harmonics filter capacitor have been checked with the ANSI/IEEE 18 standards. The maximum limits of voltage and kVAR of the harmonics filter capacitor have been checked with the ANSI/IEEE 18 standards. Harmonics Indices and IEEE 510 Standards "Harmonics" term in an AC power system is defined as a sinusoidal component of a periodic waveform that has a frequency equal to an integer multiples of the fundamental frequency (50 Hz) of the power network. The Total harmonic distortion (THD) is a measure of the effective value of the harmonic components of a distorted waveform. Maximum harmonic current distortion in percentage of the fundamental V ≤ 69 kV TDD% % 35≤h23≤h≤3517≤h≤2311≤h<17h<11I SC / I L 5.00.30.61.52.04.0<20 8.00.51.02.53.57.020-50 12.00.71.54.04.510.050-100 15.01.02.05.05.512.0100-1000 20.01.42.56.07.015.0>1000 Power Distribution Network Model for Harmonics Analysis of a Train in a Typical Gas Plant Computer Simulation Results without Harmonics Filters HR-5343 UPS-A %THD i = 42.55% %THD i = 41.38% %THD i = 42.55% %THD i = 41.38% The current total harmonic distortions (42.55% and 41.38%) exceed the IEEE-519 standards Harmonics Filter Design A passive harmonic filter is designed to eliminate the 11 th harmonic order for HR- 5343 Passive harmonic filter to eliminate the 5th harmonic order for UPS-A The voltage and kVAR of the harmonics filter capacitor have been checked with limits recommended by ANSI/IEEE 18-1980 standards. Bus Voltage at PCC (KV) Individual harmonic voltage distortion (%) Total Voltage Distortion, THD (%) V < 693.05.0 69 < V < 1611.52.5 V > 1611.01.5 IEEE 519 standard of current harmonicsdistortions IEEE 519 standard of current harmonics distortions IEEE 519 standard of voltage harmonics distortions IEEE 519 standard of voltage harmonics distortions The THD of voltage is given by The THD of current is given by Single-line diagram of power distribution network Including harmonics sources