Power System Analysis

Harmonic Analysis of a Given Power System

Power Generation and Transmission Lab

University of Engineering and Technology, Lahore

KSK Campus

Single Line Diagram

In the above circuit harmonics are produced due to charger3, hence voltage spectrum is observed by using bus4 and current spectrum by using dc cable.

Harmonic

Harmonic voltages and currents in an electric power system are a result of non-linear electric loads. Harmonic frequencies in the power grid are a frequent cause of power quality problems. Harmonics in power systems result in increased heating in the equipment and conductors, misfiring in variable speed drives, and torque pulsations in motors. Reduction of harmonics is considered desirable.

1. Even Harmonics:

The even multiples of fundamental frequency are called as even harmonics. E.g. if 50Hz is fundamental frequency than 100Hz, 200Hz etc. will be even harmonics.

2- Odd Harmonics:

The even multiples of fundamental frequency are called as even harmonics. E.g. if 50 Hz is fundamental frequency than 100Hz, 200Hz etc. will be even harmonics.

3- Triple Harmonics:

The triple harmonics are defined as the odd multiples of the 3rd harmonic (ex. 3rd, 9th, 15th, 21st etc.). Triple harmonics are of particular concern because they are zero sequence harmonics, unlike the fundamental, which is positive sequence. The consequence of this fact is that the magnitude of these currents on the 3 phases are additive in the neutral. This can lead to very large currents circulating in the neutral, and unless the neutral is sufficiently oversized this can present a fire hazard. These currents can also circulate in the transformer causing significant overheating there too. Single-phase power supplies for equipment such as electronic ballasts and PCs are the most significant source of Triple harmonics.

4- IHP- Individual Harmonic Distortion:

Individual Harmonic...