How to mitigate harmonics in power systems?

Harmonics injected power quality difficulties as technology advanced and with the advent of complex electronics such as electronic lighting, uninterruptible power supply, programmable logic controllers, and variable frequency drives. Harmonics’ influence on the quality of signals produced by this equipment prompted adjustments in design, filtering techniques, and installation procedures.

Harmonics Definition (What are harmonics?)

Harmonics are described in an electrical power system as the multiple of the current or voltage at the fundamental voltage frequency. Harmonics are present whenever a waveform deviates from the typical sinewave shape.

Harmonics Causes

AC signals are classified as linear or nonlinear based on how the systems take power from the supply source. Nonlinear systems that draw current in brief, sudden pulses create harmonics. The drawn pulses cause distortion in the waveforms of the current. The distortion produces harmonics, which cause power issues, impacting both the load and the distribution system. Electronic equipment such as televisions are examples of nonlinear load systems.

Basic Electrical Harmonics

Power is generated here by the generator. It has a frequency known as the fundamental frequency or first harmonic frequency. Its frequency is either 50 or 60 hertz, depending on your country’s preference. All electrical and electronic systems are designed to operate efficiently at this frequency.

Orders of Harmonics and Complex Waveforms

Harmonics of the Second Order

Second-order harmonics are waveforms with frequency of 100 hertz, or 50 hertz multiplied by two. This indicates that the frequency of the second harmonics is double that of the fundamental frequency.

When the fundamental harmonics reach zero, it reaches its maximum value, and so forth. This is why the second harmonic commences the opposite direction, meaning that current flows in the negative sequence in the provided electrical circuit. The induction motor is affected by the negative sequence current because it resists the revolving magnetic field. As a result of the opposition, the motor delivers less mechanical torque than anticipated. The negative sequence is another name for this sort of harmonic.

Harmonics of the Third Order

This has three times the frequency of the fundamental harmonic. The frequency is set to 150 hertz. This is a very hazardous harmonic.

Both the third and basic harmonic currents approach zero simultaneously. They both reach a high value at the same time, but their points are opposite each other. This action causes the harmonics to generate a zero-sequence current, which raises the neutral voltages in the power system. When the neutral voltage is increased, the relay activates a circuit breaker. The third harmonic current is responsible for this phenomenon. The third harmonic is sometimes referred to as triplens.

Harmonics of the Fourth Order

The frequency of this is 200 Hz, which is four times the fundamental frequency.

When the fundamental harmonic current reaches its maximum magnitude, the fourth harmonic follows suit. As a result, such harmonics increase the current flowing through a conductor, raising the temperature of the equipment. Positive harmonic is another name for it.

Fifth-order Harmonics are a kind of harmonic.

Fifth-order harmonics have a frequency of 250 Hz and properties comparable to third-order harmonics, but operate at a higher frequency.

Harmonics Synthesis

  • Harmonics is the variation of the fundamental frequency by two or more multiples.
  • Harmonics increases the amount of heat produced by a system, the amount of voltage currently emitted by an item, and the torques released by motors.
  • Fundamental harmonics have frequencies of 50 or 60 hertz, depending on the nation.
  • Harmonics are defined as the multiple of the fundamental frequency’s current or voltage.
  • Power emanates from the generator and its frequency in fundamental electrical harmonics. basic frequency is the frequency at basic electrical harmonics.
  • Second-order harmonics have frequencies of 100 Hz – or 50 Hz multiplied by the fundamental frequency.
  • The third-order frequency is three times the fundamental frequency, resulting in a frequency of 150 Hz.