- A “linear” load connected to an electrical power system is defined as a load which draws current from the supply that is proportional to the applied voltage. For example: resistive load, incandescent load.
- A load is considered to be “non-linear” if the impedance changes with the load. Due to this change in impedance, the current drawn by non-linear load is also non-sinusoidal in nature, even when it is connected to a sinusoidal voltage source. For example: computers, variable frequency drives, discharge lighting.
- These non-sinusoidal currents contain harmonic components which interact with the impedance of the power distribution system, creating voltage distortion that affects both the distribution system equipment and the load connected to it.
- • Static power converters are the equipment that use semiconductors to convert AC to DC, DC to AC, and AC to AC, and constitute the largest non-linear load connected to the electrical power system.
- These converters are used in various applications in industries such as uninterruptible power supply, variable frequency drives, SMPS, etc. These converters used in a variety of applications draw non-linear current and distort the supply voltage waveform.
- These non-sinusoidal components are divided into two components: fundamental component and harmonic component.
- The higher the harmonic portion of the quantity, the distortion of this quantity, or in other words, the larger the deviation of the quantity from the sinusoidal fundamental frequency.
Harmonic Filters
