Harmonic

Origin of harmonics

Linear load:The relationship between current and voltage is modeled using a linear method, demonstrating proportionality. Some basic linear loads such as: Incandescent lamps, resistors, and capacitors…

Nonlinear load: The current and voltage are inversely proportional, and the current in non-linear loads can change unevenly, causing distortion that is not sinusoidal when the voltage varies. Some basic non-linear loads such as: Arc furnaces, medium-frequency furnaces, inverters for AC and DC motors, and Uninterruptible Power Supply (UPS)…

Degree of influence of harmonics

Technically

Increased in temperature: Motors, transformers, and conductors experience a reduction in their service life.
Reduced decrease: Motors and transformers operateinefficiently due to energy loss, leading to reduced performance.
Voltage distortion:This impacts power quality and the operation of devices.
Noise generation: Increased temperatures can cause noise, affecting the surrounding work environment.
Electrical Issues: Higher temperatures may lead to circuit breaks, equipment failures, and decreased reliability of the electrical system.

Economically

Increased operating costs: Contribute to higher power consumption, leading to elevated electricity costs.
Reduced equipment life:Increased maintenance and replacement costs due to wear and tear on equipment.
Reduced productivity: Equipment failures or downtime caused by harmonics lead to decreased productivity and economic losses.
Increased investment costs: Factories may need to invest in reactive power compensation systems or harmonic filters, resulting in higher initial investment costs.

Solution for handling harmonics

Choke

This method is effective in filtering and reducing the effects of harmonics. It is favored by many factories for its simplicity and cost-effectiveness.

Operating principle: Based on the principle of electromagnetism, it creates impedance for high-frequency components (harmonics) in the current, while allowing low-frequency components (basic frequencies) to pass through more easily. Typically, resistance coils have a resistance value of 3% to 6% to improve power quality.

Passive Filter

This device enhances efficiency in eliminating harmonics while preserving the fundamental signal. Although the design is straightforward, the distribution grid system and passive filters may not always align with the designer’s intentions.

Operating principle: This filter is based on fundamental components such as inductors, capacitors, and resistors. It operates efficiently under specific system conditions while minimizing the negative impact on other components in the power grid.

Active Filter

This technology uses advanced methods to adjust the filter frequency based on system conditions. In addition to filtering, it can amplify the signal, thereby enhancing overall signal quality.

Operating principle: The active filter measures the current, separates the 50 Hz fundamental component from the signal, and analyzes the remaining frequency components. It then injects a compensation current to cancel out each harmonic component. Typically, an active filter can effectively filter up to the 50th harmonic and achieve a post-filtered harmonic distortion of less than 5%.