What are the best methods for reducing power system harmonics on sensitive equipment?

1 Passive filters

Passive filters are composed of resistors, capacitors, and inductors that are tuned to a specific harmonic frequency or a range of frequencies. They are connected in parallel with the harmonic source or the sensitive load, and they act as a low-impedance path for the harmonic currents, diverting them away from the rest of the system. Passive filters are simple, reliable, and cost-effective, but they have some drawbacks, such as resonance, overloading, and sensitivity to system changes.

2 Active filters

Active filters are electronic devices that inject compensating currents into the system to cancel out the harmonic currents. They use sensors, controllers, and inverters to monitor the harmonic distortion and generate the opposite waveform. Active filters are more flexible, adaptable, and efficient than passive filters, but they are also more complex, expensive, and sensitive to power quality issues.

3 Harmonic mitigating transformers

Harmonic mitigating transformers are special types of transformers that are designed to reduce the harmonic distortion in the system. They use different winding configurations, such as zig-zag, phase-shifting, or K-factor, to create phase shifts or cancellation effects among the harmonic currents. Harmonic mitigating transformers are effective, durable, and easy to install, but they are also bulky, heavy, and costly.

4 Harmonic standards and guidelines

Before applying any method for reducing power system harmonics on sensitive equipment, it is essential to follow the relevant standards and guidelines that specify the acceptable levels of harmonic distortion and the best practices for harmonic analysis and mitigation. Some of the most widely used standards and guidelines are IEEE 519, IEC 61000, and EN 50160. These standards and guidelines help to ensure the safety, reliability, and compatibility of the power system and the equipment.

5 Harmonic analysis and measurement

Another important aspect of reducing power system harmonics on sensitive equipment is to conduct a harmonic analysis and measurement of the system and the equipment. This involves using software tools, such as ETAP, SKM, or PSCAD, to model the system and simulate the harmonic effects. It also involves using measurement devices, such as power quality analyzers, oscilloscopes, or spectrum analyzers, to collect data and verify the harmonic levels. Harmonic analysis and measurement help to identify the sources, impacts, and solutions of harmonic distortion.

6 Harmonic mitigation plan

Finally, after understanding the causes and consequences of power system harmonics on sensitive equipment, and following the standards and guidelines, it is necessary to develop a harmonic mitigation plan that suits the specific needs and objectives of the system and the equipment. The harmonic mitigation plan should include the selection, design, installation, and maintenance of the appropriate harmonic reduction methods, such as passive filters, active filters, or harmonic mitigating transformers. The harmonic mitigation plan should also include the evaluation, testing, and monitoring of the harmonic performance and the improvement of the power quality.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?