What are the most effective ways to mitigate power system harmonics?

IEEE 399 - Brown Book says Harmonics are voltages and currents in electrical system with frequency multiple of fundamental frequency (50Hz). These harmonics bring distortion of sine waves of current and voltage of power system. The non linear loads are main cause of increase of effect of harmonics. IEEE 519 recommend requirement of harmonics control in electrical system to define limit of current and voltage distortion at point of common coupling (interconnection) in power system to avoid malfunction of protection devices. For performance analysis of power system, it is advised to have integrated study of load flow, power factor compensation (capacitor bank) and harmonic performance limits to select proper filters. MAK

Passive filters are indeed a cost-effective solution for mitigating harmonics in power systems with consistent load profiles. However, it's important to note that their effectiveness is highly dependent on the accuracy of the initial design to match the specific harmonic frequencies of concern. Additionally, since passive filters can introduce resonance under certain conditions, careful analysis of the system's impedance profile is necessary to avoid exacerbating power quality issues. For dynamic systems, a combination of passive and active filtering might be more appropriate.

Different strategies are employed to mitigate harmonics in electrical systems, including passive, active, and hybrid filters. Passive filters: Use components such as inductors and capacitors to attenuate harmonics at specific frequencies. Active filters: Use controlled electronic devices to generate currents that cancel unwanted harmonics. Hybrid filters: Combine passive and active elements to take advantage of the strengths of both technologies, offering greater flexibility and efficiency in mitigating harmonics in an electrical system. The choice of the type of filter to use depends on the specific application and the system requirements.

To effectively mitigate power system harmonics, consider employing passive filters, such as harmonic filters and reactors, to absorb or block harmonic currents. Active filters use electronic circuits to compensate for harmonics dynamically. Proper system design, with balanced loads and well-sized transformers, can also minimize harmonics. Regular maintenance, monitoring, and periodic power quality assessments help identify issues early. Educating personnel on harmonic issues and adhering to IEEE standards further contribute to efficient harmonic mitigation in power systems.

Before discussing power stability, we must first understand the entire power system. In general, there are two types of power: active and reactive. While reactive power plays a crucial role, its presence beyond acceptable levels can be detrimental to the system's health. Our primary concern lies in ensuring power reliability, which is essential for both safety and socio-economic well-being within the energy sector. Furthermore, excessive active and reactive power can create power harmonics and system congestion, ultimately leading to degraded insulation in the critical components of the power system—transmission lines, distribution networks, and generation stations.

First, we must under stand that linear load that follow ohm's law doesn't required active filter. However, the in case of non linear load, current wave doesn't resemble voltage wave like in the case of power convertors, VFD, cyclo-convertors, cranes, elevators, UPS, battery chargers, invertors, fluorescent lights, arc furnaces, and welding machines. When harmonics comes in picture, it distorting and changing magnitude of waveforms at 50 Hz. That's why eddy current and I2R losses increase in transformers and generators. Also, it is responsible for overloading neutral of three phase power system, resulting in false reading on sensors. This creates problems of more heating due to both iron and copper losses in Motor and Generators. MAK

Active filters are a sophisticated solution for harmonic mitigation, leveraging real-time adjustments to tackle varying harmonic profiles, which is especially crucial in modern power systems with fluctuating loads and renewable energy sources. Their ability to directly target and cancel out specific harmonics makes them invaluable in maintaining power quality and protecting sensitive equipment in industrial settings. Despite the higher initial costs, the long-term benefits of improved efficiency and reduced power quality issues often justify the investment in active filters.

Empregue filtros ativos que monitorem continuamente as condições do sistema e gerem sinais de compensação para neutralizar os harmônicos. Esses filtros são altamente adaptáveis e eficazes em condições dinâmicas.

Active filters would be the optimum solution for cases where harmonics orders and levels varies based on load type and demand. They detect the harmonics order and level and inject the required current to compensate. Active filters are strongly recommended where power electronics used (mainly drives) such as cables industries, oil and gas, alkaline ....

Hybrid filters represent a sophisticated solution in harmonic mitigation, blending the robustness of passive filters with the adaptability of active filters. They are particularly effective in systems with non-linear loads where the harmonic profile does not fluctuate wildly. By combining both technologies, hybrid filters can dynamically adapt to varying power system conditions, providing a tailored response to harmonic distortion and improving overall power quality. This adaptability makes them a cost-effective and reliable choice for industrial applications.

Please remember that resonance frequency decreases as the capacitor bank size of power factor correction increases. Thus, the harmonics will be dominating in the power system as the impedance is decreased. To reduce harmonics, add Passive Filter (1. Shunt or Single Tuned Filter; 2. Broadband Filter). This provides low impendence path for harmonics. Also, you can increase Pulse Numbers in the convertor circuit to reduce harmonics and also, phase shifting by phase shift transformer will reduce it. Active filters can instantly adapts to changing source as well as load conditions. Thus, harmonics are suppressed but it is more costly affair. We must suppress harmonics to remove voltage stress and dielectric failure. MAK

Power factor correction not only optimizes the use of electrical power but also reduces the thermal burden on electrical infrastructure. By minimizing the phase difference between voltage and current, power factor correction can significantly lower the overall demand on the power grid, leading to cost savings for both utilities and consumers. Moreover, the use of capacitors, inductors, and modern active filters in power factor correction contributes to a cleaner power supply by mitigating harmonic distortions, which can otherwise lead to inefficiencies and potential damage to sensitive electronic equipment.

It can be reduced by using compensators like unified power flow controllers or static synchronous compensators or static synchronous series compensators.

Load management is often the simplest and cost effective way to reduce harmonics. It may require some more playing around from the engineers end to figure out how to distribute the loads and sequence them to reduce harmonics but there are no additional cost of equipment (such as buying filter components) or complexity of design. It may also introduce an element of care to the client, which is a negative, as they may need to follow a certain startup schedule or maintenance.

Load management not only optimizes energy use but also plays a crucial role in mitigating harmonics, which are often overlooked. By strategically adjusting load operations and incorporating smart technologies, we can significantly reduce harmonic distortions. This proactive approach not only improves power quality but also extends the lifespan of electrical equipment by reducing stress from non-linear loads. Educating consumers about efficient practices is equally important for a widespread impact.

One important thing to consider for the importance of harmonics eliminating: -Avoiding/reducing downtime. -Avoiding equipment failures and increasing its lifetime, depending on the application and power system. Many other benefits out of implementing the said solutions and mainly will lead to cost saving plus higher power quality.

Harmonic distortion can significantly impact power system efficiency and the lifespan of equipment. Passive filters are cost-effective for fixed loads, but active filters offer dynamic response to varying harmonic levels. Hybrid filters combine both advantages. Power factor correction not only mitigates harmonics but also improves overall system efficiency. Load management is crucial; by scheduling high harmonic-producing equipment during off-peak hours, the impact on the system can be minimized. It's important to consider a comprehensive approach that includes analysis, design, and continuous monitoring to effectively mitigate harmonics.

Proporcione educação e treinamento para a equipe de operação e manutenção sobre as práticas adequadas de controle de harmônicos. Isso ajuda na identificação precoce de problemas e na implementação de soluções eficazes.