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In today's complex electrical landscape, the consistent delivery of clean and reliable power is not just an advantage; it's fundamental to operational success. Active Harmonic Filters (AHFs) have distinguished themselves as intelligent solutions, adeptly addressing modern power quality challenges and offering engineers real-time protection they can depend on.

By the conclusion of this guide, you will possess a clear understanding of why specifying AHFs becomes essential when THD (Total Harmonic Distortion) mitigation is mission-critical. This is particularly important for achieving effective power factor correction in your power management strategy and for preserving the integrity of your electrical voltage waveforms.

What Are Harmonics and Why Are They a Problem?

Harmonics are like the extra or unwanted frequencies that combine with the main frequency of an electrical signal. They occur when the current or voltage waveform is not a smooth sine wave.

This harmonic distortion occurs due to the pervasive use of non-linear loads in your electrical systems, such as:

• LED lighting
• Battery chargers
• Industrial rectifiers
• Variable Frequency Drives (VFDs)
• SCR-based temperature controllers
• Uninterruptible Power Supplies (UPS)
• Switched-Mode Power Supplies (SMPS)

During harmonic distortion, you may encounter specific negative impacts, such as:

• Reduced efficiency in power generation, transmission, and utilisation, which consequently increases your operational costs.
• Accelerated ageing of electrical plant components like transformers, motors, and cables due to the additional heating effects of harmonic currents.
• The overloading of Power Factor Correction capacitors (PFC capacitors) and neutral conductors—a particular issue in systems where triplen harmonics can accumulate.
• Spurious operation of protective equipment, including fuses and circuit breakers, thereby compromising your system's overall reliability.
• An increase in the failure rates of electronic devices, which are often highly sensitive to distorted voltage waveforms.

Furthermore, high harmonic distortion impacts your true power factor. Your existing power factor correction capacitors may become ineffective or even be damaged by these harmonics, potentially leading to utility penalties and higher electricity bills, especially if your facility operates under kVAh billing.

How Active Harmonic Filter Works: Principles, Operation, and Key Components

Understanding how AHFs operate involves exploring their core principles, detailed operation, and essential components. Let’s break down these elements to see how they work together for effective harmonic mitigation.

An Introduction to Active Harmonic Filters (AHFs)

Harmonic distortions in electrical systems can cause voltage fluctuations or lead to the overheating of equipment. An Active Harmonic Filter (AHF)—an electronic device—plays a significant role in mitigating such destructive harmonic distortions by detecting and neutralising them as and when they occur.

The Core Working Principle: Detection and Cancellation of Harmonic Distortions

The AHF works based on a highly effective principle—detect and cancel. The device continuously monitors the electrical system in real-time and identifies unwanted harmonic currents generated by non-linear loads. Once detected, it generates equal and opposite (180° phase-shifted) currents that effectively cancel out the unwanted harmonics.

This dynamic cancellation neutralises existing harmonics and adapts to changing load conditions instantly, ensuring consistent power quality. Unlike traditional passive filters that target specific frequencies, AHFs offer broad-spectrum harmonic mitigation with real-time adaptability.

Also Read: What Are Active Harmonic Filters And Its Application?

A Step-by-Step Examination: How an AHF Operates

You need to analyse their dynamic four-stage operational cycle to fully understand how active harmonic filter works and combats pervasive harmonic distortion.

Stage 1: Harmonic Measurement and Sensing

At the heart of every effective AHF solution lies surgical-precision diagnostics. High-fidelity Current Transformers (CTs) are strategically clamped onto your power cables, particularly in three-phase systems, capturing real-time current data at impressive rates, often exceeding 512 samples per cycle. They meticulously track their specific magnitude and phase relationships.

Stage 2: Signal Processing and Compensation Calculation

Once the harmonic signature is captured, the AHF's DSP controller (digital signal processing) instantly transforms into your electrical system's analytical brain.

Advanced signal processing algorithms meticulously cross-reference the measured harmonic data against your facility’s nominal voltage and existing power factors. This enables the precise calculation of the compensation current required to counteract each problematic harmonic component.

This mathematical inversion flips the harmonic phase angles to be exactly 180 degrees out of sync.

Stage 3: Generation of Counteracting Currents

With the blueprint for correction defined, your AHF activates its power electronic stage through industrial-strength hardware. The system has an IGBT or Insulated-Gate Bipolar Transistor-based inverter bridge. This device, which is rated for demanding loads like 480VAC @ 600A, executes sophisticated Pulse Width Modulation (PWM) techniques, such as Space Vector Pulse Width Modulation (SVPWM).

This process rapidly transforms energy from its internal DC bus energy storage into precisely calibrated cancellation currents.

Stage 4: Injection and Continuous Real-Time Adjustment

In this final phase, theory dynamically transforms into protective action through your AHF's closed-loop power amplifier system. High-density injection transformers, or sometimes direct connections, carefully feed the generated corrective current directly into your AC lines.

This action neutralises the disruptive harmonics at their very source of propagation. The system’s rapid refresh cycle, often around 10 kHz, facilitates what electrical engineers term “dynamic impedance adjustment”. This allows the AHF to automatically compensate for constantly varying loads from your diverse equipment, such as VFD motors, SMPS units, or battery chargers.

Key Components of an AHF System

Each AHF has hardware and software components working in perfect synchronisation. Here’s a list of the elements and their functions:

• Current Transformers measure ongoing flow in power lines to identify harmonic signatures for analysis.
• Digital Signal Processor, or DSP, processes signals, calculates harmonic compensation, and delegates control commands. In short, it serves as the system’s brain.
• Power Electronics (IGBT Inverter Bridge) converts DC power into precisely shaped AC counter-currents using advanced PWM techniques.
• DC Bus provides the energy reserve for quick compensation current injection.
  Injection Transformers or Coupling Circuits supply the corrective electricity into the power line at the right point and voltage level.
• Control Interface and Monitoring System enables configuration, remote monitoring, real-time diagnostics, and reporting through user-friendly dashboards.

These components ensure accurate and efficient harmonic compensation for optimal power quality, leading us to explore the key benefits of using AHFs.

Benefits of Using Active Harmonic Filters

The technical advantages of AHFs manifest in measurable operational improvements. These precise filters are effective tools for improving power quality in electrical systems. They work using a closed-loop control mechanism, which allows them to precisely remove unwanted harmonics. Here are the main benefits of AHFs:

• Real-Time Adjustments: AHFs are more efficient than passive filters because they can quickly adapt to changes in the electrical network.
• Enhanced Power Factor: They aid in boosting the power factor, alleviating pressure on the power distribution system, resulting in energy savings and reduced utility costs.
• Decreased Equipment Strain: By removing harmonics and voltage distortions, AHFs prolong the lifespan of sensitive equipment, leading to lower maintenance expenses.
• Financial Benefits: Although the initial investment for AHF is higher, it delivers long-term advantages such as minimised downtime, energy savings, and increased equipment lifespan. Thereby, they are a financially wise choice.
• Regulatory Compliance: AHFs assist facilities in meeting international power quality standards and regulations, ensuring a steady and dependable power supply.

As the demand for cleaner and more reliable electricity continues to rise, the importance of AHFs in maintaining power quality and system stability grows significantly.

Where Are AHFs Typically Applied?

You've seen that AHFs are key to managing harmonic distortion and ensuring superior power quality. These devices are used in commercial and industrial facilities, renewable energy installations, and data centres.

This intelligent harmonic mitigation boosts efficiency, extends equipment life, and safeguards system reliability.

At Nantech Power Systems Pvt. Ltd, one of the leading UPS manufacturers in Chennai, we offer expertly tailored AHF systems combined with our proven UPS technology. Contact our technicians today to explore these solutions and secure your free power consultation!

Harmonic filters, much like superheroes, protect your power systems. They fight against harmful harmonics that can damage the quality of your power supply. There are two main types of these protectors: active harmonic filters and passive harmonic filters. This article offers a detailed comparison between the two, underlining their respective strengths and weaknesses. Grasping this could greatly improve your business by boosting power quality and efficiency. Additionally, you'll learn about the factors to consider when choosing the right filter, with insights from experts like Nantech Power Systems, offering advanced active harmonic filters in Chennai to safeguard your power systems."

Understanding Harmonics and Their Impact on Power Systems

Harmonics in electrical power systems refer to currents or voltages with frequencies that are whole multiples of the fundamental power frequency. For example, if the base frequency is 60 Hz, the second harmonic would be at 120 Hz, and the third at 180 Hz. The electricity supplied to a property may not always be 'clean', and properties can experience harmonics. These harmonics come from non-linear loads, such as electronic devices that draw current in pulses rather than a smooth wave.

This sudden change in current flow injects harmonic currents into your power system, which can cause various power quality issues. These issues can appear as voltage dips and swells, imbalances in voltage or current across electrical phases, and flicker effects caused by repetitive switching of electrical loads. You can notice these problems through signs like flickering lights, overheating transformers, and breakers that trip frequently.

The state of harmonics in your system is represented by Total Harmonic Distortion (THD), a measure of all harmonic effects. It's typically measured up to the 50th multiple of the base frequency of the power system, which is 3kHz or, per some guidelines, the 40th multiple (2.4kHz).

Poor power quality due to harmonics can cause several problems, such as:

• Increased power consumption leading to higher installation and utility bills.
• Overheating of equipment.
• Decreased profitability.
• Potential damage to your equipment.
• Overheating in neutral conductors and distribution transformers.
• Decreased equipment reliability and lifespan.
• Increased maintenance requests and downtime.
• Higher electricity costs.

These additional frequencies distort the AC sine wave in an electrical circuit and can have serious consequences, including reducing the life of your equipment. Now that we've discussed the effects of harmonics on your power systems let's discuss how harmonic filters can help tackle these issues.

Introduction to Harmonic Filters

In understanding harmonic filters, you will explore the basic principles of active and passive harmonic filters. You will gain insight into their unique features and how they function. Let's start this informative journey.

Active Harmonic Filter Basics

Active Harmonic Filters (AHFs) present a modern answer to the issue of harmonic distortions in power systems. They employ cutting-edge technology to detect and study the harmonics in the network. A Central Processing Unit (CPU) then generates a harmonic current that opposes the measured spectrum. It introduces this counteractive current into the system in real time, effectively neutralising all existing harmonics.

We can categorise active filters into three types, each with its unique benefits:

• Shunt active filters: These connect parallel to the load and estimate the harmonic current from the load. They generate a compensating current that neutralises the harmonic component.
• Series active filters: These connect in series to the power system and inject voltage that cancels out the harmonic voltage in the system. This ensures that the load receives a stable voltage.

The primary benefits of active filters lie in their ability to enhance the power factor. They supply both capacitive and inductive reactive power, making them a sophisticated solution for harmonic filtering. Active filters can adapt to changing harmonic influences and filter out multiple harmonic frequencies simultaneously. They employ sophisticated power electronics and control algorithms to dynamically decrease harmonic distortion, injecting compensating currents into the power system. This results in a cleaner, more stable power supply.

Active filters hold several advantages over passive filters:

• They can eradicate multiple harmonics simultaneously.
• They adapt to changes in the power system frequency and the harmonic spectrum.
• They don't create resonance problems in the power system, unlike passive filters.
• They actively generate a reverse compensation current that cancels out various harmonic components, thereby improving power quality parameters such as voltage regulation and unbalance.

AHFs, also known as Active Power Filters (APFs), represent a new breed of power electronic equipment. They employ high-speed DSP devices and modern power electronics technology. They actively suppress harmonics and compensate for reactive power. AHFs are adaptive and can respond to a wide range of harmonic frequencies, making them a versatile solution for various power system configurations. Voltage fluctuations and harmonics can trigger grid disturbances and result in overheating and escalated energy bills. An AHF can mitigate these problems, producing a result better than 5% Total Harmonic Distortion (THD) across the load range, improving the power factor and balancing the load on all three phases if required.

With their adaptive nature and superior technology, Active Harmonic Filters provide an effective solution to the challenges posed by harmonic distortions in power systems. We will now look into the basics of Passive Harmonic Filters and their comparison with Active Harmonic Filters.

Passive Harmonic Filter Basics

Passive Harmonic Filters (PHFs) work on the principles of basic electrical circuit theory. They use resistors, inductors, and capacitors to eliminate unwanted frequencies. These components work together in different ways to create a specific filtering effect.

The success of a PHF in removing harmonics heavily depends on its design and position within the power system. Designing involves choosing the right values of resistance, inductance, and capacitance to create the desired filtering effect. For the best harmonic elimination, you should place the filter near the harmonic source.

A PHF's job is to allow certain frequencies and block others. It accomplishes this by using the unique responses of capacitors and inductors to different frequencies. In power systems, PHFs are designed to 'trap' harmonic frequencies, letting only the base frequency pass. This is achieved by making the filter's impedance high at the harmonic frequencies and low at the base frequency.

There are various types of PHFs, each with its unique response to frequency and circuit setups. These include:

• Single-tuned filters
• Double-tuned filters
• High-pass filters

Although PHFs are relatively simple and cost-effective, they don't offer the flexibility of Active Harmonic Filters (AHFs). Changes in system operation can also affect their performance.

PHFs use passive components like reactors and capacitors, which are tuned to a specific frequency to filter out a particular harmonic part and reduce the resulting harmonics. They also compensate for reactive power, improving the power factor. Let's now compare these to their active counterparts.

Active Harmonic Filter vs Passive: A Scientific Analysis

The world of harmonic filters presents two primary types: active and passive. Each carries unique strengths and weaknesses, and your selection hinges on multiple factors. You need to evaluate their effectiveness in diminishing harmonics, their cost-efficiency, the upkeep they demand, and their flexibility and adaptability under varying power system conditions. Now, let's commence this comparative exploration.

Efficiency Comparison

Several factors can influence the efficiency of both Active Harmonic Filters (AHFs) and Passive Harmonic Filters (PHFs), including the specific harmonic frequencies in the system, the load conditions, and the design and location of the filters. Both AHFs and PHFs play a crucial role in reducing harmonics in power systems, but they function differently and offer varying levels of efficiency. Let's explore how these differences affect their efficiency.

Here are some key differences between AHFs and PHFs:

• AHFs can reduce multiple frequencies simultaneously.
• PHFs typically filter individual harmonics.
• AHFs can actively adjust to changes in the power grid's harmonic current within a certain range.
• PHFs can only reduce the harmonics of fixed orders (3,5,7) within a certain frequency range.

When it comes to safety, AHFs avoid overloading when the active filter limit is reached, unlike PHFs. Moreover, if an AHF becomes incapacitated, it won't affect the motors it optimises power for. This brings us to an important consideration when comparing the two.

Thus, while both AHFs and PHFs play their roles and offer benefits, it's clear that AHFs offer superior efficiency and safety in managing power system distortions.

Cost Comparison

Deciding between Active Harmonic Filters (AHFs) and Passive Harmonic Filters (PHFs) is vital for your business because they come with different cost implications. Let's examine their costs.

At first look, AHFs might seem pricier for a single-drive application. However, their cost-effectiveness grows as the number of non-linear loads increases. This happens because one AHF can correct multiple loads, thus making it a more budget-friendly choice in the long term.

Conversely, PHFs are typically more cost-effective for applications with a large, single, non-linear load. The capital expenditure for one AHF is usually higher than that of a PHF. But, if constant output holds the utmost importance, AHFs are the suggested solution. Despite the higher initial cost, AHFs can significantly reduce energy expenses and ensure consistent output, enhancing your business's net income.

You should consider factors like the specific harmonic frequencies in your system, the load conditions, and the design and placement of the filters when deciding between AHFs and PHFs.

While you must consider the initial investment and future maintenance costs, it's also crucial to take into account the specific needs of your power system when deciding between AHFs and PHFs. Let's shift our focus to the maintenance aspect of these filters.

Maintenance

Both active and passive harmonic filters present unique advantages and disadvantages regarding maintenance. External harmonics can affect Passive Harmonic Filters (PHFs), causing overheating and posing challenges in sizing due to the unpredictability of their impact.

Some modern PHFs, which technicians install on the cold side of wye-connected electrical sub-panels and ground applications, are passive and inductive. These devices do not require any third-party electrical components, eliminating the need for maintenance.

Active Harmonic Filters (AHFs), also known as harmonic correction units (HCUs), offer a more sophisticated solution for managing power system distortions. Unlike passive filters, AHFs can adapt and react to a broad spectrum of harmonic frequencies. This adaptability makes them a flexible solution for various power system configurations.

An active harmonic filter system consists of three main parts:

• A module that detects harmonic
• A control module
• An inverter bridge module

However, maintaining AHFs is not as simple. While AHFs are generally more sophisticated and adaptable than PHFs, their complexity and the incorporation of power electronics might require more frequent maintenance. The specific frequency of this maintenance largely depends on the AHF model and the manufacturer's instructions.

On the other hand, passive filters employ a slower method known as contactor switching. Any changes in the frequency of the passive filters can alter the resonance point, diminishing the harmonic filtering effect.

In terms of operating costs:

• Active harmonic filters might incur higher costs due to the necessity for constant monitoring and maintenance. Regular checks and adjustments are crucial to ensure the filter continues to operate optimally as the conditions of the power system change over time.
• Installing a Passive Harmonic Filter on each drive can be a less intrusive compensation method as it does not require any ongoing maintenance.

After discussing the maintenance aspects, the next consideration is the adaptability and flexibility of these filters.

Flexibility and Adaptability

Active Harmonic Filters (AHFs) and Passive Harmonic Filters (PHFs) both have a role in reducing harmonic distortion in power systems. However, their flexibility and adaptability vary greatly. AHFs use power electronics and control algorithms to dynamically fight against harmonic distortion. They inject opposing currents into your power system, neutralising unwanted harmonics. The result? A cleaner, more stable power supply.

Conversely, Passive Harmonic Filters (PHFs) usually comprise reactive components like inductors, capacitors, and resistors. External harmonics from the mains can influence these components, potentially causing them to overheat. This unpredictable interference of external harmonics can make the task of sizing these passive harmonic filters quite challenging.

Active Harmonic Filters come with the following advantages:

• They can adapt to a broad spectrum of harmonic frequencies, making them a flexible solution for different power system configurations.
• Across the load range, Active Harmonic Filters can bring down Total Harmonic Distortion (THD) to less than 5%.
• If needed, they also have the potential to enhance the power factor and evenly distribute the load across all three phases.

Therefore, given the adaptability of AHFs versus the specificity of PHFs, AHFs offer more flexibility. The choice between the two will hinge on the specific needs of your power system.

Choosing the Right Harmonic Filter: Factors to Consider

The process of selecting the appropriate harmonic filter for your power system isn't a minor task. It demands a comprehensive understanding of the specific requirements of your system and consultation with experts in the field. So, let's begin discovering the ideal harmonic filter for your needs.

Understanding Your Power System

Comprehending the specific requirements of your power system is an essential part of choosing a harmonic filter. This process involves determining the extent of harmonic distortion that needs addressing. For instance, when your power system includes a variety of load types, such as UPS, VFD, and DC drives, active filters often emerge as the best option.

Harmonic filters work by redirecting specific harmonic currents. Interestingly, engineers design some filters specifically to redirect harmonics of certain frequencies.

In this scenario, it's worthwhile to mention the IEEE 519-2022 standard. This guideline aids in designing electrical systems containing linear and nonlinear loads. It describes the voltage and current waveforms across the system, establishes waveform distortion goals for system designers, and explains the connection between sources and loads.

Considering the variety of power systems, understanding the differences between active and passive harmonic filters is crucial:

• Active Harmonic Filters: These filters are mainly used in situations where the harmonic component and size change frequently and the harmonic composition is complex.
• Passive Harmonic Filters: These filters are more appropriate for scenarios where the harmonic components and size remain relatively stable and the harmonic components are less complex.

Consulting Experts

Choosing the correct harmonic filter is essential for your business operations. Professionals from Nantech, the top UPS Dealers in Chennai, can offer helpful advice, providing a wide variety of services, including Active Harmonic Filters.

They offer a variety of power system solutions, such as:

• Online UPS
• Servo Stabilizers
• Isolation Transformers
• Line Interactive UPS
• Power Factor Controllers
• CVT
• Inverters
• Batteries

These top-performance products serve domestic and commercial customers, providing extended maintenance-free service. Their safe and customised solutions can boost your business operations' efficiency. They also plan and set up UPS systems that merge smoothly with your existing power system. So, consider contacting experts from Nantech to assist you in choosing the right harmonic filter for your power system. This choice might be the secret to enhancing your power system's performance.

Wrapping It Up

You've studied the scientific basis of active and passive harmonic filters, understanding their strengths and weaknesses. You've evaluated their efficiency, cost-effectiveness, maintenance needs, and adaptability. It's essential to keep in mind that your power system's specific requirements take precedence when choosing the right filter. For a knowledgeable decision, seek expert guidance or contact Nantech Power Systems. As the saying goes, "Electric power quality is not an Investment but an Expense." Hence, invest wisely in the correct harmonic filter to ensure your power system operates smoothly and efficiently.

FAQs

Is an active harmonic filter better than a line reactor?

Active Harmonic Filters and Line Reactors have roles in managing harmonics in power systems, yet their methods differ. Active Harmonic Filters balance out harmonic distortion by generating currents that counteract it. They can function without Line Reactors, but issues might occur if the filter and the load lack sufficient impedance. In contrast, Line Reactors protect Variable Frequency Drives from power spikes and manage the inrush current flowing into the drive's rectifier. Whether you choose an Active Harmonic Filter or a Line Reactor depends on your power system's unique requirements.

What are the key differences between active and passive harmonic filters?

Active Harmonic Filters and Passive Harmonic Filters both control harmonics, yet their methods differ. Active Harmonic Filters eliminate harmonic components using power electronics. They add active power, matching the harmonic frequency but in the opposite phase, thereby neutralising the harmonic. Conversely, Passive Harmonic Filters employ passive elements such as resistors, capacitors, and inductors. These filters adjust to a particular frequency. Choosing between an Active Harmonic Filter or a Passive Harmonic Filter hinges on your power system's specific requirements.

What are the advantages of using an active harmonic filter instead of a passive filter?

Active Harmonic Filters (AHFs) outperform Passive Harmonic Filters in many ways. AHFs adapt more and perform better. They manage to keep the Total Harmonic Distortion (THD) under 5%, even with a load as low as 10%. In contrast, not every Passive Filter can meet the 8% or 5% THD IEEE-519 specification, even at maximum load. Unlike passive filters, AHFs do not lead to a power factor without load. You can put AHFs anywhere in the lineup, while passive filters require installation at each Variable Frequency Drive (VFD). When handling multiple VFD loads, AHFs are more cost-effective and save more space than passive filters. Want to delve deeper into the advantages of active over passive harmonic filters? Head over to our blog “Why Choose Active Harmonic Filters Over Passive Harmonic Filters?”

How can an active harmonic filter improve power quality?

Active Harmonic Filters, or AHF, enhance power quality by eliminating harmonics. These harmonics can trigger protective devices, interfere with delicate equipment, and distort voltage. AHFs counteract these unwanted harmonics by releasing counteractive currents, purifying and stabilising the power supply. This action not only protects delicate electronic equipment but also improves energy efficiency and minimises the risk of costly downtime. Moreover, AHFs contribute to the power factor of the electrical system. They lessen both thermal and electrical stress on the electrical infrastructure, paving the way for long-term energy efficiency and cost savings.

What maintenance is required for active harmonic filters?

Maintaining Active Harmonic Filters (AHFs) regularly is key to their optimal performance. This involves a few critical steps.

• Inspect the AHF's physical condition regularly to identify any damage, loose parts, or signs of wear and tear.
• Stay alert for software updates from the manufacturer. These updates enhance the AHF's performance and rectify any issues or bugs.
• Verify the AHF's calibration to ensure its accurate reading and response to electrical conditions.
• Monitoring the operational temperature of the AHF is also crucial. Overheating can impair its performance and potentially cause damage.

Following these steps, you can ensure your AHF remains current and accurate, offering dependable power quality management.

How can you quantify the return on investment from installing an active harmonic filter?

An Active Harmonic Filter (AHF) investment can offer several benefits.

• Energy Savings: AHFs boost power quality, which translates to significant energy savings over time.
• Reduced Equipment Downtime: AHFs prevent equipment failure and cut downtime, resulting in cost savings.
• Longer Equipment Lifespan: AHFs extend your equipment's lifespan by reducing the heat and electrical stress from harmonics.
• No Penalties: AHFs help you comply with power quality standards, saving you from utility company fines.

Remember, the exact return on investment will vary based on your unique situation and power system.

What factors should be considered when selecting an active harmonic filter supplier?

When you need to choose a supplier for an Active Harmonic Filter (AHF), remember these key factors:

• Inverter Topology: Many current AHFs build on a 3-level NPC inverter topology. It's a step up from the older 2-level topology and brings numerous benefits.
• Losses: The losses an AHF might have can swing wildly. It hinges on both the design and the topology of the AHF.
• Response Time: Some power quality problems can crop up in a flash. That's why the AHF's response time needs to beat that speed.
• Harmonic Compensation Capacity: How well an AHF can balance a specific harmonic order matters a lot. It can heavily influence the whole system's performance.
• Electromagnetic Compatibility (EMC): A few countries enforce stringent rules about EMC. It's crucial to remember this when you're picking an AHF.

An Introduction to the Active Harmonic Filter

Facing a power quality issue? Get yourself an Active Harmonic Filter and reduce harmonic pollution during electrical installation. Using an active harmonic filter ensures that the current is "clean". An active harmonic filter requires a stable external power source to inject phase opposite current harmonics to downstream loads. Depending on the stability of the connected external power source, its efficiency will vary.

In this blog, we analyze the pros and cons of harmonics. But first, let's see what leads to harmonics in the power system.

What Causes Harmonics in the Power System?

Technically speaking, when the current waveform deviates from the sinewave shape, it is said to contain "harmonics." Is that a good or bad sign? Apparently, harmonics is a bad sign because harmonic frequencies in the power grid cause power quality issues. Why do harmonics occur? Leading inverter battery manufacturers and suppliers from Nantech Power Systems Pvt Ltd, Chennai, point out two things:

Blame 1: Non-linear loads

Power distribution circuits use non-linear devices that create non-linear currents and cause voltage distortions. Some common examples are:

• LED and CFL lighting
• Switch Mode Power Supply (SMPS)
• Computers and PLCs
• UPS and SCR temperature controllers
• Battery chargers and rectifiers
• Frequency drives used with motors

"Harmonic current" is a term commonly used to describe these non-linear currents and voltages. A high load on the power distribution network leads to harmonic currents, which are multiples of the fundamental frequencies.

Blame 2: Electronic switching devices

The excessive use of electronic switching devices in modern equipment has significantly increased the harmonic pollution in the electrical distribution system. Some of the common examples are:

• Unreliable harmonic currents and voltages
• Malfunctioning of electronic equipment
• Neutral conductor and transformer overheating
• Overheating of the rotary machinery
• Capacitor failure

To rectify these power issues, we need one main aspect: Harmonic filters to harmonics coming from the power distribution network. These filters use "frequency conversion technology" to control harmonics and improve power quality in two ways:

• Autonomous detection
• Dynamic filtering of the harmonic currents

Why do We Need Active Harmonic Filters?

With the availability of passive filters, why do experts lean towards active harmonic filters to rectify harmonics in power generation? The reasons are obvious. These filters come equipped with an additional amplifier that changes their action and improves stability. An active filter also:

• Eliminates expensive inductors
• Has high and low input impedances
• Enables efficient interaction with before and after stages
• Remains unaffected by excessive loading
• Pinpoints the harmonic currents
• Establishes anti-currents to minimize harmonics to suitable degrees of intensity
• Enables parameter alterations using inexpensive variable resisters

However, these above-mentioned factors are just the tip of the iceberg. In our next section, we have explained more remarkable advantages in great detail.

Also Read: Why Choose Active Harmonic Filters Over Passive Harmonic Filters?

7 Advantages of Using Active Harmonic Filters

1. Prevent equipment failure and breakdowns.

When many small harmonic-producing devices are collectively causing large amounts of harmonic pollution, filtering the main power supply is a very useful solution. Active harmonic filters effectively prevent failures and breakdowns of devices since they help correct non-linear loads. The filters also provide energy efficiency, which helps extend the durability of the device.

2. Help in maximum use of installed capacity.

An ideal example of active harmonic filters maximizing installation capacity is their use in the AC lines parallel to the loads that produce offending harmonics. The active harmonic filters inject inverted current into the AC lines and cancel harmonics, improving electrical stability.

3. Improve energy efficiency.

One of the best aspects of active harmonic filters is that they are scalable and sized to the harmonic current for multiple loads. You can also install additional units if the total harmonic current exceeds the rating of the single harmonic filter. They also decrease the emission of carbon dioxide.

4. Reliable and provide continuity.

Active Harmonic Filters are handy for areas with significant non-linear loads and many DC drives because they reduce production disruptions. Therefore, these filters also extend the device's life, enabling them to perform consistently well.

5. Curb service and maintenance costs.
Any electrical device that operates at maximum efficiency is bound to work without issues. This theory is applicable for devices with active harmonic filters. Unless the capacitors and resistors are required, the active harmonic filter does not require custom fabrication because it is largely impedance-independent. According to the manufacturers, active harmonic filters can handle wideband harmonic frequencies to minimize service costs.

6. Prevent and reduce energy loss.

Harmonic pollution is synonymous with energy loss because it affects electrical installations' reliability, safety, and efficiency. An active harmonic filter installed on the main power supply can counteract all harmonic currents before reaching the transformer. They also reduce the absorption of reactive power and reduce wear and tear, thereby preventing energy loss.

7. Reduce fire risks.

Harmonic frequencies can increase heating in equipment and conductors. However, with active harmonic filters, you can:

• Choose the parameters
• Set the degree to eliminate pollution levels
• Make timing adjustments
• Monitor and change the settings if necessary

Active harmonic filters are a sure-fire way to reduce fire risks due to overheating.

The Disadvantages of Using Active Harmonic Filters

If you decide to use active harmonic filters, you should also know their shortcomings. Experts say these filters:

• Cause energy losses and VFD tripping due to series impedance
• Do not eliminate relay tripping, downstream failure, and downstream harmonics
• Are limited to upstream grid harmonics
• Malfunction when Total Voltage Harmonic Distortion (THDv) is high and used without a linear load mix
• Are susceptible to failure on voltage fluctuations

The Takeaway

The demand for active harmonic filters is at an all-time high, thanks to the widespread proliferation of non-linear loads. They have become almost indispensable for large power installations, with electric arc furnaces, induction equipment, and electric furnaces. Yes, the active harmonic filter is here to stay!

Want to know more about the active harmonic filter? Visit our webpage right now, or give us a call to know how you can use it to your advantage.

In Chennai, a power supply of an average of 1000MW is given by the power plants. The electricity that comes from these power plants is not clean. The harmonics can cause equipment malfunction or failure because of the voltage fluctuations and distortions in the supply line that can deteriorate the voltage quality. Harmonic Filters reduce risks by reducing harmonic – and you always want to keep the harmonic pollution to under 5%.

One way of reducing harmonic pollution is by using Harmonic Filters. A harmonic filter reduces harmonic pollution and improves Power Quality by dynamic filtering of currents. They are installed for plants and households to improve overall current and voltage outputs. They come in two variants – Active Harmonic Filters (AHF) and Passive Harmonic Filters (PHF).

Passive Harmonic Filters mitigate harmonics by filtering the current wave through an input reactor, output reactor, shunt reactor, and capacitor. They are only limited to individual and stable loads. They are usually limited to their effectiveness and capacity and cannot work with many non-linear loads.

Active Harmonic Filters are used to eliminate or mitigate harmonics from the power received by using a series of transistors and capacitors to clean the current fluctuations. They are larger than Harmonic filters and require more space. They are useful for factories where a constant electricity output is necessary. And they are most effective in maintaining businesses by guaranteeing reduced costs and ongoing outputs.

Also Read: What Are Active Harmonic Filters And Its Application?

Advantages of AHFs over PHFs

In modern-day Chennai, as demand for more output increases, we must consider which filters we use for our plants. And we recommend AHFs over PHFs. Here’s why:

• Active Harmonic Filters provide far more dynamic and superior flexibility in performance as compared to Passive Harmonic Filters.
• Not all PHFs can achieve the IEEE-519 standards (for harmonic pollution, as mentioned above) even at full load. PHFs provide less overall mitigation as load decreases. AHFs can achieve the 5% limit even under 10% load.
• AHFs won't cause a leading PF at no-load conditions. This is important as it helps improve the quality of the current. PHFs, on the other hand, do.
• They can be installed anywhere in the plant line up, and due to their size, even the largest of plants only require 2-3 AHFs. PHFs, on the other hand, need to be installed at every Voltage receiving device. And granted that their sizes are less, a problem is faced when it comes to maintenance.
• They are very cost-effective compared to PHFs, as we only require one unit for the entire assembly. Thus they are more economical for correcting harmonics for multiple voltage receiving devices.
• There is a significant quality improvement over PHFs.
• AHFs won't overload when the load is full.
• If an AHF is rendered incapacitated, the motors used for optimizing power won't be affected. This is because the current itself doesn't run through the filters and runs through a set of parallel channels.
• They are a viable option for long term use.

Since Chennai is now the hub for many businesses, Nantech has the best AHFs to buy in Chennai.
Happy Shopping!

The Active Harmonic filters are also referred to as the PF3 - Intelligent Power Quality Filter. These filters have a growing demand in the market for various applications. The popularity of these filters is due to their ability to lessen the harmonic distortions in the network loads. They can be installed separately or combined with AHF units. The type of filter used in applications is dependent on the harmonics level and issues with operations.

Active Harmonic Filter Installation Principle:

These harmonic filters, when connected in parallel to the mains supply, offer many benefits.
Longer service life and reduced wear and tear due to its capacity to minimize temperature variations. Harmonic filter suppliers provide servicing and maintenance and also fulfill all the obligations of a contract with suppliers of energy regarding consumption.
The power supply is free of interference.

Also Read: Active Harmonic Filters: Pros & Cons Explored

Advantages of Active harmonic filter installation:

The AHF is parallelly connected to the loads and is designed to work with non-linear loads that generate harmonic currents. They can be used in the primary feeder or with separate loads. The AHF has a quick response to changes in load and has an outstanding accuracy of output. The harmonic elimination happens by extracting the current harmonic signal and sensing the load current. The reference is generated by comparing it with the current signal of a load. There is no manual intervention, and everything is dynamic.

Listed below are its advantages:

• Useful in places like hospitals, Airports, shopping malls, etc. where the harmonic loads are generated.
• Meet IEE and other international standards of performance
• Used at the output of UPS to reduce the effect of harmonic signals and increase capacity.
• Can act as a Hybrid filter combining with Acticcomp and Active filter and thus provides a reduction in cost.
• Helps improve the power factor of UPS, rectifiers, etc. in all types of installations.

Apart from the above benefits, there are many advantages for the customers too. Harmonic filter suppliers say that the users of these filters can obtain better reliability of the electric system and there is less loss of power. The generator and transformers also get better distribution of electricity which increases the efficiency and uptime. These filters can be accessed remotely, and the usage is also straightforward. Harmonics filter manufacturer in Chennai calls it a one-stop solution for all harmonics and correction of power factor needs.

Applications of active harmonic filter installation:

An active harmonic filter is used in filtering and compensation of power installations. It is also installed in industrial electronics applications such as UPS systems, data centers and semiconductor production equipment. Photovoltaic systems and wind turbines also use these filters. You can also find harmonic filter installations in many office buildings and shopping centers.

An active harmonic filter is beneficial due to the various advantages that it offers. Due to its high-quality performance and interference-free power, its demand has grown tremendously over the past few years. That has increased the use of it in industries and other applications. Moreover, hybrid power conditioning provides a cost-effective solution for mitigating harmonic signals and compensating power factors.