Cut costs: Mitigate harmonics for compliance at optimal cost

  • Overview
  • Plan a new build
  • Plan an upgrade
  • Case studies
  • Related products
  • Explore more about harmonic mitigation
  • Contact us
Cost-effective harmonic mitigation

Cost-effective harmonic mitigation

In the power transmission network, many forms of power distortion are present. Harmonic distortion is the most regulated form of distortion, occurring in the frequency range up to 2 kHz. Harmonics can damage equipment, leading to inefficiency and even failure. To reduce risk and optimize operating costs, it’s worth mitigating power distortion. Learn how to mitigate harmonics cost-effectively by planning ahead .

Plan mitigation early

Harmonics compliance: Use mitigation only when needed

Excessive total harmonic distortion in the distribution network costs money. You risk damage to critical equipment, reduced productivity and lower efficiency. Danfoss gives you expert advice on how to reduce this risk, at optimal cost. Using new drive technologies, you can save significantly on sizing and dimensioning of the electrical network, whilst mitigating harmonic content.. Therefore, to optimize the overall electrical system, it’s vital to select the drive (VFD) early in the system design phase. 

How can you curb costs and still comply with power quality regulations?

For transformer load below 40%, and 5% THDv* limit, no mitigation is required.

For non-linear transformer loads of 40% and above, use the most energy efficient technology to achieve < 5% THDv*.

Aim to regulate harmonics only to meet the required standard and according to the installation requirements. Do not over-compensate for harmonic content. Need help in regulating harmonics? You’re welcome to contact us.

*Abbreviations: THDv: total harmonic voltage distortion. THDi: total harmonic current distortion

The most popular regulations (for example, IEEE 519) set THDv requirements, but do not specify total harmonic distortion requirements in terms of THDi. Therefore, design to 5% THDv, to meet regulations. Some regulations require THDi ≤ 5% or even THDi ≤ 8% at drive mains terminals. When these THDi levels are specified, designing to meet them can bring unnecessary cost and additional losses, so contact Danfoss to get the best advice.

Perform a simple analysis. Fewer than 10 minutes of calculations can save you thousands of dollars. Evaluate the entire system to find the best solution. Try our free digital tool, MyDrive® Harmonics.

In an installation, energy consumption is a major contributor to the operating costs. That is why validation of efficiency, including calculation of energy losses, is an important step when choosing equipment to mitigate harmonics. Efficiency of 6-pulse drives normally differs by only 0.5% between different variable speed drive suppliers. However, efficiency variations of as much as 1-2% are not unusual in mitigation equipment from di­erent suppliers. It’s important to do the calculations before you make your choice.

Use harmonic mitigation only when needed

Find the balance between total harmonic distortion (THDi), efficiency, and the cost of purchased equipment. For transformer load below 40%, and 5% THDv limit, typically no mitigation is required. Standard 6-pulse drives with chokes can be enough to deal the harmonics present, in these cases.

Don’t buy what you don’t need. For help in calculating when to mitigate, contact us.

Analyze at full load current where THDv impact is highest

Design the system to withstand the full load worst case requirements from the driven load(s) and other loads.

Use calculation tools to dimension transformers and generators, or test the capacity of items already chosen.

Adjust and iterate the mitigation equipment scenarios to meet a suitable cost and performance outcome.

To find different mitigation scenarios, use MyDrive® Harmonics.

Target THDv of 5% for best cost / performance balance

THDv of 5% is a good compromise between lowest distortion levels, the cost of the equipment needed to reach that level, the resultant efficiency of the components chosen,  and the overall system efficiency.

Driving the distortion lower follows the law of diminishing returns. It’s possible to reduce distortion levels even further, but the gains can cost too much.

To calculate energy efficiency of your application, try MyDrive® Energy.

What’ s new in variable speed drive technology?

Today, harmonic mitigation in drive systems has improved. Variable speed drive systems optimized for low-harmonic performance can now operate at 3-5% total harmonic distortion (THDi), at unity power factor, with lower common mode impact, and lower supra harmonic impact. Drives can also eliminate the full load current impacts caused by direct-online (DOL) motor starting. All of this means that supply transformers and backup generators can be dimensioned significantly (10-30%) smaller. Cables, fuses and switchgear can also be smaller. These components are expensive and can affect the ability to meet the budget constraints of a project. Careful, early drive (VFD) selection can therefore play a major part in ensuring project success.

Is harmonic distortion costing you money and downtime?

Factors impacting choice of harmonic mitigation methods include: compliance load profile, power factor distribution,  electrical grid conditions, physical size of the installation (especially for retrofits), efficiency, and performance of power systems.

Need advice on harmonic mitigation? Contact us today

Drive interact

Harmonic mitigation: When designing a system, plan the drive (VFD) first

Using new drive technologies, you can mitigate harmonics while saving significantly on sizing and dimensioning of the electrical network.  Therefore, to optimize the overall electrical system, it is vital to select the drive (VFD) early in the power system design phase. Drives offer much more than just turning your motors.

Discover more
Optimize electrical system design

Optimize electrical system design

When designing an electrical system, optimizing for harmonic mitigation also means optimizing system design for cost, power quality, and Scope 1, 2, and 3 emissions. Whether for new-build or retrofit, design the electrical system to ensure:

  • Reduced initial up front capital cost
  • Minimal long-term operational costs
  • Minimal practicable impact of harmonics from drives on the supply network and the wider system, including driven loads

Consider the needs for lower greenhouse gas (GHG) emissions in accordance with legislation.  The design must also match the ambition of the site (or client) to meet their Scope 1,2, and 3 (GHG) emission targets, and commitments to achieve carbon net zero.

Plan a new build

Save money on large investments

For new builds, specifying the right low-harmonic drive means you can dimension generators and transformers smaller and save money on the large capital investments.

Early considerations on grid power quality allow for cost-optimized mitigations, such as combining AFE drives, active filters, passive filters and 6-pulse drives, to achieve the most cost-effective, compliant solution.

Contact us for advice

Select drives early. Danfoss can help you reduce total harmonic distortion in the best way.

The drives you select can make a big difference to the overall design. Consider the drives early in your project design by including electrical engineers in your initial planning. With good preventive measures in place, you can reduce dimensioning of the whole switchgear transmission chain for optimal CAPEX. Use the Danfoss tool MyDrive® Harmonics or contact your local office for expert advice in using harmonic calculations to dimension smaller transformers and generators.

Downsize transformers and generators by up to 30%

Downsize transformers and generators by up to 30%

  • To design a greenfield system, it is imperative to consider the VSD topology as early as possible.
  • By considering the VSDs (and filters) early, you can downsize transformers and generators by 10-30% compared with conventional approaches. Switchgear dimensioning is also affected.
  • Refine the design to obtain maximum benefits by placing centralized filters strategically, and deciding when to use AFE technology to best advantage.

Plan the drive first: Then dimension other system components

When you design systems for harmonics compliance, choosing the best drive for variable speed control will reduce total harmonic distortion (THD). By reducing THD, you can optimize the dimensioning of every other component.

Using the right ultra low-harmonic or traditional drives, you can reduce the cost of buying and running

  • Supply components
  • Network components
  • Motors and driven loads

Follow these 3 steps

Follow these steps to select the drive and filter early, then reduce dimensioning of all other equipment for maximum benefit. Or contact Danfoss for design support.

Carefully select the drive and filter to balance capital cost and system benefits. Do not over-compensate for harmonics.

Drives from Danfoss are compatible with all motor types, to ensure you can select the best motor technology for the task, with no barriers. Carefully select the motor and driven load to balance capital cost, best efficiency and optimal maintenance effort. Avoid oversizing motor and drive as this gives the best harmonic footprint and keeps CAPEX as low as possible.

Your benefits:

  • Lower operating costs (OPEX), affinity laws, less wear and tear on motors and driven loads, fewer breakdowns.
  • Optimal speed control to reduce energy consumption and reduce Scope 2 direct emissions drastically.
  • The drive offers a range of other features such as Condition-based monitoring integrated in the drive, for early warning of motor wear, and fewer failures.
  • By choosing a drive with built-in grid meter, it is possible to monitor the voltage quality during operation and get notified if installation efficiency can be improved by adding extra central mitigation equipment.

Emission and cost impact:

  • Balance CAPEX and benefits.
  • Reduce Scope 3 third-party emissions significantly: sourcing, repair and replace emissions.

Did you know it’s possible to scale down the dimensioning of transformers and backup generators, when distortion levels from drives and harmonic filters are low? By taking measures to downscale transformer or genset size, you can reduce both capital cost (CAPEX) and operating cost (OPEX) with a range of other benefits too:

  • Improved efficiency with less heat generated
  • Reduced Scope 2 direct emissions (energy/fuel)
  • Reduced Scope 3 third-party emissions (sourcing, repair, and replacement)

Downsize your network components such as switchgear, e-rooms, MCCs, fuses and cables, by ensuring that the harmonic frequencies and distortion levels from drives and filters are low.

Emission and cost benefits for your project:

  • Reduced capital cost (CAPEX) and lower losses created
  • Lower operating costs (OPEX), less heat generated, and higher efficiency
  • Reduced Scope 2 direct emissions (energy/fuel)
  • Reduced Scope 3 third-party emissions (sourcing, repair, replacement, and recycling)

Lower operating costs, by properly using connected equipment, controlling driven loads and minimizing network issues.

Emission and cost benefits:

  • Reduce OPEX
  • Reduce Scope 1 and 2 emissions (direct and indirect emissions)

Plan an upgrade

Choose wisely for significant OPEX savings

In an upgrade project, typically you need to maximize the impact of the retrofit without overloading the existing electrical infrastructure.

The right choices can reduce your operating costs significantly. Choose the right drives to prevent the upgrade from overloading your system. Consider aligning with a company like Danfoss, that understands the problem and can offer the full range of solutions available - because system scenarios differ, and each solution has its merits.

Contact us for advice

Follow these 3 steps

  1. To connect additional drives (VSDs) to existing transformers, it is imperative to know the existing load on the transformer
  2. Perform a harmonic survey to determine the level of distortion already present. Use the MyDrive® Harmonics tool to determine the impact of harmonics on your system, then estimate the benefits of harmonic mitigation solutions from Danfoss
  3. Design the system to “clean up” any existing harmonic distortion, as well as ensuring the new drive load can be added with no issues

With a wide portfolio of mitigation technology choices, you have the freedom to select the best approach. Danfoss offers support for your system design and delivers the full range of mitigation solutions.

Contact us for advice.

Maximize system performance with our harmonic mitigation solutions

Harmonics in water & wastewater installations
Harmonics in water & wastewater installations

Choose wisely to curb costs

Harmonics in HVAC applications
Harmonics in HVAC applications

Surprisingly simple ways to reduce costs

Case studies

How a new water pumping station keeps supply flowing in Bern

SWITZERLAND: The Wehrliau pumping station in Bern delivers up to 1.20 M liters of drinking water hourly. iC7 drives play a key role in ensuring reliable supply.

Read the case story

How does Beat the Storm deliver more fun for less CO2?

DENMARK: Universe Science Park saves on both power bill and emissions for its wind tunnel attraction “Beat the Storm”, with the intelligent VLT® HVAC drive.

Read the case story

Danfoss compressor control ensures optimal comfort for hospital patients and staff

In the University Medical Centre (UMC) Ljubljana air conditioning system, Danfoss drives with integrated filters ensure low harmonic distortion, with maximum THDi of 5%. 

Read the case story

How did Sincrondraiv SRL improve irrigation pumping efficiency by up to 40%?

ROMANIA: Digitizing irrigation systems helps farmers achieve better harvests. Pumping stations now use 30-40% less energy and use water more efficiently too.

Read the case story

Accurate control of CT Offshore’s ROV trencher

VLT® AutomationDrive FC 302 and VLT® Soft Starter MCD 500 provide quick and accurate control of high- and low-pressure seawater pumps on the remotely operated trencher laying HVAC subsea cables.

Read the case story

Rock-solid reliability underpins sustainable aquaculture at Nordlaks

NORWAY: VLT® AQUA Drive FC 202 ensures dependable uptime with stringent harmonic compliance at Nordlaks Smolt AS.

Read the case story

Jersey Water desalination plant boosts efficiency by 38%

UNITED KINGDOM: Jersey Water chose VLT® AQUA Drive from Danfoss when needing a major upgrade at its La Rosière desalination plant.

Read the case story

Want to learn more about harmonic distortion?

Watch the interview and discover what our expert has to say about harmonic interference and total harmonic distortion, and how to tackle it in the most energy-efficient way possible — while optimizing your system.

Shine a light on your system performance

Use the MyDrive® Harmonics tool to calculate harmonic frequencies and interference in your system — and design a harmonic mitigation solution fit for your needs. Simply use the power circuit simulator included to perform a simulation of your system so you can pinpoint where changes need to be made. And control the harmonics generated in the most efficient way possible.

Learn about MyDrive® Harmonics

Related products

Danfoss offers a full portfolio of products for harmonic mitigation in high and low power ranges, compatible with all motor types. The range includes low harmonic drives, active frond-end drives, active and passive filters, and input and output filters.  Our DrivePro® service offerings also support you in ensuring smooth operations and product longevity. DrivePro® services help to identify potential issues caused by excessive harmonic distortion, combined with recommendations for dedicated mitigation actions.

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    Take the complexity out of commissioning with DrivePro® Start-up’s full range of health checks and adjustments. Our DrivePro® experts inspect and test your AC drive and motor performance to ensure the best configuration of your AC drives.

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    Even the best performing AC drives need protection. DrivePro® Extended Warranty offers a wide range of warranty options and provides the longest coverage in the industry. Enjoy better uptime, repairs, replacements, and spare-part support for up to six years.

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    Optimize your maintenance strategy with a complete onsite survey and risk analysis of all your AC drives collected in one detailed report. Together with a Danfoss expert, you can build a tailored plan for future maintenance, retrofits, and upgrades based on your exact needs.

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    Even the best performing AC drives need protection. DrivePro® Extended Warranty offers a wide range of warranty options and provides the longest coverage in the industry. Enjoy better uptime, repairs, replacements, and spare-part support for up to six years.

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    DrivePro® Site Assessment

    Optimize your maintenance strategy with a complete onsite survey and risk analysis of all your AC drives collected in one detailed report. Together with a Danfoss expert, you can build a tailored plan for future maintenance, retrofits, and upgrades based on your exact needs.

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    With secure access to your system, our engineers can connect to your AC drives from any off-site location to deliver rapid support and get you up and running in no time.

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Explore more about harmonic mitigation
What is harmonic distortion and why does it matter?

Harmonic distortions affect the mains power network, causing poor power quality, unreliability, and potential equipment damage. Danfoss can help you to reduce the effects of harmonics.
Is harmonic distortion costing you money and downtime?

Have you experienced sudden production outages? The cause is often poor network quality due to harmonic distortion. VSDs can mitigate harmonics for more stability.

Contact us