Understanding Harmonics in Electrical Power Systems for...

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Understanding Harmonics in Electrical Power Systemsfor HVAC experts.

Royce MeiliDanfoss DrivesTrane CSO Global Account Manager(316) [email protected]


Harmonics in Building Electrical Systems

The Cause

The Effects

The Standards

The Solutions


Introduction – Why Harmonics?

• VFD controlled motors saves up to 60% of the energy consumption in pump and fan applications.

• VFDs have a side effect –Harmonics.

• Harmonics prevent energy savings.

• Harmonics effect quality of the electrical energy in the power supply.

• Limiting of Harmonics is also required to ensure safe operation of the installation.


Utility power is delivered to a facility

• Voltage is delivered in sinusoidal form, at 60Hz.

• Electrical loads are designed to operate at this frequency and draw sinusoidalcurrents.


Two Types of Electrical Loads

Linear loads Linear loads are resistive, inductive or capacitive loads. They consume current equally through each power phase.

Draws power evenly.

Non-Linear loads Non-linear loads contain switching devices that will consume current unevenly between phases.These cause harmonic distortion.

Draws power unevenly.


The Challenge: Growing addition of non-linear loads.

As more electronic equipment is installed in buildings there is a greater potential for the effects of harmonics to be seen in the electrical system.

70%

30%

1990's

95%

5%

1960's

40%60%

2000'sVolume of Non-Linear Load Growth in USA

Linear Load

Non Linear Load



The Cause

The Effects

The Standards

The Solutions


Harmonic distortion by nonlinear loads

Harmonics created at the non-linear load are reflected upstream to other devices in the electrical distribution system.

Background distortion possible

UtilityTransformer

Linear-Load Motor

Linear-Load Motor

Disturbance to otherdevices

Current Distortion

Affects device level performance.

Voltage Distortion

Affects system level performance.


Ideal 3 Phase Sine Waves


The Effects of High Harmonics

Current distortion causes Extra heating of power

transformers

Nuisance tripping of relays and circuit breakers

Cable heating

Causes voltage distortion

Resulting in Equipment downtime

Premature component failures

Higher utility costs

Impacts other customers served by the utility provider.

Voltage distortion Effects other devices connected to the

building’s electrical system.

Cause malfunctioning of sensitive electronic devices: servers, security systems, telecom, MRI, etc.

Can effect devices that rely on timing from a clean sine wave


According to IEEE – Harmonics Will Cause:

• Distortion of mains supply voltage, • Unwanted currents flowing in the supply

network generate additional energy lossesLoss of Energy

• Additional acoustic noise from motors and other apparatus, reducing the efficiency of motors.

Inefficiency of Motors

• High harmonic amplitudes may not only cause malfunctions, additional losses and overheating, but also overload the power distribution network and overheat the neutral conductor and cause it to burn out.

Increased Operating Cost

Loss of Money



The Cause

The Effects

The Standards

The Solutions


IEEE-519-2014 is the standard.

IEEE – 519 2014 goals: Defines the specific and separate

responsibilities for utilities and users; to maintain the voltage THD within

acceptable limits at the Point of Common Coupling (PCC);

to protect the user and utility equipment from the negative impact of harmonics.

The individual responsibilities are: User - limit harmonic currents at the

PCC to prescribed levels Utility - limit voltage distortion at the

PCC to prescribed levels by maintaining system impedance as necessary


IEEE 519-2014 Harmonic Guidelines

IEEE 519-2014 Standards and Recommendations• Concerned with the Point of Common Coupling (PCC).

(The point where the utility service connects to the customer.)

• The goal of the standard is to limit voltage distortion at PCC1:

Medium Voltage Level

Low Voltage - Plant Level

Equipment Level


Current distortion Limits for General Distribution Systems (120V through 69 kV)

Maximum Harmonic Current Distortion in Percent of IL

ISC/IL <1111<=h<1

7 17<=h<2323<=h<3

535<=h<=5

0TDD (%)

<20 4 2 1.5 0.6 0.3 5

20<50 7 3.5 2.5 1 0.5 8

50<100 10 4.5 4 1.5 0.7 12100<100

0 12 5.5 5 2 1 15

>1000 15 7 6 2.5 1.4 20

Even harmonics are limited to 25% of the odd harmonic limits above

IEEE 519-2014 recommended limits:

Rsc = ISC / ILISC=maximum short circuit current at PCCIL=maximum demand load current (fundamental frequency component) at PCC


MCT-31 Harmonics CalculationModule

Designed to give a valuable estimation with less then 5-10 parameter settings

Has been designed with a high focus on userfriendliness

Does not need support from advanced calculation resources, which allows for usage on a laptop


Harmonic Analysis

• May be required as part of VFD submittal.

• Info needed to perform analysis:- Transformer kVA and

impedance.- List of VFDs you are

providing.- VFD specs.

• Shows harmonic contribution of the VFDs being provided.



The Cause

The Effects

The Standards

The Solutions


Limiting of Harmonics

Active Front End

Low Harmonic Drive

Two solutions are possible: Compensation at the

Point of Common Coupling (PCC)

Point-of-Load Compensation (PLC)

6-pulse Drives or Drives with 5% Passive Filters

PCC Compensation

PLC compensation

Notes: there are no regulations, which require THDi≤5% at drive terminals.

PLC compensation

Limiting harmonic currents (IEEE 519)

Customers Needs:


Mitigation solutions

All Trane Drives have dual DC-link reactors (chokes) as standard feature. This provides the equivalent harmonic filtering to a 5% line reactor without reducing input voltage or increasing heat generation.

This cancels the need to oversize input cables and provides improved system efficiency.

Technology is good for: Many drives on the same transformer Prolonged product life Perfect motor control

Slightly increase in drive size and weight than a drivewithout a choke

Weakness

Efficient Long lifetime Smoothest possible DCBuild-in Little impact on grid distortion

Strength

TraneIntegrated Solution

<45%

Total harmonic distortion of drives with DC or AC choke

DC drive current waveform

Dual DC Link Reactors $



Passive filters installed ahead of VFD.The absorption circuit is designed to reduce all harmonics.

Requires additional field wiring.

Technology is good for: For drive currents <370 ADrives loaded 40-100% In balanced applications with THDv <5%Drive packages <200 kW

Possible leading power factor at light loads.

Load dependent performance Added electrical wiring costs Limited enclosure types

Weakness

Easy add-onRobust & efficientBetter performance than

other passive filters at light loads

Use when the loading is 40–100%.

Strength

Trane Field Installed Solution

AHF010 AHF005

<5%Total harmonic distortion with AHF005

<10%Total harmonic distortion with AHF010

Passive Filters – Field Installed $$



TR200 drive with 5% passive filter in single enclosure.

Technology is good for:For drive currents <730 A (600 HP)Drives loaded 40-100% In balanced applications with THDv <5%NEMA 1, 12, 3R

Load dependent performance

Limited enclosure types

Weakness

Single point power Uses standard 6-pulse

drive and components.Use when the loading

is 40–100%.Options for disconnect,

bypass, dV/dT filter

Strength

Trane Custom Built-up Solution

<5%Total harmonic distortion above 60% load

Preferred Harmonic Design (PHD) $$$



High power 12 & 18 pulse drives First technology widely adopted and has become the American standard for harmonic mitigation.

Technology is good for:High Power applications: >400A. Loading of drives between 50-100%Balanced application with THvD of <5%Drives packages >300 A

Higher heat productionLoad dependent

performanceNot ideal if grid voltage is

unbalanced or distorted

Weakness

RobustNo resonance pointLow Cost at high powerHigh Efficiency

Strength

TraneCustom Solution

12-pulse drive current waveform

≈12%Total harmonic distortion of drives with 12 pulse rectifier

≈ 7%Total harmonic distortion of drives with 18 pulse rectifier

Multi-Pulse Drives $$$$



Advanced Active Filters have been designed to meet IEEE 519 requirements. AAFs are installed parallel to loads and are perfect for compensating multiple loads simultaneously.

Technology is good for:Group compensation of drives460 VAC 115 – 320 Amp RangeUp to four units can be paralleledApplications always running at partial loadGood retrofit solution

Not a ‘point source’ device for smaller VFDs

Possible resonances with grid equipment

Increasing cost and complexity.

Weakness

THD of 5% or less achievable Highest immunity

against grid and load variationsParallel device which

can’t ‘overload’

Strength

Trane Custom Solution

<5%Total harmonic distortion. Ability to scale

Advanced Active Filters (AAF) $$$$

An Active Filter can be compared to a set of noise cancelling headphones.


Harmonics Solutions Portfolio

Notes:PLC … Point-of-Load Compensation

PCC … Point of Common Coupling

Solution PLC PCC Comments

Passive Filter √ Separate, field installed item Simplicity, traditional, and cost effective

PHD–Passive Filter √ Combines TR-200 VFD with Passive Filter

in single enclosure. Simple technology.

Multi-Pulse √ Traditional, and cost effective for high power applications.

Active Filters √ √ Ability for costs optimizations, ensure 40-60% lower space and highest

operation safety


Mitigation SummaryNo Consideration

1. THvD need

2. Compliance need

3. Mains voltage & tolerance

4. Max voltage unbalance

5 Max grid pre-distortion

6 Generator run/back-up

7. VFD bypass need

8. Displacement PF / Reactive control

9. Amount of loads to be corrected

10. Application/load dynamics

11. Enclosure need

12. Cooling air and segregation need

13. Max ambient temperature

14. Physical size available

15. Efficiency target

16. Initial cost vs running expenses

17. Isolation needed

18. Regeneration need

There is no single solution that:

• Gives the best performance• At the lowest cost• With highest system efficiency• And satisfies all norms• Which is applicable to all size of drives• And can be used in new and retrofit

…………

The “best” fit is found considering the application, grid, and site aspects.


Additional Resources

• Trane Engineering Newsletter, Vol 47-1- A primer for non-electrical

engineers Harmonic Distortion in Electrical Systems

- ADM-APN065-EN (March 2018) • Trane White Paper – Harmonics in

AC Systems, by Ben Sykora. Dec. 2014

• Danfoss Whitepaper- Harmonic Distortion of the AC

Power Line- Copyright 2011


So, what should I do?

1. Review the VFD specifications2. If in doubt – ask for our review3. Take Exception to the harmonics requirement in

the specification:- The specs call for the VFDs to meet IEEE 519

standard. Since IEEE 519 is a systems standard and not a component standard, compliance cannot be determined until a harmonic analysis is performed. This requires knowing the transformer kVA and impedance rating. Once this information is provided an analysis can be performed. If additional harmonic filtering is required it can be provided at an additional cost.


Your Dedicated Sales Support Team

• Pricing on Projects- Send us the VFD specs, schedules or the list of VFDs with the

details. (Don’t send the complete bid packet.)- Custom quotes – (allow 2-3 days)

• Submittal Creation- Send us the quote or list of VFDs and the VFD Specs.

• Harmonic Analysis- Need: Transformer kVA and impedance rating, list of VFDs and

the VFD spec requirements.• Your “Go To Team” for all things Trane Drives.

Tim Whitford• Trane Inside Sales Engineer

- Direct 815-639-8961- [email protected]

Royce Meili• Trane CSO Global Account Mgr.

- Cell: 316-633-3256- [email protected]

tel:815-639-8961

mailto:[email protected]

Thank you

Royce MeiliDanfoss Drives

Trane CSO Global Account Manager(316) 633-3256

[email protected]

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