reactive power compensation harmonics and harmonics...

Thomas Gsell

November 2013

Reactive Power CompensationHarmonics and Harmonics Filtering

IIEE 38th Annual National Convention and 3E XPO

© ALSTOM 2013. All rights reserved. Information contained in this document is indicative only. No representation or warranty is given or should be relied on that it is complete or correct or will apply to any particular project. This will depend on the technical and commercial circumstances. It is provided without liability and is subject to change without notice. Reproduction, use or disclosure to third parties, without express written authority, is strictly prohibited.

Harmonics and Harmonics Filtering, IIEE, November 2013 – Slide 2

Alstom GridEquipment & services for power generation

Alstom Thermal Power

Equipment & services for rail transport

Equipment & services for power transmission

Alstom Renewable PowerAlstom Transport

Three main activities in 4 sectors



ALSTOM Grid Ltd. Tampere, Finland

Employs around 300 people in Tampere and Vantaa

Sales office of other Alstom Grid products in Vantaa

Turnover of 68 million EUR year 2012-13

Exports account for 95 % of the output

Main market areas: Scandinavia, Europe, Asia, Russia, Alstom Grid



Alstom Grid – Tampere offering

Reactive Power Compensation Power Electronics Activities

LV products up to 1kV

− LV capacitor units− LV reactors− Electronic products− LV capacitor banks− LV active filters

HV products up to 145kV

− HV capacitor units− HV reactors− Electronic products− HV capacitor banks

Compensation systems

− Static Var Compensators (SVC)

• Industrial SVCs• Utility SVCs

− SVC MaxSine (STATCOM)− Series capacitor banks

HV products over 145kV

− HV capacitor banks



There are three kinds of reactive power:

Reactive Power

− Inductive Fundamental Reactive Power (Q1L)

=> Sinusoidal current, phase shifted from voltage to the right

− Capacitive Fundamental Reactive Power (Q1C)

=> Sinusoidal current, phase shifted from voltage to the left

− Harmonics Reactive Power (D)

=> Non-sinusoidal current

22

1 DQQ 2111 CL QQQ



Inductive Reactive Power

S

Uq

R

L

iL

uL

Uq uL

iL

L

uL;iL

t

iL

uL



Capacitive Reactive Power

S

Uq

R

C

iC

u

Uq uC

iC

C

uC;iCuC

iC

t



Harmonics Reactive Power

uq, uL, iL

-400

0

400

uq, uL, iL

-400

0

400

uq, uL, iL

-400

0

400

uq, uL, iL

-400

0

400

Firing Angle: 140°Firing Angle: 120°Firing Angle: 90° (half power) Firing Angle: 30°

Dimmer




t

IL

Dimmer with smoothing reactor




UL2-L3

UL1-N

UL2-N

N

UL3-L1

L3

UL3-N

L1

IL2

L2

UL1-L2

IL1

MIL3

t

IL1,2,3

3-phase dimmer; Thyristor-DC-Drive




q

Iq

-

+

IR

C R UR

1-phase B4 diode rectifier




3-phase B6 diode rectifier

t

IL1,2,3



Harmonics power consumers are:

Non-Linear Loads

− etc.

− Drives (frequency converters, DC-drives)

− Dimmers

− Power supplies (computers)

− Furnaces (induction furnaces, arc furnaces)

− Lightings (gas-discharge lamps, fluorescent tubes)

− Diode Rectifiers



Harmonics Theory

A harmonic is defined as a sinusoidal wave with a certain amplitude and an integer (whole number) multiple of a fundamental frequency. A harmonic is a component of a periodical signal with a fundamental frequency.If the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, 5f, etc.

The mathematical procedure to calculate amplitudes and frequencies of harmonics is the “Fourier Transformation”!



Fourier Transformation

1st+3rd+5th+7th+9th+11th+13th1st1st+3rd1st+3rd+5th1st+3rd+5th+7th1st+3rd+5th+7th+9th1st+3rd+5th+7th+9th+11th1st+3rd+5th+7th+9th+11th+13th

1st3rd5th7th9th11th13th



Fourier Transformation

= 1st+3rd+5th+7th+9th+11th+13th

1st

+3rd

+5th

+7th

+9th

+11th

+13th



Harmonics Data-Demonstration



Fundamental reactive current as well as harmonics reactive currents cause stress to:

What’s up with Reactive Current?

What means “reactive” power?

− Lines− Transformers− Generators− etc.

The product of a sinusoidal alternating voltage with a alternating current contributes no power if that current is a reactive current. In this case only reactive energy flows - there is no net transfer of energy to the load.Also known as idle current; quadrature current; watt-less current.



Active Power

Voltage

x

Current

=

Power



Inductive Reactive Power

Voltage

x

Current

=

Power



Capacitive Reactive Power

Voltage

x

Current

=

Power



Harmonics Reactive Power (5th)

Voltage

x

Current

=

Power



Voltage

x

Current

=

Power

Harmonics Reactive Power (7th)



Voltage

x

Current

=

Power

Harmonics Reactive Power (5th + 7th)



In contrast to fundamental reactive current, harmonics currents cause harmonics voltages which cause disturbances to consumers installed in the same electrical network:

Harmonics Consequences

Finally triple harmonics cumulate in the neutral wire which causes overload and dramatic consequences:

− Reduction of the life span and thus premature failure of condensers and electric motors due to thermal overloading

− Malfunctioning with electronics− Malfunctioning of protection device− Malfunctioning of ripple control systems− Impairment of the ground fault deletion

− Cable fire− Transformer breakdown− Noise emission



Why harmonics currents cause harmonics voltages in electrical networks?



- Active harmonics filters

Basically there are two possibilities to compensate harmonics currents:

What to do against harmonics?

- Passive harmonics filters (tuned parallel resonance circuits)



Passive harmonics compensation(tuned parallel resonance circuit)



Active harmonics compensation with MaxSine



Active Filters: Pro and Contra

Active Filters Advantages:

Disadvantages:

− Direct compensation of harmonics currents− Easy dimensioning− Independent from the mains voltage quality− Independent from the network impedance− Excellent dynamics− No influence to ripple control systems− Electronic overload protection− No capacitive reactive power injection− Compensation possibility close to consumers

− More expensive (than passive filters)− Higher power losses− Ripple current



To measure harmonics voltages and currents the following equipment can be used:

Measuring Harmonics

Total harmonics distortion factor (THD)Europe: THDR, USA: THDF

− Oscilloscope (the data can be analyzed after the measurement results were stored)

− Power meter (“Fluke”, “Tektronix” etc.)− Data logger (“TOPAS”, “Dranetz” etc.)

2

2

1

1

2

1

2

1;;

F

FRFR

THD

THDTHD

I

I

THDI

I

THD

2

2

1

1

2

1

2

1;;

F

FRFR

THD

THDTHD

I

I

THDI

I

THD

%-THD may not contain a sufficient informative value for currents. An absolute harmonics THD-value in Amperes may be preferred instead!



Power:

Calculating Power

Power factor:

1

2

111

11

;sin

cos;

IUDIUQ

IUPIUS

22

1 DQQ 22

1

2 DQPS

1

2 cos1 RTHDS

P



Slip-up’s with Harmonics

− No differentiation in between THDR and THDF

− No differentiation in between Q and Q1

− No differentiation in between γ and cosφ− No differentiation in between RMS- and peak-values of Fourier

Transformation results− Meaningless usage of current THD values



Stand Alone MaxSine Compact Module

New Active Filter “MaxSine”

MaxSine100AV6C

MaxSine100AV6CE



MaxSine Compact Cubicle Version




Main Features

− Small size enables customized modular cabinet construction

− Ethernet connection and Web Server for monitoring, setting and control• User interface: PC or optional HMI

− Several menu languages (also character languages)− Relay output for run indication− Standby in case of small load current

− Adjustable relay output for cubicle fan− Selectable dual parameter page setting e.g. for emergency generator

supply

− Devices available for 3-wire as well as 3-wire + neutral (4-wire)

− Several overload protection algorithms:• Output limiting factor by current peak• Output limiting factor by temperature• High temperature switch-off




Compensation Features

− Two compensation modes:• Fast mode, selectable harmonics, amplitude and phase, 1-50th• Ultra fast mode, global compensation

− Adjustable output overall factors for amplitude and phase

− Total power factor can be forced to 1− Possibility to balance line currents− Ability to eliminate neutral current

− 6 current inputs for multiple circuits (open loop, closed loop, CT-additions, etc.)

− Excellent dynamics; Response time < 1ms in ultra fast mode and adjustable from 1 network period to 50 network periods in fast mode

− Selectable current input sensors:• Rogowski coils• Current transformers (CTs)

− Selectable compensation priorities:1. Fundamental has priority2. Harmonics have priority3. Only fundamental4. Only harmonics




Extended Measurement and power meter functions− Date/Time

− Load, network and compensation currents in phases and neutral• RMS, fundamental, harmonics currents and crest factors

− Active, reactive, apparent and harmonics power, cosphi− THD(u), THD(i), current and voltage harmonics spectrum

up to 50th harmonics− Waveforms of currents− Cabinet temperature and external temperature (e.g. heat sink) if

sensor connected− Uploading of measurements for reporting

− Network mains voltages

− One set of measurement values is always saved to memory when system stops




Active Filter Applications

Frequency Converter




Network current (frequency converter)before and after compensation with MaxSine



Fourier transformation of frequency converter currentbefore compensation


Order: f / Hz I RMS / A THDr: THDf: Total-

values:

1 50 35,50 91,55% 100,00%

3 150 0,52 1,33% 1,45% I RMS / A:

5 250 14,57 37,57% 41,04% 38,77

7 350 5,25 13,55% 14,80%

9 450 0,08 0,20% 0,22% THDr:

11 550 1,93 4,98% 5,44% 40,51%

13 650 1,03 2,66% 2,91%

15 750 0,10 0,25% 0,27% THDf:

17 850 0,92 2,37% 2,59% 44,24%

19 950 0,52 1,33% 1,46%

21 1050 0,08 0,20% 0,22%

23 1150 0,51 1,31% 1,43%

25 1250 0,33 0,86% 0,94%



Fourier transformation of frequency converter currentafter compensation


Order: f / Hz I RMS / A THDr: THDf: Total-

values:

1 50 36,91 99,49% 100,00%

3 150 0,16 0,44% 0,44% I RMS / A:

5 250 0,27 0,73% 0,73% 37,10

7 350 0,27 0,73% 0,73%

9 450 0,12 0,33% 0,34% THDr:

11 550 0,16 0,43% 0,43% 3,20%

13 650 0,16 0,43% 0,43%

15 750 0,17 0,46% 0,46% THDf:

17 850 0,34 0,91% 0,92% 3,22%

19 950 0,03 0,08% 0,09%

21 1050 0,12 0,33% 0,33%

23 1150 0,14 0,38% 0,38%

25 1250 0,26 0,69% 0,70%



Personal Computers




Network current (Personal Computers) before and after compensation with MaxSine




Dynamic DC-Drive




Network current (dynamic 3-phase load) before and after compensation with MaxSine


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