L&T Electrical & Automation
Power Quality Solutions
4 December 2023
Power Factor Correction – kWh & kVAh
Power Factor
𝒌𝑾
𝒑𝒇 =
𝒌𝑽𝑨
kVAh
kVArh
kWh
Benefits of LT compensation over HT compensation
LT Compensation benefitting your Transformer
- Improves operating Power Factor - Increases kVA capacity
- Reduces line current – optimizing Main Incomer switchgear
ratings
- Reduces Copper losses
- Reduces Operating temperature - ensures longer life.
- Maintenance of LT capacitors is easier
- Spares and Accessories are available easily at lesser price
Overview of Harmonics
3 Phase AC/DC
SMPS, CFL drives
lamps, UPS /converters
Arc/Induction
Furnace
Current Harmonics
Transformer /
Cable
Impedance
Voltage Harmonics
Higher Harmonics reduce PF, in turn increasing kVAh
This will erode THD-I Displacement PF Distortion PF True PF
the savings you 5% 0.999 0.999 0.998
have planned
30% 0.999 0.958 0.957
40% 0.999 0.929 0.928
True PF
PF due to
reactive
current Due to
harmonics
Penalty on Harmonic Levels – Future plan of all ERCs in India
New CEA regulations on
PSERC Gazette on Harmonics
Power Quality
Sept 2020
Feb 2019
Currently, Notice to customers on installation of Power Quality Meters
6
IEEE 519 limits for Current Harmonics - Penalty
Maximum Harmonic Current Distortion in % IL
where
Isc = maximum short-circuit current at PCC
[Can be calculated as MVA/(%Z x V)].
IL = maximum demand load current
(fundamental frequency component) at PCC.
Power Quality Analyzer (PQA) - WC8000
PQA Features
Accurate Power Quality
measurement Parameters- Analysis Reports
• Class A as per • Transients
IEC61000-4-30 • Flickers • EN50160
• Class 0.2s as per • Sag Swells • IEEE 519
62053-22 • Harmonics upto • Power Quality
• Power quality 50th on screen and Events
measurement as 127th on Webpage • Data logging
per IEC 62586-2 • TDD
Webpage Glimpse
Webpage Glimpse
Optimum solutions for Power Quality– Hybrid
To minimise kVA consumption and achieve True PF - close to unity.
THD-I Displacement PF Distortion PF True PF
5% 0.999 0.999 0.998
30% 0.999 0.958 0.957
40% 0.999 0.929 0.928
kVAh billing
Adding more capacitors to improve Displacement PF will further
kWh billing
reduce True PF, due to harmonic amplification!
Working on penalty
IEC 61439 & IEC 61921
for Harmonics
𝐓𝐫𝐮𝐞 𝐏𝐨𝐰𝐞𝐫 𝐅𝐚𝐜𝐭𝐨𝐫 = 𝐃𝐢𝐬𝐩𝐥𝐚𝐜𝐞𝐦𝐞𝐧𝐭 𝐏𝐅 × 𝐃𝐢𝐬𝐭𝐨𝐫𝐭𝐢𝐨𝐧 𝐏𝐅
𝐀𝐜𝐭𝐢𝐯𝐞 𝐏𝐨𝐰𝐞𝐫 𝟏
𝐃𝐢𝐬𝐩𝐥𝐚𝐜𝐞𝐦𝐞𝐧𝐭 𝐏𝐅 (𝐂𝐨𝐬Ø) = 𝐃𝐢𝐬𝐭𝐨𝐫𝐭𝐢𝐨𝐧 𝐏𝐅 =
𝐀𝐩𝐩𝐚𝐫𝐞𝐧𝐭 𝐏𝐨𝐰𝐞𝐫 𝟏 𝐢𝐓𝐇𝐃𝟐
Power Capacitors + Detuned reactors to
compensate reactive power & avoid harmonic AHF to mitigate
amplification. harmonics currents.
Capacitor model
500
LTXL Ultra Heavy Duty
(Non – Linear load > 30%)
450
Steel plants, Automobile, Cement
plants, Fabrication industries, Machine
400 Super Heavy duty tools, Glass industry,
(Non – Linear load: 15 to 30%)
350 Textile mills, Pharma, Paper mills,
Food & Beverage, Oil mills
PEAK INRUSH
Heavy duty, Gas filled
CURRENT
300
(Non – Linear load: 5 to 15%)
Process industries, commercial buildings with considerable
250 harmonic content
200 Standard duty (Non – Linear load < 5%)
SMEs with very less Harmonic content.
150 3-in-1 Capacitor for fixed compensation
100
50
1 1.5 2 2.5 3 3.5
OVER CURRENT
Comparison of Capacitor Specifications
Standard Duty Heavy Duty Gas filled Super Heavy
LT-APP LTXL-
Duty
Ultra Heavy Duty
Overcurrent 1.5 In 1.8 In 1.8 In 2.5 In 2.5 In 3 In
Peak Inrush
200 In 250 In 300 In 350 In 300 In 500 In
Current
Permissible
+10% (8h/24h), +15% (30m/24h), +20% (5m/24h), +30% (1m/24h) as per IEC
Overvoltage
Temperature -250C to +550C -250C to +550C -250C to +550C -400C to +650C -50C to +550C -250C to +650C
Max. switching
5000 7500 8000 15000 10000 20000
Operations/cycle
Life (at 55°C) 100000 hrs 150000 hrs 150000 hrs 200000 hrs 200000 hrs 3,00,000 hrs
Capacitor Switching Devices
Capacitor duty contactor – AC 6b duty
Problem: High Inrush currents Completely shrouded
Separate termination of Damping resistor
Safety & Aesthetic Appeal
Ease of wiring & Enhanced Operational Reliability
Encapsulated resistor assembly
Product Safety
Contactor ON-
OFF indicator
on top
Applications: Slow load fluctuations
Ex: Induction Motors
Capacitor Switching Devices
High PIV
Thyristor switching module for dynamic switching 2.2 kV
Lower Fast
losses response
per kVAr (5 ms)
Auto- No
thermal moving
cut-off parts
No aux
No noise supply
needed
Applications: High load fluctuations
EX: Welding, Elevators & Cranes etc
Detuned Reactors
Copper/
Aluminum
wound Tuning
7% 14%
reactors Factor
Class H
insulation Low Noise Tuning
189 Hz 133 Hz
up to 180˚C Frequency
Application 5th harmonic 3rd harmonic
(Harmonic (250 Hz) and (150 Hz) and
Orders) above above
6 Pulse Drive
High (AC/DC), 3 Single Phase
High Typical Loads phase UPS, UPS, CFL
linearity
Q factor 1.8 In Frequency lamps, Dimmers
Converters
kVAr Ratings
1 to 100 kVAr
(440 V)
Very low
Auto-thermal operating losses Capacitor
cut-off 480 / 525 V 525 V
3 - 5 W / kVAr Voltage
Specialised solution for High Voltage Harmonics
Problems with regular detuned reactors when VTHD is high (>5%)
• Over-heating (>100⁰ C) and burn
• Makes humming noise due to saturation at high VTHD%
• If bypassed, capacitors will amplify harmonics significantly
Special High V-THD withstand reactors TRIED
&
TESTED
• Ensures safer temperature (~58⁰ C)
• Lower power loss and doesn’t saturate
• Mitigates significant current harmonic amplification
• Avoids capacitor over-loading
• Relatively lesser cost of Hybrid solution, as it reduces AHF rating to be selected
Case study at an industry with High Voltage Harmonics
Load current ~1400 Amps
High V-THD reactor installed : 500 kVAr
AHF installed : 300 A ACTUAL SITE
DATA
With Capacitor With regular 7% With high High V-THD
Parameter
Only reactor V-THD reactor reactor + AHF
Voltage Harmonics 13.5 % 12.5% 8% 7.2%
Total Current Harmonics 84.8% 70.9% 21% 5%
Current drawn by 25 kVAr
capacitor 43 A 40 A 32.7 A 31.6 A
(rated : 31 A @416 V)
Reactor Temperature - ~98 ̊ C ~58 ̊ C 55 C
̊
APFC Controllers
Solar Installations
Parameters etaUltra (8R, 16R, 8T, 14 T, 8T + 8R)
Display type 16 x 2 Character LCD
PF display Upto 3 Decimals +kVAr
import
Three phase sensing
CT Sensing Maintains close to unity PF even in II I
-kW +kW
Unbalanced loads
CT Secondary 1A/ 5A Export import
II IV
Auxiliary Voltage 85 – 300 V AC/ DC I
Voltage Sensing
50 – 760 VAC -kVAr
Range Export
Dual Power Factor
Yes (EB & DG)
setting
Individual Harmonics Up tp 31st level KW Import/ Export
4
Sensing at MV Side Yes
Quadrant
Communication Inbuilt RS -485
Availability of 16
sensing
steps
Yes APFC
Cascading Up to 64 steps (16 * 4) controller
For a mix of Stable & Fluctuating loads
Dual PF Controller
etaUltra 8T + 8R for controlling switching of Contactor as well as Thyristor in APFC
Panels
800
Typical Load variation
700
Fluctuating Load
600
500
400
300
Base Load
200
100
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210
At sites with Dual Transformers
APFC panels for Transformer redundancy w/o summation
CTs
Comparison with other type solutions
• Always consider a solution with low life cycle cost!
• IGBT devices are with high maintenance cost & need dust free environment
• All IGBT based devices’ power loss: 22 watts per ampere
• Detuned filters’ power loss: just 4 to 5 watts per ampere
• Now it is easy to workout the running cost of both devices…
• Always use detuned filters for PF correction and control harmonic amplification & use AHF to bring down the residual harmonics
APFC with
Detuned Reactor APFC
APFC with Capacitors +
APFC with
Detuned Reactors &
only
along with AHF
Capacitors Switching devices
Capacitors - a combination of =
Contactor – HYBRID
Thyristor Modules
Quick Summary
V-THD I-THD Solution for unity PF and Harmonic levels below IEEE limits
Low Low APFC panel with only capacitors
Step 1 :APFC panel with regular detuned reactors
Step 2 : Conduct Power Quality study and install AHF
Low High
Or
Hybrid filter
Step 1 : APFC panel with High V-THD detuned reactors.
Step 2 : Conduct Power Quality study and install AHF
Or
High (>5%) High
Hybrid filter with High V-THD detuned reactors
Note : Grid distortion cannot be controlled
EtaHarmonic V 2.0 – Harmonic estimation tool
• For Green field projects, we can help consultants in sizing of Active Filters based on the load data during design stages.
• Loads considered – VFDs (6 Pulse & 12 Pulse, with & without choke), UPS, LEDs, Computers.
