medium voltage real time & transient free capacitor systems

Medium Voltage Real Time & Transient Free Capacitor Systems

Division - Name - Date - Language 2

Outline

Introduction Why RTRC or TFRC? Limitations of Conventional Solutions The RTRC and TFRC Solution Applications Benefits Product Characteristics


Capacitor Offering Schneider Electric is the world’s largest LV capacitor

manufacturer by market share Power Quality Correction Group (PQc) located in

Toronto, Canada has marketing, sales, application engineering, design and technical support responsibility for North America

Low Voltage Equipment is manufactured at the Waterman facility

Medium Voltage Equipment is assembled at Square D facility outside of Cincinnati


Capacitor Offering Fixed Capacitors Standard Automatic Capacitor Banks Anti-Resonant Automatic Capacitor Banks Filtered Automatic Capacitor Banks Real Time Reactive Compensation Systems Transient Free Reactive Compensation

Systems MV Metal Enclosed Systems MV Real Time & Transient Free Systems


Service OfferingOn-site measurementComputer Network

SimulationsAnalysis of ProblemReportSpecificationsCustom Engineered

EquipmentCommissioningVerification of

PerformanceTrainingAfter Sale Servicing

Solution Cycle

Measure

Simulate

Analyze & Report

Specify & Propose

Commission


Power Factor

Ratio of Active (Real) Power to Total (Apparent) Power (kW/kVA)

A measure of efficiencyDepends on the phase angle between

voltage and current waveforms


Power Factor DefinedReactive

Power develops the magnetic field required by machines to perform useful work


Power Factor FundamentalsIn this example,

demand was reduced to 8 250 kVA from 10 000 kVA.

The power factor was improved from 80% to 97%

Before After


Increased System Capacity

Apparent Power2500 KVA

Real Power1500 KW

Reactive Power2000 kVARUncompensated

cos 1 = .60cos 2 = .882

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2

1700 KVAReactive Power800 kVARCompensated

Any capacitor based system reduces apparent power (KVA) and load current

Potential savings in capital investment

Alternately, additional load can be added to the network without the risk of overload


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HarmonicsCurrent Limiting Reactors in

multi-step MV standard systems limit capacitor inrush currents

Air or Iron Core reactors in MV Anti-Resonant and Filtered systems detune the system to prevent resonance and remove up to 50% of the 5th harmonic


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Harmonic Current Waveform(Typical 6 Pulse Drive)


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Resonance

The installation of standard capacitors can magnify harmonic currents on the network


3

Resonance

Magnification of Harmonic Current when Standard Capacitors are Added to the Network

Resonant Point likely to amplify dominant harmonic (typically 5th)


4

Detune to Avoid Resonance

Effect on Harmonic Current when Anti-Resonant Capacitor Bank is Applied

Resonant Point where no Harmonic Content present (3.7th typical)

5th Harmonic on Network is reduced(4.4 Tuning)


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The Real Time ChallengeTo compensate reactive power required by

rapid and frequent load variations

• motivation:

– increased productivity

– elimination of voltage flicker and sags

– increased system capacity and energy efficiency


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Conventional TechnologyCompensates reactive energy of stable loads only

Unable to cope with rapid and frequent load variations

Limited Speed - Why?

To reduce wear of vacuum switchesTo allow capacitors to discharge before reconnectionConventional Controller speed limitation


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Conventional Switch Structure

HRC Fuses

VacuumContactors

OptionalDe-tunedInductor

L1 L2 L3Vacuum (or SF6)contactors or breakers are used to connect a capacitor group.


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Real TimeReactive Compensation

One cycle (17 ms) or less response to load fluctuations

Transient Free Connection of Capacitors

Minimal wear of electronic switching elements


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Transient Free Reactive Compensation

3-4 second response to load fluctuations

Transient Free Connection of Capacitors

Minimal wear of electronic switching elements


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Electronic Switch Structure

Fuses

SCR-Diode

De-tunedInductor

L1 L2 L3


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Transient Free Switching

RTRC - Smooth Connection

Current inrush with vacuum switching can be 15 - 20 times steady state current

Resultant voltage transient can effect sensitive electronics

RTRC and TFRC systems generate no network voltage transient


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RT Acquisition & Response

Acquisition Time 17 ms

A

B

RTRC Bank Current

System Voltage

Load Current V


3

End Result Any variation in reactive power is

compensated within one cycle (16.7 ms) using transient free switching of capacitor stages resulting in:

•increased productivity

•elimination of voltage flicker & sags

•increased system capacity & energy efficiency


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Real Time ApplicationsUnstable Loads (rapid changes):

•Injection molding machines•Elevators•Presses•Rock Crushers

Motor Starting•compensation of inrush current for many motors•allows normal starting torque

Spot Welding (typically at low voltage)extremely fast changes - less than one

second (typically at low voltage)•Re-enforced Mesh for concrete•Automotive industry

•Wood Chippers•Mining Conveyors•Induction Heat Treating•DC Hoisting


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Results of RTRC Installation• Gas Pumping Station in Colorado

• 25 KV Line to 2.5 MVA Transformer step down to 2.4 KV

• Three FVNR Motors (500 HP, 700 HP, 700 HP)

• Motor start causing unacceptable voltage drop on 25 KV line (16-18%)


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• Solution was a 3.6 MVAR, 2.4 KV Real Time System

• Three equal steps of 1.2 MVAR each

• Utilized air cooled SCR/Diode modules

• Installed outdoors

• Goal to obtain less than 5% voltage drop on the 25 KV line

Results of RTRC Installation


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Results of RTRC Installation500 HP & 700 HP Running

Starting 2nd 700 HP Motor


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Objective to limit voltage drop to less than 5% on the 25 KV line has been met

• initial voltage drop is only 4.2% on the 2.4 KV line• secondary voltage drop of 7.3% at 2.4 KV line (as stages turn off)

– modifications to the control will improve this further

Motors previously took 4-6 seconds to come up to speed

• with RTRC, motors are up to speed in less than 2 seconds

Results of RTRC Installation


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Transient Free ApplicationsSensitive Networks

Hospitals Data Processing Centers Microelectronics Fab Facilities Pharmaceutical Facilities Airports Research laboratories Other Industrial and commercial facilities with high concentrations of sensitive electronic loads


0

Voltage Sag and Flicker Reduction

With

•Voltage sag is reduced as a result of reactive compensation during the load fluctuation.

•The voltage sag during is affected more by the power factor than by current amplitude reduction.

VVS

VL

Without

V

VS

VL

With


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Energy SavingsEnergy saving due to reduction of losses and harmonics:

Losses in cables:

• Copper losses - I2R.

• Skin effect losses due to reduction of harmonics.

Losses in transformers:

• Copper losses - I2R.

• Skin effect losses due to reduction of harmonics.

• Iron losses due to reduction of harmonics.

Total estimated saving: 3 - 5%


2

RTRC Advantages Flicker Reduction

Compliance with flicker standards

Network Stabilization and reduced equipment outages

Voltage Regulation Improvement Reduced duty on tap changers

Improved Network Utilization Reduced Transformer loading

Current reduction on Bus Bars, Breakers and Cables

Energy Saving, Power Factor Correction & Harmonic Reduction


3

Process Productivity Improvements

The RTRC will eliminate:failed motor starts due to voltage sagsundervoltage tripping of sensitive loadslighting flicker and HID lighting shutdownoverloaded distribution equipmentcapacitor switching transients


4

RTRC SummaryADVANTAGES

•Increases network capacity•Minimizes voltage sags•Minimizes voltage flicker•Reduces load current•Avoids wear of vacuum

contactors & capacitors•Transient free switching in

sensitive networks•Avoids use of reduced voltage

starters•Saves energy and improves

Power Factor

DISADVANTAGES•Costly solution

compared to standard capacitor systems (but often the only viable solution)

•Physical space requirements


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MV RT & TF Product Overview

Metal Enclosed Systems up to 15 kV

Three-Bushing, delta capacitor units available up to 5 kV. Two-bushing capacitors connected in Delta for higher voltages

Type 1 indoor or Type 3R outdoor enclosure types.


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Real Time Reactive Compensation Systems MV9000 Series Power Factor Correction of

highly cyclical loads

Transient Free Reactive Compensation Systems

MT6000 Series Power Factor Correction of

networks with sensitive electronic loads


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Standard, Detuned or Filtered? MT6000 & MV9000 are typically Anti-resonant

or filtered but may also be standard with current limiting reactors only

Filtered used for Power Factor Correction of networks with more than 50% Non-Linear Loads

Anti-resonant and filtered systems are manufactured with higher than nominal voltage capacitor elements to ensure long term system stability.


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Status Indicators

Readings Display

Function Keys Description

Function Keys

Controller


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Protection Unbalance and Overload protection via

phase current sensing standard for either wye or delta capacitor steps

Optional unbalance protection by neutral current sensing on wye connected capacitor steps

Optional Neutral to Ground Potential transformer for unbalance protection for wye connected banks


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Capacitors

Merlin Gerin PROPIVAR or Cooper (McGraw Edison)

External Fusing Standard


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Merlin Gerin Capacitors Available as

Three Phase, Three-Bushing Delta Connected, up to 5 kV or Single Phase, Two-Bushing for voltages higher than 5 kV


2

Merlin Gerin Capacitors

Environmentally safe biodegradable non PCB dielectric liquid

Good Heat Dissipation and Low dielectric losses result in long element life


3


High Overvoltage and Overcurrent withstand:

• 10% Overvoltage for 12 hours a day

• 30% Continuous Overcurrent Highly resistant to transient

overvoltages and partial discharge levels


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Suitable for harmonic filtering applications and networks with poor voltage regulation


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Cooper Capacitors Single Phase, Two-Bushing for

Wye or Delta connection 125% Continuous rms Overvoltage

withstand and 135% peak overvoltage capability

Wide operating temperature range:• -40 to 131ºF (-40 to 55ºC)

Environmentally acceptable dielectric fluid


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Cooper Capacitors

Standard unit power rating from 50 to 400 kVAR single phase from 2.4kV


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Current Limiting Fuses

To protect capacitors, fuses are rated as closely as possible to the capacitor steady state current

Blown fuse indication directly on the fuse (pop-up indicators)

Visible via viewing windows in enclosure


8

Conventional Switching Stage

Three Phase Reactor

Capacitors

Current Transformers for unbalance detection

Vacuum Contactor


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Electronic Switching Modules Switching two phases with

Delta connected capacitors Air or Liquid Cooled Stick

Stacks of anti-polar SCR/Diodes with failsafe cooling systems

•temperature, air flow, pressure monitoring

Multiple modules connected in series for higher voltagesLiquid Cooled Stick Stack


0

HVL Interrupter Switch

Direct Drive Operator Fused for short circuit

protection or Unfused available

Load Break to max 2400 kVAR @ 5 kV or 15 kV


1

Iron Core Reactors

Necessary to Detune network to prevent resonance when large harmonic producing loads are present

Reactors Filter dominant harmonic (usually the 5th)


2

Iron Core Reactors Single or Three phase

laminated low hysteresis reactors with precision air gap

All copper windings, mounted on insulated bushings up to 95 kV BIL

Current Limiting Reactors in standard systems are Air or Iron Core


3

Enclosure

Modular Style Design either indoor NEMA 1 or outdoor NEMA 3R (others available)

All Silver-Flashed Copper Bus

• Better fault withstand ratings (50kA IC standard)


4

Enclosure Removable Panels over bolted

steel frame

• Rigid construction while allowing ease of servicing

Standard ASA49 Gray paint finish. Other finishes available upon request.


5

Enclosure Key interlocks standard

• Electrical interlocks standard Tamper resistant interlocked

ground switch for each capacitor stage

Viewing windows to ensure ground switch and main switch operation


6

Enclosure Control Cabinet mounted rear or

side of main (remote mounting optional)

Optional thermostatically controlled, ball bearing fans

Welded lifting eyes Three point door latch


7Division - Na me - Da te - Lan gua ge 20 © 2001 Schneider Electric Canada, All Rights Reserved June, 2001

Schneider Electric Canada Inc.19 Waterman AvenueToronto, Ontario, M4B 1Y2www.schneider-electric.caTel.: (416) 752-8020Fax: (416) 752-6230

Schneider ElectricPower Quality Correction Group255 Orenda RoadBramalea, Ontario, L6T 1E6www.reactivar.comTel.: (905) 459-8805Fax: (905) 454-3603

medium voltage real time & transient free capacitor systems

Documents

date language

harmonic slide

network slide

cincinnati slide

commission slide

pulse drive slide

useful work slide

risk of overload slide