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January 2019 IEEE The Increasing Application of FACTS
January 2019IEEE
The Increasing Application of FACTS
Proprietary and Confidential
Power System Constraints Steady State Power Transfer Limits
Voltage Stability Limit
Dynamic Voltage Limit
Transient Stability Limit
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Power System Constraints Power Oscillation Damping Limit
Inadvertent Loop Flow
Thermal Limit
Short Circuit Limit
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Conventional Solution Switched Shunt
Transformer LTC
Phase Shifting Transformer
Others- Include re-conductoring, new line etc.
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FACTS What are FACTS?
– Flexible AC Transmission Systems
– Enhances the transmission network by increasing the use of their capacity
– Fast Operating Controllers which enhances the safe operating limits of the transmission system without risking stability
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Power Flow
Changing the above parameters will result in increase in power flow through the existing system
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FACT Devices Different types of FACT Devices:
– Fixed Series Capacitor
– Thyristor Controlled Series Capacitor (TCSC)
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FACT Devices– Static Var Compensator (SVC)
– Static Synchronous Compensator (STATCOM)
– Static Synchronous Series Compensator (SSSC)
– Unified Power Flow Controller (UPFC)
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Advantages of FACTS Increase/Control of power transmission capacity in line
Improvement of transient stability limits
Enhancement of System Damping
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Advantages of FACTS Limiting Short Circuit Currents
Alleviation of Voltage Stability
Power Factor Improvement
Renewable Power Integration into the Grid
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Series Capacitors Connected in series with line
Used to reduce the effective impedance of the line
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Series Capacitors
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Series Capacitors
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Series Capacitors
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Series Capacitors
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Application of FSC Enhanced base power flow and loadability of the series-
compensated line
Reduces the effective impedance of the transmission line and improves load sharing
Economical Solution and widely used
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Application of FSC Smaller kvar and kV ratings required for providing same
compensation as shunt devices
Reactive power regulation
Angular stability
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Limitation Sub-synchronous Interaction
Fixed impedance- No controllability of the impedance/ power flow
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TCSC A fixed series compensation module as described in the
previous section
A module consisting of the series capacitor in parallel with a thyristor controlled air core reactor
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TCSC When Thyristor is blocked, it is an FSC
When Thyristor is in full conduction, Cap bank is effectively bypassed
Between blocked and full conduction, it is possible to smoothly vary the TCSC impedance.
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TCSC
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Application of TCSC Rapid Continuous control of the transmission line series
compensation level
Dynamic Control of power flow in selected transmission lines which enables optimal power- flow conditions and prevent the loop flow of power
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Application of TCSC Damping of power swings from local and inter- area oscillations
Suppression of sub synchronous oscillation.
Decreasing dc-offset voltage resulting from insertion of series capacitor
Quick insertion and bypass of series capacitors
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Application of TCSC Voltage Support and alleviation of voltage instability
Reduction of short-circuit current
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SVC Introduction SVC is Static Var Compensator
SVCs are meant to provide dynamic Voltage support (fast response)
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SVC Introduction SVC can have following configurations:
– MSC-TCR
– TCR- FC
– TCR-FC-MSC
– TCR-FC-TSC
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TCR
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Harmonics Generated by TCR
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Harmonics Generated by TCR
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SVC Applications Power Factor Improvement
Voltage Control or low voltage issue
Reactive Power Compensation
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SVC Applications Flicker Improvement
Harmonic Improvement
Power Oscillation Damping
Increase Power Transfer Capability
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SVC Applications
Improve steady-state and dynamic stability of the grid with fast response time
No short circuit contribution
Negative sequence control (system unbalance)
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SVC Applications Reactive Margin Improvement
– PV and QV Margin Improvement
Induction Motor load area where voltage recovery will be an issue
Arc Furnace/Welding- Industrial Load
Widely used and several installations across globe
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Limitations Harmonic Source
Response time in several 10s of milliseconds
Performance in the under-voltage conditions
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Limitations Layout or footprint
Limited Flicker improvement compared to STATCOM
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STATCOM STATCOM – Static Synchronous Compensator
– Shunt Connected reactive power compensation device
– Voltage Source Converter, from a given DC voltage, produces a set of 3-phase ac-output voltages, each in phase and coupled to corresponding AC system through an interface inductance or interface transformer.
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STATCOM– DC Voltage is provided by an energy-storage capacitor
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STATCOM
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STATCOM
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SVC vs STATCOM
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Advantage of STATCOM over SVC STATCOM can be used for the same applications as SVC
STATCOM has the following advantage over SVC
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Advantage of STATCOM over SVC Smaller Foot print
Generate no or minimal harmonics
Better Flicker mitigation than SVC
Faster response time
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Advantage of STATCOM over SVC Can limit transient/switching overvoltage
Compensation for DC transmission LCC especially when short circuit capacity is too low
Relocatable
Superior performance during undervoltage condition
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Advantage of STATCOM over SVC Can be interfaced with battery and used as dynamic energy
storage device– Black Start
– Wind Farm Storage
– Delay in building new distribution lines
– Rapid power schedule changes
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Summary TableIssue Device
Steady State Voltage Control
SVC
STATCOM
Dynamic and post- contingency voltage control
SVC
STATCOM
Improvement of steady state load sharing FSC
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Issue Device
Transient Stability Improvement
FSCSVC
STATCOM
Power Oscillation DampingSVCTCSC
Power Quality ImprovementSVC
STATCOMSub-synchronous reasonance
mitigationTCSCLoop flow mitigation
Summary Table
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Other FACT Devices SSSC- Static Synchronous Series Compensator
– VSC connected in series
– Controls Power flow
– Provides series compensation
– Avoids SSR
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Other FACT Devices Unified Power Flow Controller (UPFC)
– VSCs connected in series and parallel
– Encompasses all capabilities of voltage regulation, series compensation and phase shifting
– Provides independent control of both real and reactive flow (extremely fast)
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Thank You!For inquiries, contact:
Kalyan ChilukuriPower Networks [email protected]
