System Impact Studies
 
FACTS and HVDC Application Studies 
Topics: ​Focus: Recommendations:
Type of enhancement (such as SVC,
Mechanically Switched Capacitors (MSC), STATCOM and/or HVDC), voltage/bus location
for enhancement, enhancement rating, stability controls, modeling, interactions, operations
and controls, transients, harmonic sectors, performance for prespecification, pre-manufacturing and verification needs 
 
Overall power system with enhancement
specifics for equipment such as SVC, STATCOM, MSC, shunt/series compensation, HVDC, lines, cables, transformers



Individual device specification, location, rating, evaluation and optimization for steady-state, contingency and disturbance conditions




 
 
 
Black Start, Transformer, and Motor Starting Studies
Topics: ​Focus: ​Recommendations:
System restoration, motor stalling, islanding, overvoltages, inrush currents, reactive/real
power capability, motor starting currents, load factors, voltage dips, resonance, harmonics, unidirectional components

 
Black start generator, thermal plant, motors, loads, interconnecting circuits, circuit breakers, relays and protection, transformers



Updated procedures for black start such as: equipment specification for motors/generators and/or relay and protection, application of pre-insertion resistors,  synchronous switching, reactive compensation, reduced-voltage start, surge arresters, and/or surge capacitors
 
 
Load Flow and Stability Studies
Load flow and stability analysis is conducted to evaluate a power system’s performance during normal and contingency conditions to aid in transmission system expansion planning as well as determine the best operation of an existing system. 
 
Studies pertaining to generation interconnection include: (1) voltage and thermal steady-state analysis, quantifying the impact of generator connections on the path flow ratings of the system and the power flow requirements to meet the voltage and thermal limits of the system, and (2) transient stability analysis, examining generator and system response during a system disturbance with respect to utility criteria, regional criteria, and instability concerns with new generation online.
 
Additional stability studies include static var compensator (SVC) and high voltage direct current (HVDC) application analysis (pre- and post-system evaluation), and the interaction of reactive devices with neighboring generating stations.
 
 
Generation Interconnection Studies 
Topics: Focus: Recommendations:
Voltage and thermal violations, transient
stability, short-circuit duties, interconnection requirements





Generation characteristics, renewable resource characteristics, circuit breakers, lines, cables, transformers, series capacitors, shunt
capacitors, series reactors, shunt reactors, load characteristics, and overall power system with enhancement specifics for SVC, STATCOM, and
MSC

Reactive compensation (such as SVC, STATCOM, and MSC), series compensation, additional infrastructure evaluation (such as lines and transformers), and review of system operating procedures and system protection (fault clearing times and schemes, load dropping, generator dispatch, special protection schemes)

Renewable Resource Integration Studies 
Topics: Focus: Recommendations:
Thermal and voltage violations, transient
stability, reactive power compensation, voltage flicker, power quality, resonance, harmonics, system transients, short-circuit, operational requirements, assessment of interconnection requirements

 
Renewable resource characteristics, circuit breakers, lines, cables, transformers, series capacitors, shunt capacitors, series reactors, shunt reactors, overall power system with enhancement specifics for equipment such as
SVC, STATCOM, and MSC

Reactive compensation (such as SVC, STATCOM, and MSC), series compensation, additional infrastructure evaluation (such as lines and transformers), and review of system operating procedures and system protection (fault clearing times and schemes, load dropping, generator dispatch, special protection schemes)
 
Reactive Power Assessment Studies 
Topics: Focus: Recommendations:
Retirement of thermal generation, retirement
of once-through cooling units, retirement of synchronous condensers, infrastructure augmentation, integration of renewable
resources with concerns such as thermal and voltage violations, transient stability, reactive power compensation, voltage flicker, power quality, harmonics, interconnection
requirements
Overall power system with enhancement
specifics for SVC, STATCOM, and MSC, series capacitors, shunt capacitors, series reactors, shunt reactors, load characteristics, generation characteristics, renewable resource characteristics, circuit breakers, lines, cables, transformers


 
Reactive compensation (such as SVC, STATCOM, and MSC), series compensation, additional infrastructure evaluation (such as lines and transformers), review of system operating procedures and system protection (fault clearing times and schemes, load dropping, generator dispatch, and special protection schemes)


 
 
Power System Stability Analysis 
Topics: Focus: Recommendations:
Dynamic (including transient, oscillatory,
and/or rotor angle) stability, power system oscillations

Representation of large portions of the power system with a focus on component and detailed load modeling

ReactiveShunt/series compensation, power flow control/limiting devices, FACTS controllers, generator controls, supplemental power system oscillation damping controls
 
Power Flow Thermal and Voltage Stability Analysis
Topics: Focus: Recommendations:
Power-voltage (P-V) relationship,
voltage-reactive power (V-Q) relationship,
thermal limitations, voltage violations, power
flow control and/or limiting, device/equipment ratings
 

Representation of large portions of the power system



 
Shunt/series compensation, power flow control/limiting devices, equipment dynamic ratings, FACTS controllers, generator controls


 
 
 
Electromagnetic Transient Studies
Power system transients analysis for transmission and distribution systems is an integral part of pre-specification analysis, operation and maintenance practices, root cause analysis, and system planning for equipment.  Energizing transients are becoming increasingly more important with the growing number of shunt and series reactive device installations in power systems.  This is because reactive device switching is one of the most frequent utility operations, potentially occurring multiple times per day and hundreds of time per year throughout the system, depending on the need for system voltage/var support.  There are a number of important concerns to be aware of when these devices are energized at the transmission system voltage level.
 
 
Transient Recovery Voltage Studies
Topics: Focus: Recommendations:
Transient recovery voltages (TRV) caused by
short-line faults (SLF), terminal faults, series reactor-limited faults, transformer-limited
faults, series capacitors, shunt reactor
switching

Representation of local bus in the power
system with a focus on component modeling for high frequencies (e.g., microsecond timeframe) where voltages are driven by equipment inductances, stray capacitances, and high-frequency resistive losses
Addition of capacitance line-to-ground, modification of breaker characteristics, up-rating of circuit breaker, surge arresters, synchronous opening control


 
Transmission Project and Harmonic Studies
Topics: Focus: Recommendations:
Temporary overvoltages, switching
overvoltages, insulation coordination,
transient recovery voltages, harmonic shifts, frequency-impedance (f-z) characteristics, increased X/R ratios, lightning overvoltages, transformer saturation, ferroresonance,  Subsynchronous Resonance (SSR) evaluation [including Torsional Interaction (TI), Torsional Amplification (TA), and Induction Generator
Effect (IGE)]
 
Circuit breakers, surge arresters, transmission lines, cables, transformers, Phase Angle
Regulators (PARs), opening/closing resistors, series/shunt reactors, series/shunt capacitors, generation, load, FACTS controllers




Switching/operating restrictions, filters, capacitor bank augmentation, line augmentation, surge arresters, opening/closing resistors, synchronous switching, series/shunt reactors, TRV control capacitors, ferroresonance suppression devices, modification to system operating procedures, grounding practices


 
    
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