Contingency Analysis

The new Contingency Analysis tool in DIgSILENT PowerFactory has been
designed to offer a high degree of flexibility in configuration,
calculation methods and reporting options. Single- and multiple-
time-phase contingency analyses are available, both of which offer
automatic or user-defined contingency creation based on events, and the
consideration of controller time constants and thermal (short-term)

Calculation Options for Contingency Analysis:

Support of three calculation methods:

  • AC load flow calculation
  • DC load flow calculation
  • Combined DC/AC calculation; i.e. full DC load flow calculation and automatic recalculation of
    critical contingencies by AC load flow

Single- and Multiple- Time-Phase calculations. Multiple time-phase
contingency analysis facilitates user-defined post-fault actions within
discrete time periods.

Generator Effectiveness and Quad Booster Effectiveness calculation:

This calculation feature assists the planner in defining appropriate
measures for overstressed components in critical contingency cases:
During contingency analysis, the possible impact of individual generator
re-dispatch or transformer tap changes on overstressed lines is
evaluated. Corresponding reports are available that list the generator
and quad booster effectiveness on a per-case basis.

Ultimate Performance via Grid Computing: Possibility to perform
the contingency analysis calculation in parallel (on multi-core machines
and/or clustered PCs)

Management of Contingencies/Fault Cases:

User-friendly definition of contingencies (n-1, n-2, n-k, busbar)
as ‘Fault Cases’ supporting user-defined events to model post-fault
actions (re-switching, re-dispatching, tap adjustment, load shedding)

Clustering of ‘Fault Cases’ into ‘Fault Groups’ for efficient data management

Special Operational Libraries to manage ‘Fault Cases’ and ‘Fault Groups’ for future re-use

Automatic creation of contingency cases based on Fault Cases, considering current network topology

Result File Management:

Recording of results in (sparse) result file; accessible for any kind of export and/or customer-specific post-processing

Predefined and user-definable monitoring lists for recording of
results; selection of individual components, component classes and their
associated variables to be recorded. Any available calculation result
for a standard load flow calculation is accessible during contingency

User-defined limits for recording of results (thermal loadings, voltage limits, voltage step change)


A wide range of standard reports is available, facilitating summary
views or the presentation of results on a per-contingency basis:

Maximum Loadings Report

Loading Violations (per case) Report

Voltage Ranges Report

Voltage Violations (per case) Report

Generator and Quad Booster Effectiveness Report

Other key features:

Tracing Facilities: Use of the new ‘Trace’ function to step
through events in a multiple time-phase contingency, while viewing
updated results in the single-line graphic

Support of component-wise Short-Term Ratings based on pre-fault loading and post-fault time

Special “Contingency Analysis” toolbar for user-friendly configuration, calculation and reporting

Parallel Computing Option:

Calculation of contingencies in parallel represents an important required computation time reduction depending on the number of cores being used.

Management of the parallel computation function

Dedicated settings for the execution of the contingency analysis

Quasi Dynamic Simulation

Power Factory offers the execution of medium to long term simulations thanks to the new Quasi Dynamic Simulation engine. If simulation periods ranging from hours up to years are under investigation, the Quasi Dynamic Simulation automates the entire simulation process. Multiple load flow calculations are carried out with user-defined time step sizes between each simulation. The results from each calculation are stored and are available for post processing. The tool is particularly suitable for planning studies in which long term load and generation profiles are defined in parallel with multiple contingency scenarios, variations and expansion stages. In terms of user handling, the tool is easy to use.

Additional features:

  • All load flow calculation variabes are available for storing and plotting
  • Statistical data for the variables
  • Results such as maximum, minimum, average, variance, etc. are provided
  • Energy estimation for the studied time interval
  • Tabular reports for the most relevant results as loading/voltage ranges and non-convergency cases
  • Export to HTML or Excel options

Network Reduction

The typical application of the network reduction tool is a project where
a specific network has to be analyzed but cannot be studied
independently of a neighbouring network of the same or of a higher or
lower voltage level. In this case, one option is to model both networks
in detail for the calculation. However, there may be situations in which
it is not desirable to perform studies with the complete model; for
example when the calculation time would increase significantly, or when
the data of the neighbouring network is confidential. In such cases it
is good practise to provide a representation of the neighbouring network
which contains the interface nodes (connection points) which may be
connected by equivalent impedances and voltage sources.

The objective of Network Reduction is to calculate the parameters of a
reduced AC equivalent of part of a network, as defined by a boundary.
This boundary must completely split the network into two parts. The
equivalent network is valid for both load flow and short-circuit
calculations. ,Following this, a model variation can be optionally
created in the PowerFactory database, whereby the full representation of
the portion of network that has been reduced is replaced by the

General Features
  • Flexible definition and maintenance of network boundaries with Boundary Definition Tool. Various
    features such as colouring of boundaries and topological checks
  • Network Reduction can be calculated at any appropriate boundary
  • Support of load, standard Ward (PQ-equivalent), extended Ward (PV-equivalent) and REI-DIMO equivalents
  • Support of short-circuit equivalents for transient, subtransient, peak-make and peak-break currents
  • The reduced network can be created in a network variation. This
    allows for simple comparison and swapping between reduced and
    non-reduced cases.
  • Robust reduction algorithms based on the sensitivity approach,
    i.e. reduced network matches for the current operating point as well as
    for network sensitivities
  • Implicit result verification feature

Protection Functions

The basic functional model library of DIgSILENT PowerFactory’s
protection analysis tool has been extended to include additional devices
such as CTs, VTs, relays, fuses and more complex protection schemes
including user-defined modelling capabilities. Additionally, there are
specially designed interactive VIs (Virtual Instruments) for displaying
system quantities and, more importantly, for modifying protection
settings in the graphical environment. This last feature is especially
useful, as coordinated settings between different protection schemes can
be modified via the cursor in the graphical environment, following
which the settings in both the database and the simulation environment
are also updated.

All protective devices are fully-functional under steady-state and
transient conditions, allowing device response assessment under all
possible simulation modes, including load flow calculation, fault
analysis, RMS and Instantaneous Values (EMT) simulation.

PowerFactory’s main protection features are:
  • Accurate steady-state relay checking via short-circuit and load flow (balanced & unbalanced)
  • Precise dynamic relay checking with RMS and EMT simulations
  • Consideration of current transformer saturation
  • Diagrams for overcurrent and distance coordination:
    • Time-overcurrent diagrams
    • R-X characteristic diagrams
    • Time distance diagrams
  • Automatic Protection Coordination Wizard for time-overcurrent protection schemes
  • Short-circuit trace to examine the performance of a protection scheme in response to a fault or combination of faults
Protection Model Library and Functionality

The DIgSILENT PowerFactory protection analysis tool contains a
comprehensive protection device model library. All relays are modelled
for steady-state calculations (short-circuit, load flow), RMS and EMT
simulation modes. The definition of relay types is highly flexible via
block diagrams. For RMS and EMT simulation purposes, relays may be
extended and adopted to cope with user specific requirements via the
PowerFactory DSL language The features of the protection model library
are listed below.

Fuses are represented by their melting curves. It is possible to take minimum and maximum melting curves into account.

Time-Overcurrent Relays for 1-phase, 3-phase, ground and negative
sequence time over-currents. Additionally, the relay characteristics
can incorporate the following standards and solution methods:

  • IEC 255-3, ANSI/IEEE and ANSI/IEEE squared
  • ABB/Westinghouse CO (Mdar)
  • Linear approximation, Hermite-spline approximation
  • Analytical expressions via built-in formula editor and analyser (DSL)

Instantaneous Overcurrent Relays for 1- phase, 3-phase, ground and negative sequence time over-currents.

Directional Relays for overcurrent, power, ground current, and
any combination of time and instantaneous overcurrent relays.
Additionally, voltage and current polarization is used for the detection
of negative and zero sequence components considering also dual
polarization. Optional: with voltage memory.

Distance Relays for phase, ground and zone distance protection.
Provision is available for incorporating overcurrent and under-impedance
starting units (U-I or Z) as well as angle under-impedance.

Different characteristics are available for distance relay zones including:

  • MHO, offset MHO
  • Polygonal, offset polygonal
  • Tomatoes, lens and circle
  • R/X Blinders and quadrilateral

Support of various polarisations such as:

  • Self-polarised
  • Cross polarised (90ø connection)
  • Positive, negative sequence polarised
  • Optional: voltage memory

Zero sequence and parallel line compensation

Voltage Relays for under-voltage, instantaneous voltage, voltage balance and unbalance.

Additional devices such as: Breaker Fail, Motor Protection, Generator
Protection, Differential Protection, Reclosing Relays, Low Voltage
Circuit Breakers, and Out-of-Step Relays.

In addition to these protection functions and relays, DIgSILENT
PowerFactory provides further devices and characteristics for more
detailed protection system modelling, such as:

  • Current and voltage transformers that include saturation effects
  • Conductor, cable damage curves, cable overload curves and inrush peak current modelling
  • Transformer damage curves (ANSI/IEEE Standard C57.109-1985) and inrush peak current modelling
  • Motor starting curves, cold and hot stall, in-rush peak current modelling, and any user-defined curves

All protection device models are implemented within the composite model
frame environment. This allows users to easily design and implement
their own models, by utilising the graphical user interface for
constructing block diagrams.

Output & Graphical Representation
Time-Overcurrent Diagrams
  • Overcurrent curve adjustment using drag & drop
  • Display of tripping curve tolerances during drag & drop
  • User-defined labels
  • Tripping times are automatically displayed for calculated currents in time-overcurrent diagrams
  • Display of an unlimited number of overcurrent curves in diagrams
  • Simple creation and addition of diagrams via single line graphics
  • Display of motor starting curves, conductor/cable and transformer damage curves
  • Balloon help showing name of relay, etc.
  • Double-click on curves to change relay settings
  • Additional axis for voltage levels
  • Display of single line diagram paths in time-overcurrent diagrams
R-X Characteristic Diagrams
  • Display branch impedances with several options
  • Automatic display of calculated impedances
  • Adding relays with offset
  • Flexible display of zones (starting zones, etc.)
Time Distance Diagrams
  • Different methods for calculating curves: kilometrical or short-circuit sweep method
  • Forward and/or reverse diagram
  • Selectivity check of distance and overcurrent relays/fuses in same diagram
  • Separate overreach zone representation
  • Additional axis showing relay locations and busbars/terminals
  • Selectable x-axis scaling (length, impedance, reactance, 1/conductance)
Single Line Diagram
  • Colouring of switches according to relay locations, relay tripping times
  • Display of relay tripping times in result boxes
  • Additional text boxes for relay settings
Relay Setting Report
  • Simplified ASCII reports genertaed in the output window
  • Tabular report command can be customised to deal with the structure of complex relay models and for a protective device class
Relay Tripping Report
Overcurrent-Time Protection

The coordination of overcurrent-time protection is performed graphically
using the current-time diagram as the basis. Relay settings are
modified using drag & drop to move characteristics. Short-circuit
currents calculated by the short-circuit command, are shown in the
diagram as a vertical line. In addition, the corresponding tripping
times of the relays are displayed. Coordination between relays at
different voltage levels is available. Therefore, currents are
automatically based on the leading voltage level, which can be selected
by the user.

Distance Protection

For distance protection coordination, two powerful graphical features
are integrated. The first of these features is the R-X diagram for
displaying the tripping zone of distance relays and the line impedances.
Several relays can be visualised in the same R-X diagram. This can be
useful for the comparison of two relays that are located at different
ends of the same line. The relay characteristics and the impedance
characteristic of the connecting line will be shown in the same R-X
diagram. Following short-circuit calculations, the measured impedances
are visualised with a marker in the shape of a small arrow or cross.
From the location of the marker the user can see the tripped zone and
its associated tripping time. For dynamic simulation, measured
impedances of the relays can be displayed, thereby visualising the
functioning of power swing blocking or out-of-step tripping relays.

The second powerful graphical feature is the time-distance diagram,
which is used for checking the selectivity between relays along a
coordination path. The relays on a coordination path can be displayed in
diagrams for forward, reverse or for both directions. Consequently, it
is very easy to check the selectivity of the relays along a coordination
path. Two different methods for calculation of the tripping curves are
provided. These are the kilometric and the short-circuit method.

  • Kilometric method: The reach of the zones is calculated from the
    intersection of the given positive sequence impedance of the lines, and
    the impedance characteristic of the relays.
  • Short-circuit method: This is the main method for checking the
    selectivity. Short-circuits (user-defined fault type) are calculated
    along the coordination path. The tripping times for the time-distance
    curve are determined using the calculated impedances. The starting
    signal of a relay is also considered.

A special feature of the distance protection is the consideration of
blocking signals or POTT (permissive over-reach transfer tripping), PUTT
(permissive under-reach transfer tripping), which are also taken into
account. In addition to tripping curves of distance relays, the curves
of overcurrent relays can be displayed and coordinated in the same
diagram using the short-circuit method.

Both the kilometric and the short-circuit method consider breaker
opening times in the calculation of tripping times. The breaker opening
time can be optionally ignored.

Coordination Assistant

The coordination assistant helps the protection engineer to quickly find well-structured and consistent network protection solutions and afterwards easily analyse, tune and implement the chosen settings in the protection devices. The algorithm is flexible, automated and comprehensive featuring the following options:

  • User-definable coordination area
  • Automatic coordination of distance protection relays
  • Determination of relay protection zones
  • Reactive reach via zone-factors (independent, cumulative, ref. to line 1)
  • Resistive reach based on prospective fault/load resistance
  • Output options:
    • Tabular report
    • Time-distance diagram
    • Automatic update of protection devices
  • Time distance plots are automatically obtained after the algorithm

Cable Analysis

Cable Sizing
  • Automatic cable sizing based on IEC 60364-5-52, NF C15-100, NF C13-200, and BS 7671, etc.
  • Cable reinforcement optimisation
  • Verification of global and/or individual thermal and short-circuit constraints
  • Verification of user-defined voltage drops per terminal and/or feeders
  • Balanced (positive sequence) or unbalanced calculation with support of all phase technologies (1-, 2- and 3-phase systems, w/o neutral conductor)
  • System phase technology and cable type consistency checks in the feeder
  • Various verification reports and automatic modification of cable types in the existing network via network Variations
Cable Ampacity Calculation
  • Cable Ampacity calculation based on IEC 60287 or Neher-McGrath method
  • Evaluation of maximum allowable current for cables based on cable material, laying arrangement and environmental data
  • Rich reports and automatic modification of cable derating factors in the existing network via network Variations

Power Quality and Harmonic Analysis

The harmonic analysis functionality is ideal for applications in
transmission, distribution and industrial networks for filter design,
ripple control signal simulation or for the determination of network
resonance frequencies.

For analysing the impact of harmonics in power systems, DIgSILENT PowerFactory provides two harmonic analysis functions.

Harmonic Load Flow

The DIgSILENT PowerFactory harmonic load flow features the calculation
of harmonic voltage and current distributions based on defined harmonic
sources and grid characteristics. It allows the modelling of any
user-defined harmonic voltage or current source, both in magnitude and
phase including inter-harmonics. The harmonic sources can be located at
any busbar in the power system and may be implemented within any network

Harmonic current sources can be associated with any load, SVC (TCR
injection), rectifier or inverter. Harmonic voltage sources can be
modelled using the AC voltage source model or the PWM AC/DC converter
model. The built-in rectifier models inject the spectrum of ideal
6-pulse rectifiers if no other injection has been defined.

DIgSILENT PowerFactory supports any type of characteristic harmonic,
un-characteristic harmonic (even harmonics etc.) and non-integer
(inter-) harmonics. Unbalanced harmonic sources (e.g. single-phase
rectifiers) are also fully-supported. The analysis of inter-harmonics or
unbalanced harmonic sources is based on a complete abc-phase network

Because of the phase correct representation of harmonic sources and
network elements, the superposition of harmonic currents injected by
6-pulse rectifiers (via Y-Y and Y-D transformers leading to a reduction
in 5th, 7th, 17th, 19th etc. harmonic currents) is modelled correctly.

DIgSILENT PowerFactory calculates all symmetrical and asymmetrical
harmonic indices for currents and voltages, as defined by relevant IEEE
standards, including harmonic current indices and harmonic losses, such

  • THD
    and HD ((Total) Harmonic Distortion)
  • TAD (Total Arithmetic Distortion)
  • IT product
  • Harmonic losses
  • Active and reactive power at any frequency
  • Total active and reactive power, displacement and power factor
  • RMS values
  • Unbalance factors
  • Integer and non-integer harmonic order values
  • Flicker Assessment:
    • Pst, Plt (short- and long-term flicker disturbance factors; continuous an switching operation)
    • Relative voltage change value

Results can be represented:

  • In the single line diagram (total harmonic indices)
  • As histograms (frequency domain)
  • As waveform (transformation into the time domain)
  • As profile (e.g. THD versus busbars)

The frequency dependent representation of network elements such as
lines, cables, two- and three-winding transformers, machines, loads,
filter banks etc. for considering skin effects is fully-supported.

Frequency Sweep

The frequency sweep performs a continuous analysis in the frequency
domain. The most common application is the calculation of self- and
mutual network impedances for identifying the resonance points of the
network and for supporting filter design.

  • All impedances are calculated simultaneously in the same run.
    Since DIgSILENT PowerFactory uses a variable step-size algorithm, the
    calculation time of frequency sweeps is very low while the resolution
    around resonance points remains very high (typically 0.1 Hz)
  • Frequency sweeps can either be performed with the
    positive-sequence network model (very fast) or the complete three-phase
    abc-network model
  • Calculation of self- and mutual network impedances
  • Calculation of voltage amplification factors
  • Impedance plots may be created in either Bode, Nyquist or magnitude/phase forms

In addition to common applications relating to harmonic distortion,
PowerFactory’s Frequency Sweep function can also be used for
subsynchronous resonance studies. The calculation of damping and
undamping torques is supported by special scripts.

Network Modelling

The skin effect is considered by associating frequency
characteristics with line or transformer resistances and inductances.
These characteristics can be specified by either setting the parameters
of a polynomial expression or by entering the characteristic point by
point using tables. DIgSILENT PowerFactory uses cubic splines or hermite
polynoms for appropriate interpolation.

  • Lines are modelled either by approximate PI sections or by the highly-accurate distributed parameter
    line model that should always be used for long lines or high frequency
    applications. The skin effect can be included in both line models.
  • Filters can be specified by either ‘layout’ parameters or
    ‘design’ parameters. ‘Layout’ parameters are typically the rated
    reactive power, the resonance frequency and the quality factor.
    ‘Design’ parameters are the actual R, L, and C values.

In addition to the explicit specification of frequency dependent
resistance or inductance via parameter characteristics, overhead lines
can be modelled by defining the tower geometry and cables can be
modelled by specifying the cable layout. In such cases, frequency
dependent effects, such as the skin effect or frequency dependent earth
return, are automatically calculated and considered by the model.

Ripple Control Signals

DIgSILENT PowerFactory provides full support for analyzing and
dimensioning ripple control systems. Series and parallel coupling of
ripple control systems can be modelled including all necessary filter

  • The level of the ripple control signal in the entire network is
    calculated and reported in the single line diagram, the output window or
    the browser.
Filter Rating

DIgSILENT PowerFactory features a special, easy-to-use function for
calculating the rating of all components of a filter. All relevant
voltages across all components are calculated and made available in the
‘Filter Sizing’ report.

Power Quality Assessment according to D-A-CH-CZ Guideline

The Connection Request Assessment tool ia a very useful feature for power quality calculations according to D-A-CH-CZ guideline “Technical Rules for the Assessment of Network Disturbances” as used in Germany, Austria, Switzerland and Czech Republic. A new Connection Request Assessment command is available as well as the Connection Request element. This element represents a new load installation which is to be connected to the grid.

Full assessment of the D-A-CH-CZ guideline is performed based on the following criteria:

  • Voltage changes and flicker
  • Voltage unbalance
  • Harmonics
  • Commutation notches
  • Interharmonic voltages

Following the calculation, a detailed report and summary are made available for further analysis.

  • Phase 1: Sectionalising by remote controlled switch devices
  • Phase 2: Sub-sectionalising of strategic areas
  • Phase 3: Full system restoration

Sectionalizing supports serial or parallel switch actions (based on station access times).

  • Overload alleviation by optimised generator re-dispatch, load
    transfer and load shedding, under consideration of load priorities and
    the amount of load that is available for shedding.
  • Under-voltage load-shedding


For classical bulk power system analysis, it is assumed that post-fault
overloads may occur. A full AC load flow, incorporating basic generator
re-dispatch and automatic tap changing, is used to analyse post-fault
system conditions. Additional load transfer and/or load shedding will
then be simulated.

In cases where it can be assumed that system restoration will not lead
to any overloading, the overload alleviation can be omitted and a fast
network connectivity analysis is sufficient.

System Indices and Results

PowerFactory’s Network Reliability Assessment calculates all common
reliability indices. Among others, the following indices are available:

System indices (also available for user-defined feeders, zones, and areas):
  • SAIFI, System Average Interruption Frequency Index
  • CAIFI, Customer Average Interruption Frequency Index
  • SAIDI, System Average Interruption Duration Index
  • CAIDI, Customer Average Interruption Duration Index
  • ASIFI, Average System Interruption Frequency Index
  • ASIDI, Average System Interruption Duration Index
  • ASAI, Average Service Availability Index
  • ASUI, Average Service Unavailability Index
  • ENS, Energy Not Supplied
  • AENS, Average Energy Not Supplied
  • ACCI, Average Customer Curtailment Index
  • EIC, Expected Interruption Cost
  • IEAR, Interrupted Energy Assessment Rate
  • SES, System Energy Shed
  • LOLE, Loss of Load Expectancy
  • LOEE, Loss of Energy Expectation
  • LOLF, Loss of Load Frequency
  • LOLD, Loss of Load Duration
  • MAIFI, Momentary Average Interruption Frequency Index
Load Indices:
  • AID, Average Interruption Duration
  • ACIF, Average Customer Interruption Frequency
  • ACIT, Average Customer Interruption Time
  • LPIT, Load Point Interruption Time
  • LPIF, Load Point Interruption Frequency
  • LPENS, Load Point Energy Not Supplied
  • LPEIC, Load Point Expected Interruption Costs
  • LPCNS, Load Point Customers Not Supplied
  • LPPNS, Load Point Power Not Supplied
  • LPPS, Load Point Power Shed
  • LPES, Load Point Energy Shed
  • LPIC, Load Point Interruption Costs
  • TCIF, Total Customer Interruption Frequency
  • TCIT, Total Customer Interruption Time
Busbar Indices:
  • AID, Average Interruption Duration
  • LPIF, Yearly Interruption Frequency
  • LPIT, Yearly Interruption Time
Special Features

The Network Reliability Assessment is fully-integrated into PowerFactory, thus profiting from the extremely flexible data management and data management and data handling for setting up individual studies.

High Flexibility

Each contingency case is created and analysed based on events (i.e. switch events, load shedding events, generator re-dispatch events). By default, the events are created automatically by the reliability calculation algorithm. This allows the user to analyse, adjust and fine-tune the individual cases in a very flexible manner. The reliability calculation will then consider user-defined events for the FEA instead of creating them automatically.

Tracing of Individual Cases

The user can examine the results of a single fault by running the fault case of interest in the trace mode, a step-by-step analysis that sweeps over the individual actions of the FEA. The switching actions and load shedding/generator dispatch events created by the reliability calculation will then be applied to the network and the results can be viewed and analysed after each time step.

Powerful Output Tools for Result Representation

Results can be viewed in a variety of ways:

  • Formatted reports
  • Tabular result views (integrated into the PowerFactory Data Manager)
  • Graphical result representations
  • Various clouring modes
Contribution to Reliability Indices

Post-processing tools allow the calculation of individual components’ contributions to system indices. In this way the user can study the impact of certain network components (such as lines/cables, transformers, etc.) on the overall system indices. Likewise, loads can be grouped into load classes (industrial, agricultural, domestic, etc.) and their contribution to, for example, energy indices can be evaluated.

Development of indices over years

Taking into account the evolution of the network model and the failure data over time, PowerFactory supports the calculation and visualisation of the reliability indices over years.

Optimal Power Restoration

PowerFactory offers Power Restoration tools for distribution networks incorporating Tie Open Point optimisation methods to achieve an utmost level of resupply. For example, PowerFactory is automatically evaluating – as part of the Power Restoration strategy  – the benefits of any move of tie open points in any neighboring feeder.

Additional Features:

  • Unbalanced calculations
  • Handle of feeder constraints
  • Calculation of reliability indices
  • Use of load distribution states
  • Use of Time Tariffs and Energy Tariffs
Optimal Power Restoration

Optimal Power Restoration studies can be conducted for single case to obtain a “Recovery Scheme Report” – even in the case where no failure data is available for the network components. This function includes the feature to trace the stages of the restoration and view the impacts oh the restoration on the single line graphic.

Features are:

  • Animated tracing of individual cases
  • Optimal Remote Control Switch (RCS) placement
  • Optimal Manual Restoration