Energy Management System

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Energy Management System
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System Level Functions

• Energy / Power Managment System
• To keep power system running at optimal
  conditions under constraints for the actual
  operation
• The Power Management system comprises the
  following basic functions
• Generator control (for diesel, turbine and shaft
  driven generators)
• Switchboard control
• Circuit Breaker control

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Low Level Control and Protection

• Engine Protection and Governing
• Protect diesel engine from damage, monitoring and
  shut-down
• Speed control and load sharing
• Automatic Voltage Regulators (AVR)
• Voltage control and reactive load sharing
• Protection Relays
• Protect el. System from overloads etc.

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Power Plant
Vessel Loads
Propulsion Auxilliaries
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Synkronisere generatorer

• Spenningsløs tavle
• Generator har riktig frekvens (Riktig turtall)
• Generator gir nominell spenning (Magnetisering)
• Neste generatorer
• Generator gir samme spenning som tavle
• Riktig frekvens
• Er i fase med tavle
• Avvik fører til
• Spenning Skjevfordeling av reaktiv effekt
  (motordrift)
• Frekvens Mekanisk belastning på generator

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Parallelldift av generatorer

• Frekvensstatikk lik
• Hastighetsfall ved lastforandring mest mulig lik
• Den minst fallende vil ellers ta all last.
• Regulering Turtallsregulering
• Spenningsstatikk
• Spenningssfall ved lastforandring
• Den minst fallende vil ta all reaktiv effekt og
  prøve å drive de med lavere spenning.
• Regulering Magnetisering

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SVC- Hovedfunksjoner

• The SVC Power Management comprises the following
  basic functions
• Diesel Generator Control
• Turbine Driven Generator Control
• Shaft Generator Control
• Switchboard Control
• Load and Consumer Control

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Tilleggsfunsjoner

• Automatic opening of bus-ties in a total blackout
  situation
• Automatic routing of power from the high voltage
  to the low voltage switchboard after a blackout
  situation has been removed
• Automatic opening of the transformer high voltage
  circuit breakers when a blackout occurs to
  suppress transformer surge current
• Automatic restarting of thruster motors from a
  different switchboard after a partial blackout

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Diesel Generator Control

• Diesel Generator Control covers the following
• Manual Control Functions
• Automatic Control Functions
• Safety Functions
• Exhaust Gas Monitoring
• Alarm Inhibiting

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Manual Control Functions

• The following control functions are available
  when the Diesel Generator Control function is in
  the manual mode
• Diesel Start/Stop
• Generator Connect/Disconnect
• Manual Load Sharing
• Fuel Selection
• Pre-lubrication

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Diesel Start/Stop

• Manual start and stop of the diesel engine of
  each Diesel Driven Generator (DDG) is available
  at all SVC operator stations.
• A manual start will initiate a DDG start sequence
  if no external start block signals are active.
• Normally three engine start attempts can be
  performed, and if a start is not successful after
  the third attempt a start failure alarm will be
  given.
• A manual stop will initiate a stop sequence
  provided that the DDG is not connected to a
  switchboard.
• When the DDG has come to a complete stop,
  auxiliary systems are stopped, and preheater and
  prelubrication are started.

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Generator Connect/Disconnect

• Connect command activates the synchronising unit
  which
• checks if frequency and voltage deviations
  between the generator and the net are within
  system limits and, when the phases are equal,
  closes the appropriate generator circuitbreaker.
• Disconnect
• If the automatic load sharing function is
  activated the engine will be loaded off to a
  specified limit (typical 10) before the circuit
  breaker opens.
• The system will however prevent disconnection if
  theresult will be overload on the remaining
  diesel engines.

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• Manual frequency/load sharing control is
  accomplished by
• giving a DDG engine speed "increase" or
  "decrease" command.
• Fuel Selection
• Some diesel engines can be run on both light and
  heavy fuel oil. This can be manually controlled.
• Pre-lubrication
• With the automatic Pre-lubrication function
  implemented, the pre-lubrication pump of a DDG
  will be started and run for a setperiod of time
  when the DDG is started or stopped.

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Power Management
Schematic overview of power production and
distribution
Generator symbol text instrument panel
Main Switch Board load - and consumer control
Bus tie
Emergency generator, not operational
Heavy consumers, not operational
.
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Automatic Control Functions

• The following Control Functions are available
  when the Diesel Generator Control function is in
  the Automatic mode
• Automatic Frequency Control
• Fixed Load
• Symmetric Load Sharing
• Asymmetric Load Sharing
• Load Dependent Start/Stop
• Load Limitation
• Blackout Restart

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Automatic Frequency Control

• Speed control of a DDG
• is primarily performed by the DDG's governor
• with secondary adjustments being performed by the
  Automatic Frequency Control function.
• Based on measurements of the net frequency, the
  Automatic Frequency Control function will
  regulate the speed setpoint of the running DDGs.

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Fixed Load

• When fixed load is selected for a DDG, the load
  will be kept steady for this engine.
• The load variations will then be shared by the
  other engines.
• This selection can be overridden by the Load
  Sharing system to prevent overload or reverse
  power on the other connected engines.
• The operator can change the fixed setpoint by
  means of the "increase" and "decrease" commands.

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Load sharing

• Symmetric Load Sharing
• Engines, which are selected for symmetric load
  sharing, will automatically share the same
  percentage load.
• Asymmetric Load Sharing
• Can be made separately for each DDG and
  independent of each of the other DDGs.
• The purpose of using the asymmetric load sharing
  function is to burn off accumulated carbon inside
  Diesel Engines by running each of them as a main
  DDG with an optimum constant load for a
  pre-defined period of time.

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Assymetric load sharing

• The other running DDGs are used as "topping up"
  DDGs.
• If the load on the "topping up" DDGs drops to a
  pre-defined minimum level, the load of the "main"
  DDG will be reduced.
• The function can be selected when the total power
  demand (load) is less than approximately 50 of
  the maximum available power.

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Load Dependent Start/Stop 1

• A load dependent start can be initiated by one of
  the following configurable conditions
• The consumed power exceeds the available power by
  a pre-set percentage.
• The difference between the available power and
  the consumed power is less than a pre-set value
  (in kW).
• The electric current level, delivered from one
  generator, exceeds a predefined limit.

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Load Dependent Start/Stop 2

• A load dependent start is delayed by a time
  filter in order not to be activated by short load
  peaks.
• It has its triggering point defined by a set of
  start limits (1 and 2) whose values depend on the
  number of connected DDGs.
• Each limit in the set of limits can be given a
  different delay time to make it possible to have
  a load dependent start with a short time delay
  for large loads.

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Load Dependent Start/Stop 3
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Load dependent stop 1

• A load dependent stop can be initiated by one of
  the following configurable conditions
• The consumed power, represented as a percentage
  of the available power from the remaining
  connected DDGs, is less than a pre-defined value.
• The difference between the available power from
  the remaining connected DDGs and the consumed
  power exceeds a pre-set value (in kW).
• A load dependent stop is delayed by a time filter
  in order to prevent a stop based on short load
  variations.

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Load dependent stop 2

• The operator can select which DDG should be the
  standby for a load dependent start/stop.
• As an option, a value for the potential extra
  load, based on the running status of the heavy
  consumers (thrusters, large pumps etc.), can be
  calculated and added to the measured generator
  load within the Load Dependent Start/Stop
  function.

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Load dependent stop 3
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Load control limitation

• A DDG will take up the load in a manner that is
  defined by a pre-programmed load control
  limitation curve.
• The load limitation program will be bypassed for
  conditions thatrequire a full load for reasons of
  operational safety.

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Blackout Restart

• The Diesel Generator Control function detects a
  blackout by monitoring
• DDG circuit breakers,
• bus-ties
• shore connections
• When a blackout is detected, the DDGs with
  asymmetric load sharing will be set to symmetric
  load sharing.
• After a blackout situation has occurred, power is
  restored by reconnection of either the first
  standby DDG or all standby DDGs in numerical
  sequence.

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Shut Down

• If any of the following signals from a DDG enters
  an alarm state, an immediate stop of the DDG will
  be initiated together with a request for the
  start of the next standby DDG
• Low lubrication oil pressure
• High cooling water temperature
• Over speed
• Customer specified
• After a Shut Down, the DDG concerned is
  automaticallyblocked by the Diesel Generator
  Control function.

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Alarm Start

• Alarm Start can cause one of the following to
  occur
• DDG change-over with stopping of the faulty DDG
• DDG change-over with a cooling stop of the faulty
  DDG
• Standby DDG start without stopping the faulty DDG
• The DDG which initiated the alarm is unloaded,
  disconnected and stopped with or without a
  cooling down period.

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Alarm Inhibiting

• When a DDG is detected as "stopped" alarms
  related to that DDG and its associated
  auxiliaries will be inhibited except for those
  given by pumps
• Engine running (digital)
• Engine speed (analogue)
• Generator voltage
• Generator circuit breaker

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Shaft Generator Control

• Shaft Generator Control can be implemented with
  and without main engine speed control.
• Main engine speed control is normally not used
  when the size of the SG is small compared with
  that of the main engine.
• For both alternatives, the main engine must be
  set to "fixed speed" (not "combinatory") before
  the SG can be connected to the net.
• The synchronising unit controls the main engine
  pilot motor.

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Switchboard Control

• The Switchboard Control functions cover the
  following
• Bus-tie Control
• Circuit Breaker Control
• Transformer Monitoring

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Bus-tie Control

• Bus-tie Connect
• The Automatic Frequency Control function will
  adjust the frequency of the two switchboards to
  be slightly different from each other (in order
  to have phase rotation).
• When the voltage, frequency and phase deviations
  between the two switchboards are acceptable it
  will Connect
• Bus-tie Disconnect
• The load on the generators will be distributed to
  minimise theelectric current flow in the bus-tie.

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Circuit Breaker Control

• Control and monitoring
• Circuit breakers to emergency switchboards
• Synchronisation and connection of shore and
  harbour generators
• Automatic reconnection of high and low voltage
  bus bars and transformer circuit breakers can be
  implemented (after a blackout).
• An interlock system for the circuit breakers can
  be implemented to avoid dangerous combinations.

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Load and Consumer Control

• Non-essential Consumers
• To protect the power generating system from
  overload and to prevent blackouts
• Generates a signal to trip the consumers
• This signal will be given after the load
  percentage has been at a customer-defined level
  for a configurable period of time.

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Heavy Consumers

• Connected by request/block signals to prevent a
  blackout at start up.
• All heavy consumers that are not running are
  automatically blocked.
• Start If sufficient power is available, the
  state of the "start block" signal changes to
  "non-block".
• If sufficient power is not available, the standby
  generator will automatically be started up.
• To prevent blackout in case of a generator trip
  it can calculate which thruster is to be
  tripped.
• This information will be continuously update to
  the fast tripping logic in the switchboard(s).