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At Cernavoda NPP Unit 1 the control functions related to BOP areas and Support ... modules (Slaves) by means of the Expander Bus, a high-speed parallel bus, and ... – PowerPoint PPT presentation

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UNIT 1 BOP Control Architecture
  • At Cernavoda NPP Unit 1 the control functions
    related to BOP areas and Support Systems were
    provided by some different systems
  • - Nuovo Pignone for Analogue Control
  • - Leeds Northrup for Winding Temperature
    Supervisory system (temperature signals related
    to motors, compressors and transformers)
  • - Marconi for Digital Control
  • - ORTEC panels in Main Control Room (MCR), for
    control, indication and supervision functions
  • - other dedicated local panels for the
    integrated Support Systems (Pump- House, HVAC and
    D2O tower systems), such as York cubicle for
    Chillers, AECL / Gec-Alstom for Sequencers or
    Romanian products.

  • The technology of these systems was mainly
    based on hardware interconnections point to
    point between field instruments, logic cabinets
    in Equipment Room (E/R), with electronic cards
    and cabled static elements, and a conventional
    operator interface in Main Control Room (MCR)
    with hand switches / push-buttons,
    electro-mechanical indicators (EMI) and different
    signalization lights (alarms, status, ...).
    Functional Group commands for Digital Control,
    with the single component commands located inside
    the logic cabinets in E/R, or from local panels
    close to the equipment in field were also
  • The digital signals to/from the field or MCR,
    conditioned and manipulated in local
    instrumentation panels, were transmitted to/from
    Marconi cabinets passing through a Central
    Distribution Frame (CDF) located in E/R. The
    dispatching function of the signals between the
    various CI components (included Plant Computers
    (DCC X/Y), for trending, data logging,
    supervision activities, and some control
    functions) was provided by CDF.

UNIT 2 BOP Control Architecture
  • In Unit 2 all the different and formerly
    foreseen Control Systems are replaced with a
    single product, a Distributed Control System
    based on processor technology, able to integrate
    all typical control functions (modulating and
    digital controls, supervision and alarm, etc.),
    and to use an advanced Operator Interface too.
  • The DCS Automation Nodes are distributed over
    the Plant, located as close as possible to the
    process areas where the controlled components and
    sensors are. Commands/signals to/from MCR are
    handled by cabinets located in the adjacent E/R.
    All the signals are multiplexed, the cabling and
    terminal connections numbers are reduced, the
    cable-trays layout are optimized, and the
    communication buses run all over the BOP area.
  • The Unit 2 BOP Control Architecture includes
    the traditional MCR operator interface (hand
    switches / pushbuttons, electro-mechanical
    indicators, lamps, window tiles) already supplied
    for MCR.
  • Only the A/M Stations for manual modulating
    control located onto the MCR boards has been
    replaced by new corresponding DCS units (with a
    little carpentry arrangement only), so keeping
    the same functional interface by the operator
    point of view. The other A/M Stations and digital
    manual units located in E/R will be replaced by
    Virtual Control Panels onto an Operator Station.

  • Software Operator Stations are also used for
    the Winding Temperature Supervisory system, for
    the overall BOP supervision, including the
    control of some Support Systems (Pump-House,
    HVAC, D2O Up-grading, partially Chillers,
    Compressors and Stand-by Diesel Generator
    Sequencer functions).
  • These Operator Stations will be distributed
    over the Plant. An Engineering Work Station (EWS)
    for Configuration and Tuning functions is
    provided too.
  • The DCS main features base on open
    architecture, modularity, expandability, high
    reliability, respect of the safety constraints,
    ease of use and of keeping pace with further
    technology evolution.
  • Dedicated requirements are easily implemented
    in terms of Redundancy, Channelization,
    Functional Partitioning, Fault-tolerance, Safe
    failure modes, and are detailed in the
    followings. But evident advantages are also
    obtained by considering the amount of hardware
    reduction, the flexibility of software
    optimization and the high standardization degree,
    which permits drastically lowering the
    implementation working efforts. Test,
    installation, commissioning, operating and
    maintenance activities can be made simpler than
    in case of a traditional hard-wired approach.

Criteria to allocate I/O signals into the DCS
  • The DCS Architecture is influenced by the
    fulfillment of some general Design Criteria
  • - geographical distribution of DCS equipment
    (function of I/O signals location too),
  • - redundancy of all critical components
    (multifunction controller, communication
    interface and bus, power source)
  • - channelisation (Even/Odd lines),
  • - functional partitioning of Plant systems
    (partitions 1/2/3 or NP1/NP2/NP3),
  • - categorisation of Plant systems
    (Safety/Non-Safety Related systems).
  • These criteria have to be achieved also
    considering to optimize the Automation System
    performances (as response time, global
    throughput, data traffic on communication bus,
    ...), and to conform reliability/availability to
    Plant demands.
  • It is requested to have a separation by the
    point of view of either the hardware
    configuration or the software implementation.

  • There is a hierarchy among the previous
  • - identify the different Plant areas where DCS
    cabinets should be placed
  • - assume the proper redundancy of DCS
    master/slave modules (influencing the cabinets
  • - analyze the Channelization (Even/Odd lines)
  • - separate the signals considering the
    Functional Partitioning criteria
  • - separate the signals by the Categorization
    criteria (if it is possible)
  • Hence, the input signals shall be grouped,
    considering the location of instruments, local
    panels and controlled devices and the appropriate
    distribution of DCS cabinets. These groups
    include all signals pertaining to each Even or
    Odd line, separated successively among the
    Partitions 1, 2, 3, NP1, NP2 and NP3 (and Safety
    or Non-Safety Related systems too). All the
    involved Plant signals will be distributed
    between the resulting different sub-groups, and
    correctly assigned to different DCS cabinets.
  • The following flowchart, (F1), identifies the
    sequential steps to define the I/O signals
    allocation into DCS cabinets, in accordance with
    the hierarchic structure formerly noted (and also
    considering an appropriate internal layout of DCS

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Geographical Distribution of DCS cabinets
  • Considering the BOP signals handled (for
    acquisition/actuation functions), and their
    availability all over the Plant included also
    those related to Pump-House, HVAC and .D2O
    Up-grading. systems and taking into account the
    former assumptions the geographical localization
    of DCS cabinets involves the following areas
  • - Turbine building (T/B el. 100)
  • - Electrical Bay (E/B) Even (el. 111.5) and
    Odd (el. 121.5) Rooms
  • - Equipment Room (E/R - Service building (S/B)
  • - Chillers building (C/B)
  • - Pump-House (P/H) Control Room (el. 103)
  • - HVAC Control Room (Heater Bay (H/B) el. 127)
  • - D2O tower Control Room (el. 105)
  • - Stand by Diesel Generators Building

  • DCS cabinets manage all the signals correlated
    to the equipment and devices in field and on the
    MCR local panels, are supplied either by Even or
    Odd power supply lines in each Plant area and are
    interconnected to separated Even or Odd DCS
    networks (both redundant). These signals shall be
    mainly assigned to the Even or Odd channel, and
    consequently to the Even and Odd DCS cabinets, in
    accordance with the following rules and criteria
  • - the signals shall be assigned to the same
    channel to which the process equipment or device
    is associated
  • - the signals shall be assigned to the separated
    Even and Odd channel when redundant process
    equipment or devices are used,
  • - where the above two rules do not apply, the
    signals shall be mainly assigned in order to
    achieve a balance between channels.
  • Even/Odd Channelization requirement has to be
    fulfilled also for the signals associated to the
    digital (by conventional HS/PB units) and
    modulating controls (by A/M Stations supplied
    with DCS equipment) that are located inside the
    MCR boards, and displayed onto a Software
    Operator Station (Virtual Control Panel) in E/R
    or anyway.

Functional Partitioning
  • In consequence of the Functional Partitioning
    requirement stated before, the signals belonging
  • - Instrument Air (75100-.) systems
  • - Main Feed-Water (43230) and Condensate
    (43210-43220) systems
  • - Service Water (71300-71340-71350) systems
    shall be allocated in separated DCS cabinets.
  • All the just defined systems are Safety Related
  • This requirement, although not strictly
    mandatory, has been adopted to permit also a
    physical separation that shall assure an
    independent functionality for the three
  • The first set of DCS cabinets is defined
    Partition 1 (e.g., Process Control Unit 01, 02,
    05, 06, 09, 10,.) the second set of cabinets is
    defined Partition 2 (e.g., Process Control Unit
    03, 04, 07, 08, 11, 12,.) the third set of
    cabinets is defined Partition 3 (e.g., Process
    Control Unit 13, 14).
  • With Process Control Unit is intended the DCS
    standard logic cabinet with the associated
    termination units cabinets.
  • Once the process systems defined in the
    previous step are assigned to DCS cabinets of
    Partitions 1, 2 and 3, the other signals to
    integrate into the DCS Architecture (pertaining
    either to Safety or Non-Safety Related systems)
    are successively associated to the DCS Process
    Control Units.

Functional Partitioning
  • For these signals, as stated before, a
    Partition NP (non partitioned), and a
    successive grouping in three sub-groups
    identified as NP1, NP2 and NP3, has been
    conventionally defined. They can be allocated
    together the signals associated to Partition 1, 2
    and 3 without any peculiar constraint (in the
    related cabinets PCU 01, 02, 03, 04, ., 13, 14).
    The association of these signals to one of the
    above listed Partitions is mainly based on
    functional considerations, process correlation
    and/or some specific conveniences (homogeneity
    and acceptable filling of DCS cabinets,
    considering also the requested .free space. to
    provide, etc.).
  • However, at the present time most of the signal
    of the systems collected in Partition sub-group
    NP1 have been allocated with the systems
    identified as Partition 1, those pertaining to
    Partition sub-group NP2 with the systems
    identified as Partition 2, and those pertaining
    to Partition sub-group NP3 with the systems
    identified as Partition 3.

  • The signals related to Safety and Non-Safety
    Related systems could be assigned to different
    I/O slaves, placed in different racks of the same
    logic cabinet.
  • The separation between safety and not-safety
    related systems, although not required by DCS
    Design requirements, is opportune for a clean
    panel filling, from a design point of view, and
    for a more functional Plant operability and
    maintenance activity, but it is not strictly

Additional Requirements
  • The standard signals associated to A/M Stations
    for modulating control (e.g. 1AI, 1AO, 1DI and
    1DO) must be collected together, associated to a
    specific DCS I/O Slave module and a related
    conditioning unit to put inside the proper DCS
  • All conventional A/M Stations are located on
    the MCR boards and the related signals are
    allocated and assigned to the same Partition of
    the controlled device, thus they too achieve the
    partitioning rules already defined.

  • This section describes the physical arrangement
    and technical architecture of the Distributed
    Control System (DCS) related to the Cernavoda
    Unit 2 NPP.

General Description
  • The implemented Automation Architecture
    consists of a number of Processing Control Unit
    (PCU) cabinets, of associated Termination Unit
    (TU) cabinets, of some communication loops, of
    communication bridges between them, of all the
    required cabling and connections. The cabling may
    be of various types (hardwiring, optical fibers),
    depending on the particular functions.
  • It reflects the general functional philosophy
    of Odd/Even separation and some other criteria
    (e.g.Partition) within each process system.
  • In each PCU cabinet there are a number of
    digital processing electronic equipment modules,
    plus power supplies, cooling fans, racks with
    connections. The number of functional modules
    varies from a cabinet to another. Each PCU
    cabinet contains processor modules, a
    communication port, plus a number of slave
    analog/digital input/output modules (for a total
    of at most 96 electronic cards). The TU cabinets
    only contain input and output termination unit
    module cards.
  • Each equipment of the DCS is housed in steel
    cabinets, except for the display monitors and
    peripheral equipment.

  • The DCS performs the following control
    functions in an integrated solution
  • - Closed Loop Control
  • - Open Loop Control
  • - Alarm Management
  • - Plant Supervision
  • - Signal acquisition, conditioning and
  • The DCS for CERNAVODA Unit 2 NPP is an
    Integrated Process Automation System based on the
    ABB Symphony Harmony Rack I/O System with TENORE
    Operator Interface Stations.
  • Specifically designed for process management,
    Symphony Harmony System architecture is based on
    the high speed, high throughput (10 Mb), and high
    security C-NET Data Highway.
  • C-NET is a scaleable and unidirectional Control
    Network, forming a ring to grant a higher
    security, which connects all the Process Control
    Units (PCUs) and the TENORE Operator Interface
    Stations (OIU).

  • Several C-NET rings are connected together by
    means of Bridge devices (INIIL/INIIR) in a STAR
  • The heart of Symphony Harmony is the Multi
    Function Processor (MFP) module, that is the
    equivalent of a stand-alone process computer
    without the added complexity. Each MFP processes
    the downloaded control program, which implements
    the control strategies, handling thousands of
    analog and/or digital Input/Outputs.
  • The MFP communicates with I/O modules (Slaves)
    by means of the Expander Bus, a high-speed
    parallel bus, and with the other MFP.s and the
    C-NET node of the PCU by means of the Control
    Way, 1 Mb Ethernet type network.
  • The Symphony Harmony multi-layered hierarchical
    communication architecture is represented in the
    following Figure 1.

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System Overview
  • The following Figure 2 shows the general layout
    of the DCS dedicated to Cernavoda Unit 2.

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