Development of of power plants functionality

IMPLEMENTING AN ELECTRICAL NETWORK
MONITORING AND CONTROL SYSTEM
Optimization of data network
by: Eng./ Hossam Ahmed Zein
MAY 20, 2014
CAIRO UNIVERITY
Faculty of engineering

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Transforming to Digital processing and
what challenges that exist
The main scopeis to combine multiple protections and metering Functions
into one device with basic I/O, sequenceof events which are developed to
have power quality monitoring, programmablelogic and high-speed Ethernet
Communications and a self-check feature.
The IED is the transformation of digital relays to multifunction intelligent
electronic device (IED) which capableto increase reliability due to reduced
wiring as mostof the logic can now be implemented within the IED and the
other development waveshould beto increasereliability due to reduced
wiring as mostof the logic can now be implemented within the IED.
The development of digital processing make it’s possible for development of
ELECTRICAL NETWORKMONITORING AND CONTROL SYSTEM (ENMCS) from
minimal hardwireddatagathering tolarge-scale monitoring of information
available over the communicationlinks, witha significant reductioninthe
cost of systemimplementation.
Controls via communication links resulted in long responsetimes,
unacceptable for motor or breaker control/feedback. Serial link setups with
large number of devices and/or large amounts of data being polled were
mainly responsible. Many different solutions wereused, including limiting

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device counts on serial links, reducing data collection volume, and reverting to
hardwiring.
Here is a comparison of multiple communications technology that supportthe
control network and which mustbe strictly considered in designing the overall
network.
Control and Monitoring Philosophy

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Initially this philosophy should be discussed between operations, maintenance
and engineering organizations which will help too in scopeidentification and
mitigate implementation difficulties related to scopegrowth and functional
split and this philosophy can be accomplishedby:
 The identification of the functional requirements and their
implementation across available controland monitoring system.
 All processes mustbeall functionally splitted to determine assign the
data sharing between control/monitoring and engineering access
locations.

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Functionality split
For example to clarify the functional split is (the motor control) considered as
a process controlsystem so it’s controlled totally fromthe DCS its interlocking
within the DCS logic.
Data share
For example in the motor there is a need to gain sharedata fromthe motor
protection relay with both DCS and monitor/controlsystem (ENMCS) that’s
because:
 The DCS requires data for online monitoring of the motor status and
metering (A, kW)
 The ENMCS requires a differentdata set; such as event records, motor
starting records, and power quality.
Note:The ENMCS mustalso have remote engineering access into the relay to
manage the relay settings and firmwaredownloads, thatis also
beneficial during pre-commissioning and commissioning.
And here is someways to handle the shared data between motor control
center (MCC) and controland monitoring systems:
 Approach #1

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o Motor control& monitoring implemented in the DCS with select
signals passed on to ENMCS.
o Makes it difficult to provideengineering access to the relays.
 Approach #2
o Motor control& monitoring implemented in the ENMCS with DCS
initiating control and receiving feedback via ENMCS.
o The systemmust poll for data it doesn’t need and then pass it on to
another system. (high traffic load)
o Makes it difficult to implement motor control and monitoring,
which is strictly a process controlfunction, via ENMCS, thus having
conflicting functional splits.
 Approach #3

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Using legacy serial protocols a full functional split can only be achieved using
two separateserial ports on the motor protection relays with separate serial
links, one to DCS and one to the ENMCS. However,
o This design doubles the number of serial loops and includes a large
number of physicalinterfaces between MCC, DCS, and ENMCS.
 Approach #4
ItCombine both Ethernet and seriallink protocols through gateways this will
achieve advantages of both protocols but still the combining itself between
two different protocols has problems as:
o Reducing the link reliability and extra programming by using extra note
(gateway) between MCC and DCS.
o Multiple loops resultin multiple loop checks which increase a limited
traffic
o Can’t achieve high data rate due to the lack of bandwidth of the serial
link itself.

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 Approach #5
The main idea is to use direct Ethernet ports on themotor protection
relays and
 Replacing the gateway (intermediate node) based architecturewith the
client server architecture allows multiple clients (DCS and ENMCS) to
communicate independently with the server (motor protection relays)
 Extend the bandwidth of the data bus which allow much higher data
rate and significantly increase in systemcapacity (A large number of
motor protection relays can be connected over a single physical link
between MCC and ENMCS/DCS, without loss of performance). In fact,
all the MV MCCs and switchgear in a substation can be served by a
single Ethernet ring network
 Due to the high level of performance at the lowestcommunication
levels, all motor start/stop commands and feedback (except safety
shutdown) can be over the communication network.
o The control/feedback action can be completed within 0.5 s to 1.0
s, depending on the relay response time.
 Allows long distance communication without any converters
(By using fiber optic cables and fiber optic porton the Ethernet Switch,
particularly useful for MCC’s located remotely fromthe DCS I/O
cabinet).
 Allows multiple protocols to be operated over the Ethernet layer, thus
providing communications flexibility.
 Engineering access for relay setting management and firmware
downloads is easier to implement with direct Ethernet access into the
relays.

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Finally
A control and monitoring philosophy, developed at an early stage, can help in
defining the scopeand its implementations across available plant control
systems with inputs from operation and maintenance organizations.
Appropriatecommunication network architecture and protocols should be

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identified. Ethernet is recommended to be adopted as the physical and data
link layer protocol. Engineering work processes should bedefined along with
clear scope boundaries across contracts.
Source:
INTEGRATED OPERATIONAND MANAGEMENTSYSTEM

Development of of power plants functionality

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