Scadainindianpowersystem Pka
Scadainindianpowersystem Pka
Scadainindianpowersystem Pka
SCADA
p r o j e c t
Indian power grid is a geographically dispersed network of generators having capacity more
than 147,000 MW, and transmission lines of 265,000 or more circuit kilometers. The generating
capacity is a mix of thermal generation, hydro generation and nuclear generation and also some
non-conventional generation like wind power etc.
- P K Agarwal
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Power System
SCADA system is
hierarchical in
nature having
two distinct
hierarchies one at national
level other at
regional level. At
national level,
SCADA/EMS
system of all five
RLDCs report to
NLDC.
Scada System
Hierarchical Structure
SCADA system is hierarchical in nature
having two distinct hierarchies - one at
national level other at regional level. At
national level, SCADA/EMS system of all five
RLDCs report to NLDC. Data from each RLDC
is transmitted to NLDC in real time on
dedicated communication lines. The national
level hierarchical arrangement is shown in
Fig. 2.
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Power System
Fig. 4: Typical Configuration of a RLDC and SLDC (Showing only main servers)
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Power System
Load Forecasting.
MIS Reporting.
Study mode functions
Power flow analysis.
Optimal power flow.
Study security enhancement
Study contingency analysis.
Study state estimation.
Resource
Scheduling
Optimization.
and
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Power System
At Sub-LDC/CPCC, functionalities of
Data server and ICCP servers have been
implemented on the same server
machine. Two such machines have
been provided. One server acts as main
while other acts as standby ready to
takeover the operation in the event of
failure of main server. The Typical
configuration of Sub-LDC and CPCC is
shown in fig. 5.
Like RLDC and SLDC LAN and WAN
equipment are also provided with back
up system. LANs are in
dual
configuration as LAN A and LAN B and
operates similar to LANs at RLDC and
SLDCs.
Similar to RLDC/SLDCs, here also,
communication with RTUs takes palace
through Communications Front End
(CFE). One CFE is on LAN A and other
on LAN B. Critical RTUs have two
separate communication channels one
for each CFE. Other RTUs, have single
communication channel but are
connected to both the CFEs through
splitters. Thus ensuring uninterrupted
availability of data in case of failure of
any of the equipment or communication
link.
Backup of Communication System
Sufficient redundancy has also been
provided for inter control center
communication so as to have 24x7 hrs
availability. All communication links,
devices like router for WAN required for
inter control center communication
have duplicate configuration. During
normal operation, flow of data takes
place on both the links in shared mode.
However, in the event of failure of any
of the link other link will take full data
flow.
Implementation of communication
system uses four communication
channels for each data link between
Sub-LDC and SLDC, between RLDC and
SLDC and between CPCC and RLDC.
These four communication channels
have been connected two separate
routers with two channels on each
router of LAN A and LAN B. Thus, each
router has main and stand by
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Power System
communication channel. In case of
failure of main channel, router switches
the communication of standby channel.
Further to this, main and standby
channels have been chosen from
different routes of MW/FO circuits
ensuring the availability of at least one
channel in case of any eventuality.
To enhance further availability the
main and stand by channel of a router
have been bundled through PPP
Multilink bundled protocol stack thus
forming a single virtual channel by
combining capacity of both the
channels. In this configuration, two
separate physical channels act in a
single virtual channel adding the
bandwidth capacity of both the
channels. As the requirement of
bandwidth is less than or equal to the
capacity of a single channel flow of
data remains uninterrupted in case of
outage of a one of the channel from the
bundled channel.
Conclusion
As described above though the
backup
concept
have
been
implemented at each and every point
of possible failure even the system may
not free form the situations were a
failure of some devices may lead to
interruption of operation. However,
possibilities of such situation are
remote.
To
provide
absolute
redundancy is nearly impossible. One
has to optimize between the project
cost and cost of outages. For example,
in this system CFEs are connected to
either LAN A or LAN B. One CFE may
communicate to one SCADA/EMS
server only i.e. CFE1 works with SCADA/
EMS server 1 and CFE2 is tied up with
SCADA/EMS Server 2. In this scenario
outage of crossed device, i.e. outage on
CFE1 and SCADA/EMS2 or outage of
CFE2 and SCADA/EMS server 1 may
result in the outage of data from all the
RTUs of that control center.
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