Transcript State Estimator Implementation at PacifiCorp: Challenges

State Estimator Implementation at
PacifiCorp: Challenges and Experience
By Real time Apps
Team
Grid Operations
PacifiCorp
Company Overview
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PacifiCorp is one of the leading utilities in the west part of United
states, serving about 1.7 million customers in six western states. The
company was acquired by MidAmerican Energy Holding Company in
2006. It has three primary subsidiaries:
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Pacific Power - a regulated electric utility with service territory throughout
Oregon, northern California, and southeastern Washington.
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Rocky Mountain Power – a regulated electric utility with service territory
throughout Utah, Wyoming, and southeastern Idaho.
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PacifiCorp Energy - operates 70+ generation facilities in the six states that
Pacific Power and Rocky Mountain Power operate in, plus two facilities in
Montana, three in Colorado, and one in Arizona.
PacifiCorp EMS System
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PacifiCorp’s EMS system supports operations of all three subsidiaries.
Two redundant pairs of servers reside in Pacific Power Control Center
and Rocky Mountain Control Center.
SCADA, AGC, SE and other Advanced Applications are all running on
a primary server and can be failed over to the back-up server in the
other control center.
Every three weeks, a database with SCADA and model changes and
software upgrades are integrated and tested on the development and
QAS servers.
Software and database updates are deployed onto production servers
after succesful testing and approval on QAS servers.
EMS system is protected with firewalls and isolated from the
corporate’s main network per NERC CIP standards.
PacifiCorp Network Model
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PacifiCorp Legacy EMS had eight different systems and databases.
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It did not have State Estimator and other Advanced Applications before
the 2006 upgrade.
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It was challenging to build the model from scratch.
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WECC spans portions of Canada, Mexico and fourteen Western U.S.
states.
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As PacifiCorp resides in this WECC region, we started with WECC
planning model.
PacifiCorp Network Model
PacifiCorp Network Model (External)
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Some WECC external areas are far away from our control areas and
are thereby less relevant to the PacifiCorp internal models.
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Using PTI Network equivalence software, most of the external model
which is 69 kV and below was eliminated (with an exception for
generator buses).
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The backbone and most of the bulk power system model (230 KV and
500 KV) of the Western Interconnection was maintained.
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Some of the 100 KV to 230 KV networks were also maintained
depending on geography and how relevant they were to the internal
systems, and all tie-lines with PacifiCorp.
PacifiCorp Network Model (Internal)
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The PacifiCorp model has two internal areas. One area is PACE
(Rocky Mountain Power) and another is PACW (Pacific Power). Three
major efforts to complete the SE model:
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The entire bus/branch model derived from PTI was replaced with the
detailed SCADA one-line node-breaker model. The nameplate details of
numerous equipment in the model were gathered to verify and update the
accuracy of the static model.
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Initial Load flow solutions were successfully obtained after less than one
week of load flow tuning with the vendor’s help.
Mapping detailed SCADA breaker statuses, telemetry meters of MW,
MVAR, KV and Tap positions received from RTU or via ICCP to equipment
in the model for the SE
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PacifiCorp Network Model
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The combined PacifiCorp internal and external model footprint:
Load Flow Buses 5600
Circuits
7500
Transformers
2300
Units
1200
Loads
3900
Shunts
(Caps/React)
840
Switches
27000
Model Update and Maintenance (Why is this
a Big deal?)
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PacifiCorp is going through tremendous infrastructure growth
especially in the Utah area of Rocky Mountain Power.
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Adding new transmission lines, new wind farm generators, new
load substations are included in this growth.
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Updating the network model to reflect all the new changes and
keeping the model and mapping in sync with the SCADA
database are big issues for PacifiCorp to maintain the SE
solution as valid and up-to-date.
Model Update and Maintenance with CIM
DE Tool (Conversion)
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The model was initially built and populated in the vendor’s source data
format.
CIM DE tool was introduced later to allow the users to have better
version control, model updates and CIM data import/export.
Among the first group of customers to implement “reverse
engineering”: converting the model and data from source data into the
CIM database.
Two sets of data and table conversion involved:
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CIM/XML compliant data: those related to the pure network model;
non-CIM compliant data: including CIM extention tables for SCADA and
AGC data.
Model Update and Maintenance with CIM
DE Tool (Internal)
PROD
NEXT PROD
SCADA
User 1
NETAPPS
User 2
User 3
User 4
Model Update and Maintenance with CIM
DE Tool (External)
CIM XML
Files
CIM XML
Files
CIM DB
PacifiCorp SE tuning experience
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Identified and mapped measurements exactly where they are
measured.
Modeled the tap changer on the correct side of the transformer.
The voltage ratio is a key for the reactive power flow in a fixed tap
transformer
Assigned correct weights to the real and pseudo measurements.
Series compensators in the model caused quite a bit of a challenge
during the tuning phase.
Added ZERO impedance lines to map the measurements to the bus
side of the series capacitors and shunt reactors.
PACW is closely inter-tied with other utilities like PGE and BPA. This is
another significant challenge we are facing with the model on the west
side of PacifiCorp (PACW)
Developed a in-house tool to capture SCADA measurements snapshot
from production to development system
PacifiCorp EMS Advanced Applications (Current)
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State Estimator
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Real Time Contingency Analysis
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On production Nov. 2008
Runs every 5 minutes
99.5% valid solutions.
On production Nov. 2008
Runs every 15 minutes (3 cycles of SE)
More than 1000 contingency cases
Dispatcher Load Flow
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On production Nov. 2008
Save cases are archived for up to six months.
Supports eight study users
PacifiCorp EMS Advanced Applications (Future)
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Day Ahead Studies
– Generating unit and interchange schedules
– Load forecast data
– Scheduled Outages
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Dispatcher Training Simulator
– DTS is a stand alone server.
– Mimics the production EMS system
– Provides a realistic method for training operators
Industrial Challenges
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It is very important to improve the quality of field measurements. Some
meters have not been checked out for a long time.
Lack of real time telemetry on observability of SE. Adding new meters
and meter replacements in the internal area require huge
commitments in money and resource.
How to get changes quickly reflected in the model is a very challenging
task. More processes and coordination need to be defined.
New changes in the external area of the model require information
sharing among utilities. Such tools or agreements are not yet readily
available.
Field changes have to be mirrored in the EMS real time database.
Especially for those non-telemeter pseudo breakers.
The robustness of SE is still a very important subject.
Real-Time Applications Team Members
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Madhukar Gaddam is Senior Applications Engineer in Real Time Applications
at PacifiCorp. He previously worked in ABB, AREVA and CMC India. He has
Masters in Electrical Engineering (Power systems) from Indian Institute of
Technology, Kanpur, India and is a Senior Member of IEEE.
Rick Nielson is Lead/Senior Engineer in real time Applications group at
PacifiCorp. He previously was with Utah Power and Light. He has a Bachelors
degree in Electrical Engineer from the University of Utah in Salt Lake City,
Utah.
Giridhar Valmikam is a Sr. Power System Consultant working for CompuSharp
Inc. He was previously with Exelon Corporation, Chicago. He has a Masters
degree in Power Systems from NIT, Warangal, India and is a Member of IEEE.
Peng Li is Principal Engineer and Real Time Applications team lead at
PacifiCorp. He previously was with Canadian Space Agency, ABB and Nortel
Networks, He has PhD degree in Electrical Engineering (Control Systems) from
University of Ottawa, Canada and is a Member of IEEE and Senior Member of
AEE.