Transcript Idaho Power Nomogram

A new Nomogram Development POMbased tool - Application results in the
Idaho Power System.
Orlando Ciniglio, IPC
Marianna Vaiman, V&R Energy
WECC TSS Meeting, Salt Lake City, UT
January 20 - 22, 2015
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OUTLINE
1.
2.
3.
4.
Some background information
What is a Nomogram?
Basic Approach
Case Studies –


Midpoint West Vs COI
Idaho – NW Vs Limiting element
5. Conclusions
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Background Information
• Large GI work prompted need to study interaction between
existing path.
• It was determined that new project could be accommodated on
Midpoint West path and not impact existing transfer commitments
as long as heavy COI flows N-S were not concurrent.
• A 90% value for COI (only 10% of the time were COI flows
greater than this value) was determined, for the time period of
interest, based on historical records
• It was determined that a Nomogram between these two Paths
would help assess the potential interaction.
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Generic Problem Outline
• Want to find a Nomogram relation (boundary of operation)
between two “Paths” subject to thermal, voltage, flowability and/or
stability constraints.
– “Paths” can be
•
•
•
•
paths
Single Line
Generator(s) output
Load(s) level
– And observing limits in all other paths inside areas of interest
• By controlling load and generation within pre-specified constraints
in the areas of interest.
• For points at or inside the Nomogram boundaries, system
performance is acceptable (marginal at the boundaries) for all
4 credible outages.
Generic Problem Outline
(Basic Case)
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Generic Problem Outline
(Basic Case – cont)
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The Concept of a Nomogram
• Given:
– The paths of interest (x & y axes),
and
• By utilizing:
– A specified set of generators/loads in pre-defined areas
• In general, all of the generators/loads in the areas;
• The generation and loads in the selected areas are allowed to vary within a
pre-defined range ( i.e., [Pmax,Pmin], [Lmax,Lmin], for each generator and
load in the areas);
• Determine:
– The boundary of operation for simultaneous flows on both paths.
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
7
Basic Approach
• Constraints for Source/Generators:
Pmin for the generators (normally set to zero in the power flow cases) need to be
adjusted so that the following condition is met:
if(MinGenMW = 0, if(MaxGenMW > 0, min ( 0.5*MaxGenMW,MWGen),MinGenMW),MinGenMW)
– where if(( condition=true) x,y), means logical statement is evaluated to x if
condition is true, and to y otherwise.
• Establishes [Pmax, Pmin] for generators to that may be adjusted in the
process.
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Basic Approach (cont)
• Constraints for Sink/Loads:
Load min, for each load in the areas of interest is defined as:
• if(MinLoadMW=0,LDMIN*MIN(MaxLoadMW,MW),MinLoadMW)
• Where LDMIN is a factor, normally set to 0.8
• MW = actual load level
Load max, for each load in the areas of interest is defined as:
• if(MaxLoadMW>0,LDMAX*MaxLoadMW,MaxLoadMW)
• Where LDMAX is a factor, normally set to 1.15
• Establishes [Lmin,Lmax] for loads that may be adjusted in the process
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How the Nomogram is
Constructed in POM?
• For a Path X flow that is not less than a given value:
– Determines the required generation/load adjustments within their
limits in the user-defined areas, to cause Path Y to be maximally
increased until a violation (voltage/thermal/other path
flows/stability) is found.
– This will define one point on the nomogram.
• Changes Path X flow by a given amount, and repeats this
process to determine the corresponding Path Y level that
can be reached before a violation is found.
• Computes actual path flow limitations by using available
generators/loads, within their user-defined limits
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
10
Nomograms vs. Boundary
of Operating Region (BOR)
• Two different computations:
– BOR is AC transfer analysis simulation for 2 (or 3) simultaneous
transfers
– Nomograms is an optimization computation
• BOR:
– Sources and sinks are defined
– Changes load/generation in sources and sinks until a violation of
monitored constraints occurs
– Computes flows on the interfaces (paths)
• Nomograms:
– Selects which combination of generators/loads to adjust and by how
much from the specified list
– Maximizes the interface (path) Y flow, while keeping interface (path)
X greater than a given value, before reaching a violation
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
11
Input Data to Build
a Nomogram
• The following information is necessary to build a
Nomogram:
–
–
–
–
A Power Flow Case.
Description of the two paths; flow on one of them is maximized.
Description of other limiting paths with their flows limits.
List of generators/loads that can be adjusted in order to maximize
flows on selected paths, as well as their allowed variation range.
• For example, for generators Pmin/Pmax specified in the base case can be used
– Monitored elements (for voltage and thermal constraint
monitoring) and limits.
– Contingency list.
– Solution options (enable/disable control of ULTCs, phase shifters,
SVDs, etc.)
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
12
Output Files
• Program outputs results of computations to four files
• File #1:
– The file contains information about the calculation step at which power flow
through Path 1 reaches its maximum for a given limit value of power flow
through Path 2.
1450 34 1280.77
1500 34 1280.77
– Each record contains three
1550 9 1277.86
space-delimited fields:
1600 27 1274.35
• Limit value of power flow through Path 2;
• Step number;
• Power flow through Path 1 calculated by script
BuildNomogramFinal.txt.
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
13
Output Files (cont.)
• File #2:
– The file contains detailed information about the calculation step at which power
flow through Path 1 reaches its maximum for a given limit value of power flow
through Path 2.
– The file consists of several types of records:
• The first record contains:
– Limit value of power flow through Path 2;
– Step number;
– Power flow through Path 1 calculated by script BuildNomogramFinal.txt.
• The second record contains information about particular loads/generators used at
calculation step listed in the first record, including bus number, generator/load ID,
and the value of real power at this calculation step.
• The last record contains a list of violations that limit increase in power flow through
Result for 1000 15 1319.76
Path 1.
1 60077 1
56.52
1 60100 1
137.5
2 60151 1
76.68
Violation:
Midpoint-Hemingway 500kV -1514.4 MW (not in -1500.0..1500.0)
Swing Bus 1046.3 MW (not in 0.0..710.0)
Copyright © 1997-2016 V&R Energy Systems Research,
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Output Files (cont.)
• File #3:
– The file contains computation results for all steps at which power flow through
Path 1 is computed for a given limit value of power flow through Path 2.
– File format is the same as the file format shown above.
• Program also creates and saves new Power Plow Cases in .epc format
for each point on the nomogram:
– User defines which point(s)/step(s) to save.
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
15
Graphical Output:
POM Nomograms
• Nomograms are built automatically:
– In this example, computations are done with a 50 MW step
Voltage/Thermal Constraint Not Monitored
Voltage Constraint Monitored /
Thermal Constraint Not Monitored
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
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Conclusions
• The process is automated
• Computes and plots the entire boundary, not just one single
point
• Identifies the mix of generation and loads that should be
used to maximize the path flow
– Optimization algorithm allows to maximize path flow
Copyright © 1997-2016 V&R Energy Systems Research,
Inc. All rights reserved.
17
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Case Study #1
• Want to find a Nomogram relation between Midpoint West and COI (N-S)
flows, subject to:
– Midpoint – Hemingway < 1500MW
– Hemingway – Summer Lake < 1500MW
– COI flow >= 1920MW ( North to South).
– And observing limits in all other Paths inside areas of interest
• By controlling load and generation within pre-specified constraints in the areas
of interest:
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–
–
–
–
–
–
–
–
60 Idaho
62 Montana
64 Sierra
65 Pace
40 Northwest
30 PG & E
26 LADWP
73 WAPA R.M.
Midpoint West Vs COI
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COI flows > ~1930MW
(10% of the time under light load hours)
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Midpoint West / COI Nomogram
(no voltage/no thermal constraints)
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Midpoint West / COI Nomogram
(voltage/no thermal constraints)
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Midpoint West / COI Nomogram
(voltage and thermal constraints)
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Questions
?
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