Transcript 4.2014 PGE_Base Case Loads_Transmission Model

Transmission Planning Base Case Loads
& Transmission System Model
Jameson Thornton
Anupama Pandey
Marco Rios
03/31/2014
Base Case Load Overview
1
• Objectives
2
• Method
3
• Process
2
Objectives (requirements)
• CAISO
– 1in5 system load suitable for high voltage system (230-500 kV)
assessment
– 1in10 area load suitable for local area network (60-230 kV)
assessment
• WECC
– Seasonal peak/partial peak/off peak loads as specified
3
Base Case Load Method
CEC system
forecast
Temperature,
coincidence,
Seasonal factors
Determine
“appropriate”
PG&E division
load
Conforming load
Non conforming
load
Muni load
Distribution
planning forecast
EMS data
Loss and other
adjustments
Other load, e.g.,
station service
Base Case Load
4
Seven Areas (20 Divisions)
Humboldt
North Coast
North Coast &
North Bay
Greater Bay Area
SF, Peninsula, De Anza,
SJ, East Bay, Diablo &
Mission
North Valley
Central Valley
Sacramento, Sierra, Stockton &
Stanislaus
San Joaquin Valley
Yosemite, Fresno & Kern
Central. Coast
& Los Padres
5
Process
• From system level forecast derive the area and the division level
forecast
− PG&E system is divided in to 7 areas
− Areas are further divided into 20 divisions
− Each division may have several distribution planning areas
• Derive Load Vs. Temperature relationship for each division
− Develop the starting point for the load for each division
• Meld Distribution and Muni forecast into Division forecast
• Allocate Division Loads to Transmission Buses
6
Load Growth
• Load growth is based upon:
– PG&E distribution load forecast
– CEC load forecast
• Two step process:
– Step 1: PG&E load growth (from CEC forecast) for the year is determined
– Step 2: Total PG&E load growth allocated to the division, based on the
relative magnitude of the load growths projected for the divisions by the
distribution planners
• Adjusted for temperature requirement
7
PG&E’s Transmission System
•
PG&E’s transmission system
encompasses a large and diverse
geographical area that includes vast
networked systems (vs. radial)
–
–
–
•
Provides service to over 15 million
people
70,000 square miles
Over 18,000 circuit miles of
transmission lines
PG&E’s transmission system is
divided into 7 local transmission
areas
–
–
–
–
Natural geographical boundaries
Electric system interaction
Weather pattern
The seven transmission planning
areas are further divided into 20 subareas (Divisions)
8
PG&E Transmission System Model
• PG&E is registered with NERC as a Transmission Owner
• CAISO is the Planning Authority for the PG&E system & PG&E follows the
CAISO Transmission planning process, procedures and standards
– CAISO span of control of PG&E system is from 500KV to 60 KV
• PG&E must demonstrate that its transmission system complies with all
applicable NERC/WECC/CAISO reliability planning standards.
– Maintenance of transmission system models
– NERC/WECC requires its members to provide detailed and accurate
transmission system representation
– Conduct transmission system assessment (other studies not related to NERC
Compliance are also performed)
• PG&E defines transmission voltage as 60 kV and above and as such the
associated systems are modeled in power flow base cases for
transmission planning studies (Distribution voltage class includes 21 kV
and below - not modeled)
9
PG&E Transmission System Model
• PG&E’s transmission system model includes detailed representation of all:
–
–
–
–
–
Transmission lines (sometimes in several segments)
Power transformers
Generators
Shunt devices (SVC, MSC, SVD, etc.)
Loads (conforming, non-conforming, self-generation and generation-plant
loads)
Note: Some substations connected only at the distribution level are not explicitly
modeled in the transmission system power flow model. Their load is aggregated
at the source substation with transmission level service.
• WECC is moving towards a detailed load model for use in dynamic
stability simulations
– PG&E’s current load modeling assumption provides a good foundation for
developing detailed load models for future use
10
PG&E Transmission System Model
•
Loads are
aggregated at the
high side of the
distribution
transformer
(transmission level)
•
This approach results
in a transmission
system model with
approximately 1300
buses with load
(including other
utilities such as
SMUD)
11
Questions
12