Chapter 2.5: Model Development

Chapter 2.5: Model Development

Transmission system models are the foundation of the MTEP analytical processes. The viability of the study results hinges on the accuracy of the models used. Planning model development at MISO is a collaborative process with significant stakeholder interaction and neighbor coordination. Stakeholders provide modeling data, help develop assumptions for modeling future transmission system scenarios and review the models. MTEP models are also coordinated with MISO’s neighboring entities and their system representation is updated based on their feedback.

MTEP15 underwent some expansion in the model building process. MISO developed a powerflow and dynamics model suite based on the new TPL-001-4 standard, which included new sensitivity scenarios to be built. Secondly, there were two sets of models built, driven by the Expansion Planning’s study process change. One model set contained approved future projects from MTEP14 Appendix A, and the other model set contained approved MTEP14 Appendix A projects and projects targeted for approval in MTEP15.

Changes in the MTEP15 model-building process include additional powerflow and dynamics models based on a new standard

For MTEP studies, models for steady-state powerflow, dynamics stability reliability and economics are built to represent a planning horizon spanning the next 10 years. The primary sources of information used to develop the models are:

  • MISO’s Model on Demand (MOD) powerflow base case with future project information
  • MISO members, including Transmission Owners, Generation Owners and Load-Serving Entities
  • Eastern Reliability Assessment Group (ERAG) Multi-regional Modeling Working Group (MMWG) series models used for external area representation
  • ABB PROMOD PowerBase database
  • Neighboring planning entities

MTEP models are interdependent (Figure 2.5-1).

Figure 2.5-1: MTEP15 model relationships

Figure 2.5-1: MTEP15 model relationships

Reliability Study Models

Powerflow Models

MISO developed regional powerflow models for MTEP15 as required by the new TPL-001-4 standard (Table 2.5-1). Developed model base cases and sensitivity cases are listed with the TPL-001-4 requirement.

Model Year Base Case Models Sensitivity Models
Year 2 2017 Summer Peak (Wind at 14.7%)
TPL requirement R2.1.1
2017 Light Load (minimum load level) (Wind at 0%)
TPL requirement R2.1.4
Year 5 2020 Summer Peak (Wind at 14.7%)
TPL requirement R2.1.1
2020 Light Load (minimum load level) (Wind at 90%)
TPL requirement R2.1.4
2020 Summer Shoulder (70-80% peak)
(Wind at 40%)
TPL requirement R2.1.2
2020 Summer Shoulder (70-80% peak)
(Wind at 90%)
TPL requirement R2.1.4
2020/21 Winter Peak (Wind at 30%) MISO MTEP model Not required
Year 10 2025 Summer Peak (Wind at 14.7%)
TPL requirement R2.2.1
Not required
Table 2.5-1: MTEP15 Powerflow Models

Assumptions regarding inclusion of future transmission, generation and load facilities are:
Load – Load is modeled based on seasonal load projections provided by member companies to the MISO MOD system.
Generation – Existing generators are included. Planned generators with signed Generation Interconnection Agreements are included according to their expected in-service dates.
Transmission Topology —Two sets of powerflow models were developed:

  1. MTEP14 Appendix A, which includes only future approved transmission facilities first approved in MTEP14 and future projects approved in prior MTEP studies.
  2. MTEP14 Appendix A plus MTEP15 Target Appendix A: This includes future transmission projects approved in Appendix A through prior MTEP studies and new transmission projects submitted for approval in the MTEP15 planning cycle to verify their need and sufficiency in ensuring system reliability

LBA Generation Dispatch Methodology

The generation dispatch in steady-state powerflow models is done at the Local Balancing Area (LBA) level. Network Resource type generation is dispatched in an economic order to meet the load, loss and interchange level for each LBA. The area interchange for each LBA is determined by the transaction table agreed upon by transaction participants, and the generation is dispatched to account for the cumulative MISO net area interchange level. Wind generation is typically an energy resource; however, wind generation is dispatched in models to address renewable energy standards. Wind generation is dispatched at capacity credit level in summer peak models and average and high levels in off-peak models. The percentage values for wind generation (Table 2.5-1), are based on the nameplate capacity.

  • 7 percent is wind capacity credit based on MISO’s Loss of Load Expectation study
  • 40 percent represents the average wind output level
  • 90 percent represents the high wind output level
  • 30 percent represents the wind output level in the winter model

 

The input of LBA dispatch is the generation and load profile data submitted by members in the MOD system. Output of generators is determined considering several factors such as seasonal output variations, equipment limitations, policy regulations, approved retirements and local operational guidelines for reliable grid operation. Behind-the-meter generation, hydro machines and non-MISO generation information is retained from generation and load profiles submitted in MOD. Energy resources are not dispatched except for wind resources as described above.

During the model development process, powerflow models are reviewed for reasonableness of data and performance. This review is achieved through extensive data checks, stakeholder reviews and feedback. MISO planning staff produces a model data check and case summary document, which is made available to the stakeholders along with the models.

Within the system conditions for each MISO control area for 2017 summer and 2020 summer models, there may be differences in the load values for each area from the Module E load values due to inclusion of station service loads and non-member loads embedded in MISO members’ model control areas (Table 2.5-2).

Area 2017 Summer Peak
(all numbers in MW)
2020 Summer Peak
(all numbers in MW)
GEN Load Losses Area
Interchange
GEN Load Losses Area
Interchange
HE 1,282 510 26 746 1,126 526 25 576
DEI 7,591 7,416 314 (145) 7,940 7,554 314 65
SIGE 1,692 1,803 30 (141) 1,776 1,797 29 (50)
IPL 3,013 2,921 80 8 3,055 2,961 80 11
NIPS 3,308 3,643 55 (396) 3,450 3,760 61 (376)
METC 11,296 9,991 341 964 11,543 10,099 335 1,109
ITCT 10,927 11,418 242 (733) 10,810 11,385 245 (820)
WEC 6,650 6,436 99 103 6,717 6,559 101 45
MIUP 514 617 24 (128) 520 630 25 (136)
BREC 1,387 1,765 19 (396) 1,617 1,781 15 (179)
EES-EAI 9,004 7,738 197 1,068 9,217 7,951 175 1,088
LAGN 2,946 1,432 21 1,493 2,636 1,506 18 1,112
CWLD 226 390 1 (74) 248 417 1 (49)
SMEPA 1,124 789 23 312 1,194 817 23 355
EES 21,702 22,937 456 (1,701) 22,422 24,136 475 (2,198)
AMMO 9,287 8,767 185 334 9,362 8,691 199 472
AMIL 10,535 9,637 230 668 10,777 9,362 232 1,183
CWLP 519 439 4 76 516 449 4 64
SIPC 476 335 16 125 486 354 15 117
CLEC 3,423 2,713 67 643 3,641 2,833 73 735
LAFA 230 481 7 (259) 253 515 7 (269)
LEPA 87 229 0.1 (143) 92 235 0.1 (143)
XEL 9,253 10,353 263 (1,377) 9,433 10,585 244 (1,409)
MP 1,729 1,856 55 (184) 1,689 1,889 75 (277)
SMMPA 136 612 2 (478) 144 643 1 (500)
GRE 2,459 2,673 88 (304) 2,482 2,690 89 (300)
OTP 2,094 1,366 85 641 2,141 1,428 84 626
ALTW 3,984 4,059 83 (158) 4,161 4,262 89 (190)
MPW 225 162 1 62 223 164 2 57
MEC 5,827 6,004 92 (269) 5,828 6,196 93 (461)
MDU 421 685 14 (278) 420 738 14 (333)
DPC 917 1,061 41 (185) 909 1,091 41 (222)
ALTE 3,590 2,704 81 800 3,648 2,790 81 772
WPS 2,117 2,710 54 (652) 2,114 2,761 55 (707)
MGE 368 766 10 (410) 338 786 11 (460)
UPPC 60 234 8 (182) 57 236 8 (187)
140,394 137,560 3,308 (549) 142,985 140,454 3,337 (880)
Table 2.5-2: System conditions for 2017 and 2020 models, for each MISO control area

Dynamic Stability Models

Dynamic stability models are used for transient stability studies performed as part of NERC TPL assessment and generation interconnection studies (Table 2.5-3). New stability models for study are required for TPL-001-4 standard.

Model Year Base Case Dynamic Models Sensitivity Dynamic Models
Year 5 2020 Summer Peak (Wind at 14.7%)
TPL requirement R2.4.1
2020 Light Load (minimum load) (Wind at 90%)
TPL requirement R2.4.3
2020 Summer Shoulder (70-80% peak) (Wind at 40%)
TPL requirement R2.4.2
2020 Summer Shoulder (70-80% peak) (Wind at 90%)
TPL requirement R2.4.3
Table 2.5-3: MTEP15 dynamic stability models

The MTEP14 dynamics data was the starting point for MTEP15 dynamics model development. This data was updated with stakeholder feedback to develop the MTEP15 dynamics models. Additionally, the ERAG MMWG 2014 series dynamic stability models were reviewed and any improved modeling data was incorporated in the MTEP15 dynamics models.

Dynamic stability models included new dynamic load modeling practices driven by the new TPL standard

There is significant enhancement in load modeling in MTEP15 dynamic models driven by Requirement 2.4.1 of the TPL-001-4 standard. The load models must be represented by complex or composite load models to adequately capture the impact of induction motor loads. Assumptions for generator dispatch for stability models are identical to steady-state powerflow models.

The dynamics package is verified by running a 20-second, no-disturbance simulation and some other sample disturbances at select generator locations in the MISO footprint. Simulation results show expected performance of generators and active elements within the MISO system. Charts showing simulation results are posted for stakeholder review.

During the MTEP15 dynamics models review, stakeholders were asked to provide inputs on:

  • Updates to existing dynamics data
  • Additional dynamic models for new equipment
  • Output quantities to be measured

Economic Study Models

Economic study models are developed for use in the MTEP economic planning process. These models are forward-looking, hourly models based on assumptions discussed and agreed upon through the stakeholder process. For MTEP15, the Planning Advisory Committee (PAC) approved the following future scenarios:[1]

Central and North Regions

  • Business as Usual (BAU)
  • High Growth (HG)
  • Limited Growth (LG)
  • Generation Shift (GS)
  • Public Policy (PP)

 

South Region

  • Business as Usual (BAU)
  • Generation Shift (GS)
  • Public Policy (PP)
  • South Industrial Renaissance (SIR)

 

The base data used in all future scenarios is maintained through the PROMOD PowerBase database. This database uses data provided annually by ABB as a starting point. MISO then goes through an extensive model development process that updates the source data provided by ABB with more accurate data specific to MISO.

Updates include data obtained from the following sources:

  • MISO Commercial Model for generator maximum capacities and hub data
  • Generator Interconnection Queues (MISO and neighbors) for future generators
  • Module E data for energy and demand forecasts, behind-the-meter generation, interruptible loads and demand response data
  • Powerflow model (developed through the MTEP process) for topology
  • Publically announced generation retirements
  • Specific stakeholder comments/updates
  • Generation capacity expansion (developed by MISO staff — see Chapter 5.2: MTEP Future Development)

 

As part of the economic model development process, the PowerBase database is verified to ensure data accuracy through numerous checks. Model verification is broadly comprised of generator economic data validation, demand and energy data checks and PowerBase-powerflow network topology mapping.

The PowerBase database, including system topology, was posted for stakeholder review. During the review period stakeholders were asked to provide:

  • Updates to generator data
    • Maximum and minimum capacity
    • Retirement dates
    • Emission rates
  • Updates to powerflow model mapping to PowerBase
    • Generator bus mapping
    • Demand mapping
  • Updates to contingencies and flowgates/interfaces monitored

 

In addition to the stakeholder review process, MISO collaborates with neighboring entities to develop a coordinated model that more accurately reflects the neighbors’ systems. Highlights of this collaboration include extensive updates from Pennsylvania-based PJM Interconnection and Arkansas-based Southwest Power Pool (SPP).