Generation Deliverability

TARA - Transmission Adequacy & Reliability Assessment


TARA Generation Deliverability (GD) add-on applications are focused on custom processes performed by several US ISOs as the part of new resources interconnection procedures or transmission planning studies. TARA GD provides highly efficient complete automation of complicated GD procedures allowing to model very large ISOs footprint with many thousands of contingencies as well as providing interactive drill down analysis mode. Conceptually all TARA GD methods utilize similar two step approach

  1. Extensive TARA propriety flowgate screening to identify flowgates and dynamic generation pockets that may be limiting the output of the generation under study under different dispatch patterns.
  2. Create LF dispatch case for each identified potentially limiting flowgate to perform the final GD analysis

Three separate add-on applications are available to reproduce GD calculations as performed by PJM, MISO and CAISO. TARA GD add-ons have been developed over many years in cooperation and support from these ISOs. Assuming identical input options and input data obtained from ISOs, TARA users should obtain very similar or near identical results to the generation deliverability tests for transmission planning and generator interconnection studies in RTOs/ISOs.

Generation Deliverability

Gen Deliv Features

  • Helps you obtain nearly identical results to various ISO/RTO Generator Deliverability tests
  • Perform what-if scenario analysis to study multiple scenarios
  • Filtering of reports and other features for aiding with finding the impacts of your project
  • Detailed reports show each component of the deliverability test condition for a given flowgate
  • PJM GD has batch automation for increasing amount of studies that can be run
  • TARA Flowgate screening engine with years of design iteration and a focus on performance
  • Custom flowgate screening focused on the “study generator” concept to identify only those flowgates that are relevant to “my” study generators to avoid analysis on numerous unrelated constraints inherent to the case
  • Identify potential violations contributed by either injection or withdrawal (for example, battery projects), and by generators not only in “my” region but also generators in the neighboring regions
  • User friendly interface with many custom features.
  • GD reports and interactive drill-down analysis; Detailed reports show each component of the deliverability loading contributions for a selected flowgates
  • Uses DC linearized loading with AC validation to significantly increase performance

Official ISO/RTO Tool

PowerGEM GD tools are the officials tools used by PJM, MISO, and CAISO for generation deliverability studies. Users who want to match the ISO/RTO results can use the TARA generation deliverability tools instead of developing their own tooling internally.

PJM Generation Deliverability

PJM Generation Deliverability is an add-on for TARA. TARA PJM GD add-on has been implemented via a separate standalone Excel GD application automating up to five different flowgates screening runs utilizing different screening parameters depending on contingency type (single, tower, bus, breaker, and operation) and then up to five different GD stress tests for different contingency types. To improve the analysis performance TARA PJM GD extensively utilizes multi-core capability and batch mode processing. Details of PJM GD study procedures are described in PJM Manual 14B, Attachment C.3: Deliverability of Generation.


MISO RIST is an add-on for TARA. MISO RIST Includes two applications:

  1. MISO NRIS (Network Resource Interconnection Study) tool implementing GD process as used by MISO for network resource. Prior to performing NRIS tests users will need to perform TARA flowgate screening available within base TARA module. MISO NRIS study procedures are described in MISO BPM 015, Appendix C.
  2. MISO ERIS (Energy Resource Interconnection Study) tool focuses on resource deliverability of energy resources focused on thermal analysis. MISO ERIS voltage studies can be performed using TARA N-1 cross-comparison batch automation. MISO ERIS study automation in TARA is based on TARA’s capability to work with multiple load flow cases and to provide fast comparative DC/AC contingency analysis DFAX calculation, and flexible Mon/Con type loading calculation. This provides significant reduction of efforts as MISO ERIS analysis involves many tens of thousands N-1 and N-2 contingencies. MISO ERIS study procedures are described in MISO BPM 015, Chapter 5.

CAISO Generation Deliverability

CAISO GD is an add-on for TARA. CAISO GD also fully utilizes TARA’s high performance capabilities for flowgate screening, DFAX calculation, and fast AC solution. Execution of CAISO GD add-on requires two steps:

  1. Perform flowgate screening available within base TARA module using CAISO GD specific screening options.
  2. Run GD analysis can be performed via very detailed AC mode and faster linearized DC mode. If users enable Generation Capacity Reduction (GCR) option, TARA will run GCR routine if the final %loading is greater than 100%. CAISO GD assessment methodology is described in CAISO Deliverability Assessment Methodology.

ISO/RTO Input Data

PowerGEM is not responsible for maintaining the generation deliverability data and will not release any powerflow data. That data will need to be obtained from corresponding ISO/RTOs and will require following the ISO/RTOs processes for acquiring that data. Please contact the corresdonding ISO/RTO if that data is needed.