TARA - Transmission Adequacy & Reliability Assessment


TARA is a steady-state power flow software tool with modeling capabilities and analytical applications that extend beyond traditional power flow solution.

Using extraordinarily robust and speedy linear (DC) and non-linear (AC) power flow calculations, TARA integrates data checking, N-1/N-1-1 reliability analysis, transfer limit calculation, preventive and corrective dispatch, critical facility identification, reactive analysis, outage analysis, model building, and region specific tools for generation deliverability and reserve requirements analysis.

Advantages of TARA

  • High performance analysis
  • Unique analysis components not found anywhere else
  • Mature user friendly Excel user interface, reporting and many right mouse click context based functions
  • Built-in batch mode automation for running and comparing results of multiple analysis scenarios
  • Scriptable for automated processes that can run outside of Excel

TARA Add-Ons Available for Purchase

  • Security-Constrained Dispatch (SCD)
  • Automated Model Builder (AMB)
  • Outage Reliability Analysis (ORA)
  • Cloud Computing

Core Analysis

Verification of data and filterable reporting of input data errors

N-1 DC and AC traditional contingency analysis, DC with AC verification

N-1-1 with smart cutoffs and comparative analysis to aid in viewing results and enhanced performance

Traditional FCITC analysis

(Optional add-on) Security-Constrained Dispatch finds a preventive dispatch that relieves post-contingency constraints (runs in DC or AC mode)

Multi-Core functionality is available for many analysis types

Dfax calculation for generation and load on N-1 constraints or on flowgates/interfaces

Unique Flowgate screening can create flowgate files for other applications

Corrective switching search

SPS/RAS modeling as the part of N-1 and SCD (coming)

LF case visualization

Supported Models

Traditional Planning models and contingency files

  • Bus/Branch approach
  • Eastern, Western, and Texas cases
  • Read and save LF case directly with no additional conversion

EMS models

  • Full bus/breaker topology reading
  • Build cases from EMS model CSV files
  • Apply historical dispatch of generation/load/pars
  • Output cases in traditional powerflow case formats
  • Preserve all EMS information
  • Model reduction to improve performance
  • Experience with largest EMS models in the US

LF case editing using INCH (Incremental Changing) allowing to run multiple scenarios, especially in batch mode without direct change of LF cases

Security-Constrained Dispatch

Security-Constrained Economic Dispatch (SCED) minimizes total bid production cost while observing N-1 constraints

Security-Constrained Redispatch (SCRD) minimize total amount of MW redispatch while observing N-1 constraints

Both preventive and corrective modes are available

Phase Shifter optimization.

High performance – SCD can enforce 10,000+ contingencies in preventive mode for LF cases with 70,000+buses

Able to optionally enforce N-1 AC post-contingency flows

Can be used in conjunction with N-1-1 analysis

PV and QV

PV Tool

  • Finds transfer violations due to non-convergence, thermal, and voltage criteria
  • Fast screening to identify contingencies that cause transfer violations
  • Full search for selected contingencies to find transfer point that causes violations
  • Report all monitored buses and branches for all contingencies for all tested transfer points for powerful data review capabilities
  • Plot functions are available after review of data and determination of limiting buses

QV Tool

  • Test multiple buses and contingencies
  • Comprehensive data reporting for all test points for powerful data review capabilities

Automated Model Builder

Build AC-solved cases that represent future time periods

Incorporates load forecasts, generation outages, transmission outages, and area-to-area transactions

Can use NERC SDX for source of load forecasts, outages, etc for US Eastern Interconnection LF cases. Various data formats are supported.

Options available for redispatching include block dispatch, unconstrained economic dispatch, and security-constrained dispatch

Run as a script-based automated process or through Excel-based user interface

EMS-based AMB uses full EMS network data and historic dispatch as a basis to build future cases


Outage Reliability Analysis

Use Planning or EMS models

Perform a before/after analysis for each outage

Do standard N-1 DC/AC analysis or do Security-Constrained Dispatch

Various approaches for evaluating a queue of outages (cumulative, one-at-a-time, etc.)

Analyze multiple time periods together in a single session (e.g. next 30 days)

Run as script-based automated process or through an Excel user interface

Multi-Core mode

See http://www.ferc.gov/CalendarFiles/20140411125613-M3%20-%20Condren.pdf for more info


Helps you obtain similar results to various ISO Generator Deliverability tests

Filtering 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