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 software.

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. TARA is licensed and used by every RTO/ISO in the country. TARA is a critical part of several production tool chains for Planning and Operations in the US.

Advantages of TARA

  • High performance analysis
  • Unique analysis components not found anywhere else
  • Extensive analysis types available with base TARA
  • Built-in batch mode automation for running, combining, and comparing results of multiple analysis scenarios
  • Supports all common powerflow file formats for input
  • Supports common supplementary formats contingency data, monitor elements, and subsystem data.
  • Support for both bus branch models and EMS nodal models
  • Includes support for nodal contingency files for use in contingency analysis and outage analysis on nodal cases
  • Supports several EMS case formats including a flexible, extensible INCH format
  • Multiple methods for automation include a mature scripting interface and a Python API
  • Flexible case modification markup format allowing case changes to be stored and shared without sharing the entire case
  • Python API available for base case modification and investigation
  • Ability to scale TARA deployments to cloud infrastructure and server level hardware using the same software
  • Primary TARA developers are engineers with extensive real-world production experience in Planning, Markets, and Operations
  • Simple installation structure requiring only a single executable and the TARAViewer for most use cases
  • Used in every RTO in the country in production

TARA Add-Ons Available for Purchase

  • Security-Constrained Dispatch finds a preventive dispatch that relieves post-contingency constraints (runs in DC or AC mode)
  • Generation Deliverability for PJM, MISO, and CAISO
  • Automated Model Builder for building future cases from seed cases
  • Outage Reliability Analysis for assessing outages
  • Cloud, Server, and Enfuzion Licensing for High Performance Computing

Additional PowerGEM Software Included with Base TARA

  • TARA Studio
  • pyPowerGEM
  • TARAViewer

Performance Analysis Modes

  • Batch processing for running multiple scenarios for each type of analysis in parallel using separate inputs
  • Multi-core analysis options available for most analysis types allowing TARA to completely use provided hardware
  • Cloud licensing available to site license to allow expanding into cloud infrastructure like AWS or Azure
  • Same software can be configured to run on personal computers or scale to server level hardware
  • Extensive automation options used in production tool chains all over the country

Core Analysis

Base TARA Analysis Features

  • Verifies powerflow data on input
  • High Performance N-1 AC and DC contingency analysis
  • DC contingency analysis with AC verification designed for fast analysis
  • High performance N-1-1 AC and DC contingency analysis with advanced screening options to eliminate running unnecessary contingencies
  • N-1-1 with smart cutoffs and comparative analysis to aid in viewing results and identifying critical issues.
  • Traditional FCITC analysis
  • Optimal MW Transfer analysis
  • 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
  • Extensive reporting in .csv files that are easy to read, sort, and parse
  • PV/QV analysis
  • Cascading contingency analysis
  • Ability to create cases with contingencies automatically applied
  • LF case editing using INCH (Incremental Changing)
  • INCH files can be used as input during batch processing to make changes to apply case changes for a specific scenario

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
  • PowerGEM has a .csv based EMS format used at 2 RTOs

Contingency Analysis

AC/DC Contingency Analysis

  • AC and DC Contingency analysis are core to TARA
  • Contingency analysis provides smart cutoffs for reporting to allow users to focus on critical overloads
  • Contingency analysis is designed with performance as a fundamental constraint
  • TARA has a proprietary DC contingency analysis method that is best in class
  • DC Contingency Analysis can be run with AC verification on flows over the DC limit
  • Contingency Analysis can be easily combined with SCD Add-On for finding a preventive dispatch
  • Contingency Analysis supports post contingency options
  • Q Relaxation can be used to provide a solution for difficult cases

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

Security-Constrained Dispatch

Security Constrained Dispatch

Automated Model Builder

Automated Model Builder

Outage Reliability Analysis

Outage Reliability Analysis

Generation Deliverabilty

Generation Deliverability