Transient Security Assessment Tool (TSAT)

Indroduction

Transient Security Assessment Tool (TSAT) is a software tool jointly developed by Powertech Labs Inc. (Powertech), Canada, and Nanjing Automation Research Institution (NARI), China. TSAT is designed to meet growing challenges facing the power industry in a deregulated and open-access environment. The perfect performance of TSAT helps giving accurate and reliable transient security assessment of the power system under rapidly changing operating conditions.

Technology

TSAT is based primarily on two techniques:

  • The step-by-step time-domain simulations, developed at Powertech. This ensures that very complicated and large-scale power system models can be analyzed with the best possible accuracy.
  • A quantitative stability assessment method using the Extended Equal Area Criterion (EEAC), developed at NARI. This method is capable of, with fast computation speed, providing quantitative stability indices for specific stability scenarios, which are essential for the transient security assessment of a power system.

The integration of these two techniques is a tool that provides advanced computational capabilities for the security assessment. The use of the EEAC technique is essential in some of the core functions in TSAT, including

  • Fast contingency screening. This helps eliminate the non-critical contingencies from the detailed analysis, thereby speeding up the on-line security assessment of large-scale power systems. 
  • Computation of transient stability index (including CCT). This index is critical in assessing the transient security status of a system for a given system condition and contingency scenario, in both off-line and on-line analysis. 
  • Early termination of time-domain simulations. By applying the EEAC technique, the simulations can often be terminated with the correct stability index computed, before the specified simulation length. Considerable computation time savings can be made with this feature.
  • Power transfer limit determination. One of the problems in TSA is to determine the maximum power transfer capability across an interface, subject to stability constraint. TSAT can automatically compute such transfer limits, with the help of the stability index.

The techniques and algorithms used in TSAT have been tested very extensively for models of many power systems worldwide. Very accurate and reliable results were obtained in these tests.

Application

TSAT is now the standard analysis tool at Powertech for all of our worldwide engineering consulting business that requires stability analysis. The recent applications of TSAT includes,

  • A research project sponsored by PRECARN (a major Canadian industry funding agency) for applications of intelligence techniques in power system security assessment (a joint research work by Powertech, IREQ, and Alberta Research Council). The objective of this project is to develop fast and reliable security assessment of power systems using artificial intelligence methods. In this application, TSAT plays the key role of performing base security analysis to build case databases from which various intelligence methods are trained.
  • Underfrequency load shedding scheme review and evaluation for the Southwest Power Pool (US) and Newfoundland Hydro (Canada).
  • System integration studies for new IPPs for Entergy Services Inc. (US), Southern Company Services (US), TVA (US), PJM Interconnection (US).
  • System expansion study for TransAlta (Canada).
  • Testing and validation of generator and associated control models for BC Hydro (Canada) and various IPPs in Canada and US.
  • Stability studies for Austin Energy (US).
  • System studies and the remedial action scheme (RAS) design (Taiwan).
  • System studies and the remedial action scheme (RAS) design (Saudi Arabia).
  • Tuning of control systems (including exciter and PSS) for PJM Interconnection, ERCOT ISO, Dynergy.
  • Time-domain verification studies in a small signal stability study for ERCOT ISO (US).
  • Time-domain verification studies in voltage stability studies for ERCOT ISO (US) and TransPower (New Zealand).

TSAT has started to gain momentum in the power industry as the next generation stability analysis tool. Among the current users are,

  • ERCOT ISO (US). TSAT is used in its new EMS system to perform on-line dynamic security assessment of the entire Texas system. This system has completed the factory acceptance testing. In addition, TSAT is used in off-line stability studies at ERCOT ISO.
  • Ameren UE (US). TSAT is used in off-line stability studies.
  • Entergy Services Inc. (US). TSAT is used in off-line stability studies.
  • American Transmission Company (US). TSAT is used in off-line stability studies.
  • FinGrid (Finland). TSAT is used in off-line stability studies.
  • State Power South Company (China). TSAT is used in off-line stability studies.
  • Universities in Canada, US, China (including Hong Kong), Korea. TSAT is used in teaching and research.
  • Guangxi Power Company (China). TSAT is used in its EMS system to perform on-line dynamic security assessment of the entire South Power System of China. TSAT is also used in off-line stability studies at Guangxi Power Company.