TOPAZ® Network Topology Analysis

Situation awareness in intelligent grid control centers depends on accurate results of real-time network analysis. In particular, state estimation and topology processing use telemetry data and network models to provide operators with good information on which security analysis can be performed.

State estimators must adjust for bad or missing data from the telemetry devices (SCADA). In large networks, or in areas where SCADA is not sufficiently deployed, topology errors are often difficult to detect or resolve. For example, manual breaker operations may not be correctly represented in the network model and lack of telemetry will induce an error on that breaker status (open when it may have been closed in the field). Such misrepresentation of breaker status can result in significant misinterpretation of grid reliability.

The NERC Reliability Standards in the U.S. call for systematic use of accurate state estimation in control centers. Nexant offers the world's most accurate state estimation software, GEN-SE® to achieve this purpose.

In addition, Nexant developed TOPAZ®, the only commercially available topology error estimation software today. TOPAZ can augment your state estimator to bring more situation awareness to operators by providing recommendations on how to resolve network topology errors.

TOPAZ is the result of our collaboration with the Electric Power Research Institute to develop a sophisticated and robust algorithm capable of overcoming topology error vulnerability to bad switch/breaker status data that most conventional energy management system state estimators have.

Using an advanced combinatorial bad data analysis technique, TOPAZ can identify topology errors such as bad circuit breaker or switch statuses and improve a state estimator's performance without necessarily replacing it.

TOPAZ can used as part of the real-time network analysis, with an interface built between the state estimator application within the EMS. TOPAZ can also be effective as a study tool to clean network models and understand the root causes of bad state estimator results. The application of both TOPAZ and GEN-SE has proven very valuable to one large U.S. ISO, identifying and justifying the need for additional SCADA points and quantifying the benefits of procuring additional RTU to transmission owners.

Key features of TOPAZ include:

• Speed-functions as the fastest, most robust tool for identifying and correcting circuit breaker and switch status errors from real-time telemetered data
• Comprehensive modeling-allows non-traditional devices such as switches to be explicitly modeled in the state estimator with their telemetered measurements
• Top-down design-treats the interaction of bad status data and bad analog data as a single, combined problem to be solved
• Solution robustness-implements an efficient approach to correctly identify erroneous measurements in configurations where multiple sets of interacting bad data are present
• Combinatorial analysis-provides a fast, comprehensive combinatorial search technique to identify and report multiple combinations of bad data that yield the same solution
• Modular software architecture-allows rapid interfacing to existing EMS systems or easy integration into any software environment