Undergraduate Research and Teaching Opportunities from a Transient Network Analyzer

A Transient Network Analyzer (TNA) is a large, controlled hardware simulation environment for studying electrical faults. Background is presented on how the university acquired a TNA from a public utility and adapted it for use in teaching and research. System is described with specifications. Capstone design process combined with a solid funded followup serves as a means to leverage the creation of such large research tools. Details of ideas for design, implementation, projects, and data collection are presented. Introduction A Transient Network Analyzer (TNA) is a controlled hardware environment with which engineers can intentionally create and observe real electrical faults on a scale model power distribution system. A TNA has the main elements of a section of the commercial electrical grid, such as lines, sources, transformers, loads, instrumentation, and protection. There is a significant degree of flexibility for interconnection and instrumentation. Appropriate scaling of voltages, currents, impedances, and other quantities permit its behavior to safely mimic the transient performance of a section of the grid. Many utilities own such hardware. Larger TNAs have replaced smaller ones or, more frequently, advanced digital simulation systems have taken the place of TNAs. Occasionally, a TNA becomes available for university donation. The question then becomes how to install such equipment on limited university resources. In this paper, such a TNA provided an opportunity for undergraduate research and teaching. Through a series of projects, the TNA was installed and outfitted for use in both research and teaching. By combining the enthusiasm and ideas of the capstone design process with a solidly funded followup, a working tool became available. This paper begins with a synopsis of TNA’s history, background, and initial installation. Through a sequence of capstone design projects, the feasibility of tools and enhancements is investigated and a host of good ideas are discovered. Those ideas were incorporated into the TNA by a funded research team. Details of the TNA’s performance and the design of research tools are presented in this paper. Applications for teaching, particularly at the introductory level, are also explained. In other words, scarce research money is leveraged effectively by a combination of the capstone design and a thorough followup process to yield a useful tool for both research and a broad range of teaching. Background Idaho Power Company designed and built a TNA to enable its engineers to analyze portions of its grid. After a period of service with the company, the TNA was donated to the University of Idaho in 1999. The Schweizer Engineering Company donated state-of-the-art protection equipment during the following year. Unlike its public utility applications, the TNA now Proceedings of the 2002 American Society for Engineering Education Annual Conference & Exposition Copyright  2002, American Society for Engineering Education supports research into fast protection and reconfiguration of warship electrical systems, projects funded by the US Navy. Instead of its historical analog interface, the TNA gets updated to include digital generation and control of faults, a power electronic implementation of them, and automated instrumentation for a greater data collection and analysis capability. The Navy lacks (but really needs) these capabilities in its network of university research partners. In the course of installing, upgrading, and operating the TNA, it became a unique and powerful tool to teach undergraduate students the fundamentals of network operation and protection and to give them a vehicle for learning hands-on design of digital design methods and realistic behavior of electric power systems. Undergraduate involvement proved the norm from the very beginning. The TNA arrived on campus in a disassembled state, so the first project logically became assembly and testing. Ron Nelson, hired as a project engineer, performed most of the work. A team of three undergraduate students tested the TNA and documented its operation. The same team characterized the impedances of the major elements of the TNA, such as its transmission line segments. When they finished, the TNA was ready for its first projects, accomplished through undergraduate design work, to create the capabilities that the Navy needs. Figure 1. Transient Network Analyzer System Description The TNA is a small configurable electric power system. It has four tap selectable line segments and two source segments. A photograph is shown in Figure 1. Proceedings of the 2002 American Society for Engineering Education Annual Conference & Exposition Copyright  2002, American Society for Engineering Education A typical configuration is shown in Figure 2. The TNA operates at a nominal 120V / 208 V three phase. Each line segment has voltage and current instrumentation: (current transformers (CT) and potential transformers (PT). It has mechanical circuit breakers with both manual control and remote control logic. The circuit connections are all done with patch cables, so many configurations and measurement taps are possible. All line models are currently single pi. Connected to the TNA is a rack of state of the art protective relays donated by Schweitzer Engineering Laboratories, shown in the rack at the left side of Figure 1. These components allow implementation and testing of a wide variety of standard protection schemes. The next round of improvements will include multiple pi section line models and fast-acting solid state circuit breakers.