Mini-hydro systems using induction generators

Eaton, Norris William (1997) Mini-hydro systems using induction generators. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (30MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

This study has focused on developing and documenting a systems approach toward modern electrical design that minimizes the cost of building and operating a grid-connected mini-hydro plant. The thesis applied innovative electrical design to reduce capital costs, lower operating costs, increase efficiency, and maximize revenue. This was achieved by following a multi-diciplined engineering approach, selecting a standard three-phase squirrel cage induction motor as the grid-connected induction generator, automating and remotely controlling the plant to eliminate the cost of a full-time operator, and incorporating an innovative diagnostic expert system to quickly assist in isolating the cause of a plant shutdown. -- It was clearly established that a significant reduction in the capital cost of electrical equipment is achievable if the squirrel cage induction motor is used as the induction generator. The "off-the-shelf" induction motor and standard solid-state motor starter are relatively inexpensive in comparison to custom induction or synchronous generators. Since standard three-phase, 575V induction motors have ratings less than 200 kVA, the focus was on grid connected mini-hydro developments with an installed capacity of less than 200 kVA. Stand-alone plants, similar to those found in isolated communities and mining sites, were not considered. -- Knowing when to use an induction generator, and the type of control philosophy to implement, is based on the assumption the electrical designer has an understanding of the complete mini-hydro development process, consequently the thesis also covered the general design of mini-hydro systems. While this is not an exhaustive treatment of the subject matter, it is an indication of the level of understanding required for the electrical design. -- The thesis documents the theory, performance characteristics, and design considerations associated with an induction generator, in an effort to evaluate the appropriateness of installing the induction generator at a grid-connected location. Also, a method was presented for selecting the standard squirrel cage induction motor to use as an induction generator. Induction generator protection requirements, utility protection, and mechanical systems protection were investigated, and modern solutions proposed. The PLC was used to automate the plant and cost effective remote control options were explored. An innovative and novel diagnostic expert system was developed and demonstrated. Finally, the systems approach and documentation of modern electrical design and operating methods was applied to a practical example, a 150 kW installation proposed for Nipper's Harbour.

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