An investigation of automatic generation control for an isolated power system

Hicks, Glenn V.(Glenn Victor) (1997) An investigation of automatic generation control for an isolated power system. 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 (10MB) [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

For the Newfoundland and Labrador Hydro (NLH) Energy Management System, the Automatic Generation Control (AGC) process performs the task of adjusting system generation to meet the load demand and of regulating the large system frequency changes. A result of the mismatches between system load and system generation, and system frequency and the desired value of 60 Hz is the accumulation of time error. Present AGC schemes used to combat this problem utilize a static, linear system response characteristic (SRC) to model the actual variable, non-linear system response to frequency deviations. For interconnected power systems, the AGC control signal is determined from the sum of the tie-line power interchange between interconnected systems and the system frequency deviation weighted by a bias factor, which is the SRC approximation. For an isolated power system, such as the NLH system, the control signal relies entirely on the weighted frequency deviation. Thus, the approximation of the SRC becomes increasingly important in the AGC process of an isolated power system. -- Current industry practice is to select the AGC bias factor based on the SRC and the annual peak load. This bias value then remains constant throughout the year. The use of a variable or dynamic value that is continuously changing throughout the year based on the system load and on-line generation can better approximate the SRC, and result in improved frequency regulation. Past research in this area has focused on the use of a variable bias factor in the AGC process of interconnected power systems. In this thesis, various methods for the calculation of a variable bias factor for use in an isolated power system are presented. Results show that by varying the bias factor in response to changes to the on-line generation (megawatt output and network configuration), improved frequency regulation, and hence a decrease in accumulated time error, can be realized. -- This thesis presents an investigation of the Automatic Generation Control process for an isolated power system. Using computer simulation techniques, a detailed model of the NLH Power system was implemented and tested using the load demand as input. The effect of a variable bias factor was investigated for various operating conditions, and compared to the presently used static value. Based on a set of performance indices, including the accumulated time and unit control errors, a control scheme was determined that provided improved frequency regulation in an isolated power system.

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