INVESTIGATION OF NONLINEAR TIE LINE BIAS CONTROL OF INTERCONNECTED POWER SYSTEMS.

Present Automatic Generation Control schemes utilize a linear tie-line bias characteristic. Due to nonlinearities in the connected load and governor dead bands the actual system response characteristic is nonlinear. Therefore, a linear tie-line bias characteristic does not match the actual system response characteristic. This mismatch causes unnecessary fuel consumption and increased wear and tear on generators. This paper presents a study to: (1) determine the response characteristic for a typical power system; and (2) to evaluate the effect of implementing a nonlinear tie-line bias characteristic. This study was performed utilizing the UMC (University of Missouri-Columbia) hybrid simulator to simulate a typical power system including governor dead band, frequency, and voltage sensitivity of loads. Results of this study are determined by comparing 24-hour dispatch runs for a linear tie-line bias with a nonlinear tie-line bias control characteristic matching the system natural response characteristic. Quantitative system performance indices are developed to evaluate the relative system performance.