Improved system AGC performance with arc furnace steel mill loads

Area control error (ACE) filtering techniques and load frequency control (LFC) logic were developed and implemented into Texas Utilities Electric Company's (USA) AGC software to address the AGC performance problem attributed to arc furnace steel mill loads. The project goal was to reduce power plant fuel cost and operating expenses by reducing the unnecessary movement of units responding to these nonconforming loads through AGC. Online field testing was conducted by alternating between the original AGC software and the modified AGC software. A total of 61 days under the old AGC system and 39 days under the new AGC system were used for analysis. Under the new AGC system, the overall average number of pulses per control hour sent to units on control was reduced by 27%, and the overall average number of pulse reversals per control hour sent to individual units on control was reduced by 42%. Analysis of field test data indicates convincingly that the new AGC system reduces unit pulse reversals per control hour.