Mechanistic analysis of forced oscillations arising from suboptimal static characteristics of speed control systems

• Published in: 2023 3rd International Conference on Electrical Engineering and Mechatronics Technology (ICEEMT) pp. 310 - 316
• Main Authors: Wang, Lichao, Yu, Yongjun, Liu, Qiujiang, Cao, Guotao, Sun, Binghan, Li, Mengtong
• Format: Conference Proceeding
• Language: English
• Published: IEEE 21.07.2023
• Subjects: Forced oscillation; Frequency modulation; Power grids; Renewable energy sources; Speed regulation system; Static characteristics; Thermal force; Thermal variables control; Valves; Velocity control
• DOI: 10.1109/ICEEMT59522.2023.10262948

With the operation of AC/DC hybrid power grids and the large-scale integration and consumption of renewable energy, the power grid has experienced multiple low-frequency power oscillations and sub/ultra synchronous oscillations, seriously affecting the safe operation of the power grid. This article derived the mechanism of forced oscillation, the relationship between mechanical power disturbance and sudden changes in valve flow rate, as well as the static characteristics of the speed control system; The mechanism of forced oscillation induced by the imperfect static characteristics of the steam turbine speed control system has been derived. The frequency difference valve position curve function of the unit's primary frequency regulation under the variable unequal rate setting was proposed, which resulted in too small local speed unequal rate and unsatisfactory static characteristics of the turbine, leading to forced oscillation. Finally, taking a forced oscillation accident of a thermal power unit as an example, the oscillation type and disturbance source were identified, and the effectiveness of the conclusion was verified.