The Mechanism Research of Low Frequency Oscillation Occurred in Hebei Power Grid of China

The An-Bao line low frequency oscillation occurred in Hebei province power grid of China was analyzed in this paper. The oscillation modes of Hebei power grid were obtained by eigenvalue analysis. The An-Bao line oscillation frequency was obtained though applying Prony method to analyze field data. Simulation results indicate that the An-Bao line low frequency oscillation cannot be interpreted by negative damping theory. The resonance mechanism of low frequency oscillation was put up in this paper, which can interpret the An-Bao line low frequency oscillation. The probability of power disturbance of prime mover is researched in this paper to support the resonance mechanism. The coupling model between thermodynamic system of plant and power system was set up using MATLAB. The simulation results indicate that power system low frequency oscillations of resonance mechanism might be caused by the disturbance of control valve, when its frequency is close to the power system natural oscillations frequency. If the speed-droop of governing system is too small in some running point, control valve disturbance with natural frequency of power system can be induced by speed deviation.