Online parameter identification of generator motion equation based on PMU and slow-varying power

Since the mechanical power of generator cannot be directly measured and the electromagnetic parameters vary greatly due to different dynamic processes, the parameters of the motion equation cannot be accurately identified in the integrated parameter identification of generator set. The concept of slow-varying power is proposed, and the parameters of generator motion equation are identified independently based on PMU(Phase Measurement Unit) data. Firstly, the motion equation of generator is transformed so that the measured electromagnetic power is composed of slow-varying power and fast-changing power, in which the slow-varying power is composed of unmeasurable mechanical power and constant power, and the fast-chan-ging power is expressed by the motion parameters to be identified and the measurable rotating speed. Then, a low-pass filter is used to obtain the slow-varying power curve from the measured electromagnetic power, so as to transform the motion equation with unmeasurable variables into the identifiable equation with the parameters to be identified as the unknown quantities. The practical application results show that the proposed method can reduce the identification errors caused by not considering the variation of mechani-cal power in parameter identification or considering the linear relationship existing between the variation of mechanical power and the deviation of rotating speed. © 2020, Electric Power Automation Equipment Press. All right reserved.