A New Transient Frequency Acceptability Margin Based on the Frequency Trajectory
When the electric power system is disturbed, the transient frequency deviation may be large and harmful to its stable operation, especially in some small power systems. However, there is a lack of transient frequency acceptability margin (TFAM) which could be directly used by dispatchers. In this paper, a new TFAM is proposed based on the transient frequency acceptability index (TFAI). First, based on the frequency trajectory and the philosophy of “different weights to the different frequency offset levels”, a new TFAI is proposed combined with frequency thresholds and time duration limits. The effectiveness of the TFAI is verified, and the critical acceptable disturbance is determined by using the TFAI. Then, a new TFAM is proposed based on the critical acceptability disturbance. The proposed TFAM can quantitatively describe the distance of the operation point from the critical frequency acceptability point, and distinguish the transient frequency acceptability of different disturbances. Finally, with different simulations, the effectiveness and applicability of the proposed TFAM are verified. The TFAM can be used for disturbances with single-parameter and multiple parameters.