Research on weak point location methods for oscillations in new energy power systems

Abstract

To mitigate the impact of oscillations on new energy power systems， it is crucial to assess the system stability state online and identify weak points susceptible to oscillations for proactive measures. To achieve this， two methods for locating weak points in new energy power systems are proposed， each from the perspectives of frequency domain characteristics and time-domain responses of the ports. The frequency domain method involves evaluating the system’s stability state based on the impedance characteristics of the ports at new energy substations， pinpointing weak substations according to the magnitude of the real part of the impedance at each substation. The time-domain method involves actively injecting a wideband small disturbance signal and utilizing the HHT （Hilbert-Huang transform） to analyze the current response at each port of new energy substations. Damping ratios of weak modes are extracted， and weak substations are located based on their magnitudes. The effectiveness of these location methods is validated using a small-scale new energy system composed of three wind farms. The results indicate that both methods accurately identify weak points in the system oscillations.

Keywords

• new energy power system
• weak point location for oscillation
• frequency-domain
• time-domain
• hilbert-huang transform