Bai Feng

Analysis and Study of Resonance Monitoring and Suppression Strategies of EHV Main Transformer

Analysis of waveforms recorded at the site is made with the interferences such as excitation current, etc. excluded, on the basis of analysis of Extra-high Voltage(EHV) main transformer resonance mechanism and via inputting all previous resonance data by using the accuracy and reliability of electromagnetic transient simulation verification and monitoring methods, corresponding figure topology analysis function is configured according to monitoring result and is used to analyze the cause and condition of resonance. Resonance monitoring methods are put forward in combination of Hilbert-Huang Transform (HHT) and peaking pulse time interval and are used to judge the occurrence and mode of resonance. According to the components and harmonic content of monitored main harmonics, the resonance class of main transformer is defined automatically, multi-stage resonance prewarning, slight resonance reliable signaling and warning of background, direct action on series compensation control and protection system after heavy resonance exceeding limits are achieved, and the safety of capacitor is protected with resonance removed at the same time, on the basis of parameter setting, based on commissioning and decommissioning methods for series compensation and the output magnitude of wind generation set at load side by using root-mean-square algorithm. At the same time, automatic series compensation recommissioning and permanent lockout function of many times of heavy resonances are added at fixed time sections, automatic commissioning and switching of series compensation are realized, the occurrence of secondary resonance is avoided, and the safe and steady operation of EHV main transformer resonance is guaranteed effectively.