Mitigating ferroresonance in coupling capacitor voltage transformers with ferroresonance suppressing circuits

Abstract

In order to restrain ferroresonance in coupling capacitor voltage transformers (CCVT), two kinds of ferroresonance suppression circuits (FSCs) , are proposed in this paper: the resonant type, the fastsaturation reactor type which are connected to secondary side of CCVTs. Frequency domain analyses, for voltage ratio magnitude, are carried out for CCVTs to obtain preferable FSC. Furthermore, using surge suppressors such as metal oxide varistors (MOV) to improve the performance of the FSCs is investigated. Time domain simulations demonstrate that ferroresonance can be cleared in few cycles in presence of FSCs. The Electromagnetic Transients Program (EMTP) is used for modeling and fine-tuning the FSCs.

A review of ferroresonance in capacitive voltage transformer

“…The filter exhibits a high impedance at the fundamental frequency. In contrast, the impedance of the active FSC gradually approaches the resistance of the damping resistor as the frequency deviates from the fundamental frequency . The results of the simulation for passive and active FSC are shown in Fig.…”

“…Ferroresonance suppression methods including saturable‐reactor‐type FSC, fundamental‐frequency‐blocking filter type FSC, and electronic type FSC have been studied and their performances to suppress ferroresonance have been investigated in [15,36,38,39,51,52]. The frequency domain analysis showed that the saturable‐reactor type FSC is more desirable than resonance‐filter type FSC because the CVT frequency response is adversely affected by the resonance filter, causing error in the output signal in the case of higher order harmonics or fast changes in the system voltage . On the other hand, the time domain simulation showed that electronic type FSC with a damping resistor is more effective to damp out ferroresonance than other methods .…”

“…The authors in Ref. also reported that the addition of a surge arrester will significantly reduce the damping time and limit the overvoltage that is experienced in CVT during the first cycle. The impacts of active FSC, passive FSC, and over voltage protection devices for fast CVT ferroresonance suppression have been studied in Ref.…”

Ferroresonance Study on the VT in the Karoon 4 Power Plant 400 kV GIS Substation

“…Hyundai Reports (2011) and Jacobson (2003) outbreak of ferroresonanc has some signs like permanent over voltage with vast amplitude as phase to phase or phase to ground, permanent over current with vast amplitude, shifting voltage zero point, increasing temperature of voltage transformer, continual increasing of the noise altitude of trans formers and reactors, damaging electrical equipment's such as capacitor banks and CVT because of increasing the thermal effect or breakage of dampers of the protective equipment's. Therefore some limitations should be applied to parameters of systems to avoid occurrence of undesirable phenomena like these (Qing and Yufeng, 2008;Shahabi et al, 2009). All of the studies have been simulated by EMTP-RV software.…”

Modeling of Ferro-resonance on the VT of GIS substation

“…Therefore some limitations should be applied to parameters of systems to avoid occurrence of undesirable phenomena like these. [4], [5]. All of the studies have been simulated by EMTP-RV software.…”