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Surge Arresters
Published in Martinez-Velasco Juan A., Power System Transients, 2017
Juan A. Martinez-Velasco, Ferley Castro-Aranda
Overvoltages caused by ferroresonance: Ferroresonant overvoltages result when a saturable inductance is placed in series with a capacitance in a lightly damped circuit. This circuit topology can result when one or two transformer phases are disconnected from the source. The capacitance may be provided by overhead lines, underground cables, the internal capacitance of the transformer windings, or by shunt capacitor banks [60,66]. Overvoltage magnitudes depend on the transformer primary winding connection and the amount of capacitance present compared to the transformer characteristics. For transformers with ungrounded primary connections, ferroresonant overvoltages can easily exceed 3–4 pu [67,68]. Short underground cable lengths may be sufficient to cause crest voltages of this severity [69]. Internal transformer capacitance may also suffice to cause ferroresonance in ungrounded primary transformers and banks. The ferroresonant over-voltage can persist for as long as the open-phase condition, which may be intentional or due to the operation of a protective device such as a fuse. Single-phase protective devices should be avoided if their operations can result in an open-phase condition present for a long period of time.
Distribution Short-Circuit Protection
Published in Leonard L. Grigsby, and Distribution: The Electric Power Engineering Handbook, 2018
Ferroresonance usually occurs during manual switching of single-pole switching devices (where the load is usually an unloaded transformer). It is less common for ferroresonance to occur downstream of a single-phase protective device that is operating due to a fault. The reason for this is that if there is a fault on the opened phase, the fault prevents an overvoltage on the opened phase. Also, any load on the opened section helps prevent ferroresonant overvoltages. Because ferroresonance will be uncommon with single-phase protective devices, it is usually not a major factor in protective device selection. Still, caution is warranted on small three-phase transformers that may be switched unloaded (especially at 24.94 or 34.5 kV).
Short-Circuit Protection
Published in T. A. Short, Electric Power Distribution Handbook, 2018
Ferroresonance usually occurs during manual switching of single-pole switching devices (where the load is usually an unloaded transformer). It is less common for ferroresonance to occur downstream of a single-phase protective device that is operating due to a fault. The reason for this is that if there is a fault on the opened phase, the fault prevents an overvoltage on the opened phase. Also, any load on the opened section helps prevent ferroresonant overvoltages. Because ferroresonance will be uncommon with single-phase protective devices, it is usually not a major factor in protective device selection. Still, caution is warranted on small three-phase transformers that may be switched unloaded (especially at 24.94 or 34.5 kV).
Simulation and experimental research on methods to suppress ferroresonance in potential transformers
Published in Journal of Control and Decision, 2018
Hongwen Liu, Ke Wang, Junhui Zhao, Hao Li, Shijin Tian
In Figure 3, a three-phase circuit with grounded-wye connection PTs is presented. The circuit consists of three-phase source (EA, EB and EC), a phase-to-ground capacitor (C0) and PTs. Transient electromagnetic disturbances, such as ones caused by lightning, single-phase grounding, disconnection faults, reclosing and transfer overvoltage, can induce the ferroresonance. The neutral point displacement voltage U0 will become non-zero and can be calculated by:
Elimination of Chaotic Ferroresonant Oscillations Originated from TCSC in the Capacitor Voltage Transformer
Published in IETE Journal of Research, 2018
Ataollah Abbasi, Seyed Hamid Fathi, Amin Mihankhah
Ferroresonance is an electrical complex nonlinear event, which can create thermic and insulation damage in transmission and distribution systems. It may be initiated with contingency switching action, lightning, routine switching, no load conditions, series compensation, and load shedding [1–3]. This phenomenon contains numerous modes with different frequencies such as fundamental frequency, sub-harmonic, quasi alternative, and chaotic modes [4,5]. The sudden transfer or jump from one steady state to another is operated by a disturbance, switching action or gradual changes in amount of a parameter.