New Alternatives to Mitigate Nuisance Tripping of PWM ASDs under Capacitor-Switching Transients (CSTs)

J.L. Durán-Gómez (Mexico)


Power quality, capacitor switching-transient and ASDs


Utility capacitor-switching transients (CSTs) are responsible for numerous nuisance tripping of PWM adjustable speed drives (ASDs) and result in costly down times. During a CST event, the dc-link voltage of the ASD can momentarily rise to greater than 1.3 p.u. resulting in nuisance tripping. In this paper, new alternatives are discussed and explored as approaches to reduce the susceptibility of PWM ASDs to CSTs. In a first approach, it is introduced a transformer in the series path of the dc-link power flow of an ASD. In the secondary winding of the transformer, a damping resistor is connected in combination with a switching power semiconductor to damp the CST. In a second approach, the oscillatory energy produced by the resonance condition of a typical CST event is electronically absorbed by an electronic charging converter. This converter, which is a typical buck-boost power structure topology, is used to charge a super-capacitor during the transient condition. The proposed approaches are explored to demonstrate the feasibility of a method of damping the CST’s energy, and charge a super-capacitor (ultra-capacitor) by taking advantage of the oscillatory energy produced during the CST.

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