Comparative study of intensive pulse load impact on active and passive rectification system in MVDC ship power generation unit

Abstract

The rectifier plays a key role in connecting generation units to a medium voltage direct current (MVDC) bus on all electric ship power systems, where the rectification systems provide power continuation warranty including power quality criteria in order to meet standard requirements. Active rectifiers are able to present distinguished benefits over passive rectifiers such as: regulation, dynamic response to load change, output voltage ripple, input current total harmonic distortion (THD), power factor correction, and wave factor. On the other hand, passive rectifiers can demonstrate simplicity. They require fewer components resulting in a lower cost, reduced maintenance and installation effort. This paper purveys a thorough quantified and qualified analysis of neutral-point-clamped (NPC) and three-phase diode rectifiers as active and passive rectification modules, respectively, when they supply intensive pulse loads. The three-phase diode rectifier without line filter inductor and with output filter capacitor is directly connected to a synchronous generator including an automatic voltage regulator (AVR) that regulates the generator and the rectifier output voltage in the first two scenarios, respectively. In the third scenario, the NPC rectifier that is able to regulate the output voltage independent of input voltage alterations is demonstrated by a three-phase source with variable output amplitude. All three cases will be simulated thoroughly to validate the steady-state and transient performance of these test scenarios, while in each case the rectifier's output supplies an intensive pulse load.