20-03-2014, 12:38 PM
EFFECT OF POWER QUALITY ON SHIP’S POWER SYSTEM
EFFECT OF POWER QUALITY.docx (Size: 289.43 KB / Downloads: 14)
Abstract:
This paper gives a brief overview of the effect of power quality on ship’s power system. Power Quality (PQ) has become an important concern for ship electric systems. Thus, deviations of voltage from nominal values and wave-shapes could cause several malfunctions, interruption or even damages of onboard equipment and systems .
INTRODUCTION
Power quality is a term referring to a wide variety of disturbances in electric networks. It can cause several malfunctions, interruption or even damages of equipment and systems. Considering the advent of All Electric Ship
Therefore, this paper aims primarily at making a coherent description and classification of the PQ phenomena (causes, consequences, characteristic parameters etc) occurring onboard highlighting their significance in the successful accomplishment of vessel missions.
From a certain point of view, PQ phenomena can be classified into two main categories, i.e.
(a) Steady-state phenomena which have inherent periodicity and they are repeated on almost constant basis without significant changes (e.g. there is no decaying mechanism), such as harmonics and unbalance, while there is also a stochastic parameter included in certain cases like notching, flickering etc.
(b) Transient-state phenomena, which are of limited duration and they are characterized by significant changes (there is definitely a decaying mechanism), such as spikes and transients like dips, swells.
OTHER POWER QUALITY ISSUES
Power frequency variations, one must note that power system frequency is related to the rotational speed of the generators on the system which depends on the balance between the load and the capacity of the available generation. When this dynamic balance changes, e.g. during starting-up of large power motors like those of thrusters, small changes in frequency occur. In isolated power systems, as the ones in ships, problems occur when the governor response to abrupt load changes is not adequate to regulate within the bandwidth required by frequency sensitive equipment .
CONCLUSION
Power supply interruptions are an
important aspect of power quality and it must be included in a monitoring survey with all the relevant details (cause and duration) in order to evaluate the performance of the electric system, identify the weak components, apply enforcements and select appropriate power quality mitigation equipment.