الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
Voltage dips are probably the most important power quality problem, especially for and commercials customers having sensitive electrical equipment. Examples of . ICOSitive equipment are adjustable speed drives and computers. Often disconnection •poduction lines caused by voltage dips can generate large financial losses.
are short duration reductions in the RMS voltage. Motor starting and . nnsfonner energizing cause voltage dips. Most severe dips are due to short-circuit and 8th faults.
Statistical dip characterization of power networks is essential to decide about mitigation methods as well as for regulatory purposes. Statistics on voltage dip events may be obtained by using monitoring of the power supply. Monitoring is expensive and requires long monitoring periods. The alternative is stochastic assessment of voltage dips. Stochastic assessment of voltage dips combines stochastic data concerning the fault likelihood with deterministic data regarding the remaining voltages during the fault.
In this thesis, stochastic assessment of voltage dips is used to characterize the dip performance of a simplified IEEE 14-bus test system. The software package MatlablSimulink is used for the simulations. The theoretical background for calculating the remaining voltages during a fault is developed. Balanced and unbalanced dips are considered. The effect of power transformers between the fault point and the observation bus is taken into account. A matrix notation is introduced in order to describe the dip magnitudes for all buses due to all possible faults. The resulting dip-matrix is then combined with the fault occurrence rates corresponding to the fault positions. This results in dip ftequencies for each bus. Site indices are calculated for each bus and system indices are calculated for the system as a whole. Results are presented in tables, graphs and diagrams.
Finally, conclusions are included and future research recommendations are identified