This paper suggests improving the quality and performance of electrical grid by using Four
Chopper circuit in the DC –Link of the variable speed drive system with 12 pulse rectifier.
In addition, it analyses the effects on the ripple factor for bot
h current and voltage in DClink
and improving the system's stability.
For this study a variable speed drive system has been simulated and designed with the
proposed chopper and 12 pulse rectifiers. In order to confirm the ability of Using four -
quadrant chopper with rectifier circuits and its ability to improve the stability of the power
systems, a variable speed system has been simulated
Finally, A discussion of the results was introduced. The giving results show the advantages
of using the proposed chopper with variable speed drive systems.
This research aimed to study some chemical characteristics of rainwater in the region
located at the East of Baniyas area the coastal region of Syria . Baniyas area contain
complex of industrial facilities including oil refinery, electrical power g
eneration station
and oil transportation. pH values, concentration of trace metals (Pb, Cu, and Cd) and major
ions (Ca2+, Mg 2⁺, Na⁺, NH₄⁺, K⁺,SO₄2-, NO3⁻, Cl⁻, F⁻) were determined during the period
from October 2012 to May 2013.
Samples were collected from 15 sites differ in distances from the emissions sources.
Most of samples have normal pH value. The pH values decreased while the concentration
of SO₄2-, NO3⁻, and trace metals Pb, Cu, Cd increased significantly by getting closer to
emission source up on 2500m. The changes of the chemical characteristics of rainwater
were significant.
