Variable Evaluation and Optimal Placement of STATCOM in Test Bus Systems

This paper presents the mathematical steady-state modelling of Static Synchronous Compensator (STATCOM) for voltage control of a bus and hence the variable of the controller. MATLAB programs have been developed for implementation of a few models of STATCOM. In this regard, Newton-Raphson load flow algorithm has been modified for incorporating models of STATCOM in some standard test bus systems. IEEE 5-bus system and IEEE 14-bus system are considered. Load sensitivity factors, which are defined as the effect of load on power system variables, are evaluated for load buses of the above mentioned test bus systems by increasing load on each load bus to 140% of base case value. Since load change affects node voltage, hence node voltage load dependency factor (NVLDF) of all buses are evaluated for finding optimal location of STATCOM. Thus this paper aims at evaluation of variable of STATCOM and finding optimal location for the same

Epidemiology of Hepatitis B Virus (HBV)

HBV infection is endemic in Singapore. The majority of infection is subclinical and infection occurs continuously in all age groups, about 50% of the population being infected by 40-49 and 100% in the > 60 age group. The frequency of HBsAg is highest in the <12 age group. HBV is responsible for about 50% of acute viral hepatitis in Singapore. Besides horizontal transmission, subclinical HBV infection also occurs vertically and perinatally. Maternal-infant transmission is most likely to occur in HBeAg positive mothers and the majority of transmission occurs during the perinatal period. Perinatal transmission contributed about a quarter of the HBsAg carrier rate in children one year of age. HBsAg carrier status is not only strongly associated with primary liver cancer but also in premalignant conditions of chronic hepatitis and non alcoholic cirrhosis. There is a direct relationship between carrier status and primary liver cancer incidence in both males and females of the three ethnic groups of Chinese, Malay and Indians. There are some indirect evidence to suggest that HBV infection by perinatal transmission may be more important than by acute clinical infection in subsequent development of primary liver cancer