The increases in power network and weak tie-line have led power system oscillation problems. To improve the oscillatory stability, installing the power system stabilizer (PSS) with optimal allocation is considered due...The increases in power network and weak tie-line have led power system oscillation problems. To improve the oscillatory stability, installing the power system stabilizer (PSS) with optimal allocation is considered due to excessive cost. This paper recommends the suitable PSS locations by using eigenvalue analysis and participation factor to enhance the system oscillation damping. The effects of installed PSSs in damping local and inter-area modes of oscillations are confirmed through time domain simulation results. The effectiveness of proposed approach is tested and validated on MEPE test system. Robustness of stabilizers against dynamic response of generator speed deviation, rotor angle deviation, and response of mechanical power are observed to access the performances of PSSs.展开更多
Background:Transitional economies in Southeast Asia—a distinct group of developing countries—have experienced rapid urbanization in the past several decades due to the economic transition that fundamentally changed ...Background:Transitional economies in Southeast Asia—a distinct group of developing countries—have experienced rapid urbanization in the past several decades due to the economic transition that fundamentally changed the function of their economies,societies and the environment.Myanmar,one of the least developed transitional economies in Southeast Asia,increased urbanization substantially from 25%in 1990 to 31%in 2019.However,major knowledge gaps exist in understanding the changes in urban land use and land cover and environment and their drivers in its cities.Methods:We studied Yangon,the largest city in Myanmar,for the urbanization,environmental changes,and the underlying driving forces in a radically transitioned economy in the developing world.Based on satellite imagery and historic land use maps,we quantified the expansion of urban built-up land and constructed the land conversion matrix from 1990 through 2020.We also used three air pollutants to illustrate the changes in environmental conditions.We analyzed the coupled dynamics among urbanization,economic development,and environmental changes.Through conducting a workshop with 20 local experts,we further analyzed the influence of human systems and natural systems on Yangon’s urbanization and sustainability.Results:The city of Yangon expanded urban built-up land rapidly from 1990 to 2000,slowed down from 2000 to 2010,but gained momentum again from 2010 to 2020,with most newly added urban built-up land appearing to be converted from farmland and green land in both 1990–2000 and 2010–2020.Furthermore,the air pollutant concen-tration of CO decreased,but that of NO_(2)and PM_(2.5)increased in recent years.A positive correlation exists between population and economic development and the concentration of PM_(2.5)is highly associated with population,the economy,and the number of vehicles.Finally,the expert panel also identified other potential drivers for urbanization,including the extreme climate event of Cyclone Nargis,capital relocation,and globalization.Conclusions:Our research highlights the dramatic expansion of urban land and degradation of urban environment measured by air pollutants and interdependent changes between urbanization,economic development,and environmental changes.展开更多
文摘The increases in power network and weak tie-line have led power system oscillation problems. To improve the oscillatory stability, installing the power system stabilizer (PSS) with optimal allocation is considered due to excessive cost. This paper recommends the suitable PSS locations by using eigenvalue analysis and participation factor to enhance the system oscillation damping. The effects of installed PSSs in damping local and inter-area modes of oscillations are confirmed through time domain simulation results. The effectiveness of proposed approach is tested and validated on MEPE test system. Robustness of stabilizers against dynamic response of generator speed deviation, rotor angle deviation, and response of mechanical power are observed to access the performances of PSSs.
基金supported by the National Aeronautics and Space Administration(NASA)(Grant numbers:NNX15AD51G,80NSSC20K0740).
文摘Background:Transitional economies in Southeast Asia—a distinct group of developing countries—have experienced rapid urbanization in the past several decades due to the economic transition that fundamentally changed the function of their economies,societies and the environment.Myanmar,one of the least developed transitional economies in Southeast Asia,increased urbanization substantially from 25%in 1990 to 31%in 2019.However,major knowledge gaps exist in understanding the changes in urban land use and land cover and environment and their drivers in its cities.Methods:We studied Yangon,the largest city in Myanmar,for the urbanization,environmental changes,and the underlying driving forces in a radically transitioned economy in the developing world.Based on satellite imagery and historic land use maps,we quantified the expansion of urban built-up land and constructed the land conversion matrix from 1990 through 2020.We also used three air pollutants to illustrate the changes in environmental conditions.We analyzed the coupled dynamics among urbanization,economic development,and environmental changes.Through conducting a workshop with 20 local experts,we further analyzed the influence of human systems and natural systems on Yangon’s urbanization and sustainability.Results:The city of Yangon expanded urban built-up land rapidly from 1990 to 2000,slowed down from 2000 to 2010,but gained momentum again from 2010 to 2020,with most newly added urban built-up land appearing to be converted from farmland and green land in both 1990–2000 and 2010–2020.Furthermore,the air pollutant concen-tration of CO decreased,but that of NO_(2)and PM_(2.5)increased in recent years.A positive correlation exists between population and economic development and the concentration of PM_(2.5)is highly associated with population,the economy,and the number of vehicles.Finally,the expert panel also identified other potential drivers for urbanization,including the extreme climate event of Cyclone Nargis,capital relocation,and globalization.Conclusions:Our research highlights the dramatic expansion of urban land and degradation of urban environment measured by air pollutants and interdependent changes between urbanization,economic development,and environmental changes.
