Visual real-time monitoring is the premise of low frequency oscillation control in power grids. This paper showed a visual method for the control center of power grids to monitor low frequency oscillation. It processe...Visual real-time monitoring is the premise of low frequency oscillation control in power grids. This paper showed a visual method for the control center of power grids to monitor low frequency oscillation. It processed the PMU real-time data with incomplete S-transform, and converted the waveforms to two-dimensional time-frequency figures which showed the initial time, frequency and amplitude of each low frequency oscillation mode directly. GPU was used to show figures and calculate FFT with the purpose of improving calculation efficiency. The results of practical cases show that the real-time characters of low frequency oscillation can be identified availably by this visualization real-time monitoring method which is helpful and suitable for practical application.展开更多
The chemical kinetics of hydrogen atom(H-atom)abstraction reactions from norbornadiene(NBD)by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2)),and the unimolecular reactions of three NBD derived radicals,were studied th...The chemical kinetics of hydrogen atom(H-atom)abstraction reactions from norbornadiene(NBD)by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2)),and the unimolecular reactions of three NBD derived radicals,were studied through high-level ab-initio calculations.The geometries optimization and vibrational frequencies calculation for all the reactants,transition states,and products were obtained at the M06-2X/6-311ttG(d,p)level of theory.The zeropoint energy(ZPE)corrected potential energy surfaces(PESs)were determined at the QCISD(T)/cc-pVDZ,TZ level of theory with basis set corrections from MP2/cc-pVDZ,TZ,QZ methods for single point energy calculations.Conventional transition state theory(TST)was used for the rate constants calculations of H-atom abstraction reactions by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2))at temperatures from 298.15 to 2000 K,while the a-site H-atom abstraction reaction rate constant of NBD by OH radical has been obtained through variational transition state theory(VTST).The results show that the H-atom abstraction reactions from the α-carbon atom of NBD are the most critical channels at low temperatures.Total rate constants for H-atom abstraction reactions by OH radical are also the fastest among all of the reaction channels investigated at the temperature range from 298.15 to 2000 K.Rice-Ramsperger-Kassel-Marcus/Master Equation(RRKM/ME)has been used to calculate the pressure-and temperature-dependent rate constants for the unimolecular reactions of three related C7H7 product radicals which generated from H-atom abstraction reaction within temperature ranges of 300-2000 K and pressures of 0.01-100 atm.A combination of composite methods has been used to calculate the temperature-dependent thermochemical properties of NBD and related radicals.All the calculated kinetics and thermochemistry data can be utilized in the model development for NBD oxidation.展开更多
文摘Visual real-time monitoring is the premise of low frequency oscillation control in power grids. This paper showed a visual method for the control center of power grids to monitor low frequency oscillation. It processed the PMU real-time data with incomplete S-transform, and converted the waveforms to two-dimensional time-frequency figures which showed the initial time, frequency and amplitude of each low frequency oscillation mode directly. GPU was used to show figures and calculate FFT with the purpose of improving calculation efficiency. The results of practical cases show that the real-time characters of low frequency oscillation can be identified availably by this visualization real-time monitoring method which is helpful and suitable for practical application.
基金supported by the National Science and Technology Major Project(2017-Ⅲ-0004-0028/J2019-Ⅲ-0005-0048)NSFC(51976216)+1 种基金Sinopec Science and Technology Departmentthe High-Performance Computing(HPC)Center of Beihang University.
文摘The chemical kinetics of hydrogen atom(H-atom)abstraction reactions from norbornadiene(NBD)by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2)),and the unimolecular reactions of three NBD derived radicals,were studied through high-level ab-initio calculations.The geometries optimization and vibrational frequencies calculation for all the reactants,transition states,and products were obtained at the M06-2X/6-311ttG(d,p)level of theory.The zeropoint energy(ZPE)corrected potential energy surfaces(PESs)were determined at the QCISD(T)/cc-pVDZ,TZ level of theory with basis set corrections from MP2/cc-pVDZ,TZ,QZ methods for single point energy calculations.Conventional transition state theory(TST)was used for the rate constants calculations of H-atom abstraction reactions by five radicals(H,O(^(3)P),OH,CH_(3),and HO_(2))at temperatures from 298.15 to 2000 K,while the a-site H-atom abstraction reaction rate constant of NBD by OH radical has been obtained through variational transition state theory(VTST).The results show that the H-atom abstraction reactions from the α-carbon atom of NBD are the most critical channels at low temperatures.Total rate constants for H-atom abstraction reactions by OH radical are also the fastest among all of the reaction channels investigated at the temperature range from 298.15 to 2000 K.Rice-Ramsperger-Kassel-Marcus/Master Equation(RRKM/ME)has been used to calculate the pressure-and temperature-dependent rate constants for the unimolecular reactions of three related C7H7 product radicals which generated from H-atom abstraction reaction within temperature ranges of 300-2000 K and pressures of 0.01-100 atm.A combination of composite methods has been used to calculate the temperature-dependent thermochemical properties of NBD and related radicals.All the calculated kinetics and thermochemistry data can be utilized in the model development for NBD oxidation.
