The increasing penetration of renewable energy resources with highly fluctuating outputs has placed increasing concern on the accuracy and timeliness of electric power system state estimation(SE).Meanwhile,we note tha...The increasing penetration of renewable energy resources with highly fluctuating outputs has placed increasing concern on the accuracy and timeliness of electric power system state estimation(SE).Meanwhile,we note that only a fraction of system states fluctuate at the millisecond level and require to be updated.As such,refreshing only those states with significant variation would enhance the computational efficiency of SE and make fast-continuous update of states possible.However,this is difficult to achieve with conventional SE methods,which generally refresh states of the entire system every 4–5 s.In this context,we propose a local hybrid linear SE framework using stream processing,in which synchronized measurements received from phasor measurement units(PMUs),and trigger/timingmode measurements received from remote terminal units(RTUs)are used to update the associated local states.Moreover,the measurement update process efficiency and timeliness are enhanced by proposing a trigger measurement-based fast dynamic partitioning algorithm for determining the areas of the system with states requiring recalculation.In particular,non-iterative hybrid linear formulations with both RTUs and PMUs are employed to solve the local SE problem.The timeliness,accuracy,and computational efficiency of the proposed method are demonstrated by extensive simulations based on IEEE 118-,300-,and 2383-bus systems.展开更多
Objective To develop an efficient method for separating and purifying puerarin from the roots of Pueraria lobata.Methods Separation by fast centrifugal partition chromatography（FCPC）was processed with a biphasic sol...Objective To develop an efficient method for separating and purifying puerarin from the roots of Pueraria lobata.Methods Separation by fast centrifugal partition chromatography（FCPC）was processed with a biphasic solvent system composed of ethyl acetate-n-butanol-water（2：1：3）.The separation conditions were determined as follows：sample loading of 10 mg,flow rate of 2 mL/min,rotation speed of 2200 r/min,ascending mode,and detection wavelength of 254 nm.High speed countercurrent chromatography（HSCCC）was used as a comparative method with the rotation speed of 800 r/min,flow rate of 2.0 mL/min,and sample loading of 10 mg in tail-to-head mode.Results Puerarin was obtained by FCPC with a resolution of 0.90 and a purity above 99%,while a resolution below 0.50 and a purity below 90%by HSCCC.Compared with HSCCC,FCPC has the advantages with higher purity and better resolution.Conclusion FCPC is a powerful method to separate and purify puerarin.展开更多
基金supported by the National Key Research and Development Program of China under Grant 2018YFB0904500。
文摘The increasing penetration of renewable energy resources with highly fluctuating outputs has placed increasing concern on the accuracy and timeliness of electric power system state estimation(SE).Meanwhile,we note that only a fraction of system states fluctuate at the millisecond level and require to be updated.As such,refreshing only those states with significant variation would enhance the computational efficiency of SE and make fast-continuous update of states possible.However,this is difficult to achieve with conventional SE methods,which generally refresh states of the entire system every 4–5 s.In this context,we propose a local hybrid linear SE framework using stream processing,in which synchronized measurements received from phasor measurement units(PMUs),and trigger/timingmode measurements received from remote terminal units(RTUs)are used to update the associated local states.Moreover,the measurement update process efficiency and timeliness are enhanced by proposing a trigger measurement-based fast dynamic partitioning algorithm for determining the areas of the system with states requiring recalculation.In particular,non-iterative hybrid linear formulations with both RTUs and PMUs are employed to solve the local SE problem.The timeliness,accuracy,and computational efficiency of the proposed method are demonstrated by extensive simulations based on IEEE 118-,300-,and 2383-bus systems.
基金International Science and Technology cooperation project of Shanghai(No.12120701400,2012)
文摘Objective To develop an efficient method for separating and purifying puerarin from the roots of Pueraria lobata.Methods Separation by fast centrifugal partition chromatography（FCPC）was processed with a biphasic solvent system composed of ethyl acetate-n-butanol-water（2：1：3）.The separation conditions were determined as follows：sample loading of 10 mg,flow rate of 2 mL/min,rotation speed of 2200 r/min,ascending mode,and detection wavelength of 254 nm.High speed countercurrent chromatography（HSCCC）was used as a comparative method with the rotation speed of 800 r/min,flow rate of 2.0 mL/min,and sample loading of 10 mg in tail-to-head mode.Results Puerarin was obtained by FCPC with a resolution of 0.90 and a purity above 99%,while a resolution below 0.50 and a purity below 90%by HSCCC.Compared with HSCCC,FCPC has the advantages with higher purity and better resolution.Conclusion FCPC is a powerful method to separate and purify puerarin.
