1 Introduction The proposal of the concept of“New Power System”aims to illustrate the transform direction of the traditional power system,acting as the development core of the future new power grid.To achieve this,t...1 Introduction The proposal of the concept of“New Power System”aims to illustrate the transform direction of the traditional power system,acting as the development core of the future new power grid.To achieve this,the proposed strategic targets of“carbon neutralization and carbon peaking”must be implemented and insisted[1].The core feature of the new power system is that renewable energy plays a leading role and becomes the main source of energy supply,meanwhile,the goal of green energy utilization has also been put forward on the agenda.Green energy utilization includes two aspects,one is the exploitation and promotion of various green energy technologies,and the other is the digitalization of energy management.Under this trend,stochastic and fluctuating energy sources such as wind power and photovoltaic power replace deterministic controllable power sources such as thermal power,bringing challenges to power grid regulation and dispatching,as well as flexible operation.The large-scale integration of renewable energy and increasingly high proportion of power electronic equipment tend to bring about fundamental changes in the operation characteristics,safety control,and production mode of the power system.展开更多
To ensure wind turbine(WT)safe operations and improve the utilization rate of wind energy,effective evaluation of the operation state of the pitch system is critical.Therefore,a new method was proposed to evaluate the...To ensure wind turbine(WT)safe operations and improve the utilization rate of wind energy,effective evaluation of the operation state of the pitch system is critical.Therefore,a new method was proposed to evaluate the operation state of the pitch system of WT based on fuzzy comprehensive evaluation.Firstly,based on SCADA data,the working state of the pitch system under rated power state and power state of WT were analyzed.Secondly,through the analysis of characteristic parameters and physical mechanism of the pitch system,the consistency principle of characteristic parameters,the stability principle of power under rated state,and the stability principle of blade angle underpowered state were obtained.Next,based on the aforementioned principles,the evaluation indexes were established,and the fuzzy comprehensive evaluation method was used to establish the operation state evaluation model of the pitch system under rated power state and under power state of the WT.Finally,an example was provided to verify the effectiveness of the method.The evaluation model established in this study can be used as a technical reference for the online monitoring of WT pitch systems to ensure the safe and stable operation of WTs.展开更多
Of the 700,000 people in the United States who experience a new or recurrent stroke each year,more than 500,000 survive(American Stroke Association,2007)[1]. Occupational therapy practitioners are critical rehabilitat...Of the 700,000 people in the United States who experience a new or recurrent stroke each year,more than 500,000 survive(American Stroke Association,2007)[1]. Occupational therapy practitioners are critical rehabilitation professionals for stroke survivors.展开更多
As a novel chemical marker,methanol has been widely applied to evaluate the ageing state of insulating paper in recent years.Methanol gas sensor(MGS)could be applied to detect the methanol content in transformer oil f...As a novel chemical marker,methanol has been widely applied to evaluate the ageing state of insulating paper in recent years.Methanol gas sensor(MGS)could be applied to detect the methanol content in transformer oil for its high portability and stability.However,it has the defects of a high limit of detection(LOD)and poor anti-interference performance.Therefore,a novel method of detecting methanol in transformer oil based on MGS with the solid-phase extraction(SPE)technology was investigated in this paper.A detection platform for methanol in transformer oil based on SPE was established,and the SPE experimental process and the crucial parameters were optimised.The results show that the SPE decreased the LOD of MGS from 0.4 to 0.2 ppm and effectively eliminated the interfering substances in oil.Although a part of methanol would be lost during the SPE process,the regression correction coefficient was proposed to correct the evaluation errors.The results indicate that the average relative errors decreased from 17.09%to 4.38%,and the proposed method has good applicability.展开更多
文摘1 Introduction The proposal of the concept of“New Power System”aims to illustrate the transform direction of the traditional power system,acting as the development core of the future new power grid.To achieve this,the proposed strategic targets of“carbon neutralization and carbon peaking”must be implemented and insisted[1].The core feature of the new power system is that renewable energy plays a leading role and becomes the main source of energy supply,meanwhile,the goal of green energy utilization has also been put forward on the agenda.Green energy utilization includes two aspects,one is the exploitation and promotion of various green energy technologies,and the other is the digitalization of energy management.Under this trend,stochastic and fluctuating energy sources such as wind power and photovoltaic power replace deterministic controllable power sources such as thermal power,bringing challenges to power grid regulation and dispatching,as well as flexible operation.The large-scale integration of renewable energy and increasingly high proportion of power electronic equipment tend to bring about fundamental changes in the operation characteristics,safety control,and production mode of the power system.
基金supported by National Natural Science Foundation of China(Nos.51875199 and 51905165)Hunan Natural Science Fund Project(2019JJ50186)the Key Research and Development Program of Hunan Province(No.2018GK2073).
文摘To ensure wind turbine(WT)safe operations and improve the utilization rate of wind energy,effective evaluation of the operation state of the pitch system is critical.Therefore,a new method was proposed to evaluate the operation state of the pitch system of WT based on fuzzy comprehensive evaluation.Firstly,based on SCADA data,the working state of the pitch system under rated power state and power state of WT were analyzed.Secondly,through the analysis of characteristic parameters and physical mechanism of the pitch system,the consistency principle of characteristic parameters,the stability principle of power under rated state,and the stability principle of blade angle underpowered state were obtained.Next,based on the aforementioned principles,the evaluation indexes were established,and the fuzzy comprehensive evaluation method was used to establish the operation state evaluation model of the pitch system under rated power state and under power state of the WT.Finally,an example was provided to verify the effectiveness of the method.The evaluation model established in this study can be used as a technical reference for the online monitoring of WT pitch systems to ensure the safe and stable operation of WTs.
文摘Of the 700,000 people in the United States who experience a new or recurrent stroke each year,more than 500,000 survive(American Stroke Association,2007)[1]. Occupational therapy practitioners are critical rehabilitation professionals for stroke survivors.
基金supported by the State Grid Heilongjiang Electric Power Company Ltd.,Electric Power Research Institute Project(52243724000M)the China Postdoctoral Science Foundation(2020M670921)the National Natural Science Foundation of China(52307164).
文摘As a novel chemical marker,methanol has been widely applied to evaluate the ageing state of insulating paper in recent years.Methanol gas sensor(MGS)could be applied to detect the methanol content in transformer oil for its high portability and stability.However,it has the defects of a high limit of detection(LOD)and poor anti-interference performance.Therefore,a novel method of detecting methanol in transformer oil based on MGS with the solid-phase extraction(SPE)technology was investigated in this paper.A detection platform for methanol in transformer oil based on SPE was established,and the SPE experimental process and the crucial parameters were optimised.The results show that the SPE decreased the LOD of MGS from 0.4 to 0.2 ppm and effectively eliminated the interfering substances in oil.Although a part of methanol would be lost during the SPE process,the regression correction coefficient was proposed to correct the evaluation errors.The results indicate that the average relative errors decreased from 17.09%to 4.38%,and the proposed method has good applicability.
