To address the issues of limited demand response data,low generalization of demand response potential evaluation,and poor demand response effect,the article proposes a demand response potential feature extraction and ...To address the issues of limited demand response data,low generalization of demand response potential evaluation,and poor demand response effect,the article proposes a demand response potential feature extraction and prediction model based on data mining and a demand response potential assessment model for adjustable loads in demand response scenarios based on subjective and objective weight analysis.Firstly,based on the demand response process and demand response behavior,obtain demand response characteristics that characterize the process and behavior.Secondly,establish a feature extraction and prediction model based on data mining,including similar day clustering,time series decomposition,redundancy processing,and data prediction.The predicted values of each demand response feature on the response day are obtained.Thirdly,the predicted data of various characteristics on the response day are used as demand response potential evaluation indicators to represent different demand response scenarios and adjustable loads,and a demand response potential evaluation model based on subjective and objective weight allocation is established to calculate the demand response potential of different adjustable loads in different demand response scenarios.Finally,the effectiveness of the method proposed in the article is verified through examples,providing a reference for load aggregators to formulate demand response schemes.展开更多
With the increase of adjustable loads connected to power systems,there is a growing risk of intentionally exploiting load adjustability to cause power balance deviations.This poses an obvious threat to power system fr...With the increase of adjustable loads connected to power systems,there is a growing risk of intentionally exploiting load adjustability to cause power balance deviations.This poses an obvious threat to power system frequency,which has been noticed by many system operators.However,the current dispatch method cannot consider the attack of load on frequency,let alone providing a preventive dispatch decision that reduces the frequency deviation.To address this challenge,a preventive dispatch method that mitigates the impact of adjustable load on power system frequency is presented for the first time.The relationship between the time-varying power mismatch caused by the attack of adjustable load and frequency deviation is established.This is achieved by theoretically deriving the transfer function between system frequency and power mismatch in time domain and discretizing the function into several segments according to the division of time horizons.A formal analysis of the error caused by the transformation is performed,which provides quantitative guidance on the accuracy of the frequency modeling.Based on this,the worst-case scenario of frequency deviation with adjustable load is determined through solving an optimization model.Then,a novel preventive dispatch method that guarantees the system frequency security under the worst-case scenario is presented.Particularly,the generator ramping behavior after receiving the AGC adjustment command is modeled by a group of linear constraints to distinguish the load tracking abilities of generators.Case studies based on the IEEE30-bus system and a 661-bus utility system show that the proposed preventive dispatch method can achieve a 5.8%-19.42%improvement of the maximum absolute frequency deviation.展开更多
The China Fusion Engineering Test Reactor（CFETR） is under design, which aims to bridge the gaps between ITER and the future fusion power plant. The neutron wall loading（NWL） depends on the neutron source distribut...The China Fusion Engineering Test Reactor（CFETR） is under design, which aims to bridge the gaps between ITER and the future fusion power plant. The neutron wall loading（NWL） depends on the neutron source distribution, which depends on the density and temperature profiles. In this paper, we calculate the NWL of CFETR and study the effects of density and temperature profiles on the NWL distribution along the first wall. Our calculations show that for a 200 MW fusion power, the maximum NWL is at the outer midplane and the vaule is about 0.4 MW m^-2. The density and temperature profiles have little effect on the NWL distribution. The value of NWL is determined by the total fusion power.展开更多
A few post-bloom thinners are available for apple (Malus domestica Borkh.) and the prospects for additional thinners appear to be limited. Application of blossom thinners may present a risk of overthining in the areas...A few post-bloom thinners are available for apple (Malus domestica Borkh.) and the prospects for additional thinners appear to be limited. Application of blossom thinners may present a risk of overthining in the areas where weather is less predictable. Thus, we studied the impacts of various rates of 1-aminocyclopropane-1-carboxylic acid (ACC) in three strains of “Fuji” apple and different rates of ACC and one rate of Ethrel in “Buckeye Gala” apple, when fruitlet diameter was about 20 mm, on fruit set, yield and fruit quality attributes at harvest, and return bloom in southwest Idaho in the Intermountain West region, USA. In 2013, application of Ethrel at 300 mg·L<sup>-1</sup> did not affect fruit set, fruit weight, diameter (D), length(L), or L/D ratio 34 days after application, or yield, fruit weight, color, russet, and starch degradation pattern (SDP) at harvest, while application of ACC at 150 mg·L<sup>-1</sup> or higher reduced fruit set by 19% to 34% in “Buckeye Gala” apple. In this cultivar, application of ACC at 350 mg·L<sup>-1</sup> significantly increased fruit weight, diameter and length 34 days after application, and increased fruit weight, color, and SDP at harvest time. Application of ACC at all rates reduced total yield per tree in “Buckeye Gala”. Application of ACC at 300 mg·L<sup>-1</sup> significantly reduced fruit set but applications of 150 mg·L<sup>-1</sup> or 300 mg·L<sup>-1</sup> ACC did not affect yield or quality attributes of “Sun Fuji” apple in Sunny Slope area in 2013. Application of ACC reduced fruit set and slightly increased fruit size in “Top Export Fuji” in 2013. Application of ACC at 600 mg·L<sup>-1</sup> significantly reduced fruit set in “Aztec Fuji” apple in 2014. Application of ACC in a season never reduced bloom density (return bloom) of the next season. Overall, we conclude that ACC is an excellent tool as a late-season post-bloom fruit thinner and can be effective when applied fruitlet diameter is about 20 mm.展开更多
基金the National Natural Science Foundation of China Youth Fund,Research on Security Low Carbon Collaborative Situation Awareness of Comprehensive Energy System from the Perspective of Dynamic Security Domain(52307130).
文摘To address the issues of limited demand response data,low generalization of demand response potential evaluation,and poor demand response effect,the article proposes a demand response potential feature extraction and prediction model based on data mining and a demand response potential assessment model for adjustable loads in demand response scenarios based on subjective and objective weight analysis.Firstly,based on the demand response process and demand response behavior,obtain demand response characteristics that characterize the process and behavior.Secondly,establish a feature extraction and prediction model based on data mining,including similar day clustering,time series decomposition,redundancy processing,and data prediction.The predicted values of each demand response feature on the response day are obtained.Thirdly,the predicted data of various characteristics on the response day are used as demand response potential evaluation indicators to represent different demand response scenarios and adjustable loads,and a demand response potential evaluation model based on subjective and objective weight allocation is established to calculate the demand response potential of different adjustable loads in different demand response scenarios.Finally,the effectiveness of the method proposed in the article is verified through examples,providing a reference for load aggregators to formulate demand response schemes.
基金supported by the National Natural Science Foundation of China(No.52307082 and No.W2421081).
文摘With the increase of adjustable loads connected to power systems,there is a growing risk of intentionally exploiting load adjustability to cause power balance deviations.This poses an obvious threat to power system frequency,which has been noticed by many system operators.However,the current dispatch method cannot consider the attack of load on frequency,let alone providing a preventive dispatch decision that reduces the frequency deviation.To address this challenge,a preventive dispatch method that mitigates the impact of adjustable load on power system frequency is presented for the first time.The relationship between the time-varying power mismatch caused by the attack of adjustable load and frequency deviation is established.This is achieved by theoretically deriving the transfer function between system frequency and power mismatch in time domain and discretizing the function into several segments according to the division of time horizons.A formal analysis of the error caused by the transformation is performed,which provides quantitative guidance on the accuracy of the frequency modeling.Based on this,the worst-case scenario of frequency deviation with adjustable load is determined through solving an optimization model.Then,a novel preventive dispatch method that guarantees the system frequency security under the worst-case scenario is presented.Particularly,the generator ramping behavior after receiving the AGC adjustment command is modeled by a group of linear constraints to distinguish the load tracking abilities of generators.Case studies based on the IEEE30-bus system and a 661-bus utility system show that the proposed preventive dispatch method can achieve a 5.8%-19.42%improvement of the maximum absolute frequency deviation.
基金supported by the National Magnetic Confinement Fusion Program(Grant Nos.2014GB106001,2014GB110003 and 2013GB111000)by National Natural Science Foundation of China(Grant No.11675221)
文摘The China Fusion Engineering Test Reactor（CFETR） is under design, which aims to bridge the gaps between ITER and the future fusion power plant. The neutron wall loading（NWL） depends on the neutron source distribution, which depends on the density and temperature profiles. In this paper, we calculate the NWL of CFETR and study the effects of density and temperature profiles on the NWL distribution along the first wall. Our calculations show that for a 200 MW fusion power, the maximum NWL is at the outer midplane and the vaule is about 0.4 MW m^-2. The density and temperature profiles have little effect on the NWL distribution. The value of NWL is determined by the total fusion power.
文摘A few post-bloom thinners are available for apple (Malus domestica Borkh.) and the prospects for additional thinners appear to be limited. Application of blossom thinners may present a risk of overthining in the areas where weather is less predictable. Thus, we studied the impacts of various rates of 1-aminocyclopropane-1-carboxylic acid (ACC) in three strains of “Fuji” apple and different rates of ACC and one rate of Ethrel in “Buckeye Gala” apple, when fruitlet diameter was about 20 mm, on fruit set, yield and fruit quality attributes at harvest, and return bloom in southwest Idaho in the Intermountain West region, USA. In 2013, application of Ethrel at 300 mg·L<sup>-1</sup> did not affect fruit set, fruit weight, diameter (D), length(L), or L/D ratio 34 days after application, or yield, fruit weight, color, russet, and starch degradation pattern (SDP) at harvest, while application of ACC at 150 mg·L<sup>-1</sup> or higher reduced fruit set by 19% to 34% in “Buckeye Gala” apple. In this cultivar, application of ACC at 350 mg·L<sup>-1</sup> significantly increased fruit weight, diameter and length 34 days after application, and increased fruit weight, color, and SDP at harvest time. Application of ACC at all rates reduced total yield per tree in “Buckeye Gala”. Application of ACC at 300 mg·L<sup>-1</sup> significantly reduced fruit set but applications of 150 mg·L<sup>-1</sup> or 300 mg·L<sup>-1</sup> ACC did not affect yield or quality attributes of “Sun Fuji” apple in Sunny Slope area in 2013. Application of ACC reduced fruit set and slightly increased fruit size in “Top Export Fuji” in 2013. Application of ACC at 600 mg·L<sup>-1</sup> significantly reduced fruit set in “Aztec Fuji” apple in 2014. Application of ACC in a season never reduced bloom density (return bloom) of the next season. Overall, we conclude that ACC is an excellent tool as a late-season post-bloom fruit thinner and can be effective when applied fruitlet diameter is about 20 mm.
