查看更多>>摘要：In recent years,the expansion of the power grid has led to a continuous increase in the number of consumers within the distribution network.However,due to the scarcity of historical data for these new consumers,it has become a com-plex challenge to accurately forecast their electricity demands through traditional forecasting methods.This paper proposes an innovative short-term residential load forecasting method that harnesses advanced clustering,deep learning,and transfer learning technologies to address this issue.To begin,this paper leverages the domain adversarial transfer network.It employs limited data as target domain data and more abundant data as source domain data,thus enabling the utilization of source do-main insights for the forecasting task of the target domain.Moreover,a K-shape clustering method is proposed,which effec-tively identifies source domain data that align optimally with the target domain,and enhances the forecasting accuracy.Sub-sequently,a composite architecture is devised,amalgamating at-tention mechanism,long short-term memory network,and seq2seq network.This composite structure is integrated into the domain adversarial transfer network,bolstering the perfor-mance of feature extractor and refining the forecasting capabili-ties.An illustrative analysis is conducted using the residential load dataset of the Independent System Operator to validate the proposed method empirically.In the case study,the relative mean square error of the proposed method is within 30 MW,and the mean absolute percentage error is within 2%.A signifi-cant improvement in accuracy,compared with other compara-tive experimental results,underscores the reliability of the pro-posed method.The findings unequivocally demonstrate that the proposed method advocated in this paper yields superior fore-casting results compared with prevailing mainstream forecast-ing methods.
查看更多>>摘要：Electrical water heaters(EWHs)are important can-didates to provide demand-response services.The traditional op-timization method for EWHs focuses on the optimization of the electricity consumption,without considering the shifting poten-tial of the water-use activities.This paper proposes an optimiza-tion method for EWHs considering the shifting potentials of both the electricity consumption and water-use activities.Con-sidering that the water-use activities could be monolithically shifted,the shifting model of the water-use activities was devel-oped.In addition to the thermodynamic model of the EWH,the optimal scheduling model of the EWH was developed and solved using mixed-integer linear programming.Case studies were performed on a single EWH and aggregate EWHs,demon-strating that the proposed method can shift the water-use activi-ties and therefore increase the load-shifting potential of the EWHs.
查看更多>>摘要：Demand response transactions between electric con-sumers,load aggregators,and the distribution network manag-er based on the"combination of price and incentive"are feasi-ble and efficient.However,the incentive payment of demand re-sponse is quantified based on private information,which gives the electric consumers and load aggregators the possibility of defrauding illegitimate interests by declaring false information.This paper proposes a method based on Vickrey-Clark-Groves(VCG)theory to prevent electric consumers and load aggrega-tors from taking illegitimate interests through deceptive behav-iors in the demand response transactions.Firstly,a demand re-sponse transaction framework with the price-and-incentive com-bined mode is established to illustrate the deceptive behaviors in the demand response transactions.Then,the idea for eradi-cating deceptive behaviors based on VCG theory is given,and a detailed VCG-based mathematical model is constructed follow-ing the demand response transaction framework.Further,the proofs of incentive compatibility,individual rationality,cost minimization,and budget balance of the proposed VCG-based method are given.Finally,a modified IEEE 33-node system and a modified IEEE 123-node system are used to illustrate and val-idate the proposed method.
查看更多>>摘要：The accurate identification of smart meter(SM)fault types is crucial for enhancing the efficiency of operation and maintenance(O&M)and the reliability of power collection systems.However,the intelligent classification of SM fault types faces significant challenges owing to the complexity of features and the imbalance between fault categories.To address these is-sues,this study presents a fault diagnosis method for SM incor-porating three distinct modules.The first module employs a combination of standardization,data imputation,and feature extraction to enhance the data quality,thereby facilitating im-proved training and learning by the classifiers.To enhance the classification performance,the data imputation method consid-ers feature correlation measurement and sequential imputation,and the feature extractor utilizes the discriminative enhanced sparse autoencoder.To tackle the interclass imbalance of data with discrete and continuous features,the second module intro-duces an assisted classifier generative adversarial network,which includes a discrete feature generation module.Finally,a novel Stacking ensemble classifier for SM fault diagnosis is de-veloped.In contrast to previous studies,we construct a two-lay-er heuristic optimization framework to address the synchronous dynamic optimization problem of the combinations and hyper-parameters of the Stacking ensemble classifier,enabling better handling of complex classification tasks using SM data.The pro-posed fault diagnosis method for SM via two-layer stacking en-semble optimization and data augmentation is trained and vali-dated using SM fault data collected from 2010 to 2018 in Zheji-ang Province,China.Experimental results demonstrate the ef-fectiveness of the proposed method in improving the accuracy of SM fault diagnosis,particularly for minority classes.
查看更多>>摘要：The oscillation phenomena associated with the con-trol of voltage source converters(VSCs)are concerning,mak-ing it crucial to locate the sources of such oscillations and sup-press the oscillations.Therefore,this paper presents a location scheme based on the energy structure and nonlinearity detec-tion.The energy structure,which conforms to the principle of the energy-based method and dissipativity theory,is developed to describe the transient energy flow for VSCs,based on which a defined characteristic quantity is implemented to narrow the scope for locating the sources of oscillations.Moreover,based on the self-sustained oscillation characteristics of VSCs,an in-dex for nonlinearity detection is applied to locate the VSCs that produce the oscillation energy.The combination of the energy structure and nonlinearity detection distinguishes the contribu-tions of different VSCs to the oscillation.The results of a case study implemented by the PSCAD/EMTDC simulation validate the proposed scheme.
查看更多>>摘要：Previous studies have demonstrated that disharmo-ny among voltage-source-controlled units(VSCUs)may occur on an alternating current(AC)transmission or distribution line under steady-state operating conditions(SSOCs)or quasi-static operating conditions(QSSOCs).As the studies on frequency dis-harmony have been expanded to multiple disharmonized VS-CUs in the local power grid,its adverse effects on AC lines and equivalent load(EL)at the bus without active voltage control ability(non-active bus)need to be investigated further.Consid-ering the locality of disharmony and common topological con-nections among VSCUs,this paper adopts a Y-type three-termi-nal local power grid(LPG)as the research object.The dishar-mony among the three VSCUs is discussed.Firstly,for the load at non-active bus,the formulas for single-phase instantaneous voltage,load current,load power,as well as average power un-der disharmony operating conditions(DOCs)are derived.The characteristic indicators of the above electrical quantities are defined,which can measure the amplification and reduction de-grees of the above electrical quantities before and after dishar-mony.Secondly,for the line directly connected to VSCUs,the formulas for single-phase instantaneous line current and power and the average power under DOCs are derived.The character-istic indicators of power flow are defined,which can be used to quantify the peak amplification impact of oscillation before and after disharmony.Finally,the case study on the Y-type three-terminal LPG under the single-disharmony and the multi-dis-harmony switching scenarios indicates that the long-period pow-er oscillation caused by disharmony may occur in the load flow at the non-active bus and the line flow.The oscillation causes a serious decrease in load capability and a significant amplifica-tion of the peak of line power oscillation.
查看更多>>摘要：In line commutated converter based high-voltage direct current(LCC-HVDC)transmission systems,the trans-former saturation can induce harmonic instability,which poses a serious threat to the safe operation of the power system.How-ever,the nonlinear characteristics of the power grids introduced by the transformer saturation considerably limit the application of the conventional analysis methods.To address the issue,this paper derives a linear model for the transformer saturation caused by the DC current due to the converter modulation.Af-terwards,the nonlinear characteristics of power grids with the transformer saturation is described by a complex valued imped-ance matrix.Based on the derived impedance matrix,the sys-tem harmonic stability is analyzed and the mechanism of the transformer saturation induced harmonic instability is revealed.Finally,the sensitivity analysis is conducted to find the key fac-tors that influence the system core saturation instability.The proposed impedance model is verified by the electromagnetic transient simulation,and the simulation results corroborate the effectiveness of the proposed impedance model.
查看更多>>摘要：Dynamic operating envelopes(DOEs),as key en-ablers to facilitate distributed energy resource(DER)integra-tion,have attracted increasing attention in the past years.How-ever,uncertainties,which may come from load forecasting er-rors or inaccurate network parameters,have been rarely dis-cussed in DOE calculation,leading to compromised quality of the hosting capacity allocation strategy.This letter studies how to calculate DOEs that are immune to such uncertainties based on a linearised unbalanced three-phase optimal power flow(UTOPF)model.With uncertain parameters constrained by norm balls,formulations for calculating robust DOEs(RDOEs)are presented along with discussions on their tractability.Two cases,including a 2-bus illustrative network and a representa-tive Australian network,are tested to demonstrate the effective-ness and efficiency of the proposed approach.
查看更多>>摘要：This study presents a harmonic transfer function(HTF)based single-input single-output(SISO)impedance mod-eling method.The method converts an HTF from phase domain to sequence domain and then transforms it into an SISO imped-ance while preserving the frequency coupling information of dif-ferent sequences and different harmonics.Applications of this method to a line-commutated converter based high-voltage di-rect current(LCC-HVDC)system are presented.The results demonstrate the accuracy of the derived SISO impedance,and a truncation-order selection is suggested.The case study shows that the proposed method facilitates simpler impedance mea-surements and associated stability analysis.
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