查看更多>>摘要：A reliable and robust communication network is es-sential to exchange information between distributed generators(DGs)and accurately calculate their control actions in mi-crogrids(MGs).However,the integration of the communication network and MGs poses challenges related to the flexibility,availability,and reliability of the system.Furthermore,random communication disorders such as time delays and packet loss can negatively impact the system performance.Therefore,it is essential to design a suitable secondary controller(SC)with a fast dynamic response to restore voltage and appropriate power-sharing,while ensuring that the effects of random communica-tion disorders are eliminated.In this regard,an optimal distrib-uted hybrid model predictive secondary control method is pre-sented in this paper.Realistic simulations are carried out in a mixed simulation environment based on MATLAB and OM-NET++,by considering IEEE 802.11(WiFi)using the recently developed Internet networking(INET)framework.In the imple-mented application layer,the recoveryUnit is responsible for re-ducing the impact of random communication disorders.The ef-fectiveness and performance of the proposed method in compar-ison with a conventional model predictive control are verified by simulation results.
查看更多>>摘要：This paper proposes an online framework to char-acterize demand response(DR)over time.The proposed frame-work facilitates obtaining and updating the daily consumption patterns of customers.The essential concept of response profile class(RPC)is introduced for characterization and complement-ed by the measure of the variability in customer behavior.This paper uses a modified version of the incremental clustering by fast search and find of density peaks(CFSFDP)algorithm for daily profiles,considering the multivariate normal kernel densi-ty estimator and incremental forms of the Davies-Bouldin(iDB)and Xie-Beni(iXB)validity indices.Case studies conducted using real-world and simulated daily profiles of residential and com-mercial Chilean end-users have demonstrated how the proposed framework can continuously characterize DR.The proposed framework is proven to achieve realistic customer models for ef-fective energy management by estimating the customer response to price signals at the distribution system operator(DSO)level.
查看更多>>摘要：Non-intrusive load monitoring is a technique for monitoring the operating conditions of electrical appliances by collecting the aggregated electrical information at the household power inlet.Despite several studies on the mining of unique load characteristics,few studies have extensively considered the high computational burden and sample training.Based on low-frequency sampling data,a non-intrusive load monitoring algo-rithm utilizing the graph total variation(GTV)is proposed in this study.The algorithm can effectively depict the load state without the need for prior training.First,the combined K-means clustering algorithm and graph signals are used to build concise and accurate graph structures as load models.The GTV representing the internal structure of the graph signal is introduced as the optimization model and solved using the aug-mented Lagrangian iterative algorithm.The introduction of the difference operator reduces the computing cost and addresses the inaccurate reconstruction of the graph signal.With low-fre-quency sampling data,the algorithm only requires a little prior data and no training,thereby reducing the computing cost.Ex-periments conducted using the reference energy disaggregation dataset and almanac of minutely power dataset demonstrated the stable superiority of the algorithm and its low computation-al burden.
查看更多>>摘要：Hybrid multi-terminal direct current(MTDC)transmission technology has been a research focus,and primary frequency regulation(FR)improvement in the receiving-end sys-tem is one of the problems to be solved.This paper presents a decentralized primary FR scheme for hybrid MTDC power sys-tems considering multi-source enhancement to help suppress frequency disturbance in the receiving-end systems.All the con-verters only need local frequency or DC voltage signal input to respond to system disturbance without communication or a con-trol center,i.e.,a decentralized control scheme.The proposed scheme can activate appropriate power sources to assist in FR in various system disturbance severities with fine-designed thresholds,ensuring sufficient utilization of each power source.To better balance FR performance and FR resource participa-tion,an evaluation index is proposed and the parameter optimi-zation problem is further conducted.Finally,the validity of the proposed scheme is verified by simulations in MATLAB/Simu-link.
查看更多>>摘要：The hybrid cascaded high-voltage direct current(HVDC)transmission system has various operation modes,and some operation modes have sharply increasing requirements for protection rapidity,while the traditional pilot differential pro-tection(PDP)has poor rapidity,and even refuses to operate when faults occur on the DC line.Therefore,a novel pilot pro-tection scheme based on traveling wave characteristics is pro-posed.First,the adaptability of the traditional PDP applied in engineering is analyzed for different operation modes.Then,the expressions of the forward traveling wave(FTW)and back-ward traveling wave(BTW)on the rectifier side and the invert-er side are derived for different fault locations.From the theo-retical derivation,the difference between the BTW and FTW on the rectifier side is less than zero,and the same is true on the inverter side.However,in the event of an external fault of DC line,the difference between the BTW and FTW at near-fault terminal protection installation point is greater than zero.Therefore,by summing over the product of the difference be-tween BTW and FTW of the rectifier side and that of the in-verter side,the fault identification criterion is constructed.The simulation results show that the proposed pilot protection scheme can quickly and reliably identify the short-circuit faults of DC line in different operation modes.
查看更多>>摘要：Two-level totem-pole power factor correction(PFC)converters in critical conduction mode(CRM)suffer from the wide regulation range of switching frequency.Besides,in high-frequency applications,the number of switching times increas-es,resulting in significant switching losses.To solve these issues,this paper proposes an improved modulation strategy for the single-phase three-level neutral-point-clamped(NPC)converter in CRM with PFC.By optimizing the discharging strategy and switching state sequence,the switching frequency and its varia-tion range have been efficiently reduced.The detailed perfor-mance analysis is also presented regarding the switching fre-quency,the average switching times,and the effect of voltage gain.A 2 kW prototype is built to verify the effectiveness of the proposed modulation strategy and analysis results.Compared with the totem-pole PFC converter,the switching frequency reg-ulation range of the three-level PFC converter is reduced by 36.48％and the average switching times is reduced by 45.10％.The experimental result also shows a 1.2％higher efficiency for the three-level PFC converter in the full load range.
查看更多>>摘要：Aiming at multi-agent coordinated scheduling prob-lems in power systems under uncertainty,a generic projection and decomposition(P&D)approach is proposed in this letter.The canonical min-max-min two-stage robust optimization(TSRO)model with coupling constraints is equivalent to a con-cise robust optimization(RO)model in the version of mixed-in-teger linear programming(MILP)via feasible region projec-tion.The decentralized decoupling of the non-convex MILP problem is realized through a dual decomposition algorithm,which ensures the fast convergence to a high-quality solution in the distributed optimization.Numerical tests verify the superior performance of the proposed P&D approach over the existing distributed TSRO method.
查看更多>>摘要：This letter studies large-disturbance stability of the power system with a synchronous generator(SG)and a convert-er-interfaced generation(CIG)connected to infinite bus.The power system is multi-timescale and first simplified.It is shown that the boundary of region of attraction(ROA)of the simpli-fied model is composed of stable manifolds of unstable equilibri-um point(UEP)or semi-singular point(SSP),named anchor points,and singular surface pieces.The type of anchor point de-termines the dominant instability pattern of the power system.When the anchor point is UEP or SSP,the dominant instability pattern is the instability of rotor angle of SG or the instability of phase-locked loop and outer control loop(OCL)of CIG,re-spectively.Transition of dominant instability pattern can be ana-lyzed with the relative position relationship between UEP and SSP.The effect of OCL is discussed.When the OCL is activat-ed,the ROA becomes smaller and the system is more prone to instability of CIG.It is necessary to consider the OCL when studying the large-disturbance stability of the power system.
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