Research On Residential Load Characteristic And Its Application

With the improvement of people’s living standards，the number and types ofhousehold appliances use are growing, led to the current characteristic of residentialelectricity load has been greatly changed. Usually there are errors on the residential loadestimation.While these electrical equipments are mostly single-phase nonlinear loadswhich results in the low voltage system harmonic content is relatively large. So need tocarry out a comprehensive systematic research.In the paper, based on measured data the electricity characteristics of residentialload and the daily load curves of different distribution lines are analyzed. Aiming at theproblem of the characteristic parameters of the load curve and the load rate oftransformer is low, the research on estimation method for the residential load is putforward. Through the analysis of the experimental data of a large number ofsingle-family loads, get the power distribution in every half hour. Kernel densityestimation method is used for each time period of data fitting. Proposed the method ofestablishment the daily load curve by random sampling and determine the demandfactor. This method can effectively use the automatic meter reading system data, updatethe basic parameters required for the load calculation—demand factor. To avoid theproblems of large deviation between load calculation results and the actual use results.The extensive use of single-phase nonlinear properties electrical equipment,resulting in low voltage power distribution system contains a lot of higher harmoniccurrent, especially the3rd harmonic current. Harmonic problem has been a problem thatcan not be ignored in the distribution system. In order to know the specific harmonics indistribution system of residential load, in this paper harmonic current is analyzed ondifferent distribution circuit of a residential area. According to the experimental data,current harmonic characteristics were compared and analyzed within one day and oneyear respectively. In addition to the current harmonic characteristics of a certain officeinto line are analyzed. This paper lays a theoretical foundation for harmonic loadprediction and elimination in low voltage distribution system.In low-voltage distribution system3rd harmonic current content is big enough. It isa common characteristic. Through analyzing the characteristics of harmonic, a newopen-neutral fault detection approach is proposed in the paper that monitoring devicecan be simply installed at feeder head. Main idea of the proposed approach is that the fault can be identified according to the3rd harmonic variation measured at the feederhead. Simulation and experimental analysis shows that: the3rd harmonic current willshow varying degrees of change at the feeder head when open neutral fault occurs,regardless of the load is balanced or unbalanced. The fault location is closer to feederhead indicates that the3rd harmonic current change is more significant. In the paperresearches and analyzes the3rd harmonic and fundamental currents sudden changemethod at feeder head when open-neutral fault happened, as well as3rd harmonic andfundamental currents of load fluctuation method during normal operation. Obtainedfault criterion and fault identification processes that can effectively distinguish betweenopen-neutral fault and normal operation. Based on the experimentally measured loadfluctuation data for simulation study, verified the fault detection criterion is validity toopen-neutral fault whenever in balanced and unbalanced load conditions.