| Energy Losses in distribution network is an important index for measure the level of economic operation.With more and more serious of power quality problems in the low voltage distribution network,additional losses of distribution network caused by power quality problems is increasing quickly.Energy losses produced by low voltage distribution network account for more than half of the total distribution network losses of our country,while power quality problem have a great influence on the losses of low voltage distribution network and cannot be ignored.Electronic power of low voltage distribution network mostly used by residents,Residents' power consumption of our country takes about 12% of the total power consumption at present which takes about 36% in the United States,so it reflects that our residential power consumption also has a great development and saving space.It will have an extremely vital significance to electric power industry for achieving energy conservation and power losses reduction to calculatethe loss of low voltage power distribution network accurately and analyze out the loss caused by various problems.Firstly,three most commonly power quality problems(three-phase imbalance,harmonic and voltage deviation)in the low voltage distribution network are analyzed in detail in this paperbefore loss calculation of distribution network.Thenin order to study the effect of power quality problem on the losses of low voltage power distribution network,the paper adopts the method of equivalent resistance to simplify the low voltage distribution network,then respectively analysis of the loss characteristics of the transformer and line under the influence of three kinds of power quality problems.At the same time,phase angle unbalance,dynamic unbalance and harmonic unbalance concepts are brought in during the process of analysis,and corresponding calculation method is also given.Then in order to make the assessment of low voltage distribution network losses more accurate,traditional method of equivalent resistance is improved first of all and the equivalent resistance method considering voltage deviation and harmonic is proposed.Simple simulation model of 0.4kV low voltage distribution network is built by the ETAP power analysis software in this paper,loss impact on low voltage power distribution network of the three kinds of power quality problems are analyzed respectively.Then method of choosing representative day are introducedin thispaper,then Q cluster based on method considering the special load dayare analyzed.Finally,loss calculation method of low voltage power distribution network is put forward to considering three-phase imbalance,harmonic and voltage deviation on the basis of analysis of three kinds of power quality problems impact on low voltage power distribution network losses,the calculation accuracy of the model in the low voltage distribution network losses is verified by examples.In additionally,loss size of the distribution network caused by each power quality problems is analyzed in paper which has a guiding significance to the management of power quality problem. |
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