Calculation Method Research About Ultimate Line Losses Of10kV Distribution Network

Line loss of distribution network is an important indicator of the electrical powersystem’s economical operation, which reflects the level of planning, design andoperational management of a power grid. Concerning that the load shape coefficient ofdistribution network is difficult to accurately acquired, the theoretical line losscalculating result through the typical day can’t be directly applicable to deliver theassessment indicators. According to the definition and the physical meaning of the loadshape coefficient in the average current method, this literature calculated the limitation of10kV distribution network’s variable loss, in which each transformer and branch wascalculated. This literature took the enterprise dedicated line’s power supply into account,and ultimately got the range of10kV distribution network’s theoretical line loss rate.In the process of calculating the variable loss limit of the common powerdistribution transformers, this paper deduced the transformer’s limited monthly loadcurve in theory. The maximum loss monthly load curve was the "square wave" formed bythe monthly maximum and minimum load under the constraint of the transformerpower supply, and the minimum loss monthly load curve is fitted through averagemonthly load of the transformers, in which monthly maximum and minimum loadappeared by the "shock pulse" form.When calculating each branch line’s limit loss of the feeder lines, this literaturefitted each branch’s limited load curve from backward to the forward according to grid’stopology that based on the idea of the monthly load curve shape coefficient. Then iteventually obtained the limit line loss of each branch through average current method. Inaddition, considering the maximum load constraint at the outlet of the feeder lines, theliterature put forward to a practical iterative method to solve the maximum line loss.This method used a time parting way acquired limited load curves’ best combination ofeach transformer in each time frame, in which the power loss of public feeder lines tookthe maximum value. Then this literature got the monthly maximum and minimum load’stime distribution of the transformer limit load curve in the calculating month, and then induced all monthly limit load curves of branch lines from backward to forward. Finallyit got monthly loss maximum values of each branch lines under the constraint at feederoutlet.Eventually, this literature took a certain power supply bureau’s10kV distributiongrid as an example to illustrate ideas this paper putting forward, and verify itseffectiveness and feasibility.In view of the complexity of the distribution network topology, the lowmeasurement automation level, the mass data, varieties of problems exists in thedistribution network line loss’s management of the power supply companies. Becausethis paper analyzed10kV distribution networks’ each transformers and branch lines,result of the paper can help serious check those lines which existing abnormal line loss,dig the weaknesses in line loss’s management and excavate spaces in redacting line losstechnical line loss. In addition, the calculation results of the paper can be applied as animportant accordance for Superior departments to learn the actual truth of the regionaldistribution network. It also can help issue assessment indicators and evaluateenterprise’s line loss’s management level of the distribution network. Thereby, all ofthose can urge the subordinate departments to improve the quality of line loss’smanagement.