Distribution Network State Estimation with Multi-scan Measurements Considering Tap Ratio Error of Distribution Transformers
The weakness of measurement configuration is always an important reason plaguing the accuracy of distribution network state estimation(DSE).The widespread application of intelligent fusion terminals enriches measurement configuration of the distribution network,which extends the range of DSE to the lower side of distribution transformers(DTs)and puts forward higher requirements for the accuracy of DT parameters.The large quantity of DTs results in significant maintenance workload and the current difficulty in ensuring parameter accuracy,with tap ratio errors being a key factor leading to low accuracy of DSE.According to the characteristics of the widespread use of no-load tap changers and the low frequency of tap ratio variations in DTs,this paper proposes a DSE method with multi-scan measurements considering tap ratio errors of DTs.By establishing a distribution network state estimation with multi-scan measurement model based on quadratic forms in a rectangular coordinate system and solving it using orthogonal transformation methods,the accurate estimation of tap ratios of DTs can be achieved.The DSE results of the modified IEEE 33 system and an actual distribution network show that the proposed method can give accurate estimation of transformer tap ratios,which helps to detect and correct the tap ratio errors in time,reduces the parameter maintenance workload and improves the accuracy of DSE.
distribution networkdistribution transformertap ratiostate estimationmulti-scan measurementquadratic estimation problem of quadratic constraint
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