Reaserch On Negative Sequence Voltage Responsibility Of Unbalanced Sources

In view of the three-phase unbalance problem in the power grid,a series of norms and standards have been developed by relevant institutions at home and abroad,which stipulate the safe threshold value of the voltage unbalance and current unbalance degree.However,it is not possible to effectively manage the users who are not exceeding the standard and continue to generate negative sequence voltage and current in the power grid.The quantitative division of the responsibility that the unbalanced source users should bear in the focus area and the corresponding management mode can help the governance of the three-phase unbalance problem.Since the main responsibility of the power grid is to supply customers with high quality voltage through the bus line,this paper chooses negative sequence voltage to study the problem of allocating unbalanced source responsibility.Firstly,this paper studied the responsibility allocation problem of negative sequence voltage sources in the same bus with the circuit parameter symmetry and determined the negative sequence voltage responsibility definition of single unbalanced source and multiple unbalanced sources,and that equivalent negative sequence model and the linear regression model of complex domain were established,in which subdivision iterations is introduced into the return of the model parameters.Secondly,the equivalent negative sequence model of the asymmetric transmission line parameters was established by strict formulas being deduced and the calculation method of the parameters in the model was determined.negative sequence voltage responsibility of the equivalent source voltage source,transmission line,the unbalance loads in simulation example was calculated and the results verify the accuracy and feasibility of the proposed method.Lastly,the equivalent negative sequence model and linear regression model of unbalanced system in which unbalanced sources were at different buses were set up.The introduction of transfer impedance can effectively solve individual negative sequence voltage which is produced at focus bus of all the unbalanced sources,and negative sequence voltage responsibility of the unbalanced source was calculated,which provides theory reference for three-phase unbalanced responsibility of distribution network.