Research On Three-Phase Unbalanced Power Flow Calculation Method For Complex Distribution Network

At present,the problems in the calculation of three-phase unbalanced power flow in complex distribution network are as follows:?The existing three phase unbalanced steady state model of distributed generator(DG)with doubly fed induction generator(DFIG)does not fully consider the control characteristics of three phase unbalance,and the model is not perfect.?For a large number of induction motors in the distribution network,its three-phase steady state model doesn't consider the saturation characteristic when in unbalance.?For power flow calculation of the three-phase unbalanced distribution network,it cost a lot of computing resource when used phase component calculate method.But it became complicated when the phase and sequence mixed calculate method have been used.The work of this article is as follows:(1)The equation of active power and reactive power of input and output ports of three-phase unbalanced lines and transformers is derived.(2)Three phase unbalanced steady state modeling of distributed generator is carried out by sequence component method:1)Grid connected synchronous generator which include small hydroelectric generating equipment and cogeneration unit.2)Grid connected inverter which include battery,fuel cell and photovoltaic power generation equipment.3)Doubly fed induction generator.And the main contribution is that the three-phase unbalanced steady state model of doubly fed induction generator which considered the different control strategy when grid unbalanced.The electromagnetic transient simulation of the average value model of the doubly fed induction generator in Simulink is used to verify the validity and correctness of the proposed steady state model.(3)As the three-phase unbalanced steady-state model of the current induction motor has not considered saturation characteristic.This paper presents a three-phase unbalanced steady state model of induction motor with saturation characteristic.And then proves the correctness of the proposed model and method.And the electromagnetic transient model of Simulink saturated induction motor is used to verify the correctness of the proposed model and method.(4)Finally,the three phase unbalanced power flow of complex distribution network is calculated based on MATE algorithm,and the problem that phase and sequence mixed calculation method complicated is solved.