Research On A State Estimation Of Medium And Low Voltage Distribution Network With Distributed Generation

Different from the power system transmission network,the automation level of distribution network is lower and the measurement amount can be collected is less,on the basis of considering the distribution structure and the three-phase imbalance characteristics,how to make full use of the limited amount of measurement to estimate the state of the whole distribution network,become a problem to be solved at this stage,Therefore,it is of great theoretical significance to study the state estimation methods that can be used to deal with three-phase three wire and three-phase four wire measurement simultaneously.With the expansion of the medium and low voltage distribution network,the increasing complexity of the structure,three-phase distribution network asymmetry and a large number of distributed power access,distributed state estimation can be processed by dimension reduction,So as to effectively decompose the large-dimensional power system state estimation problem into a series of smaller dimensionality estimation problems to solving,and to achieve the state estimation of the parallel computing.Therefore,how to use the method of distributed state estimation to realize the state estimation of medium and low voltage distribution network becomes an urgent problem that needs to be solved urgently.This article mainly aims at the above mentioned issues,a detailed study on the state estimation of medium and low voltage distribution network with distributed generations,specific research contents are as follows:Firstly,the correlative model of state estimation in medium and low voltage distribution network is established,including three-phase double winding transformer model,equivalent circuit model and distributed generations model for medium and low voltage distribution network,considering the influence of transformer in the process of dealing with the equivalent circuit of the medium and low voltage distribution network,and then on the basis to derive the establishment of its endpoint injection current equation,the model can be used to solve the state estimation problem of the medium and low voltage distribution network system,which includes three-phase three wire system andthree-phase four wire system.Secondly,a state estimation method for medium and low voltage distribution network based on bacterial colony chemotaxis algorithm is proposed.According to the equation of node injection current,the method can be used to measure the three-phase three wire and three-phase four wire system,a mathematical model for the state estimation of medium and low voltage distribution networks with distributed generation is established by using the weighted least squares method,the model also considers the strict zero injection equality constraints and inequality constraints;at last,the bacterial colony chemotaxis algorithm is used to solve the problem.Finally,an extended partition scheme is proposed to deal with the state estimation of medium and low voltage distribution network,and a multi-agent system framework based on blackboard model is established,At the same time,an effective boundary coordination strategy is developed,a multi-agent distributed state estimation method based on blackboard model is proposed to solve the problem of state estimation of medium and low voltage distribution network with distributed generations.