Research On Power Flow Calculation Method Of Distributed Generation In Distribution Network

At present,China's power industry is developing global energy Internet and smart grid to achieve energy strategic transformation.The addition of distributed power supply has injected new vitality into traditional power generation methods.It not only conforms to the current concept of green development,is in line with the new trend of low-carbon economy,but also enables flexible and diverse power generation methods,provides a quality of life for the people.The development brings huge benefits.However,the addition of distributed power sources has changed the structure and operating mode of distribution networks,making it more complex to study the distribution network with distributed power supply.Because of the particularity of the circuit structure of the distribution network,this paper studies the three-phase power flow calculation of a weak-loop distribution network with distributed power supply.The main contents of the paper are as follows:First of all,for the structural characteristics of three-phase unbalanced distribution network and large R/X line parameters,a three-phase model of the relevant components of the distribution network was established.It lays the foundation for the three-phase power flow calculation of the weak-loop distribution network.Secondly,several methods for solving power flow calculations in distribution networks are introduced,and the previous generation method is taken as the core,and the algorithm is improved.A more concise algorithm is used to calculate the radial network.The algorithm is based on the road matrix,establishes the relationship matrix of node injection current and node voltage,so as to quickly find out the trend of the distribution network,which greatly saves the calculation time and memory footprint.In addition,shorttime ring networks appear during the fault processing and network reconstruction of distribution networks.This paper uses the superposition theorem to unwind the weak-loop distribution network,so that the distribution network is decomposed into two parts.One part is a pure radial network,which is solved by the direct method based on the road matrix,and the other part is a pure ring network.It is solved by the loop current method.Then the superposition of these two networks can be used to derive the trend of the weak-loop distribution network.Then,for each type of distributed power supply control method and grid connection method,a variety of distributed power flow calculation models are elaborated in detail.Compared with the traditional distribution network power flow calculation,new node types emerge,namely PQ node,PI node,PQ(V)node,and PV node.Finally,the treatment methods of each node in the three-phase power flow calculation of distribution network are discussed.When solving distribution networks containing distributed power of PV type nodes,the reactive power principle is used to solve the initial reactive power value,and then the PV node is transformed into a PQ node by solving its reactive power compensation amount.Other nodes are similarly transformed into PQ nodes that can be processed.Thus,the different DGs are processed into different types of nodes and brought into distribution network power flow calculation to solve the weak-ring distribution network problem with distributed power supply.