Node Admittance Matrix And Non Expansive Power Flow Algorithm For Asymmetric Networks

With the development of modern power grid,especially,the smart grid is proposed,the importance of the distribution network is becoming more and more prominent.In terms of power generation and transmission,the distribution network is the key link to ensure the reliability and security of power supply,and it is also the core of the smart grid.Owing to Application of power electronic components in distribution network,component parameter asymmetry,Three phase load asymmetry caused by diversity of power load,distributed power access and the asymmetry caused by the change of operating conditions ect,These factors make the imbalance of distribution network more and more prominent.Compared with the symmetrical three-phase system,the key problem to be solved in three-phase unbalanced distribution network analysis is three phase load asymmetry,Three phase line parameter asymmetry problem and Power flow iterative algorithm for PQ load in distribution network.In this paper,the circuit of three-phase mutual inductance coupling and asymmetric parameters is equivalent to three phase grid circuit,which makes the analysis and calculation of three-phase asymmetric network is capable of continuing the more mature node voltage method of symmetrical circuit analysis.The phase component model can reflect the physical characteristics of the actual operation of the system,which makes a concise,intuitive and accurate description of the operation status of distribution network,and the calculation and analysis of distribution network does not require the strict conditions such as the symmetrical component method.Secondly,in view of the specific characteristics of the heavy PQ load and the lack of voltage support of the PV node in the distribution network,a new fixed point non expansion iterative algorithm is proposed.This algorithm can be used to solve the problem of fast iterative of high precision power flow in the radiation comb distribution network with Multi PQ load node by the method of node load equivalent admittance successive approximation.Simulation results on IEEE33-bus and IEEE 123-bus distribution system show that the proposed algorithm is Practical and effective in Power flow calculation of distribution network.With the aggravation of energy crisis and environmental problems,more and more attention has been paid to the new energy sources,and the corresponding distributed generation technology has become the development trend of the future distribution network.With the development of social economy,the defects of the traditional centralized power supply mode are more and more outstanding,which can not meet the demand of current power supply.The access of distributed power injects vitality into the traditional distribution network,but also brings new challenges to the distribution network.The access of distributed power system changes the original structure and operation mode of distribution network.The traditional power flow calculation method of distribution network can not meet the distribution network with distributed generation.In this paper,the distributed power supply model is studied,and the fixed point non expansive power flow algorithm is extended to the power flow calculation of distribution network with distributed generation.The simulation of weakly meshed distribution network and radial network of IEEE33 node is carried out.The simulation results verify the applicability of the proposed algorithm in power flow calculation of distribution network with distributed generation...