Research On Fault Location Of Distribution Networks With Distributed Generation

Accurate fault location in an electric power distribution system is important in maintaining power system reliability.Several methods have proposed in the past.However,there has been great interest in the integration of distribution generation units at distribution networks,such as PV,Wind,and so on.These unconventional generation change the power flow in distribution networks from unidirectional flow to multidirectional flow and thus change the fault signals amplitudes.In these circumstances,the traditional fault location methods are no longer suitable for distribution networks with DG and new fault location methods should be presented aimed at considering these changes.In order to realize the accurate fault location of the distribution networks with DG,this paper combines the fault section location with the fault indicator to determine the fault section or fault branch,and then combined with the impedance-based method for fault location.The main research contents are as follows:This paper first studies the relevant standards of various DG access to distribution networks,and summarizes the general principles of DG access to distribution networks.The short circuit current characteristics of different types of DG are simulated and the calculation method of fault current are introduced.Also,the influence of different positions of DG on relay protection and fault location are analyzed.Then,the power flow calculation model and steps of the distribution networks are studied.The impedance-based method is proposed,and it is applied to the distribution networks with DG.The network model is established in MATLAB to simulate.Because the traditional matrix algorithm can not correctly locate when the FTU fault information is distorted,the improved fuzzy genetic algorithm is proposed to locate the fault section.In this paper,the switching function and the fitness function are improved,and the crossover and mutation operators in the evolutionary process are adaptive adjust in the use of fuzzy control theory,which avoids premature convergence and improves the accuracy of optimal individual.Finally,the improved algorithm is used to simulate the fault location of distribution networks with DG in MATLAB,and the feasibility and fault tolerance of the algorithm are verified from various aspects.It also puts forward a general framework idea on how to implement the fault location scheme proposed in this paper in engineering practice.