| With the development of power grid construction,distributed power supply is widely used in distribution system.However,the integration of Distributed Generator(DG)will cause bidirectional change of power flow in distribution network,which will reduce the accuracy of traditional fault line selection and fault segment location methods and even fail.Therefore,it is necessary to further study the method of fault line selection and segment location in distribution system after the integration of distributed power supply into distribution network to ensure the operation safety of distribution network with distributed power supply.The control principle and fault characteristics of Inverter Interfaced Distributed Generator(IIDG)are analyzed theoretically.The model of medium voltage distribution system with inverter distributed power supply is built on PSCAD software,and its rationality is verified by simulation.Aiming at the problem that the existing fault line selection methods for distribution networks with IIDG cannot accurately select lines under various fault types,the combined modulus current transformation is introduced to eliminate the failure of fault characteristics under different fault types.The combined modulus traveling wave current of each line is S-transformed,and the energy entropy of each outgoing line is calculated by the short window data at the maximum value of the fault signal.Finally,the entropy value is compared to judge the fault line.On the basis of fault line selection,fault segment location is further studied.Aiming at the situation that the traditional fault location method using electrical quantities fails after the IIDG is connected to the grid,the theoretical analysis shows that the difference of the combined modulus current waveform at the head and end of the fault section is significantly larger than that of the non-fault section.Then,a fault location method of active distribution network based on combined modulus S-transform relative entropy is proposed.A segment location model with IIDG distribution network is built on PSCAD for simulation verification.The results show that the method can accurately select the fault segment under various fault types,and has a certain anti-noise ability,and has a good tolerance to the fluctuation of IIDG output power.Aiming at the situation that the fault location method using artificial intelligence algorithm has low location accuracy and poor fault tolerance,a fault location method of distribution network based on improved sparrow search algorithm is proposed.The accuracy of distribution network fault location algorithm is improved by improving finder’s search strategy and forewarning’s movement rule.Finally,the simulation model of active distribution network with distributed power supply is established,and the simulation experiment of fault location of distribution network is carried out,and the feasibility of sparrow search algorithm in fault location of distribution network with IIDG is verified.The simulation results show that the proposed method can adapt to IIDG switching in distribution network,and has high search speed,strong fault tolerance,high precision,and strong practicability. |
