Service Restoration Technology And Verification For Distribution System Based On Distributed Generation

In recent years,blackouts caused by power system failures occur frequently.In order to deal with this problem,the construction of "resilient power grid" has been put on the strategic level.Distribution network is the most closely connected part of the power system with users.Improving its recovery capability will significantly improve the resilience of the power grid.Therefore,the fault recovery of distribution network is particularly important.With the increasing penetration of distributed generation in the distribution network,its distributed characteristics provide ideas for the distribution network to use it for fault recovery to improve the grid resilience.At present,the characteristics of low inertia of distributed generation are rarely considered in the fault recovery methods based on distributed generation,and these characteristics will have a great impact on the recovery process,and even make the system lose stability again.Therefore,it is very important to study the control technology of distributed generation in the process of fault recovery.In view of the above problems,this paper mainly carries out the following work:(1)The factors that affect the performance of distribution network fault recovery process are analyzed.Firstly,the electromagnetic transient simulation model for islanding recovery of distribution network is established,and the dynamic process which has the greatest impact on fault recovery is simulated by setting a case.Based on this,the influencing factors and mechanism of fault recovery process are analyzed,which lays the foundation for the following control methods.(2)An adaptive backstepping control method based on virtual synchronous machine technology is proposed.Aiming at the possible adverse effects of operations that affect the performance of fault recovery process,the existing control method is improved.A quasi-synchronous control method is introduced to solve the problem of power closing in different periods.Aiming at the problems of lack of inertia and poor anti disturbance ability of distributed generation,an adaptive backstepping control method based on virtual synchronous machine technology is proposed.This method can further improve the dynamic performance of recovery process on the basis of virtual synchronous machine technology.(3)Based on digital simulation and hardware in the loop experiment,the effectiveness of the fault recovery process control method is verified.Firstly,the digital simulation model is built in Matlab / Simulink to verify the fault recovery process control method proposed in this paper,and the RT-LAB simulation platform is used for simulation verification.Finally,the hardware in the loop experiments are carried out on RT-LAB platform and DSP development board to further verify the above control methods.