Research On Digital-physical Hybrid Simulation System For Research Of Distribution Network Protection

Rapid development of social economics has placed greater demands on power system.With wider application of distributed renewable energy and DC power supply technology,distribution network protection faces more and more challenges.And an advanced simulation platform is necessary for the development of new distribution network protection.This paper discusses the digital-physical hybrid simulation system for research of distribution network protection,and researches on protection schemes of different distribution networks as well as realization methods of digitalphysical hybrid simulation systems.In this paper,firstly,the digital-physical hybrid simulation system for research of distribution network protection is studied.A three-layer structure of digital-physical hybrid simulation system is proposed,and different interface modules in simulation system are studied.Also,to adapt to flexible operation of distribution network,a hybrid simulation method for different types of real-time digital simulation devices is proposed and verified by simulation.Based on the structure proposed,three typical cases,including islanding detection,distributed generation protection,and shipboard DC distribution network protection,are studied.Firstly,a method of intelligent islanding detection simulation system with incremental learning capability is proposed.Then,the control strategy and digital simulation method of inverter interfaced distributed generation(IIDG)are studied.A real-time digital simulation system for research of IIDG control strategy is proposed.Flexible positive and negative sequence current control strategy and its optimization method are proposed,which can take into account the requirements of fault ride-through,relay protection,and fault analysis.Control process and realization method of IIDG are analyzed,and effectiveness of control strategy is verified by simulation.Based on this strategy,the IIDG equivalent sequence network model is proposed,and the adaptability of traditional directional negative sequence components to distribution network with IIDG is analyzed.Finally,the digital-physical hybrid simulation system for research of shipboard DC distribution network protection is studied.The protection configuration scheme and all-digital protection system for shipboard DC distribution network are proposed.To reduce the occupation for real-time digital simulation resources,the real-time digital simulation model based on large time step,including generator-rectifier and DC circuit breaker,is proposed and verified by digital simulation.Finally,the digital-physical hybrid simulation system for research of shipboard DC distribution network protection is further proposed,and the digital simulation model is verified by hardware-in-loop experiments.