Development And Application Of HVDC Simulation Platform

High voltage direct current transmission(HVDC)plays a key role in solving the problem of uneven distribution of energy and load in China due to its low transmission cost,long transmission distance,large transmission capacity and low loss.In the research and recurrence of HVDC engineering faults,HVDC physical simulation device is an important tool for scientific research.Physical simulation device can better simulate the non-linear characteristics of electronic devices and the interaction between the transmission system and the power system.Based on Jiuhu ±800 kV HVDC project,this paper aims to develop a simulation platform for HVDC physical simulation.By reducing Jiuhu ±800 kV HVDC project in a certain proportion,the normal start-up,shutdown and operation of HVDC system are simulated to reproduce the failure of HVDC commutation,and a method to suppress the failure of HVDC commutation is proposed.The main research work and innovations of this paper are as follows:(1)Firstly,this paper introduces the topological structure of HVDC transmission system,the development status of control and protection system and its physical simulation platform,the differences between digital simulation and physical simulation systems is compared,the urgency of physical simulation platform for HVDC transmission is analysed.Then the hardware structure of the physical simulation platform and the overall design scheme of the auxiliary hardware equipment are put forward.In this paper,the main structure of the hardware platform,such as converter,AC system,converter transformer,AC filter and smoothing reactor,is designed and selected firstly.Then,the control circuit of the relay protection device is designed and the main structure of the platform is preliminarily built.Then,the auxiliary hardware structure of the platform,such as heat dissipation and ventilation device,current and voltage sensor,is designed.It enriches the hardware structure and functions of the platform.(2)According to the hardware structure of the platform,the detailed design scheme of HVDC transmission control and protection system is proposed in this paper.The minimum trigger angle control and fixed-voltage control of rectifier station are analyzed emphatically.UI fixed-voltage control and fixed-turn-off angle control of inverter station are also analyzed.the main control methods of platform are simulated and verified by PSCAD simulation software.and the converter transformer,converter valve group and AC bus are designed according to the requirements of repeated test of commutation failure.The relay protection device is installed.The scheme restores the control and protection system of HVDC,and provides a software basis for better simulation ofHVDC operation and recurrence of commutation failure.(3)According to the hardware structure of the simulation platform and the control and protection system,the simulation platform is tested and validated.The correctness of the hardware structure and the control-protection system is verified.The experiments of single-phase and three-phase ground faults are carried out,and the commutation failure phenomenon is reproduced.The specific process of commutation failure caused by harmonic voltage is analyzed.A turn-off angle incremental control method is proposed to suppress the commutation failure caused by harmonic voltage,and the suppression process of commutation failure is successfully reproduced by using the simulation platform.Experiments show that the platform successfully simulates the operation of HVDC system,and repeats the commutation failure of HVDC system many times.On this basis,a method to suppress HVDC commutation failure is proposed and verified.The platform can provide a platform basis for the analysis of commutation failure mechanism and the research of prevention methods of HVDC system,and has a certain value for the recurrence and prevention of HVDC project operation faults.