| The physical design of power system requires a lot of physical and financial resources,and it is not realistic to build a large-scale power system in the laboratory.Therefore,most of the current power system simulations are based on Matlab,RTLAB,PSCAD and other software,which have certain limitations from actual engineering.Sex.Aiming at the current situation of power system experiment software simulation,this paper designs a power system simulation experiment based on hardware-in-the-loop simulation,and proposes and studies the centralized layout structure of sub-modules and a new type of predictive protection power switch device protection control strategy..The semi-physical simulation experiment of low-voltage direct current transmission is carried out,and the equivalent scaling is carried out after the energy and capacity ratio remain unchanged.The background of the ±160kV DC transmission project in South Australia is studied.The equivalent calculation of the line is studied in the background of the Zhangbei DC transmission line.The main research contents are as follows:(1)Taking the half-bridge and full-bridge MMC topology as an example,the basic working principle of MMC is explained.Based on the basic structure of the basic unit of MMC,the working principle and mechanism of the sub-module are explained,and the working principle and mechanism of the three-phase MMC are extended.Based on the comparison of various modulation methods of MMC,the paper adopts the comparison.The modulation mode of NLM;the mathematical model of MMC is analyzed and the structure of input and output is studied,which lays a theoretical foundation for the design of the algorithm;the voltage modulation ratio,fundamental characteristics,harmonic characteristics and range of steady-state operation are studied,and the system is analyzed.Characteristic indicator.(2)Research and propose a new type of sub-module centralized layout structure,that is,a controller board is connected to multiple half-bridge or full-bridge main circuits at the same time to achieve synchronous control at higher speeds.Firstly,the selection of the number of sub-modules and the control frequency on the bridge arm is studied from the theoretical point of view.The selection method of the capacitor and the power device is also introduced.On this basis,the number of sub-modules,control frequency,capacitance and power device are determined according to the design capacity requirements.Selection;according to the characteristics of MMC and power grid,select reactor and connection transformer;study the generation and calculation method of loss according to the choice of circuit device;design hardware of hardware and control circuit of main circuit according to theoretical research;according to the control principle of MMC and existing The hardware circuit is designed with corresponding control algorithms.(3)Research and propose a protection control strategy for power switching devices,and experiment and explain with MOSFET as an example.Firstly,the drive circuit and feedback acquisition circuit are designed according to the structural characteristics and principle of MOSFET.The principle of fault diagnosis and protection is studied.The design idea based on grey prediction model is proposed.The principle simulation experiment is carried out by MATLAB.The hardware circuit is built on the basis of simulation experiment.And through the System Generator,the simulation verified code generation ISE code is burned to the FPGA and the experiment is performed on the hardware circuit.The experimental results are consistent with the simulation results,and the effect is good. |
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