Design And Implementation Of Digital AC Power Supply For Integrated Simulation Training Platform

Low-voltage collection operation and maintenance simulation training platform is a multifunctional autonomous collection operation and maintenance training equipment that integrates training and learning,theory verification,practical operation ability,assessment and identification.It is specially designed for the simulation training and learning of the staff who carry out collection operation in the power grid.The digital AC power supply designed in this paper is the core component of the low voltage collection operation and maintenance simulation platform.It can output voltage and current in multiple channels to provide virtual load for the three-phase electricity meter in the platform.The power supply can be divided into two parts:the pre-stage DC-DC transformation and the post-stage DC-AC transformation.The pre-stage DC-DC transformation adopts the full-bridge LLC resonant converter,which not only reduces the volume of the system,but also plays the role of electrical isolation,and reduces the electromagnetic interference of the system.There are six inverter power sources in total,including three-phase voltage source and three-phase current source.The six inverter power sources can be controlled independently.The voltage source output voltage rating of each phase is 220 V,and the voltage range can be adjusted to meet 0-120%.Current source output each phase current rating 5A,current range meets 0-120% adjustable,and the output voltage current has a high accuracy.Based on the application background of digital AC power supply and its main performance requirements,this paper carries out the research and design of digital AC power supply.Firstly,the design scheme of the system is determined,and the topology structure and working principle of the full bridge,flyback,forward and inverter circuits are analyzed.The topology circuit of the whole system is selected,and the modulation technology of the main circuit of the system is determined.In addition,this paper introduces the pre-stage LLC resonant converter and the post-stage three-phase combined H-bridge inverter technology in detail,analyzes the working mode of the LLC resonant converter,and obtains the DC voltage gain curve of the converter through fundamental wave analysis,which provides a basis for the resonant parameter design of the converter below.At the same time,the mathematical model of single-phase H bridge inverter in dq rotating coordinate system is established.After decoupling,it is used for the design of PI double closed-loop controller.Secondly,the hardware design and software design of the system are emphasized.In the aspect of hardware design,the main circuit,DSP controller circuit,driving circuit,detection and acquisition circuit,protection circuit,power supply circuit were designed,and the calculation of related parameters and the selection of devices were completed.In the aspect of software design,the main program of the system,the timer interrupt service program and the ADC interrupt service program were designed,the program was introduced in detail,the program design flow chart was given,and the design program was completed by MATLAB/Simulink code generation technology.Finally,according to the design content,the digital AC power system is made,and the performance of the power system is tested in detail.The test results show that the system design meets the target requirements and achieves the expected effect.