Electromagnetic Transient Real-time Digital Simulation Of Photovoltaic Microgrid

Photovoltaic microgrid is a small power system which is composed of load and distributed power source.In order to ensure that the photovoltaic microgrid is of high simulation accuracy and strict real time,multi-rate real-time simulation method of a photovoltaic microgrid system is put forward.This paper analyzes the system simulation model,such as the photovoltaic array,switch of system level,LCL filter,and isolation transformer,and analyzes the control method of chopper and inverter.Explicit Euler method is used to implement differencing for differential equations of the selected inductances and capacitances.The whole grid-connected photovoltaic system is divided into subsystems.The small step length is used to emulate subsystems with power electronical element,other systems use larger simulation step.The calculation sequence of multi-rate simulation is presented.On this basis,the stability criterion of the multi-rate simulation algorithm is put forward.FPGA is used as a platform to build the digital grid-connected photovoltaic system.And the hardware in loop test for DC/DC and DC/AC converter controllers is conducted on this platform.The results show that the digital grid-connected photovoltaic system works properly and data of multi-rate simulation and single rate simulation are basically the same.