Research On Real-time Simulation For Micro-grid Based On FPGA

Real-time digital simulation system plays an important role in power system planning and designing,operation scheduling,protection and control testing.There are high switching frequency AC / DC,AC / AC,DC / DC converter in the micro-grid,which puts forward higher demands on the computing power of micro-real-time simulation platform.FPGA(Field-Programmable Gate Array)has parallel hardware structure which can achieve highly parallel numerical calculations,so FPGA has attracted much attention.Faced with the problems of limited simulation scale brought by high-frequency switching devices in real-time simulation of micro-grid and the challenge of high threshold of development and difficult universal design.The detailed work is summarized as follows:(1)The theoretical basis of micro-grid real-time simulation is introduced,including the mathematical model of distributed power supply,power electronic switching devices,transformers,lines and loads.The calculation procedure of node analysis method is introduced.The mathematical integral method commonly used in node analysis method and the least degree method and the maximal independent set method used in solving linear equations are analyzed in detail.A multi-rate simulation method based on substitution theorem is studied.The inductance and capacitance are equivalent to current source and voltage source respectively,so that the whole system is decoupled and the subsystems can be completely solved in parallel.(2)A novel real-time simulator for micro-grid based on FPGA is designed.The real time solver and the order generator in the real-time digital simulator based on FPGA and orders(FO-RTDS)are to be optimized.The data inflow/outflow Ping-Pong circuits of various rhythms and the inflow/outflow operation tasks with time stamps make it possible to realize the overall arrangement of multi-rate simulation task.To reduce the computational pressure,the addressing of multi-valued parameter is integrated into the processing procedure of order by converting the guide word address to the current value address.Based on the task scheduling strategy of prioritizing the last scheduling time,the k-center point algorithm is used to initialize the allocation of the non-intermediate variables and the data scheduling is carried out following the principle of saving the resources and the minimizing the average distance between variables.(3)A hardware-in-the-loop is constituted by the novel FO-RTDS,the real converter controller and relay protection devices.The simulation result is compared with the offline commercial electromagnetic transient simulation software PSCAD / EMTDC,which validates that the novel FO-RTDS is able to realize multi-valued parameter prestorage and multi-rate simulation,which greatly improves the scale of real-time simulation of micro-grid.