Research On Fast Decoupled Parallel Computation Of Electromagnetic Transient In Photovoltaic Power Generation Unit

With the proposal of China’s carbon peak and carbon neutrality strategy,new energy represented by photovoltaic and wind power has developed rapidly.In order to study the dynamic characteristics of new energy power systems and design control and protection strategies,it is necessary to conduct accurate electromagnetic transient simulation of the power system.However,when using traditional electromagnetic transient detailed models to simulate photovoltaic systems with a large number of inverters,the problem of balancing simulation speed and accuracy becomes more prominent.In addition,during the design,manufacturing,and control performance verification of equipment in photovoltaic power plants,real-time simulators are required to complete hardware in the loop testing due to cost and experimental safety considerations.However,existing simulation models and algorithms are difficult to meet the real-time and accurate simulation requirements of a large number of power electronics.Therefore,studying offline simulation algorithms for large-scale photovoltaic power generation units and real-time simulation algorithms for photovoltaic power generation equipment that meet simulation accuracy and speed is a key engineering problem that urgently needs to be solved under the "dual carbon"goal.The paper conducts the following research work on the fast electromagnetic transient offline simulation of large-scale photovoltaic power generation units and the real-time simulation algorithm of photovoltaic power generation equipment:(1)Research on fast simulation method of photovoltaic power generation unitBased on the Semi-Implicit Latency Decoupling and Paralleling(SILDP)technology,a semi-implicit delay decoupling model for Boost,VSC converter,LC/LCL filter,and collector line equipment was established.The decoupling of photovoltaic power generation units and photovoltaic power plants was achieved,and the calculation timing and process of the model were designed.The characteristics of the model were analyzed,and an electromagnetic transient decoupling model for photovoltaic power plants was established.By programming,the simulation accuracy and efficiency were compared under different numbers of photovoltaic power generation units,switching frequencies,and simulation steps.The decoupled model of photovoltaic power generation system established in this article not only improves simulation efficiency but also maintains high accuracy when the scale of photovoltaic power plants is large and the system is complex.(2)Research on Synchronous Switch and Multi-switch Processing Methods in Real-time SimulationBy analyzing existing research results at home and abroad and combining with the demand for real-time simulation,a synchronous switch processing method suitable for two-level converters and a Time Average Method(TAM)for processing multiple switches were proposed.The synchronous switch processing method obtains the final switch state based on the physical state analysis of the circuit when it is in a non latching state.During the latching state,the final switch state is determined by traversing and solving for three possible states;The TAM algorithm takes the equivalent average value of the switching function within a simulation cycle based on the principle of equal impulse,so that the integrated waveform does not accumulate errors and improves simulation accuracy.(3)Research on real-time simulation method of photovoltaic power generation equipmentStudied the characteristics of FPGA,including data storage format,decoupled FPGA model design,simulation system architecture design,and coordinated simulation implementation of electrical and control systems.Studied the method of implementing real-time simulation on FPGA chips based on Verilog language,as well as the method of implementing TAM on real-time simulation hardware.A real-time simulation platform based on Xilinx series FPGA chips has been established,and the effectiveness of the proposed method has been verified from the aspects of simulation accuracy,resource utilization,and time performance using a semi-implicit delay decoupled VSC converter circuit as a test example.