Research On Technology Of Real-time Simulation For Micro-grid

Real-time simulation of power system is an important means for electric power system planning,experimental research and evaluation analysis.The development of micro-grid puts forward higher requirements for computational capability.The new digital hardware FPGA has the ability of large fine-grained parallel computing.Faced with the problems of micro-grid real-time simulation,such as non-linear,rigid and high-frequency characteristics of switch plus the challenges that FPGA has limited physical resources,long development cycle,difficult universal design,the work of this dissertation emphasizes on micro-grid real-time simulation algorithm and a real-time simulation system for micro-grid,which is developed based on FPGA.The detailed work is summarized as follows:(1)A block hierarchical parallel method for real-time simulation of micro-grid based on multiport network equivalent is proposed to ensure the accuracy of real-time simulation and reduce the amount of data stored in inverse matrix.Through the distributed power,power electronic devices linear modeling,multiport network equivalence principle is used to establish the exterior characteristic equation and backward equation.A method of maximal independent set combined with the minimum number of ports by considering serial-degree increments is used to determine sub-network hierarchical merge order to improve computational efficiency.(2)In order to improve the scale of real-time simulation and promote multi-platform combined simulation,a multi-rate parallel real-time simulation method based on the latency insertion method and asynchronous interaction method is proposed.Power network is divided into backbone network and distributed generations network by the local latency insertion method and multi-rate interaction of interface electric parameters is implemented by the fitting method and the extrapolation method in parallel.With the goal of using the simulation data of opposite side as soon as possible under the limitation of max communication delay,an asynchronous interaction method is adopted to reduce the influence of communication delay on simulation accuracy.(3)In order to improve the speed of real-time simulation,a method of fine granularity parallelization of FPGA is proposed.A variable-structure processing unit composed of multiple basic arithmetic unit is designed based on data buffer mechanism,and a multiple arithmetic components framework based on the distributed store structure and exchange station is designed.The parallel instruction of any expression can be achieved by instruction stream.The task scheduling algorithm based on generic algorithm and the task scheduling algorithm based on table scheduling are proposed to optimize the generation of instruction streams.(4)A micro-grid real-time simulation system based on FPGA is developed and the results of simulation are compared to the offline commercial electromagnetic transient simulation software PSCAD/EMTDC.The comparison results verify the correctness and feasibility of real-time simulation system developed in this paper.With SPF optical as the medium of communication,a multi-FPGA real-time simulation system has been built successfully,which verifies the feasibility of the proposed multi-rate real-time parallel simulation algorithm.The work of this dissertation lays the foundation for forming a heterogeneous simulation system based on the FPGA and RTDS real-time simulation system.