Research On Electromagnetic Transient Simulation Of Power Grid With Large-scale Renewable Energy For Low Computing Power Platforms

The renewable energy-based new power system will gradually be built in China.Huge amounts of renewable energy equipment include the complex and fast switching process of a large number of power electronic components,which increases the depth and breadth of the coupling between renewable energy and large-scale power system dynamic response process.Therefore,the traditional electromechanical transient simulation cannot meet the requirements of simulation accuracy;additionally,due to the limitation of simulation scale and calculation time,the traditional electromagnetic transient simulation also needs to improve the simulation ability and calculation efficiency.In order to meet the new requirements of new power system development for simulation tools and solve the problems with the electromagnetic transient simulation of large-scale new energy power grid,based on the idea of “electromagnetic transient simulation combined with electromechanical transient simulation”,this paper studies the key technologies of simulation modeling,initialization and parallel computing,and achieves the following results:1)Aimed at solving the difficulty in acquiring parameters,the complexity of modeling and the heavy computation,which are the problems with traditional electromagnetic transient simulation methods for the simulation of large-scale power grid,based on the idea of component overall modeling,an electromagnetic transient modeling method for power grid with large-scale renewable energy is proposed.The method effectively improves the modeling efficiency.Based on the commonly used power grid parameters,the model focuses on the process which has great influence on the system characteristics.Under reasonable assumptions,the method establishes an electromagnetic transient model of synchronous generator based on engineering parameters and proposes doubly fed wind power model the wind farm equivalent model based on the converter average model,which solves the difficulty with large-scale electromagnetic transient simulation modeling.The simulation results show that the proposed model can accurately reflect the dynamic characteristics of components and is suitable for large-scale electromagnetic transient simulation.2)Aimed at addressing the problem that the traditional electromagnetic transient simulation can only start from zero state,and the initialization process and mode adjustment are time-consuming and laborious,a fast initialization method of electromagnetic transient based on power flow results is proposed,which effectively improves the initialization speed of large-scale electromagnetic transient simulation.The interface and initialization scheme of synchronous generator and doubly fed wind power are designed,which solves the problems about the difficulty with obtaining initial values of state variables and unbalance of the initial values in traditional electromagnetic transient simulation.Simulation results show that the proposed initialization method can realize initialization quickly and smoothly in various scenarios,and is suitable for large-scale electromagnetic transient simulation.3)Aimed at dealing with the problems of low automation and insufficient utilization of parallel computing resources in traditional electromagnetic transient simulation,a parallel simulation idea of “decomposition before combination” is proposed,and a combined optimization task scheduling method based on mixed integer programming model and a sub network topology merging task scheduling method based on Greedy Algorithm are designed,which effectively improves the availability and parallel computing efficiency of large-scale electromagnetic transient simulation.Based on the characteristic that there are many lines which meet the natural decoupling conditions in large-scale power grid,the focus of parallel simulation is shifted to task combination according to the idea of “decomposition before combination”,which effectively solves the problem of high parallel cost of large-scale electromagnetic transient simulation.Simulation results show that the proposed parallel task scheduling method can effectively improve the efficiency of parallel simulation and is suitable for large-scale electromagnetic transient simulation.4)For the lack of electromagnetic transient simulation tools suitable for low computing power platforms of power grid with large-scale renewable energy,an electromagnetic transient simulation program is developed and implemented based on the above innovative achievements,and the full electromagnetic transient simulation of regional power grids with high proportion of new energy based on ordinary computing equipment is realized for the first time.The program has the remarkable characteristics of high modeling automation,fast and stable initialization and high calculation efficiency,and it effectively improves the easy use of electromagnetic transient simulation tools,which is conducive to the promotion and application of electromagnetic transient simulation in new power systems with new energy as the main body.