Multi-rate Electromagnetic Transient Simulation Of Power System Based On Multicore CPU

With the development of the power system,in order to improve the stability and economy,enhance the control of the power grid,High Voltage Direct Current,Flexible AC Transmission Systems,power electronic devices such as large-scale new energy power generation are widely used in power systems,making EMTP based on detailed modeling and small steps becomes the most important power system analysis tool.When simulating the fast transient characteristics of power electronics such as HVDC and FACTS,or the waveform distortion caused by some non-linear elements,or studying the local network fault process,control method and its rapid influence on the whole system operation,only electromagnetic transient simulation can correctly reflect the original information of the system.However,in the actual simulation process,due to short simulation step of the traditional electromagnetic transient and the complexity of the simulation model,resulting in slow simulation speed,and the simulation scale is not large.At present,the level of computer hardware is improving,the popularization and application of multi-core CPU personal computers is a great revolution under way.However,the existing electromagnetic transient simulation software can not automatically parallelize to take full advantage of the convenience brought by multi-core CPU.The synchronous generator is an important part of the power system.In this paper,the existing electromagnetic transient model of synchronous generator is introduced in detail.Based on this,an improved model of synchronous motor is proposed.This model can effectively reduce the difference error and has better simulation accuracy.According to the Shannon sampling theorem,the simulation step size of power system digital simulation is related to the simulation signal frequency.The lower the signal frequency is,the larger the simulation step size can be taken.Rotating down-conversion is one of the effective methods to reduce the signal frequency.In this paper,the long step electromagnetic transient model of synchronous generator and long transmission line is deduced based on rotating down-conversion method.Based on this,a multi-rate simulation method is proposed in this paper.In order to improve the speed of electromagnetic transient simulation and expand the simulation scale,this paper proposes a simulation strategy that combines multi-rate and parallelism.For the part that wants detailed simulation,the traditional electromagnetic transient model is used to simulate with short step size.The rest part is simulated with long step size by using the long step electromagnetic transient model based on the rotating transformation deduced in this paper.Each of the two part system can be further parallelized into subsystems to take full advantage of the multicore CPU.Finally,the simulation of this paper verifies the accuracy and speed of the proposed simulation strategy.