Study On Electromagnetic Transient Simulation Method For Voltage Source Converter

With the rapid development of technologies such as direct current transmission and new energy generation,the prominent feature of new power systems dominated by new energy is power electronics.Electromagnetic transient simulation is one of the indispensable technical means for effectively analyzing the operation rules of new power systems and ensuring the economic,safe and stable operation of power grids.Voltage source converter(VSC)is widely used in new energy generation and flexible DC transmission systems.With the extensive application of VSC in new energy stations and flexible DC transmission systems,new challenges have emerged in electromagnetic transient simulation of power systems.Therefore,the research on electromagnetic transient simulation models of VSC has become a hot topic.In this paper,the following main work has been carried out for the electromagnetic transient simulation model algorithm of VSC:(1)The current basic algorithms for electromagnetic transient simulation of VSC have been studied.When the simulation step size is inconsistent with the switching action time,smaller steps are usually used or the double interpolation method(DIM)is used to modify simulation related parameters.Through analysis,it is found that these methods will have a negative impact on the accuracy and speed of the simulation solution.(2)This paper proposes an improved electromagnetic transient simulation method for VSC.A semi implicit latency decoupling method is applied to simulate the VSC.By splitting its system matrix,the entire system state variables are divided into two groups.For the control system of the circuit,considering the special state of multiple switching actions within the simulation step,the trapezoidal integration method is used to correct the control signal to an equivalent duty ratio based on the effective area of the step occupied,thereby effectively solving the above problems.(3)Applying the proposed improved method,a simulation model of the VSC is established,and the method is verified to have higher accuracy and faster speed through simulation,which proves its validity.This improved method can keep the system admittance matrix constant while taking into account the switching actions within the simulation step size,without the need to store multiple simulation steps in advance,and without changing the simulation step size and switching the integration method throughout the entire simulation process,thereby improving the accuracy and speed of simulation.