Electromagnetic Transient-Transient Stability Analysis Hybrid Real-time Simulation Method Of Variable Area Of Interest

Real-time(RT)simulation means that the time that is required by the simulation platform to complete the computation of state outputs for each step size is shorter than or equal to the selected step size,which can be used for design,prototype construction,hardware-in-the-loop testing,teaching,and training.Although electromagnetic transient(EMT)simulation is considered to be more precise,its simulation calculation burden is heavy,which limits the simulation scale.Although transient stability analysis(TSA)simulation sacrifices the description of fast transients,harmonics,and electromagnetic nonlinearities,it has the advantage of large system analysis.When the computational resources of the large-scale power system for EMT simulation are insufficient,a feasible solution is that the part requiring detailed study performs EMT simulation and the rest perform TSA simulation.Both are connected through an interface.Following the research object being carried out to network partitioning in the existing works,the areas of EMT simulation and TSA simulation are often fixed.To make the object of EMT simulation flexible to change,the current authors propose using the method of EMT-TSA hybrid real-time simulation of the variable area of interest.The area where the fault is to be set,or where the operation takes place is defined as the area of interest.That is,according to the difference of interest areas,EMT simulation of different areas is performed in different periods,and TSA simulation is performed on all areas.The simulation object is divided into multiple sub-networks.The EMT simulation range is determined according to the voltage drop depth at the boundary of the adjacent sub-network caused by the three-phase short-circuit fault at the boundary of an area of interest.According to the characteristics of a hybrid real-time simulation of variable area of interest,the Norton equivalent is obtained by using the sub-network as a basic unit.The calculations on the electromagnetic side and the TSA side mainly include three steps.Based on this,a general model of the contact system is constructed.The contact system consists of the Norton equivalents of electromagnetic sub-networks and the Norton equivalents of the TSA models of the remaining sub-networks.The electromagnetic sub-network forms its own Norton equivalent model on the TSA side by means of the positive sequence components of voltage and current that are extracted by the discrete sequence at its interfaces and the Norton equivalent admittance of its TSA model.Looking at the problem of large interface error in the parallel data interaction mode,which is caused by the use of the previous time-step equivalent parameters on both the TSA side and the electromagnetic side,the fundamental phasor prediction and Norton equivalent current source prediction are adopted to reduce the interface error.The performance of the proposed method in terms of feasibility,flexibility and effectiveness have been verified by the simulation studies on the IEEE 118-bus system.