Dynamic Phasor Based Interface Model for EMT and Transient Stability Hybrid Simulations

Abstract

Electromagnetic transient (EMT) and transient stability hybrid simulations are predominantly used to analyze the interactions between HVDC systems and the ac grids. However, the dynamics of the converters will be greatly affected by the waveforms of adjacent ac systems. Waveform distortion as well as time delay caused by interfacing can significantly increase interface errors, resulting in the decrease of the overall accuracy of the simulations. To solve such problems, a dynamic phasor based interface model (DPIM) is proposed in this paper to improve the accuracy of interfaces, especially when the fault occurs near the converters. In doing so, the whole system is partitioned into three parts: the transient stability (TS) subsystem, the EMT subsystem, and the DPIM. During each iteration, the interfaces between the TS subsystem and DPIM are represented by their Norton equivalents at the fundamental frequency and Thevenin equivalents in the dynamic phasor form. Similarly, the interfaces between DPIM and EMT subsystems are represented by their three-phase Norton equivalents and Thevenin equivalents in dynamic phasors, respectively. The effectiveness concerning the accuracy and the efficiency of the proposed method is validated by simulating a practical HVDC Project.

Hardware-in-the-Loop Simulation Using Real-Time Hybrid-Simulator for Dynamic Performance Test of Power Electronics Equipment in Large Power System

“…Although a large-scale power system modeling and simulation are useful, it is less flexible than hybrid simulation as power systems become more and more complicated, and as renewable energy resources increase. That is the reason that hybrid simulation and co-simulation has been developed and expand their applications [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Hybrid simulation improves accuracy because equivalents, which represent areas of non-interest in the power system, do not completely show the responses of the actual power system.…”

“…A hybrid simulation is a powerful tool because power electronics applications in the power system require detailed studies with Electro-Magnetic Transient (EMT) simulation investigating the performance of the equipment, and electric utility also has needs of dynamic investigation in the large power system [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Although many hybrid simulation methods and tools exist, improving the accuracy and efficiency of a large power system simulation, those hybrid simulation tools are based on non-real-time.…”

Improvements to the Co-simulation Interface for Geographically Distributed Real-time Simulation

“…A co-simulation of multi-area power systems was investigated in [7], which dealt with the requirement of large-scale simulation resources using real-time simulation at multiple institutions and the confidence for their grid models. In [8], a GD-RTS of HVDC systems were implemented using Ideal Transformer Model (ITM) Interface Algorithm (IA). This work showed that simulation fidelity is robust with large time delay.…”

Multi‐rate co‐simulation of power system transients using dynamic phasor and EMT solvers

“…Co-simulators may use parallel processing and multi-rate techniques [13] to accelerate their computations. Recent developments in co-simulation are reported in EMT-TS co-simulation [14][15][16][17][18], EMT-dynamic phasor (DP) co-simulation [19][20][21], and EMT-DP-TS co-simulation [22]. Common problems with these models and algorithms include, but are not limited to, (i) reduced accuracy of the overall simulation when disturbances occur near the interface, (ii) possibility of one time-step delay between decoupled systems, (iii) inaccuracies of interaction in the presence of high-frequency waveforms, and (iv) lack of control on the simulation's computational burden.…”