Low-Dimensional Equivalent Models and Multithreading-Based Parallel EMT Simulation Method for Multi-Converter Systems

As the proportion of renewable energy generation in the grid increases, the number of voltage source converters (VSCs) has grown significantly. It is therefore of great importance to study the multi-VSC systems using electromagnetic transient (EMT) simulation. This paper presents a novel approach to modeling multi-VSC circuits, comprising EMT low-dimensional equivalent models and a multithreading-based parallel simulation method. The decoupling between the VSC from the AC grid is initially achieved through the adoption of semi-implicit hybrid integration. This is followed by the synthesis of the equivalent circuit for each phase, which results in the derivation of low-dimensional equivalent models of multi-VSC circuits. In addition, a parallel simulation algorithm for the VSC is proposed, which enables parallel solution and the update of internal/external node voltages and historical current sources. Subsequently, the design and implementation of the parallel algorithm is achieved by means of an OpenMP-based simulation framework. Furthermore, a physical experimental platform is established. The simulation results demonstrate that the proposed model is capable of achieving more than 80 times acceleration in serial mode due to the decoupling and low-dimension when applied in a grid-connected 100-megawatt photovoltaic power station (PVPS), and can obtain 2-3 times secondary acceleration in parallel mode with almost uncompromising accuracy.