Extra transient block for virtual synchronous machine with better performance

Abstract

An extra transient block (ETB) for virtual synchronous machine (VSM) that is able to provide extra transient dampingand adjust transient inertial to better stabilise the frequency of the VSM in a shorter time during transient period without alteringthe steady-state performance is proposed in this study. The ETB uses extra parallel series lead-lag blocks to get the transientfrequency output to make the stability of the VSM less intensive to the parameter design of the virtual inertial and dampingcoefficient so that an easier parameter design method can be used. In other words, this method helps to solve the contradictionbetween dynamic response and stable performance, especially when the damping coefficient cannot be freely modified toincrease damping for a large inertial value because of the mutual dependence between damping coefficient and droopcoefficient caused by the use of inner reference frequency. Moreover, a simplified method for the parameter design of the ETB isproposed and the small-signal model of the ETB-based VSM is also derived. After that, the power coupling situation is analysedand comparisons with other control strategies are presented. Furthermore, time-domain simulation results are demonstrated toverify the effectiveness of the proposed method.