Kongzhi Yu Xinxi Jishu (Apr 2022)

Simulation Research of Virtual Synchronous Machine Control System with Harmonic Suppression

  • CHENG Kun,
  • DING Xiying,
  • GONG Jingying,
  • HAN Yan,
  • LI Xiaodong

DOI
https://doi.org/10.13889/j.issn.2096-5427.2022.02.500
Journal volume & issue
no. 2
pp. 22 – 28

Abstract

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Virtual synchronous machine control strategy is an effective means to solve the problem of inertia lack in grid connection of new energy source, but oscillation link in control system makes harmonic content of the connection process of distributed power grid higher and the composition more complex. Aiming at the problem of harmonic analysis and suppression of virtual synchronous machine control system, a crossover droop harmonic suppression strategy based on virtual synchronous machine control is presented in this paper. Virtual synchronous machine control mechanism is firstly reviewed, the characteristics of system harmonics under nonlinear load conditions are simulated and analyzed. High-slope droop control is performed on the main harmonic components of each order to quickly clean up the harmonics output of grid-connected inverter, so that the inverter has the ability to suppress specific harmonics while transmitting power. Simulation model of the virtual synchronous machine control system is built on a Matlab/Simulink simulation platform, and the third and fifth harmonics in the system are extracted respectively for harmonic droop control. The output of each harmonic droop control is superimposed with the output of fundamental wave domain virtual synchronous machine control to obtain the input of the inverter, stability of the system is analyzed, and droop coefficient that satisfies stable operation of the system is selected. Simulation results show that the system has no power mutation behavior during grid-connected process of distributed power generation, and the grid-connected inertia of the virtual synchronous machine control system is well realized. Compared with the traditional control strategy of inverter, it has better harmonic supression characteristics that the voltage harmonic content decreases from 31.36% to 3.91%, and the current harmonic content decreases from 50.24% to 7.04%.

Keywords