Small Signal Stability Analysis of Microgrid with Multiple Parallel Inverters

Abstract

Microgrids are introduced into power grid for managing the high penetration of renewable energy sources(RESs). Based on the resistive characteristics of the microgrid line, this paper proposes an inverter control mode combining the outer power loop controller with anti-droop control and the inner voltage-current dual-loop controller. Meanwhile, a complete small signal model of single inverter including anti-droop control, dual-loop control, filter and branch is established. Then considering the coupling relationship of the output voltage phase angles of each inverter, the small-signal model of the microgrid with multiple parallel inverters is established under the global coordinate system. The static stability analysis of the complete microgrid is carried out by the root locus method. Results show that the anti-droop control is more conducive to the accurate distribution and fast response of the active power output by inverter units than the traditional droop control.

Robust microgrids for distribution systems with high solar photovoltaic penetration

“…By linearizing and rearranging the above equations, the small signal model of the DC link can be written in a state-space form as in (12):…”

“…According to the study presented in [20], renewable sources participating in the frequency regulation of a microgrid can significantly improve the dynamics of the microgrid. To improve the power response of the microgrid, a study presented in [12] proposes an anti-droop controller for each converter in the microgrid. Based on the small signal stability analysis, it is demonstrated that inverters integrated with droop control for power sharing provide more room for adjusting the eigenvalues to improve response of the microgrid.…”

“…Recently, many studies have considered the effect of the control parameters on the stability of microgrids with grid-forming inverters [13,16,17]. Additionally, some critical aspects related to practical microgrids have not been considered, such as load profile and solar profile [8,9,[12][13][14]. Furthermore, to the best of the author's knowledge, most studies only analyze the penetration of renewable sources equipped with droop control on the small signal stability.…”

Small Signal Stability Analysis of a Microgrid in Grid-Connected Mode

“…The authors of [13] developed a small signal model of a MG in islanding mode, to analyze the stability and robustness of the MG, and then an adaptive control method was proposed to adjust the control gains in response to disturbances. In [14][15][16][17][18][19][20] the SSS of MGs in islanding mode was studied when controller gains were increased. In [18], the SSS of a MG in islanding mode was resolved, while proposing a method that simultaneously ensures stability and optimal power flow.…”