Stability of Renewable Energy based Microgrid in Autonomous Operation

Abstract

This paper develops a comprehensive small-signal model of hybrid renewable-energy-based microgrid (MG) in an attempt to perceive oscillatory stability performance and capture the potential interaction between low-frequency critical modes within the MG. Trajectories of sensitive modes due to controller gain variations were evaluated in order to determine the stability boundaries. It was noticeable that various power-sharing schemes significantly influenced the small-signal stability of MG. Moreover, modal interaction emerged due to the proximity of RES-based DG units and non-linear dynamic behaviour of the sensitive modes. The interaction may result in a more oscillatory situation which potentially leads to instability of MG. The low-frequency critical modes obtained from eigenvalues analysis were then verified with the help of nonlinear time domain simulations. The presented work contributes to enhance the design and tuning of controller gain and proposes appropriate power-sharing scheme within MG.

Impedance-Based Interactions in Grid-Tied Three-Phase Inverters in Renewable Energy Applications

“…Equation (36) shows that the output dynamics of the inverter (i.e., the elements (2,1), (2,2) and (2,3) in Equation 24) and the reverse transfer function T io (i.e., the element (1,2) in Equation 24…”

“…According to Equations (23), (36), and (37), we can compute the load-affected transfer functions to be…”

“…The origin of the stability problems in grid-connected systems is usually the negativeincremental-resistor-like behavior at the input or output impedance of the three-phase converter [29][30][31] similarly as in DC-DC converters discussed in References [1,2]. In three-phase converters, the negative-incremental-resistor-like behavior is either the consequence of the grid synchronization [29][30][31][32][33][34][35] or the feedback control from the output-terminal variables [36][37][38][39][40][41][42][43]. In case of grid synchronization, the instability can be mitigated in some extends by lowering the control bandwidth of the phase locked loop (PLL) adaptively when the grid impedance is increasing as discussed in Reference [44].…”

Frequency Response Analysis of a Single-Area Power System with a Modified LFC Model Considering Demand Response and Virtual Inertia

“…In the large synchronous machines, the inherent kinetic energy due to rotor inertia and damping effect due to mechanical friction and electrical losses in machine windings play a significant role in the grid stability. On the other hand, the power units derived by RES have either very small or no rotating mass resulting in degraded inertia and damping properties [1,27,28]. The negative impact of reduced inertia and damping properties on grid's dynamic performance is accelerated when penetration level of RES increases.…”

Feedback-Oriented Intelligent Monitoring of a Storage-Based Solar Photovoltaic (PV)-Powered Microgrid with Mesh Networks

“…A game-theory-based, flexible control of demand using proportional allocation was proposed in [23] for an autonomous grid operation. Emphasizing on the stability of microgrids, Krisminato et al [24] developed a comprehensive small-signal model of hybrid renewable-energy-based microgrid to observe its performance. Since the inculcation of communication makes the smart grid vulnerable to cyberattacks, it is equally important to consider the privacy and security aspects of the grid.…”