Mode‐dependent seamless transfer control strategy of a microgrid via a small‐signal stability approach

Abstract

A microgrid is an effective solution to enhance the integration of distributed renewable energy resources, which can operate both in grid connected mode and islanded mode. In order to reduce the jumps of the system variables within acceptable limits to ensure the system has good transient performance and power quality in multiple operating modes, seamless transfer is the key problem to be considered. In this paper, due to the different multiple equilibrium points for the two operating modes, the dynamics of every operating mode re modeled as a subsystem with all the variables that are needed to be synchronized. Linearization is carried out respectively for the two operation modes on the different equilibriums in a state-space form based on the small-signal stability method. To reduce the conservatism of the unified controller, the concept of the relative Lyapunov function is introduced to derive a multiple segmental Lyapunov method and a robust feedback mode-dependent switching controller is designed to achieve smooth transfer by making the deviation energy of the two modes both converge to the zero point. To rapidly detect the switching signal, a sparse communication network is introduced by the use of low bandwidth communication links to broadcast the switching signal to each distributed controller. Finally, two microgrid test systems were built in SIMULINK to show the feasibility and effectiveness of the proposed seamless transfer control strategies.

A distributed event‐triggered dynamic average consensus scheme with a time‐varying threshold and its application in DC microgrid

“…With Assumption 1, the result that 𝜏 T L = 0 comes. According to (6) and 𝜏 T Π N = 0, we take the derivative of z…”

“…In this scenario, agents are required to track a dynamically varying signals [1,2], thus rendering the static consensus control techniques inapplicable. In recent years, DAC has drawn considerable attentions due to their potential applications in a variety of disciplines, such as smart grid [3][4][5][6][7], formation control [8], and distributed optimization [9]. The topic of DAC is both theoretically and practically significant.…”

Bumpless Optimal Control over Multi-Objective Microgrids with Mode-Dependent Controllers

“…To enhance the integration of large-scale renewable energy sources, control strategies need to consider both the operation modes and transition behavior to guarantee the continuous stability of microgrids in different status, especially the transient jumps when mode changes occur [3]. Therefore, how to reduce the jumps of the system variables and improve power quality in mode transient behaviors is quite essential and is a very significant research topic [4,5].…”

“…Thus, this method is not flexible for different system structures. In addition, the controller parameters are generally obtained through experiments, so a theoretical basis is not sufficient for further research [5]. Therefore, although the sudden peak of current and voltage during the transition process has been restrained, the discontinuity problem of control inputs at the switching time has not been substantively solved, which is focusing on the bumpless control technology to really smooth the control signal during the process of mode transfer.…”