Coupling effect analysis and control for grid‐connected multi‐microgrid clusters

Abstract

The parallel grid-connected inverters are coupled due to grid impedance, which introduces multiple resonances and might lead to instability of the whole system. Hence, considering the coupling effect among inverters and achieving a solution for resonance damping is necessary for designing the control system. With increasing the influence of microgrids, the interconnection of microgrids is inevitable. Therefore, new challenges emerge with the interconnection of microgrids. It can be expected that the impedance of connection lines and grid impedance, play the most important role in the coupling of microgrids. Accordingly, the coupling effect among microgrids should be considered in control system design as well as considering the coupling effect among parallel inverters. Otherwise, the interconnection of microgrids might degrade the quality of grid injected current, while the injected current of each microgrid satisfies the standards when it is individually connected. In this study, the coupling effect between the two interconnected microgrids is investigated. Also, the control system design for inverters considering the coupling effect among parallel inverters inside a microgrid and coupling effect of other microgrid is clarified, elaborately. Several simulations and experimental results on a small-scale laboratory prototype verify the validity of the theoretical analysis and the effectiveness of the proposed scheme.

Stochastic Predictive Energy Management of Multi-Microgrid Systems

“…Considering an exemplary system diagram for M = 4 as represented in Figure 2, changes in I M (t) is equal to the summation of the line flow changes in different lines that connect the MGs to the main grid as shown below. In (30), ∆ f n−m represents the change in power flow of the line n − m, which connects the nth bus to the mth bus. According to [34], it is assumed that any power changes ∆P i at the ith bus of the system will be compensated through an exact opposite change in the reference bus, which is assumed to be the main grid in this study while the power generation in other buses remains fixed.…”

“…Utilizing (30), the change in power flow of the reference line concerning different MGs can be calculated as follows:…”

“…In other words, no analysis is conducted to indicate the applicability of the developed controllers to be incorporated in the full control hierarchy, which can guarantee power system technical requirements. Moreover, there are only a few experimental results in the context of multiple IMGs [29,30]. Besides, the potential of the two-stage stochastic MPC in operation management of MMG systems has not been considered.…”

Trilateral control for LCL filter‐based system with single grid current sensor in weak grid

“…To eliminate the concern, the passive damping technique is used in order to address the resonance issue. Nevertheless, this measure reduces the efficiency [9]. Therefore, the active damping technique which introduces minimum loss is preferred to attenuate the harmonics in the system.…”

Complete decoupling compensation of three‐phase inverter with LCL filter in synchronous reference frame

“…In the control of three‐phase inverter, the AC signals in stationary reference frame are always transformed into DC signals in synchronous reference frame (SRF), which would cause coupling problem of the active and reactive current [1, 2]. In [3], the double‐sided spectrum diagram has been introduced, which can describe the differences of the signals in the two reference frames.…”