Distributed cooperative control methods are widely used in the islanded microgrid control system. To solve the deviation of frequency and voltage caused by the droop control, it is necessary to recovery the frequency and voltage to the rated value using a secondary control strategy. However, the traditional communication method relies on the continuous periodic one, which makes the communication burden of the islanded microgrid system heavy and conflicts with the actual operation of the power grid. Using the secondary recovery control method based on the distributed event-triggered method, we conserve communication resources by reducing the number of transmissions of sampled data and achieving the recovery control of the frequency and voltage and the original proportional sharing of active power. In addition, we analyze the stability of the distributed event-triggered strategy and build a microgrid system with MATLAB/Simulink to verify the effectiveness of the control method. Furthermore, we compare with a traditional periodic communication system and demonstrate the superiority of our distributed event-triggered approach.

For the problem of power allocation in microgrid hierarchical control, a distributed hierarchical control strategy based on consensus algorithm is proposed. When the load suddenly increases, due to the different adjustable power of different distributed generators (DGs), overcharging and discharging of DGs will result if the increased load is not redistributed. The distributed hierarchical control strategy proposed in this paper defines the proportion between the local increased load and the local adjustable power as the response ratio. With the objective of ensuring that the frequency and voltage of the microgrid can be restored to their rated value, the response ratios of DGs are adjusted by applying the consensus algorithm. Further, the microgrid realizes the reasonable operation of the microgrid by dynamically distributing the increased load in real time. Finally, the feasibility and effectiveness of the proposed strategy is verified by analyzing the stability of the system and building a microgrid simulation model in the Matlab/Simulink simulation platform.

This article proposed an optimal-consensus-based even t-triggered control strategy to coordinate multiple distributed generators (DGs) in an alternative current (ac) microgrid. The proposed control strategy integrated the average bus voltage recovery and the proportional reactive power sharing by turning the coordinated control problem into a convex optimization problem, which realized the bus voltage control and proportional reactive power sharing of the DGs in one controller so that the controller structure is significantly simplified. Accordingly, the controller provided an asynchronous event-triggered mechanism considering the finite availability of communication resources, which reduces communication burdens and avoids Zeno behaviors. The sufficient conditions are demonstrated using the Lyapunov function for maintaining the stability of the proposed control strategy. Several simulations are exhibited using the MATLAB/Simulink platform and the results are reviewed to validate the effectiveness of the proposed control strategy for enhancing the ac microgrid robustness and reducing communication burdens.

The large-scale electric vehicles connected to the microgrid have brought various challenges to the safe and economic operation of the microgrid. In this paper, a hierarchical microgrid dispatching strategy considering the user-side demand is proposed. According to the operation characteristics of each dispatch unit, the strategy divides the microgrid system into two levels: source-load level and source-grid-load level. At the source-load level, priority should be given to the use of the renewable energy output. On the basis of considering the user demand, energy storage, electric vehicles, and dispatchable loads should be utilized to maximize the consumption of the renewable energy and minimize the user's electricity cost. The source-grid-load level can smooth the tie-line power fluctuation through dispatching of the power grid and diesel generators. Furthermore, the study presents a modified MOEA/D algorithm to solve the hierarchical scheduling problem. In the proposed algorithm, a modified Tchebycheff decomposition method is introduced to obtain uniformly distributed solutions. In addition, initialization and replacement strategies are introduced to enhance the convergence and diversity. A wind-photovoltaic-diesel-storage hybrid power system is considered to verify the performance of the proposed dispatching strategy and the modified algorithm. The obtained results are compared with other dispatching approaches, and the comparisons confirm the effectiveness and scientificity of the proposed strategy and algorithm.

This paper investigates active damping of LCL filter resonance in grid-connected inverters with only inverter current feedback control, since it only needs to sample one current to realize both current control and inverter protection. The traditional single-loop inverter current control (SLICC) can damp the LCL filter resonance actively. However, if the control delay is considered in digital control, the system stability will depend on the ratio of the LCL resonance frequency to the sampling frequency , and the valid damping region is only up to . Considering that the design region of the LCL resonance frequency is up to , the system can easily become unstable due to the LCL resonance frequency shifting. Thus, this paper proposes an improved active damping method based on SLICC, including the asymmetric regular sampling method and delay compensation method. The improved sampling method minimizes the control delay without introducing a switching ripple, and the delay compensation method further compensates for the delay effect. With a proper parameter design, the upper limit of the valid damping region is extended up to , which can cover all the possible resonance frequencies, and it has inherent robustness against grid-impedance variation. Finally, a few simulations in MATLAB/SIMULINK and experiments based on a 6 kW prototype are performed to verify the theoretical analysis.