A multi-agent-based consensus algorithm for distributed coordinated control of distributed generators in the energy internet," IEEE Trans. Smart Grid, 2015.

This paper investigates the issue of accurate reactive, harmonic and imbalance power sharing in a microgrid. Harmonic and imbalance droop controllers are developed to proportionally share the harmonic power and the imbalance power among distributed generation (DG) units and improve the voltage quality at the point of common coupling (PCC). Further, a distributed consensus protocol is developed to adaptively regulate the virtual impedance at fundamental frequency and selected harmonic frequencies. Additionally, a dynamic consensus based method is adopted to restore the voltage to their average voltage. With the proposed methods, the microgrid system reliability and flexibility can be enhanced and the knowledge of the line impedance is not required. And the reactive, harmonic and imbalance power can be proportionally shared among the DG units. Moreover, the quality of the voltage at PCC can be greatly improved. Simulation and experimental results are presented to demonstrate the proposed method.Index Terms-microgrid, adaptive virtual impedance, reactive power sharing, harmonic power sharing, imbalance power sharing, distributed control, consensus protocol. NOMENCLATURE ω DGReference angular frequency of the DG unit ω *The nominal angular frequency of the DG unit E DG The reference voltage magnitude of the DG unit E * The nominal voltage magnitude of the DG unit m n Droop coefficients P Q Measured active and reactive power after low-pass filtering X DGf,i The reactance of DG equivalent positive sequence impedances Q Rated,i The rated reactive powers of DG units E DGh,i Reference harmonic voltage magnitudes of the DG units E DGI,i Reference imbalance voltage magnitudes of the DG units Q Har,i Harmonic power of the i th DG unit Q Imb,i Imbalance power of the i th DG unit n h,i Coefficient of the harmonic droop controller m I,i Coefficient of the imbalance droop controller

A distributed nonlinear controller is presented to achieve both accurate current-sharing and voltage regulation simultaneously in dc microgrids considering different line impedances' effects among converters. Then, an improved eventtriggered principle for the controller is introduced through combining the state-dependent tolerance with a nonnegative offset. In order to design the event-triggered principle and guarantee the global stability, a generalized dc microgrid model is proposed and proven to be positive definite, based on which Lyapunov-based approach is applied. Furthermore, considering the effects from constant power loads, the damping performance of proposed controller is further improved and compared with the traditional V-I droop controller. The proposed event-triggeredbased communication strategy can considerably reduce the communication traffic and significantly relax the requirement for precise real-time information transmission, without sacrificing system performance. Experimental results obtained from a dc microgrid setup show the robustness of the new proposal under normal, communication failure and communication delay operation conditions. Finally, communication traffic under different communication strategies are compared, showing a drastic traffic reduction when using the proposed approach.

Abstract-DC distribution is now becoming the major trend of future mobile power systems, such as more-electric aircrafts and ships. As DC distribution has different nature to conventional AC system, new design of well-structured control and management methods will be mandatory. In this paper, shipboard power system (SPS) with DC distribution and energy storage system (ESS) is picked as study case. To meet the requirement of control and management of such a large-scale mobile power system, a hierarchical control design is proposed in this paper. In order to fully exploit the benefit of ESS, as well as to overcome the limitation in controllability, a novel inverse-droop control method is proposed, in which the power sharing is according to the source characteristic, instead of their power rating. A frequency-division method is also proposed as an extension to the inverse-droop method for enabling hybrid energy storage system (HESS) and its autonomous operation. On the basis of the proposed methods, the control methods for management and voltage restoration levels are also proposed to establish a comprehensive control solution. Real-time simulations are carried out to validate the performance of proposed control design under different operating conditions. When compared to more conventional droop based approaches, the new proposal show enhancement in efficiency.Index Terms-Shipboard power system, DC distribution, energy storage, hierarchical control, more-electric ship, islanded microgrid.

In recent years, Cyber-Physical Systems (CPSs) have attracted intense attention due to their potential applications in many areas. However, the strong reliance on communication networks makes CPSs vulnerable to intentional cyber-attacks. Therefore, a great number of attack detection methods have been proposed to enforce security of CPSs. In this paper, various false data injection attack detection methods presented for CPSs are investigated and reviewed. According to the knowledge of control information, the controllers of CPSs are categorized as centralized and distributed controllers. Existing centralized attack detection approaches are discussed in terms of (i) linear time-invariant systems, (ii) actuator and sensor attacks, (iii) nonlinear systems and (iv) systems with noise. Furthermore, the development of distributed attack detection is reviewed according to different decoupling methods. Some challenges and future research directions in the context of attack detection approaches are provided.