The significant benefits associated with microgrids have led to vast efforts to expand their penetration in electric power systems. Although their deployment is rapidly growing, there are still many challenges to efficiently design, control, and operate microgrids when connected to the grid, and also when in islanded mode, where extensive research activities are underway to tackle these issues. It is necessary to have an across-the-board view of the microgrid integration in power systems. This paper presents a review of issues concerning microgrids and provides an account of research in areas related to microgrids, including distributed generation, microgrid value propositions, applications of power electronics, economic issues, microgrid operation and control, microgrid clusters, and protection and communications issues.

State of the Art in Research on Microgrids: A Review

The black start capability is vital for microgrids, which can potentially improve the reliability of the power grid. This paper proposes a black start strategy for microgrids based on a parallel restoration strategy. Considering the characteristics of distributed generations (DGs), an evaluation model, which is used to assess the black start capability of DGs, is established by adopting the variation coefficient method. Thus, the DGs with good black start capability, which are selected by a diversity sequence method, are restored first in parallel under the constraints of DGs and network. During the selection process of recovery paths, line weight and node importance degree are proposed under the consideration of the node topological importance and the load importance as well as the backbone network restoration time. Therefore, the whole optimization of the reconstructed network is realized. Finally, the simulation results verify the feasibility and effectiveness of the strategy.

A Parallel Restoration for Black Start of Microgrids Considering Characteristics of Distributed Generations

Survey of multi-agent systems for microgrid control

Multi-agent systems applied for energy systems integration: State-of-the-art applications and trends in microgrids

A system for intrusion detection in a field area network where data is transmitted via packets, includes a processor for analyzing the packets to ascertain whether the packets conform to a sets of rules indicating an intrusion, and a database for storing an alert indicating an intrusion if the packets conform to at least one rule in the sets. The sets of rules are for field network layer data, internet protocol traffic data and field area application traffic data. A method for detecting intrusion in a field area network where data is transmitted via packets, including analyzing the packets to ascertain whether the packets conform to the sets of rules, and storing an alert indicating an intrusion if the packets conform to at least one rule in the sets of rules.

Method and system for packet acquisition, analysis and intrusion detection in field area networks

Microgrids have become a hot topic driven by the dual pressures of environmental protection concerns and the energy crisis. In this paper, a challenge for the distributed control of a modern electric grid incorporating clusters of residential microgrids is elaborated and a hierarchical multi-agent system (MAS) is proposed as a solution. The issues of how to realize the hierarchical MAS and how to improve coordination and control strategies are discussed. Based on MATLAB and ZEUS platforms, bilateral switching between grid-connected mode and island mode is performed under control of the proposed MAS to enhance and support its effectiveness.

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Hierarchical MAS Based Control Strategy for Microgrid

Microgrid is a controllable unit integrated by distributed energy, load, energy storage and control devices. The operation and control of microgrid is the key to ensure the safety and stability of the power grid. In this paper, we design a microgrid monitor and control system based on IP and Multi-Agent, established by MATLAB and ZEUS platform. The bilateral switching between grid-connected mode and island mode is implemented by simulation. The results indicate the feasibility of multi-agent control system for microgrid control, operation and management.

Control system simulation of microgrid based on IP and Multi-Agent

Transformation thermodynamics as a major extension of transformation optics has recently received considerable attention. In this paper, we present two-dimensional (2D) and three-dimensional (3D) diamond-shaped transient thermal cloaks with non-singular homogeneous material parameters. The absence of singularity in the parameters results from the fact that the linear coordinate transformation is performed by expanding a line segment rather than a point into a region, while the mechanism behind the homogeneity is the homogeneous stretching and compression along orthogonal directions during the transformation. Although the derived parameters remain anisotropic, we further show that this can be circumvented by considering a layered structure composed of only four types of isotropic materials based on the effective medium theory. Numerical simulation results confirm the good performance of the proposed cloaks.

Design of diamond-shaped transient thermal cloaks with homogeneous isotropic materials

The two-dimensional and three-dimensional acoustic cloaks composed of homogeneous and nonsingular materials are designed by choosing appropriate spatial transformation. The mass density tensor and bulk modulus of the acoustic cloaks with diamond shape are derived, and extended to an acoustic carpet cloak. Performance of the acoustic cloaks is confirmed by full-wave simulation. The work represents an important progress towards the practical realization of the metamaterial-assisted acoustic cloak and expands the application of the coordinate transformation method.

Homogeneous Material Constructed Acoustic Cloak Based on Coordinate Transformation

Based on coordinate transformation method, the two-dimensional and three-dimensional acoustic concentrators with diamond shape composed of nonsingular homogeneous materials are designed in this paper. The mass density tensor and bulk modulus of the acoustic concentrators are derived. Performance of the concentrators is confirmed by full-wave simulation. The work represents an important progress towards the practical realization of the metamaterial-assisted acoustic concentrator and expands the application of the coordinate transformation method.

Tinghua Li

Papers

Hierarchical MAS Based Control Strategy for Microgrid

Control system simulation of microgrid based on IP and Multi-Agent

Design of diamond-shaped transient thermal cloaks with homogeneous isotropic materials

Homogeneous Material Constructed Acoustic Cloak Based on Coordinate Transformation

Diamond-shaped acoustic concentrator with homogeneous material parameters