This paper presents the latest comprehensive literature review of AC and DC microgrid (MG) systems in connection with distributed generation (DG) units using renewable energy sources (RESs), energy storage systems (ESS) and loads. A survey on the alternative DG units' configurations in the low voltage AC (LVAC) and DC (LVDC) distribution networks with several applications of microgrid systems in the viewpoint of the current and the future consumer equipments energy market is extensively discussed. Based on the economical, technical and environmental benefits of the renewable energy related DG units, a thorough comparison between the two types of microgrid systems is provided. The paper also investigates the feasibility, control and energy management strategies of the two microgrid systems relying on the most current research works. Finally, the generalized relay tripping currents are derived and the protection strategies in microgrid systems are addressed in detail. From this literature survey, it can be revealed that the AC and DC microgrid systems with multiconverter devices are intrinsically potential for the future energy systems to achieve reliability, efficiency and quality power supply.

AC-microgrids versus DC-microgrids with distributed energy resources: A review

Social Stratification in Science

Research in closed-loop supply chains (CLSCs) has grown rapidly over the last 10 years. The authors offer a critical review of influential CLSC research that takes a business economics perspective. Much of the research was inspired by practice-driven thoughtpieces, and this helped to keep research focused on relevant issues. However, CLSC research has several assumptions, such as perfect substitution between new and remanufactured products that risk becoming institutionalized. There is a strong need to carefully examine current industrial practice so that research remains focused on relevant problems. Deeper understanding of consumer perceptions of remanufactured products, product diffusion, and valuation of returned products are needed for the field to continue to add insights into developing sustainable economies.

Production and Operations Management

Links and impacts: the influence of public research on industrial R&D

How to write and publish a scientific paper

Though distributed generators (DGs) have significant economic and environmental benefits, increased penetration of DGs will impose significant technical barriers for the efficient and effective operation of bulk power systems. Increased fault current contribution and load flow changes are the major two impacts on utility systems, and these will affect existing protective relaying, especially overcurrent relays. To ensure safe and selective protection relay coordination, the impact of DGs should be taken into account when planning DG interconnection. This paper presents an introduction of DGs and an overview of the impacts of DGs on system protection relay coordination. Several protection issues are identified to study the requirements for protection in the presence of DGs are also discussed.

	 

	Key words: Distributed generator (DG), protection coordination, distribution network, overcurrent relay.

Impact of Distributed Generations on Power System Protection Performance

Automated Fault Location in a Power System with Distributed Generations Using Radial Basis Function Neural Networks

The increase in interconnection of distributed generators (DGs) to distribution network will greatly affect the configuration and operation mode of the power system, especially with respect to the protection scheme. However, when DG units are connected to a distribution network, the system is no longer radial, which causes a loss of coordination among network protection devices and will have unfavorable impacts on the traditional fault location methods. In this paper a new automated fault location method by using radial basis function neural network (RBFNN) for a distribution network with DGs has presented. The suggested approach is able to determine the accurate type and location of faults using RBF neural network. Several case studies have been made to verify the accuracy of the proposed method for fault diagnosis in a distribution system with DGs using a MATLAB based developed software and DIgSILENT Power Factory 14.0.523. Results showed that the proposed method can accurately determine the location of faults in a distribution system with several DG units.

Determining exact fault location in a distribution network in presence of DGs using RBF neural networks

With high penetration of distributed generations (DGs), power distribution system is regarded as a multisource system in which fault location scheme must be direction sensitive. This paper presents an automated fault location method using radial basis function neural network (RBFNN) for a distribution system with DG units. In the proposed method, the fault type is first determined by normalizing the fault currents of the main source and then fault location is predicted by using RBFNN. Several case studies have been considered to verify the accuracy of the RBFNN. A comparison is also made between the RBFNN and the conventional multilayer perceptron neural network for locating faults in a power distribution system with DGs. The test results showed that the RBFNN can accurately determine the location of faults in a distribution system with several DG units.

Performance comparison of MLP and RBF neural networks for fault location in distribution networks with DGs

This paper presents an overview of solutions proposed in the literature for the overcurrent relay coordination problem in the presence of distributed generators (DGs). Furthermore, several protection issues are identified to study the requirements for protection in the presence of DGs, and possible innovative solutions for resolving the operational conflicts between distribution networks and DGs are also discussed. Streszczenie. W artykule zaprezentowano przegląd metod zabezpieczen przed przekroczeniem prądow dopuszczalnych w sieci z rozproszonymi generatorami. Szereg rozwiązan przeanalizowano pod kątem mozliwych konfliktow miedzy siecią dystrybucyjną i generatorami. (Przegląd zabezpieczen prądowych w sieci z generatorami rozproszonymi)

Marjan Mohammadjafari

Papers

Impact of Distributed Generations on Power System Protection Performance

Automated Fault Location in a Power System with Distributed Generations Using Radial Basis Function Neural Networks

Determining exact fault location in a distribution network in presence of DGs using RBF neural networks

Performance comparison of MLP and RBF neural networks for fault location in distribution networks with DGs

A Comprehensive review of protection coordination methods in power distribution systems in the presence of DG