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Low-voltage distribution lines lack efficient monitoring. With the massive proliferation of distributed energy resource supply, it is necessary to establish an effective monitoring system for low-voltage distribution lines to ensure the electrical safety and continuity of power supply services. This paper proposes monitoring system for low-voltage distribution lines based on the Internet of things (IoT) technology. An IoT based monitoring system contains a large number of low-voltage monitoring terminals, different manufacturers, and different types of terminal equipment to solve the interconnection problem of information interaction. This paper first analyzes the terminal functional communication requirements based on IEC 61850 standards. Further, the information models required by the electrical volume collection and non-electric quantity collection functions are studied. The information modeling for different types of monitoring terminal equipment is presented and thus provide the configuration suggestions. The monitoring terminal based on the information model developed in this paper is applied in a university campus to realize the monitoring of low-voltage lines and distributed power supply. [ABSTRACT FROM AUTHOR]

One of the main objectives of the Energy Management System (EMS) is to achieve a very high level of flexibility, stability, and the system must be able to adapt to most changes in the distribution network. This paper proposes a multi-agent system-based microgrid energy management to balance the energy supply and demand by feasibly integrating the energy storage system and demand response. An overall power management strategy is necessary to manage power flows among all interconnected elements of the microgrid. The principal contribution of this paper is an energy management system based on intelligent agents; each agent uses the microgrid data to manage the power flow in the microgrid. The interaction between agents proposed is simulated using JADE (Java Agent Development Environment) and the microgrid model is simulated using MATLAB/Simulink, both platforms are connected through the MACSimJX middleware for a dynamic simulation. [ABSTRACT FROM AUTHOR]

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This paper focuses on designing a simple yet efficient H∞ controller for regulating the voltage/frequency, output current, and active/reactive power-sharing in a microgrid (MG). The purpose of designing the robust H∞ controller is to regulate the frequency and voltage in face of the uncertainties in the microgrid and load variation. The studied DC MG test bed includes an SMPS (switching-mode power supply) and DC-DC converter, necessary sensor and data acquisition systems. The proposed control scheme is simulated using MATLAB/Simulink and is then verified in real-time using LabVIEW. The control scheme is developed in the LabVIEW software's block diagram panel of the virtual instrumentation interface. From both simulation and LabVIEW implementation, load sharing among the DGs, and voltage and frequency regulation at the nominal values are achieved by employing the proposed H∞ controller. The robustness of the proposed controller is evaluated by comparing it with a robust observer-based controller (Zarei A, Mousavi Y, Mosalanezhad R, Atazadegan MH. Robust voltage control in inverter-interfaced microgrids under plug-and-play functionalities. IEEE Syst J 2020;14:2813–24) under balanced, unbalanced, and non-linear loads. The comparison results envisage that the proposed controller provides improved voltage/frequency regulation and power-sharing during disturbances including the addition of non-linear load to the MG system. [ABSTRACT FROM AUTHOR]

The islanding detection is a major problem for both AC and DC Microgrids. Failure to do so may result in problems such as system instability, increased non-detection zone, out-of-phase reclosing, personnel safety, and power quality deterioration. To address this issue, this paper presents a reliable island identification method for DC Microgrids that employs a Cumulative Sum of Rate of change of Voltage (CSROCOV) to reduce the non-recognition region. The proposed islanding protection scheme employs point of common coupling (PCC) transient signal to detect islands events. The voltage, power, and current sampling are accumulated from the PCC of the distributed generation terminals. The proposed scheme detects islanding in three test cases with varying power mismatching conditions, while non-islanding events are classified as capacitor switching and faults. The system is modelled and simulated in the MATLAB/Simulink environment, then islanding conditions are applied by turning off the main circuit breaker. Simulation results are presented to verify the methodology under different test cases. The robustness of the proposed scheme is also validated against measurement noise. [ABSTRACT FROM AUTHOR]

Copyright of Automatisierungstechnik is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a coordinated power-sharing strategy for interconnected DC-microgrid (DC-MG) is proposed. The DC-MG consists of two subgrids with an interlinking bidirectional DC/DC converter (IBDDC). Each subgrid has a secondary-1 controller based on a state of charge (SoC) balancing based droop control strategy of the battery unit (BU). The proposed droop strategy regulates the DC bus voltage according to the SoC of BU. With the SoC balancing based droop method, BU with higher SoC supplies more power to the microgrid (MG) as compared to low SoC BU. The SoC information of batteries in all subgrids is communicated through low bandwidth communication (LBC). In case of failure of LBC, a secondary-2 controller is implemented for the battery controller to regulate the DC bus voltage considering the SoC of BU. Secondary-2 does not depend on the communication line. Considering the levels of DC bus voltages, a secondary power regulating controller is introduced for IBDDC. Further, a coordinated power control strategy is proposed for distributed generation to avoid overcharging of batteries. The whole system operates in a distributed way without a central controller. The proposed strategy has been verified in MATLAB/Simulink. [ABSTRACT FROM AUTHOR]

Demand response (DR), an integral part of the smart grid, has great potential in handling the challenges of the existing power grid. The potential of different DR programs in the energy management of residential consumers (RCs) and the integration of distributed energy resources (DERs) is an important research topic. A novel distributed approach for energy management of RCs considering the competitive interactions among them is presented in this paper. The impact of participation of RC's in price-based (PB) and incentive-based (IB) DR programs is investigated using game theory. For this, an energy management optimization problem (EMOP) is formulated to minimize electricity cost. The utility company employs electricity price as a linear function of aggregated load in the PB DR program and an incentive rate in the IBDR program. RCs are categorized into active and passive users. Active users are further distinguished based on the ownership of energy storage devices (SD) and dispatchable generation units (DGU). EMOP is modeled using a non-cooperative game, and the distributed proximal decomposition method is used to obtain the Nash equilibrium of the game. The results of the proposed approach are analyzed using different case studies. The performance of the proposed approach is evaluated in terms of aggregated cost and system load profile. It has been observed that participation in PB and IBDR program benefits both the utility and the consumers. [ABSTRACT FROM AUTHOR]

The content of this paper aims to assist in the development and implementation of microgrids by addressing the challenges and possible solutions for their protection systems. Therefore, an overview of some protection methods available in the literature that can be implemented to ensure a safe and reliable microgrid operation is presented, including the most common protection devices and earthing schemes that can be adopted in low voltage distribution systems. In addition, this paper also presents a brief fault analysis of internal faults at three different locations in an industrial microgrid with centralized and decentralized deployment of energy sources, as well as a short-circuit analysis of symmetric and asymmetric faults at these faulty locations. An approximate method based on the calculation of the equivalent impedance seen from the fault location is used to determine the fault currents. This study is made to observe how microgrids with different configurations perform in the event of internal faults. It is demonstrated in this work that setting a specific protection strategy to allow the microgrid to operate effectively during both operation modes can be problematic and expensive in most situations. With this in mind, additional effort is necessary to engineer and implement new protection approaches that can overcome the limitations of protection systems in future microgrids. [ABSTRACT FROM AUTHOR]

Generation of renewable energy sources and their interfacing to the main system has turn out to be most fascinating challenge. Renewable energy generation requires stable and reliable incorporation of energy to the low or medium voltage networks. This paper presents the microgrid modeling as an alternative and feasible power supply for Institute of Technology, Hawassa University, Ethiopia. This microgrid consists of a 60 kW photo voltaic (PV) and a 20 kW wind turbine (WT) system; that is linked to the electrical distribution system of the campus by a 3-phase pulse width modulation scheme based voltage source inverters (VSI) and supplying power to the university buildings. The main challenge in this work is related to the interconnection of microgrid with utility grid, using 3-phase VSI controller. The PV and WT of the microgrid are controlled in active and reactive power (PQ) control mode during grid connected operation and in voltage/frequency (V/F) control mode, when the microgrid is switched to the stand-alone operation. To demonstrate the feasibility of proposed microgrid model, MATLAB/Simulink software has been employed. The performance of fully functioning microgrid is analyzed and simulated for a number of operating conditions. Simulation results supported the usefulness of developed microgrid in both mode of operation. [ABSTRACT FROM AUTHOR]

The energy management system is established in the microgrid system for optimally integrating the Distributed Energy Resources (DERs) and generating the power distribution grids. At last, diverse mechanisms have been highly concentrated on cost reduction and at the same time, both the technical indices and economic factors are considered. Thus, this research work suggests a new heuristic algorithm termed Modified Sandpiper optimization algorithm (M-SOA) for optimal integration of DER-like Photo Voltaic (PV), wind turbines, and Energy Storage Systems (ESS) into microgrids. Here, the techno-economical optimization with ISOA is designed for determining the optimal capacity of PV, Wind Turbine, and ESS via the multi-objective function concerning measures like network power losses, voltage fluctuations, Electricity Supply Costs, initial cost, operation cost, fuel cost, and demand side management. Finally, the optimal energy management is done on distributed energy resources, and this developed model experiments on the IEEE-33 bus network. Throughout the result analysis, the developed M-SOA obtains 3.84 %, 0.98 %, 5.72 %, and 4.63 % better performance with less latency than the AGTO, BOA, WOA, and SOA. Finally, the result evaluation is done for minimizing the Electricity Supply Costs, initial cost, operation cost, and fuel cost and maximize energy efficiency. [ABSTRACT FROM AUTHOR]