A review on control and fault-tolerant control systems of AC/DC microgrids (original) (raw)
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MAS-based Adaptive Control Scheme for AC Microgrids with increased fault-tolerance needs
IET Renewable Power Generation
This paper presents a fault-tolerant secondary and adaptive primary microgrid control scheme using a hybrid multiagent system (MAS), capable of operating either in a semi-centralised or distributed manner. The proposed scheme includes a droop-based primary level that considers the microgrid energy reserves in production and storage. The secondary level is responsible for: a) the microgrid units' coordination, b) voltage and frequency restoration and c) calculation of the droop/ reversed-droop coefficients. The suggested architecture is arranged upon a group of dedicated asset agents that collect local measurements, take decisions independently and, collaborate in order to achieve more complex control objectives. Additionally, a supervising agent is added to fulfill secondary level objectives. The hybrid MAS can operate either with or without the supervising agent operational, manifesting fast redistribution of the supervising agent tasks. The proposed hybrid scheme is tested in simulation upon two separate physical microgrids using three scenarios. Additionally, a comparison with conventional control methodologies is performed in order to illustrate further the operation of a hybrid approach. Overall, results show that the proposed control framework exhibits unique characteristics regarding reconfigurability and fault-tolerance, while power quality and improved load sharing are ensured even in case of critical component failure. 1 Introduction Microgrids have been gaining increasing attention over the past years. They represent prosperous solutions to both distributed energy resources (DERs) and to stand-alone, isolated power systems that may be used for special applications such as telecommunication stations and remote area research bases. Microgrid DERs are normally converter interfaced in the sense that microgrids become structures of parallel converters, posing challenges to control systems design, especially in case of islanded operation [1]. As a rapidly evolving field of research, highly diverse control system solutions have been proposed by both academia and industry. Depending on the control design and operating time frame of the systems implementing the microgrid control core objectives, a plethora of centralised, decentralised, distributed and hierarchical control approaches have been proposed [2]. Despite the different design implementations, it can be observed that microgrid control systems follow a certain hierarchy. This hierarchy is most frequently divided into three layers, which are generally described as follows: primary level undertakes load
A Methodology of Sensor Fault-Tolerant Control on a Hierarchical Control for Hybrid Microgrids
IEEE Access, 2023
This study develops a new Sensor Fault-Tolerant methodology for two-level Centralized Hierarchical Control of isolated microgrids based on a modified Kalman filter algorithm. The main objective is to increase the reliability and safety margins of isolated smart microgrids in the presence of different sensor faults on the secondary control. Consequently, Sensor Fault-Tolerant control reduces the costs because costly redundant hardware is not required. Because of its low computing effort, speed, ease of implementation, and tuning, this method can be used in more complex control configurations, multiple sensor faults, and different hierarchical control levels. The designed Sensor Fault-Tolerant Hierarchical Control System was initially proposed for a grid-forming topology of single-phase BESSs systems connected in cascade to the microgrid. The implemented fault tolerance methodology can maintain control objectives with sensor faults. Consequently, the MG's voltage at the time of the fault does not exceed 5%, and the voltage unbalance at the common coupling point or on the critical bus is compensated to a quality reference value of less than 2%. The performance of the proposed algorithm is tested using the MATLAB/Simulink simulation platform.
Modeling, Control & Fault Management of Microgrids
Smart Grid and Renewable Energy, 2013
In this paper, modeling and decentralize control principles of a MicroGrid (MG) whom equipped with three Distributed Generation (DG) systems (consist of: Solar Cell System (SCS), MicroTurbine System (MTS) and Wind Energy Conversion System (WECS)) is simulated. Three arrangement of load changing have investigated for the system. In first one the system doesn't have transfer of power between MG and grid. In other two arrangements system have transfer of power between MG and utility grid. Of course in third case transfer of power between DG resources is considerable. Case study system is equipped by energy storage devices (battery bank) for each DG's separately by means of increasing the MG reliability. For WECS and SCS, MPPT control and for MTS, voltage and frequency (V&F) controller has designed. The purpose of this paper is load respond in MG and storage process of surplus energy by consider of load changing. MATLAB/Simulink and its libraries (mainly the Sim Power Systems toolbox) were employed in order to develop a simulation platform suitable for identifying MG control requirements. This paper reported a control and operation of MG in network tension by applying a three phase fault.
Hierarchical Control of Ac Microgrids
2018
Microgrids are a group of localized electrical resources mainly using renewable resources as a main source of power, which can operate independently or in collaboration with utility grid. When connection of a microgrid is concerned, switching from an islanding to grid-connected mode is always a difficult task for a microgrid mainly due to transients and mismatching in synchronization. Hierarchical control structure of a microgrid eradicates this issue by separating the control structure in multiple levels. This thesis explains different levels of hierarchical control strategies, which constitute primary control, secondary and tertiary control. The primary control is based on droop control including output virtual impedance, secondary control performs restoration of voltage and frequency performed by primary and tertiary control maintain the power flow between the micro grid and external utility. In first step, this thesis covers the technical overview of traditional control methods ...
IET Renewable Power Generation, 2019
This paper presents a fault-tolerant secondary and adaptive primary microgrid control scheme using a hybrid multi-agent system, capable of operating based on either semi-centralised or distributed control modes. The proposed scheme includes a droop-based primary control level that operates by taking into consideration the microgrid energy reserves in both production and storage. Since the proposed scheme is designed for microgrids with AC-coupled units, the secondary level is responsible for: a) the coordination of the microgrid units operation, b) voltage and frequency restoration and c) calculation of the droop/ reversed-droop coefficients. The suggested architecture is arranged upon a group of dedicated asset agents and a supervising agent: each microgrid asset-such as PV, energy storage system, load bus-has a preassigned agent that is able to collect local measurements, take decisions independently and finally, collaborate with the rest of the agents in order to achieve more complex control objectives. The multi-agent system is easily scalable, thanks to its build-in "plug-and-play" capability. Further, it can operate in a flexible manner either with or without the supervising agent operational, owing to fast redistribution of the supervising agent tasks. In order to test the proposed hybrid scheme, two separate physical microgrids have been modelled and used on three simulation scenarios. The multi-agent system interacts with simulation models similar to real physical systems. Contingencies and fault scenarios of microgrids are examined. Additionally, a comparison with conventional control methodologies is performed in order to illustrate further the operation of a hybrid approach. Overall, results show that the proposed control framework exhibits unique characteristics regarding reconfigurability and fault-tolerance, while power quality and improved load sharing are ensured even in case of critical component failure.
Modeling, Control & Fault Management of Microgrids
In this paper, modeling and decentralize control principles of a MicroGrid (MG) whom equipped with three Distributed Generation (DG) systems (consist of: Solar Cell System (SCS), MicroTurbine System (MTS) and Wind Energy Conversion System (WECS)) is simulated. Three arrangement of load changing have investigated for the system. In first one the system doesn't have transfer of power between MG and grid. In other two arrangements system have transfer of power between MG and utility grid. Of course in third case transfer of power between DG resources is considerable. Case study system is equipped by energy storage devices (battery bank) for each DG's separately by means of increasing the MG reliability. For WECS and SCS, MPPT control and for MTS, voltage and frequency (V&F) controller has designed. The purpose of this paper is load respond in MG and storage process of surplus energy by consider of load changing. MATLAB/Simulink and its libraries (mainly the Sim Power Systems toolbox) were employed in order to develop a simulation platform suitable for identifying MG control requirements. This paper reported a control and operation of MG in network tension by applying a three phase fault.
Invariant Set-Based DC Microgrid Decentralized Actuator Fault-Tolerant Control
IEEE Access
Faults and system failure components are primarily two causes of unstable or deteriorating control performance of power system. In this study, we present a novel approach to the decentralized restoration of large DC microgrids using fault-tolerant control (FTC). The microgrid achieves decentralization by partitioning into several smaller grids. Each independent grid views the actions of the other grids as an external disturbance. The malfunction of the controller is represented in the input matrix as a normbounded uncertainty. The disturbance impact is diminished due to the proposed invariant-set approach. The proposed control can address simultaneous failures in actuators with random placement and degradation levels. In a passive FTC system, when the defect cannot be detected (or the fault may not have been clearly addressed), the proposed technique is utilized. After the fault has occurred, it can be viewed as an uncertainty in system dynamics. The controller that stabilizes the system is obtained by solving iteratively bilinear matrix inequalities as linear matrix inequalities. In addition, this study presents and discusses positive outcomes of applying this method to a system of six interconnected DC microgrids in the event of multiple fault types. The proposed control successfully stabilizes the severe case of simultaneous actuator faults. INDEX TERMS DC microgrid (MG), decentralized control, fault-tolerant control, invariant ellipsoid, robust tracker.
Decentralized Sensor Fault-Tolerant Control of DC Microgrids Using the Attracting Ellipsoid Method
Sensors
System stability deterioration in microgrids commonly occurs due to unpredictable faults and equipment malfunctions. Recently, robust control techniques have been used in microgrid systems to address these difficulties. In this paper, for DC-islanded microgrids that have sensors faults, a new passive fault-tolerant control strategy is developed. The suggested approach can be used to maintain system stability in the presence of flaws, such as faulty actuators and sensors, as well as component failures. The suggested control is effective when the fault is never recognized (or when the fault is not being precisely known, and some ambiguity in the fault may be interpreted as uncertainty in the system’s dynamics following the fault). The design is built around a derived sufficient condition in the context of linear matrix inequalities (LMIs) and the attractive ellipsoid technique. The ellipsoidal stabilization idea is to bring the state trajectories into a small region including the orig...
IEEE Access
The significant benefits of DC microgrids have instigated extensive efforts to be an alternative network as compared to conventional AC power networks. Although their deployment is ever-growing, multiple challenges still occurred for the protection of DC microgrids to efficiently design, control, and operate the system for the islanded mode and grid-tied mode. Therefore, there are extensive research activities underway to tackle these issues. The challenge arises from the sudden exponential increase in DC fault current, which must be extinguished in the absence of the naturally occurring zero crossings, potentially leading to sustained arcs. This paper presents cut-age and state-of-the-art issues concerning the fault management of DC microgrids. It provides an account of research in areas related to fault management of DC microgrids, including fault detection, location, identification, isolation, and reconfiguration. In each area, a comprehensive review has been carried out to identify the fault management of DC microgrids. Finally, future trends and challenges regarding fault management in DC-microgrids are also discussed.