1,679 research outputs found
A Comprehensive Review of the State-of-the-Art of Secondary Control Strategies for Microgrids
The proliferation of distributed energy resources in distribution systems has given rise to a new concept known as Microgrids (MGs). The effective control of MGs is a crucial aspect that needs to be prioritized before undertaking any implementation procedure. This article provides a comprehensive overview of hierarchical control methods that ensure efficient and robust control for MGs. Specifically, it focuses on the secondary controller approaches (centralized, distributed, and decentralized control) and examines their primary strengths and weaknesses. The techniques are thoroughly discussed, deliberated, and compared to facilitate a better understanding. According to functionality, the hierarchical-based control scheme is allocated into three levels: primary, secondary, and tertiary. For secondary control level, the MG communication structures permit the usage of various control methods that provided the significance of the secondary controller for consistent and reliable MG performance and the deficiency of an inclusive recommendation for scholars. Also, it gives a review of the literature on present important matters related to MG secondary control approaches in relation to the challenges of communication systems. The problem of the secondary level control is deliberated with an emphasis on challenges like delays. Further, at the secondary layer, the distributed control techniques for reducing communication system utilization and then reducing communication system delays are conferred. Furthermore, the benefits and limitations of various control structures, such as centralized, decentralized, and distributed are also discusses in this study. Later a comparative analysis of entire control approaches, the best methods of control according to the author's perspective are also discussed
Distributed Control Strategies for Microgrids: An Overview
There is an increasing interest and research effort focused on the analysis, design and implementation of distributed control systems for AC, DC and hybrid AC/DC microgrids. It is claimed that distributed controllers have several advantages over centralised control schemes, e.g., improved reliability, flexibility, controllability, black start operation, robustness to failure in the communication links, etc. In this work, an overview of the state-of-the-art of distributed cooperative control systems for isolated microgrids is presented. Protocols for cooperative control such as linear consensus, heterogeneous consensus and finite-time consensus are discussed and reviewed in this paper. Distributed cooperative algorithms for primary and secondary control systems, including (among others issues) virtual impedance, synthetic inertia, droop-free control, stability analysis, imbalance sharing, total harmonic distortion regulation, are also reviewed and discussed in this survey. Tertiary control systems, e.g., for economic dispatch of electric energy, based on cooperative control approaches, are also addressed in this work. This review also highlights existing issues, research challenges and future trends in distributed cooperative control of microgrids and their future applications
Secondary Frequency and Voltage Control of Islanded Microgrids via Distributed Averaging
In this work we present new distributed controllers for secondary frequency
and voltage control in islanded microgrids. Inspired by techniques from
cooperative control, the proposed controllers use localized information and
nearest-neighbor communication to collectively perform secondary control
actions. The frequency controller rapidly regulates the microgrid frequency to
its nominal value while maintaining active power sharing among the distributed
generators. Tuning of the voltage controller provides a simple and intuitive
trade-off between the conflicting goals of voltage regulation and reactive
power sharing. Our designs require no knowledge of the microgrid topology,
impedances or loads. The distributed architecture allows for flexibility and
redundancy, and eliminates the need for a central microgrid controller. We
provide a voltage stability analysis and present extensive experimental results
validating our designs, verifying robust performance under communication
failure and during plug-and-play operation.Comment: Accepted for publication in IEEE Transactions on Industrial
Electronic
Secondary Control Strategies for Frequency Restoration in Islanded Microgrids with Consideration of Communication Delays
One of the well-known methods to share active and reactive power in microgrids (MGs) is droop control. A disadvantage of this method is that in steady state the frequency of the MG deviates from the nominal value and has to be restored using a secondary control system (SCS). The signal obtained at the output of the SCS is transmitted using a communication channel to the generation sources in the MG, correcting the frequency. However, communication channels are prone to time delays, which should be considered in the design of the SCS; otherwise, the operation of the MG could be compromised. In this paper, two new SCSs control schemes are discussed to deal with this issue: 1) a model predictive controller (MPC); and 2) a Smith predictor-based controller. The performance of both control methodologies are compared with that obtained using a conventional proportional integral-based SCS using simulation work. Stability analysis based on small signal models and participation factors is also realized. It is concluded that in terms of robustness, the MPC has better performance.FONDECYT
1140775
Advanced Center for Electrical and Electronic Engineering
Basal Project
FB0008
Fondequip
EQM13005
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