Journal ArticleDOI
Distribution Voltage Control for DC Microgrids Using Fuzzy Control and Gain-Scheduling Technique
TLDR
In this paper, a low-voltage bipolar-type dc microgrid with two energy storage units and a dc/dc converter was proposed to achieve both power sharing and energy management.Abstract:
Installation of many distributed generations (DGs) could be detrimental to the power quality of utility grids. Microgrids facilitate effortless installation of DGs in conventional power systems. In recent years, dc microgrids have gained popularity because dc output sources such as photovoltaic systems, fuel cells, and batteries can be interconnected without ac/dc conversion, which contributes to total system efficiency. Moreover, high-quality power can be supplied continuously when voltage sags or blackouts occur in utility grids. We had already proposed a “low-voltage bipolar-type dc microgrid” and described its configuration, operation, and control scheme, through experiments. In the experiments, we used one energy storage unit with a dc/dc converter to maintain the dc-bus voltage under intentional islanding operation. However, dc microgrids should have two or more energy storage units for system redundancy. Therefore, we modified the system by adding another energy storage unit to our experimental system. Several kinds of droop controls have been proposed for parallel operations, some of which were applied for ac or dc microgrids. If a gain-scheduling control scheme is adopted to share the storage unit outputs, the storage energy would become unbalanced. This paper therefore presents a new voltage control that combines fuzzy control with gain-scheduling techniques to accomplish both power sharing and energy management. The experimental results show that the dc distribution voltages were within 340 V ± 5%, and the ratios of the stored energy were approximately equal, which implies that dc voltage regulation and stored energy balancing control can be realized simultaneously.read more
Citations
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Journal ArticleDOI
DC Microgrids—Part I: A Review of Control Strategies and Stabilization Techniques
TL;DR: In this paper, a review of control strategies, stability analysis, and stabilization techniques for dc microgrids is presented, where overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level.
Journal ArticleDOI
DC Microgrids—Part II: A Review of Power Architectures, Applications, and Standardization Issues
TL;DR: In this article, an overview of the state of the art in dc microgrid protection and grounding is provided, which discusses both design of practical protective devices and their integration into overall protection systems.
Journal ArticleDOI
An Improved Droop Control Method for DC Microgrids Based on Low Bandwidth Communication With DC Bus Voltage Restoration and Enhanced Current Sharing Accuracy
TL;DR: In this article, a lowbandwidth communication (LBC)-based improved droop control method is proposed to improve the performance of the dc microgrid operation, which does not require a centralized secondary controller.
Journal ArticleDOI
Distributed Cooperative Control of DC Microgrids
TL;DR: In this paper, a cooperative control paradigm is used to establish a distributed secondary/primary control framework for dc microgrids, where the conventional secondary control, that adjusts the voltage set point for the local droop mechanism, is replaced by a voltage regulator and a current regulator.
Journal ArticleDOI
Overview of Power Management Strategies of Hybrid AC/DC Microgrid
Farzam Nejabatkhah,Yun Wei Li +1 more
TL;DR: This paper presents an overview of power management strategies for a hybrid ac/dc microgrid system, which includes different system structures, different operation modes, a thorough study of various power management and control schemes in both steady state and transient conditions, and examples of powermanagement and control strategies.
References
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Journal ArticleDOI
Dynamic Behavior and Stabilization of DC Microgrids With Instantaneous Constant-Power Loads
TL;DR: In this article, stability issues in dc microgrids with instantaneous constant-power loads (CPLs) are explored and mitigation strategies such as load shedding, adding resistive loads, filters, or energy storage directly connected to the main bus, and control methods are investigated.
Proceedings Article
DC microgrid based distribution power generation system
TL;DR: In this article, an autonomous control method for a DC microgrid system having distribution power generators is described, which brings high reliability, high-flexibility and maintenance-free operation to the system.
Journal ArticleDOI
Impact of DC Line Voltage Drops on Power Flow of MTDC Using Droop Control
TL;DR: In this paper, an analytical expression for estimating the distribution of balancing power which accounts for dc line voltage drops is derived for a five-terminal VSC-HVDC system.
Journal ArticleDOI
Quantitative Evaluation of DC Microgrids Availability: Effects of System Architecture and Converter Topology Design Choices
TL;DR: In this paper, the authors present a quantitative method to evaluate dc microgrids availability by identifying and calculating minimum cut sets occurrence probability for different microgrid architectures and converter topologies, which provides planners with an essential tool to evaluate downtime costs and decide technology deployments based on quantitative risk assessments by allowing to compare the effect that converter topology and microgrid architecture choices have on availability.
Journal ArticleDOI
A Current-Control Strategy for Voltage-Source Inverters in Microgrids Based on $H^{\infty }$ and Repetitive Control
T Hornik,Qing-Chang Zhong +1 more
TL;DR: In this paper, a current controller for voltage-source inverters in microgrids is proposed to inject a clean sinusoidal current to the grid, even in the presence of nonlinear/unbalanced loads and/or gridvoltage distortions.