DC Microgrid Research Articles

Novel hybrid of marine predator algorithm-Aquila optimizer for droop control in DC microgrid

This study presents a hybrid method, namely the marine predator algorithm (MPA) and Aquila optimizer (AO). The proposed algorithm is named MAO. AO duplicated the existence of the Aquila bird in nature while hunting for prey while MPA was inspired by predators in marine animal life. Although AO is widely accepted, it has several disadvantages. This causes various weaknesses such as a weak exploitation phase and slow growth of the convergence curve. Thus, certain exploitation and exploration in conventional AO can be studied to achieve the best balance. The MPA demonstrates the capacity to deliver optimal design and statistically efficient outcomes. The proposed method used AO as the main algorithm. To measure the performance of the proposed method, this study depicted a comparison using the AO, MPA, and whale optimization algorithm (WOA) methods. This paper was evaluated the performance of MAO on twenty-one CEC2017 benchmark functions test and droop control performance on direct current (DC) microgrid. From the simulation, MAO shows superior convergence ability. The proposed method and its application to droop control was successfully implemented and implied a promising performance.

Decentralized Adaptive Energy-Shaping for Integrated Voltage Regulation With Large-Signal Stability in DC Microgrids

Decentralized Adaptive Energy-Shaping for Integrated Voltage Regulation With Large-Signal Stability in DC Microgrids

High-power three-phase interleaved parallel NPC structure DC-DC converter modeling and simulation

Abstract In fields such as DC microgrids, renewable energy generation, and electric vehicle charging stations, three-phase NPC structure DC-DC converters play an irreplaceable role, constituting a significant part of modern power electronics technology. Mathematical models are established based on various operating modes of IGBT switching devices under PWM control, encompassing input voltage, output voltage, phase currents, average current, and duty cycle. Simulation models are constructed on the MATLAB platform to confirm the correctness of these mathematical models. Closed-loop control strategies are implemented using proportional-integral (PI) controllers. This control strategy serves to confirm the precision of the mathematical models.

An Adaptive Virtual Resistance Method Based on a Superimposed Frequency for Power Distribution in DC Microgrids

An Adaptive Virtual Resistance Method Based on a Superimposed Frequency for Power Distribution in DC Microgrids

Proportional‐integral‐differential‐inspired acceleration in distributed optimal control strategy for direct current microgrids

AbstractA PID‐inspired accelerated distributed optimal control algorithm is proposed for the economic dispatch problem of a multi‐bus DC microgrid, which contains both conventional generators (CGs) and renewable generators (RGs). Firstly, a constrained optimization problem with the aim of minimizing the power generation cost of the DC microgrid is established. To solve the optimization problem, an accelerated distributed optimal control algorithm in the discrete‐time domain is proposed. The convergence speed of the proposed algorithm is significantly improved compared to the existing distributed optimization algorithms without acceleration terms. More importantly, the communication cost is greatly reduced. The proposed algorithm is in a fully distributed manner, which means each controller only relies on the limited information from neighbouring controllers to achieve optimal cooperative control and bus voltage regulation across multiple buses. Finally, the effectiveness of the proposed algorithm is validated through numerical simulations.

Novel Grounding and Protection Strategy for DC Microgrid Restraining Fault Current

Novel Grounding and Protection Strategy for DC Microgrid Restraining Fault Current

Resilient Control of DC Microgrids Against FDI Attacks on Communication Links and Local Current Measurements

Resilient Control of DC Microgrids Against FDI Attacks on Communication Links and Local Current Measurements

A Novel Scalable Fault-Tolerant Control Design for DC Microgrids With Nonuniform Faults

A Novel Scalable Fault-Tolerant Control Design for DC Microgrids With Nonuniform Faults

Additional damping control for multi-terminal AC-DC hybrid system based on reachability analysis

Abstract The application proportion of multi-terminal AC-DC hybrid power distribution systems is constantly increasing. In order to describe the operation status and trajectory of the system and judge whether the system can maintain stable and safe operation, in this paper, the differential algebraic equation is firstly established by mathematical and physical methods for a typical multi-terminal AC-DC hybrid power distribution system. Then, the reachable set in the operation process is analyzed according to the reachability analysis calculation method to judge the stable operation status. An additional damping control method is proposed, which can effectively restrain the negative impedance characteristics of the DC micro-grid and improve the operation stability of the system. Finally, the improvement performance of the control method is verified by combining the reachability analysis results.

Scalable Fuzzy Control for Nonlinear DC Microgrids Under Plug-and-Play Operations

Scalable Fuzzy Control for Nonlinear DC Microgrids Under Plug-and-Play Operations

Distributed Event-Triggered Optimal Algorithm Designs for Economic Dispatching of DC Microgrid with Conventional and Renewable Generators: Actuator-Based Control and Optimization

Distributed Event-Triggered Optimal Algorithm Designs for Economic Dispatching of DC Microgrid with Conventional and Renewable Generators: Actuator-Based Control and Optimization

Queen honey bee migration (QHBM) optimization for droop control on DC microgrid under load variation

Transmission line impedance in DC microgrids can cause voltage dips and uneven current distribution, negatively impacting droop control and voltage stability. To address this, this study proposes an optimization approach using heuristic techniques to determine the optimal droop parameters. The optimizcv ation considers reference voltage constraints and virtual impedance at various load conditions, particularly resistive. The optimization problem is addressed using two techniques: queen honey bee migration (QHBM) and particle swarm optimization (PSO). Simulation results show that QHBM reaches an error of 0.8737 at the fourth iteration. The QHBM and PSO algorithms successfully optimized the performance of the DC microgrid under diverse loads, with QHBM converging in 5 iterations with an error of about 0.8737, and PSO in 40 iterations drawn error is 0.9 while keeping the current deviation less than 1.5 A and voltage error less than 0.5 V. The deviation of current control and virtual impedance values are verified through comprehensive simulations in MATLAB/Simulink.

Distributed predefined-time secondary control under directed networks for DC microgrids

DC microgrids (MGs) have gained significant attention due to their ability to complement renewable energy generation. In order to improve the operational stability of DC MGs, a predefined-time-based secondary controller is proposed to restore voltage drops caused by droop control and achieve current allocation among agents according to expected ratios. To conserve communication resources, the communication topology is established as a directed network. Each distributed generator (DG) receives voltage and current information from neighboring devices and uses its own current and voltage regulators to achieve control objectives. Compared to existing controllers, the convergence time upper bound of the proposed approach is independent of the initial value and can be directly adjusted as a parameter. The stability of the proposed control strategy is then verified using Lyapunov theory. Finally, hardware-in-loop test results are conducted to validate the performance of the control strategy, and its superiority is demonstrated through comparison with existing control methods.

Optimizing Distributed Generation in DC Microgrids: A Comprehensive Study

This thorough examination offers a critical analysis of the intricate relationship between Distributed Generation (DG) and DC microgrids. It provides a thorough analysis of basic ideas, sophisticated control techniques, technological developments, and useful applications in actual situations. In the framework of a paradigm shift towards decentralized energy solutions, this study investigates the efficacy of Direct Current (DC) microgrids in integrating and optimizing diverse distributed generation sources. The study conducts a critical analysis of the challenges and possibilities related to various distributed generation technologies and renewable energy systems. For scientists, engineers, and policymakers engaged in the challenging task of incorporating dispersed energy into current systems, it offers crucial perspectives. This review is an important tool that advances our knowledge of distributed generation in DC microgrids. It contributes significantly to the development of discussions on resilient and sustainable energy solutions. In addition to discussing the challenges associated with DG integration, this study highlights real-world examples that highlight the adaptability and efficiency of DC microgrid designs. Because it includes a thorough examination of power electronics, energy storage, and advanced control systems, this study is an invaluable resource for stakeholders hoping to take advantage of DC microgrids. Through the integration of analytical analysis and pragmatic application, this review provides insightful analysis and field assistance. The entire study contributes significantly to the advancement of distributed generation (DG) integration, which is necessary to establish a sustainable and resilient energy environment. It offers the fundamental knowledge required to accomplish successful integration. This review paper offers an in-depth analysis of DG integration in DC microgrids. This review is to provide a comprehensive overview of the dynamic landscape where distributed energy generation and DC microgrids interact, starting with the foundational ideas and moving on to a close examination of the difficulties, innovations in technology, and useful applications.

A new fault detection and relay coordination technique for low voltage DC microgrid

Integration of various distributed generation units in the DC distribution network creates an outsized impact on magnitude and direction of fault current. The specific behaviour of fault current during a short circuit fault demands quick and reliable detection and isolation of fault, which poses a significant challenge in developing an effective protection and coordination scheme for DC microgrids. In this regard, a new fault detection and relay coordination algorithm is proposed for a Low voltage DC (LVDC) microgrid, which utilizes inverse time relay characteristics based on variance of fault current. While the relay responds and picks up during both internal and external faults, its operation is automatically limited upon operation of the downstream circuit breaker without the need for any communication channel. The efficacy of the proposed strategy is evaluated by modelling a mesh-connected DC microgrid network using PSCAD/EMTDC software. The protection coordination problem is developed as a constraint non-linear optimization problem to determine optimal relay settings. The proposed approach has been tested by simulating various types of faults at different fault locations and fault resistances along with various microgrid operating modes. The results suggest that the proposed strategy stands out by optimizing relay operating time and providing backup protection while upholding relay coordination. A comparative assessment of the proposed technique with existing ones proves its effectiveness in terms of swift relay tripping time, better immunity against noise, and independency against microgrid operating mode and topology.

Multi‐objective optimisation framework for standalone DC‐microgrids with direct load control in demand‐side management

AbstractRenewable energy‐powered DC microgrids have emerged as a sustainable alternative for standalone power systems in remote locations, which were traditionally reliant on diesel generators (DIG) only. To ensure power quality and reliability, energy storage systems (ESS) and demand‐side management (DSM) techniques are employed, addressing the intermittent nature of renewable energy sources (RES). This manuscript presents a novel multi‐objective optimisation framework to determine the equipment sizing, depth of discharge (DoD) of ESS, and share of controllable loads contributing to DSM in a standalone DC microgrid incorporated with RES as a primary energy source and a backup DIG. The proposed optimisation strategy utilises genetic algorithm with the objectives of minimizing lifecycle cost and carbon footprint. A novel battery energy storage system (BESS) management criterion is introduced, which accounts for battery degradation in the lifecycle cost calculation. The minimum allowable DoD of the BESS is considered a decision variable in the optimisation problem to assess the impact of higher DoD on lifecycle cost improvement. MATLAB simulation results demonstrate that the proposed optimisation model significantly reduces the levelized cost of electricity and per unit carbon footprint compared to previous models. Additionally, it identifies an optimal range of DoD for the BESS to enhance the lifecycle cost of a standalone DC microgrid.

Distributed control for DC microgrids with cyber attacks and constraints: A fault-tolerant model predictive controller

Communication security issues pose severe challenges to stability of microgrid system. This paper designs a cooperative control method based on fault-tolerant distributed model predictive control (DMPC) for DC microgrid against possible false information injection (FDI) attacks and communication constraints problems. First, a state variable is defined based on the voltage and current information, thereby deriving a system model of the microgrid under the cyber-physical framework. Then, since a combined uncertainty term consisting of attacks and disturbances exists in the constructed system model, an expanded state observer (ESO) is proposed to observe the uncertainty term. Further, based on the constructed system model and the designed ESO, a fault-tolerant distributed model predictive controller is designed. In the controller, DMPC is utilized to constrain the communication information and ensure the boundedness of the communication state and physical state. Simulation results indicate that the proposed DMPC-based distributed control method can achieve stable voltage regulation and accurate current sharing, and maintain smooth operation even under FDI attack, which verifies the feasibility for the proposed method.

A wild horse-assisted decentralized control strategy for a PV-battery energy storage system in a DC microgrid

A wild horse-assisted decentralized control strategy for a PV-battery energy storage system in a DC microgrid

Controller Design for Autonomous Direct Current Microgrid Operation

Controller Design for Autonomous Direct Current Microgrid Operation

Research on large-signal stability of SOFC-lithium battery ship DC microgrid

Aiming at the solid oxide fuel cell (SOFC) applied to the ship DC microgrid in the face of pulse load disturbance is prone to make the SOFC voltage drop too large leading to the DC grid oscillation problem. In this paper, a stability criterion method for SOFC-Li battery DC system based on hybrid potential function is proposed. Firstly, a mathematical model of shipboard DC microgrid with SOFC-Li battery is established and the accuracy of the model is verified. Then, the stability criterion of the system based on the hybrid potential function under large disturbances is constructed. Subsequently, the effects of system stability under impulse load conditions were analysed under different parameters. Based on the constructed criterion, simulation verification of the stability boundary conditions of the SOFC system operating independently or jointly with a lithium battery system is carried out. The experimental results show that the proposed stability criterion and control strategy are effective in accurately predicting the system stability boundary. The experimental results verify the effectiveness of the proposed method in improving the stability of the system and provide a theoretical basis for further research on the dynamic characteristics of SOFC systems under complex load conditions.