Microgrid Configuration Research Articles

Highly Available Nuclear Power in a Microgrid Configuration for the ORNL Distribution System

A previous study concluded that the robust, multimodule design of the NuScale small modular reactor plant can provide power at an unprecedented level of availability to mission critical facilities. This study extends the analysis to include a microgrid power distribution and delivery system to demonstrate the increased availability of power delivered to a customer. A hypothetical 12-module NuScale plant located on the Clinch River site in Tennessee is assumed to supply power from three modules to Oak Ridge National Laboratory (ORNL) through the Tennessee Valley Authority (TVA) transmission system. Combinations of transmission and power generation equipment failures that might interrupt power, and the associated frequency and duration of these failures, are identified and the potential for power interruption to ORNL is evaluated. The analysis first evaluates the existing transmission infrastructure and availability of power to ORNL to establish a baseline availability. Then, a connection from the NuScale plant through the local TVA transmission system (option 1) and a direct connection from the NuScale plant to the ORNL distribution system (option 2) are evaluated, as well as three sensitivity cases. The existing power distribution and delivery system at ORNL is already highly reliable resulting from multiple diverse power generators feeding a robust power delivery system. The primary driver of macrogrid power unavailability is the existing power generation sources, which includes two coal plants and two hydroelectric generators, rather than transmission equipment. Adding a 12-module NuScale plant to the system further reduces the unavailability of power to ORNL by over two orders of magnitude in both cases of considering only local power sources and the macrogrid as a whole. When considering only local generators, the inclusion of a NuScale plant improves the average availability of power to ORNL from three-nines to over five-nines. If the large-scale macrogrid is also included, average availability is increased to nine-nines.

A novel intelligent ultra-local model control-based type-II fuzzy for frequency regulation of multi-microgrids

Due to the random nature of renewable energy in the micro-grid (MG) configuration, the energy generators in such systems are not able to offer an uninterrupted power and a mismatch between the demand and generation will be occurred. To alleviate this unbalance, technically, conventional storage devices are one of the practical solutions to this issue. However, the implementation of storage system is not effective from the economic preceptive and, as an alternative, the battery of electric vehicle can be also embedded in the structure of the MGs. In this work, an ultra-local model (ULM) controller based on a single-interval type-II fuzzy logic (SIT2-FL) controller is applied for frequency regulation of multi-MG(s) with electric vehicles. In this scheme, the ULM controller plays a critical role in the reducing the dependency of the controller to the MG model. An extended observer error is embedded in the structure ULM controller to remove the uncertainties included in the system. The SIT2-FL is established as supplementary controller to remove the error of observer and further ameliorate the multi-MG performance. Comparative simulation analysis and robustness examination are made to ascertain the usefulness of the suggested ULM controller-based SIT-FL.

Optimization of the Configuration and Operating States of Hybrid AC/DC Low Voltage Microgrid Using a Clonal Selection Algorithm with a Modified Hypermutation Operator

The issue of optimization of the configuration and operating states in low voltage microgrids is important both from the point of view of the proper operation of the microgrid and its impact on the medium voltage distribution network to which such microgrid is connected. Suboptimal microgrid configuration may cause problems in networks managed by distribution system operators, as well as for electricity consumers and owners of microsources and energy storage systems connected to the microgrid. Structures particularly sensitive to incorrect determination of the operating states of individual devices are hybrid microgrids that combine an alternating current and direct current networks with the use of a bidirectional power electronic converter. An analysis of available literature shows that evolutionary and swarm optimization algorithms are the most frequently chosen for the optimization of power systems. The research presented in this article concerns the assessment of the possibilities of using artificial immune systems, operating on the basis of the CLONALG algorithm, as tools enabling the effective optimization of low voltage hybrid microgrids. In his research, the author developed a model of a hybrid low voltage microgrid, formulated three optimization tasks, and implemented an algorithm for solving the formulated tasks based on an artificial immune system using the CLONALG algorithm. The conducted research consisted of performing a 24 h simulation of microgrid operation for each of the formulated optimization tasks (divided into 10 min independent optimization periods). A novelty in the conducted research was the modification of the hypermutation operator, which is the key mechanism for the functioning of the CLONALG algorithm. In order to verify the changes introduced in the CLONALG algorithm and to assess the effectiveness of the artificial immune system in solving optimization tasks, optimization was also carried out with the use of an evolutionary algorithm, commonly used in solving such tasks. Based on the analysis of the obtained results of optimization calculations, it can be concluded that the artificial immune system proposed in this article, operating on the basis of the CLONALG algorithm with a modified hypermutation operator, in most of the analyzed cases obtained better results than the evolutionary algorithm. In several cases, both algorithms obtained identical results, which also proves that the CLONALG algorithm can be considered as an effective tool for optimizing modern power structures, such as low voltage microgrids, including hybrid AC/DC microgrids.

Modeling and Performance Assessment of the Split-Pi Used as a Storage Converter in All the Possible DC Microgrid Scenarios. Part II: Simulation and Experimental Results

Bidirectional DC/DC converters such as the Split-pi can be used to integrate an energy storage system (ESS) into a DC microgrid providing manifold benefits. However, this integration deserves careful design because the ESS converter must behave like a stiff voltage generator, a non-stiff voltage generator, or a current generator depending on the microgrid configuration. Part I of this work presented a comprehensive theoretical analysis of the Split-pi used as an ESS converter in all the possible DC microgrid scenarios. Five typical microgrid scenarios were identified. Each of them required a specific state-space model of the Split-pi and a suitable control scheme. The present paper completes the study validating the theoretical analysis based on simulations and experimental tests. The chosen case study encompassed a 48 V, 750 W storage system interfaced with a 180 V DC microgrid using a Split-pi converter. It can represent a reduced-power prototype of terrestrial and marine microgrids. A prototypal Split-pi converter was realized in the lab, and several experimental tests were performed to assess the performance in each scenario. The results obtained from the experimental tests were coherent with the simulations and validated the study.

OPTIMALISASI KAPASITAS ENERGI ANGIN DAN MATAHARI DENGAN KONFIGURASI MIKROGRID BERDASARKAN KARAKTERISTIK BEBAN

Diploma III Electrical Technology Study Program is a institutional vocational education institutional in Department of Electrical Engineering and Informatics that aims to produce graduate who are ready to work in operation and maintenance of power system. Since phenomena of scarcity of fossil fuels, study program meet the 2 major problems, namely the limitations of electrical energy for practical lab work and increased job skills on the electrical energy conversion of electrical energy from renewable energy. The purpose of this research is to optimalize capacity of solar and wind energy contained in the environment of the laboratory on the microgrid configuration, namely PV-Wind turbine-Battery. Software HOMER is used to simulate microgrid configuration with AC-DC load, AC load, and DC load. The results show indicate that microgrid PV-Wind turbine-Battery is more economically to meet the need AC-DC load than the others.

Differential evolution algorithm based on PCA to determine the objective function to optimize the configuration of microgrid

Recently, microgrids are increasingly used in our lives. The purpose of this paper is to solve the uncertainties of multi-objective decision-making and the instability of algorithms in the optimal configuration of traditional microgrids. This paper proposed a differential evolution algorithm based on PCA to determine the objective function. Firstly, a multi-objective optimization model of the micro-grid was established on the basis of fully considering the economy, environmental protection and stability of the micro-grid. Next, the first principal component of the multi-objective was extracted based on PCA combining innovatively the Pareto optimal solution set, and the multi-objective optimization problem was transformed into a single-objective optimization problem. Finally, the experimental simulation result shows that the algorithm proposed in this paper can comprehensively consider the economy, environmental protection and stability of the microgrid on the basis of ensuring the efficiency and stability of the algorithm to realize the optimized configuration of the microgrid.

Multi-objective optimization configuration of wind-solar-storage microgrid based on NSGA-III

Reasonable allocation of the capacity of micro power supply such as wind turbine, photovoltaic and battery is the premise to ensure the economic, reliable and environmental protection operation of microgrid. Aiming at the capacity allocation problem of grid connected microgrid, this paper establishes a multi-objective optimal allocation mathematical model of grid connected microgrid considering the economy, reliability and environmental protection of microgrid, and uses the genetic algorithm NSGA-III based on the reference point selection mechanism to obtain the multi-objective Pareto solution set of micro source capacity allocation. The simulation results show that NSGA-III can not only optimize the three objective functions better than NSGA-II, but also improve the distribution uniformity of Pareto solution set and the diversity of population. The simulation results show that NSGA-III algorithm is more suitable for multi-objective optimal configuration of microgrid.

A rule-based power management strategy for Vehicle-to-Grid system using antlion sizing optimization

Stable and reliable electricity is a prerequisite to the development of any nation and improving the living standard of the society. By exploiting Renewable Energy Sources (RESs) such as solar energy (PV) and wind energy (WT) as widely acknowledged RESs to be more environmentally friendly and address power difficulties. They are acknowledged to be an interesting option to charge Electric Vehicles (EVs) via Vehicle-to-Grid (V2G) technology. On the contrary, to the best knowledge of the authors, there are few numbers published articles on RESs (PV and WT) integrated with Electric Vehicle Charging Station (EVCS) to charge EVs. This research is aimed at implementing a metaheuristic optimization algorithm named Antlion Optimizer (ALO) algorithm for sizing the system components to meet the load demand and minimize the two objective functions - Losses Power Supply Probability (LPSP) and Cost of Electricity (COE) while maximizing the Renewable Energy Fraction (REF). In addition, the Rule-Based Energy Management Strategy (RB-EMS) is proposed to control the flow of power in the system. The integration of RESs to the utility grid with V2G technology and V2G services is discussed. Furthermore, the State-of-the-art for improving the stability and reliability of the grid-connected system is presented. As a result, the attained result from the proposed method shows better performance results as 0.0936 $/kWh, 0.1044%, and 0.9940% for COE, LPSP, and REF, respectively. The research is conducted in different microgrid configurations using a MATLAB environment.

Techno Economic Evaluation of Hybrid Energy Isolated Micro-Grids for Rural Areas in Four Zones of Egypt

In this paper, Rural electrifications and optimum sizing of isolated hybrid micro-grids improve the quality of the life in rural areas by using the optimization technique. A software homer optimization technique has been used to model isolated micro-grid performance during a time of one year, considering hourly variations in both the availability of renewable resources and variations in load demands. The optimum solution is obtained considering the minimization of the levelized costs of energy (LCOEs) over a project lifetime of 25 years. The simulations concentrated on the net present costs (NPCs), LCOEs, and a renewable fraction (RFs) of the given hybrid isolated micro-grids for all four zones. The gotten analyses show that SPV/wind/diesel/battery storage hybrid isolated micro-grids configuration is found as optimal solutions for 1.3 $/l of diesel fuel consumption. This paper studied the feasibility of different isolated micro-grid configurations comprising SPV, WT, and diesel in different areas of Egypt. Four rural isolated micro-grids have been randomly chosen for the four areas in Egypt with the intention that the obtained results of this study could be replaced in other rural locations of the selected areas with similar terrains. HOMER simulation was used to calculate the economic feasibility of the isolated micro-grids. The simulations focused on the LCOEs and RFs of the given hybrid component for all four regions. The analyses showed that SPV/wind/diesel/battery hybrid isolated micro-grids configuration is found as the best architecture for all rural areas. It also presented a good performance in fuel consumption and CO2 reduction.

An optimization study on a typical renewable microgrid energy system with energy storage

In isolated microgrids and remote regions, the challenge of developing reliable and self-sufficient renewable energy systems is amplified due to the lack of grid flexibility options. One of the leading solutions to increase renewable energy usage in isolated systems is the commission of energy storage. The current study proposes a novel optimization model that sizes the most cost-efficient renewable power capacity mix of an autonomous microgrid supported by storage technologies. The proposed algorithm considers operational, technical and land-use constraints. The problem is formulated using linear programming, is tested and scrutinized with sets of historical weather, load demand and installation prices data, and is modelled hour-by-hour. The method is applied to Corvo, an island in the Azores archipelago, Portugal. The results obtained exhibit that the proposed approach provides the optimal configuration of the renewable-based microgrid with an LCOE (Levelized Cost of electricity) of 0.21 €/kWh, a value lower than a diesel-based alternative, and while ensuring minimum land area occupation. Furthermore, sensitivity analysis is also presented to examine the effect of variables on the LCOE and PC (present cost) of the system. The present study shows that the developed optimal sizing model can improve electricity planning and facilitate energy transition in distributed power systems.

Optimization of Multiobjective Configuration of Multienergy Microgrid Based on HMM and Typical Scenarios: A Case Study of Smart Park

Decentralized regional multienergy system is one of the important development directions of energy and power systems, and researching on the optimization method of multienergy microgrid configuration could provide important support for the investment income guarantee and orderly development of regional multienergy systems. Based on a park-level multienergy microgrid, this paper proposed a multiobjective optimization model for a multienergy microgrid configuration based on the typical scenario set which was constructed by HMM. Besides, based on the actual historical data, the capacity configuration-oriented planning model and component configuration-oriented planning model were analysed and compared under different external environments. The results show that HMM has a good effect on the reduction and extraction of historical scenarios of the system. Compared with the traditional microgrid, the multienergy microgrid has better economic and emission reduction advantages. In addition, the capacity configuration-oriented planning model could reduce the investment cost by up to 62.4% compared with the component configuration-oriented planning model.

Planning and reliability of DC microgrid configurations for Electric Vehicle Supply Infrastructure

Infrastructures for Electric Vehicle feeding, providing smart charging, vehicle-to-grid and local generation are of increasing interest. The operation of these systems and the integration with distribution networks can gain remarkable improvement by proper DC microgrid structure, able to reduce losses in converters, to improve controllability and to enhance overall availability. In this paper, a procedure for optimal planning of a DC microgrid for Electric Vehicle Supply Infrastructure is carried out, with specific tailoring according to technical configurations for source connection, involving different converter types and topologies. The procedure is completed by a reliability analysis, where rule-based curtailment is performed with multi-state matrix approach, and the effect of expected energy not supplied on total cost is evaluated, at different integration levels of energy storage. The proposed approach is applied to a case study of envisaged demonstrator for an Electric Vehicle service fleet.

A new voltage regulation strategy using developed power sharing techniques for solar photovoltaic generation-based microgrids

Integration of solar photovoltaic (PV) sources to power grid is increasing rapidly in recent years. Since the PV source is an intermittent source, this causes many challenges to distribution network. To overcome these challenges, a voltage regulation strategy using a developed power management technique for microgrid system is proposed. The technique is based on voltage ride through capability. The active and reactive power flow along with the voltage profile has been deeply investigated to improve the stability of the distribution network. As a testing environment, three microgrid configurations developed in MATLAB/Simulink have been investigated. The study shows a faster response time and lower circulating current in configuration 2. Moreover, it revealed the effectiveness of the power management technique when a cluster of dispatchable and non-dispatchable distributed generators is in operation.

Automatic Generation Control Strategies in Conventional and Modern Power Systems: A Comprehensive Overview

Automatic generation control (AGC) is primarily responsible for ensuring the smooth and efficient operation of an electric power system. The main goal of AGC is to keep the operating frequency under prescribed limits and maintain the interchange power at the intended level. Therefore, an AGC system must be supplemented with modern and intelligent control techniques to provide adequate power supply. This paper provides a comprehensive overview of various AGC models in diverse configurations of the power system. Initially, the history of power system AGC models is explored and the basic operation of AGC in a multi-area interconnected power system is presented. An in-depth analysis of various control methods used to mitigate the AGC issues is provided. Application of fast-acting energy storage devices, high voltage direct current (HVDC) interconnections, and flexible AC transmission systems (FACTS) devices in the AGC systems are investigated. Furthermore, AGC systems employed in different renewable energy generation systems are overviewed and are summarized in tabulated form. AGC techniques in different configurations of microgrid and smart grid are also presented in detail. A thorough overview of various AGC issues in a deregulated power system is provided by considering the different contract scenarios. Moreover, AGC systems with an additional objective of economic dispatch is investigated and an overview of worldwide AGC practices is provided. Finally, the paper concludes with an emphasis on the prospective study in the field of AGC.

Optimal Design of an Isolated Hybrid Microgrid for Enhanced Deployment of Renewable Energy Sources in Saudi Arabia

Hybrid microgrids are presented as a solution to many electrical energetic problems. These microgrids contain some renewable energy sources such as photovoltaic (PV), wind and biomass, or a hybrid of these sources, in addition to storage systems. Using these microgrids in electric power generation has many advantages such as clean energy, stability in supplying power, reduced grid congestion and a new investment field. Despite all these microgrids advantages, they are not widely used due to some economic aspects. These aspects are represented in the net present cost (NPC) and the levelized cost of energy (LCOE). To handle these economic aspects, the proper microgrids configuration according to the quantity, quality and availability of the sustainable source of energy in installing the microgrid as well as the optimal design of the microgrid components should be investigated. The objective of this paper is to design an economic microgrid system for the Yanbu region of Saudi Arabia. This design aims to select the best microgrid configuration while minimizing both NPC and LCOE considering some technical conditions, including loss of power supply probability and availability index. The optimization algorithm used is Giza Pyramids Construction (GPC). To prove the GPC algorithm’s effectiveness in solving the studied optimization problem, artificial electric field and grey wolf optimizer algorithms are used for comparison purposes. The obtained results demonstrate that the best configuration for the selected area is a PV/biomass hybrid microgrid with a minimum NPC and LCOE of $319,219 and $0.208/kWh, respectively.

Differential evolution algorithm based on entropy weight method to determine the weight to optimize the configuration of wind, solar, and diesel microgrid

In order to enhance the stable operation of the multi-energy complementary microgrid for wind, solar, and diesel storage, reduce operating costs, and solve the problems of large randomness, low accuracy, and slow convergence of traditional microgrid optimization multi-objective decision-making, a differential evolution based on the entropy weight method to determine the weight is proposed. Firstly, we establish a microgrid integrated energy model from the perspectives of system operation stability, economy and environmental protection; combined with the Pareto optimal solution set, multi-objectives are weighted according to the entropy weight method, and the multi-objective optimization problem is transformed into single-objective optimization The problem is to avoid artificial setting of weight factors; the calculation example shows that this method is more economical and reasonable in optimization results, and provides an economic, reliable and environmentally friendly microgrid configuration strategy for users to increase power capacity.

Higher Order Sliding Mode Observer-Based Sensor Fault Detection in DC Microgrid’s Buck Converter

Fault detection in a Direct Current (DC) microgrid with multiple interconnections of distributed generation units (DGUs) is an interesting topic of research. The occurrence of any sensor fault in the DC microgrid should be detected immediately by the fault detection network to achieve an overall stable performance of the system. This work focuses on sensor fault diagnosis of voltage and current sensors in interconnected DGUs of the microgrid. Two separate higher order sliding mode observers (HOSM) based on model dynamics are designed to estimate the voltage and current and generate the residuals for detecting the faulty sensors in DGUs. Multiplicative single and multiple sensor faults are considered in voltage and current sensors. By appropriate selection of threshold, single and multiple sensor fault detection strategies are formulated. A hierarchical controller is designed to ensure equal sharing of current among the DGUs of the DC microgrid and stabilize the system. Simulations are performed to validate the proposed approach for various configurations of the DC microgrid under various load and off noise conditions.

New Decentralized Control of Mesh AC Microgrids: Study, Stability, and Robustness Analysis

In this paper, we investigated the power sharing issues in mesh islanded microgrids that contain several distributed generators (DGs) and loads connected to different points of common coupling (PCC). Firstly, an improved decentralized droop control algorithm is proposed to achieve the active and reactive power sharing of different DGs in reconfigurable mesh islanded microgrids. Accurate power sharing was obtained even though line parameters or the mesh microgrid configuration were unknown. Secondly a state-space model of the whole mesh microgrid was developed, considering several generators with their decentralized controllers, line feeders, and dynamic loads. This model was used to design parameters of droop controllers, to study the asymptotic stability and the robustness properties of the system. All strategies and analyses were validated by simulation based on the generic microgrid detailed in the standard IEEE 9bus test feeder.

Impact of emergency diesel generator reliability on microgrids and building-tied systems

Microgrids are an emerging alternative as an energy backup system for critical electric loads and have improved performance compared to the traditional architecture where a single emergency diesel generator is tied to an individual building. Both architectures are dependent on the reliability of their individual generators and a quantitative and realistic comparison of the overall system reliability of the two architectures is lacking. Using recently published work on emergency diesel generator finite reliability, a quantitative methodology is presented to compare the reliability of a microgrid architecture based on centralized emergency diesel generators to the traditional approach of generators tied to individual buildings. Three system reliability performance metrics are calculated as a function of outage duration: (1) probability to meet 100% of the critical load; (2) expected fraction of lost load; and (3) probability to meet the highest priority critical loads. It is shown that stand-alone building-tied emergency diesel generators systems, even when two emergency diesel generators are used per building, cannot provide the reliability required to sustain critical loads for a grid outage lasting multiple days. Due to their network configuration and ability to share load, diesel generator-based microgrid configurations are estimated to have ≥ 93% probability of powering all buildings for a 2-week outage there the individual building-tied emergency diesel generator architecture has a ≤20% probability. Microgrids do present other susceptibilities that are site specific and should be considered including vulnerabilities associated with the on-campus distribution system and cybersecurity.

Design Framework of a Stand-Alone Microgrid Considering Power System Performance and Economic Efficiency

Stand-alone microgrids integrating renewable energy sources have emerged as an efficient energy solution for electrifying isolated sites, such as islands and remote areas. The design of a microgrid involves various influential factors, including technological development, economic feasibility, and environmental impacts, based on the conditions and regulations of a particular site. This paper proposes a comprehensive microgrid design framework based on power system analysis and techno-economic analysis. The obtained optimal microgrid configuration satisfies both the design objective and power system performance regulations. The proposed design approach focuses on using practical data and can adapt to any microgrid design problems based on the local characteristics of a specific site. The practicality and effectiveness of the design framework are validated by applying it to the design of a stand-alone microgrid for Deokjeok Island in South Korea. The case study results justify the importance of considering site-specific characteristics and the impacts of power system conditions on the optimal microgrid design.