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Load survey has become a routine project for shipbuilding and shipping companies to investigate electrical load characteristics to enhance the power system planning and operation of marine vessels. In this brief perspective, we will outline a few steps to feeder losses analysis based on the result conducted by the load survey. The power flow and feeder loss analysis are extracted and used to determine the critical parameters that can significantly affect the system feeder losses used in the electrical load analysis in new ships. Exploring this new research direction will provide a more thorough understanding of feeder losses in marine vessel power systems. In this paper, a case study of container ship power loss analysis using the Newton–Raphson method is presented. The analysis results can provide shipbuilding corporations and ship owners with useful information for planning, designing, operating, and controlling shipboard power systems. As an energy-saving measure for ship microgrids, the frequency converters are widely used by shipyards for seawater and freshwater cooling systems and heating, ventilation, and air conditioning (HVAC) systems, so that these systems can adjust the speed of the motor according to the actual demand of the load, so as to avoid full-load operation during the motor operation. With the proposed method, other measures, such as battery energy storage systems and energy-saving lighting equipment based on LEDs, are also utilized for shipboard power demand management. [ABSTRACT FROM AUTHOR]

This article presents the calculation procedure of short circuits adopting the characteristic currents method (CCM). In a previous paper by the author G. Parise, the CCM has been upgraded with the introduction of “characteristic” countercurrents and the generalization of the Kirchhoff laws. For illustrating the calculation procedure, the selected case study deals with a low voltage cold ironing system where multiple ships are allowed to operate simultaneously on one shore power transformer and, so, a comparison has been developed between the IEC approach of the short-circuit calculation and the CCM. [ABSTRACT FROM AUTHOR]

This article presents a robust passivity-based control (PBC) strategy to mitigate the instability effect of the dc–dc boost power converter supplying a constant power load and a constant voltage load in dc microgrid systems. The control robustness of the PBC against both line and load variation is significantly improved by adding the nonlinear disturbance observer (NDO). Using the disturbance estimation technique, this observer works in parallel with the PBC strategy to compensate the disturbances of the system through a feed-forward compensation channel. Based on the dissipation property, the PBC strategy ensures the system stability, whereas the NDO guarantees global trajectory tracking to the reference voltage during disturbances. This control strategy not only ensures large-signal stability of the system, but also provides a fastest recovery performance during disturbances of the system as compared with other PBC strategies. The hardware-in-loop and real-hardware experimental results are provided to verify the control robustness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

In recent years, due to the large spread of power electronics converters onboard shipboard power systems (SPSs), harmonic contamination became an inherent problem. Moreover, as the SPSs are mostly operating in an islanded mode with a limited rating of the generators that feed heavy variable loads, voltage stability issues became a challenge as well. To address these issues, implementing PWM-based FACTS devices using IGBTs such as the active power filters may not be very practical for high-power SPSs due to their limited rated powers, high implementation cost, and high losses. The passive power filters (PPFs) and fixed capacitor–thyristor controlled reactors (FC-TCR) can be effective alternatives due to their capability to operate in high-power applications, smaller losses and, lower cost. The aim of this article is to provide more in-depth analytical investigations to evaluate and compare the behavior of the PPFs and the FC-TCR compensator in reducing the harmonics and enhancing the voltage stability concurrently of high-power SPSs. In addition, details of the voltage stability concept are addressed to visualize the potential risk of the voltage collapse. Besides, the modeling of the FC-TCR and design of the closed-loop control algorithm to ensure voltage stability is conducted. Via intensive simulation studies of a practical ship, which are carried out in MATLAB/Simulink environment, it has been demonstrated that the FC-TCR based on the proposed design can enhance the power quality and voltage stability of SPSs better than traditional PPFs filters. [ABSTRACT FROM AUTHOR]

Addressing power quality issues in shipboard microgrids (SMs), which are mainly attributable to the increased installation of power converters, has received much attention recently. To this end, static VAR compensators, such as thyristor-switched capacitors and fixed capacitors-thyristor controlled reactors (FCs-TCRs), can be effective solutions. Controlling these compensators, however, is not a trivial task as it involves sophisticated operations, especially estimating the firing angle, which should be carried out based on some nonlinear equations. This article aims to propose the application of some simple yet numerically efficient algorithms based on bisection, Newton–Raphson, false position, and secant methods for estimating the firing angle of the FC-TCR. The effectiveness and robustness of these algorithms are demonstrated via modeling of the FC-TCR with the electrical power system of a practical hybrid ferry under MATLAB/Simulink environment, where the results proved that the enhanced power quality issues respect the IEC standards 61000-4-7/30. Furthermore, an experimental setup consists of a digital signal processor and a programmable source is used to demonstrate that these techniques can be effectively applied in real-time applications. [ABSTRACT FROM AUTHOR]

Electric load analysis is an important task in early new stage for design of shipboard power systems (SPSs). The installation generation capacity onboard depends on the accurate result of the analysis, which significantly affects the system economic and secure operations. In the traditional electrical load analysis, the demand factor is often obtained from engineering experiences which may lead to inaccurate analysis results. In order to obtain better results, a methodology for electrical load analysis in SPSs is proposed in this article. The load analysis spreadsheet is adopted to find the power consumption of key electric loads in SPSs. The actual power consumptions of selected loads are collected by intelligent meters. The statistical analysis is then performed to find the critical parameter of each selected load in the load analysis under different operating conditions based on the power measurement of field test and load analysis is performed for estimating system power demand accordingly. The large practical maritime vessel power systems are selected for numerical analysis to ensure the performance of the proposed method. The proposed method has been adopted by local ship builders in Taiwan to better understand the load characteristics in shipboard power systems to support various functions of system planning and operation in a more effective manner. [ABSTRACT FROM AUTHOR]

Seaports are specifically designed for trading purposes. They are equipped with facilities for handling industrial and commercial goods as well as raw materials stored in containers. These facilities are often based on diesel cranes, which are noisy and produce air pollution. A possible solution to address this problem is replacing the diesel-power cranes with the electric ones. This idea, however, demands a high power connection to the grid in the seaport. This paper presents a cost-effective and environmentally friendly solution based on an electrical flywheel system to reduce electricity consumption from the electrical power network while improving system efficiency by using already existing technologies. Besides, this study presents a new method for controlling electrical drives using flywheel energy storage systems in harbor crane applications by exploiting the energy harvested from the cranes. The system model, including the electrical grid, cranes, power electronic drives, and flywheels as energy storages, is presented and an effective control methodology is developed. Simulation results of a practical crane system are presented and discussed. Practical lab-scale setup is also built and tested. The results have shown that by using the proposed method, the energy can be effectively harvested from the crane into the flywheel energy storage system during its operation, which significantly enhances the harbor power system efficiency as well as supply quality. [ABSTRACT FROM AUTHOR]

For a variety of reasons, it is becoming an increasingly common requirement for ships to shut down ship generators and connect to high voltage shore power for as long as practicable while in port. Ship electrical equipment shall only be connected to shore supplies that are able to maintain harbor electrical distribution system voltage quality. Voltage drop, which is produced by the possible loading conditions of a ship when connected to a shore supply, may result in unsatisfactory operation of, and damage to, electrical and electronic equipment on board, and thus must be considered in the harbor distribution system design in order to comply with the requirements of international standards. A simple and fast method able to estimate the expected magnitude of voltage drops and provide information about the effectiveness of the various mitigation methods is essential. This paper presents the methodology and results for evaluation of the voltage drops of a practical harbor electrical distribution system with high voltage shore connection (HVSC). The potential voltage drops of the implemented HVSC are quantified using standard analytical formulas. Sensitivity analysis is performed to determine the critical parameters that significantly affect voltage drops. The parameters that have great improvement benefits should have high priority for implementation in other distribution systems with HVSC. The results obtained in this paper can provide engineers with useful information regarding the actual magnitude of voltage drops, as well as on the effectiveness of mitigation options for voltage drops, which would greatly enhance HV shore supply quality. [ABSTRACT FROM PUBLISHER]

One of the most basic tasks for ship power system design is electrical load analysis, which is used to determine the required installed capacity of on-board power generators. Traditionally, the analysis is carried out based on considerations of investment cost and supply adequacy, while using a design of generators with the same rating. It does not consider the energy efficiency, thereby in some cases resulting in the generators operated at a lower efficiency under heavy loading conditions and high energy consumption. To enhance power generation efficiency and reduce energy cost, a new load analysis method for marine vessels is proposed in this paper. The relationship of operating efficiency and load factor of generators is mathematically modeled and considered in the analysis. The problem is formulated as a nondifferential combinational optimization problem, where the total generation cost during a whole voyage is minimized subject to system operation and technical constraints, in order to derive the optimal generator rated power and unit commitment using genetic algorithms. The results confirmed the validity of the proposed method through load analysis of a practical ship power system, as well as energy-saving benefits using the proper generator rated power and an accurate load model for power pumps. [ABSTRACT FROM AUTHOR]

The medium-voltage dc (MVDC) distribution system is a new shipboard power distribution technology that has been extensively discussed and studied by many shipbuilding corporations and ship-owners in recent years. As different types of power converters and ac and dc power distributions simultaneously involved in the system, the system performance for different connections of generators to MVDC converters under varying steady-state operating conditions is essential and important in the design stage of the electrical power distribution system. This type of problem can be analyzed by performing power flow studies. This paper aims presenting a methodology for power flow studies in ship MVDC distribution systems for system planning purpose. A power flow model of the power converters in steady-state is derived to consider medium and low voltage characteristics of electric power system on this type of ship. An ac/dc power flow solution approach then is developed to incorporate ac-system and dc-system models and the ac/dc interface buses in the analysis for determining an appropriate connection of generators and MVDC converters and power converter setting values. Test results of two alternatives for the direct connection of generators to MVDC converters under varying steady-state operating conditions are presented and compared to determine the proper generator-power converter scheme. [ABSTRACT FROM AUTHOR]

A multiagent-based feeder automation system is developed for the service restoration of power systems in a navy ship after fault contingencies. In the system, power-electronic-building-block agents of the multiagent system (MAS) are used to derive the proper restoration plan after the faulted location is identified and isolated. To assure that the restoration plan complies with operation regulation, heuristic rules based on standard operation procedures of the shipboard power system (SPS) are included in the best first search of the MAS. Two control schemes for SPS restoration are investigated, and their performances are evaluated and compared using a discrete event simulation technique with respect to restoration time. For fault contingency when the capacity reserves of supporting feeders are not enough to cover the fault restoration, the load shedding strategy is derived for the MAS to restore service power to as many key loads as possible. A navy SPS with 72 feeders is selected for computer simulation to demonstrate the effectiveness of the proposed methodology. The study concludes that, to cover feeder automation functions, a MAS with distributed processing capability provides better reliability performance than the centralized control. [ABSTRACT FROM PUBLISHER]

A stochastic modeling and simulation technique for analyzing impacts of electric vehicles charging demands on distribution network is proposed in this paper. Different from the previous deterministic approaches, the feeder daily load models, electric vehicle start charging time, and battery state of charge used in the impact study are derived from actual measurements and survey data. Distribution operation security risk information, such as over-current and under-voltage, is obtained from three-phase distribution load flow studies that use stochastic parameters drawn from Roulette wheel selection. Voltage and congestion impact indicators are defined and a comparison of the deterministic and stochastic analytical approaches in providing information required in distribution network reinforcement planning is presented. Numerical results illustrate the capability of the proposed stochastic models in reflecting system losses and security impacts due to electric vehicle integrations. The effectiveness of a controlled charging algorithm aimed at relieving the system operation problem is also presented. [ABSTRACT FROM PUBLISHER]

Variable-frequency-drive (VFD) applications are gradually being recognized by maritime industries as one of the most effective tools for energy savings. Significant energy benefit can be realized from VFD-driven central seawater cooling systems because the ambient seawater temperature varies greatly as ships travel through different sea areas. Before making a decision about which drive to choose, information about the actual energy and cost savings is needed. A simple and fast method that is able to effectively determine the energy savings for closely estimating the economics for their application is essential. This paper aims at presenting a fast method for calculating energy savings that would result from installing VFDs on the seawater cooling pumps on ships. The ship main engine cooling system and navigation environment characteristics, including related marine equipment, pipe allocation, ambient seawater temperature, etc., are taken into account. The process system that involves mechanical, instrumental, and pump hydraulics, as well as the electrical aspects of the drive, is mathematically modeled so that the pump hydraulic formulas can be properly applied. The performance of the proposed method was validated through the energy-savings analyses of an actual ship seawater cooling system. The effect of shipping routes on the energy savings was fully described. The analysis model developed in this paper can assist in performing the energy-savings calculations to permit the checking of the economics of adjustable-speed flow control for similar systems in industrial applications. [ABSTRACT FROM PUBLISHER]

A poor power factor is often overlooked in ship power systems where electric motors are widely used to drive a variety of machinery and operate numerous processes. By reducing the reactive power produced by power generators through power factor correction (PFC), not only have system operating efficiency and economic targets been enhanced but greenhouse gas emissions have been also reduced. An evaluation of the economics of power factor improvement should take into account diesel electric generator loading, fuel oil consumption rate, running time, operating efficiency, and the production of emissions. This will help achieve energy-saving evaluation and ensure that the additional capital costs of installing a PFC system will provide an adequate rate of return on investment. This paper presents the methodology and results for the economic evaluation of PFC in marine vessels. A mathematical model, used to determine the relationships among fuel oil consumption, emission, and power factor for the diesel electric generator, is derived to quantify the possible benefits with PFC. An economic evaluation method using present worth analysis is performed to evaluate the PFC system. Numerical analysis and field test of practical ship power systems confirm the validity of the proposed approach and the critical parameters for PFC economics are determined. [ABSTRACT FROM PUBLISHER]

Variable-frequency speed control technologies are widely used in chilled water pumps in clean room heating, ventilation, and air-conditioning (HVAC) systems in high-tech industries to reduce energy consumption. Pumps with variable frequency drivers work based on the reading from the differential pressure sensor placed between the chilled water supply and return lines before the secondary and tertiary pumps. The determination of the differential pressure setpoint must take pipeline topology and material, chilled water flow demand, heat loading, and system equipment aging into account so as to provide operating flexibility for energy conservation while ensuring the secure operation of the clean room. To enhance clean room energy efficiency, a new methodology is proposed in this paper for determining the proper chilled piping pressure setpoint for the pumps. The mathematic model of head loss required for generic secondary and tertiary chilled networks widely used in clean rooms is derived using the Hazen–Williams formula principle. The field testing results confirm the validity of the proposed approach through a practical clean room HVAC system for electronic semiconductor manufacturing, and the energy savings and investment benefits due to the use of the proper differential pressure setpoint are determined. [ABSTRACT FROM PUBLISHER]

Induction motors are widely used in ship electrical power applications as they are frequently switched on into the supply system, consuming about 70% of the electrical energy generated. Voltage sag, which is produced by the starting current of induction motors, is one of the main causes of sensitive equipment dropout and, as such, must be considered in ship electrical system designs to comply with classification societies' rules. A simple and fast method that is able to estimate the expected magnitude of voltage sag disturbances and provide information about the effectiveness of the various mitigation methods is essential. This paper aims at presenting a faster evaluation method for voltage sags due to motor start-ups in ship electrical power systems. The performance of the proposed method is validated by measurements gathered from several motor starter designs in practical ship power applications using the Riemann-summation-principle-based evaluation method. The proposed method can provide engineers with useful information about the actual magnitude of sag disturbances as well as on the effectiveness of motor starters for ship electrical power applications, which will assist them in determining proper motor starter designs. [ABSTRACT FROM AUTHOR]

To increase the competition in the future global shipbuilding markets, CSBC Corporation, Taiwan, has started to do an expansion plan to install high efficient facilities for valuing productivity and improving efficiency of the overall plant operations. The shipyard, however, has no power SCADA system due to old building ages and cost considerations, and consequently real-time measurements for most load buses in the system are not available. For future expansion purposes, CSBC tries to develop a methodology for expansion planning of the shipyard power system. This paper presents the methodology and expansion planning results. A two-stage load estimator algorithm that combines typical load characteristics and state estimation theory is developed to provide the injected power at load buses in the network at a sound accuracy with relatively few real measurements. The estimated results that could reflect true system operation then are used as a base case for system expansion planning. A five-bus test system and the CSBC power system have been analyzed to show the good convergence characteristics of the developed estimator algorithm and to demonstrate the effectiveness of proposed methodology. [ABSTRACT FROM AUTHOR]

Abstract: Deregulation of electric power industry has motivated electricity customers to pay more attention in evaluating both the direct cost of electric service and the monetary value of reliable electric service. This movement has been recognized by the utilities and the value-based aspects are introduced into the planning and design of power systems to consider the outage costs. The value of service reliability that can portray and respond to actual utility and customer impacts as a result of power interruptions plays a major role on justifying whether a distribution automation (DA) system is beneficial or not. However, for the value of service reliability, there are a number of factors that can affect it. To exactly evaluate the service reliability value, two formulas for quantifying the customer interruption costs and utility reduced energy revenues associated with power failures are derived in this paper. The customer types, feeder loads, feeder failure rate, number of switch, restoration time, and repair time are taken into account. The proposed formulas can provide an exact estimate in outages costs of a feeder and their computation is simplified and straightforward. The estimated outage costs can then be used to calculate the reliability improvement benefit of DA systems for the system benefit–cost analysis. A practical DA system implemented by Taiwan Power Company is used to illustrate the proposed formulas and the benefit–cost analysis result is presented. Sensitivity analysis is also performed to reduce the effects of benefit–cost analysis parameters on the analysis result. [Copyright &y& Elsevier]

Various types of Special Protection Systems (SPSs) have been implemented worldwide for preventing major blackout and enhancing system reliability. For an SPS that covers a wide area, one of the main concerns in the design of the system is the effect of communication conflicts and contention between devices on the total system operation. Contention causes work to be queued or blocked from execution and system performance may suffer as a result. In this paper, a discrete event simulation technique is used to study the communication performance of an SPS. The communication system of an SPS designed for relieving transient and dynamic instability is used for the study. The system modeling presented in this paper is aimed to verify whether the hardware design could accommodate the data traffic load and to avoid overpaying for network equipments. Through simulations the interactions among all devices and the bottlenecks of the communication system can be identified. Based on the simulation results, system designers could adopt available options to increase network bandwidth or hardware capability to maintain an adequate performance of the SPS. [Copyright &y& Elsevier]

This paper introduces an innovative adaptive nonsingular Second-Order Terminal Sliding Mode (SOTSM) control strategy specifically designed to stabilise disturbed nonlinear Cyber-Physical Systems (CPSs) within a finite timeframe. Unlike the conventional methods, our approach incorporates a novel nonlinear sliding surface that eliminates the need for a reaching step, significantly enhancing the system's robustness. Novel real-time adaptive control laws are developed to cope with external perturbations, time-varying delays, and cyber-attack on actuators without requiring the identification of their upper bounds. The proposed method ensures robust performance for time-varying delayed and disturbed nonlinear CPSs, even in the face of strong cyber-attacks targeting the actuators. Moreover, the proposed method has distinct advantages: it delivers rapid response times, enhanced flexibility, exceptional accuracy, smooth and robust control devoid of transient fluctuations or chattering, and ensures finite-time convergence. Simulation results comprehensively demonstrate the superior efficiency and success of our proposed technique compared to traditional methods such as integral Sliding Mode Control (SMC) and State-Feedback Control (SFC) schemes. [ABSTRACT FROM AUTHOR]

In recent years, renewable energy (RE) has shown promise as a sustainable solution to the rising energy demand worldwide. Photovoltaic (PV) technology has emerged as a highly viable RE alternative. The majority of PV schemes use specific PV models with specified parameters. This study proposes a PV model with generic specifications, a PV array, a DC/DC converter, a DC/AC inverter, maximum power point tracking (MPPT), and grid synchronization using a feedback control system under the MATLAB/Simulink environment. Various MPPT techniques have been adapted to track the PV's maximum power point (MPP); however, there are various uncertainties. To address these challenges, this paper presented a perturb and observe (P&O) strategy to track the MPP of PV systems reliably. The MPP of a PV system varies according to meteorological order, such as solar radiation and cell temperature. The MPPT primarily gathers the maximum current and voltage of the PV array and provides them to the load using a boost converter. The MPPT performance and PV array attributes are analyzed during abrupt weather changes. Finally, a feedback controller is configured to perform synchronization of the inverter with the grid. The validity and reliability of the PV module using P&O methods provide a higher efficacy of MPPT under MATLAB/simulation. Finally, the presented results endorse the strength of the proposed technique. [ABSTRACT FROM AUTHOR]

The transmission lines of an electricity system are susceptible to a wide range of unusual fault conditions. The transmission line, the longest part of the electricity grid, sometimes passes through wooded areas. Storms, cyclones, and poor vegetation management (including tree cutting) increase the risk of cross-country faults (CCFs) and high-impedance fault (HIF) syndrome in these regions. Recognizing and classifying CCFs associated with HIF syndrome is the most challenging part of the project. This study extracted signal characteristics associated with CCF and HIF syndrome using the Tunable Q Wavelet Transform (TQWT). An adaptive tunable Q-factor wavelet transform (TQWT) based feature-extraction approach for CCHIF fault signals with high impact, short response period, and broad resonance frequency bandwidth was presented. In the first part, the time–frequency distribution of the vibration signal is used to determine the distinctive frequency range. Adaptive optimal matching of the impact characteristic components in the vibration signal was achieved by optimizing the number of decomposition layers, quality factor, and redundancy of TQWT based on the characteristic frequency band. In the last, the TQWT inverse transform was utilized to recreate the best sub-band to boost its weak impact characteristics. The effectiveness of the approach is confirmed by simulation and experimental findings in signal processing. The best decomposition level for signature features that can be extracted has been decided by Minimum Description length (MDL). The IEEE 39-bus system is used to test the suggested approach with reactor switching and the Ferranti effect. [ABSTRACT FROM AUTHOR]

Grid faults are found to be one of the major issues in renewable energy systems, particularly in wind energy conversion systems (WECS) connected to the grid via back-to-back (BTB) converters. Under such faulty grid conditions, the system requires an effective regulation of the active (P) and reactive (Q) power to accomplish low voltage ride through (LVRT) operation in accordance with the grid codes. In this paper, an improved finite-control-set model predictive control (FCS-MPC) scheme is proposed for a PMSG based WECS to achieve LVRT ability under symmetrical and asymmetrical grid faults, including mitigation of DC-link voltage fluctuation. With proposed predictive control, optimized switching states for cost function minimization with weighing factor (WF) selection guidelines are established for robust BTB converter control and reduced cross-coupling amid P and Q during transient conditions. Besides, grid voltage support is provided by grid side inverter control to inject reactive power during voltage dips. The effectiveness of the FCS-MPC method is compared with the conventional proportional-integral (PI) controller in case of symmetrical and asymmetrical grid faults. The simulation and experimental results endorse the superiority of the developed FCS-MPC scheme to diminish the fault effect quickly with lower overshoot and better damping performance than the traditional controller. [ABSTRACT FROM AUTHOR]

In recent years, shipborne emissions have become a growing environmental threat. The International Maritime Organization has implemented various rules and regulations to resolve this concern. The Ship Energy Efficiency Management Plan, Energy Efficiency Design Index, and Energy Efficiency Operational Indicator are examples of guidelines that increase energy efficiency and reduce shipborne emissions. The main engine shaft power (MESP) and fuel consumption (FC) are the critical components used in ship energy efficiency calculations. Errors in ship energy efficiency calculation methodologies are also caused by misinterpretation of these values. This study aims to predict the MESP and FC of a container ship with the help of data-driven methodologies utilizing actual voyage data to assist in the calculation process of the ship's energy efficiency indexes appropriately. The algorithms' prediction success was measured using the RMSE, MAE, and R2 error metrics. When the simulation results were analyzed, the Deep Neural Network and Bayes algorithms predicted MESP best with 0.000001 and 0.000002 RMSE, 0.000987 and 0.000991 MAE, and 0.999999 R2, respectively, while the Multiple-Linear Regression and Kernel Ridge algorithms estimated FC best with 0.000208 and 0.000216 RMSE, 0.001375 and 0.001471 MAE, and 0.999999 R2, respectively. [ABSTRACT FROM AUTHOR]

Presents an implementation of a stochastic Extended Kalman Filter algorithm, which provides optimal estimates of interconnected network states for power systems in which some or all measurements are delayed. Problem statement and formulation; Test results and discussion; Conclusion.

One of the common power quality (PQ) problems in transmission and distribution systems is the voltage sag that affects the sensitive loads. Losses and problems caused by the voltage sag in the power system can be reduced by correctly determining the relative location of the voltage sag. This paper proposes a novel algorithm to classify voltage sag relative location and fault type, which is the main root cause of voltage sag, based on the actual voltage and current data before and during the voltage sag. The performance of the algorithm is investigated by performing a numerical simulation utilizing MATLAB/Simulink. Moreover, the proposed algorithm is integrated into the power quality monitoring system (PQMS) of the real distribution system and tested. The results show that the performance of the proposed method is satisfactory. [ABSTRACT FROM AUTHOR]

Zero-emission transportation is currently a public priority, especially in big cities. For this reason, the use of electric vehicles (EVs) is receiving much attention. To facilitate the adoption of EVs, a proper charging infrastructure together with energy management is essential. This article proposes a design guideline for a direct current (DC) charging station with bipolar properties. A bipolar system can convert a two-wire system into three wires in a microgrid system with a neutral line. The configuration of the bipolar system supports different loads; therefore, the unbalanced operation is inherent to the system. The proposed bipolar DC charging station (CS) has a three-level balancing converter that reduces the step-down effort chargers. Moreover, this paper proposes the continuous-control-set model predictive control (CCS-MPC)-based balancing strategy that allows the handling of different output loads while keeping the neutral-line voltage efficiently regulated with improved dynamic performance compared to a traditional controller. Stability and parameter robustness analyses are also performed for the control parameter selection. To ensure the performance of the proposed method, both simulation and experimental results are presented and compared with those obtained from the traditional methods. [ABSTRACT FROM AUTHOR]

Smart grid plays a vital role in energy management systems. It helps to mitigate the demand side management of electricity by managing the microgrid. In the modern era, the concept of hybrid microgrids emerged which helps the smart grid management of electricity. Additionally, the Internet of Things (IoT) technology is used to integrate the hybrid microgrid. Thus, various policies and topologies are employed to perform the task meticulously. Pakistan being an energy deficient country has recently introduced some new policies such as Energy Wheeling Policy (EWP), Energy Import Policy (EIP), and Net Metering/Distributed Generation Policy (NMP) to manage the electricity demand effectively. In addition, the Energy Efficiency and Conservation Act (EECA) has also been introduced. In this paper, we present the overview and impact of these policies in the context of the local energy market and modern information and communication mechanisms proposed for smart grids. These new policies primarily focus on energy demand–supply for various types of consumers such as the demand for bulk energy for industrial ventures and the distributed production by consumers. The EWP deals with obtaining power from remote areas within the country to ease the energy situation in populated load centers and the EIP highlights energy import guidelines from foreign countries. The NMP deals with the integration of renewable energy resources and EECA is more focused on the measures and standardization for energy efficiency and conservation. The benefits and challenges related to EWP, NMP, and EIP have also been discussed concerning the present energy crisis in Pakistan. The generalized lessons learned and comparison of a few aspects of these policies with some other countries are also presented. [ABSTRACT FROM AUTHOR]

This study measures the long‐term electric energy data of an electric vehicle (EV) charging station, and uses these field measurements to analyse and construct the load behaviour model of an EV charging station. According to the statistics of field measurements, the state of charge of EV battery pack at the start of charging and the number of EVs starting charging in each time interval can be modelled using Poisson distribution, Roulette wheel selection and uniform distribution. The load behaviour of an EV charging station can be modelled and analysed accordingly. To validate the accuracy of the proposed load behaviour model, a portion of field measurements is reserved for load behaviour model verification. The proposed load behaviour model can also be used to analyse the impacts of EV charging stations on distribution systems. Test results show that the load behaviour model proposed in this study has higher accuracy and the impacts of EV charging stations on distribution systems can be analysed more effectively and precisely. [ABSTRACT FROM AUTHOR]

In recent years, the usage potential of alternative energy sources has been gaining importance to increase the efficiency of ships within the scope of the obligations brought by international maritime regulations. The possibility of using alternative energy sources such as solar energy, wind energy, fuel cells, and waste heat recovery technologies on ships has been evaluated in the literature. Today, ships also have waste heat recovery systems as standard equipment for this purpose, and this method is suitable for thermoelectric generators that generate electricity from temperature differences on shipboards. This article aims to review the thermal technologies for the power generation of shipboards. By conducting a case study, an energy efficiency increase was obtained when functional areas were selected on a practical ship, and the effect of this efficiency increase on emissions was examined. As a result of the research, it was discovered that thermoelectric generators increased onboard energy efficiency and have significant potential for sustainability in the maritime sector. [ABSTRACT FROM AUTHOR]

In light of the reliable operation of renewable shipboard microgrids, this paper implements a fractional-order theory for flexible modeling for an accurate study of shipboard microgrids. Then, it introduces a novel variable structure control strategy based on a fractional-order reduced chatter nonlinear sliding mode. This strategy incorporates a time delay estimation and an optimization routine for parameter adjustments, aiming to achieve nearly time-optimal control performance and faster frequency accommodation. The proposed method exploits the benefits of fractional order modeling, reduced chatter sliding mode, and variable structure approaches. While the adapted reduced chatter strategy may decrease convergence speed, the variable structure strategy compensates for this by accelerating settling speed. These features, along with continuous, soft, and limited control signals, make the proposed method suitable for the challenging conditions of low inertia, high dynamics, uncertainty, and a noisy environment in nonlinear renewable shipboard microgrids. The Lyapunov stability proof and simulation results demonstrate the proposed method's fast, high accuracy, and reliable performance. Furthermore, the validation process, which involves comparisons with conventional sliding-mode strategies, fractional-order proportional-integral-derivative controllers, and experimental test results using the Speedgoat real-time target machine in conjunction with Simulink real-time, serves to further establish the superiority of the proposed approach. • Introduces a novel approach using fractional-order theory for a unique variable structure control strategy tailored for shipboard microgrids. • Presents a cutting-edge control strategy based on fractional-order chatter-free nonlinear sliding mode for nearly time-optimal control performance. • Exploits the advantages of fractional order modeling, chatter-free sliding mode, and variable structure approaches to tackle challenges faced by renewable shipboard microgrids. • Mitigates the convergence speed reduction caused by chatter free solution using continuous, soft variable structure, and limited control signals. [ABSTRACT FROM AUTHOR]

- In recent years, the aviation industry has witnessed a substantial integration of power electronics technology within Aircraft Microgrids (AMs). Consequently, the extension of electrical wiring networks has expanded, resulting in heightened intricacies within these systems. Therefore, the identification and location of faults in wiring networks have become an important topic in AMs to guarantee the safety of the electrical power systems. Time Domain Reflectometry (TDR) is widely used to locate and recognize electric wire faults. However, soft fault location on complex electrical networks using TDR is perplexing due to its weak effect on the reflected signal. Moreover, the existence of noise in the environment can worsen the TDR's performance. In this paper, a new approach based on TDR, along with the Subtractive Correlation Method (SCM) and Neural Network (NN), is proposed. The TDR response of the complex wiring network is determined using a newly proposed model based on the Finite Difference Time Domain (FDTD) method. The validity of the proposed model is established through experimentation including two distinct cable types also the introduced model notably enhances computational efficiency, a fact substantiated by our experimental findings and an extensive benchmarking against recent publications. These evaluations collectively underscore a significant reduction in computational time. Then, the reflected signal undergoes processing through SCM, a technique employed to amplify the subtle influence of the soft fault in two scenarios: one accompanied by noise and the other noise-free. Furthermore, NN is used to handle the inverse problem of localizing and characterizing the soft faults by their exact resistance values. Even within noisy environments, the proposed methodology excels in accurately locating and characterizing soft faults with a high degree of precision, all in real-time diagnostic scenarios. • Novel FDTD-based model for determining the TDR response of intricate wiring networks. • Empirically validated model enhancing computational efficiency and reducing time. • SCM approach amplifies subtle soft fault impacts, even in noisy environments. • Neural Networks excel in precisely localizing and characterizing soft faults by resistance values. • Real-time diagnostic capability for pinpointing and characterizing soft faults with exceptional precision. [ABSTRACT FROM AUTHOR]

For many offshore activities, including offshore oil and gas exploration and offshore wind farm construction, it is essential to keep the position and heading of the vessel stable. The dynamic positioning system is a progressive technology, which is extensively used in shipping and other maritime structures. To maintain the vessels or platforms from displacement, its thrusters are used automatically to control and stabilize the position and heading of vessels in sea state disturbances. The theory of dynamic positioning has been studied and developed in terms of control techniques to achieve greater accuracy and reduce ship movement caused by environmental disturbance for more than 30 years. This paper reviews the control strategies and architecture of the DPS in marine vessels. In addition, it suggests possible control principles and makes a comparison between the advantages and disadvantages of existing literature. Some details for future research on DP control challenges are discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes a cost-effective compensator to suppress harmonics and compensate the power factor of all-electric shipboard power systems (SPSs). This compensator, which is based on a fixed capacitor-thyristor controlled reactor (FC-TCR), behaves as a low-pass filter and therefore can reject both low and high-order harmonics. Moreover, the FC-TCR compensator is featured by the low switching losses; hence, it can effectively be implemented for low and medium voltage applications. The design of the filter is detailed via equivalent lossy circuits, which exhibit the mechanism of the harmonic mitigation. Furthermore, theoretical analyses and mathematical developments are suggested to enhance the filtering performance. Besides, details of the Fixed-Point iteration technique which is applied to extract the firing angle of the TCR are conducted. A practical SPS is selected to ensure and demonstrate the performance of proposed methodology via thorough simulations under MATLAB/Simulink environment. The obtained results verify the theoretical analyses and confirm the effectiveness of proposed solution. [ABSTRACT FROM AUTHOR]

The penetration of renewable energy is gradually increasing. Therefore, power system flexibility, which is required to maintain system security and to cope with renewable generation uncertainty, becomes more important. Various technologies, such as flexible generators, demand management, energy storage, network reconfiguration, and even efficient system operations, are capable of improving power system flexibility. Nevertheless, among them, flexible generation resources can provide a direct way to enhance the power system flexibility. This article first applies the fuzzy analytic hierarchy process to calculate the flexibility index of generation resources. Then, the process of unit scheduling is implemented under various operation scenarios to investigate the relationship between the generation flexibility and the cost of unit scheduling. Finally, the required flexibility and the corresponding capacity of flexible generators under a specified penetration of renewable power generation are investigated under different operation scenarios. [ABSTRACT FROM AUTHOR]

The energy consumption of major equipment in residential and industrial facilities can be minimized through a variety of cost-effective energy-saving measures. Most saving strategies are economically viable where several algorithms can be employed to reduce energy consumption to reduce costs to a considerable extent. Machine learning (ML) is one of these techniques. A review of recent research efforts concerning the application of ML strategies to energy conservation and management problems is presented in this study. In addition, ML approaches and strategies for energy-saving problems, management, technologies, and control methods have been discussed. A comprehensive review of all available publications is also used to make observations about past considerations. As a result, it has been concluded that ML is capable of solving a wide range of decision and management problems within a short period of time with minimal energy consumption. In addition, ML perspectives have been viewed from the perspective of emerging communication technologies, instruments, and cyber-physical systems (CPSs), along with the advancement of ultra-durable and energy-efficient Internet-of-Things (IoT) based communication sensors technology. Moreover, a comprehensive review of recent developments in ML algorithms is also included, including safe reinforcement learning (RL), Deep RL, path integral control for RL, and others not previously. Lastly, critical ML considerations such as emergency and remedial measures, integrity protection, fusion with existing robust controls, and combining preventive and emergent measures have been discussed. The implementation of recently applied ML, RL, and IoT strategies for energy management, conservation, and resilient operation is clarified in this paper. The proposed review highlights the advantages and drawbacks of the recent energy conservation strategies. Finally, the perspective solutions have been clarified to cope with the world direction for zero energy buildings. • A comprehensive review of AI techniques in energy applications has been presented. • Empirical analysis of the energy management and conservation methods. • Describes the ML's and IoT's role in energy control and how to implement it. • Explains the challenges of demand-side data pre-processing of machine learning. • Offers possible directions for future research in the resilient operation of smart grids. [ABSTRACT FROM AUTHOR]

This paper discusses electrical distribution for refrigerated containers (reefers) in port terminals, characterized as parks of uniform distributed loads. Power systems of uniform distributed loads need configurations with modularity whenever possible, to ensure an easier installation, operation, and maintenance with significant cost reductions. This paper shows what has been the practice at ports in the past to provide Low Voltage (LV) supply to reefers from medium voltage (MV)/LV substations to cluster of reefer outlets panel with group of outdoor receptacles, used to connect power supply cord to each reefer. In the new method of power distribution system for the reefers, it is suggested to use a main MV underground distribution and portable containerized MV/LV transformer substations with close coupled LV distribution panel including reefer outlets. This potable power supply unit can be installed inside the reefer racks to supply locally a modular LV distribution to the reefers. This new method of supplying power to reefer racks has benefits over the past practice. It can offer a relevant flexibility for expansions and endorses development of new fitting components. [ABSTRACT FROM AUTHOR]

Power quality (PQ) is becoming more and more critical issue in shipboard microgrid systems (SMGs). Especially, the impact of voltage unbalance combined with harmonic distortions on the SMG behavior has not been fully investigated. In this paper, simple PQ assessment models and a series of controlled experiments are proposed and carried out in a real ship under sea-going conditions. The ship experimental results are presented and discussed considering nonlinear bow thruster load and high power ballast pump loads under unbalanced and harmonic voltage conditions. In addition, the analysis of bow thruster current harmonic surges during the ballast pump start-up is presented. Furthermore, the voltage/current distortions of a working generator, bow thruster and pump loads are analyzed. The paper provides a valuable analysis for coping with PQ issues in the SMG. [ABSTRACT FROM AUTHOR]

This work studies the power quality impacts of electric transportation charging including electric buses (EBs) and electric vehicles (EVs) on distribution systems. The stochastic harmonic models for EBs and EVs and the stochastic models for their usage scenarios are built utilising the measured charging data. Based on these models, a power quality analysis method considering the charging uncertainties of EBs and EVs is proposed in this study and then their impacts on distribution systems are investigated. The Monte Carlo simulation is integrated into the proposed method to study the under voltage, overcurrent, voltage unbalance, transformer overload, harmonic current, voltage etc. caused by the stochastic charging of EBs and EVs. An actual distribution system acquired from Taiwan Power Company is taken as an example to validate the practicability of the proposed method. The test results of the proposed stochastic model are compared with those of the conservative model. [ABSTRACT FROM AUTHOR]

This paper analyzes crane power supply, typical distribution schemes in typical container terminals, the different system grounding techniques, and their impact on the service continuity of cranes. On the primary- and secondary-medium voltage (MV) distribution systems, provided by loop configuration, service continuity can be achieved also by TN-systems, with automatic disconnection of supply, due to the power source redundancy. The MV supplying system of a crane (lines of tertiary distribution, devices, machinery) constitutes an equipment under control EUC that has to be guaranteed to achieve or maintain a safe and integer state in case of fault events. On crane MV power supply lines with radial structure, the possibility to ensure service continuity consists in choosing an IT-system with high-resistance grounding (HRG). In fact, the faulted line can stay on service after a ground fault during the short time necessary to maintain the service of the faulted crane and contemporary to try in solving the fault or to remove the same crane. [ABSTRACT FROM AUTHOR]

This paper deals with the relevance of analyzing the necessary development and of proposing a plan for research and remodeling the electrical infrastructures of port facilities. Good energy management principles, as well as electrical distribution architecture have a vital impact on performance of the installed system throughout its life cycle. The ports are the interface of maritime transport and are integrated in the surrounding land. They are required to arrange their electrical power distribution system, possibly in microgrids, that is, as a “utility” system, appropriate and adequate even to power the ship from shore. Harbors must have an energy master plan and their areas have to be considered as a unique customer. The energy management of a port area may be a great business opportunity for the port authority, which until now was not, involving different stakeholders who may benefit from service, including the same power utility company that benefits from the optimization and control of the energy flows. [ABSTRACT FROM AUTHOR]

• Investigating and revealing potential risks of poor energy quality for shipboard microgrids. • Providing a clear view of the importance of selecting the accurate algorithms for analyzing the quality of energy and delivering a comparative study. • Proposing a developed algorithm, which is an offline-based energy quality analyzing technique developed for the short-term protective action stage to assess the energy quality of shipboard microgrids. • Proposing an enhanced algorithm, which is an online-based energy quality assessing technique, Which is very suitable for the long-term preventive action stage. Retrofitting of shipboard microgrids is receiving much attention nowadays due to the flexibility it offers to adapt existing ships with rapid market variations to move towards all-electric ships (A-ESs). This modernity mainly relies on incorporating the power electronics converters that unfortunately draw a large number of harmonics, which affect the energy quality and threaten the system stability and crew/passengers safety. The contribution of this paper lies in proposing two developed open-loop algorithms to assess the harmonics distortion of A-ESs without relying on signal periodicity. The first algorithm is an offline-based analyzing technique developed for the short-term protective action stage, which incorporates the eigenvalue solution inside the short-time fast Fourier transform (ST-FFT) to adapt its window size. Consequently, this algorithm can provide a comprehensive harmonics analysis with a fast transient response even under large system frequency drifts. The second algorithm is an online-based assessing technique, which is very suitable for the long-term preventive action stage to provide accurate harmonics distortion assessment with the fast transient response and efficient computation burden. This approach relies on cascading three moving average filters (MAFs) with particular window sizes to filter and estimate the mean value inside the discrete Fourier transform and the true RMS blocks without the need of frequency information. Hence, it results in enhancing the harmonics rejection capability of the algorithm even under the existence of non-characteristic harmonics and frequency drifts. Simulation and experimental results are provided to validate the efficacy of the proposed algorithms and the results are compared with traditional methods. [ABSTRACT FROM AUTHOR]