ABSTRACT. Benefits of dc grid in avoiding dc/ac energy transform and reactive power consumption, and development of power semiconductors techniques push the trend of medium voltage (MV) dc network applications, e.g., onshore and offshore connection grids of renewables, MVdc electric ship, extreme fast charging station, and traction. The modular multi-level converter (MMC) is suitable to be used in these MVdc applications. In order to satisfy the requirements in various future MVdc applications, in this paper, the design concerns of the MMC, and grid faults handling techniques in the MMC-fed MVdc grid are studied as well.

ABSTRACT. Different DC/DC converter configurations are proposed in order to enhance power quality, improve power conversion efficiency, reliability and reduce size and complexity of these converters. For a better understanding of these converter topologies, operating in a residential standalone DC microgrid, this paper proposes a comparative study between two non-isolated converters working in boost mode, for a DC microgrid system composed of photovoltaic and wind sources, storage device, EV charger and residential local loads. The first converter is a conventional boost converter and the second one a Zeta converter. Both converters behave as Constant Power Loads (CPL). Main simulation results are given and discussed to show the performances of both topologies. Simulations were performed using PSIM software.

ABSTRACT. In this study, a robust control method of a serial multicellular inverter is suggested. This particular hybrid system represents a combination of three switching cells interconnected via two flying capacitors. These continuous and discrete variables confer a hybrid dynamical behavior which induces difficult control problems. To tackle these problems, a comparison between two different approachs has been done. First, we propose the conventional PWM control with triangular carriers. Then, a new control concept based on Petri Nets was developed and tested. This methodology shows the versatility of controlling the flying capacitor voltages and the output current. Provided simulation results certify the efficiency and the robustness of Petri Nets formalism to control this type of converters.

ABSTRACT. Chaotic PWM control is a new emergent method for suppressing conducted electromagnetic interference (EMI) generated by the dc-dc power converter. It effectively suppresses the peaky harmonics by spreading it all around the central frequency in the desired wide frequency band. Thus the EMI spectrum is smoothed and flattened with a reduced EMI noise level. The current paper presents a chaotic Pulse Position Modulation (PPM) technique based on the Logistic map. It is generated digitally through a dsPIC microcontroller. Then, it is applied to a boost converter to reduce the conducted EMI generated within. Looking for accuracy, an electromagnetic (EM) prototype of the boost converter was developed using LTspice in order to analyze the EMI reduction level. Finally, spectrum simulations were carried out. The chaotic PPM was benchmarked to traditional PWM for the boost converter. Simulations show a significant reduction of EMI with a flattened EMI spectrum.

ABSTRACT. A novel solution to the voltage control problem of a dc/dc boost converter feeding an arbitrary constant power load (CPL) is developed. Particularly, as CPLs exhibit negative incremental resistance, a fact that in combination with the nonlinear nature of a converter/CPL system creates ad hoc stability problems, a nonlinear control design is proposed with main purposes: i) to be effective on regulating the output voltage regardless of the power absorbed, ii) to be easily implemented as a feedback loop from measurable states and outputs. In the feedback loop the measurable current at the power load side is fed back diminishing the need to apply any adaptation or other complicated mechanism for estimating the power absorbed by the CPL. Hence, the proposed controller analysis is based on the complete closed-loop nonlinear model instead of using standard linearized techniques and asymptotic stability is proven by applying suitable Lyapunov methods. This design approach extends the controller validity in a wide range while in practice it can be easily realized. The stable and good performance of the controller is finally evaluated by simulations taken with various CPL levels.

ABSTRACT. A LED (Light Emitting Diode) driver operating under a DC input voltage and driving a series of high power LEDs, is presented in this paper. Different topologies of LED driver feeding a constant current into a LED load and their operation principles are analyzed and discussed in detail. Then, a laboratory prototypes of constant-current LED drivers based on DC-DC buck converter with full dimming capability is designed, implemented, and tested. Experimental results show good agreement with simulation results.

ABSTRACT. The integration of electric vehicles into distribution grids poses new challenges to distribution system operators: while maintaining a valid grid operation state with only limited control and information about electric vehicles’ charging processes, customers should be impaired as little as possible by demand side management measures. In order to tackle these challenges in a combined approach, a demand side management algorithm with focus on limited charging process information is implemented. Different levels of available information about charging processes are taken into account and missing information is estimated based on customer behavior statistics. A simulation framework is set up to investigate the effects of various scenarios of penetration and controllability levels. Simulations are run using the model of an existing low voltage grid. Results show that the load profiles generated based on the aforementioned estimations help reducing invalid grid states caused by unsupervised charging processes. Moreover, the algorithm reduces the amount of violations of the targeted threshold values exponentially with the number of controllable charging stations. Incorporating additional information about loading processes improves the management system by reducing both, the amount of uncharged energy and the number of unfinished loading processes.

ABSTRACT. Integration of renewable energy sources accompanied with decommission of fossil fueled power plants inherently results in lack of power system flexibility. In turn, this reduced flexibility calls for additional balancing services. In parallel to this, the process of transport sector electrification is in place and the large fleets of electric vehicles (EVs) could prove to be one of the solutions for increased power system flexibility needs. If managed adequately, EVs could be able to provide the missing balancing services. In this paper, a model of EV day-ahead market and frequency containment reserve bidding is defined in order to asses the potential challenges that could arise during such service provision. Special attention is given to the EV battery state of energy, since the batteries are energy-limited resources and specific issues may arise both at individual EV and fleet level.

ABSTRACT. This paper overviews a theoretical and practical design issue related to the wireless recharge system. It verifies a mathematical method for identifying the transfer time for the wireless transfer system using a functional prototype and concerning the speed movement of the receiver face the transmitter. The accurate analysis tries to define the static and dynamic model relation and parameters. The influence of the speed value in this system is depicted inside the given model. The main objective of this paper is to express the dynamic model of the wireless charger system and defines the related parameters. The results try to prove the relationship between the outputted power and the car's speed.

ABSTRACT. The low voltage (LV) Network has become more complex due to the addition of loads like Electric Vehicles (EVs) and generation from renewable energy sources. These additions will result in power quality issues arising from excess supply or load imbalances. As LV networks and power systems were not designed with these entities in mind, scalable and flexible mitigation strategies will be needed to tackle these problems. This paper presents a new implementation framework to address this challenge. The framework consists of a Multi-Agent Control System (MAS) to coordinate the various independent entities (agents) and a Thévenin Equivalent Impedance (TEI) based estimator to measure real time load imbalances to determine optimal currents in real time and adjust supply/demand optimally to minimize losses. The MAS and TEI device will be verified on an IEEE European Low Voltage Test Feeder. Open DSS will be used to model the network, JADE and MatLab will be used to model the MAS and its functions respectively while Python will be used to model the TEI component.

ABSTRACT. The transport sector continues to be the greatest contributor to the alarming emission levels. In fact, today more than ever, people favor the use of passenger vehicles over public transport to avoid contact with coronavirus. Carbon savings made across the sectors during the global lockdown to control the spread of the novel COVID-19 virus are therefore at a great threat. This necessitates the need for sustainable transition to an ultra-low carbon transportation system. Although, electric vehicles enablement continues to aid with transition, the sustainability of the fuel poses greater risks for pollution shifting. In this paper an DC microgrid EV charging solution powered by renewables is explored through MATLAB and HOMER simulation. A realistic approximation to carpark special constraints is calculated and a solar PV system in both S-shape and M-shape configurations is modelled. The analysis for efficient space utilisation is based on sun path data and weather conditions in the city of Leeds for a constant peak load of 10 EVs. As well as, an alternative in the form of a small wind turbine is compared with photovoltaics for a single charging station.

ABSTRACT. Commercial electric vehicle (EV) chargers aim to provide a better charging solution compared to residential chargers. However, even with low penetration, they add considerable stress on the electric grid and can cause severe consequences. One of the possible solutions is to coordinate the charging process and even allow discharging. In this paper, the optimal day-ahead operation of several smart EV parking lots is considered in an active distribution network. The aim of the proposed approach is to maximize the daily profit through admission and scheduling of the best suitable requests to the proper EV charger in the parking lot. In addition, bidirectional power flow is considered to minimize stress on the grid during peak hours. Moreover, the proposed approach considers a practical scenario with different types of chargers installed in a parking lot. Thus, one of the approach tasks is to assign the EVs to the proper charger, which is the main contribution of this work. Simulation results on a typical distribution system demonstrate the effectiveness of the proposed approach.

ABSTRACT. Recent work on transmission usage charging has offered compelling new perspectives on how current flows in electrical power systems. One new insight is that a certain component of branch current flows solely to serve loads in the system, whereas another component arises because of voltage mismatches between generator buses. These circulating currents affect active power losses and branch congestion, and thus may be of renewed interest to system operators. This paper presents novel power system visualizations which better show the separate load-serving and circulating aspects of a network. A key insight that emerges is the dual role of the branches in a system: they carry both load serving and circulating currents, in heterogeneous proportions. This perspective permits new branch centrality metrics to be proposed, which separately gauge a branch’s role in serving these distinct functions.

ABSTRACT. This paper proposes new tools for predicting and visualising the plausible near term shifts in branch loading that may arise due to output fluctuations from renewable generators. These tools are proposed to enhance situational awareness for control room operators, by providing early warnings of where bottlenecks may manifest in a transmission system. For predicting plausible branch loading shifts, a linear optimal power flow formulation is presented which uses a novel objective function to characterise the maximum loading a branch could be exposed to in the short term. This analysis therefore identifies which branches could become overloaded due to shifts in output from volatile generators. Equivalently, these branches can be seen as congestion bottlenecks which may cause curtailment of renewable generation. To allow the system operator to maintain awareness of such potentialities, these congestable branches are highlighted on a system diagram which is drawn to explicitly portray the electrical distance between components in the network.

ABSTRACT. Power traders and system operators need to balance the uncertain generation of renewable energy sources by adapting the dispatch of conventional power plants. This poses a challenge to voltage control in power system operation. Accordingly, this paper presents a method to determine voltage magnitude probability densities which are integrated into an optimal reactive power flow to consider an uncertain active power generation. First, the probability densities are determined by Monte Carlo simulations including a unit commitment problem to derive the dispatch of conventional power plants. Second, uncertainty restrictions are used to create soft constraints for the optimal reactive power flow, which mitigates the risk of voltage limit violations. By adapting the slack costs of the soft constraints, the consideration of uncertainties can be prioritized in relation to other objectives, such as the reduction of active power losses or reactive power costs.

ABSTRACT. This paper proposes a novel method for clustering nodes based on prevailing power flow conditions within a power grid. To this end, first, the network’s active power flow state is modelled as a directed acyclic graph. This digraph explicitly represents where power is flowing and this can help in monitoring and analysing system vulnerabilities. The directed acyclic graph representation also allows easy identification of those buses that solely provide or absorb active power: these are pure source and sink nodes, respectively. An iterative path-finding procedure is applied to every node in the system,to enumerate the sources that is fed by, and the downstream sinks towards which it forwards power. The novel clustering algorithm is then applied, to group together those nodes which share the same set of reachable sources and sinks. This novel clustering methodology is proposed in the first instance as a tool to boost the situational awareness of control room operators by better summarising aggregate power flow dispositions in large grids. The proposed methodology is applied to two sample grids, and an analogy to river systems is articulated, applying such notions as tributaries, distributaries and the central mainstream to electrical networks.

ABSTRACT. In the research field of power system operation it is common to approximate the considered period of time based on discretized power flow patterns. However, the efficient utilization of the transmission grid infrastructure demands an increasing amount of congestion management measures, such as topology changes via switching measures or adjustments of phase shifting transformers. Transmission system operators must arrange these measures in a decreasing period of time to take account of an increasingly volatile power system. In order to analyze the trajectory between a current and a future grid state, a 2-stage simulation model is proposed. By applying the model to a test system, it is shown that the transition path is highly dependent on the chosen operational sequence, which is defined as the chronological order of operational measures. The mean loading of specific overhead lines during an exemplary transition path differs by up to 50 % depending on the chosen operational sequence.

ABSTRACT. The business models for peer-to-peer electricity trading are emerging but number of challenges still have to be solved to allow large-scale deployment. The aim of this paper is to investigate effects of producer’s offering prices on power flows within a distribution grid where peer-to-peer electricity trading is simulated. The peer-to-peer electricity trading is simulated as a near real-time auction-based local electricity market and applied on the modified IEEE European Low Voltage Test Feeder. That way, the effects on peak load requirements and local energy balance are studied. The results point out that peer-to-peer electricity trading can stimulate active participation of prosumers, which can lead to better local demand/supply balancing and reduction of peak demand from the upstream grid.

ABSTRACT. The aim of this study is the investigation of the effects of parameters involved in the characterization of radiating sources in the near field (NF). The main issue is to deal with structures of power electronic systems that are generally excited by non-sinusoidal signals. The identification is based on the electromagnetic time reversal (EMTR) technique. Indeed, the electromagnetic field was synthesized analytically using expressions of equivalent dipoles radiation in time domain (TD). The effects of several parameters on sources characterization, including the height of measurement, time reversal mirror (MRT), potential sources network, and the measuring probe were evaluated. Several simulation tests have been applied to this set of parameters to determine their simultaneous effect on the identification of radiated emissions of a power electronic structure. Based on this parametric study, a compromise between the accuracy of the obtained equivalent model and an acceptable computing time is determined and demonstrated to provide an efficient reconstruction.

ABSTRACT. This paper presents detailed modeling principles of a typical Inductive Power Transfer (IPT) module using the Matlab/Simulink software. The presented model, with an AC-AC Direct Converter is implemented by four MOSFET switches followed by a resonance LC circuit and has been designed with user-friendly blocks of the Simulink block library. The model provide better understanding of the output current characteristic of an AC-AC Direct Converter model under resonance frequency conditions. The main objective of this paper work is the development of technological knowledge, based on Matlab/Simulink programming language, related to Typical Inductive Power Transfer (IPT) System

ABSTRACT. Thepaperisdevotedtoa3D-FEAbasedcomparison between different topologies of claw-pole alternators, namely: conventional claw-pole alternator (CPA), inter-pole PM claw-pole alternator (IPM-HECPA) and hybrid-excited brushless claw-pole alternator (HEBCPA). The study is initiated by a description of the studied topologies and an analysis of their rotor-stator main linkage flux. Then, a special attention is paid to their on-load features which is predicted by 3D-finite element analysis (FEA), with emphasis on the armature voltage and current waveforms, theirharmoniccontentsaswellastheiroutputcurrentwaveform. In order to highlight the effects of the inter-pole PMs and the removing of the brush-ring system, the investigation of the onload features is started by the conventional CPA with a single DC-excitation in the rotor, then it is extended to the hybrid excited topologies. 

ABSTRACT. Over the years, the need to save energy and efficiently manage its consumption becomes increasingly imperative. This paper reports on the development of a novel application for handling diverse energy consumption issues in large passenger and cruise ships. Our overall approach is based on a comprehensive agent-based simulation model, which takes into account spatial data concerning a ship’s decks and position of energy consuming facilities, as well as data concerning the ship’s passengers and their behavior during the operation of the vessel. The proposed application may predict energy consumption for a particular vessel and passenger group and accordingly facilitate informed decision making on energy saving matters.

ABSTRACT. An accurate and fast model is essential for implementation of the model predictive control (MPC) in building management systems to reduce the load on electric grid without sacrificing occupant comfort. In this paper, an opensource emulator model (made available on GitHub) has been developed for a Danish university teaching building to be applied in the MPC toolchain BOBTEST within the IBPSA project 1 [1]. The model is calibrated and realistic occupancy is introduced based on data measured by meters installed in the building. Simulation and sensitivity analysis performed on controllers and electricity-consuming devices helped to improve the emulator implementation and make it BOBTEST-ready. Results indicate that (1) the model is physically realistic in terms of electric load and thermal comfort estimation and (2) a new control/actuation setup considerably improves simulation time.

ABSTRACT. Energy is required now more than ever due to population growth, industrialization and modernization. Hydroelectric power is a comparatively cheap, reliable, economical, and renewable source of energy that can be generated without toxic waste and considerably lower greenhouse gases emissions as compared to fossil fuel energy plants. Run off river hydro which is hydro energy in a “small” scale provides electricity to small communities by converting hydro energy into electrical energy if properly harnessed. In this research work, assessment of run of river hydropower potential within river Kaduna, mathematical model will be developed using MATLAB R2018a to know the size of turbine to be used. Simulation of the model for a long-term forecast of the river will be done on the MATLAB environment, based on the power generated the turbine type and sizing will be determined.

ABSTRACT. The future power/energy systems will be characterised by blurred boundaries between transmission and distribution system, by mix of wide range of electricity generating technologies (conventional hydro, thermal, nuclear and power electronic interfaced stochastic and intermittent renewable generation), responsive and highly flexible, typically power electronics interfaced, demand and storage with significant temporal and spatial uncertainty, proliferation of power electronics (HVDC, FACTS devices and new types of load devices) and significantly higher reliance on the use of measurement data including global (Wide Area Monitoring) signals for system identification, characterization and control and Information and Communication Technology embedded within the power system network and its components. The key characteristic of such a complex system, if it is only one to be picked, would certainly be prolifereation of power electronic devices in different shapes and forms and for different purposes. This will increase controllability and observability of the system but may as a trade off result in different/unexpected dynamic behaviour of the system and possibly, under some circumstances, deterioration of some aspects of its performance. This presentation identifies some of the challenges associated with operation and control of power systems with significant pentetration of power electronics interfaced generation and loads and approaches to identify, model and overcome them.

ABSTRACT. This talk is about the microgrid concept, so how can we produce, store and consume energy locally and the relationship with our life philosophies concern that to change outside world, we need to change from inside out. The talk give some examples of how these technologies are impacting our daily lives with solar PV in our rooftops, electrical vehicles in our garages and home energy storage systems. The way we are also conceiving energy generation outside, in the big grid, is now taking many ideas from the microgrid concept, and more than ever, grid forming concepts are starting to be proposed in large PV and windfarms – some examples of projects will be explained. The same way, many examples and technologies for smart homes will be shown, integrating the microgrid technology in our daily lives all together IoT electronic devices, wearables and e-health systems, including smart devices to practice mindfulness.

ABSTRACT. Energy systems can have a different degree of complexity depending on where they “occupy within the set of facilities; in the room houses for example, there are components, such as: lamps, contacts and switchers, etc. On the other hand, in more complex installations the components can be industrial, such as: distribution boards or electrical networks that must analyze their behavior and optimal condition in their operation. The conference will showcase the fundamental concepts of an analysis and the technology used today to safeguard the facilities and the lives of the staff operating them. In addition, the fashion theme of the implementation of ADMS solutions or Advanced Distribution Management System and the relationship of how the commercial sector and industry seek to fulfill what is being immersed in Latin American countries that is the ” Grid Code”. The result of such solutions will allow to share how companies are aimed at monitoring in real time the energy expenditure with studies carried out on-line using specialized software for continuous improvement and implement a combined planning and operation solution to manage, control, visualize and optimize the electricity distribution grid.

ABSTRACT. The structure of the Low Voltage distribution networks is not always accurately known by the Distribution System Operators, especially with the significant meteorological variations observed in recent years and the growth of decentralized PV production sources. In this paper a probabilistic Load Flow algorithm has been developed for radial Low Voltage network considering the line resistance distribution as an uncertainty depending on the temperature. The single-phase network model is therefore associated to the temperature variation in the network deployment area. The Load demand and the PV production generally used in classical Load Flow calculation are computed using Smart Meter data with a quarter of an hour resolution time. Both power values are considered to be time varying. Either the resistance value or the network to client exchanged power are randomly selected at each iteration using a Monte Carlo method. Both annual and seasonal dependencies of the line resistance have been implemented in the developed Probabilistic Load Flow. The simulation results have shown that integrating the resistance distribution in a seasonal probabilistic tool can impact the collected reliability indices up to 10.4% depending on the season. In a context of upgrading the Low Voltage electrical network knowledge by the Distribution System Operator, and with an accordance to the requirements of the EN50160 standard, this tool can be presented as an efficient algorithm for quantifying the impact of the line resistance statistical distribution on a Probabilistic Load Flow computation.

ABSTRACT. The development of ultra-low carbon emission electric vehicles (EVs) has been grown rapidly over the last years in response to the large share of greenhouse gas emissions contributed by the transportation sector. One of the main issues among EV drivers is range anxiety, which mainly results from the long charging battery durations. DC fast charging, the latest charging technology, aims to shorten charging duration; however, the success of e-mobility will be also related to the capacity of the distribution network to integrate the new EVs and their chargers. Specifically, the integration of EVs and DC fast chargers will increase the peak demand and may pose significant challenges for MV and LV distribution networks if adequate control measures are not implemented. This paper introduces a topology for the modelling and connection of a DC fast charger on a real MV/LV distribution network and ensures that the network operates within acceptable limits and that consumers connected to it are minimally affected. Simulation results show that DC fast chargers stress the LV distribution network by causing grid congestions; however, local voltage control measures and a vehicle-to-grid technology can improve some of the grid-side challenges.

ABSTRACT. This paper proposes a robust model thatoptimizes the joint cooperation between the distribution systemoperator (DSO) and the electric vehicle aggregators (EVAs) considering the forecasting uncertainties. The developed cooperation model considers electric vehicles (EVs) in avehicle-to-grid operation, fuel-based distributed generators, and wind generators. The purpose of the proposed model is to optimize the operational planning that simultaneously minimizes the DSO’s energy cost and maximizes the revenue of each EVA. The proposed model is applied to a 14-bus distribution system to verify its effectiveness and robustness.

ABSTRACT. Reliability improvement is a fundamental aspect of modern power distribution systems and smart grids. The optimal distribution network reconfiguration (DNR) has been proven an effective and economic way to improve system’s reliability. This paper overcomes the nonlinearity of the DNR problem constraints and thus presents a convex model for optimal DNR with the objective of 1) reliability indices improvement, and 2) power loss minimization. The proposed second-order cone programming based method is tested on a 69-bus distribution system examining different scenarios for the weighting coefficients of the objective function’s terms. The obtained results demonstrate the effectiveness and usefulness of the proposed optimization model.

ABSTRACT. In recent years, the exploitation of weatherdependent renewable energy sources, available at distributed local sites, has led to the increased volatility of electrical energy supply. In order to compensate for the intermittent nature of renewable energy sources and remedy to possible imbalance problems on the national grids, the users of the electricity system are required to reduce interactions with the grid and increase the self-consumption of energy. Accordingly, prosumers equipped with local generation and storage systems are encouraged to join the electricity community groups, as they can produce, store and share energy with the other members of the community. The proper sizing of storage systems is essential in this context. This paper presents an optimal management model based on the energy sharing among the prosumers of a community, with the aim of evaluating the impact of the storage systems’ sizes on the energy self-consumption and on the cost savings that can be achieved.

ABSTRACT. This paper studies the optimal control by implementing the quadratic linear regulator (LQR) for a doubly fed induction generator (DFIG) attached to wind turbine system. The advantages of using the LQR regulator is to obtain, firstly, a speed regulation allowing a maximum extraction of the power of the wind turbine and secondly, a regulation of the DC bus voltage so that the machine maintain a unit power factor for the converter-side mains and pulls magnetizing current from the stator. Essentially, standard LQR regulator provides proportional gains. This makes it possible to study the stability of the system.

ABSTRACT. Dense turbine deployments with close separation distances is a good option to effectively exploit a site with good wind resource and hence, generate large scale wind energy. This nature of turbine deployments should be done with caution considering the wake interactions and possible increase in turbine loads. This study presents turbulence intensity variations with freestream wind speed, as the turbine wakes travel down a large array of turbines for different turbine-to-turbine separation distances in hexagonal farm layouts. The study couples Park and Law’s modification of the popular Jensen’s wake model, with Frandsen’s simplified “wake turbulence” model for its modelling and analysis. The results show that larger turbine-to-turbine separation distances in the longitudinal direction are likely to promote a quicker saturation of turbulence intensities downstream compared to smaller turbine-to-turbine distances. Hence, a need to simultaneously optimize hub velocity and turbulence intensity levels at each turbine, for large wind farm arrays with such dense deployments; which leads to smaller turbine-to-turbine spacing.

ABSTRACT. The aim of this paper is to show the effectiveness of using a PMSG in offshore wind turbines to obtain reliable and efficient systems. A comprehensive detailed dynamic model and control strategy of a variable speed offshore wind turbine is described. The wind turbine is linked to the electrical grid by means of a back to back converter. The core of the converter is composed of two similar inverters linked via a DC-link bus. The PMSG side converter performs maximum power extraction from the wind by combining a Field-oriented control (FOC) strategy and a maximum power point tracker (MPPT) controller. While, the grid side converter ensures an efficient grid connection employing a voltage oriented control (VOC) strategy. Simulation results show the effectiveness of the proposed control under rigorous wind conditions.

ABSTRACT. The Brazilian northeast wind resource makes the region attractive for the construction of wind generation projects and consequently brings the need for investments in new transmission lines to supply this increase in generation demand. This paper presents the case study of the increased ampacity of a 230 kV overhead transmission line in the state of Pernambuco, responsible for the generation flow of a wind farm under different wind speeds. The study analyzes the impact of wind speed variations on the power transmission capacity. Analyzes of the wind atlas of the state of Pernambuco and information from the National Institute of Meteorology database are performed. The results showed that the increase in wind speed up to 4.0 m / s results in the increase of wind farm installed capacity, with approximately 70% generation gains.

ABSTRACT. Wind energy as source of electricity has grown rapidly in the recent years. Consequently, a great variety of research on wind turbines impact on environment is necessary. It is worth to mention that notably the Small Wind Turbines gain on importance. This is due to low assembly and maintenance costs and increasingly restrictive large-sized wind turbines erection law. Safety system for a wind turbine is a crucial part of a secure energy source. In this paper the design and implementation of low-cost safety system for Small Wind Turbine is presented.

ABSTRACT. For the successful energy transition, the Modular Multilevel Converter (MMC) serves as an attractive solution for HVDC power transmission. Within this paper, the partial integration of additional energy storage elements into the underlying structure of the converter is presented. By extending a certain proportion of the submodules to form energy storage modules, the resulting Energy-Storage MMC is capable of storing or releasing an additional portion of its rated power on the AC-side without the need to adjust the DC power flow. The design of this topology and the necessary modifications for the control structure are studied. The property of storing or releasing additional power during normal operation enables the converter to provide grid-supportive functions. The ES-MMC concept is validated by conducting appropriate dynamic simulations in MATLAB Simulink. For this purpose, its participation in the frequency containment process and in power oscillation damping is examined in the Kundur two-area test system.

ABSTRACT. Declining equivalent inertia caused by the massive integration of converter-based technologies can increase the risk of stability problems in the future power system. Control of HVDC systems as Virtual Synchronous Machines (VSMs) for providing emulated inertia is a promising countermeasure against this development. However, low inertia converter-dominated power systems are raising new challenges for stability analysis. Thus, new numerical techniques and tools are needed for efficient and accurate analysis of small- and large-signal stability issues in complex power systems with different kinds of generation units, converter systems and control loops that can experience potential interactions, internally or with the network. Gear's method with a variable time step, offers the possibility to obtain fast and flexible procedures for large-signal stability analysis. Additionally, it can make stability analysis efficient by combining the small-signal and large-signal analysis into the same process. This paper will show how the stability of a power system with a VSM-based HVDC link can be evaluated by the method and presents an approach for simultaneous small- and large-signal stability assessment. 

ABSTRACT. The fast deployment of renewable energy sources requires an increasing amount of frequency regulation reserves in the electric power system. Residential thermostatically controlled loads are ideal candidates to provide such services due to their thermal inertia, large energy buffers and high power ratings. However, the coordinated control of a large number of appliances represents a large-scale control problem with high computational requirements. To alleviate these needs, several aggregate modelling and control strategies have been developed in the recent literature. This paper compares two aggregate models for frequency regulation with electric water heaters used for domestic hot water: a generalized battery model and a set of representative tracer devices obtained with the cross-entropy method. Under realistic simulation assumptions, it is shown that, whereas the generalized battery model better describes the behavior of a group of electric water heaters, the tracers provide a better prediction of the available flexibility for reserves provision.

ABSTRACT. Frequency of power supply system needs to be kept constant or fixed irrespective of the varying changes in load demand in order to ensure the well-being of power generating equipment and delivery of good quality power at the demand side. The primary duty of Load Frequency Control (LFC) is to maintain the frequency deviation within prescribed tolerance limit, while most existing LFC schemes do not work usually in the best required manner in practice and may not also fulfill a desired response and performance parameters. This paper presents an enhanced digital PD controller for LFC of UAE power system based on a systematic method using Root Locus method. The controller is designed in continuous-mode and discretized in implementation with optimum selected sampling period to circumvent any degradation of dynamic performance and instability that may arise from inappropriate sampling period. The proposed system is a single area for reheat thermal system and the proposed model has taken into account the role of load disturbance in the analysis and control of frequency deviation. The proposed digital controller is simple and effective and ensures that the overall system performance is in line with the desired response and transient requirements and shows remarkable improvement in the system performance

ABSTRACT. Modular Multilevel Converters for High Voltage Direct Current (MMC_HVDC) is a hopeful technology for future smart grid and offshore applications. This modular configuration allows to an output of almost an ideal sinusoidal voltage which permits to prevent the harmonics injected into the power system; therefore, there is no need to use large filters in the system. Furthermore, it allows for supporting a high voltage rating. Thus, it is appropriated for High Voltage Direct Current (HVDC) transmission systems applications. This paper studies the operation of a point to point MMC-HVDC system simulated with its associated loop controller.

ABSTRACT. This article aims to shed light on an essential approach to maximize output efficiency and optimize power consumption of a wind turbine by highlighting the components and control of the electric system. The primary component of the system is the permanent magnet synchronous generator. The mentioned generator is selected based on the Cp-lambda curve of the turbine, which determines the desired rated power and rotational speed of the generator. The wind turbine generator is promptly followed by power electronics stages of rectifier –to convert the generator’s AC output voltage DC voltage- and consequently DC/DC boost converter to augment the output voltage to 60V. The Maximum power point tracking algorithm extracts the maximum output power of the turbine by means of the current controller. Additionally, a pitch mechanism is implemented to control the wind turbine once it passes the rated wind speed. Sensors such as rotational velocity, temperature and current sensors are employed to perform data acquisition for the controllers and to enable the user to have full control of the wind turbine. The wind turbine system has been simulated on SIMULINK and the power results were compared to the output of the real hardware setup.

ABSTRACT. PMSG based small wind turbines are more and more used in modern electric generation systems. Two main topologies are commonly used for the generator side converter of these turbines. The first topology is based on a three-phase diode rectifier, an uncontrolled DC-link and a boost converter. The second topology is based on a two levels voltage source converter. Despite the fact that the first topology is the most used solution, there is a lack of research works that accurately present the related model and control. This paper presents a continuous model of a PMSG assisted by a three-phase diode rectifier, an uncontrolled DC-link and a boost converter. Also, it presents the design of an efficient speed controller that ensures robustness against rough changes of the wind input power. Several simulation results are presented and discussed to demonstrate the accuracy of the developed models and the robustness of the designed speed controller.

ABSTRACT. Nowadays energy is considered one of the biggest challenges facing humanity, in fact, based on the growth trends the world will inevitably be resource and carbon-constrained, such is the case we need to supply the world’s growing energy demand with clean, safe, affordable and scalable. In this paper, we focus on the optimization of hybrid (solar-wind) grid-connected renewable energy systems in administrative building. The objective of the study is to minimize the total net present cost of generation and cost of energy using HOMER Pro software. Sensitivity analysis is also carried out that helps to assess the effect of uncertainty or changes within the variables and finding the most optimal solution for hybrid energy system.

ABSTRACT. In this paper, a method for estimating the winding Eddy Loss based on an improved harmonic loss factor for transformers under harmonic conditions is presented. The method considers the skin depth of penetration of the field at higher harmonic orders, leading to a greater degree an accurate estimation of the winding Eddy losses under harmonic conditions.

ABSTRACT. This study tackles a procedure for designing and optimizing the chord and twist angle of the blade using MATLAB optimization toolbox to maximize the power coefficient (CP) then to maximize the annual energy production (AEP). The process leading to optimization includes selection suitable airfoils, placing the airfoils along the blade radius, splining between the specified airfoils. The performance of the blade design is evaluated using a MATLAB code that uses the blade element momentum theory (BEM) and its modifications to get the results. The blades of the turbine and their aerodynamic efficiency are considered vital to the small wind turbine (SWT) efficiency and therefore vital to its spread in the market. The study achieved maximum power coefficient of 0.3647 and energy of 361.8 kWh/year for a blade radius of 70 cm, a hub radius of 10 cm and wind speed of 9 m/s with Weibull distribution parameters A= 4.5 and k= 2 and the used airfoils are S835 and S834. The results showed a direct and fast approach for designing an efficient SWT and this makes the SWT an economic solution that eases the transition towards a more sustainable world.

ABSTRACT. The power system planning task is a combinatorial optimization problem. The objective function minimizes the economic costs subject to a set of technical and operational constraints. Meta-heuristics are often used as optimization strategies to find solutions to this problem by combining switching, line reinforcement or new line measures. Common heuristics are genetic algorithm (GA), particle swarm optimization (PSO), hill climbing (HC), iterated local search (ILS) or newer methods such as grey wolf optimizer (GWO) or fireworks algorithm (FWA). In this paper, we compare these algorithms within the same framework. We test each algorithm on 8 different test grids ranging from 73 to 9421 buses. For each grid and algorithm, we start 50 runs with a maximum run time of 1 hour. The results show that the performance of an algorithm depends on the initial grid state, grid size and amount of measures. The ILS method is very robust in most cases. In the larger test grids, more exploratory heuristics, e.g., GA and PSO, find solutions in shorter run times.

ABSTRACT. the main objective of this paper is to optimize the parameters of sliding mode controller for DC motor. Ant Colony Optimization (ACO) algorithms is used to obtain optimal parameters of Sliding Mode Controller (SMC), which is highly robust to the parameters variations. A model of DC motor is developed and simulated using MATLAB/SIMULINK by introducing external uncertainties and disturbances. The proposed speed control design uses gains generated by the Ant Colony Optimization algorithm.

ABSTRACT. Micro-siting, also known as Wind Farm Layout Optimization (WFLO), is useful in finding the optimal layout of wind turbines, enabling them to harvest the maximum amount of power. The wake effect that the turbines in wind farms produce on each other causes a reduction in wind velocity, thus altering the overall output power. The wake effect should be minimized in order to maximize the output power. Arbitrary layouts could lead to poor effectiveness in the output power. The main objectives of this study are to quantify the power losses due to layouts and to clearly assess and consider the results of the wake effect model. Jensen’s model is used with a fixed number of turbines to demonstrate the importance of the wake effect in wind farming. The direction and wind speed of the selected site are considered when determining the power loss due to turbine layout. This study shows the importance of optimizing the wind farm layout using the wake effect model to obtain maximum output power.

ABSTRACT. In this paper, the Harmony Search Algorithm (HSA) is proposed to estimate the optimal parameters of a hybrid active power filter (HAPF). Mathematical modeling of an industrial plant with linear and nonlinear loads combined with HAPF is developed. Four cases of study have been simulated using MATLAB/Simulink software to evaluate the effective performance of the HSA in obtaining the optimal parameters under clean and distorted voltage source environment. The performance of the proposed HSA is assessed in terms of the voltage and current total harmonic distortion indices (VTHD) and ITHD, respectively. The performance of the proposed HSA is compared with that of the Fortran Feasible Sequential Quadratic Programing (FFSQP) and L-SHADE optimization algorithms. The simulation results show that the performance of the proposed HSA has superseded the performance of the previous mentioned algorithms.

ABSTRACT. As the load characteristic of the distribution system varies over time, the network topology also changes from one point of consumption to another. The methodology addressed in this study consists of alternating distribution network switches for different load points on the daily consumption curve, two scenarios are investigated, in order to obtain an optimal reconfiguration of the distribution system with the aim of both reduce power losses and improve the voltage profile. To deal with, an improved PSO methodology coupled with MATPOWER toolbox was applied on the IEEE 33-bus radial distribution network and the obtained results show the effectiveness of reconfiguration procedure for enhancing the test system performance.

ABSTRACT. Cloud computing has become the bedrock of new, emerging smart technology. It has numerous benefits that encourage small, medium and large enterprises to use other technology through the internet. Despite the benefits of cloud technology, the challenge of the high power consumption rate it incurs as its leverages its promised attributes remains. This paper used mobile agent technology to solve the complexity problem in the data centre system, which happens to be the backbone of cloud technology. The mobile agent was embedded to both servers and switches to regulate their activities and then shut down underutilised components. Mobile agent(Java agent) is the first of its kind used on a cloud network. Our proposed approach saved a significant amount of energy and also improved the entire system performance during runtime.

ABSTRACT. This paper presents a new integrated RF energy harvesting system using a rectifier with reconfigurable stages. The design replaces the diode-connected transistors used in conventional RF-DC rectifiers with diode-emulated transistors for minimizing conduction losses. In addition, a voltage feedback loop is employed to regulate the output voltage at the main load. Extra available power is provided to a secondary storage unit (supercapacitor). The system is implemented in a 130nm CMOS technology, and circuit simulations show that the proposed design achieves a peak power conversion efficiency (PCE) of 29% at 0dBm input power, and a load regulation of 10mV.

ABSTRACT. The development of new renewable sources of clean electric energy (EE) is an urgent scientific and technical task. To solve it, comprehensive measures are carried out using methods and ways of converting various types of energy into electrical energy. At the same time, special attention is paid to autonomous decentralized sources of green energy, namely, devices that can be installed in places with a high foot traffic density. EE is being generated thanks to pedestrians moving on such devices. The aim of the work is to study the process of generating renewable energy by an energy-generating platform (EP) based on a multiplier with spur gears, depending on the number and connection scheme of stepper motors to the electric machine unit of the EP. Experimental studies of the electric power generation process have been carried out, depending on the number and connection scheme of stepper motors (SM) to its electric machine unit. Such a platform has compact overall dimensions and it is intended to be installed both indoors and outdoors, in places with high foot traffic. To conduct experimental research, a prototype of the EP with an electric machine unit was developed. The analysis of the conducted experimental studies and the subsequent processing of their results made it possible to determine that the use of two SMs in the EP electric machine unit increases the value of the generated electricity by ~44%. When performing one step on the EP, the installation generates approximately 1.11W of electricity. The connection of two SMs increases the value of the generated electricity by 1.69 times (in direct motion) and 1.38 times (in reverse motion). Knowing the EP potential capabilities and the passing people number, it is possible to calculate the EE value which the EP can generate in a certain time of work, which allows you to determine the required number of such devices at the facility to provide it with the green EE fully or partially.

ABSTRACT. During the last few years, the management of Olive Mill Wastewater is extensively investigated. Solar greenhouse drying can be the efficient first step to obtain a sludge which can be a potentially recoverable resource. The purpose of this work is to perform a comparison between horizontal and modified even span greenhouse dryers designated to dry Olive Mill Wastewater. The dryers were modeled and simulated using COMSOL Multiphysics. For both dryers, the temperature, the velocity, as well as, the total evaporated mass profiles were presented and discussed. The efficiency of the modified even span greenhouse solar dryer compared to the horizontal one was highlighted.

ABSTRACT. Renewable energy sources like the sun have great potential to change the energy sector. Photovoltaic arrays are required to harness this energy; however, obtaining maximum power from the arrays has always been a challenge. Several authors have proposed different maximum power tracking (MPPT) algorithms. This paper presents a comparative study between the Incremental Conductance and Perturb & Observe MPPT to find the most efficient and effective algorithm at any irradiance and temperature. Simulation and experiment were conducted with results analyzed and compared. From the analysis, the general observation emerges that the Incremental conductance algorithm is the best performing algorithm.

ABSTRACT. Several models have been suggested for the simulation of Hybrid Renewable Energy systems (HRES) among them HOMER, SAM, HOGA and INSEL. This paper compares simulation performed using HOMER and the new ECOS model for a village in Turkana district in Kenya, which has excellent direct normal irradiation (DNI) of about 1800kWh/m2/year. The ECOS model is a new software recently developed by students of Jomo Kenyatta University of science and Technology. The metrics used for comparison are the Levelised cost of electricity, net present value represented by cash flows, externalities (environmental, social and economic factors) and the energy generated. The novel contribution of this paper is the inclusion of the social, health and environmental impacts of Solar PV which is not done by other software like HOMER. The LCOE results from ECOS model are slightly higher than those obtained from the HOMER simulation

ABSTRACT. Farmers spend a lot on conventional pumping methods to provide fresh water to their livestock. This paper deals with the design of an automatic pumping system for pastoral farming in rural areas. To replace the current conventional methods, this system is powered with PV panels which reduces cost because the sun cannot be tariffed. Most pumps must be manually controlled hence the objective is to supply the water to the designated location via automatically controlled system without human interventions by implementing a suitable automation method. This will be achieved by simulations through Microcontroller ATMEGA16 type programmed in embedded C language. This system involves solar modules and water level sensors. These sensors are located inside the water tank to detect the amount of water and then inform the farmer. Thus, from a remote location, the farmer can communicate with the pump for water level control in the tank via GSM module. If the water level reaches a level below the predetermined level, the pump should pump in water without farmer’s notification to prevent motor run dry problems and so that water requirements are met. Consequently, reduction in environmental impacts as solar energy is clean and efficient, and thus effective use of water and electricity.

ABSTRACT. Six-Switch current source inverter (CSI) is a promising unidirectional DC-AC power conversion topology deduced from the reversed structure of the very sparse matrix rectifier. This latter is a single-stage boost-type inverter suitable for grid-connected applications as it provides active power injection from renewable energy sources into the AC grid. This paper investigates the performance of three different soft-switching strategies for three-phase six-switch grid-connected CSI. These strategies are analyzed in terms of the number of switching transitions, DC-link current ripple, average global value of the conduction and switching power losses, as well as, the quality of the injected grid-currents. The proposed evaluation is based on both, theoretical analysis and computer simulations. A comparative study is, commonly, established and the optimum modulation strategies are selected.

ABSTRACT. Green energy technologies like solar photovoltaic generation are gaining increased interest from environmentally conscious public entities. They require little maintenance, and it’s easy to increase the plant size to meet a growing energy demand. With this project, the solution is premised on the integration of solar photovoltaic based renewable energy source with the main supply grid of the building. The inverted ac power from the plant is fed to the critical load during the day and the design should maintain a constant supply of hybrid renewable energy supply of PV-grid or PV-battery, when the embedded generator is no longer sufficient.

ABSTRACT. Large scale solar photo voltaic plants are being developed and implemented at rapid rates and others are being set up to occupy large tracts of land running to millions of acres across the globe. The cascaded environmental impacts of such huge installations are not well addressed in both literature and in the famous techno-economic modelling tools such as HOMER, SAM, INSEL and TRNSYS. This study provides a full cost approach for determining the Levelized cost of Electricity (LCOE). The study incorporates all the costs incurred during generation and operation including the externality costs that have been traditionally omitted by other models. This has been aided by the use of a new software called the ECOS model developed by students of the Jomo Kenyatta University of Science and Technology. The study carries out sizing of Solar PV for Lodwar and the resultant metrics such as LCOE when externalities are included. The novel contribution of this paper is the incorporation of the environmental impacts of Solar PV which has not done by other software tools like HOMER.

ABSTRACT. This paper introduces a framework to analyse cascading effects in the interdependent power and information and communications technology (ICT) networks that form the power system. The framework supports integration of interdependencies between the power grid and various ICT systems, but also of domain-specific intra-dependencies of the different subsystems. A simple system is modelled as example and three failure scenarios are presented to showcase the applicability of the framework for the investigation of cascading failures and to studying the effects of augmentations to the networks.

ABSTRACT. The globalization and rapid industrialization of any country is a function of availability of electricity in desired quality and quantity. Nigeria and Egypt are the most populated countries in West and North Africa respectively with incredible energy resources both renewable and non-renewable. Yet, the former is highly energy deficient when compared to the later. In recent time, the appropriate authorities have tried earnestly to reform the sector with the intent to improve the unpalatable situation through the liberalization of the vertically integrated structure of the power industries. In this paper, therefore, the review of the electricity tariff plan as well as justification of the present charge on electricity consumption is addressed. Although, the Multi Year Tariff Order (MYTO) and Open Brackets (OB) system presently adopted in Nigeria and Egypt for energy charge might appear effective from the operator’s side and the better path to follow but it may be classified as ineffective from the consuming end. However, with the right policies, regulatory framework, standards, interventions and appropriate legislation by the former, the latter is expected to embrace the methodological approach provided the elements considered in tariff setting viz; forex, price of gas, revenue collection which precludes the willingness to Pay (WTP) for energy, the Life Cycle Cost (LCC) of power plant, the level of demand, size and capacity of generation are within conformity. This therefore could guarantee a cost-reflective tariff thereby providing a more competitive environment for investors and the nation at large.

ABSTRACT. The energy system decarbonization and decentralization require coordination schemes for distributed generations and flexibilities. One coordination approach is local energy markets for trading energy among local producers and consumers. The resulting local coordination leads to the questions of how the interaction between local and wholesale markets will be designed and of how the introduction of local energy markets influences the wholesale market system. Therefore, this paper proposes a bottom-up modeling method for local markets within a pan- European wholesale market model. Furthermore, an aggregation-disaggregation method for local markets is developed to reduce computational effort. A case study for local markets in Germany shows the computational advantages of the aggregation-disaggregation method. Preliminary results indicate the impact of different interaction designs between local and wholesale markets on the wholesale market and show the need for further research.

ABSTRACT. The successful realization of the climate goals agreed upon in the European Union’s COP21 commitments makes a fundamental change of the European energy system necessary. In particular, for a reduction of greenhouse gas emissions over 80%, the use of renewable energies must be increased not only in the electricity sector but also across all energy sectors, especially in heat and mobility. Furthermore, a progressive integration of renewable energies increases the risk of congestions in the transmission grid and makes network expansion necessary. An efficient planning for future energy systems must comprise the coupling of energy sectors as well as interdependencies of generation and transmission grid infrastructure. However, in traditional energy system planning, these aspects are considered as decoupled. Therefore, the project PlaMES develops an approach for integrated planning of multi-energy systems on a European scale. This paper aims at analyzing the model requirements and describing the modeling approach.

ABSTRACT. Conventional power systems are transitioning to smart grids for remote control, reduced losses and auto correction of system faults. An energy management system for smart grids based on renewable sources is critical due to the intermittent nature of output power from these sources and variability of the load demands, which yield voltage and frequency fluctuations. This study analyses the superiority of smart grids based on power electronic transformers. P-F droop control method and Q-V droop method have been used for frequency and voltage rectification respectively. MATLAB simulations were run and the results show the hybridized smart grid has better stability as compared to stand-alone systems. The optimization method used is hybrid particle swarm and grey wolf due to its faster convergence performance and fast implementation process. The study finds that implementation of the management strategy modeled would result in 100% load supply and hence stability of the power system.