Showing papers by "Giuseppe Buja published in 2018"

A Simple Active and Reactive Power Control for Applications of Single-Phase Electric Springs

Abstract: Aiming at effective power management in microgrids with high penetration of renewable energy sources (RESs), this paper proposes a simple power control for the so-called second-generation, single-phase electric springs (ES-2), which overcomes the shortcomings of the existing ES control methods. By the proposed control, the unpredictable power generated from RESs is divided into two parts, i.e., the one absorbed by the ES-2 that still varies and the other injected into the grid that is controllable by a simple and accurate signal manipulation that works both at steady-state and during RES transients. It is believed that such a control is suitable for the distributed power generation, especially at domestic homes. In this paper, the proposed control is supported by a theoretical background. Its effectiveness is at first validated by simulations and then by experiments. To this purpose, a typical RES application is considered, and an experimental setup is arranged, built up around an ES-2 implementing the proposed control. Testing of the setup is carried out in three steps and proves not only the smooth operation of the ES-2 itself, but also its capability in running the application properly.

Emerging Multiport Electrical Machines and Systems: Past Developments, Current Challenges, and Future Prospects

Abstract: Distinct from the conventional machines with only one electrical and one mechanical port, electrical machines featuring multiple electrical/mechanical ports (the so-called multiport electrical machines) provide a compact, flexible, and highly efficient manner to convert and/or transfer energies among different ports. This paper attempts to make a comprehensive overview of the existing multiport topologies, from fundamental characteristics to advanced modeling, analysis, and control, with particular emphasis on the extensively investigated brushless doubly fed machines for highly reliable wind turbines and power split devices for hybrid electric vehicles. A qualitative review approach is mainly adopted, but strong efforts are also made to quantitatively highlight the electromagnetic and control performance. Research challenges are identified, and future trends are discussed.

Performance Comparison of the One-Element Resonant EV Wireless Battery Chargers

Abstract: The one-element resonant topologies of the wireless battery chargers (WBCs) for electric vehicles (EVs) are analyzed with the aim of giving both a thorough assessment and a comprehensive comparison of the performance of the topologies. The analysis is carried out in terms of the following performance indexes: efficiency versus power injected in the EV battery, power sizing factor of the supply inverter, power sizing factor of the transmitter and receiver coil set, current sizing factor of the supply inverter, and behavior under the extreme conditions of open- and short-circuited operation of the receiver. At first, the two topologies with series resonance of the receiver coil and series/parallel resonance of the transmitter coil are investigated and their performance indexes are formulated. Then, the investigation is extended to the two topologies with parallel resonance of the receiver coil and series/parallel resonance of the transmitter coil. Afterward, merits and limits of the topologies are discussed. Measurements obtained from series–series and series–parallel WBC setups are given that corroborate the theoretical findings.

Analysis and design of DD coupler for dynamic wireless charging of electric vehicles

Abstract: In dynamic wireless charging (DWC) of battery-powered electric vehicles (BEVs), inductive power transfer takes place between two coils, one buried into the road and the other one installed onboard ...

The State of the Art of Topologies for Electric Springs

Abstract: This paper aims to review the state of the art in topologies for electric springs (ESs) and their suitability for different applications in distributed power systems with sufficient power generation from renewable energy sources, especially at domestic households. Owing to the fact that there exist many kind of ESs, a comprehensive overview of single-phase ESs sequenced as ES-1, ES-2, ES-3 and other forms, three-phase ESs (TPESs) sequenced as TPES-1, TPES-2 etc., and direct current ES (DCES) sequenced as DCES-1, DCES-2, PVES is conducted. The originalities, advantages and disadvantages of each ES topology version are analyzed to propose its most suitable application. Besides, comparisons between ESs and traditional flexible alternating current transmission (FACTS) devices are addressed. Finally, conclusions and possible future research trends are pointed out.

The State of the Art of the Control Strategies for Single-Phase Electric Springs

Abstract: The concept of electric springs (ESs) has been proposed as a new solution for stabilizing power grid fed by intermittent renewable energy sources. With a battery or active power source (DC, on the inside), the ESs can provide both active and reactive power compensations. So far, three typical topologies of single-phase ESs have been reported. Unlike traditional devices where power generation follows the load demand, the ESs are associated with non-critical loads form the so-called smart loads that transfer the fluctuated power to the non-critical loads, adaptively, according to the intermittent nature of power generation. After reviewing the main control strategies of single-phase ESs, the paper analyzes their advantages and disadvantages as well as their suitable applications. Comparisons among different control strategies on a specific topology version are implemented. Finally, conclusions and possible future trends are pointed out.

Transferred Power Leveling/Energy Maximization in Dynamic WPT Systems

Abstract: The paper deals with the design of the compensation network in the wireless power transfer systems (WPTSs) devoted to charging the electric vehicles (EVs) while cruising. An inconvenience of these systems, commonly termed dynamic WPTSs, is the large variation of the power transferred to the EVs due to the correspondingly large change of the mutual coupling between the pickup and the track coils during the EV motion. Many attempts have been done to level such a power by help of multi-element compensation networks. In this paper, a simple one-element compensation topology, namely the series-series one, is considered and the design is aimed at evaluating its power leveling capabilities by a suitable sizing of the track-side compensation capacitor. As an alternative, the objective is pursued of maximizing the transferred energy. Formulation of the analytics for the two objectives is presented and the results obtained on a study case are given. It is shown that the achievement of the two objectives leads for a somewhat different size of the compensation capacitor, depending on the length of the pickup compared to that of the track coils.

Dynamic EV Charging WPT System Control Based on Modulated Variable Laplace Transform

Abstract: The paper deals with the control of an LCL-compensated WPT system (WPTS) for the dynamic charging of electric vehicles (EVs) As it is well-known, the high working frequency of the WPTSs prevents their instantaneous control because of the fast processing that would be required for the controlled quantities, well beyond the capabilities of the modern microcomputers Therefore, the control of the WPTSs is carried out by acting on the envelopes of the controlled quantities on account of the fact that they have a sinusoidal waveform In this paper, the controlled quantities selected for the considered WPTS are the transmitting coil current and the DC-bus voltage at the receiving stage, and the input quantity is the supply inverter voltage The transfer functions (TFs) between their envelopes are at first computed by means of the Modulated Variable Laplace Transform method Then, the controllers of the WPTS control system are designed by help of the computed TFs At last, the performance of the arranged control system is tested by simulation

Application of Smart Transformer Load Control to mitigate Voltage Fluctuations in Medium Voltage Networks

Abstract: Penetration of renewable energy sources introduces variability in the electric power generation. It causes grid voltage fluctuations that adversely affect operation of critical loads. Mitigation of these fluctuations is traditionally achieved by compensating for the reactive power absorbed at the point of common coupling. In the paper, the Smart Transformer (ST) load control is applied to adjust the active power absorbed by the noncritical loads. In the paper, this application of ST load control is explicated showing its enforceability in the presence of distribution lines with resistive parameters of the same order as the reactive ones. Results obtained for a study case are also given that support the theoretical findings.

Emerging Multiport Electrical Machines and Systems—Part II

Abstract: The papers in this special section on emerging multiport electrical machines and systems is to provide an opportunity for researchers and engineers from academia and/or industry, to exchange their enlightening ideas on analysis, design, and control of such new machine breeds, to identify the challenges in practical applications and to present the state-of-the-art solutions. Distinct from the conventional electric machines with only one electrical and one mechanical port, electrical machines featuring multiple electrical/mechanical ports provide a highly efficient, compact, and flexible manner to convert and/or transfer energies among different ports. The additional electrical ports can be used to increase the power rating, enhance the fault-tolerant capability, and control the motion/power flow. The extended mechanical ports are commonly used to decouple the motion, speeds, and/or torque. The multiport feature opens a new era in traditional electric machinery and provides an effective approach to the application-oriented design of new energy conversion systems. Though relatively young, they have experienced rapid developments in terms of available topologies, analysis and design techniques, and control strategies in a wide range of applications, such as electric vehicle/hybrid electric vehicles, high power industrial drives, rail transportation, wind turbine systems, ac–dc microgrids, more electric aircrafts, and so on, during the past decades.

Dead-Beat Control Cooperating with State Observer for Single-Phase Electric Springs

Abstract: Aiming at improving the performance of the existing for single-phase electric springs (ESs), such as the fastness of the voltage stabilization and the mitigation of the voltage harmonics across the critical loads (CLs), the dead-beat control cooperating with state observer is proposed in this paper. First, the δ control is reviewed, outlining its features of regulation of the CL voltage while keeping the ES operation stable. After describing the operation of an ES in the continuous-time domain by the state-space technique, its discrete-time model is formulated using the zero-order-hold (ZOH) algorithm. Then, the control system for an ES is designed around the dead-beat control cooperating with a state observer and implementing the two typical compensation functions achievable with the δ control, namely the pure reactive power compensation and the power factor correction. Results obtained by simulation demonstrate that the control system is able to both properly drive an ES and to implement the two functions. The results also show that the proposed control system has the advantage of eliminating harmonic components in CL voltage when grid voltage distorts.