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Next Generation Inverters Equipped with Virtual Synchronous Compensators for Grid Services and Grid Support
Get PDFL'abstract è presente nell'allegato / the abstract is in the attachmen
Grid-Feeding Inverter with Simplified Virtual Synchronous Compensator Providing Grid Services and Grid Support
Get PDFThispaperproposestheenhancementofthecontrolof agrid-connectedinverterbyasimplifiedvirtualsynchronouscompensator (S-VSC) model working in parallel with the traditional inverter current control loops. The goal of the integration of this model into the inverter control scheme is to provide grid services, such as virtual inertia behavior, current harmonic compensation, aswellasreactivegridsupportduringfaults.TheS-VSCisonlyin charge of providing the aforementioned services, working, therefore, always at a low power level. On the other hand, the main power references are sent directly to the inverter control loops. This way, a more stable and damped operation of the inverter is obtained. The proposed structure has been implemented on a 15 kVA grid-connected inverter for experimental validation
Ricarica ultraveloce: sfide e opportunità
No full textLa ricarica ultraveloce delle auto
elettriche preoccupa i gestori della rete.
L'elevato e intermittente assorbimento
di potenza pone ardue sfide al sistema
elettrico. E se invece nascondesse
un'opportunità
Fast Simulator for the Estimation of Inverter DC-link Temperature in e-Drives Subjected to Highly Variable Working Cycles
No full textAccurate estimation of losses and operating temperatures is extremely important for the design of traction inverters and its validation for specific operating conditions. Although several methods are already available in the literature to estimate the semiconductor power losses, the power losses and temperature evaluation of inverter DC-link capacitors are less explored. Therefore, this paper presents a fast simulation model of traction eDrive to provide accurate estimation of DC-link loss and temeperature, as well as DC link voltage ripple evaluation. The proposed model is implemented in Simulink and consists of both a loss model based on loss maps and a circuital model to estimate the dc-link voltage ripple. This model is very fast and therefore it is very useful when the eDrive is subject to long and highly variable driving cycles. Moreover, the model accounts for the influence of the main parts of the powertrain and allows a proper verification of the selected DC link capacitor
Simple Active Damping Solution for Industrial Grid-Tied Inverters Using LCL Filters
Get PDFGrid-tied power inverters are typically interfaced with damped LC or LCL filters to limit the injection of switching harmonics. To minimize filter losses, the damping resistance of the filter is often reduced, resulting in poorly damped or unstable conditions at the resonant frequency. Therefore, different active damping solutions have been proposed in the literature to reduce passive elements while avoiding unstable conditions. However, most available solutions require additional current sensors or implement complex active damping algorithms. Moreover, the literature provides only partial guidelines to tune the active damping parameters. Therefore, this paper proposes a sensorless active damping solution based on a resonant current estimator and provides a straightforward tuning for its parameters. The proposed active damping method is experimentally tested on a three-phase, two-level 30 kVA inverter, thus demonstrating the validity of the presented approach
Transient Stability Improvement of Virtual Synchronous Generators under Current Limitation: The Benefits of Virtual Power Feedback
No full textExperimental Identification of Induction Machine Flux Maps for Traction Applications
Get PDFNowadays the permanent magnet machines are a widespread solution in the automotive field. However, the induction machine (IM) represents a valid solution as it is rare-earth free and does not have induced stator back-emf in case of inverter turn-off. Regardless of the machine type, identification procedures are needed for torque control calibration and for optimal machine utilization in terms of efficiency and maximum torque production under inverter current and voltage constraints. For synchronous machines, a common and consolidated practice is to obtain the machine flux maps (current-to-flux relationship) in the rotor (d,q) frame using calibrated Finite Element Analysis (FEA) or experimental procedures. However, to the best of the authors' knowledge, the literature does not report an experimental approach able to obtain the flux maps for IMs. Therefore, this paper proposes an experimental procedure to obtain the IM flux maps in (d,q) rotor flux frame for inverter supply and real operating conditions. In addition, the proposed procedure is able to obtain the parameters of the IM equivalent circuit with no need of additional tests. Experimental validation is provided for a 4-poles IM rated 10 kW, 200 Hz
A Detailed Analysis of the Electromagnetic Phenomena Observed During the Flux-Decay Test
Get PDFThe paper analyses in detail the physical
phenomena involved during the flux decay test used for the
rotor time constant determination. The analysis has been
performed on a 15 kW induction motor and the back e.m.f
transient has been critically analysed during its evolution,
finding a link between its time-by-time evolution and the
physical phenomena that happen in both the stator and the
rotor. In particular, the effects due to the lamination saturation,
the stator and rotor leakage inductances and the stator iron
losses have been associated to the transient evolution of the back
e.m.f.
Fault-ride-through Strategies for Modular Multilevel Shipboard Storage System
No full textIn waterborne applications, the up-to-date
objective is emissions reduction. The current effort to achieve
this target is oriented towards a complete electrification of the
maritime sector. The battery energy storage system plays a
crucial role in this area, the reliability and the continuity of
service of these battery systems are topics of remarkable
interest. This paper deals with the failures in multilevel modular
systems and the possible solutions to them. Every module is
composed of a battery pack and a bidirectional DC-DC
converter that regulates the electrical parameters of the battery
pack. The effects of the fault of the power converter are
investigated and fault-tolerant strategies in multilevel module
structures are proposed. Several simulation results are
presented to explore the control approach, for continuous power
conversion with acceptable quality and output current levels, to
be adopted after a fault event
The Compensator Approach: Solving the Transient Stability Issues of Virtual Synchronous Machines
Get PDFThe continuous integration of renewable energy sources (RES) into the grid through power electronics impacts the power system stability, posing new challenges for control techniques implemented on power converters. The virtual synchronous machine (VSM) represents a viable power converter control solution for the RES integration, providing natural grid support capability resulting from the emulation of the synchronous machine behavior. However, the VSM control faces transient stability issues under large voltage sags due to the significant acceleration of the virtual rotor. The literature reports numerous transient stability analyses, proposing different control solutions to improve the transient response of virtual synchronous generators (VSGs). However, they increase the complexity of the control algorithm, requiring additional tuning. Furthermore, they often mitigate rather than eliminate the transient stability issues. Therefore, this article provides a new perspective on VSM implementation, proposing the virtual synchronous compensator (VSC) concept as a straightforward and definitive solution to eliminate the VSM’s transient instability. The VSC maintains its synchronism under large and prolonged voltage sags, overcoming the transient stability issues implied by conventional VSG algorithms without additional control modules. The VSC’s transient response is verified theoretically and experimentally, proving the claimed benefits
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