The ongoing evolution of the power system towards a "SmartGrid" implies dominant role electronic converters, but poses strict requirements on their control strategies to preserve stability and controllability. In this perspective, definition decentralized schemes for converters that can provide grid support allow seamless transition between grid-connected or islanded operation is critical. Since these features already be provided by synchronous generators, concept Virtual Synchronous...

Over the last decade, frequency-droop-based control schemes have become preferred solution in microgrids dominated by power electronic converters. More recently, concept of virtual synchronous machines (VSMs) has emerged as an effective method for adding inertia to system through These two approaches been developed separate contexts, but present strong similarities. In fact, they are equivalent under certain conditions, demonstrated this letter. Analysis equivalence provides additional...

This paper analyzes the extent to which low voltage ride through (LVRT) capability of wind farms using squirrel cage generators can be enhanced by use a STATCOM, compared thyristor controlled static var compensator (SVC). The transient stability margin is proposed as indicator LVRT capability. A simplified analytical approach based on torque-slip characteristics first quantify effect STATCOM and SVC margin. Results from experiments with 7.5 kW induction machine emulating turbine are used...

The concept of Virtual Synchronous Machines (VSM) is emerging as an alternative approach for control power electronic converters operating in the system. One main motivation applying VSM-based to achieve a simple emulating inertia effect traditional synchronous machines. This paper provides comprehensive literature review on VSM and possible classification different schemes. In addition, small-signal response emulation characteristics proved be equivalent conventional droop-based standalone...

This paper presents a comparison of the small-signal stability properties for virtual synchronous machines (VSMs) with dynamic and quasi-stationary representation internal machine (SM) model. It is shown that electrical equations may introduce poorly damped oscillations when realistic stator impedance values high-power SMs are used. The implementation less sensitive to model, but depends on filtering measured d- q-axes components ac-side voltage avoid instability or oscillations....

Control structures containing cascaded loops are used in several applications for the stand-alone and parallel operation of three-phase power electronic converters. Potential interactions between these complex functional dependence controller parameters system dynamics prevent effective application classical tuning methods case converters operating with a low switching frequency. A approach guided by eigenvalue parametric sensitivities calculated from linearized model converter its control...

This paper presents a single-phase virtual synchronous machine (VSM) and its possible application for providing vehicle-to-grid (V2G) services from domestic battery chargers of electric vehicles (EVs). In VSM, the power converter is controlled to emulate inertia damping effect machine. Thus, VSM-based EV charger can contribute spinning reserve frequency regulation system. case grid outages, VSM seamlessly establish an islanded supply local loads onboard EV. order avoid influence on...

In this paper, a methodology is presented to identify and analyze interaction modes between converters in voltage-source converter multiterminal high-voltage direct current (VSC MTDC) systems. The absence of substantial level energy stored such power-electronics-based systems results fast system dynamics, governed by electromagnetic phenomena. Moreover, interactions are largely influenced the control parameters and, general, an priori identification based on associated time constants less...

This paper demonstrates how the range of stable power transfer in weak grids with voltage source converters (VSCs) can be extended by modifying grid synchronisation mechanism a conventional synchronous reference frame phase locked loop (PLL). By introducing an impedance‐conditioning term PLL, VSC control system virtually synchronised to stronger point counteract instability effects caused high impedance. To verify effectiveness proposed approach, maximum static capability and small‐signal...

Virtual Synchronous Machines (VSMs) have been introduced as a control concept for emulating the behavior of traditional synchronous machines with power electronic converters. This paper analyses VSM scheme where an outer loop inertia emulation provides references two cascaded voltage and current controllers. offers several advantages compared to alternative implementations. However, interactions between loops complex functional dependency system dynamics respect controller parameters...

This article discusses the general challenges of high-power battery charging in marine applications, with a focus on electric ferries that have tight schedules and short docking times. For such inductive wireless power transfer allows for safe fully automated operations better utilization time batteries. Battery ship applications requires higher levels single unit than what has been demonstrated public transportation systems like buses trams. The technical designing are discussed,...

State‐of‐the‐art time‐domain models of power cables account for the frequency dependency physical parameters to enable accurate transient simulations high‐voltage transmission schemes. Owing their formulation, these cannot be directly converted into a state‐space form as required small‐signal eigenvalue analysis. Thus, dc are commonly represented in direct current (HVDC) system stability studies by cascaded pi‐section equivalents that neglect frequency‐dependent effects. This study...

The concept of Virtual Synchronous Machines (VSMs) is emerging as a flexible approach for controlling power electronic converters in grid-connected well stand-alone or microgrid applications. Several VSM implementations have been proposed, with the emulation inertia and damping traditional Machine (SM) their common feature. This paper investigates implementation based on Voltage Source Converter (VSC), where virtual swing equation provides phase orientation cascaded voltage current...

This paper proposes a simple method for inherently frequency-adaptive virtual flux (VF) estimation intended voltage-sensor-less grid synchronization and control of voltage source converters. The characteristics are obtained by using second-order generalized integrator configured as quadrature signal generator (SOGI-QSG) with the frequency an explicit input variable. It is also shown how properties VF based on SOGI-QSGs can be utilized to achieve effective technique that integrates bandpass...

This paper presents a virtual flux-based method for voltage-sensor-less power control of voltage source converters under unbalanced grid conditions. The synchronization is achieved by flux estimation with inherent sequence separation in the stationary reference frame. estimated positive and negative (PNS) components are used as basis calculating current references corresponding to following objectives active reactive powers conditions: 1) balanced currents, 2) elimination double-frequency...

More electric aircraft (MEA) architectures consist of several subsystems, which must all comply with the settled safety requirements aerospace applications. Thus, achieving reliability and fault-tolerance represents main cornerstone when classifying different solutions. Hybrid (HEA) extends MEA concept by electrifying propulsive power as well auxiliary power, thereby pushing limits electrification. This paper gives an overview high-power electrical machine families their associated...

The dc-side dynamics of modular multilevel converters (MMCs) can be prone to poorly damped oscillations or stability problems when the second-harmonic components arm currents are mitigated by a circulating current suppression controller (CCSC). This paper demonstrates that source these is uncontrolled interaction and internally stored energy MMC, as resulting from CCSC. Stable operation improved performance MMC control system ensured introducing closed-loop current. presented analysis relies...

This paper investigates the operation of a current controlled Voltage Source Converter (VSC) under weak grid conditions caused by large impedance. Three different controller structures are investigated; conventional decoupled PI-controller in synchronously rotating reference frame, Proportional Resonant (PR) controllers stationary and phase hysteresis controllers. The control strategies studied simulation, results show how impedances can influence dynamic response system. It is further...

Gearboxes for wind turbines must ensure high reliability over a period of 20 years, withstanding cumulative and transient loads. One main challenge to this is represented by electromagnetic torque transients caused grid faults disturbances, which will result in significant stresses fatigue the gearbox. Possibilities limiting fixed-speed generators have not been previously reported. This paper presents technique torques during recovery after fault can be smoothed farm with induction directly...

This paper investigates the operation of space-vector-based hysteresis current control in synchronous reference frame (SRF) for grid-connected voltage source converters. The approach allows systematic application zero-voltage vectors and prevents high switching frequencies caused by phase interaction. average frequency can be minimized always selecting vector that is closest to previous state. Implementation SRF ensures a simple structure based on two three-level comparators table fits well...

The Virtual Synchronous Machine (VSM) concept is emerging as a flexible approach for controlling power electronic converters in grid-connected well stand-alone or microgrid applications. Several VSM implementations have been proposed, with the emulation of inertia and damping traditional (SM) their common feature. This paper investigates implementation based on Voltage Source Converter (VSC), where virtual swing equation provides phase reference cascaded voltage current control synchronous...

This paper proposes a combined design and control method for inductive power transfer systems that eliminates the need overrating converters in applications where coupling conditions vary significantly during operation. The is developed series-series compensated with only one active electronic converter diode rectifier connected directly to constant voltage dc bus or battery. worst-case voltampere requirements are minimized by shaping frequency characteristics of system. Rated flow...

This paper demonstrates that the sum and difference of upper lower arm voltages are suitable variables for deriving a generalized state-space model modular multilevel converter (MMC) which settles at constant equilibrium in steady-state operation. The presented modeling approach separates multiple frequency components appearing within MMC as first step derivation, to avoid containing steady state. On this basis, it is shown Park transformations three different frequencies ( <inline-formula...

This paper presents a comparison of the small-signal stability properties for virtual synchronous machines (VSMs) with dynamic and quasi-stationary representation internal machine (SM) model. It is shown that electrical equations may introduce poorly damped oscillations when realistic stator impedance values high-power SMs are used. The implementation less sensitive to model, but depends on filtering measured d - q -axes components ac-side voltage avoid instability or oscillations....