Self-Synchronizing VSM With Seamless Operation During Unintentional Islanding Events

Wang

IEEE Open J. Power Electron.

et al. 2022

This paper addresses the transient stability of gridforming (GFM) inverters when transitioning from the islanded to grid-connected mode. It is revealed that the reconnection of the GFM inverters to the main grid can be equivalent to a step change of the active power reference, whose impact is closely related with the local load, active power reference of GFM inverter, and shortcircuit ratio (SCR) of the grid. Such equivalent disturbance may cause GFM inverters lose the synchronism with the grid. To avoid loss of synchronization, the existence of equilibria of GFM inverter after reconnecting it with the grid is examined, considering the varying SCR. Then, the parametric effects of power controllers on the transient stability are characterized by using phase portraits, which shed clear insights into the controller design for reliably reconnecting GFM inverters with grid. Lastly, all the theoretical findings are confirmed by experimental tests.

Section: Impact Of Q-v Droop Control On the Transient Stabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transient Stability Analysis for Grid-Forming Inverters Transitioning from Islanded to Grid-Connected Mode

Wang

IEEE Open J. Power Electron.

et al. 2022

“…VSMs have been proven as an effective method for both grid supporting and grid forming operations, facing many stability issues and providing virtual inertia to the power system [10]- [12]. Nowadays, this transition between grid forming and grid supporting control strategies is being addressed very often in the literature [13]- [15].…”

Section: Introductionmentioning

confidence: 99%

VSC Control Strategy for Systems with high penetration of Power Electronic Converters

Armas¹,

Rodriguez-Amenedo²,

Arnaltes³

et al. 2024

RE&PQJ

This paper presents a Voltage Source Converter (VSC) with an implemented Virtual Synchronous Machine (VSM) control strategy, which is able to work in both grid-tied and islanded mode, providing inertia to the grid and regulating the frequency and the voltage of the system. Those capabilities are necessary to make possible a high penetration of power electronic converters in the power grid. Converters work in parallel with the conventional generators while being able to deal with islanding or some other critical grid events. The proposed control strategy has been tested in a test bench with a synchronous generator (SG). When islanding the VSC, the converter demonstrates its grid forming capabilities controlling the frequency and voltage of the microgrid. The VSM control has proved its grid forming and grid supporting capabilities, without switching between control modes, making it ideal to react to different grid events and showing a soft transition between grid-tied and islanded operation modes.

“…Different minimization criteria for OSV controller are described in [19] and this paper uses quadratic cost function minimization to compute the future control samples. The OSV controller for voltagecontrolled inverters, has been used in the past research work [20][21][22], where the output voltages of an inverter, are strictly governed by the minimization criterion, however, this property is not fully explored for reference harmonic voltage injection. This work explores this property to formulate a generalized algorithm, which voluntarily injects harmonic grid voltages, to improve power quality in the grid connected and off-grid distributed generation systems.…”

Section: Introductionmentioning

confidence: 99%

Harmonic Voltage Control in Distributed Generation Systems Using Optimal Switching Vector Strategy

Srinivas

Singh

Mishra

et al. 2022

IEEE Systems Journal

Self Cite

With increased penetration of renewable power and the nonlinear loads in the distributed generation (DG) systems, increased power quality concerns are exhibited, especially the challenges associated with the current and voltage harmonics in the system. Various conventional harmonic compensation techniques are developed for voltage-controlled DG inverters in past, majority involve either multiple proportional-integral (PI) or proportional-resonant (PR) controllers in eliminating grid current harmonics. The current-controlled inverters, on the other hand, are not preferred in industrial applications, accounting to their wide variations in the switching frequency. A novel and adaptive harmonic-voltage control is developed here, for voltagecontrolled DG inverters, which neither uses any PI regulators, nor imposes stability issues associated with non-ideal implementation of infinite gains of PR controllers. Interestingly, the developed control logic can be used for DG inverters, both in grid connected and off-grid operational modes. Furthermore, this strategy allows network operator to be used as an additional supplement that can be enabled/disabled as per the network requirement. The control logic exploits the property of optimal-switching-vector (OSV) controller i.e. accurate output voltage tracking. Simulations results demonstrate the effectiveness of the controller, to suppress grid current harmonics and load voltage harmonics in gridinterfaced and off-grid modes respectively, ultimately satisfying the mandatory IEEE standard-1547. Experimental results verify the viability of the controller for practical applications.