Transient Damping Method for Improving the Synchronization Stability of Virtual Synchronous Generators

Xiong, Xinhong; Wu, Chao; Hu, Bin; Pan, Donghua; Blaabjerg, Frede

doi:10.1109/tpel.2020.3046462

Cited by 83 publications

(44 citation statements)

References 35 publications

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“…Instead, a virtual damping control and a virtual reactance model are introduced in [97] to suppress the power oscillations of paralleled synchronverters during load disturbances. In [98], a similar virtual damping control is integrated into the active power control loop of VSGs to dampen post-fault oscillations. Unlike the proposal in [97], which employs a high-pass filter to detect frequency transients, this damping control utilizes a PLL for the same purpose.…”

Section: ) Transient Stabilitymentioning

confidence: 99%

Grid Forming Inverter Modeling, Control, and Applications

et al. 2021

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This paper surveys current literature on modeling methods, control techniques, protection schemes, applications, and real-world implementations pertaining to grid forming inverters (GFMIs). Electric power systems are increasingly being augmented with inverter-based resources (IBRs). While having a growing share of IBRs, conventional synchronous generator-based voltage and frequency control mechanisms are still prevalent in the power industry. Therefore, IBRs are experiencing a growing demand for mimicking the behavior of synchronous generators, which is not possible with conventional grid following inverters (GFLIs). As a solution, the concept of GFMIs is currently emerging, which is drawing increased attention from academia and the industry. This paper presents a comprehensive review of GFMIs covering recent advancements in control technologies, fault ride-through capabilities, stability enhancement measures, and practical implementations. Moreover, the challenges in adding GFMIs into existing power systems, including a seamless transition from grid-connected mode to the standalone mode and vice versa, are also discussed in detail. Recently commissioned projects in Australia, the UK, and the US are taken as examples to highlight the trend in the power industry in adding GFMIs to address issues related to weak grid scenarios. Research directions in terms of voltage control, frequency control, system strength improvement, and regulatory framework are also discussed. This paper serves as a resource for researchers and power system engineers exploring solutions to the emerging problems with high penetration of IBRs, focusing on GFMIs.INDEX TERMS Current control, fault ride-through, grid forming inverters, power synchronization control, small-signal and transient stability, virtual inertia.

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Section: ) Transient Stabilitymentioning

confidence: 99%

Grid Forming Inverter Modeling, Control, and Applications

et al. 2021

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“…In this study, the grid is represented by a Thevenin equivalent as standard model used to assess the performance of VSC-FRT [15,16,23,34,42]…”

Section: Dual Vsm Structure Configurationmentioning

confidence: 99%

“…The second approach, which is adopted in this article, is to enhance the control structure, which can enable the FRT capability with lower cost as the same hardware is used. For the FRT capability enhancement of a VSC controlled as a VSM, the researchers tend to build a VSM structure with an inner positive sequence Current Control (CC) loop [13][14][15][16][17][18][19][20][21][22][23], or positive and negative (pn) sequence controllers [18,24]. In addition to the use of the current loop, some ancillary controllers have been used to enhance the FRT performance such as virtual impedance [13,15,17,19,20,[25][26][27], current reference saturation [18,[28][29][30][31], and some structures merging both techniques [14,16].…”

Section: Introductionmentioning

confidence: 99%

New Fault Detection Algorithm for an Improved Dual VSM Control Structure With FRT Capability

Abdel-Rahim¹,

Smailes

Ahmed

et al. 2021

IEEE Access

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Grid forming converters are a promising solution to enhance the stability of electrical networks with a high penetration of renewable generation. Virtual Synchronous Machines (VSM) are a particular type of grid forming converter, which can be implemented without an inner Current Control (CC) loop. This VSM implementation can provide a better inertial response than other grid forming structures with an inner CC. However, it cannot limit the current through the converter during a fault. A standard solution uses a VSM as the primary controller with a conventional inner CC acting as a backup controller during fault conditions, referred to here as a Dual VSM control structure. The switching action between the primary and the backup controllers is dependent on an accurate Fault Detection Algorithm (FDA). The conventional FDA mentioned in the literature has limitations in particular but not uncommon scenarios. The article shows the limitations of the conventional FDA in weak grids and unbalanced conditions and introduces a new FDA with improved performance. Two types of sensitivity analysis are used to study the dynamics of the proposed control approach. The First is the sensitivity of the proposed control structure to different fault locations in strong and weak grids. The Second is the sensitivity of the controller response to changing controller parameters. The second analysis is introduced as a reference for tuning and improvement of the control structure introduced.

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“…In conventional damping techniques, the synchronization angle (power angle), , is estimated using one signal, namely, the control of active power as in VSC or the control of DClink voltage as in matching control. However, in the proposed damping method, the synchronization angle is calculated using a linear combination between 4 signals, namely, ( ) that depends on the DC-link voltage regulation (as in matching control), ( ) that depends on the regulation of the active power (as in a special type of VSM swing equation) and ( ) / ( ) , that depends on the / regulation (as in PLL synchronization techniques) as shown in (16). This combined method is more accurate and rapid in estimating the synchronization angle since it depends on the contribution of 4 signals instead of a single signal as in conventional techniques.…”

Section: B Mapping Matrix and Pi Controller Designmentioning

confidence: 99%

“…Therefore, recent research activities have attempted to control the grid-tied converters in a manner that emulates the behavior of SMs by adapting them to serve as grid-forming converters (GFC) instead of grid-following converters. To this end, different promising techniques have been proposed, such as droop-based grid-forming control methods [4,5], virtual synchronous machine (VSM) [6][7][8], synchronverter [9], virtual oscillator control [10], voltage-controlled inverter [11], matching control [12][13][14][15], power synchronization control [16], and direct power control [17].…”

Section: Introductionmentioning

confidence: 99%

Improved Damping Control Method for Grid-Forming Converters Using LQR and Optimally Weighted Feedback Control Loops

et al. 2021

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Power grid pattern is expected to evolve from generator-based power systems towards converter-based systems in the forthcoming decades. Therefore, grid-forming converters will be pertinent to interconnected power grids in pursuance of enhancement their resilience against disturbances. This paper introduces a new efficient damping control method for gridforming converters that provides a smooth power modulation and an efficient damping response against frequency and voltage deviations. First, an averaged state-space representation for a grid forming application in dq synchronization frame is derived. Based on this model, a new hybrid damping controller, including the concept of state feedback control and PI control, is proposed to address the main issues in existing controllers. The state feedback controller is optimally designed using a linearquadratic regulator (LQR) approach to optimize the system performance. Moreover, the PI controller is optimally designed using the pattern search algorithm. The proposed damping control method integrates optimally between the control loops through a mapping matrix to rapidly synchronize with the grid and efficiently damp the oscillations. Simulations are carried out to prove the proposed method robustness. Finally, a comparative study using controller hardware-in-the-loop (CHiL) is employed against conventional system to validate the proposed damping method.INDEX TERMS Grid-forming converters, inverter dominated grid, weak grid, virtual inertia, damping emulation, distributed generation, LQR design, pattern search.

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Transient Damping Method for Improving the Synchronization Stability of Virtual Synchronous Generators

Cited by 83 publications

References 35 publications

Grid Forming Inverter Modeling, Control, and Applications

Grid Forming Inverter Modeling, Control, and Applications

New Fault Detection Algorithm for an Improved Dual VSM Control Structure With FRT Capability

Improved Damping Control Method for Grid-Forming Converters Using LQR and Optimally Weighted Feedback Control Loops

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