Grid Impedance Estimation Through Grid-Forming Power Converters

Fang, Jingyang; Deng, Han; Goetz, Stefan M.

doi:10.1109/tpel.2020.3010874

Cited by 81 publications

(24 citation statements)

References 24 publications

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“…Among them, the role of the synchronization control is to generate a reference angle θ in the control system, and the other part is to design a suitable control loop. Generally there are two major divisions for synchronization, namely the grid-following control and the grid-forming control [15], [28]. The grid-following control is to follow the terminal voltage phase angle through the phase-locking loop, as we have seen in Fig.…”

Section: Seclect One In Fsetmentioning

confidence: 99%

“…The second is the IM/AM based on measurement. There the IM/AM can be obtained through experiments by frequency sweeping measurement via either series voltage or shunt current injection, under black/gray-box conditions [12]- [15], where usually we cannot get all the structure and parameters of devices for the sake of commercial secrecy. Based on these IM/AM results from either theoretical modeling or measurement, the small-signal stability analysis can be further studied based on the generalized Nyquist stability criterion [16]- [19].…”

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confidence: 99%

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Black-Box Impedance Prediction of Grid-Tied VSCs Under Variable Operating Conditions

Qiu

Huang

et al. 2022

IEEE Access

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Impedance/admittance models (IM/AMs) have been widely used to analyze the small-signal stability of grid-tied power electronic devices, such as the voltage source converter (VSC). They can be either derived from theoretical analysis under white-box conditions, where all parameters and control structures are fully known, or measured based on experiments under black-box conditions, where the topology and parameters of the controllers are completely unknown. As the IM/AMs depend on specific operating conditions, it is highly desirable to develop fast algorithms for IM/AM prediction (or estimation) under the black-box and variable-operating-point conditions. This article extends the nearly-decoupled AM method for sequence AMs proposed recently by Liu et al to fit any unknown control structure, including not only grid-following VSC, but also grid-forming VSC. It is, therefore, referred to as the fully-decoupled IM (FDIM) method. Furthermore, a curve fitting method for the transfer function is proposed to expedite the algorithm, based on the information of a few disturbance frequencies only. Finally, the algorithm is verified by wide simulations and experiments under different situations, including the direct-drive wind turbine generator. The whole approach is expected to be broadly applicable to the stability analysis of power-electronic-based power systems under variable operating conditions.

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Section: Seclect One In Fsetmentioning

confidence: 99%

mentioning

confidence: 99%

Black-Box Impedance Prediction of Grid-Tied VSCs Under Variable Operating Conditions

Qiu

Huang

et al. 2022

IEEE Access

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“…Consequently, this unit does not require to have any dedicated synchronization along with power-sharing aptitudes. For the real-time implementation, this unit can be realized through an inner current loop along with an outer voltage loop [34]. This functionality is utilized as an elementary philosophy in standalone applications as the microgrid [35].…”

Section: The Role Of Voltage Source Convertersmentioning

confidence: 99%

CPS Attacks Mitigation Approaches on Power Electronic Systems With Security Challenges for Smart Grid Applications: A Review

et al. 2021

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This paper presents an inclusive review of the cyber-physical (CP) attacks, vulnerabilities, mitigation approaches on the power electronics and the security challenges for the smart grid applications. With the rapid evolution of the physical systems in the power electronics applications for interfacing renewable energy sources that incorporate with cyber frameworks, the cyber threats have a critical impact on the smart grid performance. Due to the existence of electronic devices in the smart grid applications, which are interconnected through communication networks, these networks may be subjected to severe cyber-attacks by hackers. If this occurs, the digital controllers can be physically isolated from the control loop. Therefore, the cyber-physical systems (CPSs) in the power electronic systems employed in the smart grid need special treatment and security. In this paper, an overview of the power electronics systems security on the networked smart grid from the CP perception, as well as then emphases on prominent CP attack patterns with substantial influence on the power electronics components operation along with analogous defense solutions. Furthermore, appraisal of the CPS threats attacks mitigation approaches, and encounters along the smart grid applications are discussed. Finally, the paper concludes with upcoming trends and challenges in CP security in the smart grid applications.

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“…Microgrid technology has elicited considerable attention with the growing maturity of new energy generation technology. Microgrids contain distributed generators (DGs), energy storage units, converters, loads, and protection and control devices [1]. They can be connected to the main grid for grid-connected operation or isolated from it [2].…”

Section: Introductionmentioning

confidence: 99%

Precise Reactive Power-Voltage Droop Control of Parallel Virtual Synchronous Generators That Considers Line Impedance

et al. 2021

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Problems such as high power coupling, low distribution accuracy, and insufficient reactive power-voltage droop accuracy occur when distributed generators are operated in parallel due to the influence of line impedance. The precise control of output reactive power and voltage is difficult to achieve using traditional virtual synchronous generator (VSG) control. Taking this into consideration, this study proposes a virtual synchronous generator reactive power-voltage integrated control strategy that considers line parameters to solve this problem. First, the impedance voltage drop of the line is compensated for in accordance with local information control to ensure the consistency of the control voltage in parallel operation of distributed generators and to realize the precise droop control of reactive power and the voltage of the point of common coupling (UPCC). Second, virtual negative impedance control is added to change the equivalent output impedance characteristics of the system and achieve power decoupling. On this basis, the active frequency and reactive voltage decoupling control effect of the improved control strategy is quantified and analyzed using the relative gain matrix. The accuracy of reactive power distribution and droop control is theoretically derived and analyzed by establishing a small-signal model of a two-machine parallel system. Finally, the accuracy and effectiveness of the proposed integrated control strategy are verified via a simulation model and an experimental platform for parallel operation. Results show that the proposed integrated control strategy can effectively solve the problems of power decoupling and accurate distribution, reduce system loop current, and realize accurate reactive power-voltage droop. Compared with the traditional VSG control strategy, the dynamic deviation of UPCC is reduced by at least 40% when a large-scale load disturbance occurs.

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Grid Impedance Estimation Through Grid-Forming Power Converters

Cited by 81 publications

References 24 publications

Black-Box Impedance Prediction of Grid-Tied VSCs Under Variable Operating Conditions

Black-Box Impedance Prediction of Grid-Tied VSCs Under Variable Operating Conditions

CPS Attacks Mitigation Approaches on Power Electronic Systems With Security Challenges for Smart Grid Applications: A Review

Precise Reactive Power-Voltage Droop Control of Parallel Virtual Synchronous Generators That Considers Line Impedance

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