Impedance-Based Stability Criterion for Grid-Connected Inverters

Sun, Jian

doi:10.1109/tpel.2011.2136439

Cited by 1,965 publications

(1,015 citation statements)

References 11 publications

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“…As discussed in Section 4, the renewable energy systems have to be able to operate both in grid-feeding and grid-forming modes [23,24,99]. In grid-feeding mode [23], the system is stable at all the operating points of the PV generator, if the associated converters are properly designed as shown in Figure 18.…”

Section: Stability Issuesmentioning

confidence: 99%

Review of PV Generator as an Input Source for Power Electronic Converters

et al. 2017

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Voltage-type sources have dominated as an input source for power electronics converters for a long type. The existence of duality implies that there are also current-type sources. The growing application of renewable energy sources such as wind and solar energy has evidently shown that the current-type input sources exist in reality such as photovoltaic (PV) generator or the feedback technique used in controlling the power electronics converters in the renewable energy systems changes the power electronic converters to behaving as such. The recent research on renewable energy systems has indicated that the current-type input sources are very challenging input sources affecting the dynamics of the interfacing converters profoundly. This paper provides a comprehensive survey of the effects of the PV generator on the dynamic behavior of the corresponding interfacing power electronic converters.

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Section: Stability Issuesmentioning

confidence: 99%

Review of PV Generator as an Input Source for Power Electronic Converters

et al. 2017

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“…To guarantee robustness to grid impedance variation, the grid-connected converter should satisfy the following criteria [4,27,28]: (1) The current control is stable when Z ' g(s) = 0; and (2) The impedance ratio Z ' g(s)/Zcon(s) satisfies the Nyquist criterion. That is, if the gains of Zcon(s) and Z ' g(s) intersect at the frequency fcross, the phase margin at fcross (PMcross) must be positive, i.e., PMcross > 0°, and as large as possible.…”

Section: Impedance-based Stability Analysis Under Weak Grid Conditionsmentioning

confidence: 99%

Improved Capacitor Voltage Feedforward for Three-Phase LCL-Type Grid-Connected Converter to Suppress Start-Up Inrush Current

et al. 2017

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Three-phase active damping LCL-type grid-connected converters are usually used in distributed power generation systems. However, serious inrush current will be aroused when the grid-connected converter starts, especially in rectifier mode, if no effective control method is taken. The point of common coupling (PCC) voltage feedforward is usually used to suppress start-up inrush current. Unfortunately, it will introduce a positive feedback loop related to the grid current and grid impedance under weak grid conditions, and therefore, the grid current will be distorted and the system stability margin will be significantly reduced. To solve the above problems, this paper proposes a simple method based on a d-axis fundamental positive-sequence component of filter capacitor voltage feedforward, without extra sensors and software resources. With the proposed method, it is possible to suppress the start-up inrush current and maintain the grid current quality and system stability under weak grid conditions. The mechanism of start-up inrush current and the effectiveness of the method for inrush current suppression are analyzed in detail. Then, the influences of different feedforward methods on system stability are analyzed under weak grid conditions by the impedance model of grid-connected converter. Finally, experimental results verify the validity of the proposed method.

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“…The impedance method has been widely used in grid-connected systems. The impedance of a grid-connected voltage-source converter is critical to any analysis of the stability and resonance between the converter and the grid, including that with the filter of the converter [34]. Particularly, a grid-connected voltage-source converter can be modeled as a current source in parallel with an impedance [35], and the stability of the system is determined by the magnitude of the impedance that can be improved by increasing the output impedance at the harmonic frequencies [36].…”

Section: Controlled Source Electrical Equipmentmentioning

confidence: 99%

Improving the Stability and Accuracy of Power Hardware-in-the-Loop Simulation Using Virtual Impedance Method

et al. 2016

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Abstract:Power hardware-in-the-loop (PHIL) systems are advanced, real-time platforms for combined software and hardware testing. Two paramount issues in PHIL simulations are the closed-loop stability and simulation accuracy. This paper presents a virtual impedance (VI) method for PHIL simulations that improves the simulation's stability and accuracy. Through the establishment of an impedance model for a PHIL simulation circuit, which is composed of a voltage-source converter and a simple network, the stability and accuracy of the PHIL system are analyzed. Then, the proposed VI method is implemented in a digital real-time simulator and used to correct the combined impedance in the impedance model, achieving higher stability and accuracy of the results. The validity of the VI method is verified through the PHIL simulation of two typical PHIL examples.

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Impedance-Based Stability Criterion for Grid-Connected Inverters

Cited by 1,965 publications

References 11 publications

Review of PV Generator as an Input Source for Power Electronic Converters

Review of PV Generator as an Input Source for Power Electronic Converters

Improved Capacitor Voltage Feedforward for Three-Phase LCL-Type Grid-Connected Converter to Suppress Start-Up Inrush Current

Improving the Stability and Accuracy of Power Hardware-in-the-Loop Simulation Using Virtual Impedance Method

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