Influence analysis of the effects of an inductive-resistive weak grid over L and LCL filter current hysteresis controllers

Cobreces, Santiago; Bueno, Emilio; Rodríguez, Francisco; Huerta, F.; Rodríguez, Pedro

doi:10.1109/epe.2007.4417594

Cited by 50 publications

(33 citation statements)

References 18 publications

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“…The grid-connected/islanded modes of GCIs will also frequently change the equivalent grid impedance in DPGSs [3]. With the increase of the penetration rate of GCIs, large-range perturbation of the equivalent grid impedance on the PCC may occur more and more frequently, and weaken the control performance of GCIs in DPGSs.…”

Section: Introductionmentioning

confidence: 99%

H∞ Robust Control of an LCL-Type Grid-Connected Inverter with Large-Scale Grid Impedance Perturbation

Wang

Zeng

et al. 2018

Energies

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Abstract:In the distributed power generation system (DPGS), there may be a large range perturbation values of equivalent grid impedance at the point of common coupling (PCC). Perturbation of the impedance will cause resonant frequency variation of the Inductance Capacitance Inductance (LCL) filter on a large scale, affecting the quality of the grid current of the grid-connected inverter (GCI) and even causing resonance. To deal with this problem, a novel H ∞ robust control strategy based on mixed-sensitivity optimization is proposed in this paper. Its generalized controlled object is augmented by properly selecting weighting functions in order to consider both tracking performance around power frequency and the stability margin in a high frequency of the GCI. For convenient implementation, the H ∞ robust controller is simplified by model reduction from the seventh order to the third order. By comparison with a traditional control strategy with a quasi-proportional resonance controller, the proposed H ∞ robust control strategy avoids crossing 180 degrees at the resonant frequency point in the phase frequency characteristic of current loop, and moves the phase frequency characteristic left. It guarantees a sufficient margin of stability throughout the designed range of grid impedance perturbation values and avoids the difficulty of parameter setting. Finally, the experimental results support the theoretical analyses and demonstrate the feasibility of the proposed strategy.

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Section: Introductionmentioning

confidence: 99%

H∞ Robust Control of an LCL-Type Grid-Connected Inverter with Large-Scale Grid Impedance Perturbation

Wang

Zeng

et al. 2018

Energies

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“…An LCL filter has some advantages over a common L filter [4], due to the fact that an LCL filter presents increased attenuation of high order harmonics while allowing the use of lower size inductances. However, when using an LCL filter, resonances may arise which must be dealt with [5]. The resonance problem is dealt with in the lab converter prototype, switched at 4950 Hz, by using a notch filter designed to match the resonance frequency.…”

Section: B Three-phase Convertermentioning

confidence: 99%

Distributed Generation with Voltage Control Capability in the Low Voltage Network

Sulla¹,

Björnstedt²,

Samuelsson³

2010

REPQJ

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Abstract. Small-scale distributed generators connected to the low voltage network are generally operated with unity power factor. However, controlling their reactive power injection would have an impact on the voltage at their connection point, if the network is sufficiently weak and inductive. The purpose of this paper is to investigate how a small-scale distributed generator connected to a low voltage network through a power electronic converter can be controlled to improve the voltage quality at its connection point.The possibility to control the voltage at a point in the low voltage network by reactive power injection is limited by two factors, the small rating of the distributed generator compared to the short-circuit power at its connection point and the resistive nature of the low voltage cables. Here, a scheme for inductively decoupling the distributed generator connection point from the network is proposed and evaluated. For this purpose, an inductance is placed between the network and the generator, allowing voltage regulation by reactive power injection.Simulation results and lab measurements show that the proposed scheme improves the voltage quality at the microturbine connection point.

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“…In the experimental environment, the grid inductance L g is set to be much larger than its resistance. Therefore, R g has little effect on the loci and is omitted in the analysis [28] . As shown in Fig.…”

Section: Filter Capacitor 56μfmentioning

confidence: 99%

An Improved Control Method for Power Conversion System under a Weak Grid by the Adoption of Virtual Resistors

Gao¹,

Sang²,

Li³

et al. 2017

Journal of Power Electronics

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The control of the power conversion system (PCS) in a battery energy storage system has a challenge due to the existence of grid impedance. This paper studies an impedance model of an LCL-based PCS in the d-q domain. The feature of a PCS connected to a weak grid is unveiled by use of an impedance model and a generalized Nyquist criterion. It is shown that the interaction between grid impedance and the PCS destabilizes the cascaded system in certain cases. Therefore, this paper proposes a novel control method that adopts virtual resistors to overcome this issue. The improvement in the control loop leads the PCS to a more stable condition than the conventional method. Impedance measurement is implemented to verify the correctness of the theoretical analysis. Experimental results obtained from a down-scaled prototype indicate that the proposed control method can improve the performance of the PCS under a weak grid.

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Influence analysis of the effects of an inductive-resistive weak grid over L and LCL filter current hysteresis controllers

Cited by 50 publications

References 18 publications

H∞ Robust Control of an LCL-Type Grid-Connected Inverter with Large-Scale Grid Impedance Perturbation

H∞ Robust Control of an LCL-Type Grid-Connected Inverter with Large-Scale Grid Impedance Perturbation

Distributed Generation with Voltage Control Capability in the Low Voltage Network

An Improved Control Method for Power Conversion System under a Weak Grid by the Adoption of Virtual Resistors

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