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

Ning Gao; Shun Sang; Rui Li; Xu Cai

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

Vol. 17, No. 3, pp. 756-765, May 2017

10.6113/JPE.2019.17.3.756

Battery energy storage system

Impedance model

Power conversion system

Virtual resistors

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Abstract

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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Cite this article

[IEEE Style]

N. Gao, S. Sang, R. Li, X. Cai, "An Improved Control Method for Power Conversion System under a Weak Grid by the Adoption of Virtual Resistors," Journal of Power Electronics, vol. 17, no. 3, pp. 756-765, 2017. DOI: 10.6113/JPE.2019.17.3.756.

[ACM Style]

Ning Gao, Shun Sang, Rui Li, and Xu Cai. 2017. An Improved Control Method for Power Conversion System under a Weak Grid by the Adoption of Virtual Resistors. Journal of Power Electronics, 17, 3, (2017), 756-765. DOI: 10.6113/JPE.2019.17.3.756.