Charge-Based Droop Control Addressing Control Saturation for Low-Inertia Converters

Conference · Sun Oct 09 04:00:00 EDT 2022 · IEEE Energy Conversion Congress and Exposition (ECCE)

DOI:https://doi.org/10.1109/ecce50734.2022.9947700· OSTI ID:1923362

An, Zheng ^[1]; Kandula, Rajendra Parasad ^[2]; Benzaquen, Joseph ^[3]; Divan, Deepak ^[3]

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1. Georgia Inst. of Technology, Atlanta, GA (United States); Georgia Institute of Technology
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Georgia Inst. of Technology, Atlanta, GA (United States)

With bulky dc-link capacitors/inductors, traditional voltage-source converters (VSCs) and current-source converters (CSCs) feature a large inertia to facilitate the converter control under large transients. To achieve high power density with reduced cost, low-inertia converters (LICs) featuring significantly reduced dc-link capacitors/inductors have attracted growing attention. However, without bulky dc-link energy buffer, LICs are prone to control saturation under large transients, resulting in undesired oscillation and instability. This issue cannot be managed by traditional proportional-integral based control due to the low inertia. And it will deteriorate when several LICs are connected in series. To address this challenge in LICs, a model-predictive control (MPC) with a computation-inexpensive feed-forward compensation method has been proposed to provide fast dynamic responses. But it would suffer control saturation under larger transients that degrades the control performance. In this article, a charge-based droop control (CDC) is proposed to address this remaining challenge. This paper firstly analyzes the control saturation challenge in LICs by using a tri-port soft-switching solid-state transformer as an example. Next, the operating principle of the proposed CDC are introduced. Two different implementation approaches are discussed in detail. Lastly, the proposed scheme is validated in simulation with a high-fidelity model of hardware prototype. As a result, the proposed CDC eliminated the 2 kHz oscillation and reduced the dc-link ripple and overshoot due to control saturation by 75% and 50%, respectively.

• Research Organization: Georgia Inst. of Technology, Atlanta, GA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
• DOE Contract Number: EE0008351
• OSTI ID: 1923362
• Conference Information: Journal Name: IEEE Energy Conversion Congress and Exposition (ECCE)
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
Droop control
control saturation
current-source converters
low inertia
soft-switching solid-state transformer