Predictive Voltage Control for Grid-Forming Power Converters with Virtual Output Impedance

Author(s):  
Johnny Chhor ◽  
Benedikt Lammersmann
2019 ◽  
Vol 9 (5) ◽  
pp. 952 ◽  
Author(s):  
S. Mohamed ◽  
P. Jeyanthy ◽  
D. Devaraj ◽  
M. Shwehdi ◽  
Adel Aldalbahi

The high penetration level of solar photovoltaic (SPV) generation systems imposes a major challenge to the secure operation of power systems. SPV generation systems are connected to the power grid via power converters. During a fault on the grid side; overvoltage can occur at the direct current link (DCL) due to the power imbalance between the SPV and the grid sides. Subsequently; the SPV inverter is disconnected; which reduces the grid reliability. DC-link voltage control is an important task during low voltage ride-through (LVRT) for SPV generation systems. By properly controlling the power converters; we can enhance the LVRT capability of a grid-connected SPV system according to the grid code (GC) requirements. This study proposes a novel DCL voltage control scheme for a DC–DC converter to enhance the LVRT capability of the two-stage grid-connected SPV system. The control scheme includes a “control without maximum power point tracking (MPPT)” controller; which is activated when the DCL voltage exceeds its nominal value; otherwise, the MPPT control is activated. Compared to the existing LVRT schemes the proposed method is economical as it is achieved by connecting the proposed controller to the existing MPPT controller without additional hardware or changes in the software. In this approach, although the SPV system will not operate at the maximum power point and the inverter will not face any over current challenge it can still provide reactive power support in response to a grid fault. A comprehensive simulation was carried out to verify the effectiveness of the proposed control scheme for enhancing the LVRT capability and stability margin of an interconnected SPV generation system under symmetrical and asymmetrical grid faults.


Author(s):  
Il-Yop Chung Il-Yop Chung ◽  
Phi Hai Trinh Phi Hai Trinh ◽  
H. Cho ◽  
Ju-Yong Kim Ju-Yong Kim ◽  
Jin-Tae Cho Jin-Tae Cho ◽  
...  

Author(s):  
Jian Rong Huang ◽  
Sophia Chien-Hui Wang ◽  
Chia Jung Lee ◽  
Eddie Kuo-Lung Tseng ◽  
Dan Chen

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 493 ◽  
Author(s):  
Kumars Rouzbehi ◽  
Arash Miranian ◽  
Juan Manuel Escaño ◽  
Elyas Rakhshani ◽  
Negin Shariati ◽  
...  

This paper develops a data-driven strategy for identification and voltage control for DC-DC power converters. The proposed strategy does not require a pre-defined standard model of the power converters and only relies on power converter measurement data, including sampled output voltage and the duty ratio to identify a valid dynamic model for them over their operating regime. To derive the power converter model from the measurements, a local model network (LMN) is used, which is able to describe converter dynamics through some locally active linear sub-models, individually responsible for representing a particular operating regime of the power converters. Later, a local linear controller is established considering the identified LMN to generate the control signal (i.e., duty ratio) for the power converters. Simulation results for a stand-alone boost converter as well as a bidirectional converter in a test DC microgrid demonstrate merit and satisfactory performance of the proposed data-driven identification and control strategy. Moreover, comparisons to a conventional proportional-integral (PI) controllers demonstrate the merits of the proposed approach.


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