Xilinx System Generator-based Rapid Prototyping of Different Control Strategies for Solid State Transformer

This paper proposes an overall practical stability assessment for a multi-port single-phase solid-state transformer (MS3T) in the electromagnetic timescale. When multiple stable subsystems are combined into one MS3T, the newly formed MS3T has a certain possibility to be unstable. Thus, this paper discusses the stability assessment of the MS3T in detail. First and foremost, the structure of the MS3T and its three stage control strategies are proposed. Furthermore, the stability analysis of each of the MS3T’s subsystems is achieved through the closed loop transfer function of each subsystem, respectively, including an AC-DC front-end side converter, dual active bridge (DAB) with a high-frequency (HF) or medium-frequency (MF) transformer, and back-end side incorporating DC-AC and dc-dc converters. Furthermore, the practical impedance stability criterion in the electromagnetic timescale, which only requires two current sensors and one external high-bandwidth small-signal sinusoidal perturbation current source, is proposed by the Gershgorin theorem and Kirchhoff laws. Finally, the overall stability assessment, based on a modified impedance criterion for the MS3T is investigated. The overall practical stability assessment of the MS3T can be validated through extensive simulation and hardware results.

Download Full-text

Rapid prototyping of power electronics converters for photovoltaic system application using Xilinx System Generator

IET Power Electronics ◽

10.1049/iet-pel.2013.0736 ◽

2014 ◽

Vol 7 (9) ◽

pp. 2269-2278 ◽

Cited By ~ 39

Author(s):

Rajasekar Selvamuthukumaran ◽

Rajesh Gupta

Keyword(s):

Rapid Prototyping ◽

Power Electronics ◽

System Application ◽

Photovoltaic System ◽

System Generator ◽

Power Electronics Converters ◽

Xilinx System Generator

Download Full-text

A Hierarchical Coordinative Control Strategy for Solid State Transformer Based DC Microgrids

Applied Sciences ◽

10.3390/app10196853 ◽

2020 ◽

Vol 10 (19) ◽

pp. 6853 ◽

Cited By ~ 1

Author(s):

Zheng Li ◽

Tao Zheng ◽

Yani Wang ◽

Chang Yang

Keyword(s):

Solid State ◽

Control Strategy ◽

Control Strategies ◽

Access Point ◽

Voltage Response ◽

Solid State Transformer ◽

Independent Control ◽

Dc Microgrid ◽

Energy Internet ◽

Dynamic Voltage

A solid state transformer (SST), as a kind of energy router in the Energy Internet, provides a unified access point for AC or DC distributed power subjects. However, the DC-link capacitors inside the SST will suffer huge voltage fluctuations when the output power of the microgrid changes dramatically. With respect to this problem, caused by the random and intermittent characteristics of distributed generation (DG), a hierarchical coordinative control strategy is proposed. Compared with the common independent control, the proposed method not only makes full use of the regulation capacity of super capacitors, but also enhances the dynamic power tracking speed and reduces the speed difference between different stages of an SST. The dynamic voltage response under the proposed method is analyzed in frequency domain and compared with the independent control. To validate the effectiveness of the coordinative control strategy, a simulation model of an SST-based grid-connected DC microgrid system is established, and the topology of the SST is improved. The voltage stability of the DC bus is compared under different control strategies, and the coordinative control strategy is also verified, effectively under transition conditions.

Download Full-text

Current Control Strategies for a Star Connected Cascaded H-Bridge Converter Operating as MV-AC to MV-DC Stage of a Solid State Transformer

Energies ◽

10.3390/en14154607 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4607

Author(s):

Sebastian Stynski ◽

Marta Grzegorczyk ◽

Cezary Sobol ◽

Radek Kot

Keyword(s):

Solid State ◽

Control Algorithm ◽

Power Flow ◽

Low Voltage ◽

Control Strategies ◽

Current Control ◽

Renewable Energy Resources ◽

Solid State Transformer ◽

Voltage Transformer ◽

Current Harmonics

Nowadays, the increasing number of nonlinear loads and renewable energy resources pose new challenges for the standard electrical grid. Conventional solutions cannot handle most of them. The weakest component in the whole system is a conventional distribution (converting medium to low AC voltage) transformer. It should not operate with unbalanced, heavily distorted voltage and cannot control power flow or compensate current harmonics. One of the promising solutions to replace the conventional transformer and thus minimize power flow and grid distortions is a power electronics device called a solid state transformer (SST). Depending on the SST topology, it can have different functionalities, and, with the proper control algorithm, it is able to compensate any power imbalances in both low voltage (LV) and medium voltage (MV) grid sides. In the case of a three energy conversion stage SST, the LV and the MV stages can be treated separately. This paper focuses on the MV-AC to the MV-DC stage only based on a star-connected cascaded H-bridge converter. In this paper, a simple control solution for such a converter enabling different current control strategies to distribute power among the phases in an MV grid in the case of voltage imbalances is proposed. Simulation and experimental results proved good performance and verified the validity of the proposed control algorithm.

Download Full-text