scholarly journals Demonstration of Converter Control Interactions in MMC-HVDC Systems

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 175
Author(s):  
Jinlei Chen ◽  
Sheng Wang ◽  
Carlos E. Ugalde-Loo ◽  
Wenlong Ming ◽  
Oluwole D. Adeuyi ◽  
...  
Keyword(s):  
Power Control ◽  
Current Control ◽  
Operating Conditions ◽  
The Other ◽  
Constant Current ◽  
Droop Control ◽  
Dc Voltage ◽  
Control Scheme ◽  
Point To Point ◽  
Dc Current

Although the control of modular multi-level converters (MMCs) in high-voltage direct-current (HVDC) networks has become a mature subject these days, the potential for adverse interactions between different converter controls remains an under-researched challenge attracting the attention from both academia and industry. Even for point-to-point HVDC links (i.e., simple HVDC systems), converter control interactions may result in the shifting of system operating voltages, increased power losses, and unintended power imbalances at converter stations. To bridge this research gap, the risk of multiple cross-over of control characteristics of MMCs is assessed in this paper through mathematical analysis, computational simulation, and experimental validation. Specifically, the following point-to-point HVDC link configurations are examined: (1) one MMC station equipped with a current versus voltage droop control and the other station equipped with a constant power control; and (2) one MMC station equipped with a power versus voltage droop control and the other station equipped with a constant current control. Design guidelines for droop coefficients are provided to prevent adverse control interactions. A 60-kW MMC test-rig is used to experimentally verify the impact of multiple crossing of control characteristics of the DC system configurations, with results verified through software simulation in MATLAB/Simulink using an open access toolbox. Results show that in operating conditions of 650 V and 50 A (DC voltage and DC current), drifts of 7.7% in the DC voltage and of 10% in the DC current occur due to adverse control interactions under the current versus voltage droop and power control scheme. Similarly, drifts of 7.7% both in the DC voltage and power occur under the power versus voltage droop and current control scheme.

The Evolution for Voltage and Reactive Power Control in Smart Distribution Systems

2012 ◽  
Vol 13 (1) ◽  
Author(s):  
Hany E. Farag ◽  
Ehab F. El-Saadany ◽  
Ravi Seethapathy
Keyword(s):  
Smart Grid ◽  
Power Control ◽  
Distribution Systems ◽  
Reactive Power ◽  
Voltage Regulation ◽  
Current Control ◽  
Multi Agent Systems ◽  
Reactive Power Control ◽  
Control Scheme ◽  
Control Schemes

This paper has been arisen to show the necessity of the evolution for voltage and reactive power control in distribution systems from conventional to active control techniques. The paper addresses the drawbacks and conflicts that the conventional voltage and reactive power control schemes will face in future distribution systems, especially with high penetration of Distributed Generation (DG). Some of these drawbacks have been verified by carrying out various simulation studies for different IEEE unbalanced radial distribution test systems. The results show that applying the conventional utility voltage regulation control practices in smart grid configuration is intolerable. Therefore, the issue of voltage and reactive power control in smart distribution systems is significant and an evolution of the current control schemes from passive to active is necessary. Using the smart grid technologies, a distributed single layer cooperative control scheme between substation regulators, line regulators and DG units has been proposed. The proposed cooperative scheme is based on the concept of multi-agent systems. Simulation results have been carried out to show the effectiveness of the proposed control scheme.

scholarly journals An accurate reactive power control study in virtual flux droop control

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 948-953
Author(s):  
Aimeng Wang ◽  
Jia Zhang
Keyword(s):  
Power Control ◽  
Reactive Power ◽  
Control Method ◽  
Power Sharing ◽  
Control Voltage ◽  
Droop Control ◽  
Reactive Power Control ◽  
Control Scheme ◽  
Static Performance ◽  
Virtual Flux

AbstractThis paper investigates the problem of reactive power sharing based on virtual flux droop method. Firstly, flux droop control method is derived, where complicated multiple feedback loops and parameter regulation are avoided. Then, the reasons for inaccurate reactive power sharing are theoretically analyzed. Further, a novel reactive power control scheme is proposed which consists of three parts: compensation control, voltage recovery control and flux droop control. Finally, the proposed reactive power control strategy is verified in a simplified microgrid model with two parallel DGs. The simulation results show that the proposed control scheme can achieve accurate reactive power sharing and zero deviation of voltage. Meanwhile, it has some advantages of simple control and excellent dynamic and static performance.

scholarly journals An Anti-Fluctuation Compensator Design and Its Control Strategy for Wind Farm System

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6413
Author(s):  
Feng-Chang Gu ◽  
Hung-Cheng Chen
Keyword(s):  
Power Control ◽  
Control Strategy ◽  
Large Scale ◽  
Wind Farm ◽  
Reactive Power ◽  
Wind Farms ◽  
Voltage Regulation ◽  
Current Control ◽  
Reactive Power Control ◽  
Control Scheme

Large-scale wind farms in commercial operations have demonstrated growing influence on the stability of an electricity network and the power quality thereof. Variations in the output power of large-scale wind farms cause voltage fluctuations in the corresponding electrical networks. To achieve low-voltage ride-through capability in a doubly fed induction generator (DFIG) during a fault event, this study proposes a real-time reactive power control strategy for effective DFIG application and a static synchronous compensator (STATCOM) for reactive power compensation. Mathematic models were developed for the DFIG and STATCOM, followed by the development of an indirect control scheme for the STATCOM based on decoupling dual-loop current control. Moreover, a real-world case study on a commercial wind farm comprising 23 DFIGs was conducted. The voltage regulation performance of the proposed reactive power control scheme against a fault event was also simulated. The simulation results revealed that enhanced fault ride-through capability and prompt recovery of the output voltage provided by a wind turbine generator could be achieved using the DFIG along with the STATCOM in the event of a three-phase short-circuit fault.

The Influence Analysis of Rectifier Side Control Mode on Commutation Failure in UHVDC

2014 ◽  
Vol 631-632 ◽  
pp. 339-344
Author(s):  
Jun Xiang Rong ◽  
Ju Rui Yang
Keyword(s):  
Power Control ◽  
Short Circuit ◽  
Transmission System ◽  
Current Control ◽  
Control Mode ◽  
Constant Current ◽  
Critical Voltage ◽  
Constant Power ◽  
Ground Fault ◽  
Commutation Failure

This paper studies the influence of different control modes in the rectifier side (constant current control, constant power control) on commutation failure in UHVDC transmission system. The study is based on Yunnan-Guangdong ±800kV UHVDC transmission system and simulated in PSCAD/EMTDC. A wealth of simulation results indicate that the control ability of the constant current control on commutation failure caused by the critical voltage ratio of inverter transformer increased is worse than the constant power control; the control ability of the constant current control on commutation failure caused by three-phase grounding fault happens at inverter side AC bus is worse than the constant power control; The control ability of the constant current control on commutation failure caused by phase to phase short circuit fault or single-phase ground fault happens at inverter side AC bus is worse than the constant power control.

scholarly journals A novel configuration and control of CSI wind energy system with diode rectifier and buck converter

2021 ◽  
Author(s):  
Xiatian Tan
Keyword(s):  
Wind Energy ◽  
High Power ◽  
Reactive Power ◽  
Current Source ◽  
Buck Converter ◽  
Operating Conditions ◽  
Direct Drive ◽  
Control Scheme ◽  
Dc Current ◽  
And Control

This thesis is dedicated to the research of a new converter configuration and control scheme development for direct drive permanent magnet synchronous generator (PMSG) based high power wind energy conversion system (WECS). The proposed converter consists of a diode rectifier, a buck converter and a pulse-width modulated (PWM) current source inverter (CSI). Detailed feasibility study of the proposed configuration is conducted based on the theoretical analysis. A suitable control scheme is designed to optimize the system performance. The maximum power point tracking (MPPT) is achieved through duty cycle adjustment of the buck converter, while the reactive power delivery and the DC current regulation are realized by the CSI controller through manipulating modulation index and delay angle. More importantly, the DC current is evaluated and controlled to the minimum value at various operating conditions. Simulation of a 2 MW WECS is carried out in Matlab/Simulink to verity the control objectives of MPPT, power factor adjustment and DC current minimization. The simulation results prove the feasibility of the proposed system that serves as an attracting alternative for high power WECS.

scholarly journals A novel configuration and control of CSI wind energy system with diode rectifier and buck converter

2021 ◽  
Author(s):  
Xiatian Tan
Keyword(s):  
Wind Energy ◽  
High Power ◽  
Reactive Power ◽  
Current Source ◽  
Buck Converter ◽  
Operating Conditions ◽  
Direct Drive ◽  
Control Scheme ◽  
Dc Current ◽  
And Control

This thesis is dedicated to the research of a new converter configuration and control scheme development for direct drive permanent magnet synchronous generator (PMSG) based high power wind energy conversion system (WECS). The proposed converter consists of a diode rectifier, a buck converter and a pulse-width modulated (PWM) current source inverter (CSI). Detailed feasibility study of the proposed configuration is conducted based on the theoretical analysis. A suitable control scheme is designed to optimize the system performance. The maximum power point tracking (MPPT) is achieved through duty cycle adjustment of the buck converter, while the reactive power delivery and the DC current regulation are realized by the CSI controller through manipulating modulation index and delay angle. More importantly, the DC current is evaluated and controlled to the minimum value at various operating conditions. Simulation of a 2 MW WECS is carried out in Matlab/Simulink to verity the control objectives of MPPT, power factor adjustment and DC current minimization. The simulation results prove the feasibility of the proposed system that serves as an attracting alternative for high power WECS.

scholarly journals Constant-Current Gate Driver for GaN HEMTs Applied to Resonant Power Conversion

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2377
Author(s):  
Héctor Sarnago ◽  
Óscar Lucía ◽  
Iulian O. Popa ◽  
José M. Burdío
Keyword(s):  
High Performance ◽  
Cost Effective ◽  
Current Control ◽  
Operating Conditions ◽  
Constant Current ◽  
Efficient Operation ◽  
Zero Voltage Switching ◽  
Resonant Inverter ◽  
Wide Range ◽  
Gate Driver

New semiconductor technology is enabling the design of more reliable and high-performance power converters. In particular, wide bandgap (WBG) silicon carbide (SiC) and gallium nitride (GaN) technologies provide faster switching times, higher operating temperature, and higher blocking voltage. Recently, high-voltage GaN devices have opened the design window to new applications with high performance and cost-effective implementation. However, one of the main drawbacks is that these devices require accurate base current control to ensure safe and efficient operation. As a consequence, the base drive circuit becomes more complex and the final efficiency is decreased. This paper presents an improved gate driver circuit for GaN devices based on the use of a constant current regulator (CCR). The proposed circuit achieves constant current regardless of the operating conditions, solving variations with temperature, aging and operating conditions that may degrade the converter performance. Besides, the proposed circuit is reliable and cost-effective, being applicable to a wide range of commercial, industrial and automotive applications. In this paper, its application to a zero-voltage switching resonant inverter for domestic induction heating was performed to prove the feasibility of this concept.

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