scholarly journals Methodology for Tuning MTDC Supervisory and Frequency-Response Control Systems at Terminal Level under Over-Frequency Events

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2807 ◽  
Author(s):  
Marta Haro-Larrode ◽  
Maider Santos-Mugica ◽  
Agurtzane Etxegarai ◽  
Pablo Eguia
Keyword(s):  
Frequency Response ◽  
Control Structure ◽  
Synchronous Generator ◽  
Order Type ◽  
Offshore Wind ◽  
Loop Control ◽  
Hierarchical Levels ◽  
Terminal Level ◽  
The Uk ◽  
Specific Implementation

This paper proposes a methodology for tuning a supervisory and frequency-response outer loop control system of a multi-terminal direct current (MTDC) grid designed to transmit offshore wind energy to an onshore AC grid, and to provide frequency support during over-frequency events. The control structure is based on a master–slave scheme and ensures the achievement of frequency response, with specific implementation of the UK national grid code limited-frequency sensitive (LFSM) and frequency-sensitive (FSM) modes. The onshore AC grid is modelled with an equivalent frequency-response model to simulate the onshore AC grid dynamics under frequency deviations. The main innovation of this paper is the development of a methodology for tuning simultaneously two hierarchical levels of a MTDC coordinated control structure, i.e., the MTDC supervisor, given by the active power set point for slave terminal, and the slope of frequency-response functions at onshore terminals. Based on these two hierarchical levels, different strategies are evaluated in terms of frequency peak reductions and change of the frequency order type. Moreover, tuning guidance is given when a different MTDC control structure or different synchronous generator characteristics of the onshore AC grid are considered.

scholarly journals Synchronous Generator Rectification System Based on Double Closed-Loop Control of Backstepping and Sliding Mode Variable Structure

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1832
Author(s):  
Jinfeng Liu ◽  
Xin Qu ◽  
Herbert Ho-Ching Iu
Keyword(s):  
Closed Loop ◽  
Control Structure ◽  
Low Voltage ◽  
Sliding Mode ◽  
Variable Structure ◽  
Synchronous Generator ◽  
Closed Loop Control ◽  
High Current ◽  
Loop Control ◽  
Sliding Mode Variable Structure

Low-voltage and high-current direct current (DC) power supplies are essential for aerospace and shipping. However, its robustness and dynamic response need to be optimized further on some special occasions. In this paper, a novel rectification system platform is built with the low-voltage and high-current permanent magnet synchronous generator (PMSG), in which the DC voltage double closed-loop control system is constructed with the backstepping control method and the sliding mode variable structure (SMVS). In the active component control structure of this system, reasonable virtual control variables are set to obtain the overall structural control variable which satisfied the stability requirements of Lyapunov stability theory. Thus, the fast-tracking and the global adjustment of the system are realized and the robustness is improved. Since the reactive component control structure is simple and no subsystem has to be constructed, the SMVS is used to stabilize the system power factor. By building a simulation model and experimental platform of the 5 V/300 A rectification module based on the PMSG, it is verified that the power factor of the system can reach about 98.5%. When the load mutation occurs, the DC output achieves stability again within 0.02 s, and the system fluctuation rate does not exceed 2%.

scholarly journals Adaptation of VSC-HVDC Connected DFIG Based Offshore Wind Farm to Grid Codes: A Comparative Analysis

2019 ◽  
Vol 8 (1) ◽  
pp. 91
Author(s):  
Seyed Saed Heidary Yazdi ◽  
Jafar Milimonfared ◽  
Seyed Hamid Fathi
Keyword(s):  
Comparative Analysis ◽  
Frequency Response ◽  
Wind Turbines ◽  
Wind Farm ◽  
Control Structure ◽  
Offshore Wind ◽  
Offshore Wind Farm ◽  
Grid Codes ◽  
Primary Frequency ◽  
Primary Frequency Response

Lack of synchronism between VSC-HVDC (Voltage Source Converter - High Voltage Direct Current) connected offshore wind farm and onshore grid leads to immunity of wind turbines to grid contingencies. Focusing on DFIG (Doubly Fed Induction Generator) based wind farms; this paper has presented a univalent control structure based on inertial and primary frequency response in which DC link voltage is utilized as synchronization interface. Based on the presented structure, four approaches based on the communication system, frequency, voltage and combined frequency and voltage modulation are utilized and compared to inform the onshore grid status to individual wind turbines. Considering Kondurs two area power system, results have revealed that all four approaches have similar ability (with negligible error) in offering inertial and primary frequency response to improve slow network oscillations. On the other hand, voltage and combined frequency and voltage modulation approaches have the ability to satisfy Fault Ride Through (FRT) requirements thanks to superior dynamics. However, communication and frequency modulation approaches lose that ability as communication and frequency measurement delays increase respectively. It has been concluded that combined frequency and voltage modulation, as the superior approach, has advantages like minimum FRT DC voltage profile increase and deviation from operating point after the fault, the minimum imposition of electrical and mechanical stress on DFIG and preservation of prevalent control structure thanks to appropriate dissociation between slow and fast dynamics.©2019. CBIORE-IJRED. All rights reservedArticle History: Received Dec 8th 2017; Received in revised form July 16th 2018; Accepted December 15th 2018; Available onlineHow to Cite This Article: Yazdi, S.S.H., Milimonfared, J. and Fathi, S.H. (2019). Adaptation of VSC-HVDC Connected DFIG Based Offshore Wind Farm to Grid Codes: A Comparative Analysis. Int. Journal of Renewable Energy Development, 8(1), 91-101.https://doi.org/10.14710/ijred.8.1.91-101

Multi-loop model-based control structure for robot manipulators

Robotica ◽  
2005 ◽  
Vol 23 (4) ◽  
pp. 491-499 ◽  
Author(s):  
Rafael Osypiuk ◽  
Bernd Finkemeyer ◽  
Friedrich M. Wahl
Keyword(s):  
Control Structure ◽  
Robot Manipulator ◽  
Loop Model ◽  
Loop Control ◽  
Model Based Control ◽  
Model Following Control ◽  
Model Following ◽  
Theoretical Assumptions ◽  
Quantitative Results ◽  
The Stability

Most nonlinear control concepts used in robotics are based on a more or less accurate inverse model of the robot. In contrast to this, the design and properties of a general $n$-loop control structure based on a divided forward model of the robot, the so-called multi-loop Model Following Control Structure ($n$-MFC), is presented in this paper. Its theoretical basics and its concept are explained. The stability and robustness of the proposed control structure is analyzed. The theoretical assumptions are verified in many experiments with a two-joint robot manipulator. Qualitative as well as quantitative results of the experiments are presented and discussed.

Community Benefits and UK Offshore Wind Farms: Evolving Convergence in a Divergent Practice

2021 ◽  
pp. 2150001
Author(s):  
John Glasson
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Host Community ◽  
Offshore Wind ◽  
Energy Industry ◽  
Offshore Wind Farms ◽  
Onshore Wind ◽  
Community Benefits ◽  
The Uk ◽  
Renewable Energy Industry

The Offshore Wind sector is a major, dynamic, and rapidly evolving renewable energy industry. This is particularly so in Europe, and especially in the UK. Associated with the growth of the industry has been a growth of interest in community benefits as voluntary measures provided by a developer to the host community. However, in many cases, and for some of the large North Sea distant offshore wind farms, the benefits packages have been disparate and pro rata much smaller than for the well-established onshore wind farm industry. However, there are signs of change. This paper explores the issues of community benefits for the UK offshore sector and evolving practice, as reflected in a macro study of the adoption of community benefits approaches across the industry. This is followed by a more in-depth micro- approach, which explores approaches that have been adopted in three case studies of recent OWF projects — Aberdeen, Beatrice and the Hornsea Array. Whilst there is still much divergence in practice, there are also examples of some convergence, and the development of a more replicable practice. Particularly notable is the adoption of annual community benefits funds, as the key element of community benefits schemes/agreements between developers, local authorities and local communities.

scholarly journals Decoupled Multi-Loop Robust Control for a Walk-Assistance Robot Employing a Two-Wheeled Inverted Pendulum

Machines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 205
Author(s):  
Fu-Cheng Wang ◽  
Yu-Hong Chen ◽  
Zih-Jia Wang ◽  
Chi-Hao Liu ◽  
Pei-Chun Lin ◽  
...  
Keyword(s):  
Robust Control ◽  
Transfer Function ◽  
Inverted Pendulum ◽  
Control Structure ◽  
Position Tracking ◽  
Loop Control ◽  
Wheeled Inverted Pendulum ◽  
Decoupled Control ◽  
Rotational Motions ◽  
Electrical Motors

This paper develops a decoupled multi-loop control for a two-wheeled inverted pendulum (TWIP) robot that can assist user’s with walking. The TWIP robot is equipped with two wheels driven by electrical motors. We derive the system’s transfer function and design a robust loop-shaping controller to balance the system. The simulation and experimental results show that the TWIP system can be balanced but might experience velocity drifts because its balancing point is affected by model variations and disturbances. Therefore, we propose a multi-loop control layout consisting of a velocity loop and a position loop for the TWIP robot. The velocity loop can adjust the balancing point in real-time and regulate the forward velocity, while the position loop can achieve position tracking. For walking assistance, we design a decoupled control structure that transfers the linear and rotational motions of the robot to the commands of two parallel motors. We implement the designed controllers for simulation and experiments and show that the TWIP system employing the proposed decoupled multi-loop control can provide satisfactory responses when assisting with walking.

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