scholarly journals Oscillation Suppression Method by Two Notch Filters for Parallel Inverters under Weak Grid Conditions

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3441 ◽  
Author(s):  
Ling Yang ◽  
Yandong Chen ◽  
Hongliang Wang ◽  
An Luo ◽  
Kunshan Huai
Keyword(s):  
Control Method ◽  
Harmonic Oscillation ◽  
Output Impedance ◽  
Notch Filters ◽  
Current Feedback ◽  
Weak Grid ◽  
Oscillation Suppression ◽  
In Series ◽  
Suppression Method ◽  
Grid Side

With plenty of parallel inverters connected to a weak grid at the point of common coupling (PCC), the impedance coupling interactions between the inverters and the grid are enhanced, which may cause high-frequency harmonic oscillation and further aggravate the system instability. In this paper, a basic technique for inverter output impedance is proposed to suppress the oscillation, showing that the inverter output impedance should be designed relatively high at the harmonic oscillation frequency, while relatively low at other frequencies. On the basis of the proposed technique, two virtual impedances are added to be in parallel and in series with the original inverter output impedance, respectively. Thus, an oscillation suppression method by two notch filters is proposed to realize the virtual impedances and increase the whole system damping. The implementation forms of the virtual impedances are presented by the proposed PCC voltage feedforward and grid-side inductor current feedback with two notch filters. Finally, simulation and experimental results are provided to verify the validity of the proposed control method.

scholarly journals Robust Grid-Current-Feedback Resonance Suppression Method for LCL-Type Grid-Connected Inverter Connected to Weak Grid

2018 ◽  
Vol 6 (4) ◽  
pp. 2126-2137 ◽  
Author(s):  
Xiaoping Zhou ◽  
Leming Zhou ◽  
Yandong Chen ◽  
Zhikang Shuai ◽  
Josep M. Guerrero ◽  
...  
Keyword(s):  
Current Feedback ◽  
Grid Current ◽  
Weak Grid ◽  
Suppression Method ◽  
Grid Connected Inverter

scholarly journals A Photo-Voltaic Invert-er Cluster Resonance Suppression Method Based on Capacitor Voltage Feed-Forward

2021 ◽  
Vol 2136 (1) ◽  
pp. 012012
Author(s):  
Shengqing Li ◽  
Xin Yao ◽  
Ziran Peng ◽  
Zhichao Shen
Keyword(s):  
Control Structure ◽  
System Control ◽  
Current Feedback ◽  
Lcl Filter ◽  
Feed Forward ◽  
Weak Grid ◽  
Capacitor Voltage ◽  
Simulation And Experiment ◽  
Suppression Method ◽  
Photo Voltaic

Abstract Photo-voltaic inverts usually use LCL filter for filtering, and LCL filter will bring resonance problems to the system. This paper focuses on invert-er side current feedback control (invert-er side current feedback, ICF). This paper proposes a method for suppressing resonance of photo-voltaic invert-er clusters based on capacitor voltage feed-forward. First, establish the ICF mathematical model based on HPF and CVF under the weak grid, qualitatively analyze the resonance mechanism of the cluster invert-er, then analyze the system control structure and stability according to the proposed method, and finally verify the effectiveness of the proposed method through simulation and experiment sexuality and correctness.

scholarly journals A Bio-Inspired Compliance Planning and Implementation Method for Hydraulically Actuated Quadruped Robots with Consideration of Ground Stiffness

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2838
Author(s):  
Xiaoxing Zhang ◽  
Haoyuan Yi ◽  
Junjun Liu ◽  
Qi Li ◽  
Xin Luo
Keyword(s):  
Harmonic Oscillation ◽  
Ground Surface ◽  
Legged Locomotion ◽  
Soft Ground ◽  
Quadruped Robots ◽  
In Series ◽  
Reaction Forces ◽  
Implementation Method ◽  
The Stability ◽  
Natural Dynamics

There has been a rising interest in compliant legged locomotion to improve the adaptability and energy efficiency of robots. However, few approaches can be generalized to soft ground due to the lack of consideration of the ground surface. When a robot locomotes on soft ground, the elastic robot legs and compressible ground surface are connected in series. The combined compliance of the leg and surface determines the natural dynamics of the whole system and affects the stability and efficiency of the robot. This paper proposes a bio-inspired leg compliance planning and implementation method with consideration of the ground surface. The ground stiffness is estimated based on analysis of ground reaction forces in the frequency domain, and the leg compliance is actively regulated during locomotion, adapting them to achieve harmonic oscillation. The leg compliance is planned on the condition of resonant movement which agrees with natural dynamics and facilitates rhythmicity and efficiency. The proposed method has been implemented on a hydraulic quadruped robot. The simulations and experimental results verified the effectiveness of our method.

scholarly journals Emulation of grid-forming inverters using real-time PC and 4-quadrant voltage amplifier

2021 ◽  
Author(s):  
Wolf Schulze ◽  
Maurizio Zajadatz ◽  
Michael Suriyah ◽  
Thomas Leibfried
Keyword(s):  
Real Time ◽  
Control Method ◽  
Current Control ◽  
Control Methods ◽  
Test Bed ◽  
Test Scenario ◽  
Power Semiconductors ◽  
Voltage Amplifier ◽  
Grid Side ◽  
Virtual Synchronous Machine

AbstractA test bed for the evaluation of novel control methods of inverters for renewable power generation is presented. The behavior of grid-following and grid-forming control in a test scenario is studied and compared.Using a real-time capable control platform with a cycle time of 50 µs, control methods developed with Matlab/Simulink can be implemented. For simplicity, a three-phase 4‑quadrant voltage amplifier is used instead of an inverter. Thus, the use of modulation and switched power semiconductors can be avoided. In order to show a realistic behavior of a grid-side filter, passive components can be automatically connected as L‑, LC- or LCL-filter. The test bed has a nominal active power of 43.6 kW and a nominal voltage of 400 V.As state-of-the-art grid-following control method, a current control in the d/q-system is implemented in the test bed. A virtual synchronous machine, the Synchronverter, is used as grid-forming control method. In combination with a frequency-variable grid emulation, the behavior of both control methods is studied in the event of a load connection in an island grid environment.

scholarly journals The experimental identification method of the dynamic efficiency for frequency regulation algorithms of AEDs

2021 ◽  
Vol 12 (1) ◽  
pp. 59 ◽  
Author(s):  
Vladimir L. Kodkin ◽  
Aleksandr S. Anikin
Keyword(s):  
Control Method ◽  
Frequency Control ◽  
Reference Signal ◽  
Frequency Regulation ◽  
Current Feedback ◽  
Electric Drives ◽  
Stator Current ◽  
Asynchronous Electric Drive ◽  
Input Side ◽  
Mechanical Moment

The article proposes and substantiates a method for studying the dynamics of an asynchronous electric drives with frequency control from the input side of the signal for setting the speed of rotation of the electric motor. In this method, a constant speed reference signal is added to a harmonic variable frequency signal. The set of amplitude changes and phase shifts of velocity oscillations are the initial data for identifying the dynamics of the studied control method. The logic of this method is determined by the previously obtained nonlinear transfer function of the link that forms the mechanical moment in the asynchronous electric drive with frequency control. Experiments have shown the dynamic benefits of the drive with positive stator current feedback.

scholarly journals MR Damper-Based Vibration Suppression Method for Control Moment Gyroscope

2018 ◽  
Vol 36 (5) ◽  
pp. 884-889
Author(s):  
Wendong Wang ◽  
Xing Ming ◽  
Yang Chu ◽  
Minghui Liu ◽  
Yikai Shi
Keyword(s):  
Active Control ◽  
Control Algorithm ◽  
Vibration Suppression ◽  
Control Method ◽  
Magnetorheological Damper ◽  
Magnetic Flux Density ◽  
Damping Force ◽  
Control Moment Gyroscope ◽  
Control Moment ◽  
Suppression Method

To restrain the interference of micro-vibration caused by Control Moment Gyroscope, a new control method based on Magnetorheological damper was proposed in this paper. A mechanical model based on the structure of the presented design was built, and the semi-active control algorithm of damping force was proposed for the designed Magnetorheological damper. The magnetic flux density and other magnetic field parameters were considered and analyzed in Maxwell, and also the related hardware circuit which implements the control algorithm was prepared to test the presented design and algorithm. The results of simulation and experiments show that the presented Magnetorheological damper model and semi-active control algorithm can complete the requirements, and the vibration suppression method is efficient for Control Moment Gyroscope.

scholarly journals Simulation of reactive power regulation of DFIG

2021 ◽  
Vol 233 ◽  
pp. 01025
Author(s):  
Yingfeng Zhu ◽  
Xiaosu Xie ◽  
Dong Yang ◽  
Song Gao ◽  
Weichao Zhang ◽  
...  
Keyword(s):  
Wind Farm ◽  
Reactive Power ◽  
Control Method ◽  
Power Regulation ◽  
Working Principle ◽  
Power Limit ◽  
Doubly Fed ◽  
Grid Side ◽  
Grid Side Converter ◽  
And Control

Doubly fed induction generator (DFIG) wind power generation system is widely used in wind farm all over the world. Reactive power can be generated both in grid-side converter and generator-side converter of DFIG. In this paper, working principle and control method of DFIG are introduced, and the reactive power limit of DFIG is derived, finally reactive power regulation is simulated in Simulink.

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