scholarly journals Modeling and Enhanced Error-Free Current Control Strategy for Inverter with Virtual Resistor Damping

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2499 ◽  
Author(s):  
Cheng Nie ◽  
Yue Wang ◽  
Wanjun Lei ◽  
Tian Li ◽  
Shiyuan Yin
Keyword(s):  
Design Method ◽  
Current Control ◽  
Simplified Model ◽  
Output Current ◽  
Control Precision ◽  
Harmonic Components ◽  
Grid Connected Inverter ◽  
Free Current ◽  
Output Filter ◽  
Compensation Design

In microgrid, the grid-connected inverter current with the LCL (inductor-capacitor-inductor) output filter is amplified at certain frequencies. Using virtual resistor damping method can help suppress the amplification. By choosing an appropriate virtual resistor value, the model of the inverter current control loop is simplified as a 2nd-order lowpass filter. Based on such simplified model, this paper proposes a design method of reference current compensation controller, which does not require decomposition of harmonic components. With the reference compensation, the inverter output current control precision is improved obviously. The simulation and experimental results verify the accuracy of the inverter simplified model and effectiveness of the reference compensation design method.

scholarly journals A Modified Grid-Connected Inverter Topology for Power Oscillation Suppression under Unbalanced Grid Voltage Faults

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5057
Author(s):  
Cheng Luo ◽  
Xikui Ma ◽  
Lihui Yang ◽  
Yongming Li ◽  
Xiaoping Yang ◽  
...  
Keyword(s):  
Output Power ◽  
Output Current ◽  
Grid Voltage ◽  
Power Oscillation ◽  
Power Simulation ◽  
Point Of Common Coupling ◽  
In Series ◽  
Grid Connected Inverter ◽  
Output Filter ◽  
Unbalanced Grid

Under unbalanced grid voltage faults, the output power oscillation of a grid-connected inverter is an urgent problem to be solved. In the traditional topology of inverters, it is impossible to eliminate power oscillation and simultaneously maintain balanced output current waveform. In this paper, considering the solvability of reference current matrix equation, the inherent mechanism of inverter output power oscillation is analyzed, and a modified topology with auxiliary modules inserted in series between the inverter output filter and the point of common coupling (PCC) is proposed. Due to the extra controllable freedoms provided by auxiliary modules, the inverter could generate extra voltage to correct PCC voltage while keeping balance of output current, so as to eliminate the oscillation of output power. Simulation and experimental results verify the effectiveness of the proposed topology.

scholarly journals Simulation of LLCL filter based on active damping weighted current control strategy

2021 ◽  
Vol 336 ◽  
pp. 01011
Author(s):  
Jiaxiong Zhu ◽  
Zhigang Xiao ◽  
Chang FENG
Keyword(s):  
Current Method ◽  
Current Control ◽  
Resonance Peak ◽  
Active Damping ◽  
Output Current ◽  
Core Component ◽  
Current Feedback ◽  
The Core ◽  
Grid Connected Inverter ◽  
Grid Side

Grid-connected inverters is the core component of distributed generation system, and the filter is the core component of the inverters. When the inverter works, the filter can effectively filter and suppress the high-frequency harmonics in the output current of the inverter side, so as to ensure the stability of the power grid and improve the working effect of the whole grid connected inverter system. The filter is a high order underdamped system, and the LLCL Filter also has a resonance peak. In this paper, a weighted current method based on active damping is used. In this method, the output current of the inverter side and the current of the grid side are weighted with a reasonable proportion as the feedback quantity, the weighted current feedback is the outer loop, and the LC series branch current feedback is the inner loop. The system is reduced to the first order theoretically, which makes up for the under damping problem of the system and suppresses the resonance peak of the system. Through the simulation experiment, the feasibility of the active damping weighted current method is verified.

scholarly journals Performance Improvement of a Grid-Connected Inverter under Distorted Grid Voltage Using a Harmonic Extractor

Electronics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1038
Author(s):  
Sungjoon Cho ◽  
Ho-Sung Kang ◽  
Kyo-Beum Lee ◽  
Ji-Yoon Yoo
Keyword(s):  
Control Strategy ◽  
High Harmonic ◽  
Harmonic Signal ◽  
Current Control ◽  
Grid Voltage ◽  
Current Controller ◽  
Synchronous Reference Frame ◽  
Distorted Grid ◽  
Harmonic Components ◽  
Grid Connected Inverter

This paper introduces an improved current control strategy for a grid-connected inverter system operating under distorted grid voltage conditions. Although existing current controllers for grid-connected inverters have proportional integral gains with suitable bandwidth, low-order harmonic components can be generated by distorted grid voltages. The proposed improved current controller is established in a synchronous reference frame that rotates at harmonic frequency. The input signals for the harmonic current controller should contain only the specific harmonic components requiring suppression. Therefore, the proposed current controller uses a harmonic extractor to distinguish current signals from fundamental and specific harmonic components. The harmonic extractor retains only the relevant harmonic components for individual current controllers with high harmonic signal ratios. This paper introduces two different strategies to extract specific harmonic components for the current controller. The proposed control strategy does not require any additional hardware filter circuits and can be implemented easily by designing a suitable digital filter. When using the proposed method, grid current quality is significantly improved compared to conventional methods that do not include harmonic extractors. The effectiveness of the proposed method is verified through simulations and practical experiments.

Development of an Induction-Free Current Sensor for Application in Spot-Welding Current Control

2012 ◽  
Vol 132 (1) ◽  
pp. 58-66
Author(s):  
Yoshiaki Takasaki ◽  
Tatsunori Munesada ◽  
Toshikatsu Sonoda
Keyword(s):  
Spot Welding ◽  
Welding Current ◽  
Current Control ◽  
Current Sensor ◽  
Free Current

scholarly journals A Decoupled Hybrid Current Control for Improving the Performance of 60° DPWM-Based Three-Phase Grid-Connected Inverter

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 876-888
Author(s):  
Yuanbin He ◽  
Bangchao Wang ◽  
Xiaogao Xie ◽  
Lei Shen ◽  
Pingliang Zeng
Keyword(s):  
Current Control ◽  
Three Phase ◽  
Grid Connected Inverter
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