scholarly journals An Improved Droop Control Strategy for Grid-Connected Inverter Applied in Grid Voltage Inter-Harmonics and Fundamental Frequency Fluctuation

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1827
Author(s):  
Wanwan Xu ◽  
Bin Wang ◽  
Jiang Liu ◽  
Da Li
Keyword(s):  
Fundamental Frequency ◽  
Control Strategy ◽  
Negative Impact ◽  
Low Complexity ◽  
Frequency Fluctuation ◽  
Droop Control ◽  
Grid Voltage ◽  
Frequency Detection ◽  
Distorted Grid ◽  
Grid Connected Inverter

This paper presents a current suppression method based on a droop control strategy under distorted grid voltage with inter-harmonics and fundamental frequency fluctuation. In this proposed strategy, the current incomplete derivation controller is employed to decrease the negative impact caused by harmonic and inter-harmonic grid voltage. This method provides a good dynamic response and has low complexity against the inter-harmonics with unfixed fundamental frequency. Based on a mathematical model of the grid-connected inverter, we designed novel instantaneous frequency detection and feed-forward methods to suppress the grid fundamental frequency fluctuation impacts. Then the main parameters were analyzed. The simulation and experimental results verified the feasibility and effectiveness of the proposed method.

Control for Grid Connected Inverter under Unbalanced Grid Voltage Based on PI-QR Controller

2014 ◽  
Vol 716-717 ◽  
pp. 1648-1653
Author(s):  
Jia Jin Pan ◽  
Yan Cheng Liu ◽  
Chuan Wang ◽  
Qin Jin Zhang
Keyword(s):  
Reference Frame ◽  
Control Strategy ◽  
Control Model ◽  
Grid Voltage ◽  
Synchronous Reference Frame ◽  
Distorted Grid ◽  
Control Scheme ◽  
Grid Connected Inverter ◽  
Typical Model ◽  
Unbalanced Grid

Control strategy under unbalanced and distorted grid voltage is one of the most significant tasks for grid-connected inverter (GCI). In order to guarantee that the grid current meets the related IEEE Std.929-2000, a new control scheme was presented. Firstly, the typical model of GCI was presented. Secondly, the GCI control model based on PI-QR controller in synchronous reference frame (SRF) was built. Finally, the system’s simulation was conducted under distorted and unbalanced grid voltage. The results demonstrate the effectiveness of the presented control strategy.

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.

Research on Control Method of Grid-Connected Inverter Suppressing Grid-Voltage Background Harmonics

2013 ◽  
Vol 787 ◽  
pp. 861-866
Author(s):  
Chun Long Zhang
Keyword(s):  
Theoretical Analysis ◽  
Control Method ◽  
Original System ◽  
Resonance Phenomenon ◽  
Order System ◽  
Passive Damping ◽  
Grid Voltage ◽  
Distorted Grid ◽  
Forward Function ◽  
Grid Connected Inverter

The traditional LCL-filter third-order system grid-connected inverter may cause the resonance phenomenon without damping. Also, it will be affected by the distorted grid-voltage background harmonics. In order to overcome these problems, based on the passive damping method, a new control strategy is proposed. The paper analyses the current waveform performance of grid-connected inverter in the condition of grid-voltage background harmonics, derives the feed-forward function for grid-connected inverter. The disadvantages of passive damping could be well solved by damping resistor virtualization of the original system, which realized the active damping suppression of resonance. Simulation results based on the Heric single-phase transformerless grid-connected inverter verify the correctness of the 2éQ: theoretical analysis"theoretical analysis.

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