An optimal grid current control strategy with grid voltage observer (GVO) for LCL-filtered grid-connected inverters

2018 ◽  
Vol 13 (5) ◽  
pp. 777-784
Author(s):  
Xiaobo Dou ◽  
Yang Jiao ◽  
Kang Yang ◽  
Zaijun Wu ◽  
Wei Gu ◽  
...  
Keyword(s):  
Control Strategy ◽  
Current Control ◽  
Grid Voltage ◽  
Grid Current

Research of the Three-Phase PV Power Grid Inverter Based on PR Control Used in Biomedicine

2013 ◽  
Vol 634-638 ◽  
pp. 1392-1397
Author(s):  
Nai Bo Zhang ◽  
Hong Yu Shen ◽  
Shu Xin Yin ◽  
Yu Bo Duan ◽  
Sheng Nan Liu ◽  
...  
Keyword(s):  
Control Strategy ◽  
Current Control ◽  
Double Loop ◽  
Loop Current ◽  
Output Current ◽  
Grid Voltage ◽  
Grid Current ◽  
Three Phase ◽  
Pv Grid

In the process of Biomedicine PV Grid, in order not to affect the quality of the grid, must ensure that the output current of photovoltaic power generation system and grid voltage maintain a high degree of consistency in the frequency, phase and amplitude. In order to make the output current of PV Grid inverter to meet the relevant standard of the grid, the appropriate grid filter and control strategy is the key. In order to improve the quality of the grid current and reduce the pollution of the grid harmonic current on the grid, select the three-phase full-bridge inverter circuit with LCL filters. In the grid control strategy, select the double loop current control based on grid current and capacitance current, and introduce the PR control into the double loop control system, analyze that PR control can achieve zero steady state error tracking of grid sinusoidal reference current and anti-grid voltage disturbances. Make double loop current control and SVPWM control combined, and prove the stability of this method through the simulation experiment.

scholarly journals Overall Adaptive Controller Design of PMSG Under Whole Wind Speed Range: A Perturbation Compensation Based Approach

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 732 ◽  
Author(s):  
Jian Chen ◽  
Wenyong Duan ◽  
Xiaodong Yang ◽  
Lanhong Zhang ◽  
Yi Shan ◽  
...  
Keyword(s):  
Adaptive Control ◽  
Wind Speed ◽  
Control Strategy ◽  
Controller Design ◽  
Current Control ◽  
Parameter Uncertainties ◽  
Pitch Control ◽  
Grid Current ◽  
Wind Speeds ◽  
Speed Range

This paper proposes an adaptive overall control strategy of the permanent magnet synchronous generator-based wind energy conversion system (WECS) in the whole wind speed range. For the machine side, the maximum power point tracking (MPPT) operation is realized by stator current and mechanical rotation speed control under below-rated wind speeds. Under above-rated wind speeds, the extracted wind power is limited via pitch control. For the grid side, the reactive and active power injected into grid is regulated by DC-Link voltage and grid current control loop. In addition, under grid voltage dips, the pitch control is employed for limiting grid current and maintaining the DC-Link voltage around its rated value. The fault ride-through capability (FRTC) can be enhanced. The overall control strategy is based on perturbation estimation technique. A designed observer is used for estimating the perturbation term including all system nonlinearities, uncertainties and disturbances, so as to compensate the real perturbation. Then, an adaptive control for the original nonlinear system can be realized. The effectiveness of the proposed overall control strategy is verified by applying the strategy to a 2-MW WECS in MATLAB/Simulink. The results show that, compared with the feedback linearizing control (FLC) strategy and conventional vector control (VC) strategy, the proposed perturbation observer based adaptive control (PO-AC) strategy realizes the control objectives without knowing full state information and accurate system model, and improves the robustness of the WECS parameter uncertainties and FRTC.

A Control Method to Suppress Resonance and Improve Current Quality for Inverter System with LCL Filter

2014 ◽  
Vol 644-650 ◽  
pp. 3528-3533
Author(s):  
Yong Peng Lin ◽  
Shun Tao ◽  
Xiang Ning Xiao ◽  
Mei Rong Wu
Keyword(s):  
Control Method ◽  
Current Control ◽  
Utilization Efficiency ◽  
Control Effect ◽  
Lcl Filter ◽  
Loop Control ◽  
Grid Voltage ◽  
Grid Current ◽  
Differential Voltage ◽  
Grid Side

The LCL filter is easy to resonate, especially in the new energy power system with multiple inverters. The LCL filter resonant formulas are derived in this paper and a novel double closed loop control strategy combing with the structure of the LCL filter was proposed at the base on feedback of capacitor current as a result. In the control system, the inner loop feedback the first differential voltage of filter inductor at the grid side to damp the resonance and nature of first differential voltage of filter inductor is explained; the grid current outer loop achieves direct control of the grid current for high power factor and utilization efficiency. The simulation results show that the grid-side inductor voltage differential feedback control have a better current control effect both in the condition of the normal power grid voltage and distorted grid voltage, and the fluctuations of power and dc voltage are reduced.

Dual current control strategy to fulfill LVRT requirements in WECS

2014 ◽  
Vol 33 (5) ◽  
pp. 1665-1677 ◽  
Author(s):  
Matías Díaz ◽  
Roberto Cárdenas-Dobson
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Current Control ◽  
Power Delivery ◽  
Positive Sequence ◽  
Content Type ◽  
Grid Voltage ◽  
Signal Cancellation ◽  
Laboratory Prototype

Purpose – The purpose of this paper is to investigate a control strategy to fulfill low-voltage ride through (LVRT) requirements in wind energy conversion system (WECS). Design/methodology/approach – This paper considers an active front-end converter of a grid connected WECS working under grid fault conditions. Two strategies based on symmetrical components are studied and proposed: the first one considers control only for positive sequence control (PSC); the second one considered a dual controller for positive and negative sequence controller (PNSC). The performance of each strategy is studied on LVRT requirements fulfillment. Findings – This paper shows presents a control strategy based on symmetrical component to keep the operation of grid-connected WECS under unsymmetrical grid fault conditions. Research limitations/implications – This work is being applied to a 2 kVA laboratory prototype. The lab prototype emulates a grid connected WECS. Originality/value – This paper validate the PNSC strategy to LVRT requirements fulfillment by experimental results obtained for a 2 kVA laboratory prototype. PNSC strategy allows constant active power delivery through grid-voltage dips. In addition, the proposed strategy is able to grid-voltage support by injection of reactive power. Additional features are incorporated to PNSC: sequence separation method using delay signal cancellation and grid frequency identification using phase locked loop.

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