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.

Power Feedward Strategy of Grid-Connected Inverter Based on Direct Power Decoupling

2013 ◽  
Vol 331 ◽  
pp. 311-314
Author(s):  
Chun Peng Fu ◽  
Yong Qiang Zhu
Keyword(s):  
Output Power ◽  
Mathematic Model ◽  
Direct Power ◽  
Loop Control ◽  
Grid Voltage ◽  
Voltage Change ◽  
Power Decoupling ◽  
Grid Connected Inverter ◽  
The Relationship ◽  
Power Response

Take into account grid inverter that using direct power control is vulnerable to the disturbance of grid voltage, a control algorithm is proposed based on the relationship between the power and voltage, which is deduced according to the mathematic model of the inverter that using double-loop control strategy. The change amount of the output power of inverter is added to the reference of power closed-loop as power feedforward, which improves the dynamic response to the grid voltage change. Simulations with EMTDC/PSCAD are carried out and the comparison of output power response to grid voltage change between control with and without power feedforward verifies its effectiveness.

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.

DSP - Based Islanding Protection for Photovoltaic Grid Connected Inverter

2013 ◽  
Vol 291-294 ◽  
pp. 2007-2010
Author(s):  
Khanchai Tunlasakun
Keyword(s):  
Digital Signal Processor ◽  
Digital Signal ◽  
Local Load ◽  
Grid Voltage ◽  
National Instrument ◽  
Point Of Common Coupling ◽  
Common Coupling ◽  
Utility Grid ◽  
Grid Connected Inverter ◽  
Signal Processor

This research presents the DSP - based islanding protection for photovoltaic grid connected inverter with under / over frequency and under / over voltage islanding protection methods. The design is based on the TMS320VC33PGE digital signal processor on the NI SPEEDY 33 board from National Instrument Inc. The prototype is monitor the grid frequency and grid voltage at the point of common coupling (PCC) between the photovoltaic grid connected inverter, the local load and the distribution. The results of study, the prototype can turn off relay between photovoltaic grid connected inverter and utility grid when the frequency is change under 48Hz or over 52Hz and the voltage is change under 200V or over 240V.

Modified Power Compensation Control Strategy of Three-Phase Grid-Connected Inverter under Unbalanced Grid Voltage Conditions

2015 ◽  
Vol 740 ◽  
pp. 335-338 ◽  
Author(s):  
Shao Hua Sun ◽  
Hong Qi Ben
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Positive Sequence ◽  
Grid Voltage ◽  
Compensation Control ◽  
Active And Reactive Power ◽  
Three Phase ◽  
Grid Connected Inverter ◽  
Three Phase Inverter ◽  
Unbalanced Grid

Control strategy under unbalanced grid voltage conditions is one of the most important issues for grid-connected inverter. Under unbalanced grid voltage conditions, the 2nd active and reactive power ripples generate, they pollute the grid. To meet the demands of IEEE Std.929-2000, this paper proposed a modified power compensation control strategy; the proposed solution is based on direct power control. To provide accurate compensating power, the power model of three-phase inverter under unbalanced grid voltage conditions is given, using the positive sequence current component and the negative sequence voltage component, the compensating powers are calculated in details. Theoretical analysis and comparative simulation verification are presented to demonstrate the effectiveness of the proposed control strategy.

scholarly journals Coordinate Control of Power/Current for Grid-Connected Inverter Based on PCI Controller under Unbalanced Grid Conditions

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Chencong Zhao ◽  
Jun Liu ◽  
Zhouhua Xie ◽  
Feihang Zhou
Keyword(s):  
Output Power ◽  
Control Strategy ◽  
Balance Control ◽  
Weight Coefficient ◽  
Current Harmonics ◽  
Coordinate Control ◽  
Harmonic Components ◽  
Grid Connected Inverter ◽  
Complex Integral ◽  
Unbalanced Grid

The oscillations on output power and distortion of the inverter currents will occur in the case of unbalanced grid voltage faults. Constant output power and good current quality cannot be achieved simultaneously. Aiming at these problems, a coordinate control strategy for suppressing power fluctuations and current harmonics is proposed by analyzing instantaneous power control and current balance control. The proposed control is achieved by adjusting the weight coefficient of current reference values to change the current harmonic contents based on proportional complex integral (PCI) controller and proportional multiple complex integral (PMCI) controller. The control strategy with a simple control structure neither needs to detect harmonic components of the inverter currents, nor needs to separate the positive and negative components of voltage and current, which is easy to be realized. The feasibility and effectiveness of the proposed control are verified by the comparison and analysis of simulation.

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