scholarly journals A novel current controller design for grid-integrated PV inverter system

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Ayaz Ahmad ◽  
L. Rajaji ◽  
A. Iqbal
Keyword(s):  
Controller Design ◽  
Vital Role ◽  
Current Feedback ◽  
Lcl Filter ◽  
Design Algorithm ◽  
Grid Voltage ◽  
Pv Inverter ◽  
Current Controller ◽  
Experimental Implementation ◽  
Grid Connected Inverter

AbstractDistributed generators are playing a vital role in supporting the grid in ever-increasing energy demands. Grid code regulation must be followed when integrating the photovoltaic inverter system to the grid. The paper investigates and analyzes a controller model for grid-connected PV inverters to inject sinusoidal current to the grid with minimum distortion. To achieve better tracking and disturbance rejection, a DSP-based current controller is designed with LCL filter. The controller gets the current feedback from the grid, compares it with reference current, and calculates duty cycle to generate PWM pulses to trigger H-bridge converters. The grid voltage is loaded to the initial value in proposed PR controller to ensure the initial inverter voltage to match the grid voltage. The paper presents a novel current controller algorithm for grid-connected inverter system, and simulation is done. A detailed analysis has been carried out to validate the proposed design algorithm. Experimental implementation of the current controller in the DC/AC converter circuits with an LCL filter is done for 5.4 kW to validate and match the simulation model.

scholarly journals An Optimal Current Controller Design for a Grid Connected Inverter to Improve Power Quality and Test Commercial PV Inverters

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Ali Algaddafi ◽  
Saud A. Altuwayjiri ◽  
Oday A. Ahmed ◽  
Ibrahim Daho
Keyword(s):  
Controller Design ◽  
Harmonic Distortion ◽  
Switching Frequency ◽  
Resistive Load ◽  
Lcl Filter ◽  
Fast Fourier Transform Analysis ◽  
Pv Inverter ◽  
Grid Connection ◽  
Current Controller ◽  
Grid Connected Inverter

Grid connected inverters play a crucial role in generating energy to be fed to the grid. A filter is commonly used to suppress the switching frequency harmonics produced by the inverter, this being passive, and either an L- or LCL-filter. The latter is smaller in size compared to the L-filter. But choosing the optimal values of the LCL-filter is challenging due to resonance, which can affect stability. This paper presents a simple inverter controller design with an L-filter. The control topology is simple and applied easily using traditional control theory. Fast Fourier Transform analysis is used to compare different grid connected inverter control topologies. The modelled grid connected inverter with the proposed controller complies with the IEEE-1547 standard, and total harmonic distortion of the output current of the modelled inverter has been just 0.25% with an improved output waveform. Experimental work on a commercial PV inverter is then presented, including the effect of strong and weak grid connection. Inverter effects on the resistive load connected at the point of common coupling are presented. Results show that the voltage and current of resistive load, when the grid is interrupted, are increased, which may cause failure or damage for connecting appliances.

scholarly journals Discrete-Time DC-Link Voltage and Current Control of a Grid-Connected Inverter with LCL-Filter and Very Small DC-Link Capacitance

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5613 ◽  
Author(s):  
Oliver Kalmbach ◽  
Christian Dirscherl ◽  
Christoph M. Hackl
Keyword(s):  
Discrete Time ◽  
Controller Design ◽  
Linear Quadratic Regulator ◽  
Current Control ◽  
Control Loop ◽  
Linear Quadratic ◽  
Lcl Filter ◽  
Current Controller ◽  
Voltage Controller ◽  
Grid Connected Inverter

The paper presents a controller design for grid-connected inverters (GCI) with very small dc-link capacitance that are coupled to the grid via an LCL filter. The usual controller designs would fail and result in instability. The proposed controller has a cascaded structure with a current controller as inner control loop and an outer dc-link voltage controller. The controller design is performed in discrete time and it is based on a detailed stability analysis of the dc-link voltage controller to determine the controller parameters which guarantee stability for all operating points. The inner loop is a state-feedback current controller that is designed based on the discrete linear-quadratic regulator (DLQR) theory. An additional integral error feedback assures steady-state accuracy of the current control loop. The simulation and experimental results validate performance and stability of proposed controller design.

scholarly journals Deadbeat Current Controller Design for Multilevel Grid Connected Inverter

2016 ◽  
Vol 100 ◽  
pp. 237-242 ◽  
Author(s):  
Yousry Atia ◽  
Mahrous Ahmed ◽  
Aref Eliwa ◽  
Mahmoud Salem
Keyword(s):  
Controller Design ◽  
Current Controller ◽  
Grid Connected Inverter

The Analysis of the Grid-Connected Phase-Locked Loop Technologies Based on the Transformation of Coordinate System

2012 ◽  
Vol 220-223 ◽  
pp. 1175-1180
Author(s):  
Guo Tao Yang ◽  
Zhi Yi Sun ◽  
Li Qun Liu
Keyword(s):  
Simulation Analysis ◽  
Phase Locked Loop ◽  
Phase Voltage ◽  
Grid Voltage ◽  
Advantages And Disadvantages ◽  
Pv Inverter ◽  
Three Phase ◽  
Failure Conditions ◽  
Grid Connected Inverter ◽  
Generating System

In order to gain the same amplitude、frequency and phase between the output voltage of the inverter and the grid voltage, the phase-locked loop (PLL) technology is widely used in grid-connected photovoltaic (PV) generating system, which is normally used to obtain instantaneous phase information to achieve the grid-connected purpose of PV inverter. The detective accuracy of frequency and phase of the grid voltage is directly affected by the PLL. Two software PLL technologies are compared by using the simulation analysis which is based on the d-q transformation. To provide the basis for the design of grid-connected inverter, the advantages and disadvantages of two software PLL technologies are analyzed under different grid failure conditions, such as one phase voltage dropped, two of three phase voltage (TPV) dropped, grid frequency mutated, and grid voltage offset, etc. Particularly, the appropriate PLL technology can effectively improve the grid-connected ability of PV inverter under the grid voltage offset or unbalance conditions.

scholarly journals Grid Voltage Estimation Based on Integral Resonant Current Controller for LCL-Filtered Grid-Connected Inverter without AC Voltage Sensors

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2051
Author(s):  
Thuy Vi Tran ◽  
Kyeong-Hwa Kim
Keyword(s):  
Phase Angle ◽  
Sensorless Control ◽  
State Observer ◽  
Current Control ◽  
Grid Voltage ◽  
Current Controller ◽  
Start Up ◽  
Control Scheme ◽  
Full State ◽  
Grid Connected Inverter

A high reliability of a grid-connected inverter (GCI) system at reasonable cost is a critical requirement for maximizing renewable energy potential in the electrical energy market. Several grid voltage sensorless control approaches have been investigated not only to eliminate the vulnerability of faulty sensors but also to further reduce the GCI commercial price. In this paper, a frequency adaptive integral-resonant full-state feedback current control scheme with the facilitation of a full-state observer is adopted for a grid-connected inductive–capacitive–inductive (LCL) filtered inverter without sensing the grid voltages. The proposed scheme actively damps the filter resonance and ensures the robustness of the inverter system against unexpected severe grid conditions with low cost and simplified hardware construction. The synchronization of the inverter with the main grid is accomplished by the proposed current controller-based grid voltage estimator, in which the grid frequency and phase angle can be detected effectively. In addition, the actual grid voltages are precisely regenerated to ensure the stable performance of the full-state observer. A safe start-up procedure is also presented for the grid voltage sensorless control of the LCL-filtered inverter to avoid a critical overcurrent and long settling time during the start-up instant, offering a stable and reliable inverter system operation with low computational burden. The effectiveness and feasibility of the proposed voltage sensorless current control scheme are validated by the simulation and experimental results under non-ideal grid conditions such as the harmonic distortion, grid frequency variation, and sudden grid phase angle jump.

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