Control Strategy of Low Voltage Ride-Through for Grid-Connected Photovoltaic Power System Based on Predictive Current

2014 ◽  
Vol 556-562 ◽  
pp. 1753-1756
Author(s):  
Ming Guang Zhang ◽  
Xiao Jing Chen
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Photovoltaic System ◽  
Stable Operation ◽  
Voltage Sags ◽  
Low Voltage Ride Through ◽  
Pv Inverter ◽  
Current Instruction ◽  
Voltage Recovery

The control strategy based on predictive current is proposed to solve problems that destruct stable operation of grid-connected photovoltaic system during asymmetrical fall. A mathematical model of PV inverter is established to calculate current instruction; a method of tracking based on predictive current is proposed to reduce the fluctuations of 2 times frequency. In the meantime, PV inverter provides reactive power to support voltage recovery according to the depth of grid voltage sags and realize LVRT. The result also shows that the proposed control strategy can reduce wave of DC voltage and provide reactive power to support voltage recovery.

scholarly journals Modeling and Design of the Vector Control for a Three-Phase Single-Stage Grid-Connected PV System with LVRT Capability according to the Spanish Grid Code

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2899 ◽  
Author(s):  
Alexis B. Rey-Boué ◽  
N. F. Guerrero-Rodríguez ◽  
Johannes Stöckl ◽  
Thomas I. Strasser
Keyword(s):  
Vector Control ◽  
Reactive Power ◽  
Low Voltage ◽  
Single Stage ◽  
Photovoltaic System ◽  
Lookup Table ◽  
Voltage Sags ◽  
Pv System ◽  
Low Voltage Ride Through ◽  
Three Phase

This article deals with the vector control in dq axes of a three-phase grid-connected photovoltaic system with single-stage topology and low-voltage-ride-through capability. The photovoltaic generator is built using an array of several series-parallel Suntech PV modules and is modeled as a Lookup Table (two-dimensional; 2-D). The requirements adopted when grid voltage sags occur are based in both the IEC 61400-21 European normative and the allowed amount of reactive power to be delivered according to the Spanish grid code, which avoids the disconnection of the inverter under grid faults by a limitation in the magnitude of the three-phase output inverter currents. For this, the calculation of the positive- and negative-sequences of the grid voltages is made and a conventional three-phase Phase-Locked Loop is used for the inverter-grid synchronization, allowing the control of the active and reactive powers solely with the dq components of the inverter currents. A detailed enhanced flowchart of the control algorithm with low-voltage-ride-through capability is presented and several simulations and experiments using Matlab/SIMULINK and the Controller Hardware-in-the-Loop simulation technique, respectively, are run for several types of one- and three-phase voltage sags in order to validate its behavior.

scholarly journals Control Strategy of Three-Phase Photovoltaic Inverter under Low-Voltage Ride-Through Condition

2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
Xianbo Wang ◽  
Zhixin Yang ◽  
Bo Fan ◽  
Wei Xu
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Drop ◽  
Stable Operation ◽  
Power Fluctuation ◽  
Negative Sequence ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Grid Side

The new energy promoting community has recently witnessed a surge of developments in photovoltaic power generation technologies. To fulfill the grid code requirement of photovoltaic inverter under low-voltage ride-through (LVRT) condition, by utilizing the asymmetry feature of grid voltage, this paper aims to control both restraining negative sequence current and reactive power fluctuation on grid side to maintain balanced output of inverter. Two mathematical inverter models of grid-connected inverter containing LCL grid-side filter under both symmetrical and asymmetric grid are proposed. PR controller method is put forward based on inverter model under asymmetric grid. To ensure the stable operation of the inverter, grid voltage feedforward method is introduced to restrain current shock at the moment of voltage drop. Stable grid-connected operation and LVRT ability at grid drop have been achieved via a combination of rapid positive and negative sequence component extraction of accurate grid voltage synchronizing signals. Simulation and experimental results have verified the superior effectiveness of our proposed control strategy.

scholarly journals Low-voltage ride-through for a three-phase four-leg photovoltaic system using SRFPI control strategy

2019 ◽  
Vol 9 (3) ◽  
pp. 1524
Author(s):  
Haval Sardar Kamil ◽  
Dalila Mat Said ◽  
Mohd Wazir Mustafa ◽  
Mohammad Reza Miveh ◽  
Nasarudin Ahmad
Keyword(s):  
Control Strategy ◽  
Power Plants ◽  
Low Voltage ◽  
Photovoltaic System ◽  
Electrical Grid ◽  
Low Voltage Ride Through ◽  
Power Stations ◽  
Pv Inverter ◽  
Synchronous Reference Frame ◽  
Three Phase

With the innovative progresses in power electronics in recent years, photovoltaic (PV) systems emerged as one of the promising sources for electricity generation at the distribution network. Nonetheless, connection of PV power plants to the utility grid under abnormal conditions has become a significant issue and novel grid codes should be recommend. The low-voltage ride-through (LVRT) capability is one of the challenges faced by the integration of PV power stations into electrical grid under abnormal conditions. This work firstly provides a discussion on recent control schemes for PV power plants to enhance the LVRT capabilities. Next, a control scheme for a three-phase four-leg grid-connected PV inverter under unbalanced grid fault conditions using synchronous reference frame proportional integral (SRFPI) controller is proposed. Simulation studies are performed to investigate the influence of the control strategy on the PV inverter.

Strategy for Reactive Control in Symmetrical Low Voltage Ride through of Photovoltaic System

2014 ◽  
Vol 602-605 ◽  
pp. 2820-2823
Author(s):  
Ju Bo Wang ◽  
Wen Li Xu ◽  
Wei Bao ◽  
Pan Zhang
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Photovoltaic System ◽  
Reactive Control ◽  
Low Voltage Ride Through ◽  
Power Decoupling ◽  
Simulation And Experiment ◽  
System Output ◽  
New Type

The active and reactive power decoupling control of photovoltaic system is analyzed in this paper. The DC-DC and DC-AC two level photovoltaic inverter model are built on the RTDS. A new type LVRT control strategy about photovoltaic system is proposed. In the symmetrical grid drop fault case, photovoltaic system output reactive power to support the grid voltage recovering and save reactive power equipment. The feasibility and effectiveness of the control strategy is verified by simulation and experiment on the RTDS.

Study on Transient Characteristic of the DFIG LVRT

2013 ◽  
Vol 791-793 ◽  
pp. 1832-1836
Author(s):  
Jian Hua Zhang ◽  
Rong Luan ◽  
Hao Ran Shen
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Sag ◽  
Voltage Sags ◽  
Doubly Fed Induction Generator ◽  
Low Voltage Ride Through ◽  
Harmonic Currents ◽  
Doubly Fed ◽  
Operation Characteristics

In order to analyze the operational capability of the low voltage ride through ( LVRT) of a gird-connected wind turbine with doubly fed induction generator (DFIG) effectively, it is necessary to evaluate operation characteristics of DFIG under a grid fault.By using the transient principle of the flux of stator and rotor, the expressions of transient currents of stator and rotor of DFIG are derived under the grid voltage sag. The transient process is analyzed by using the Matlab to derive the correctness of the expression. A control strategy is presented to eliminate harmonic currents by proposing the essential factors of over-current of stator and rotor. The output active power and reactive power are calculated by using the derived expression with different voltage sags. Based on the theoretical analysis, a DFIG is established to analysis the model of LVRT. Simulation results show that the control strategy is able to eliminate the harmonic currents and achieve the requirements of LVRT.

scholarly journals Multi level Transformer less PV Inverter with Reduced Switching Losses and Elimination of CM leakage Current

2020 ◽  
Vol 9 (11) ◽  
pp. 223-228
Keyword(s):  
Leakage Current ◽  
Low Voltage ◽  
Stable Operation ◽  
Efficient Operation ◽  
Low Voltage Ride Through ◽  
Point Tracking ◽  
Pv Inverter ◽  
Switching Losses ◽  
Power Point Tracking ◽  
Power Point

In order to have efficient operation of grid connected Photovoltaic (PV) inverter, the issue of leakage current must be completely eliminated. For this new transformerless multilevel inverter is proposed in this paper with (k-1) levels in which k denotes the number of switches. The inverter provides zero common mode leakage current and also capable of operating under half of rated PV voltage, hence make this proposed inverter topology as LVRT (low voltage ride through) capable. Different modes are employed for the stable operation of the proposed inverter with varying input PV voltage. Simulation work is carried out for three, five and seven level proposed inverter topologies in MATLAB/Simulink software which determines its maximum power point tracking performance. Here the THD (Total Harmonic Distortions) of 3, 5 and 7 levels are compared.

The Transient Characteristics Analysis of Doubly-Fed Induction Generator during the Asymmetric Voltage Sag

2014 ◽  
Vol 644-650 ◽  
pp. 3509-3514
Author(s):  
Jian Hua Zhang ◽  
Hao Ran Shen ◽  
Lei Ding ◽  
Chun Lei Dai
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Drop ◽  
Voltage Sag ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Double Frequency ◽  
Characteristics Analysis ◽  
Doubly Fed

In order to analyze the control strategy of the low voltage ride through (LVRT) of DFIG during the asymmetric voltage sag, it is necessary to analyze the transient performance of a DFIG during the asymmetric voltage sag. In this paper, analyzed the influence of the asymmetric grid voltage to DFIG and the analysis method of the asymmetric voltage sag, and on the basis of positive and negative sequence mathematical model, analyzed the composition of stator output active and reactive power under the condition of asymmetric grid voltage. And built a DFIG asymmetric voltage drop simulation model of 1.5MW in MATLAB/Simulink, the simulation results shows that the stator voltage, current, active power and reactive power all present a double frequency ripple during the asymmetric voltage sag, consistent with theoretical analysis. It can provide theoretical basis for double-fed motor control strategy of asymmetric LVRT.

scholarly journals Low-Voltage Ride-Through Operation of Grid-Connected Microgrid Using Consensus-Based Distributed Control

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2867 ◽  
Author(s):  
Woon-Gyu Lee ◽  
Thai-Thanh Nguyen ◽  
Hyeong-Jun Yoo ◽  
Hak-Man Kim
Keyword(s):  
Distributed Control ◽  
Reactive Power ◽  
Control Method ◽  
Low Voltage ◽  
Power Sharing ◽  
Consensus Algorithm ◽  
Stable Operation ◽  
Low Voltage Ride Through ◽  
Primary Layer ◽  
Secondary Layer

Since the penetration of distributed energy resources (DERs) and energy storage systems (ESSs) into the microgrid (MG) system has increased significantly, the sudden disconnection of DERs and ESSs might affect the stability and reliability of the whole MG system. The low-voltage ride-through (LVRT) capability to maintain stable operation of the MG system should be considered. The main contribution of this study is to propose a distributed control, based on a dynamic consensus algorithm for LVRT operation of the MG system. The proposed control method is based on a hierarchical control that consists of primary and secondary layers. The primary layer is in charge of power regulation, while the secondary layer is responsible for the LVRT operation of the MG system. The droop controller is used in the primary layer to maintain power sharing among parallel-distributed generators in the MG system. The dynamic consensus algorithm is used in the secondary layer to control the accurate reactive power sharing and voltage restoration for LVRT operation. A comparison study on the proposed control method and centralized control method is presented in this study to show the effectiveness of the proposed controller. Different scenarios of communication failures are carried out to show the reliability of the proposed control method. The tested MG system and proposed controller are modeled in a MATLAB/Simulink environment to show the feasibility of the proposed control method.

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