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.

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.

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.

A Improved LVRT Control Strategy Based on Active and Reactive Power for Direct-Drive PMSG Wind Generation System

2013 ◽  
Vol 732-733 ◽  
pp. 1184-1187
Author(s):  
Guo Liang Yang ◽  
Shuo Yang Liu ◽  
Xin Yan Chang ◽  
En Bei Zhang
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Low Voltage ◽  
Control Strategies ◽  
Synchronous Generator ◽  
Direct Drive ◽  
Pwm Inverter ◽  
Low Voltage Ride Through ◽  
Active And Reactive Power ◽  
Grid Side

The structure of the uncontrolled rectifier + Boost circuit + PWM inverter is taken for direct-drive permanent magnet synchronous generator (PMSG) wind-power system. on the basis of the analysis for two different traditional control strategies for the grid side converter, a new control strategy Based on active and reactive power for the low voltage ride through running is proposed and described in detail. The simulation results verify that the given control strategy can be better to provide a reliable guarantee for the system low voltage ride through capability and to provide some reference for the actual control system design.

Research on the Control Strategy of DFIG Grid Side Converter under Unbalanced Grid Voltage Conditions

2012 ◽  
Vol 260-261 ◽  
pp. 454-459
Author(s):  
Fei Song ◽  
Dan Zhu ◽  
Kan Tang ◽  
Xue Jing Liu
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Voltage Drop ◽  
Current Control ◽  
Transient Model ◽  
Grid Voltage ◽  
Doubly Fed ◽  
Grid Side ◽  
Grid Side Converter ◽  
The Impact

This paper studies on the electromagnetic transient model of doubly-fed wind turbine grid-side converter under the imbalanced grid condition. And on this basis, the paper analysis the impact of doubly-fed converter when grid voltage asymmetric drop. It puts forward a dual PLL and dual current control combination of doubly-fed converter grid side control strategy. This strategy achieves grid voltage positive and negative sequence fast separation when asymmetric grid voltage drop occur, achieves the active output power secondary fluctuate suppression under the imbalanced grid voltage condition, avoids DC voltage rise at the fault moment and also achieves converter reactive power support under the imbalanced grid fault. The simulation and experimental results show that the proposed control strategy is correct and with the application value of engineering

Comparative Study on Low Voltage Ride-Through Test Methods for Grid-Connected Photovoltaic Inverter

2014 ◽  
Vol 590 ◽  
pp. 495-499
Author(s):  
Wen Jin Wu ◽  
Jian Hui Su ◽  
Hai Ning Wang
Keyword(s):  
Large Scale ◽  
Low Voltage ◽  
Voltage Drop ◽  
Power Grid ◽  
Design For Test ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Technical Requirements ◽  
Test Platform ◽  
The Stability

The large scale photovoltaic plants have more effects on the stability of regional power grid with the rapid increase of photovoltaic generation ratio in some areas. According to the grid guideline, the photovoltaic inverter is required to maintain the running status even the grid voltage drops and needs to have the capability to contribute towards the stability of power grid voltage and to support the grid voltage ride through. To test the ability of photovoltaic inverter low voltage ride through (LVRT), the test platform to simulate all kinds of fault for voltage drop needs to be set up. By the low voltage through technical requirements, this paper puts forward three kinds of design for test platform and analyzes respective work principle and characteristics, in order to provide optimization solution for the low voltage ride through test work.

scholarly journals Modeling and Parameter Optimization of Grid-Connected Photovoltaic Systems Considering the Low Voltage Ride-through Control

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3972
Author(s):  
Li Wang ◽  
Teng Qiao ◽  
Bin Zhao ◽  
Xiangjun Zeng ◽  
Qing Yuan
Keyword(s):  
Parameter Optimization ◽  
Low Voltage ◽  
Power Grid ◽  
Current Loop ◽  
Stable Operation ◽  
Power Fluctuation ◽  
Grid Current ◽  
Low Voltage Ride Through ◽  
Dc Bus ◽  
Bus Voltage

The asymmetric faults often cause the power grid current imbalance and power grid oscillation, which brings great instability risk to the power grid. To address this problem, this paper presented a modeling and parameter optimization method of grid-connected photovoltaic (PV) systems, considering the low voltage ride-through (LVRT) control. The harmonics of the grid current under asymmetric faults were analyzed based on the negative-sequence voltage feedforward control method. The notch filter was added to the voltage loop to filter out the harmonic components of the DC bus voltage and reduce the harmonic contents of the given grid current value. The proportional resonant (PR) controller was added to the current loop. The combination of these two components could reduce the 3rd, 5th, and 7th harmonics of the grid current and the output power fluctuation. Then, the parameters of the inverter controller were identified by the adaptive differential evolution (ADE) algorithm based on the sensitivity analysis. The effectiveness of the proposed method was compared with two other strategies under the asymmetric grid faults. The suppression of DC bus voltage fluctuation, power fluctuation, and low-order harmonics of the grid current all had better results, ensuring the safe and stable operation of the PV plant under grid faults.

Study of Low Voltage Ride through in Photovoltaic Grid-Tied Inverter Based on Unsymmetrical Grid Voltage Fall

2014 ◽  
Vol 986-987 ◽  
pp. 1277-1281
Author(s):  
Tian Fa Liao ◽  
Yang Chun ◽  
Wen Si ◽  
Chang Wen Dong ◽  
Jia Xiang Xue
Keyword(s):  
Power Output ◽  
Low Voltage ◽  
Hardware Platform ◽  
Negative Sequence ◽  
Grid Voltage ◽  
Low Voltage Ride Through ◽  
Current Controller ◽  
Three Phase ◽  
Overall Efficiency ◽  
Negative Sequence Current

In this paper, 10KW three-phase three-level photovoltaic grid-tied inverter is applied as hardware platform. Considering the insufficiency of PV arrays power output and low overall efficiency due to grid voltage falls asymmetrically, P-R current controller is used to provide unsymmetrical positive and negative sequence current to the grid so that low voltage ride through (LVPT) in photovoltaic inverter can be achieved. Through the implement of experiments, it is well proved that the requirement of LVPT when the grid voltage falls asymmetrically can be met by applying the solution proposed in this paper.

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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