Grid voltage sags control strategy for photovoltaic inverter based on adaptive dynamic reactive power compensation

2015 ◽  
Author(s):  
Xiaolin Zhang ◽  
Jingsheng Huang ◽  
Fei Zheng ◽  
Junjun Zhang
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Reactive Power Compensation ◽  
Voltage Sags ◽  
Grid Voltage ◽  
Adaptive Dynamic

Improving Active Output Capacity of Large-Scale Wind Farm by Installation STATCOM

2012 ◽  
Vol 588-589 ◽  
pp. 574-577 ◽  
Author(s):  
Yan Juan Wu ◽  
Lin Chuan Li
Keyword(s):  
Control Strategy ◽  
Large Scale ◽  
Wind Farm ◽  
Transient Stability ◽  
Reactive Power ◽  
Feedforward Control ◽  
Wind Farms ◽  
Active Power ◽  
Utilization Efficiency ◽  
Grid Voltage

Some faults will result wind turbine generators off-grid due to low grid voltage , furthermore, large-scale wind farms tripping can result in severe system oscillation and aggravate system transient instability . In view of this, static compensator (STATCOM) is installed in the grid containing large-scale wind farm. A voltage feedforward control strategy is proposed to adjust the reactive power of STATCOM compensation and ensure that the grid voltage is quickly restored to a safe range. The mathematical model of the doubly-fed induction wind generator (DFIG) is proposed. The control strategy of DFIG uses PI control for rotor angular velocity and active power. 4-machine system simulation results show that the STATCOM reactive power compensation significantly improve output active power of large-scale wind farm satisfying transient stability, reduce the probability of the tripping, and improve the utilization efficiency of wind farms.

A Novel Performance Enhancement Scheme for Doubly-Fed Induction Generator-Based Wind Power Systems under Voltage Sags and Swells

2017 ◽  
Vol 18 (4) ◽  
Author(s):  
Tapash Das ◽  
Jingxin Zhang ◽  
Hemanshu Pota
Keyword(s):  
Power Systems ◽  
Wind Power ◽  
Power Management ◽  
Reactive Power ◽  
Performance Enhancement ◽  
Protection System ◽  
Voltage Sags ◽  
Grid Voltage ◽  
Wind Power Systems ◽  
Doubly Fed

AbstractWind power is a major contributor in the renewable energy sector but it faces some issues regarding modern grid-code compliance. Popular wind power systems based on Doubly-Fed Induction Generators (DFIG) need additional protection under grid voltage disturbances. They also need to support the grid voltage under such transient occurrences. This paper presents a novel performance enhancement scheme for DFIGs subjected to symmetrical and asymmetrical voltage sags and swells at the Point of Common Coupling (PCC). The scheme comprises a protection system and a reactive power management system working simultaneously under the command of a supervisory control system. The protection system protects the DFIG converter by limiting the overcurrent in the Rotor Side Converter (RSC) of the DFIG and keeping the dc-link capacitor voltage within an acceptable range; whereas, the reactive power management supports the grid voltage by either injecting or absorbing reactive power to reduce the magnitude of voltage sags and swells. It is found that the performance of the DFIG wind generation system improves significantly under the proposed scheme. A grid-connected 9-MW DFIG wind farm is used for simulation in MATLAB/Simscape Power Systems.

Analysis on Power Output Capability and its Power Control Strategy of DFIG Wind Turbine under Unbalanced Grid Voltage

2013 ◽  
Vol 448-453 ◽  
pp. 1819-1824
Author(s):  
Shu Ju Hu ◽  
Ling Ling Wang ◽  
Ya Deng
Keyword(s):  
Power Control ◽  
Wind Turbine ◽  
Control Strategy ◽  
Power Output ◽  
Reactive Power ◽  
Maximum Output ◽  
Voltage Sags ◽  
Active And Reactive Power ◽  
Unbalanced Voltage ◽  
Power Limit

Wind turbines are required by gird codes that active and reactive power should be fed into power grid during gird faults such as voltage sags. Power output capability is important for DFIG wind turbine to provide active and reactive power support. Constraints of stator, rotor maximum current and maximum output voltage of rotor-side converter (RSC) of DFIG are considered to analyze stator power output limit of the DFIG under unbalanced voltage sags, and newton-raphson method is used to solve the power limits, then the power control strategy based on power limit analysis is proposed. Simulation, calculation and comparison are carried out by a 1.5MW DFIG wind turbine model, and the effectiveness of the analysis and the proposed control strategy is verified.

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.

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.

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