Using Dynamic Reactive Power Compensation Equipments to Enhance Low Voltage Ride-Through Capability of Fixed Speed Asynchronous Wind Farms

2013 ◽  
Vol 291-294 ◽  
pp. 481-489 ◽  
Author(s):  
Yu Lin Hu ◽  
Lei Shi ◽  
Hao Ming Liu

This paper presents wind energy conversion model, drive shaft’s dual-mass model and generator’s transient mathematical model for the transient analysis of fixed speed asynchronous wind generators, and analyzes the transient characteristics of the wind generators under the condition of low voltage fault. The control principles of two dynamic reactive power compensation equipments as static var compensator (SVC) and static synchronous compensator (STATCOM) are introduced. Take a wind farm consists of fixed speed asynchronous wind generators as an example, the two compensation equipments are simulated in PowerFactory/DIgSILENT to compare the effort of them on enhancing the low voltage ride-through capability of the wind farm.

2013 ◽  
Vol 724-725 ◽  
pp. 619-622 ◽  
Author(s):  
Chia Yu Hsu ◽  
Ta Hsiu Tseng ◽  
Pei Hwa Huang

The main purpose of this paper is to study the enhancement of the Low-Voltage-Ride-Through (LVRT) capability of the wind farm with the installment of the Static Synchronous Compensator (STATCOM) and the Static Var Compensator (SVC). With more penetration of wind energy from on-shore and off-shore wind farms, utilities have been starting to set up the regulation requiring the wind turbine generators to remain connected to the grid when a fault takes place in the system which is referred to as Low-Voltage-Ride-Through (LVRT). A wind farm composed with doubly fed induction generators is used as the study system. Both the STATCOM and the SVC are utilized as the devices for enhancing the LVRT capability of the wind farm. The results are demonstrated for comparing the performance of the two devices in the improvement of voltage dynamic characteristics of the study system.


2013 ◽  
Vol 756-759 ◽  
pp. 4171-4174 ◽  
Author(s):  
Xiao Ming Wang ◽  
Xing Xing Mu

With the Asynchronous wind generators as research object, this paper analyzes the problems of the voltage stability and the generation mechanism of the reactive power compensation during the wind farms connected operation. For paralleling capacitor bank has shown obvious defects, therefore this paper employs dynamic reactive power compensation to improve reactive characteristics of grid-connected wind farms. With the influences of different wind disturbances and grid faults on wind farms, wind farm model is set up and dynamic reactive power compensation system and wind speeds are built in the Matlab/Simulink software, The simulation result shows that they can provide reactive power compensation to ensure the voltage stability of the wind farms. But STATCOM needs less reactive compensation capacity to make sure the voltage and active power approaching steady state before the faults more quickly, Therefore STATCOM is more suitable for wind farms connected dynamic reactive power compensation.


2016 ◽  
Vol 40 (6) ◽  
pp. 555-568 ◽  
Author(s):  
Ridha Karoui ◽  
Abdelkarim Aouiti ◽  
Maha Zoghlami ◽  
Faouzi Bacha

The static synchronous compensator is one of the FACTS (Flexible Alternating Current Transmission System) device capable of maintaining the stability of wind turbines during a sudden default. Among these faults, the voltage drops at the connection bus wind turbines. For this fault case, the static synchronous compensator intervenes by injection of the reactive power to compensate the voltage drop. In this article, as application case, we study the wind farm of Bizerte (north of Tunisia). This farm is composed of fixed speed aero-generators using squirrel cage induction generators. Our study begins with modeling the wind system. Next, we describe the technical requirements for connection of a wind energy system to the grid and outfit at the voltage dips (low-voltage ride through) according to STEG (Tunisian Company of Electricity and Gas). We also present the structure of static synchronous compensator. Finally, we present the simulation results of the wind farm under low-voltage ride through with and without static synchronous compensator.


2013 ◽  
Vol 380-384 ◽  
pp. 3051-3056 ◽  
Author(s):  
Xiao Dan Wu ◽  
Wen Ying Liu

In this paper, starting from the active network loss formulas and wind characteristics, it is pointed out the reactive power loss and reactive flow is the major impact of wind power integration on power system loss. The reactive power loss formulas of box-type transformer, main step-up transformer, wind farm collector line and connecting grid line are analyzed. Next the reactive power loss of transformer and transmission line is described in detail. Then put forward the loss reduction measures that installing SVC on the low voltage side of the main step-up transformer and making the doubly-fed wind generators send out some reactive power at an allowed power factor. Use the case of Gansu Qiaodong wind farm to verify the effectiveness of the proposed measures.


Author(s):  
Azeddine Loulijat ◽  
Najib Ababssi ◽  
Mohammed Makhad

In the wind power area, Doubly Fed Induction Generator (DFIG) has many advantages due to its ability to provide power to voltage and constant frequency during rotor speed changes, which provides better wind capture as compared to fixed speed wind turbines (WTs). The high sensitivity of the DFIG towards electrical faults brings up many challenges in terms of compliance with requirements imposed by the operators of electrical networks. Indeed, in case of a fault in the network, wind power stations are switched off automatically to avoid damage in wind turbines, but now the network connection requirements impose stricter regulations on wind farms in particular in terms of Low Voltage Ride through (LVRT), and network support capabilities. In order to comply with these codes, it is crucial for wind turbines to redesign advanced control, for which wind turbines must, when detecting an abnormal voltage, stay connected to provide reactive power ensuring a safe and reliable operation of the network during and after the fault. The objective of this work is to offer solutions that enable wind turbines remain connected generators, after such a significant voltage drop. We managed to make an improvement of classical control, whose effectiveness has been verified for low voltage dips. For voltage descents, we proposed protection devices as the Stator Damping Resistance (SDR) and the CROWBAR. Finally, we developed a strategy of combining the solutions, and depending on the depth of the sag, the choice of the optimal solution is performed.


2011 ◽  
Vol 354-355 ◽  
pp. 989-992
Author(s):  
An Lin

Squirrel-cage induction generator (SCIG) has been widely utilized in large wind farms in China. However, the large wind farm composed of induction generators will cause obvious power system stability problems due to the dependency on reactive power. Doubly-fed induction generator (DFIG) has excellent dynamic characteristics of wind farm operations. With the increasing of wind power penetration in power systems, more and more wind farms use both SCIG and DFIG. This paper firstly analyzes the the dynamic characteristic of wind farm on power systems, especially in terms of the voltage stability. Then the interaction between the SCIGs and DFIGs is also investigated. A detailed simulation model of wind farms is presented by means of MATLAB. The simulation results demonstrate that the DFIG applications will improve the voltage stability of the wind farm largely and the low voltage ride through characteristics of SCIG to some extend.


2021 ◽  
Author(s):  
Miad Mohaghegh Montazeri

Using power electronic converters with reduced capacity in doubly-fed induction generator (DFIG) based wind turbines make them vulnerable to over-current during grid disturbances. This thesis aims to analyze the behaviour of doubly-fed induction generators based wind farm for various timing schemes of crowbar deactivation and resumption of rotor side converter (RSC) in the case of grid fault. Also, usage of a static synchronous compensator (STATCOM) for the purpose of stabilizing the grid voltage after a three-phase fault is studied in this these. Moreover, finding minimum capacity of STATCOM which ensures low-voltage ride through (LVRT) of wind farm is studied. Finally, coordination of reactive power from wind turbine generators and STATCOM in steady-state condition is performed. All the results in this thesis show that STATCOM improves low voltage ride through (LVRT) capability of wind farm and assists for an uninterrupted operation of wind turbine generators during grid faults.


Low voltage ride through capability is an ability of the wind farm to stay connected with grid at the time of disturbance in the power system. The penetration of wind based renewable energy resources is increasing and the low voltage ride through consideration is vital for systems studies. The literature available demonstrates the improvement in low voltage ride through either by using fault current limiters or by implementing a control strategy for induction generator based wind farms. In this paper the low voltage ride through capability enhancement of the fixed speed induction generator is presented with various fault current limiters. The authors have presented the effects of fault current limiters in the aggregated hybrid wind farm consisting the combination of fixed speed induction generators and doubly fed induction generators which is not available in literature so far. A transient fault is simulated using PSCAD/EMTDC software in both the cases and the results are presented and discussed.


2014 ◽  
Vol 25 (4) ◽  
pp. 128-135 ◽  
Author(s):  
Othman Hasnaoui ◽  
Mehdi Allagui

The main causes of wind farms disconnection from the grid is the three-phase grid faults at the point common coupling (PCC) e.g. the voltage dip. The use of a Static Synchronous Compensator (STATCOM) which is from the family of Flexible AC Transmission System (FACTS) devices can be used effectively in a wind park based on FSIG to provide transient voltage and to improve wind system stability. Due to the asynchronous operation nature, system instability of wind farms based on FSIG (Fixed Speed Induction Generator) is largely caused by the reactive power absorption by FSIG because due to the large rotor slip during grid fault. STATCOM contributes to control the grid voltage at PCC and maintain wind farm connection to the grid during some severe conditions of grid faults and used for power flow control and for damping power system oscillations. The evaluation of this control strategy using (STATCOM) is investigated in terms of regulation reactive power and transient stability of the wind farm during grid disturbances.


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