scholarly journals DFIG use with combined strategy in case of failure of wind farm

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.

Author(s):  
Alex Reis ◽  
Leandro Pains Moura ◽  
José Carlos de Oliveira

AbstractThe ever-growing demand for energy sources of low environmental impact has given a greater importance to wind farms in many countries. However, due to operational characteristics of these complexes, which are reflected into a variability of the energy produced and in the use of power electronic converters, the interaction between wind power plants and electrical networks shows itself to be an area of high investigative interest. In fact, among the various phenomena that exist, steady state voltage variations constitute a theme that is under the constant attention of electrical system operators. In this context, the present article is directed toward the analysis of a voltage regulation strategy aimed at wind power generation systems composed by synchronous machines and full converters. Once established the methodology that lead to an ancillary operation of the wind farm, the authors present results of computational simulations on ATP/EMTP platform that attest to the efficiency of the strategy.


2021 ◽  
Vol 4 (2) ◽  
pp. 33
Author(s):  
Jannatul Mawa Akanto ◽  
Md. Rifat Hazari ◽  
Mohammad Abdul Mannan

According to the grid code specifications, low voltage ride-through (LVRT) is one of the key factors for grid-tied wind farms (WFs). Since fixed-speed wind turbines with squirrel cage induction generators (FSWT-SCIGs) require an adequate quantity of reactive power throughout the transient period, conventional WF consisting of SCIG do not typically have LVRT capabilities that may cause instability in the power system. However, variable-speed wind turbines with doubly fed induction generators (VSWT-DFIGs) have an adequate amount of LVRT enhancement competency, and the active and reactive power transmitted to the grid can also be controlled. Moreover, DFIG is quite expensive because of its partial rating (AC/DC/AC) converter than SCIG. Accordingly, combined installation of both WFs could be an effective solution. Hence, this paper illustrated a new rotor-side converter (RSC) control scheme, which played a significant role in ensuring the LVRT aptitude for a wide range of hybrid WF consisting of both FSWT-SCIGs and VSWT-DFIGs. What is more, the proposed RSC controller of DFIG was configured to deliver an ample quantity of reactive power to the SCIG during the fault state to make the overall system stable. Simulation analyses were performed for both proposed and traditional controllers of RSC of the DFIG in the PSCAD/EMTDC environment to observe the proposed controller response. Overall, the presented control scheme could guarantee the LVRT aptitude of large-scale SCIG.


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.


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4291
Author(s):  
Paxis Marques João Roque ◽  
Shyama Pada Chowdhury ◽  
Zhongjie Huan

District of Namaacha in Maputo Province of Mozambique presents a high wind potential, with an average wind speed of around 7.5 m/s and huge open fields that are favourable to the installation of wind farms. However, in order to make better use of the wind potential, it is necessary to evaluate the operating conditions of the turbines and guide the independent power producers (IPPs) on how to efficiently use wind power. The investigation of the wind farm operating conditions is justified by the fact that the implementation of wind power systems is quite expensive, and therefore, it is imperative to find alternatives to reduce power losses and improve energy production. Taking into account the power needs in Mozambique, this project applied hybrid optimisation of multiple energy resources (HOMER) to size the capacity of the wind farm and the number of turbines that guarantee an adequate supply of power. Moreover, considering the topographic conditions of the site and the operational parameters of the turbines, the system advisor model (SAM) was applied to evaluate the performance of the Vestas V82-1.65 horizontal axis turbines and the system’s power output as a result of the wake effect. For any wind farm, it is evident that wind turbines’ wake effects significantly reduce the performance of wind farms. The paper seeks to design and examine the proper layout for practical placements of wind generators. Firstly, a survey on the Namaacha’s electricity demand was carried out in order to obtain the district’s daily load profile required to size the wind farm’s capacity. Secondly, with the previous knowledge that the operation of wind farms is affected by wake losses, different wake effect models applied by SAM were examined and the Eddy–Viscosity model was selected to perform the analysis. Three distinct layouts result from SAM optimisation, and the best one is recommended for wind turbines installation for maximising wind to energy generation. Although it is understood that the wake effect occurs on any wind farm, it is observed that wake losses can be minimised through the proper design of the wind generators’ placement layout. Therefore, any wind farm project should, from its layout, examine the optimal wind farm arrangement, which will depend on the wind speed, wind direction, turbine hub height, and other topographical characteristics of the area. In that context, considering the topographic and climate features of Mozambique, the study brings novelty in the way wind farms should be placed in the district and wake losses minimised. The study is based on a real assumption that the project can be implemented in the district, and thus, considering the wind farm’s capacity, the district’s energy needs could be met. The optimal transversal and longitudinal distances between turbines recommended are 8Do and 10Do, respectively, arranged according to layout 1, with wake losses of about 1.7%, land utilisation of about 6.46 Km2, and power output estimated at 71.844 GWh per year.


Author(s):  
E. Muljadi ◽  
C. P. Butterfield

Wind power generation has increased very rapidly in the past few years. The total U.S. wind power capacity by the end of 2001 was 4,260 megawatts. As wind power capacity increases, it becomes increasingly important to study the impact of wind farm output on the surrounding power networks. In this paper, we attempt to simulate a wind farm by including the properties of the wind turbine, the wind speed time series, the characteristics of surrounding power network, and reactive power compensation. Mechanical stress and fatigue load of the wind turbine components are beyond the scope this paper. The paper emphasizes the impact of the wind farms on the electrical side of the power network. A typical wind farm with variable speed wind turbines connected to an existing power grid is investigated. Different control strategies for feeding wind energy into the power network are investigated, and the advantages and disadvantages are presented.


2016 ◽  
Vol 10 (8) ◽  
pp. 1
Author(s):  
Faraz Chamani ◽  
Mohammad Satkin

Wind energy is one of the extraordinary sources of renewable energy due to its clean character and free availability. With increase in wind power penetration, the wind farms are directly influencing the power systems. The majority of wind farms are using variable speed wind turbines equipped with doubly fed induction generators (DFIG) due to their advantages over other wind turbine generators (WTGs). Therefore, the analysis of wind power dynamics with the DFIG wind turbines has become a very important research issue, especially during transient faults. In this article, a controller is provided to control the active and reactive power of a wind system equipped with doubly fed induction generator. The generator is connected to the grid by a back to back converter that gets benefit from control system known as single periodic controller. Grid and generator side converters respectively control the generator speed and reactive power using proposed controller. In order to increase the accuracy of controller, we optimized its PI parameters using genetic optimization algorithm. Finally, simulation results conducted by the MATLAB software are shown. The results of simulation gained through this system, show the capability of proposed controller under error conditions for controlling active and reactive power and also elimination of harmonics caused by non-linear load.


2011 ◽  
Vol 347-353 ◽  
pp. 2342-2346
Author(s):  
Rong Fu ◽  
Bao Yun Wang ◽  
Wan Peng Sun

With increasing installation capacity and wind farms penetration, wind power plays more important role in power systems, and the modeling of wind farms has become an interesting research topic. In this paper, a coherency-based equivalent model has been discussed for the doubly fed induction generator (DFIG). Firstly, the dynamic models of wind turbines, DFIG and the mechanisms are briefly introduced. Some existing dynamic equivalent methods such as equivalent wind model, variable speed wind turbine model, parameter identification method and modal equivalent method to be used in wind farm aggregation are discussed. Then, considering wind power fluctuations, a new equivalent model of a wind farm equipped with doubly-fed induction generators is proposed to represent the interactions of the wind farm and grid. The method proposed is based on aggregating the coherent group wind turbines into an equivalent one. Finally, the effectiveness of the equivalent model is demonstrated by comparison with the wind farm response obtained from the detailed model. The dynamic simulations show that the present model can greatly reduce the computation time and model complexity.


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 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.


2013 ◽  
Vol 278-280 ◽  
pp. 1427-1431 ◽  
Author(s):  
Lei Tian ◽  
Tong Wang ◽  
Ya Miao

In recent years, with the increasing of wind farm's capacity, requirements of the ability of fault ride through for wind farm are getting more and more stringent. The article analyzes the methods improving the low voltage ride through capability of the constant speed constant frequency wind power generation system. Static Synchronous Compensator (STATCOM) and Series Dynamic Breaking Resistor (SDBR) have recently been reported as stabilization methods for fixed-speed wind generator systems. Simulation results demonstrate that the STATCOM is a cost-effective solution for transient stability enhancement and minimization of voltage fluctuations, while the BR is the simplest in structure and a cost-effective solution for transient stability enhancement. Then a method is prompted, which Combines STATCOM and SDBR to promote the fault ride-through ability of constant speed constant frequency wind power system. By this way, the system validity and stability can be improved while costs can be cut down.


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