جستجوی مقالات مرتبط با کلیدواژه "doubly-fed induction generator" در نشریات گروه "برق"

Due to the ever-increasing development of the electricity industry and the growth of consumption demand, the use of clean energy sources is increasing. In this regard, the use of wind energy as a clean and free source for the production of electrical energy is expanding day by day, and according to predictions, 20% of the world's energy will be obtained through wind by 2030. But in addition to all the advantages of wind energy, using them in the form of wind turbines in power grids in order to provide the required power can be considered a negative factor from the point of view of stability in power systems. The purpose of this article is to use the predictive control method based on logger functions to check the small signal stability of a hybrid network, including synchronous generators, wind farms and parallel STATCOM compensator. In this method, by using logger functions, the computational time in model-based predictive control has been reduced, so that the accuracy of tracking control signals can be increased and the stability of the system can be improved. The proposed method for controlling the active and reactive powers in the rotor side converter related to DFIG and the type of compensator used has been done in such a way that the performance of the power system can be increased by applying appropriate switching in the corresponding inverter. The simulation results using MATLAB software have been evaluated in the time domain, and its superiority has been clearly shown in order to improve the damping of power system fluctuations.

In the event of voltage sag at the nearing of a wind park, severe currents may pass through the power electronic devices of the Doubly Fed Induction Generators (DFIGs). Hence, according to the Low Voltage Ride Through (LVRT) requirements, the wind parks are allowed to disconnect from the network after a certain time. Therefore, to avoid such actions, the LVRT requirement of wind parks is considered to be enhanced in this paper. This aim is achieved by offering a novel objective function in order to find the optimum impedance of Superconducting Fault Current Limiter (SFCL). To evaluate the effectiveness of the proposed method, it is verified in MATLAB/SIMULINK and its great performance to amend the LVRT of such wind parks is corroborated by the simulation results.

In this paper, a sliding mode controller with an adjustable reactive power reference value is proposed. To improve the performance of the controller in a steady-state, an Integral Sliding Mode Control is designed and used. In addition, to improve the low-voltage ride-through capability in the fault condition, a reactive power controller with an adjustable reference value is proposed. The performance of this control system, during the power track, is compared with two other control systems that have a fixed reference for reactive power and are based on SMC and PI controllers in 9 different fault modes. These 9 different modes include one-phase, two-phase, and three-phase short circuit faults in the sub-synchronous, synchronous, and super-synchronous mode of operation for DFIG. The proposed method has been implemented in Simulink/MATLAB software. The simulation results confirm the capability and effectiveness of the proposed control system in comparison with two other aforementioned control systems.

As the penetration of wind power into the power system has increased in recent years, the importance of transient behavior analysis of wind turbine generators is felt more than ever, especially during network faults. Among the various types of generators which are used in wind power plants, studying the behavior of Doubly fed induction generator (DFIG) as the most well-known generator in the wind power industry is so important. This Paper uses a detailed model of grid-connected DFIG appropriate for fault analysis. This model includes a  order mathematical model of the wound rotor induction machine along with a two-mass model of the mechanical drive train. In the next step, transient fault responses of DFIG based wind turbine are analyzed by using simulation results from the MATLAB/Simulink software. Further examinations are also made to verify the impact of various parameters of wind turbine-generator system on fault ride-through (FRT) capability of grid-connected DFIG.

The paper presents an optimal and coordinated power oscillation damper based on a wind turbine and power system stabilizer (PSS) to maintain the power system stability and damp inter-area oscillations. The optimal and coordinated design of the PSS located at the generator site and the damper which was installed in the control section of the doubly-fed induction generator (DFIG) is defined as an optimization problem and simulations have been performed in MATLAB software environment. To determine optimal coefficients of the PSS and damper, the metaheuristic salp swarm optimization (SSA) algorithm was employed with an objective function that aimed to minimize the error caused by frequency deviations of two areas. Due to the use of wide-area measurement systems (WAMS) in the proposed damper to enhance controllability and observability of most of the oscillation modes, time delays resultant from the WAMS was also taken into account. Additionally, uncertainties of wind intermittency and time delay of WAMS were calculated probabilistically. The suggested method was applied to a six-machine two-area power system with a wind farm. The obtained simulation results highlighted and validated the superior performance and stability of the power system as a result of using the proposed method.

The stator of the doubly-fed induction generator-based wind turbine is connected directly to the grid, which makes possible reactive power compensation of the grid. In this paper, controlling reactive power in DFIG in two modes, the first assumption is neglecting stator resistance while the second one is considering stator resistance and its flux variations in four performance modes including maximum stator reactive power absorption, maximum stator reactive power generation, mode minimum casualties and minimization modes are provided. For each mode in each of assumptions and optimization problem introduced and PSO algorithm utilized to find a feasible solution. By solving the optimization problems with aim of PSO algorithm, the required for controlling reactive power in each mode is achieved. To demonstrate the efficiency of proposed method, the results compared with another method based on an iterative algorithm. Simulation results show that considering linkage flux variations of stator as a constraint of the optimization problems has led to good performance in controlling reactive power of DFIG.

This paper addresses the improvement of active and reactive power control in a multi-machine system using battery energy storage system, frequency control, and voltage regulation simultaneously. In the proposed method, each wind unit is equipped with an exclusive storage unit with a control system. This method for battery energy storage system includes two decoupled control loops-- one loop for active power control and the other loop for the reactivation of power control. In addition, there are two supplementary control loops for frequency control and voltage regulation in the rotor side converter of each generator. Besides, the proposed control strategy, here, optimally tunes all the parameters of controllers have been optimized simultaneously by utilizing a mixed integer nonlinear optimization programming by ICA and GA algorithm. The simulation results carried out from MATLAB software show the effectiveness not only of the proposed control scheme in utilizing battery energy storage system in the control of the active and reactive power of the wind assortment but also of the strategy in balanced and unbalanced conditions of the networks.

Grid code compatibility of HVDC interfaced offshore wind farm is evaluated in this paper. DC coupling causes power system contingencies not to get reflected in the offshore wind farm. In this regard, DC link voltage level is modulated to reflect the status of the onshore power system. Accordingly, onshore power system contingencies are reflected in the offshore wind farm by means of DC link voltage measurement and appropriate exercise of the wind farm HVDC converter. It is to excite dynamic frequency response and Low Voltage Ride Through (LVRT) capabilities of the modern wind turbines. A unified control structure is also proposed for doubly fed induction generator-based offshore wind farms that can model and compare three communication based, frequency modulation based, and voltage modulation based LVRT approaches. Moreover, a hybrid frequency and voltage modulation based approach is proposed in which an appropriate discrimination is embedded between fast transients related to LVRT condition and slow transients related to frequency contingencies. Accordingly, voltage modulation and frequency modulation approaches are utilized under LVRT and frequency events respectively. Simulation results have revealed similar dynamic frequency response capability for all four approaches. Moreover, except frequency modulation approach, remaining approaches have been able to fulfill grid code requirements given agile communication speed. It is concluded that the proposed hybrid frequency and voltage modulation, as the superior approach, has advantages like minimum LVRT DC voltage profile increase and subsequent deviation from theoperating point after the fault and preservation of conventional control structure thanks to appropriate dissociation between slow and fast dynamics.

In this paper, the modal analysis of a grid connected doubly-fed induction generator (DFIG) using small signal stability analysis is presented and effect of variation in system parameters such as mutual inductance, stator resistance, line reactance, shaft stiffness and wind speed on the eigenvalues, stability and damping ratio of different modes of system are studied. This analysis shows that which parameters variation can deviate the system from normal working conditions as well as which parameters variation can improve the system behavior. For evaluating the stability and different controllers design, the simulation results show the effects of parameters variations.