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This paper analyses the rotor speed d-q mathematical model for brushless doubly-fed machine (BDFM). Applying stator flux-oriented vector control technology based on double synchronous reference frame, and adopting maximal wind energy capturing mechanism, the simulation model of BDFM wind generation system is obtained. To optimize the control scheme of the converter for the system, a voltage and current...
Since the doubly fed induction generator (DFIG) converters are designed by the slip power (a fraction 25-30% of the total power) to achieve full control of the generator, there is not enough capacity to provide reactive power when the voltage dips below the tolerable grid voltage level at the point of common coupling (PCC). We propose in this paper to use the static synchronous compensator (STATCOM)...
The amount of electricity generated by wind power converters is world wide steadily growing. In many countries it has become a political and public interest to support this development. From the wind park owner side of view it is of essential interest to generate and sell as much electricity as possible. With increasing shares of wind energy in the electrical power supply, their influence on the mains...
Machine speed is usually required for maximum power point tracking (MPPT) control of permanent-magnet synchronous generators (PMSG). In this paper, a sensorless control method is applied to the PMSG for micro wind turbine systems. The machine speed is estimated by using a rotor flux observer and induced EMF signal, which can solve the delay problem of the estimated speed. For vector control of PMSG...
Wind energy will play a very important role in the future electrical power supply. With growing shares, the focus of the plant control will have to shift from maximum power yield to also meet grid friendly aspects, like stable power output. This paper analyses the influence of wind energy converter controls on the plants behaviour. Three conventional controls and a new control approach, the stochastic...
The output power of wind turbines fluctuates due to wind speed variations. These power fluctuations make the wind power undispatchable, causing frequency deviations and power outage when wind power penetration is significant. Energy storage devices such as batteries, ultracapacitors, super inductors and flywheels can be utilized in a hybrid system to solve this problem. Although these methods are...
The increasing penetration level of wind farms in power system network requires better understanding of short-term voltage stability and ride through capability before their interconnection to grid. The future wind turbines must stay connected irrespective of any type of disturbance in grid. To achieve reliable operation and control, the wind turbines must be actively controlled in order to meet the...
This paper analyses the influence of different wind energy converter control methods on the connected electrical grid. As the wind energy propagates through the converter to the mains, their frequency components are influenced by the conversion processes. The plant control strategies have a major influence on these components. Especially frequencies between 2 Hz and 8 Hz can cause undesired flicker...
The reactive power demand of the induction generator is significantly increased when the generator runs close to the rated operating point. The losses are increased due to the increased reactive power flow. Due to the limitation of converter ratings in the doubly fed induction generator (DFIG) system, power clipping may occur at turbine-rated conditions. In this paper, an optimum strategy for reactive...
This paper introduces an improved strategy to increase the power production of wind turbines equipped with doubly fed induction generators (DFIGs) at low wind speed operation. The performance of DFIG-based wind turbines at low wind speeds, close to the cut in speed, is investigated. A modified control to extend the concept of maximum wind power tracking to cover the low wind speed region is implemented...
The recent development of power electronic technology encourages to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG) for wind power generation. Among those, stability analysis of DFIG type of VSWT has already been reported in many literatures. On the other hand, stability...
In wind electrical energy generating systems, due to fast voltage and current fluctuations, the power converter represents a source of electromagnetic disturbances. EMI problems of stand alone wind generators are here analysed in order to take into account many different power quality problems which result in voltage fluctuations and harmonics in the net. This paper, moreover, presents a wind turbine...
This paper details the modeling, controller development, simulation and analysis of an integrated 2MW variable-speed Wind Energy Conversion and Storage System (WECSS) in dynamic simulation software PSCAD. The WECSS presented consists of a pitch controlled wind turbine directly driving a 2MW permanent magnet synchronous generator (PMSG). The PMSG is connected to its host power system via a controlled...
Strong growth figures prove that wind is now a mainstream option for new power generation. However, wind stochasticity results in fluctuations in output power as well as undesirable dynamic loading of the drive-train during high turbulence. To provide industry with the support it needs to develop technologies capable of cost-effective operation, advanced power electronic components have become increasingly...
Depending on wind speed, a doubly fed induction generator (DFIG) based variable speed wind turbine is capable of operating in sub- or super-synchronous mode of operation using a back to back PWM converter. A smooth transition between these two modes of operation is necessary for reliable operations of the wind turbine under fluctuating wind. This paper presents the analysis and modeling of DFIG based...
This paper proposes numerical grey relational analysis (NGRA) based sensorless controllers for a small wind generation system. The maximum power of wind-turbine generator varies with the wind speed. Optimal wind energy extraction is operated in variable-speed variable-frequency model. The sensorless control strategies consist of two NGRAs for maximum power extraction. The first NGRA is used the generator...
In this work, the control of a Doubly fed induction machine using an indirect matrix converter, connected between the stator and the rotor, is presented. Unlike the traditional scheme, where two back-to-back PWM inverters are used, this converter eliminates the use of bulky DC link capacitors and provides an all silicon solution for direct AC-AC conversion, with sinusoidal input currents and close...
Stochastically fluctuating wind energy density has major influence on wind energy converters performance. Dynamic power flow variations in the power drain of wind energy converters lead, among others, to dynamical torque changes. Through the power drain, the load peaks are fed forward to the electrical grid and cause early damage of mechanical components, thermal overload of electrical components,...
This paper presents a control technique to maximize the output power of a wind turbine by adjusting the rotor speed. The control method is applied to a Doubly-fed induction generator (DFIG). The modeling of DFIG is performed using Matlab/Simulink. The wind speed is modeled based on Kaimal spectra. Since DFIG is a variable speed generator, the rotor speed can be regulated using the power electronics...
With rapid development of wind power technologies and significant growth of wind power capacity installed worldwide, various wind generator systems have been developed and built. The objective of this paper is to evaluate various wind generator systems by optimization designs and comparisons. In this paper, seven variable speed constant frequency (VSCF) wind generator systems are investigated, namely...
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