Rishabh Dev Shukla

Voltage stability improvement in power systems using facts controllers: State-of-the-art review

Flexible AC Transmission Systems (FACTS) devices have been used in power systems since the 1970s for the improvement of its dynamic performance. This paper presents a review on the research and developments in the voltage stability improvement by using FACTS controllers. In this paper several technical issues related to FACTS installations have been highlighted and performance comparison of different FACTS controllers have been discussed. In addition, real-world installations and semiconductor technology development have been reviewed and summarized. This paper also includes the main causes of voltage instability and power scenario in India. In order to deal with the voltage stability problem, the solutions with FACTS-controllers provide voltage support and/or appropriately co-ordinated control actions. Authors strongly believe that this survey article will be very much useful to the researchers for finding out the relevant references in the field of voltage stability improvement by using FACTS controllers in power system environments.

Low voltage ride through (LVRT) ability of DFIG based wind energy conversion system II

Doubly Fed Induction Generators (DFIGs) are nowadays extensively used in variable speed wind power plants. Doubly fed induction generators (DFIG) offer many advantages such as reduced converter rating, low cost and reduced losses with an improved efficiency, easy implementation of power factor correction schemes, variable speed operation and four quadrants active and reactive power control capabilities. Due to variable speed operation total energy output is much more in case of DFIG based WECS so capacity utilization factor is improved and cost of per unit energy is reduced. But the main disadvantage of DFIG is that it is very sensitive to grid disturbance/fault, especially for the voltage dip. Since the doubly-fed induction generator (DFIG) has been widely used in wind energy conversion, the low voltage ride through (LVRT) technology of the DFIG has been investigated extensively in recent times. This paper focuses on the fault ride-through capability of doubly fed induction generator (DFIG) based WECSs Under three phase symmetrical fault. The paper also provides an overview on the interaction between variable-speed DFIG based WECSs and the power system subjected to three phase symmetrical fault. The Steady state behaviour under normal condition and dynamic behaviour of DFIG wind turbines during grid faults is simulated and assessed.

Power electronics applications in wind energy conversion system: A review

This paper gives a review on the power electronic applications for wind energy conversion systems. Different types of wind energy conversion system (WECS) with different generators and power electronic converters are described, and different technical features are compared. The electrical topologies of WECS with different wind turbines are summarized and the possible uses of power electronic converters with wind farms are given. In conclusion, the possible methods of using the power electronic technology for improving wind turbine performance in power systems to meet the main grid connection requirements are discussed.

Speed-sensorless voltage & frequency control in autonomous DFIG based wind energy systems

This paper investigates the application of the hysteresis current control technique to control the voltage and frequency of a variable speed-constant frequency autonomous DFIG based wind energy system by using Direct Voltage Control method. The DFIG feeds an isolated R-L load. A diode bridge rectifier and a power electronics converter (called rotor side converter) having common dc link is connected between the stator and rotor of the DFIG. The control strategy uses the speed-sensorless control for the rotor side converter designed for low-to-medium wind speeds. To regulate the voltage and frequency at stator terminals, the error between the actual rotor currents and the reference rotor currents is given to the hysteresis controller. The reference currents are obtained by the direct voltage control technique. The control pulses for the rotor side converter are supplied by the hysteresis controller which is operated on the error signal. A 2 MVA Wind energy system is designed by using DFIG prototype in MATLab/Simulink. Simulation outcome obtained from the 2 MVA system are presented and discussed in this paper.

A stand-alone Wind Energy Conversion System using wound rotor induction machine

A sensorless control method for standalone mode operation of doubly fed induction generator is presented. The generated stator voltage is controlled via rotor currents. The stator voltage amplitude of and its frequency are controlled independently. In order to control the amplitude & frequency of stator voltage in stand-alone DFIG based WECS the following studies were carried out, the study and simulation of a Standalone DFIG based Wind Energy Conversion System at constant wind speed was performed, then the transient study for sudden change in wind speed, was done and simulated, the performance of DFIG was observed, when it supplies the isolated (R-L type) load, Analysis of active power pulsations, reactive power pulsations and DC link voltages fluctuations were done.

Topologies for stand-alone DFIG based wind energy conversion system

A lot of work has been reported on the grid connected operation of DFIG systems. The grid connected generator technology is relatively older and is widely in use today. However, very little attention has been paid toward the issues of stand-alone DFIG systems. The doubly fed induction generator (DFIG) based wind energy generation system can be used as a stand-alone/autonomous power system after the failure of mains in a distributed generation network. This paper gives the modeling of stand-alone generators. This paper provides the brief idea about the basic power electronics converter Topologies and modeling of stand-alone Doubly Fed Induction Generator (DFIG) based Wind Energy Conversion Systems (WECS), which is very helpful for present researcher and students working in this area. Also gives the control techniques of stator voltage and frequency.