Development Of Variable Speed Wind Turbine Test Bench For PMSG With Maximum Power Point Tracking

The unavailability of wind resources in the laboratory has led to the research and development of an accurate test bench for the Wind Energy Conversion System (WECS). Prototype for a wind turbine is essential to replicate the characteristics of the system for variable wind speeds without depending o

Project Title

Development Of Variable Speed Wind Turbine Test Bench For PMSG With Maximum Power Point Tracking

Project Area of Specialization

Electrical/Electronic Engineering

Project Summary

The unavailability of wind resources in the laboratory has led to the research and development of an accurate test bench for the Wind Energy Conversion System (WECS). Prototype for a wind turbine is essential to replicate the characteristics of the system for variable wind speeds without depending on the natural wind in the vicinity. Maximum power point tracking (MPPT) algorithms are embedded into the system to increase efficiency by reaching optimal speeds. The development of WECS is necessary for the need of detailed designing in laboratories for understanding and learning wind energy. To understand the above mentioned, it is required to determine the best configuration and maximum power point tracking method, all of which require numerous on-site experiments and surveys. Hence an accurate Wind Turbine Test Bench System (WTTBS) would validate the concept and prototype in laboratories for the development of the Wind Energy Conversion System (WECS). The test bench should be able to reproduce the characteristics of the actual wind turbine which includes variation in wind speeds. The system would work on any given wind speed and be able to produce a wind profile which would further be used for maximum power point tracking. A wind emulator includes a converter and induction motor (IM) to produce mechanical power and converted it to electrical power through a permanent magnet synchronous generator (PMSG). The proposed WTTBS is developed to emulate Permanent Magnet Synchronous Generator (PMSG) because of its high efficiency, gearless construction, and power density. 

Project Objectives

The best places for wind farms to be set up are near coastal areas, at the tops of rounded hills, open plains, and gaps in mountains – places where the wind is strong and reliable. An average of 25km/h wind is required to produce sufficient electricity. The institute doesn’t have continuous wind speeds up to this value and cannot be practically implemented in laboratories as compared to solar energy.

WTTS is developed to get more accurate knowledge of wind speed characteristics and variations involved in real-time scenarios. The system will be able to achieve efficiency and could be further enhanced in the future by other students. It will lay down the milestone for the institute to excel further in wind energy.

To develop variable speed drive which would be able to efficiently vary the speed and torque of the induction motor to produce different wind speeds. 3 phase inverter would be built for producing AC with the help of the SVPWM switching technique. Field-oriented control would be implemented on the system for controlling purposes.

Optimal speed reference is developed and embedded into the WTTBS as feedback which is used in Maximum Power Point Tracking (MPPT). It would distinguish the regions where the wind turbine emulator efficiently converts mechanical energy into electrical energy. Power and speed graphs would be generated to trace the pattern for different wind profiles.

Project Implementation Method

The system will utilize an Induction motor to emulate different speeds of wind. The speed of the induction motor will be varied by changing the stator current by a FOC method. There will be an incremental rotary encoder attached to the PMSG to measure speed which will be used to apply the Hill Climb Search Control for MPPT. 

A DC source is connected to a 6 level 3 Phase DC/AC inverter circuit as shown in fig2. The gate of the IGBT is used for switching which produces a 3 phase AC output. To produce a sinusoidal wave for AC with 120 phase shifts we will use SVPWM to set the switching timing for the gates of the IGBT’s.

Space vector pulse width modulation is an algorithm for the control of PWM in the final stage of field-oriented control (FOC). It is used for determining the pulse-width modulated signal for the inverter switches to generate the desired 3 phase voltage to the motor. 

There are only six different voltage angles available with no middle ground. To rotate the motor smoothly there is a dire need to rotate a voltage vector throughout 360°.  Therefore, since all the available voltages can be used, SVM does not present the voltage limitation of SPWM.To implement space vector modulation, a reference signal Vref is sampled with a frequency fs (Ts = 1/fs). The reference signal may be generated from three separate phase references using the transform. The reference vector is then synthesized using a combination of the two adjacent active switching vectors and one or both of the zero vectors. Various strategies of selecting the order of the vectors and which zero vectors to use exist. Strategy selection will affect the harmonic content and the switching losses.

Field-oriented control (FOC) was developed in the early 1970s and made it feasible to control the induction motor as a separately excited DC motor. Field-oriented control can be classified as indirect field-oriented (IFO) and direct field-oriented (DFO) control. Both approaches provide torque control of the induction motor by decoupling the torque and flux.

There are different ways of implementing the vector control strategy according to the choice of the reference frames for the space vectors. In an induction motor, there are three distinct flux space phasors: air gap flux, stator flux, and rotor flux.   It will be used to set the switching time of the IGBT by varying the frequency of the SVPWM. By changing the switching time, the stator current of the induction motor can be changed accordingly to achieve the desired speed. 

For Maximum PowerPoint Tracking (MPPT), a hill climb search algorithm will be used that will first measure the rotor speed (?) and mechanical power (P) of the PMSG and then will compare those with the power and rotor speed. 

         

Benefits of the Project

An efficient drive will be developed which could replicate the characteristics of a wind turbine. The energy capture potential in the wind changes with a change in the wind speed. Hence a wind turbine with variable speed capability will harness more power than its fixed speed counterpart. With the use of power electronics converters, it is possible to operate the wind turbines at variable speed. The proposed controller further increases the efficiency of the variable speed wind turbine by tracking the Maximum PowerPoint (MPPT). Wind profiles will be developed according to our structured data and Maximum power point tracking will make the PMSG efficient. 

Technical Details of Final Deliverable

The test bench will emulate the wind profiles for wind speeds in the range of 2 to 12 m/s. The output of rotor speed would be varied efficiently with minimum settling time and less overshoot with the help of PI controllers. The output graph of mechanical power versus wind speed will be plotted and our PMSG must be operating at the highest point of the wind profile graph. 

Final Deliverable of the Project

HW/SW integrated system

Core Industry

Energy

Other Industries

Core Technology

Others

Other Technologies

Clean Tech

Sustainable Development Goals

Climate Action

Required Resources

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