The Future
Pioneers
speed , the excess wind energy can be stored in the accumulator . This excess wind energy is released to the system when the wind speed is below the rated speed .
Power Regenerative HST wind turbine research platform : To demonstrate and validate the performance of the HST , we have successfully designed , constructed and commissioned a unique power regenerative test platform at University of Minnesota ( UMN ).
Figure3 . Schematic of the testbed .
This testbed is one of a kind in the world . The testbed can simulate rotor torque generated from real wind profiles . It is a regenerative system consuming less power to operate . The testbed is instrumented with multiple sensors to accommodate and test a variety of hydraulic fluids , components and controls . It consists of two closed loop hydrostatic circuitsas shown in Figure 3 . The block in dark gray is the HST under investigation . The other block is the hydrostatic drive ( HSD ), which is used to simulate the rotor driven by time varying wind . Instead of dissipating the turbine output power , the power is fed back to the HSD . A variable frequency driven electric motor is mounted
Figure4 . PowerRegenerative HST windturbine research platform at UMN
on the turbine output shaft to make upfor the losses of the HST and HSD . Because of power regeneration , the research platform is capable of generating 105 kW output with only 55 kW of electrical input .
The power regenerative testbed is shown in Figure 4 . It has pressure , temperature and flow sensor modules in the hydraulic line and torque sensors and speed encoders in the mechanical line . The testbed is equipped with 27 sensors to monitor the system performance and three analog inputs to control the testbed . It is incorporated with heat exchangers to maintain the temperature of hydraulic fluids . It is designed to operate at maximum pressure of 5000 PSI . It has safety valves to protect the hydrostatic circuit [ 5,6 ].
Significance of research :
This research will increase understanding of the HST for wind turbine applications . This will accelerate the development of wind power by increasing reliability , decreasing installation cost up to 12 %, reducing maintenance costs and improving the efficiency of distributed wind power generation . The main applications of distributed wind are residences , farms , small industries and institutions . With affordable prices , the distributed wind market will grow and contribute to our wind generation goal . This will also reduce millions of tons of CO2 emission and provide a cleaner environment for our next generation . The outcomes of the project will stimulate industry to develop more efficient hydraulic components , system and control for wind applications and contribute to our green economy .
Biswaranjan Mohanty PhD Candidate Department of Mechanical Engineering University of Minnesota , Minneapolis , MN 55455
References :
1 . Wind vision report by Department of Energy , https :// energy . gov / eere / wind / wind-vision .
2 . Distributed wind market report by Department of Energy , https :// energy . gov / eere / wind / downloads / 2015- distributed-wind-marketreport .
3 . Sheng , S ., Report on wind turbine subsystem reliability- a survey of various databases . National Renewable Energy Laboratory , Golden , CO , Tech . Rep . NREL / PR-5000-59111 , 2013 .
4 . Thul , B ., Dutta , R ., Stelson , K . A ., Hydrostatic transmission for mid-sized wind turbines , 52nd National Conference on Fluid Power , Las Vegas , USA , 2011 .
5 . Mohanty , B ., Wang , F ., and Stelson , K . A ., “ Design of power regenerative hydrostatic wind turbine test platform ,” Proceedings of the 10th JFPS International Symposium on Fluid Power Fukuoka , Japan , Oct 2017 .
6 . Mohanty , B ., and Stelson , K . A ., “ Characterization and calibration of a power regenerative hydrostatic wind turbine test bed using an Advanced Control Valve ,” Proceedings of the 11th International Fluid Power Conference , Aachen , Germany , March 2018 .
august-september 2018 | Global MDA Journal | 45