Constrained control of wind turbines for power regulation in full load operation

The cost of electrical power produced by small wind turbines impedes the use of this technology, which can otherwise provide power to millions of homes in rural regions worldwide. To encourage their use, small wind turbines must capture wind energy more effectively while avoiding increased equipment costs. A variable ratio gearbox (VRG) can provide this capability to the simple fixed-speed wind turbine through discrete operating speeds. This is the second of a two-part publication that focuses on the control of a VRG-enabled wind turbine. The first part presented a 100 kW fixed speed, wind turbine model, and a method for manipulating the VRG and mechanical brake to achieve full load operation. In this study, an optimal control algorithm is developed to maximize the power production in light of the limited brake pad life. Recorded wind data are used to develop a customized control design that is specific to a given site. Three decision-making modules interact with the wind turbine model developed in Part 1 to create possible VRG gear ratio (GR) combinations. Dynamic programming is applied to select the optimal combination and establish the operating protocol. The technique is performed on 20 different wind profiles. The results suggest an increase in wind energy production of nearly 10%.

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Stabilizing a 46 MW Multistage Utility Steam Turbine Using Integral Squeeze Film Bearing Support Dampers

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4028715 ◽

2015 ◽

Vol 137 (5) ◽

Cited By ~ 13

Author(s):

Bugra Ertas ◽

Vaclav Cerny ◽

Jongsoo Kim ◽

Vaclav Polreich

Keyword(s):

Steam Turbine ◽

Critical Speed ◽

Stability Margin ◽

Experimental Tests ◽

Turbine Rotor ◽

Squeeze Film ◽

Full Load ◽

Vibration Data ◽

Full Speed ◽

Full Load Operation

A 46 MW 5500 rpm multistage single casing utility steam turbine experienced strong subsynchronous rotordynamic vibration of the first rotor mode; preventing full load operation of the unit. The root cause of the vibration stemmed from steam whirl forces generated at secondary sealing locations in combination with a flexible rotor-bearing system. Several attempts were made to eliminate the subsynchronous vibration by modifying bearing geometry and clearances, which came short of enabling full load operation. The following paper presents experimental tests and analytical results focused on stabilizing a 46 MW 6230 kg utility steam turbine experiencing subsynchronous rotordynamic instability. The paper advances an integral squeeze film damper (ISFD) solution, which was implemented to resolve the subsynchronous vibration and allow full load and full speed operation of the machine. The present work addresses the bearing-damper analysis, rotordynamic analysis, and experimental validation through waterfall plots, and synchronous vibration data of the steam turbine rotor. Analytical and experimental results show that using ISFD improved the stability margin by a factor of 12 eliminating the subsynchronous instability and significantly reducing critical speed amplification factors. Additionally, by using ISFD the analysis showed significant reduction in interstage clearance closures during critical speed transitions in comparison to the hard mounted tilting pad bearing configuration.

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Stabilizing a 46 MW Multi-Stage Utility Steam Turbine Using Integral Squeeze Film Bearing Support Dampers

Volume 7A: Structures and Dynamics ◽

10.1115/gt2014-27066 ◽

2014 ◽

Author(s):

Bugra Ertas ◽

Vaclav Cerny ◽

Jongsoo Kim ◽

Vaclav Polreich

Keyword(s):

Steam Turbine ◽

Critical Speed ◽

Stability Margin ◽

Experimental Tests ◽

Turbine Rotor ◽

Squeeze Film ◽

Full Load ◽

Vibration Data ◽

Multi Stage ◽

Full Load Operation

A 46 MW 5,500 rpm multistage single casing utility steam turbine experienced strong subsynchronous rotordynamic vibration of the first rotor mode; preventing full load operation of the unit. The root cause of the vibration stemmed from steam whirl forces generated at secondary sealing locations in combination with flexible rotor-bearing system. Several attempts were made to eliminate the subsynchronous vibration by modifying bearing geometry and clearances, which came short of enabling full load operation. The following paper presents experimental tests and analytical results focused on stabilizing a 46 MW 6,230kg utility steam turbine experiencing subsynchronous rotordynamic instability. The paper advances an integral squeeze film damper (ISFD) solution, which was implemented to resolve the subsynchronous vibration and allow full load and full speed operation of the machine. The present work addresses the bearing-damper analysis, rotordynamic analysis, and experimental validation through waterfall plots, and synchronous vibration data of the steam turbine rotor. Analytical and experimental results show that using ISFD improved the stability margin by a factor of 12 eliminating the subsynchronous instability and significantly reducing critical speed amplification factors. Additionally, by using ISFD the analysis showed significant reduction in interstage clearance closures during critical speed transitions in comparison to the hard mounted tilting pad bearing configuration.

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Performance Analysis of a Producer Gas-fuelled Heavy-duty SI Engine at Full-load Operation

Energy Procedia ◽

10.1016/j.egypro.2015.12.007 ◽

2015 ◽

Vol 82 ◽

pp. 149-155 ◽

Cited By ~ 11

Author(s):

Paolo Gobbato ◽

Massimo Masi ◽

Marianna Benetti

Keyword(s):

Performance Analysis ◽

Producer Gas ◽

Heavy Duty ◽

Si Engine ◽

Full Load ◽

Full Load Operation

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Full-Load Converter Connected Asynchronous Generators for MW Class Wind Turbines

Wind Engineering ◽

10.1260/030952405774857833 ◽

2005 ◽

Vol 29 (4) ◽

pp. 341-351 ◽

Cited By ~ 7

Author(s):

Vladislav Akhmatov

Keyword(s):

Wind Turbines ◽

Short Circuit ◽

Wind Farms ◽

Variable Speed ◽

Full Load ◽

Frequency Converters ◽

Fault Ride Through ◽

System Operator ◽

And Control ◽

Large Wind

Wind turbines equipped with full-load converter-connected asynchronous generators are a known concept. These have rating up to hundreds of kW and are a feasible concept for MW class wind turbines and may have advantages when compared to conventional wind turbines with directly connected generators.* The concept requires the use of full-scale frequency converters, but the mechanical gearbox is smaller than in conventional wind turbines of the same rating. Application of smaller gearbox may reduce the no-load losses in the wind turbines, which is why such wind turbines with converter connected generators may start operation at a smaller wind speed. Wind turbines equipped with such converted connected asynchronous generators are pitch-controlled and variable-speed. This allows better performance and control. The converter control may be applied to support the grid voltage at short-circuit faults and to improve the fault-ride-through capability of the wind turbines, which makes the concepts relevant for large wind farms. The Danish transmission system operator Energinet-DK has implemented the general model of wind turbines equipped with converter connected asynchronous generators with the simulation tool Powerfactory (DlgSilent). The article presents Energinet-DK's experience of modeling this feasible wind turbine concept.

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