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URN etd-0626118-122038
Author Mkhonzeni Mazambane Dlamini
Author's Email Address mkhonze@gmail.com
Statistics This thesis had been viewed 5350 times. Download 98 times.
Department Electrical Engineering
Year 2017
Semester 2
Degree Master
Type of Document
Language English
Title The Effects of Dynamic Load on the LVRT Performance for DFIG Wind Farms and Optimal Sizing and Location of STATCOM for LVRT Enhancement
Date of Defense 2018-07-23
Page Count 120
Keyword
  • AIAE
  • PCC
  • LVRT grid code
  • Dynamic loads
  • Disconnection
  • DFIG wind turbine
  • STATCOM
  • Abstract Wind power is the fastest growing renewable energy source in the world. The global quest for a cleaner environment, improvement in wind turbine technology and government pledges to support renewable energy generation has resulted in significantly high renewable energy penetration in power systems. The high penetration coupled with its intermittency, fluctuation and non dispatchability of renewable power has resulted in shortage of power reserves and system inertia as conventional machines are shrinking in the system.
    Grid codes specially formulated for renewable energy sources have been enacted by power system operators (PSO) to give grid connection, steady state and dynamic operational guidelines. In this study, the low voltage ride through (LVRT) grid code for wind turbines is considered. The LVRT requirement stipulates that if voltage recovery to 90% of nominal voltage following a fault is slower than the set-times at different sag levels, wind farm could disconnect from the grid. Disconnection of wind power in a heavily constrained system can be catastrophic and need to be avoided as the system has less power reserves.
    Voltage recovery is greatly affected by dynamic loads. Power systems loads are estimated to be roughly 60% dynamic loads which are mostly induction motors. In this study, a PSS/E CLOD composite load model with motor sub-models are used. Undesired disconnection of wind farms (WF) could be mitigated through LVRT enhancement by static synchronous compensator (STATCOM) device at strategic locations. The optimal STATCOM capacity depends on the actual or anticipated dynamic load proportion in the system and the required voltage recovery time.
    STATCOM locations are determined through the use of Average Integral Absolute Error (AIAE) of voltage deviation as indices and the capacity is determined to comply with German LVRT grid code voltage recovery requirement. In the study it is shown that dynamic var planning can improve wind turbine uptime, overall system integrity and that a single strategically located dynamic var source could serve several adjacent WFs to reduce costs of LVRT enhancement.
    Advisory Committee
  • Dr. Kin-Cheong Sou - chair
  • Dr. Chun-Lien Su - co-chair
  • Dr. Jen-Hao Teng - co-chair
  • Dr. Chan-Nan Lu - advisor
  • Files
  • etd-0626118-122038.pdf
  • indicate access worldwide
    Date of Submission 2018-07-27

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