Methods to Enable Open-Loop Synchronization For Islanded Systems

  • Author / Creator
    Zhou, Yaxiang
  • Interconnection of two power systems is a common task. An example is to reconnect an islanded system to the main power grid. Synchronization condition must be satisfied when interconnecting these two systems. Traditionally, feedback-control based methods are used to adjust the generating units of the islanded system to meet the synchronization criteria until satisfied. Implementing such methods can be difficult when multiple generating units need to be adjusted. Moreover, islanded systems might be located in remote areas where infrastructure for feedback loop is not readily available and costly to build. This thesis proposes a novel method to enable open-loop synchronization of an islanded system to the main grid. The idea is to pre-insert an impedance to reduce the synchronization transients and then bypass it after the initial transients are over. With this method, infrastructure cost and complexity of synchronization can be reduced significantly since the communication links between the breaker and the generators are no longer required. In addition, the extra efforts required for generator adjustments can be avoided. Technical considerations and design method for the selection of pre-insertion impedance size is presented. A simulation study is conducted to evaluate the performance of the method. The results prove that the transient levels can be effectively reduced and open-loop synchronization is indeed achievable. The thyristor based synchronizer to enable open-loop synchronization is also found to be feasible.

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  • Graduation date
  • Type of Item
  • Degree
    Master of Science
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    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.