| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系 === 107 === Unbalanced loads and low power factor are the most commonly encountered power quality issues in power distribution systems. In addition to increasing the loss of the line, they also affect normal operation of transformers and motors. In order to improve problems mentioned above, a -connected Static Var Compensator is set up and is calculated based on a new theoretical method of power analysis. The PID controller is used to control its firing angles so that it can balance the unsymmetrical load as well as correct the power factor at the delivery point. The theoretical method does not require information on the type and the connection method of the load. It can be processed merely by identifying both active and reactive power consumption. Therefore, any load connected to a three-phase three-wire (or four-wire) system or a single-phase load can be converted into a balanced load with unity power factor. Finally, simulation is performed by ATP-EMTP software to evaluate the system performance. Results show that the design is able to reach either one or both goals, namely correcting power factor and balancing loads. Consequently, it can reduce the power loss, cut down the current unbalance rate, improve the power quality without the need of active power filter, and lower the cost.
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