Integrated efficient islanding detection method for synchronous-typed distributed generation
The modern electrical grid constitutes an increase in Distributed Generation (DG) application in order to fulfil the demand of electricity. These DG infiltrations altered the classical grid architecture hence affecting the grid protection structure specifically related to the islanding situation. Un...
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| 要約: | The modern electrical grid constitutes an increase in Distributed Generation (DG) application in order to fulfil the demand of electricity. These DG infiltrations altered the classical grid architecture hence affecting the grid protection structure specifically related to the islanding situation. Unintentional islanding brings serious threat to the maintenance worker in charge of the islanded grid, electrical instruments as well as the DG connected in the microgrid. Malaysian main utility provider that is Tenaga Nasional Berhad (TNB) still applies the Rate of Change of Frequency (ROCOF) relay that experienced inefficiency as the DG penetration escalates. Therefore, the motivation of this thesis is to enhance the protection relay without substantially altering the grid, particularly for synchronous typed DG (SG). Passive islanding detection (PID) method that is the Rate of Change of Positive Voltage (ROCOPV) is adopted to be integrated with the classical ROCOF method. Several objectives are derived based on the motivation which are to conduct analysis on the ROCOF, to apply the ROCOPV for the ROCOF enhancement, and to conduct analysis on the enhanced method. The approaches in this thesis are implemented paralleled to the stated objectives. Initially, the ROCOF analysis is performed to reaffirm the ROCOF inefficiency in which involves cases of islanding as well as non-islanding. In order to collate the existing ROCOF method and the proposed ROCOPV, this analysis is further applied to the ROCOPV. Therefore, in addition to the verification of the ROCOF inefficiency, the ROCOPV capability is appraised as well. Based on the data attained, the ROCOF and ROCOPV are integrated and hence evaluated by applying similar islanding and nonislanding cases but implementing a different grid that is modelled based on the Green City area in Malacca. Originally, the Green City area consists of a solar station in which is excluded in the modelled grid, however a SG is rather included to demonstrate the DG as well as fulfilling the thesis limitation. The analysis findings substantiated that the efficiency of the classical ROCOF is declining as the grid intricacy expand. On the other hand, the ROCOPV is demonstrated to be adequate to fill in the ROCOF efficiency gap hence, these methods are integrated to attend to the islanding detection issues. The integrated ROCOF and ROCOPV is able to rapidly detect as well as differentiate the islanding and non-islanding affairs without any non-detection zone (NDZ). All the islanding cases are identified therefore the SG connection to the grid is interrupted, in less than 2 seconds, fulfilling the IEEE 1547 international standards for islanding detection period. |
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