Font Size: a A A

Performance Assessment Of The Islanding Detection Method With Voltage And Frequency Dependent Loads

Posted on:2014-07-01Degree:MasterType:Thesis
Country:ChinaCandidate:Q B ZhangFull Text:PDF
GTID:2252330392464284Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
With the rapid development of new energy, distributed generation(DG) and related technology are widely and increasingly applied in practical production. Micro grids improve the security, reliability and economy of power system, while islanding detection should be taken into account. In order to monitor the real-time state of micro-grid and guarantee the stability of system, islanding must be detected quickly and precisely.First, the background, significance and research status of islanding detection are introduced. Then, islanding of DG system is studied comprehensively and systematically. The definition, hazards and principle of island effects are described, anti-islanding test is discussed and the effectiveness of anti-islanding schemes is determined. The theory, advantages, disadvantages and none-detection zone of passive detection method active frequency drift(AFD) and Sandia frequency shift(SFS) are also deeply analyzed.In previous literature, the constant parallel load is usually used as the load model for the study and can’t accurately reflect the performance of the islanding detection. For this reason the comprehensive load model is proposed. Its structure was analyzed, and its power is related to voltage and frequency, being more close to the actual loads. The NDZ of passive detection method with this load model is derived when the inverters supply constant power and constant current. Since the SFS and SMS methods rely primarily on frequency to detect islanding, the load’s frequency dependence may have an impact on its performance. The voltage and frequency influence on the NDZ of them is studied.Finally, a simplified equivalent model of micro grid is built and the interference of these active methods is researched in different multiple DG grid-connected converters: only one inverter with AFD, two inverters with different active detection methods and two inverters with the same method. Simulation is presented to validate the effectiveness of the theoretical analysis.
Keywords/Search Tags:Distributed generation, Islanding, Voltage dependence, Frequency dependence, Passive islanding detection, Active islanding detection, Non-detection Zone
PDF Full Text Request
Related items