考虑电网内阻影响的孤岛检测研究

发布时间：2018-08-07 19:57

【摘要】：在基于电流幅值扰动的孤岛检测过程中,电网未断电时,由于电网内阻的存在,公共耦合点(PCC)电压会随着电流扰动而波动,可能造成检测误判。为此,本文采用间歇性正反向电流幅值扰动,利用逆变输出电流和PCC电压的相关系数判断孤岛,并研究电网内阻对孤岛检测的影响。通过对符合IEEE Std 929—2000标准孤岛检测电路模型的理论分析,分别得到了在电网断电孤岛运行和电网未断电且考虑电网内阻时,PCC电压与扰动电流之间的关系,同时得到了两种状态下相关系数计算值及其与电网内阻的关系,为相关系数保护阈值的选取提供了理论依据。实验结果显示,方法可在规定时间内检测出孤岛,验证了理论分析的正确性。本文提出的孤岛检测方法克服了电网内阻致使PCC电压波动的影响,检测结果不依赖于电压额定值,且在PCC电压不超出过欠压保护范围时即可检测出孤岛,检测可靠性高。
[Abstract]:In the process of islanding detection based on current amplitude disturbance, the common coupling point (PCC) voltage will fluctuate with the current disturbance due to the existence of the network internal resistance when the power grid is not power off, which may cause the detection error. For this reason, the intermittent forward and backward current amplitude disturbance is used to judge the isolated island by using the correlation coefficient of the inverter output current and the PCC voltage, and the influence of the internal resistance of the power network on the detection of the isolated island is studied. Based on the theoretical analysis of the islanding detection circuit model which conforms to the standard of IEEE Std 929-2000, the relationship between the voltage and the disturbance current is obtained when the isolated island is running and the power network is not off and considering the internal resistance of the power network. At the same time, the calculated value of correlation coefficient and its relation with the internal resistance of power network under two states are obtained, which provides a theoretical basis for the selection of the threshold value of correlation coefficient protection. The experimental results show that the method can detect the isolated islands within a specified time and verify the correctness of the theoretical analysis. The islanding detection method proposed in this paper overcomes the influence of the PCC voltage fluctuation caused by the internal resistance of the power network. The detection results do not depend on the voltage rating, and the isolated islands can be detected when the PCC voltage does not exceed the range of under-voltage protection, and the detection reliability is high.
【作者单位】：北京航空航天大学自动化科学与电气工程学院;
【分类号】：TM615

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