ISLANDING DETECTION AND POWER QUALITY ANALYSIS IN MICROGRID a Dissertation Submitted to the GRADUATE SCHOOL OF ENGINEERING AND SCIENCE OF SHIBAURA INSTITUTE OF TECHNOLOGY by TRAN THANH SON

 ISLANDING DETECTION AND POWER QUALITY ANALYSIS IN MICROGRID 

a Dissertation Submitted to the GRADUATE SCHOOL OF ENGINEERING AND SCIENCE OF SHIBAURA INSTITUTE OF TECHNOLOGY 

by TRAN THANH SON 

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY SEPTEMBER 2019

Abstract

The microgrid (MG) has been developed based on the important con- cept of distributed generation (DG) with high penetration of renew- able energy integrated with energy storage systems (ESSs). MGs can operate in both grid-connected and islanding mode. Therefore, this thesis focuses on autonomous multi-islanded entities and the seamless reconnection to the main grid as the self-healing ability of the fu- ture power system. The minimization of power quality issues (mainly that of voltage, frequency, and harmonics) in such entities based on controllers, with or without intercommunication, is also an important part of this thesis. The future power system, with the signicant pen- etration of distributed generations (DGs), can rapidly respond to any problem occurring within it by separating into autonomous islanded entities to prevent the disconnection of DGs. As a result, high-quality and continuous power is supplied to consumers. The future research that is necessary for the realization of the future power system is discussed.

Besides, the emergence of Distributed Generation (DG) in the elec- tric system has brought about the appearance of the islanding phe- nomenon. In AC networks, there are a lot of Islanding Detection Methods (IDMs) have been studied. However, not too much IDMs in DC networks have been published because of the absence of frequency and reactive power. The active IDM based on injected perturbation signal and rate of change of power output is proposed. This IDM can detect islanding condition not only in the worst case (the power of the load and PV are equal) but also in another case (the power of load is greater than the power of PV). It can be applied to both single

and multi-PV operation scenarios. Also, the cancellation problem is analyzed and the solution is proposed to solve this problem. Besides, the eectiveness of the proposed method, the cancellation problem, and the solution are verified by simulation in Matlab/Simulink.

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