الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The hybrid MG architecture is getting popular because it combines the advantages of both AC and DC systems. It is capable of providing dependable and cost-effective solutions that can mitigate the need for multistage AC-DC conversions. Despite the several advantages of AC/DC hybrid MGs, developing a protection scheme is one of the most complex challenges facing MG technology. Several technical studies have been conducted to develop protection schemes for DC MG and even more for AC MG. However, there are few studies on the operation of the hybrid AC/DC system, particularly on developing a reliable protection scheme.
The conventional distribution networks operate radially, with power flowing in a single direction from huge power plants to consumers. In such systems, the protection is performed by overcurrent-based relays, and the coordination is performed by a time-grading algorithm between upstream and downstream devices. However, the use of the traditional overcurrent-based protective scheme is no longer appropriate for both AC and DC MGs integrated in hybrid distribution network so that alternative solutions must be developed. Several protection algorithms, besides current-based ones, are proposed in several studies. However, most of these schemes face several issues.
This thesis proposes a protection scheme based on wavelet analysis for a hybrid AC/DC network. Compared to existing wavelet-based methods, this scheme takes into consideration both the AC and DC side protection and the majority of the disturbances that affect the network. Additionally, because it is based on local measurements, the proposed scheme does not require communication infrastructure. Furthermore, the scheme offers a fast-acting fault detection capability. The scheme works under different operating conditions and can discriminate between non-fault disturbances and fault conditions whether symmetrical or unsymmetrical faults.
In addition, this thesis proposes a protection coordination technique between the AC and DC sides in the hybrid distribution network. The proposed technique is based on using a relay in front of the voltage source converter (VSC) linking both the AC and DC sides. This relay uses a combination of wavelet analysis, of the current and voltage signals at the relay point, and features extraction techniques for the coordination process. Moreover, the classification of faults for AC-side faults is achieved by the proposed technique.
The modelling and simulation of the adopted hybrid AC/DC distribution network are accomplished using MATLAB/Simulink® software package. The reliability of the proposed scheme is tested under different operating conditions such as islanding, different loading, and different irradiation. The results show that the proposed scheme offers fast-acting detection for both primary and backup protection with a reliable coordination algorithm.