Essam El-Din Mohamed Aboul Zahab

The prevalence rate of photovoltaics (PV)-based generation systems has increased by more than 15 folds in the last decade, putting it on the top compared to any other power generation system from the expandability point of view. A portion of this huge expansion serves to energize standalone remote areas. Seeking improvements from different aspects of PV systems has been the focus of many studies. In the track of these improvements, parallel MPPT configuration for PV standalone systems have been introduced in the literature as an alternative to a series configuration to improve the overall efficiency of standalone PV systems.
However, this efficiency improvement of the parallel MPPT configuration over the series one is not valid for
any standalone application, therefore an assessment procedure is required to determine the most efficient MPPT configuration for different standalone applications. Therefore, in this study, an assessment procedure of parallel MPPT is conducted to demonstrate the suitability of utilizing such a configuration compared to series one, based on load daytime energy contributions. This assessment will help PV system designers to determine which MPPT configuration should be selected for applications under study. Furthermore, a new utilization of parallel MPPT configuration is introduced for operating universal input power supply (UIPS) loads to eliminate the inverter stage, thereby increasing the overall system efficiency and reliability. Finally, a systematic procedure to size the complete system is introduced and reinforced by a sizing example.

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This paper proposes an adaptive dynamic Mho distance relay based on a phase comparator scheme for protecting interconnected transmission networks compensated with a Thyristor Controlled Series Capacitor (TCSC). The proposed relay uses an impedance index factor to initiate the fault detection subroutine. The RMS of the positive sequence current of the faulted loop and the TCSC terminal current are compared for TCSC zone identification. A phase comparator for ground and phase distance elements is proposed, relying on the positive sequence voltage as a polarized memory quantity, while the operating and polarizing quantities are developed using estimated TCSC impedance to mitigate its negative impact. The proposed scheme is easy in implementation and independent on synchronized data transfer, as minimum communication requirements are needed. To evaluate the performance of the proposed scheme, extensive simulation studies were carried out on an IEEE9 bus system compensated with TCSC for different firing angles covering four modes of TCSC operations, different fault types, and fault locations. In addition, an IEEE-39 bus network, as a large interconnected system, is tested for validation purposes. The achieved results designate the precision of the proposed scheme. Moreover, the results indicate its effectiveness for fault resistance tolerance, close-in three phase faults, and stable power swing phenomenon compared with conventional relays.