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This study introduces an advanced DC-DC power converter with two main objectives, (i) to achieve a wide range of voltage gain, which means the converter may work over a wide range of input voltage for a fixed desired output voltage and (ii) to achieve a reduced input current ripple. Those features are highly desired in renewable energy applications, for example with photovoltaic panels and fuel cells. The proposed converter was designed in a structure in which the input voltage is composed by the difference of two inductor currents, the currents through inductors are driven with transistors that may have different duty cycle, this allows the current ripple cancellation. In addition, the structure of the converter provides a quadratic type voltage gain, which leads to a wide range of operation voltage. The converter achieves both the wire range of voltage gain and current ripple cancellation, nonetheless, the buck-boost capability is also provided. The input current ripple reduction helps preserve the renewable energy sources since they suffer deterioration when current with considerable ripple is drawn from them. Dynamic and steady-state analysis are performed along with the components sizing. Simulation and experimental results are provided to demonstrate the principle of the proposition. 2 voltage gain of the QBC G B voltage gain of the conventional boost converter Q j transistor jth with j = 1, 2 D j diode jth with j = 1, p, n C j capacitor jth with j = 1, p, n, o L j inductor jth with j = 1, 2, o v C j instantaneous voltage of the capacitor C j i L j instantaneous current of the inductor L j

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This paper proposes a fast and reliable two-level islanding detection method (IDM) for grid-connected photovoltaic systems (GCPVSs) based microgrid. In the first level of the proposed IDM, the magnitude of rate of change of output voltage (ROCOV) is computed. If this variable exceeds a predefined threshold, a disturbance is injected into the duty cycle of DC/DC converter after a given time delay to deviate the system operating point away of its maximum power point (MPP) condition. This leads to a substantial active power output and voltage reduction in islanded mode. Therefore, the ROCOV and the rate of change of active power output (ROCOP) indices, measured in the second stage, pose great negative sets at the same time in islanding states. However, the variation of at least one of these variables is nearzero in non-islanding switching events. The assessment of the presented algorithm has been conducted under extensive islanding and non-islanding scenarios for a case study system with two PV power plants using hardware-in-the-loop (HiL) simulation tests. The provided results remark precise islanding classification with eminently small non-detection zone (NDZ) within 510 ms. The presented IDM has the advantages of self-standing thresholds determination, no improper effect on the output power quality, and simple and inexpensive structure. Moreover, the fast MPP restoration of the proposed scheme after islanding identification boosts the chance of seamless reconnection and DG autonomous operation in microgrid. Index Terms-Grid-connected photovoltaic system (GCPVS), Islanding detection method (IDM), Maximum power point (MPP), Microgrid, Non-detection zone (NDZ), Rate of change of active power output (ROCOP), Rate of change of output voltage (ROCOV).

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This study presents a methodology for analysing the transient behaviour of harmonics associated with the interfacing of a synchronous generator and a transmission line. The algorithm is derived entirely in the dynamic harmonic domain that is based on an orthogonal basis and on operational matrices. The main characteristics of the proposed method are: its capability to accurately follow the harmonic content of a transient without the aid of a post-processing tool and its ability to serve as a visually active indicator of the steady-state and transient conditions in a signal. The proposed method is validated by comparing its results against those obtained through a time-domain technique.