Step-up converters are increasingly developed for renewable energy and storage systems in order to raise the output voltage of those resources to higher voltage levels. Conventional step-up structures, such as P-type boost converter, provide low voltage gain, and they must be cascaded with the same modules to produce higher boost factors. This conversion method reduces overall efficiency. Affording higher gains with lower duty cycles and single-stage conversion increase efficiency. This paper proposes a new step-up P-type dc/dc converter with high voltage gain even with lower duty ratios. Additionally, it has continuous input current, high efficiency, and common ground between the input and the output. Detailed analysis is presented, and the performance of this new topology is compared with other high-gain step-up converters. Simulations and experiments evaluate the achievements of this topology. Results prove the proposed structure. INTRODUCTIONStep-up converters are broadly designed and developed for dc microgrid [1, 2], electric vehicles [3, 4], distributed generation [5], and many other applications. There are several methods to design step-up converters [6], which are grouped into six categories, as illustrated in Figure 1. Each method has its pros and cons. The switched-capacitor-based topologies like those presented in [7,8] provide high voltage gain. However, they need large number of capacitors that affect the lifetime of the converter. A similar problem also exists in switched-inductorbased topologies [9]. Transformer-based step-up converters, such as the conventional flyback, forward [10], push-pull, halfbridge, and full-bridge [11] converters, require a large turns-ratio for ultra step-up applications that increases the volume of the high-frequency transformer, and consequently it increases the cost.Recently, a new family of boost converters has been developed, which is called impedance-based converters. These converters usually incorporate an impedance network and a switching circuit, including power switches and power diodes that provide high output voltage gain based on a specificThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Distributed energy resources have been broadly developed in recent years for supporting DC and AC microgrids. Unfortunately, most of them produce low output DC or AC voltages, and interfacing converters are required. These are implemented either in single‐stage or dual‐stage configurations. Step‐up converters are the essential section in dual‐stage designs, which their producing gain is important. Improving the boost factor and efficiency as well as decreasing the number of required components and electrical stresses on power components are the most critical challenges in designing such topologies. Continuing past efforts, this paper proposes a new non‐isolated step‐up DC/DC converter that can be used in low‐voltage distributed power systems and many other applications requiring step‐up DC/DC conversion. The topology requires only one power switch located on the converter's low voltage (LV) side. Hence, it can be easily selected from LV ratings, low on‐resistance power semiconductors. Besides, the converter operates with a continuous input current, which is a valuable feature in connection with current‐sensitive voltage resources. Compared with the recently proposed topologies, the topology provides better conversion gain and efficiency. In this article, the operating principle of the introduced converter is comprehensively investigated. Also, in order to examine the converter performance, experimental results will be presented and analyzed. For this purpose, a 400 V/400 W prototype has been designed and built. Results confirm the above claims and show that the converter efficiency equals 96.1%, and it produces high output voltage gain about 12 times.

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This paper proposes an isolated single‐phase flexible buck‐boost ac–ac converter with an adjustable output frequency and optimized semiconductors count. One power switch only operates with a high switching frequency in each half‐cycle of the input voltage, and others operate with a low switching frequency equal to the output frequency. Thanks to this feature, the converter provides high efficiency, 95.5% in step‐down mode and 91.5% in step‐up mode. The galvanic isolation between the input and output sides is also regarded for the proposed topology by employing two coupled inductors. The converter has an inherent safe commutation by utilizing a simple modulation strategy. Thus, additional snubber circuits and complex commutation strategies are no longer required. The proposed converter does not require any input filter as it operates with the continuous input current. This paper presents the operating principle of the proposed topology in detail. For this purpose, a 200‐W experimental prototype has been designed to examine the performance of the suggested converter for different operating modes and output frequencies. Results confirm the theory and operation of the proposed topology.

Summary In recent years, wind energy has a remarkable growth, and the power systems tend to increase the integration of wind power source. However, the existing power systems are not compatible with the effects resulted by the highly integrated wind power sources. Because of the transmission congestion, available produced wind power is not able to be fed into the grid. This paper presents the application of flexible AC transmission system (FACTS) devices for mitigating the wind power curtailment. A framework of multi period optimal power flow problem (MPOPF) is derived for a wind integrated power system. FACTS devices are utilized in such a way that the total wind curtailment during a specific time horizon is reduced. The proposed MPOPF is tested on modified IEEE 30‐bus load flow test system. It is shown that the amount of curtailed wind power is significantly reduced when FACTS devices are optimally allocated. Copyright © 2016 John Wiley & Sons, Ltd.