One of the most widely used techniques for controlling the dc microgrid is the droop control method. The associated problems of the droop based systems such as the current sharing errors and the voltage deviation are solved using current sharing loops and secondary control loop, respectively. This paper presents an adaptive droop scheme for dc microgrids to overcome the non-linearity of the system. The droop resistance is adjusted using the adaptive PI controller to eliminate the current sharing error of each unit in the microgrid. In addition, another adaptive PI controller is dedicated for the secondary loop to regulate the dc bus voltage of the microgrid by shifting the droop lines. In the proposed scheme, only the current and voltage at the dc bus of the microgrid need to transmit through low-bandwidth communication channels to individual units. Moreover, the Sliding Mode Control (SMC), which is distinguished by robustness and fast dynamic response, is utilized to manipulate the output voltage and the input current of each converter, instantaneously. The dynamic performance of the proposed adaptive droop scheme is evaluated using the PSCAD/EMTDC simulation package.

This paper introduces a hybrid maximum power point tracking (MPPT) technique for photovoltaic (PV) arrays working under partial shading conditions. This new algorithm can combine a traditional MPPT algorithm, such as perturb and observe, or incremental conductance, with the artificial neural network (ANN) technique. The proposed hybrid MPPT algorithm is based on the ANN and used to predict the global MPP region by estimating its voltage boundaries. Consequently, the conventional MPPT algorithm searches for the MPP in the predicted region. The proposed technique is modeled and simulated using MATLAB/Simulink. The results show the effectiveness of the proposed hybrid MPPT technique to track the global MPP accurately with a rapid response comparing to the ANN; this increases the output power level of the PV array under various shading patterns.

Distributed Generation (DG) exists in distribution systems and is installed by either the utility or the customers. This paper proposes a novel utilization of the existing DG nonlinear interface not only to control the active power flow, but also to mitigate unbalance and harmonics, and to manage the reactive power of the system. The proposed Flexible Distributed Generation (FDG) is similar in functionality to FACTS, but works at the distribution level. Moreover, a novel ADAptive LINEar neuron (ADALINE) structure is presented. The new structure is applied to multi output (MO) systems for parameter tracking/estimation, and is called MO-ADALINE. It is dedicated to symmetrical components estimation. The control loop combines a Fuzzy Logic Controller (FLC) for voltage regulation, and a processing unit-based ADALINE to deal with unbalance, harmonics and reactive power compensation. One advantage of the proposed control system is its insensitivity to parameter variation, a necessity for distribution system applications. Simulations of the suggested FDG based control algorithm are conducted to evaluate the performance of the novel system.

In this paper, a soft switching interleaved boost converter (SS-IBC) using auxiliary resonant circuit for electric vehicles (EV) applications is proposed. Several phases of the proposed converter can be connected to make a multiphase interleaved boost converter. The operation of multiphase interleaved boost converter is identical to that of the one phase boost converter. All phases are ideally identical with shifted control signals and are controlled by PWM control strategy of equal switching frequency and duty cycle. The proposed converter can be considered as a cost effective retrofit to the grid integrated battery charging applications. It affords a steady electrical power for the load not only from the utility or classical energy storage systems as batteries, but also from renewable energy systems like photovoltaic (PV), wind or fuel cell systems. An appropriate design example demonstrates the size of the design circuit components and parameters are investigated. Analysis, design, and simulation of the presented converter are verified using PSIM simulation software on an 8.2 kW setup system with a conversion efficiency more than 97% over a wide output power conversion range from rated power to a minimum power of 460 W with complete soft switching operation. The converter performance is also validated experimentally on a downsized hardware rated 1.0 kW and the maximum efficiency is found to be 98.78%.

This paper introduces an interleaved buck-boost converter with reduced power electronics devices count in comparison with the conventional topology. The proposed converter consists of a single buck converter followed by $n$ parallel interleaved boost converters. The buck switch is gated only if any of the boost switches is gated. In addition to the reduced switches count, the proposed converter offers the following advantages, soft start-up and shutdown capabilities. In addition, the buck stage gives the ability to protect the power electronic devices and to isolate the supply during load failure or overload. Moreover, the proposed converter performs as an interleaved boost converter for high voltage gain requirements with the same switching scheme. Furthermore, it offers fast dynamic performance with smooth transition from the buck mode to the boost mode. This paper investigates the eight different operating zones of the proposed three-phase interleaved buck-boost converter for non-overlapping gate signals operation. The detailed analysis and zones of operation are presented and experimentally validated. In addition, a simple control system is presented to operate the proposed converter as dc-dc converter or ac-dc converter. More study cases are carried out to evaluate the different capabilities of the proposed converter.

Modular Multilevel Converter (MMC) will be extensively used in High-Voltage Direct Current (HVDC) transmission networks because of its superior characteristics over Line Commutated Converter (LCC). Increasing the reliability of the MMC is directly related to the balancing of the MMC sub-module capacitors voltages which guarantees the proper operation of the converter and lowers the stress on the sub-modules. This paper presents an adaptive voltage balancing strategy based on capacitor voltage estimation utilizing a hybrid ADALINE-RLS scheme. The proposed strategy eliminates the need of measuring sub-modules capacitor voltages and associated communication link with the central controller. Furthermore, the estimated capacitor voltages are utilized to detect and localize different types of sub-module faults. After isolating the faulty sub-modules, the proposed fault tolerant control unit (FTCU) modifies the parameters of the voltage balancing strategy to overcome the reduction of the active submodules. The dynamic performance of the proposed strategy is investigated, using PSCAD/EMTDC simulations and hardware in the loop (HIL) real-time simulations, under different normal and faulty operating conditions. The accuracy and the time response of the proposed fault detection and tolerant control units result in stabilizing the operation of the MMC under different types of faults. Consequently, the proposed integrated control strategy improves the reliability of the MMC.