This paper presents a new symmetrical single-phase nine-level DC-AC converter for the applications of distributed generation systems (DGS). The proposed multilevel inverter (MLI) utilizes four independent DC sources to generate the nine output voltage levels considering a reduced number of switching devices. The proposed inverter consists of main and auxiliary circuits. The main circuit is a single H-bridge circuit, which is responsible for output voltage polarity. The auxiliary circuit consists of a special combination of switching devices, which are used to synthesize the multilevel output voltage. The merits of the proposed MLI are: increased output voltage levels at reduced number of switching devices, low switching loss, low total harmonic distortion (THD), low dv/dt stress on the switches and hence, low ratings of the switching devices, and low cost. The effectiveness of the proposed MLI and its PWM switching pattern has been verified experimentally by using a laboratory prototype controlled by DSPACE-1103.

To ensure the full benefits from wind generation systems, an effective maximum power point tracking (MPPT) technique should be implemented. In this article, an adaptive fuzzy logic controller (AFLC) is presented as a control methodology for producing the peak power from a permanent magnet synchronous generator (PMSG)-based wind turbine (WT). Regardless of the importance and significance of modeling and simulation processes, experimental studies occupy the most important aspect and remain a big challenge. The first part of this article is devoted to the simulation and modeling of PMSG along with the control system by MATLAB/Simulink® package to develop the control system. To justify the simulation results, experimental validation tests are presented under the same status of wind speed profile and run period. The experimental validation is conducted using the DSPACE DS1104 control board and is compared with simulation results. Moreover, for a realistic response, actual wind speed data is utilized in this research depending on measured data from Ras Ghareb wind farm in the Gulf of Suez, Egypt. The obtained results confirm the superiority of AFLC compared with fuzzy logic controller and conventional PI control schemes. In addition, good tracking with high accuracy is obtained regarding experimental and simulations results. Moreover, an evaluation indices are employed for WT performance based on gross system efficiency and integral of the absolute error (IAE). These indices are used to demonstrate the feasibility of the AFLC methodology compared with traditional approaches under the same wind turbine status.

The high accuracy of fault location in transmission lines reduces outage time and increases system reliability. Most of the time needed for fixing the fault is consumed in determining the location of the fault. Many fault location methods are usable for single-fault events. This paper presents an advanced fault location algorithm to detect, discriminate, and locate single and simultaneous shunt faults. A combination of single-and double-end techniques and traveling wave (TW) fault signature is used to accurately determine the fault location. Comprehensive simulation results are investigated to make sure that the introduced algorithm is capable of detecting and identifying the fault locations accurately whether there is a time shift between occurring the two faults or not. ATP-EMTP package and MATLAB wavelet transform toolbox are used to simulate a 500-kV transmission system and analyze the transient signals generated after the fault occurrence.

This paper presents detailed implementation of static synchronous compensator (STATCOM) based on model predictive control (MPC) for mitigating unbalance in line voltages. The main objective is to evaluate the capability of an enhanced MPC state-space model that can be applied in a general form for any power system. The proposed enhanced MPC state-space model presented in this paper is adapted for mitigating unbalanced voltages at nominated buses by injecting suitable unbalanced currents and reactive powers by STATCOM. In addition, a proposed MPC objective function is developed and implemented to predict STATCOM injected output current according to line voltages of adjacent buses. This enables expecting the fluctuations from any part in the network to maintain nominated bus voltage at reference value. The results of MPC technique are compared with the same MPC technique developed for balanced line voltage mode.

Improving transmission lines (TL) steady-state stability limit can be achieved by Static Synchronous Series Compensators (SSSC) that work as a converter-based compensator. The modification of the SSSC function to inject both active and reactive power into the TL improves its performance according to different indices. The TL improvement indices include the reduction of TL losses, the enhancement of dynamic stability margin and the improvement of voltage profile along the TL. The economic index is considered a vital factor in the design of SSSC devices installed in TLs. This paper proposes an objective function to design and control SSSC devices by considering various technical and economical indices. The formulation of the objective function requires power flow analysis in the compensated transmission line under different loading conditions and compensation levels. The proposed multi-objective function includes the transmission line losses, the dynamic stability span, and the cost of SSSC device. The Genetic Algorithm (GA) and Self-adaptive Multi-population Elitist Jaya Algorithm (SAMPE-JAYA) are proposed as optimization techniques to obtain the minimized value of the multi-objective function. This paper proposes the installation of two SSSC devices in TL that leads to the improvement of the design and control indexes. The proposed objective function and the optimization techniques are applied for tie-line (400kV, 400km) that connects between two networks.