In recent decades, because of some main and principle world problems such as increasing the population, global warming, climate changes, and fossil fuel sources reduction, the using of renewable energies has impressively increased that can solve and reduce the caused problems by traditional POWER plants, and also can control POWER system the important indexes such as LOSSES, voltage drop, transferring capacity. Reactive POWER has an important role in controlling and minimizing of LOSSES, the optimal distribution of reactive POWER in presence of Distributed generation (DG) units in distribution networks is an important and key problem. In this paper, for uncertainties modelling of DG units and optimizing the reactive POWER, the statistical-quality based Taguchi method and Genetic algorithm are used, respectively.  The simulation of this paper is checked and done in MATLAB and MINITAB using IEEE 57-bus standard network, and simulation results show 5.5 MW reduction of the distribution network LOSSES.

The inverter is one of the main components of photovoltaic POWER plants. Since the POWER output of the POWER plant is directly related to the inverter's performance, the inverter LOSSES have an important effect on the generation and efficiency of the photovoltaic plant. The most important of inverter LOSSES are the inverter clipping and inverter efficiency LOSSES. Some factors affecting clipping LOSSES and inverter efficiency are the sea surface height, ambient temperature, input POWER DC, wind speed, air density, radiation, and so on. Due to the high radiation potential, the wide area, and the variety of climate in Kerman province, in this article, Kerman province has been selected for the installation of photovoltaic POWER plants and the effects of environmental factors on inverter clipping LOSSES and inverter efficiency are studied in different areas of Kerman. In simulating the effects of several factors such as wind speed, radiation, altitude, ambient temperature, wiring LOSSES, inverter POWER consumption during operation and at the night, shadow and dust LOSSES are considered. In addition, the effect of the inverter DC to AC ratio on the inverter clipping LOSSES, POWER generation capacity, and on the capacity factor of photovoltaic plant have been investigated.

In this paper, a novel risk-based, two-objective (technical and economical) optimal reactive POWER dispatch method in a wind-integrated POWER system is proposed which is more consistent with operational criteria.  The technical objective includes the minimization of the new voltage instability risk index. The economical objective includes cost minimization of reactive POWER generation and active POWER loss. The proposed voltage instability risk employs a hybrid possibilistic (Delphi-Fuzzy)-probabilistic approach that takes into consideration the operator’s experience, the wind speed and demand forecast uncertainties when quantifying the risk index. The decision variables are the reactive POWER resources of the system. To solve the problem, the modified multi-objective particle swarm optimization algorithm with sine and cosine acceleration coefficients is utilized. The method is implemented on the modified IEEE 30-bus system. The proposed method is compared with those in the previously published literature, and the results confirm that the proposed risk index is better at estimating the voltage instability risk of the system, especially in cases with severe impact and low probability. In addition, according to the simulation results compared to typical security-based planning, the proposed risk-based planning may increase the security and economy of the system due to better utilization of system resources.

Modeling of POWER electronic converters plays a significant role in examining the behaviour and designing control systems. Dual Active Bridge (DAB) converters, due to many advantages such as inherent soft-switching, bidirectional POWER transfer, and higher energy density, are used in various applications such as SST transformers, smart grids, and electric vehicle battery chargers. In this paper, a new reduced-order model for a DAB converter is introduced by modeling nonlinear elements such as semiconductor devices and transformers. By considering all POWER loss elements, and input/output filters, the modeling becomes more realistic. The performance and accuracy of the proposed model is improved compared to conventional reduced-order methods.  Small signal modeling for the DAB converter is curried out and control transfer functions of the system are investigated. Additionally, frequency response analysis of the proposed model under different conditions is compared with the detailed model of the DAB converter containing nonlinear elements implemented in PLECS software. Simulation results demonstrate a satisfactory accuracy of the proposed model in assessing the performance and dynamic behavior of the DAB converter under various operating conditions.

In recent years, using POWER electronic equipment in residential and office buildings, commercial complexes, manufacturing unit's loads such as heating, lighting, domestic appliances have significantly increased. Since, most of them are single-phase with variable load pattern, LV POWER systems are imbalanced and harmonic polluted. The presence of harmonics in imbalance POWER systems can generate vital problems such as excessive neutral current LOSSES and costs. Therefore, a detailed study into these systems is essential. In this paper, instantaneous neutral POWER is used as an indication of identifying imbalances in low voltage systems. By applying Matrix Pencil Method to instantaneous neutral POWER, and based on the rules introduced, the harmonics that have contributions in unbalancing of the system are found. According to this result and according to another set of proposed rules, the loads that affect POWER LOSSES are identified in order to be switched between phases and, further, to optimize the loss in neutral conductor.

The Optimal POWER Flow is one of the fundamental problems in POWER system analyses. Some essential studies in POWER system operation and planning typically require a large number of repetitive OPF solutions. In these analyses, the convergence speed of the OPF solutions beside their accuracy are two key objects. The full ACOPF is accurate, but takes long solution time. The DCOPF is a simple approximation of OPF that is very fast but is not so accurate. This paper presents a method to improve the accuracy of DCOPF, based on evaluating some nodal shares of transmission LOSSES. Like the previous DCOPF, the Modified DCOPF is derived from a non-iterative DC POWER flow, and thus its solution requires no long run time. Moreover, it can simply be realized in the form of Lagrange representation, makes it possible to be considered as some constraints in the body of any bilevel optimization problem, with its internal level including the OPF satisfaction. The efficiency of the Modified DCOPF is illustrated through implementing on three test cases (IEEE 30 & 118 Bus test systems and Iran 2006 Transmission Network) and comparing the results (generation levels, line flows, and voltage angles) with the conventional DCOPF and full ACOPF.