Volume 21, Issue 1 -

Electric vehicles (EV) are found to be a good alternative for the conventional internal combustion (IC) engine vehicles in transportation sector due to its various advantages. Now-a-days, wireless charging of EV battery is preferred among the various methods used for charging EV battery. In this paper, extensive review is carried out on various methods used for wireless charging of an EV battery. Different techniques used for transferring power in wireless mode to charge the EV battery are static EV charging technique and dynamic EV charging technique. Static wireless EV battery charging technique adopts inductive and capacitive method for transferring power whereas, dynamic wireless EV battery charging technique adopts only inductive method for transferring power. These techniques are discussed thoroughly in this paper and broad review is carried out with a focus on the compensation circuit topologies, types of core for magnetic coupled inductors, different converters and controllers used for wireless power transfer (WPT) system. Also, design aspects of an static wireless EV battery charging system along with its equivalent circuit analysis is presented in this paper. Challenges and future development in wireless charging of EV battery is also explained in this paper.

Integration of capacitor banks (CBs) and distributed generation units (DGs) in distribution systems aims to elevate the system performance. Optimal sizing and placement of CBs and DGs using Spring Search Algorithm (SSA) is proposed. The SSA aims to attain economic, technical, and environmental advantages. Various objective functions: total emissions produced by generation sources, voltage deviation, total electrical energy cost, and power losses are evaluated. SSA simulates Hawk’s Law among weights and springs. In SSA, agents are weights connected to each other by springs. Performance of the proposed method is evaluated on the IEEE 33-bus system. The results indicate superiority of SSA compared with other optimization algorithms.

Advanced grid technology represented by smart grid and energy internet is the core feature of the next-generation power grid. The next-generation power grid will be a large-scale cyber-physical system (CPS), which will have a higher level of risk management due to its flexibility in sensing and control. This paper explains the methods and results of a study on grid CPS’s behavior after risk. Firstly, a behavior model based on hybrid automata is built to simulate grid CPS’s risk decisions. Then, a GCPS risk transfer model based on cooperative game theory is built. The model allows decisions to ignore complex network structures. On this basis, a modified applicant-proposing algorithm to achieve risk optimum is proposed. The risk management model proposed in this paper can provide references for power generation and transmission decision after risk as well as risk aversion, an empirical study in north China verifies its validity.

The high compensation degree series compensation has a broad development prospects in long distance and large-capacity UHV transmission lines. But it is generating secondary arc current contains low frequency components with high amplitude when the single-phase grounding fault occurs in the series compensated transmission line, which is not conducive to rapid arc extinguishing. To solve this problem, this paper based on the mechanism of generating secondary arc by series compensation transmission lines, and using ATP – EMTP electromagnetic transient program to establish the simulation model of UHV series compensation device. And the suppression effects of small resistance short connection fault series compensation and linkage bypass series compensation measures on secondary arc current and recovery voltage under different series compensation layout mode are studied respectively. The results show that the attenuation speed of the secondary arc current is related to the series compensation arrangement modes and the time when the series compensation device is short connected or bypassed. Series compensation device short connected or bypassed before circuit breaker tripping which can accelerate the arc extinction speed, and the suppression effect is better when the series compensated double platform segmentation layout is distributed on both sides of the line. The results can be used as a reference for the engineering design of UHV with large capacity and long distance and high compensation series compensation transmission lines.

Radial distribution networks are normally protected against fault currents by fuses and reclosers. This protection is coordinated in a way that reclosers clear temporary faults before the melting of fuses and fuses melt to clear permanent faults. Distribution networks, which are recently connected with distributed generations (DGs), incur a variety of issues that are certainly worthy of closer considerations. One of these issues is the operation of protection devices. Recloser-fuse coordination may be lost when DGs are integrated with distribution networks due to the effect of current flowing from DGs during fault period and the breaking of the radiality nature of these networks. The impact of DGs on recloser-fuse coordination depends on penetration level, location, and type of DG. Recloser-fuse coordination of radial distribution networks connected with DGs can be kept by connecting resistive superconducting fault current limiter (R-SFCL) in series with the DG to limit the fault current contribution of DG during the fault period. However, when considering the auto-reclosing scheme of the recloser, recloser-fuse coordination may be lost even if R-SFCL is connected. This paper shows the effectiveness of R-SFCL to restore recloser-fuse coordination without considering auto-reclosing scheme. It also proposes solution methods based on three different configurations of R-SFCL to maintain recloser-fuse coordination when auto-reclosing scheme is considered. Simulation results illustrate the effectiveness of the proposed configurations of R-SFCL to keep recloser-fuse coordination. All simulations are performed using MATLAB/Simulink package.

A comprehensive theoretical investigation validated by the measurement is necessary to assess the impact of a microgrid on the electric distribution system. Some key parameters worth investigating are- enhancing economy, reliability, quality, and resiliency of a microgrid. Considering this necessity, a study of energy delivery system in a microgrid and its financial feasibility to integrate into the energy infrastructure has been presented in this paper. A campus microgrid with energy-efficient combined heat and power (CHP) natural gas-fired microturbine and photovoltaic generation has been used as a testbed to evaluate the efficiency of the power delivery. With distributed control and communication capability, this microgrid can be considered as a building block of smart grid that facilitates the inclusion of renewable and energy-efficient distributed generation. Simulation work has been performed to study the economic feasibility to integrate such microgrid into the energy grid. Several cases of remote microgrid operation have been studied to compare the best possible solution.

In this paper mathematical model for traffic pattern analysis, prediction and resource utilization of Electric Vehicles (EV) in aggregator regions/parking lot zones is proposed. The proposed and presented mathematical model for EV traffic pattern/resource utilization in smart city can be used to estimate the amount of power/voltage available/required by EVs in different aggregator regions. Development of multiagent communication (MAC) based framework for aggregator to EV communication is discussed. V2G aggregation in distribution network forms a Physical part and utility side with sensing/communication forms a Cyber part which combinedly constitutes a Cyber-Physical system. Simulations were carried out on IEEE 33/69 bus test systems using MATLAB and MOBILE C was used for MAC. The results obtained were promising in terms of improved voltage profile and reduced power losses.

Currently, the world is widely introducing renewable energy sources including solar power plants (SPP). In order to predict their work, it is necessary to adequately simulate the processes occurring in solar panels, not only in standard conditions, but also in conditions of partial shading. At present, the effect of partial shadowing is considered from the point of view of changes in the luminous flux, however, for a more adequate and comprehensive simulation, it is also necessary to take into account the temperature change in the shaded areas of SPP, especially considering the area of powerful SPP, the temperature of individual sections of which can radically differ, which is undoubtedly will lead to a change in the output characteristics of the SPP. Failure to take this factor into account, when modeling high-power SPP leads to results that do not correspond to real data.

Recently, the voltage stability and control of distribution networks become challenges due to the large line impedance, load variations and particularly the presence of distributed generation. This paper presents a coordinated voltage control scheme of distribution systems with distributed generation based on on-load tap changer and shunt capacitors. The problem is to determine the optimal operation of voltage regulation devices to minimize a multi-objective function including power losses, voltage deviations and operation stresses while subject to the allowable voltage ranges, line capacity and switching stresses, etc. The problem is formulated and solved by a modified particle swarm optimization algorithm to treat the large-scale and high nonlinearity property. The proposed scheme is applied to a typical 48-bus distribution network in Vietnam. The result of simulation shows that the voltage profile can be improved while the power loss of distribution systems can be reduced significantly.

This paper proposes a load frequency control (LFC) scheme for the distributed generation (DG) system of the microgrid (μ-grid) using the D-partition method (DPM). μ-grid is formed with a combination of renewable and non-renewable sources to supply distribution system loads of smaller capacity. In this research paper, μ-grid comprising of a combination of a wind turbine generator (WTG) and Diesel Generator (DG) are taken for investigation of LFC. For the effective control of real power generation of μ-grid, Proportional-integral (PI) controllers are implemented for WTG and DG system so that the frequency deviation is minimized. The PI controller parameters found by using DPM are compared with the conventional Ziegler-Nichols method (ZNM). The main contribution of this work is to provide a single step /simplistic computing method for calculating the PI controller parameters of a dynamic system such as the microgrid system comprising of the renewable energy sources without any further requirements of retuning. Simulation results demonstrate the robustness of the DPM, which is superior in damping frequency oscillations of μ-grid.

In transformers, in addition to the primary and secondary coils, there are several other important components and accessories in which the insulating material is one of the most critical components of a transformer. Sufficient insulation between different active parts are necessary for safe operation. Adequate insulation, it is not only necessary to insulate the coils from each other, or from the core and tank, but also guarantees the safety of the transformer against accidental surges, but with the growth in size and complexity of power stations, transformer is facing insulation problems. The evaluation of the transformer overload capacities certainly leads to complex variables that affect the operating life of the power and distribution transformer. In this study, the long-life calculation is performed on the basis of two experiments, which are related to the insulation degradation of the mineral oil and cellulose paper such as by adding different types of nano-particles to the mineral oil to enhance the strength of oil, and by changing the loads under different operating conditions to control the deteriorating rate of the insulation to prevent the life of the transformer. The insulation breakdown strength is improved from 37 kV to 71 kV by mixing the semiconductor nanoparticles such as gadolinium-doped ceria (GDC) and cerium dioxide (CeO2) with mineral oil. Moreover, for cellulose paper, thermal degradation rate is kept below its limit by reducing the temperature when controlling the load.