Large scale of plug-in electric vehicles(PEVs) integration will pose inevitable impacts on the planning and operation of power system in the future.The literature reviews were carried out on PEVs integration on power system including PEVs charging load modeling,simulation and calculation,PEVs' impacts on power system,and control and utilization of PEVs charging and discharging.Firstly,key factors when analyzing the charging load were pointed out.Additionally,the impacts of PEVs integration on generation expansion,grid operation,charging facilities and distribution system planning were discussed.The current research on coordinated charging of PEVs and "vehicle-to-grid(V2G)" operation were reviewed as well.Finally,possible future research areas were presented.

Impacts and Utilization of Electric Vehicles Integration Into Power Systems

Self-adaptive differential evolutionary extreme learning machines for long-term solar radiation prediction with remotely-sensed MODIS satellite and Reanalysis atmospheric products in solar-rich cities

MVDC technology is a promising solution to avoid installation of new AC networks. MVDC can provide optimum integration of large-scale renewable energy sources, the interconnection of different voltage levels of DC and AC grids with the ancillary services. The development in MVDC depends significantly on the DC-DC converters. Such converters support the modern trends of utilising medium-frequency transformers in power networks. Research on isolated converters technology is in its infancy and limited by the conversion ratio and component ratings. Besides, there is no standards exist covering specific aspects of isolated converter product. Thus, a review of such converters is needed. This work presents, for the first time, a review of the DC-DC power converter families in MVDC grids including the leading families which are isolated and non-isolated converters, as well as other subfamilies comparing the specifications and characteristics. Also, the applications of these converters are provided by focusing on the essential requirements for each application.

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Isolated and Non-Isolated DC-to-DC Converters for Medium Voltage DC Networks: A Review

Recently, more occasions with high input voltage and/or high output voltage applications are emerging. However, the existing switching devices are limited by the voltage stress, e.g., the available maximum blocking voltage of insulated-gate bipolar transistors is 6.5 kV. Therefore, several methods are provided to solve this issue, including series connection of switches, multilevel converters, and modular series–parallel structures, where the modular series–parallel systems are the most popular choice due to the advantages of low cost, simple design process, high modularity, reliability, and redundancy. The main objective of series–parallel systems is to ensure the sharing of input/output voltage/current. Based on this, a comprehensive review on the available voltage/current sharing methods for series–parallel systems, which include input-series output-parallel, input-parallel output-series, and input-series output-series structures is provided in this article. Moreover, the relationships between the input voltage/current sharing and output voltage/current sharing of series–parallel systems are explained.

A Review of Voltage/Current Sharing Techniques for Series–Parallel-Connected Modular Power Conversion Systems

The electrical power system has experienced several changes during the last decade, raised by continuously increasing load demand, rapid depletion in fossil fuels, and newly electrical deregulation policy. In the past, numerous review literatures has been published in the field of Load Frequency Control (LFC), which deals with different and recent control strategies for the successful operation of the power system. Moreover, due to changes in lifestyle, increasing load demand, expansion of industrialization, and environmental issues, Renewable Energy Sources (RES) integration becomes the obvious adaptive choice. Since generation from RES is stochastic in nature and depends upon the weather condition and other aspects at every instant of time. Therefore, high penetration may reflect specific issues regarding voltage instability, frequency stabilization, and reliability obstruction. Hence this issue has been covered effectively in this review work. Furthermore, the work precisely summarized and briefly explained the different scenarios of Energy Storage (ES), micro-grid and Flexible AC Transmission System (FACTS) to explore the possible solutions and future aspects. The merit and demerit of different controllers are also investigated with the help of a comparison's tables and also some other analytical comparisons. The overall study examines an in-depth review of recent technical core aspects for LFC based on classical and modern power system which involves the non-linear model, controller design parameters, soft-computing application, attributes of Load forecasting, as well as integration of RES in a deregulated environment. This effective, comprehensive literature survey is very helpful for researchers to bridge the gap between recent development, implementation, challenges and future trends of RES in LFC. 

A literature survey on load frequency control considering renewable energy integration in power system: Recent trends and future prospects

Demand responsive charging strategy of electric vehicles to mitigate the volatility of renewable energy sources

Optimal charging strategy for electric vehicles in residential charging station under dynamic spike pricing policy

In this paper, a fully modular control strategy for input-series output-parallel (ISOP) inverter system is proposed to ensure equal sharing of input voltage and output current among the constituent inverters. Compared with existing control strategies, such as centralized control that restricts the modularity of the system and distributed control, which realizes voltage and current sharing by means of connecting constituent inverter modules through sharing buses, the proposed control strategy can achieve fully modular design without any control signal interconnection among the constituent inverters, leading to superior modularity and reliability. First, the control strategy is deduced and the principle of the control strategy is analyzed. Then, the detailed implementation and stability analysis of the proposed strategy are presented. At last, a two-module ISOP inverter system is tested in the laboratory and the experimental results verify the effectiveness of the proposed control strategy.

A Fully Modular Control Strategy for Input-Series Output-Parallel (ISOP) Inverter System Based on Positive Output-Voltage-Amplitude Gradient

A novel hybrid resonant zero-voltage zero-current switching three-level converter with capacitive output filter is proposed in this paper, which undergoes half of the input voltage for switches and is suitable for offshore wind farms in medium-voltage dc (MVDC) collection systems. The proposed converter, utilizing two transformers with very different power ratings, adopts insulated-gate bipolar transistors for all six power switches and operates in discontinuous current mode and can achieve zero-current switching for the four main switches and rectifier diodes over the whole load range. Meanwhile, the auxiliary switches with small current rating can realize zero-voltage switching naturally. Hence, the switching loss is reduced, which is vital in MVDC applications. By the trajectory formulas of the resonant current and voltage, the trajectory paths can be achieved, which is helpful to compare the peak and turn- off currents of switches. The design rules of main parameters can be deduced with the trajectory formulas and paths. The influence of the turns ratio of auxiliary transformer and the resonant capacitance on the peak and turn- off currents is discussed in detail. The operation principles of the proposed converter are analyzed and verified by the simulation and experimental results.

A Hybrid Resonant ZVZCS Three-Level Converter for MVDC-Connected Offshore Wind Power Collection Systems

A resonant zero-voltage and zero-current-switching (ZVZCS) dc–dc converter is proposed in this paper for a medium-voltage dc collection system of offshore wind farms. The resonant converter is composed of two full-bridge cells sharing a bridge leg, two transformers with uneven power ratings and different functions, whose secondary windings are connected in series and a voltage-doubler rectifier. The converter operates in discontinuous current mode and can achieve zero-current switching for four main power switches and rectifier diodes over the whole load range. The two auxiliary switches with small forward current can be turned on with ZVZCS, and turned off with zero-voltage switching. Hence, the switching loss can be reduced and efficiency is improved. The operation principle of the converter is analyzed and design rules of main parameters are presented. The influences of the turn ratios of auxiliary transformer and resonant capacitance on the peak and switching-off currents are discussed in detail. Furthermore, a model is built in PLECS and simulation results are given. A 150–1500 V/2 kW prototype is established and tested to verify the operation principle and design rules.

Wu Cao

Papers

Demand responsive charging strategy of electric vehicles to mitigate the volatility of renewable energy sources

Optimal charging strategy for electric vehicles in residential charging station under dynamic spike pricing policy

A Fully Modular Control Strategy for Input-Series Output-Parallel (ISOP) Inverter System Based on Positive Output-Voltage-Amplitude Gradient

A Hybrid Resonant ZVZCS Three-Level Converter for MVDC-Connected Offshore Wind Power Collection Systems

A Resonant ZVZCS DC–DC Converter With Two Uneven Transformers for an MVDC Collection System of Offshore Wind Farms