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This paper presents a novel control strategy for the operation of a direct-drive permanent-magnet synchronous-generator-based stand-alone variable-speed wind turbine. The control strategy for the generatorside converter with maximum power extraction is presented. The stand-alone control is featured with output voltage and frequency controller that is capable of handling variable load. The potential excess of power is dissipated in the dump-load resistor with the chopper control, and the dc-link voltage is maintained. Dynamic representation of dc bus and small-signal analysis are presented. Simulation results show that the controllers can extract maximum power and regulate the voltage and frequency under varying wind and load conditions. The controller shows very good dynamic and steady-state performance. Disciplines Physical Sciences and Mathematics

A high penetration of rooftop solar photovoltaic (PV) resources into low-voltage (LV) distribution networks creates reverse power-flow and voltage-rise problems. This generally occurs when the generation from PV resources substantially exceeds the load demand during high insolation period. This paper has investigated the solar PV impacts and developed a mitigation strategy by an effective use of distributed energy storage systems integrated with solar PV units in LV networks. The storage is used to consume surplus solar PV power locally during PV peak, and the stored energy is utilized in the evening for the peak-load support. A charging/ discharging control strategy is developed taking into account the current state of charge (SoC) of the storage and the intended length of charging/discharging period to effectively utilize the available capacity of the storage. The proposed strategy can also mitigate the impact of sudden changes in PV output, due to unstable weather conditions, by putting the storage into a short-term discharge mode. The charging rate is adjusted dynamically to recover the charge drained during the short-term discharge to ensure that the level of SoC is as close to the desired SoC as possible. A comprehensive battery model is used to capture the realistic behavior of the distributed energy storage units in a distribution feeder. The proposed PV impact mitigation strategy is tested on a practical distribution network in Australia and validated through simulations. 2013 IEEE.

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The application of renewable energy such as solar photovoltaic (PV), wind and fuel cells is becoming increasingly popular because of the environmental awareness and advances in technology coupled with decreasing manufacturing cost. Power electronic converters are usually used to convert the power from the renewable sources to match the load demand and grid requirement to improve the dynamic and steady-state characteristics of these green generation systems, to provide the maximum power point tracking (MPPT) control, and to integrate the energy storage system to solve the challenge of the intermittent nature of the renewable energy and the unpredictability of the load demand. In order to improve the efficiency and the power density of the overall circuit, the use of a three-port DC-DC converter, which includes a DC input port for the renewable source, a bidirectional DC input port for the energy storage system, and a DC output port for supplying the load, is a preferable solution to the traditional method using two DC-DC converters: one for the renewable sources and another for the energy storage system. In recent years, many DC-DC three-port converters have been proposed and reported in the literature. Each of these converters has its own topology and operating principle, which results in different complexities, different numbers of components, different reliability and efficiency. In this paper, a comparison of the features of different topologies of three-port DC-DC converters that have been proposed by different research groups is reviewed briefly. This review can be used as a guide for the appropriate selection of the suitable topology to meet the particular requirement of a system. The paper also discusses the potential research extension of the topologies from three-port DC-DC converters to three-port DC-AC inverters and how the voltage gain of the non-isolated three-port DC-DC converter can be improved. A Review of Topologies of Three-Port DC-DC Converters for the Integration of Renewable Energy and Energy Storage SystemNeng Zhang, Danny Sutanto, and Kashem M. Muttaqi School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, New South Wales 2522, AustraliaAbstract: The application of renewable energy such as solar photovoltaic (PV), wind and fuel cells is becoming increasingly popular because of the environmental awareness and advances in technology coupled with decreasing manufacturing cost. Power electronic converters are usually used to convert the power from the renewable sources to match the load demand and grid requirement to improve the dynamic and steady-state characteristics of these green generation systems, to provide the maximum power point tracking (MPPT) control, and to integrate the energy storage system to solve the challenge of the intermittent nature of the renewable energy and the unpredictability of the load demand. In order to improve the efficiency and the power density of the overall circuit, the use of a three-port DC-DC converter, which ...

Utilizing battery storage devices in plug-in electric vehicles (PEVs) for grid support using vehicle-to-grid (V2G) concept is gaining popularity. With appropriate control strategies, the PEV batteries and associated power electronics can be exploited for solar photovoltaic (PV) impact mitigation and grid support. However, as the PEV batteries have limited capacity and the capacity usage is also constrained by transportation requirements, an intelligent strategy is necessary for an effective utilization of the available capacity for V2G applications. In this paper, a strategy for an effective utilization of PEV battery capacity for solar PV impact mitigation and grid support is proposed. A controllable charging/discharging pattern is developed to optimize the use of the limited PEV battery capacity to mitigate PV impacts, such as voltage rise during midday or to support the evening load peak. To ensure an effective utilization of the available PEV battery capacity when used for travel (which is the main usage of the PEVs) or when interventions in the charging operation is caused by passing clouds, a strategy for dynamic adjustments in PEV charging/discharging rates is proposed. The effectiveness of the proposed strategy is tested using a real distribution system in Australia based on practical PV and PEV data. Abstract-Utilizing battery storage devices in Plug-in ElectricVehicles (PEV) for grid support using Vehicle-to-Grid (V2G) concept is gaining popularity. With appropriate control strategies, the PEV batteries and associated power electronics can be exploited for solar photovoltaic (PV) impact mitigation and grid support. However, as the PEV batteries have limited capacity and the capacity usage is also constrained by transportation requirements, an intelligent strategy is necessary for an effective utilization of the available capacity for V2G applications. In this paper, a strategy for an effective utilization of PEV battery capacity for solar PV impact mitigation and grid support is proposed. A controllable charging/discharging pattern is developed to optimize the use of the limited PEV battery capacity to mitigate PV impacts, such as voltage rise during midday, or to support the evening load peak. To ensure an effective utilization of the available PEV battery capacity when usedfor travel (which is the main usage of the PEVs)or when interventions in the charging operation is caused by passing clouds, a strategy for dynamic adjustments in PEV charging/discharging rates is proposed. The effectiveness of the proposed strategy is tested using a real distribution system in Australia,based on practical PV and PEV data.Index Terms-Plug-in Electric Vehicles (PEV), Vehicle-toGrid (V2G), solar photovoltaic impact, distribution network support, charging/discharging control. C Chg-a ,C Chg-

Selection of appropriate climatic variables for prediction of electricity demand is critical as it affects the accuracy of the prediction. Different climatic variables may have different impacts on the electricity demand due to the varying geographical conditions. This paper uses multicollinearity and backward elimination processes to select the most appropriate variables and develop a multiple regression model for monthly forecasting of electricity demand. The former process is employed to reduce the collinearity between the explanatory variables by excluding the predictor which has highly linear relationship with the other independent variables in the dataset. In the next step, involving backward elimination regression analysis, the variables with coefficients that have a low level of significance are removed. A case study has been reported in this paper by acquiring the data from the state of New South Wales, Australia. The data analyses have revealed that the climatic variables such as temperature, humidity, and rainy days predominantly affect the electricity demand of the state of New South Wales. A regression model for monthly forecasting of the electricity demand is developed using the climatic variables that are dominant. The model has been trained and validated using the time series data. The monthly forecasted demands obtained using the proposed model are found to be closely matched with the actual electricity demands highlighting the fact that the prediction errors are well within the acceptable limits. Abstract: Selection of appropriate climatic variables for prediction of electricity demand is critical as it affects the accuracy 10 of the prediction. Different climatic variables may have different impacts on the electricity demand due to the varying 11 geographical conditions. This paper uses multicollinearity and backward elimination processes to select the most appropriate 12 variables and develop a multiple regression model for monthly forecasting of electricity demand. The former process is 13 employed to reduce the collinearity between the explanatory variables by excluding the predictor which has highly linear 14 relationship with the other independent variables in the dataset. In the next step, involving backward elimination regression 15 analysis, the variables with coefficients that have a low level of significance are removed. A case study has been reported in this 16paper by acquiring the data from the state of New South Wales, Australia. The data analyses have revealed that the climatic 17 variables such as temperature, humidity, and rainy days predominantly affect the electricity demand of the state of New South 18Wales. A regression model for monthly forecasting of the electricity demand is developed using the climatic variables that are 19 dominant. The model has been trained and validated using the time series data. The monthly forecasted demands obtained using 20 the proposed model are found to be closely matched with the actual electricity demands highlighting the fact tha...

In this study, a novel high-gain quadratic boost converter with a voltage multiplier circuit is presented to give an alternative power electronic circuit for high-voltage conversion and low-to-medium power applications. The proposed converter combines the traditional quadratic boost converter and a coupled-inductor-based voltage multiplier circuit. Compared with the traditional quadratic boost converter, the proposed converter can obtain a much higher output voltage under the same duty cycle and input voltage, and can also reduce the voltage stresses in the power devices. Moreover, the serious input current ripple in the converter with coupled-inductor is reduced. Consequently, the efficiency and the reliability can be improved by using semiconductors with low-voltage level and high performance. The theoretical analysis of the proposed converter is verified by the experimental results.