Showing papers by "Graham Town published in 2018"

Integration of electric vehicles and management in the internet of energy

Abstract: Due to the environmental and energy crisis, many countries around the world are electrifying transportation, which will significantly change the way the current power grid operates. It is expected that the deployment of future smart grids will allow two-way energy and information flows through plug-and-play operation of small distributed mobile power generators like electric vehicles (EVs) to benefit the prosumers and at the same time make the grid more efficient and robust. However, the issues associated with the energy and information transfer, battery technologies, battery charging schemes, their standards and management need to be addressed in order to achieve the full benefits of EV integration in the future smart grids and internet of energy (IoE) with local renewable generation. As the current grid with existing infrastructure cannot ensure maximum benefits from EVs, this paper reviews the EV technologies, their connectivity, impacts on grid and standards required for the efficient and economic operation of EVs with distributed energy resources in the IoE. The evolution, comparison, and storage potential of EV technologies are thoroughly discussed. This paper also extensively reviews the connectivity issues, for example current EV charging schemes, software tools required to design smart charging, associated challenges, and possible solutions. The architecture of distributed energy management schemes with EVs and the IoE is discussed in detail. Finally, the standards related to EV integration, energy transfers, and safety aspects are provided. Based on the comprehensive review, future directions are put forward which will be useful for researchers and engineers working with EVs.

Peak-Load Reduction by Coordinated Response of Photovoltaics, Battery Storage, and Electric Vehicles

Abstract: Peak-load management is an important process that allows energy providers to reshape load profiles, increase energy efficiency, and reduce overall operational costs and carbon emissions. This paper presents an improved decision-tree-based algorithm to reduce the peak load in residential distribution networks by coordinated control of electric vehicles (EVs), photovoltaic (PV) units, and battery energy-storage systems (BESSs). The peak-load reduction is achieved by reading the domestic load in real time through a smart meter and taking appropriate coordinated action by a controller using the proposed algorithm. The proposed control algorithm was tested on a real distribution network using real load patterns and load dynamics, and validated in a laboratory experiment. Two types of EVs with fast and flexible charging capability, a PV unit, and BESSs were used to test the performance of the proposed control algorithm, which is compared with that of an artificial-neural-network technique. The results show that using the proposed method, the peak demand on the distribution grid can be reduced significantly, thereby greatly improving the load factor.

Review of solar energy for biofuel extraction

Abstract: One of the most complex challenges of today is managing greenhouse gas emissions produced by excessive use of fossil fuels as energy source. With fossil fuels dominating the energy production, the sustainable and environmental problems will continue unless alternative sources of energy are put in place. Biomass is considered as a promising sustainable energy source which can be introduced to the energy mix. One way of converting raw biomass to higher value biofuels is following the thermochemical conversion processes, which include pyrolysis, gasification, torrefaction, combustion and distillation. However, these processes typically require heat energy to treat the biomass, which is often supplied from non-renewable energy sources. This greatly reduces the conversion efficiency and causes environmental problems. Utilization of solar energy for assisting the biomass conversion through thermochemical conversion process significantly improves the overall sustainability and process performance. This work reviews the solar based technologies and their application to solar assisted biomass utilization and conversion technologies. The review then discusses outcomes of different solar assisted biomass pyrolysis and gasification processes performed to date. It also presents the status of solar assisted distillation for improving ethanol concentration.

A common-ground single-phase five-level transformerless boost inverter for photovoltaic applications

Abstract: This paper presents a transformerless five-level boost inverter with common ground connection for single-phase photovoltaic (PV) systems. It consists of nine switches, two capacitors, and an LC filter at the output. The topology eliminates common mode (CM) leakage current by connecting the negative terminal of the PV directly to the neutral point of the grid, which bypasses the PV array's stray capacitance. As compared to the conventional flying capacitor (FC) multilevel inverter and the cascaded H-bridge (CHB) multilevel inverter, the proposed topology achieves an output voltage that is up to four-times higher given an equivalent dc-link voltage. This reduces the dc-link voltage requirement to one fourth of the values used in conventional multilevel inverters (FC, CHB, NPC, ANPC) and one half of the conventional H-bridge topologies. The following manuscript presents the operation principles and theoretical analysis of the proposed topology, which are supported by simulation and experimental results. A 1 kW prototype was constructed; it achieves 96 % efficiency operating at an output of 240 V AC , 60 Hz, and 973 W.

Waste to Energy Conversion of Chicken Litter through a Solar-Driven Pyrolysis Process

Abstract: Application of solar energy for biomass pyrolysis is a promising technology for converting biomass to energy, fuels, and other chemical substances with neutral CO2 emissions. In comparison to the conventional pyrolysis process, the biomass conversion efficiency can be greatly improved if the pyrolysis heat is supplied from a concentrated solar system, which can be achieved at reasonably moderate solar radiations. This paper discusses fast pyrolysis of chicken litter at different temperatures (560, 760, 860, and 900 °C) supplied from a solar dish of maximum flux density of 69 087 W/m2 under 1000 W/m2 of net (all wave) solar radiation. Yields of the different product fractions (gas, liquid bio-oil, and solid biochar) were assessed using different techniques. The gas yield increased with the temperature from 45.3 wt % at 560 °C to its maximum value of 58.6 wt % at 860 °C. Gas chromatograph results showed CO2, CO, and CH4 as the dominant gases, with contents of 30.2, 22.4, and 2.4 wt %, respectively. When the...

Multifunctional Three-Phase Four-Leg PV-SVSI With Dynamic Capacity Distribution Method

Abstract: The unequal single-phase load distribution in three-phase (3P) four-wire (4W) low-voltage (LV) networks can cause significant neutral current and neutral to ground voltage rise problems at both customer and distribution transformer terminals. High neutral current can overload the neutral conductors and can cause electrical safety concerns to the users. To mitigate the high neutral current problem in an unbalanced residential LV network, a multifunctional 3P four-leg (4L) rooftop photovoltaic (PV) smart voltage source inverter (SVSI) is designed with improved active neutral current compensation along with active power export and point of common coupling (PCC) voltage regulation. A novel dynamic capacity distribution (DCD) method is proposed using the available SVSI capacity after active and reactive power operations to achieve higher capacity neutral compensation at the PCC. The performance of the designed 3P-4L PV-SVSI with the DCD method is compared with a traditional 4L SVSI with fixed unbalanced compensation capacity and a passive unbalance compensator, such as a zig-zag transformer, in PSCAD/EMTDC software. Several case studies, such as balanced and unbalanced load changing effects, are presented with actual residential loads connected to an Australian 3P-4W LV network. A Semikron Semiteach modified inverter and a real-time TMSF28335 DSP microcontroller are also used to provide experimental verification on the improvement of the proposed neutral current compensation with the DCD method. Detailed simulations and experimental studies are presented to verify the robustness and efficacy of the proposed control strategy with the designed 3P-4L PV-SVSI.

A Real-Time Range Indicator for EVs Using Web-Based Environmental Data and Sensorless Estimation of Regenerative Braking Power

Abstract: Most of the commercially available range indicator systems for electric vehicles (EVs) do not provide a sufficiently accurate range to destination, as the environmental factors and driver's behavior are generally not taken into account. In this paper, a real-time range indicator system is developed and implemented using online environmental data from various internet resources to estimate accurately the real-time state of charge and the remaining range for the EV while it is on the road. The estimation considers 1) the dynamic wind speed and wind direction with respect to vehicle position, 2) the probability of rain and ambient temperature, 3) the dynamic effective rolling resistance and terrain adhesion coefficient (based on the condition of the road surface), 4) the time-domain efficiency analysis of the propulsion system, 5) the online traffic conditions and auxiliary loads, and 6) the braking force distribution used in commercially available EVs. The real-time range indicator system is validated using measured data from a 2012 Nissan Leaf driven along a selected route in Australia with the maximum error of 8% for the entire route and less than 1% error at the destination.

Common-ground transformerless inverter for solar photovoltaic module

Abstract: This paper presents a new single-phase transformerless inverter providing common ground for grid-connected photovoltaic (PV) systems. It consists of 5 switches, one diode, one capacitor, one small inductor and a small filter at the output stage. A simple Unipolar Sinusoidal Pulse-Width Modulation (SPWM) technique is used to operate the proposed inverter to minimize losses, output current ripple, filter requirements and improve its electromagnetic compatibility (EMC). The proposed topology shares a common ground with the grid and a capacitor is utilized as a virtual DC bus to provide the negative power cycle of the inverter. The capacitor is charged regardless of any switching cycle using a dedicated switch which can in turn reduce the size of capacitor in relation to the switching frequency. The peak ac output voltage is equal to the input DC voltage which reduces the requirement of the high input DC voltages. Simulation and experimental results for a 1 kW prototype are presented to demonstrate the usefulness of the proposed topology.

An Aperiodic Modulation Method to Mitigate Electromagnetic Interference in Impedance Source DC–DC Converters

Abstract: Rapid voltage and current transitions in switched-mode power converter circuits generate electromagnetic interference (EMI) which may interfere with other electronic systems. High-speed (e.g., wide bandgap) switching devices can improve circuit efficiency and compactness, but may increase the bandwidth of the interference generated. The peak interference is concentrated at harmonics of the fundamental switching frequency, and so may be reduced by modulating the converter switching frequency. However, converter topologies incorporating more than one switching device may not be suited to modulation of the switching frequency, and coordinated modulation of other pulse parameters is required to suppress interference. A relatively simple implementation of a hybrid pulse modulation technique is presented to suppress EMI in a quasi-Z-source converter comprising an impedance-source network and GaN-based H-bridge switching circuit. The technique uses two anharmonically related periodic signals to generate a modulated sawtooth carrier, which in turn generates coordinated switching pulses aperiodically modulated in position and width within a constant switching period. Experimental results demonstrated 10 dB suppression of the peak interference with negligible impact upon the converter's efficiency or output voltage. The proposed pulse modulation technique and its method of implementation are generic, and are expected to be widely applicable to other switched-mode dc–dc power converters.

Scalability of Vehicular M2M Communications in a 4G Cellular Network

Abstract: Automated machine-to-machine communication over cellular wireless networks is likely to become a major source of traffic in future communication networks, e.g., for automated monitoring of infrastructure. The long-term evolution wireless network has been designed to provide enhanced capacity; however, the information rate density that can be accommodated is limited. Here, we report limits to the scalability of automated automobile monitoring systems in terms of delay and blocking rates versus vehicle density. The results of numerical modeling were found to agree well with approximate analytical results.

5.6 Energy Management Softwares and Tools

Abstract: Software tools are reviewed for assisting in the analysis, design, and management of electrical energy systems incorporating renewable energy sources and/or communications for monitoring and control. Over 200 tools are classified by zone, domain, and layer within the CEN-CENELEC-ETSI Smart Grid Reference Architecture. The purpose, availability, source, and application of each tool are briefly described, and a summary of the strengths of selected tools is provided.

Considerations for Integrating PMU Capabilities Into Grid-Connected Power Electronics Converters

Abstract: Information is the pathway to smart electricity distribution grids. Current trends point at phase measurement units (PMUs) becoming the gateway to getting distribution grid information to increase its observability, controllability and monitoring and deliver more advanced grid services and other functionalities. Grid-connected power electronics converters (GCPECs) are ubiquitous in distribution grids as the interface between the grid and distributed generation sources and modern electronic loads. The paper proposes the integration of PMU capability into GCPECs. The cyber-physical systems framework of smart grids is used to illustrate the concepts and benefits of PMU enabled GCPECs. The coordinated initiatives of solar and energy storage GCPECs becoming more grid supportive, providing more information to the grid operators and allowing their direct control by the utilities are summarized as the basis for further development of GCPECs. Finally, the need for communication infrastructure and the potential of using optical sensors for the PMU enabled GCPECs are discussed.