David Whaley

Investigation of switched-mode rectifier for control of small-scale wind turbines

This paper investigates the suitability and experimental testing of a simple power converter for a permanent magnet generator for use with a small-scale variable-speed wind turbine. The controller uses a switched-mode rectifier in conjunction with a high inductance generator that allows generator torque and power to be controlled via the switch duty-cycle. The controller maximises output power for wind speeds below rated, and limits turbine speed for higher wind speeds. Dynamometer and limited wind turbine test results are presented.

Investigation of a Low-Cost Grid-Connected Inverter for Small-Scale Wind Turbines Based on a Constant-Current Source PM Generator

This paper describes a novel low-cost grid-connected inverter for small-scale wind turbines based on a high-inductance PM generator operating in a constant-current output mode. The PM generator is connected to a switched-mode rectifier (SMR) which consists of an uncontrolled rectifier and a switch. The combination of the high-inductance generator and uncontrolled rectifier produces a constant DC current. The switch is used to modulate this current and produces an output current whose fundamental component is a full-wave rectified sinewave and is in-phase with the grid voltage. A line-frequency commutated H-bridge inverter and LC output filter is used to produce a sinusoidal output grid current. The concept is verified using simulations and experimental results

Implementation and performance evaluation of a low-cost current-source grid-connected inverter for PV applications

This paper investigates the performance of a 150 W single-phase current-source grid-connected inverter for PV cells. The constant-current source is realised using a DC link inductor and the inverter is implemented using a single boost switch, a H-bridge inverter and an LC output filter. Although the DC link inductor causes the inverter to be less efficient than an equivalent voltage-source inverter, it offers lower cost due to the zero-current switching and lower number of components. In addition, the output current is easily controlled using the boost switch and simple open-loop control. The inverter input is simulated using the dark I-V configuration of two PV cells. The advantage of this arrangement is the ability to conveniently simulate the PV cell over a wide range of irradiances. The entire system is implemented to verify the simulation results. Furthermore, the paper also examines the proposed inverterpsilas ability to deliver sinusoidal current to the grid whilst meeting the appropriate standards, i.e. total harmonic distortion and power factor requirements. Additionally, the inverterpsilas ability to maximise the PV cell and inverter output power is shown.

Analysis and design of energy storage for current-source 1-ph grid-connected PV inverters

This paper examines the analysis and design of a DC link inductor for a current source 1-ph grid-connected photovoltaic (PV) inverter. Firstly the effect of voltage or current ripple on the PV array average output power is examined using a normalized PV output characteristic. Secondly the design of the inductor and in particular the trade-off between the PV array output power loss and the inductor copper loss are discussed. An inductor was built and a comparison of the calculated and measured loss breakdown is presented.

Energy storage element sizing for single-phase grid-connected photovoltaic converter

Small-scale photovoltaic (PV) systems commonly use single-phase grid-connected (GC) inverters to feed the generated power into the power grid. In this case the instantaneous GC inverter output power shows a 100 Hz fluctuation. However it is required to keep the instantaneous PV array output power as constant as possible to maximise the average PV array output power. Thus all GC inverters use an energy storage component to maintain the instantaneous power fluctuations seen by the PV array at an acceptable level. This paper analyses the relationship between the average power reduction of solar cells and the PV array voltage and current output ripple, and the relationship between the PV array output ripple and the DC link inductor or capacitor sizing.

Sustainable Housing in Australia: Monitored Trends in Energy Consumption

The housing sector in Australia has an escalating share of the national energy consumption. Along with other sectors, the need to reduce energy and greenhouse gas emission in dwellings has been under the spotlight in the last decade. Policy drivers for achieving the desired reduction has comprised progressively more stringent regulations for energy use in buildings and appliances, subsidising energy efficiency features, materials and appliances and supporting exemplar housing developments in partnership with the building industry. The combined approach appears to be producing positive outcomes. After reviewing the Australian domes-tic energy regulatory framework, the paper describes two housing developments which commenced in the late 1990’s and late 2000’s. Both developments involved adherence to specific energy saving targets in individual houses. They were also subjected to rigorous energy monitoring programs. The paper compares the monitored energy consumption patterns of homes in both developments. The detailed monitoring programs also enabled a comparison between energy use patterns for individual appliances including hot water, heating and cooling and lighting. The results demonstrate mostly encouraging trends and highlights potential areas for attention in the future.

Low-pass filter design of a current-source 1-ph grid-connected PV inverter

This paper addresses one of the critical sections of the current-source inverter, the output filter. Firstly, the background of low-pass output line filters for voltage-source inverters (VSI) and current-source inverters (CSI) are provided. Important factors such as filter resonance and damping are explained. Then four different damped CL filter circuits are discussed and the performance of the filter with a grid-connected CSI inverter is analysed. The filter normalisations for the design process are also provided. Finally, the selection of the filter parameters is examined.

Simulation of rooftop photovoltaic shading using TRNSYS

The shade effect of a rooftop photovoltaic (PV) collector on a roof is usually ignored in building energy simulation in Transient System Simulation (TRNSYS) software. This disregard is due to either the unavailability of a suitable shading component in the simulation software or to an assumption that the shade on opaque surfaces, such as roofs, has small impact on the indoor temperature and the subsequent heating and cooling energy usage. However, for a relatively large collector area, ignoring the collector shadow on the roof may produce inaccurate results. In this paper, a novel component is developed in MATLAB to simulate the shade effect of a collector using TRNSYS. The component is based on an isotropic diffuse sky model to calculate the beam and diffuse radiation blocked by the collector. The preliminary results show that 782 degree-hours of cooling can be saved, however, 1649 degree-hours of additional heating is required. The results indicate that for a large collector area the collector shade on the roof should be considered to be able to accurately estimate a dwellings heating and cooling energy usage.

The Life Cycle Cost of Standalone Solar Air-Water Heat Pumps for Australian Homes

To combat increasing electricity prices due to the high operating costs of conventional reverse cycle air-airheat pumps (RC-AA-HP), they can be powered by standalone PV systems as a radical demand side energy management solution. However, the heavy power consumption of their compressors necessitates very large and expensive standalone photovoltaic (PV) systems. Alternatively, reversible air-water heat pumps (RCAW-HP) are integrated with thermal storage units, hence with downsized capacity RC-AW-HP but large thermal storage, the building thermal load can be handled equally. The resultant benefits of standalone PV powered RC-AW-HP, is the potential to need smaller, hence, less costly battery storage. One issue associated with using a standalone PV system is the excess power generated. However, the excess power can be utilized to power domestic heat pump water heater (D-HP-WH) which has a different load profile. Previous researches have not focused on such a system configuration, this study focuses on the techno-economic feasibility of a highly optimized component configuration for such a system to meet the entire all-year round space conditioning and domestic hot water demands of a typical Australian house in three vastly different Australian climatic conditions. The entire system is modelled and simulated in TRNSYS and coupled with GenOpt to carry out the optimization. The lifecycle cost assessment on the most optimized component configuration for 0.2% annual hours loss of load probability in generated electricity, reveal that the twenty years life cycle cost is AU

A Framework for Adaptation of Australian Households to Heat Waves

76,917 in Brisbane, AU