title: Supercapacitor assisted power converter for DC microgrid applications with self-contained DC-UPS capability

authors: Hu, Yang

subjects: DC microgrid

abstract: Nowadays, due to the advantages inherent in using renewable energy, renewable power generation is becoming established worldwide. Direct current (DC) microgrid systems, which have been proposed as alternatives for traditional alternating current (AC) networks, enable the introduction of a large amount of solar energy by using distributed photovoltaic generation units. Meanwhile, small-scale DC microgrid systems designed at the household level are also viable options used to harness renewable energy (like solar energy) and have broad development prospects.
One of the ‘hot topics’ in the field of renewable energies is how to make efficient use of this type of energy. In this thesis, a high-efficiency DC microgrid system with supercapacitor (SC)-assisted power converter is introduced as a way to harness solar energy to run a 12 V, 50 W household lighting system.
Supercapacitor-assisted low dropout regulator (SCALDO) techniques were used to build an SC-assisted converter for a DC microgrid system. Supercapacitors in the DC microgrid acted as voltage droppers to convert 24 V solar panel’s output to 11 V – 13 V. Supercapacitors were also used as energy storage devices, and performed as a power source to run the household lighting system for a period of time after a sudden mains power outage.
Real weather condition data, including local Hamilton illuminance values, were required to design this system. These data were measured at the University of Waikato. They were converted into irradiance data and were used to create similar patterns for simulation. Prototype circuit of the complete DC microgrid system, with an SC-assisted converter was also developed and shown at the end of the thesis.

text: Supercapacitor assisted power converter for DC microgrid applications with self-contained DC-UPS capability Nowadays, due to the advantages inherent in using renewable energy, renewable power generation is becoming established worldwide. Direct current (DC) microgrid systems, which have been proposed as alternatives for traditional alternating current (AC) networks, enable the introduction of a large amount of solar energy by using distributed photovoltaic generation units. Meanwhile, small-scale DC microgrid systems designed at the household level are also viable options used to harness renewable energy (like solar energy) and have broad development prospects.
One of the ‘hot topics’ in the field of renewable energies is how to make efficient use of this type of energy. In this thesis, a high-efficiency DC microgrid system with supercapacitor (SC)-assisted power converter is introduced as a way to harness solar energy to run a 12 V, 50 W household lighting system.
Supercapacitor-assisted low dropout regulator (SCALDO) techniques were used to build an SC-assisted converter for a DC microgrid system. Supercapacitors in the DC microgrid acted as voltage droppers to convert 24 V solar panel’s output to 11 V – 13 V. Supercapacitors were also used as energy storage devices, and performed as a power source to run the household lighting system for a period of time after a sudden mains power outage.
Real weather condition data, including local Hamilton illuminance values, were required to design this system. These data were measured at the University of Waikato. They were converted into irradiance data and were used to create similar patterns for simulation. Prototype circuit of the complete DC microgrid system, with an SC-assisted converter was also developed and shown at the end of the thesis.

year: 2017

title: Pyrite geochemistry and textures in the epithermal Au-Ag mineralisation at Waihi

authors: Eames, Anna G.

abstract: The Waihi epithermal system is a low sulphidation epithermal system that hosts one of the largest high grade ore deposits in the Southern Hemisphere. The use of petrographic and EPMA analyses demonstrate there are distinctive textural zones within pyrite grains that vary in chemistry and appearance. Some of these zones contain elevated concentrations of Au and Te, and varying concentrations of Fe, S, Cu, Pb or Zn. The textural observations indicate that in some samples, pyrite growth was interrupted by periods of dissolution. Grains begin growth with overall low trace element concentrations, with the highest concentrations of trace elements occurring in the middle phase of the grain’s growth. Inclusions are rich in Pb, Ca, Se, Zn and Ni, and are attributed to the ‘dirty’ texture of some samples. Inclusion-rich areas are also high in Au. The nature of the presence of Te suggests either a single source of magmatic fluid, released in pulses, or periodical dilution of the magmatic fluid by meteoric waters.

text: Pyrite geochemistry and textures in the epithermal Au-Ag mineralisation at Waihi The Waihi epithermal system is a low sulphidation epithermal system that hosts one of the largest high grade ore deposits in the Southern Hemisphere. The use of petrographic and EPMA analyses demonstrate there are distinctive textural zones within pyrite grains that vary in chemistry and appearance. Some of these zones contain elevated concentrations of Au and Te, and varying concentrations of Fe, S, Cu, Pb or Zn. The textural observations indicate that in some samples, pyrite growth was interrupted by periods of dissolution. Grains begin growth with overall low trace element concentrations, with the highest concentrations of trace elements occurring in the middle phase of the grain’s growth. Inclusions are rich in Pb, Ca, Se, Zn and Ni, and are attributed to the ‘dirty’ texture of some samples. Inclusion-rich areas are also high in Au. The nature of the presence of Te suggests either a single source of magmatic fluid, released in pulses, or periodical dilution of the magmatic fluid by meteoric waters.

year: 2016

title: A path to lotions and potions: Ngāti te Maunga ahi kā use of rongoā for hapū wellbeing

authors: Diamond, Kiri

subjects: rongoā

abstract: The research aimed to determine the challenges and improvements required during the implementation of the rongoā programme. The rongoā programme was based on a papakāinga near a marae, in a semi-rural location with difficult access. Participatory action research and autoethnography methods were used with the ahi kā (local residence) to develop a programme that would fulfil the hapū ora (extended family wellbeing) goals.  The goals of the programme were: for the ahi kā to use rongoā (modalities of health) confidently for their wellbeing; consistently use a Facebook page to learn and share information and to develop a database of the local rongoā rākau (medicinal plant). The ahi kā identified a further question to ask Facebook members to understand what motivated their participation and a survey was conducted. The ahi kā also wanted to understand the local doctor’s view on rongoā and its context on health provision in their area. An interview was conducted and the survey and interview added to the understanding of what the ahi kā could do to improve theirs and the hapū whānau (group extended family) wellbeing.
The findings of the research highlighted the complexities that arise from conducting research in a bicultural space where a common understanding of cultural knowledge is assumed to be homogenous. A shared history with colonisation and religious beliefs brought to the forefront the multiplicity Māori work through to determine a shared hapū identity. Based on an understanding of Māori principle values and tikanga (ways of enacting values), as understood by ahi kā, transformed a programme of learning how to make lotions and potions for the ahi kā, into influencing hapū members to change their attitudes and behaviours to their environment and their wellbeing.
This research highlighted the role that ahi kā hold as keepers of cultural knowledge that is rooted in the papakāinga through ancestral links that informs the identity of a hapū. Learning how to use rongoā provided ahi kā a platform to learn a new skill while helping the hapū heal through connecting with the identity and land of the hapū they belong to.

text: A path to lotions and potions: Ngāti te Maunga ahi kā use of rongoā for hapū wellbeing The research aimed to determine the challenges and improvements required during the implementation of the rongoā programme. The rongoā programme was based on a papakāinga near a marae, in a semi-rural location with difficult access. Participatory action research and autoethnography methods were used with the ahi kā (local residence) to develop a programme that would fulfil the hapū ora (extended family wellbeing) goals.  The goals of the programme were: for the ahi kā to use rongoā (modalities of health) confidently for their wellbeing; consistently use a Facebook page to learn and share information and to develop a database of the local rongoā rākau (medicinal plant). The ahi kā identified a further question to ask Facebook members to understand what motivated their participation and a survey was conducted. The ahi kā also wanted to understand the local doctor’s view on rongoā and its context on health provision in their area. An interview was conducted and the survey and interview added to the understanding of what the ahi kā could do to improve theirs and the hapū whānau (group extended family) wellbeing.
The findings of the research highlighted the complexities that arise from conducting research in a bicultural space where a common understanding of cultural knowledge is assumed to be homogenous. A shared history with colonisation and religious beliefs brought to the forefront the multiplicity Māori work through to determine a shared hapū identity. Based on an understanding of Māori principle values and tikanga (ways of enacting values), as understood by ahi kā, transformed a programme of learning how to make lotions and potions for the ahi kā, into influencing hapū members to change their attitudes and behaviours to their environment and their wellbeing.
This research highlighted the role that ahi kā hold as keepers of cultural knowledge that is rooted in the papakāinga through ancestral links that informs the identity of a hapū. Learning how to use rongoā provided ahi kā a platform to learn a new skill while helping the hapū heal through connecting with the identity and land of the hapū they belong to.

year: 2019