Techno-economic analysis of multiple paralleled diesel generators for micro isolated applications

Conference ProceedingsThis paper analyses the key benefits of a multiple paralleled diesel generator system over a "Single" diesel generator system for supplying small remote and isolated loads. Even though having several small diesel generators in parallel instead of one larger one will certainly induce higher capital cost of the generating unit, the resulting cost of kWh generated as well as the system is life cycle cost can be significantly decreased . In this study, HOMER Pro software is used to compare the technical, economic and environmental performance of the two configurations. For the selected case study, the simulation results reveal that multiple connected small diesel generators instead on a single large one can be considered for rural and isolated electricity generation

Optimized scheduling of diesel - renewable systems with pumped hydro storage

Published Conference ProceedingsThe present paper develops a model to optimize the daily operation of a hybrid energy system consisting of a photovoltaic unit, a wind unit, a pumped hydro storage system and a diesel generator. The main purpose of the developed model is to minimize the hybrid system’s operation cost while optimizing the system’s power flow considering the different component’s operational constraints. The simulations have been performed using “fmincon” implemented in Matlab. The model has been applied to two test examples; the simulation results are analyzed and compared to the case where the diesel generator is used alone to supply the given load demand. The results show that using the developed control model, fuel saving can be achieved compared to the case where the diesel is used alone to supply the same load patters

A SURVEY OF DOMESTIC WATER HEATING TECHNOLOGIES

ProceedingsConference: ProceedingsIn South Africa, heating water for domestic use is one of the most energy consuming processes in residential buildings. This process represents up to 60% of the total energy in the residential sector. Using more efficient and improved technologies to heat domestic water can make a positive contribution to the fight against the country’s current energy crisis which has a direct implication on the yearly increase in electricity prices. The purpose of this paper is to conduct a survey, summarize and critically analyze the different technologies used to heat water for domestic purposes. The results of this survey aim to identify gaps in the existing research, especially in the case of South Africa. Several research papers and other academic studies are reviewed and classified based on their focus, contribution and the type of technology to achieve a comfortable thermal level of water for domestic use. The key findings indicate importance of implementing hybrid systems for increased reliability and hot water availability while minimizing operating costs

COOLING PHOTOVOLTAIC SYSTEMS: A SURVEY OF AVAILABLE TECHNOLOGIES

ArticleCooling is a key operation factor to take into consideration to achieve higher efficiency when operating solar photovoltaic systems. Proper cooling can improve the electrical efficiency, and the heat removed by the cooling system can be used in other domestic, commercial or industrial applications. This paper is a survey of various methods that can be used to minimize the negative impacts of the increased temperature while making an attempt to enhance the efficiency of photovoltaic solar panels operating beyond the recommended temperature from the Standard Test Conditions (STC). These technologies are discussed based on their operation principles, technical advantages, and disadvantages. The results of this study highlight that any technology selected to cool a photovoltaic panel should be used to keep the operating surface temperature low and steady, be simple and reliable and, if possible, enable the use of extracted thermal heat to enhance efficiency of the overall conversion system

IMPACT OF DIFFERENT LOAD PROFILES ON SIZING AND PERFORMANCE OF A MICRO-HYDROKINETIC-BATTERY BASED HYBRID SYSTEM

Conference ProceedingsHydrokinetic hybrid systems are gaining more interest since hydrokinetic technology has proved to offer a cost-effective electrification solution. Very few research studies on sizing and optimization of micro-hydrokinetic-battery (MHK-B) based hybrid systems have been done. However, the authors did not explore the impact of different load profiles on optimal sizing and performance of the MHK-B hybrid system. In this study, the impact brought by different load profiles such as residential, commercial and industrial sectors on sizing and operation of a river based MHK-B hybrid system is investigated using Hybrid Optimization Model for Electric Renewable (HOMER) software. HOMER Pro version 3.6.1 has been selected since it is equipped with hydrokinetic turbine module. The flowing water resource data obtained from a typical river of South Africa has been used as an input. Sample of load profile curves for residential, commercial, industrial have been used to estimate the daily load demands. The optimum configuration results indicated that for the same daily energy consumption, the type of a load profile affects the battery storage capacity, hydrokinetic turbine size, inverter and rectifier operational hours as well as the annual excess energy for the MHK-B hybrid system

Grid-interactive micro-hydrokinetic with pumped-hydro storage: The case study of three South African demand sectors

Conference ProceedingsThis paper investigates the operation of different demand sector such as residential, commercial and industrial load profiles when supplied with a grid tied micro-hydrokinetic pumped-hydro storage (MHK-PHS) hybrid system. The aim is to explore the demand sector which is more favorable to the proposed grid-tied MHK-PHS hybrid system under the time-of-use (TOU) tariff scheme. Hence, the optimum configuration of the proposed MHK-PHS hybrid system is determined in order to investigate the effect of each demand sector on sizing and operation of the hybrid system. HOMER Pro Version 3.6.1 has been used to perform the optimization under TOU tariff scheme. The results have shown that the industrial load sector incur the lowest cost of energy at the highest capital cost as opposed to the residential and commercial load sectors. However, from economic perspective, the residential demand sector proved to be more favorable to the proposed hybrid system due to the lowest net present cost (NPV). For each load demand sector, HOMER led to oversizing constraint of the hybrid system by not recharging the storage system after use

Hydro aeropower, an option for electricity cost reduction in farming applications

Conference ProceedingsThis paper develops a model which can be used to minimize the electricity cost of South African farms through the usage of a wind pump with pico hydro generator and a borehole in pumped hydro storage configuration referred to as “hydro aeropower”. This model will optimally schedule the generation power flow from the pico turbine given the demand, the state of water level in the reservoir as well as the electricity pricing period. This model can be implemented to control the power flow in small farming activities where boreholes and windmill are available. Therefore, the wind and groundwater resources can be effectively used to locally produce electricity which can contribute to the decrease of the systems’ total operation costs

Modelling and simulation of a power converter for variable speed hydrokinetic systems

Conference ProceedingsThis study presents the control scheme model of a micro-hydrokinetic turbine system equipped with a permanent magnet synchronous generator (PMSG). A power conversion system model is developed to allow a variable speed hydrokinetic turbine system to generate constant voltage and frequency at variable water speeds. A DC-DC boosting chopper is used to maintain constant DC link voltage. The DC current is regulated to follow the optimized reference current for maximum power point tracking (MPPT) operation of the turbine system. The DC link voltage is controlled to feed the current into the load through the line-side pulse width modulation (PWM) inverter. The proposed scheme is modelled and simulated using MATLAB/Simulink. The results show a high quality power conversion solution for a variable speed hydrokinetic river system

A survey of differential flatness-based control applied to renewable energy sources

Conference ProceedingsThis paper presents an overview of various methods used to minimize the fluctuating impacts of power generated from renewable energy sources. Several sources are considered in the study (biomass, wind, solar, hydro and geothermal). Different control methods applied to their control are cited, alongside some previous applications. Hence, it further elaborates on the adoptive control principles, of which includes; Load ballast control, dummy load control, proportional integral and derivative (PID) control, proportional integral (PI) control, pulse-width modulation (PWM) control, buck converter control, boost converter control, pitch angle control, valve control, the rate of river flow at turbine, bidirectional diffuser-augmented control and differential flatnessbased controller. These control operations in renewable energy power generation are mainly based on a steady-state linear control approach. However, the flatness based control principle has the ability to resolve the complex control problem of renewable energy systems while exploiting their linear properties. Using their flatness properties, feedback control is easily achieved which allows for optimal/steady output of the system components. This review paper highlights the benefits that range from better control techniques for renewable energy systems to established robust grid (or standalone generations) connections that can bring immense benefits to their operation and maintenance costs

A review of solar photovoltaic systems cooling technologies

Published ArticleCooling the operating surface is a key operational factor to take into consideration to achieve higher efficiency when operating solar photovoltaic systems. Proper cooling can improve the electrical efficiency, and decrease the rate of cell degradation with time, resulting in maximisation of the life span of photovoltaic modules. The excessive heat removed by the cooling system can be used in domestic, commercial or industrial applications. This paper presents a review of various methods that can be used to minimize the negative impacts of the increased temperature while making an attempt to enhance the efficiency of photovoltaic solar panels operating beyond the recommended temperature of the Standard Test Conditions (STC). Different cooling technologies are reviewed, namely Floating tracking concentrating cooling system (FTCC); Hybrid solar Photovoltaic/ Thermal system cooled by water spraying; Hybrid solar Photovoltaic/ Thermoelectric PV/TE system cooled by heat sink; Hybrid solar Photovoltaic/Thermal (PV/T) cooled by forced water circulation; Improving the performance of solar panels through the use of phase-change materials; Solar panel with water immersion cooling technique; Solar PV panel cooled by transparent coating (photonic crystal cooling); Hybrid solar Photovoltaic/Thermal system cooled by forced air circulation, and Solar panel with Thermoelectric cooling. Several research papers are reviewed and classified based on their focus, contribution and the type of technology used to achieve the cooling of photovoltaic panels. The discussion of the results has been done based on the advantages, disadvantages, area of application as well as techno-economic character of each technology reviewed. The purpose of this review is to provide an understanding for each of the above-mentioned technologies to reduce the surface temperature of the PV module. The study will focus on the surface temperature reduction array bound by each of the cooling technologies. The performance of each cooling technology will also be highlighted. In addition to this study, this review will include a discussion comparing the performance of each cooling technology. The outcomes of this study are detailed in the conclusion section. This paper has revealed that any adequate technology selected to cool photovoltaic panels should be used to keep the operating surface temperature low and stable, be simple and reliable and, if possible, enable the use of extracted thermal heat to enhance the overall conversion efficiency. The presented detailed review can be used by engineers working on theory, design and/or application of photovoltaic systems