1,721,011 research outputs found
Battery energy storage system control algorithm design
Get PDFMicrogrid is based on smaller decentralised low voltage system with the use of modern power technology puts different types of Distributed Energy sources solar power, wind power, and energy storage devices together, improving the electrical supply reliability, reducing the feeder loss and ensures the stability of the voltage. The current trend of incorporating energy storage devices in the microgrid is aimed to mitigate the power imbalance and improve the electrical supply reliability. The thesis uses Kalbarri, Western Australia as a case study site with an aim to investigate the appropriate battery technology and formulate control algorithm for the microgrid.
The thesis starts by examining the Australian electrical market including the: socio‐economic, political, and regulatory environment and presents the rationale of having an Energy Storage System in rural Australia. The thesis investigates the various available BESS battery technology options and suggests the most appropriate options for the BESS comprised Kalbarri microgrid model. The MATLAB/Simulink BESS control algorithm design model is presented with an aim to test voltage and frequency regulation under different load condition, including the process of seamless transition from the grid‐connected operation to a grid‐disconnected operation of the microgrid.
The research presents a theoretical control model based on the Power Control theory and existing academic literature on the topic. The thesis examines the control algorithm design to regulate the frequency and voltage using the BESS system to connect to the main three phase AC grid. The overall site model includes a power conversion of two DC sources: BESS and PV system. The BESS control algorithm model comprises of a Power Conversion system that use three‐phase full bridge Insulated Gate Bipolar Transistors (IGBTs) with LCL filter and a Power Control System based on Phased Lock Loop to synchronise with the grid frequency. The Power Control system uses a three‐phase sinusoidal abc frame conversion to a DC reference signal dq0 frame to incorporate PI controller with an aim that the intermittence of the renewable energy generation Wind and PV system can be maintained to a balanced state in the grid within a short frame of time. The BESS control algorithm model uses a Current Controlled Voltage Source Converter for its simple controller design, better performance during grid fault and the overall cost saving of the system. The thesis simulation utilized CCVSC for its tight regulation of the line current, mainly VSC protection against overcurrent and a high accuracy instantaneous current control.
However, the author acknowledges the simulation result indicate an anomaly with voltage control while using CCVSC in the control algorithm model in power source transition test condition. Hence, as a part of future improvement with a focus on the overcurrent, the author concludes possible testing with the VCVSC based control algorithm model for rapid and continuous response for smooth dynamic control and automated P and Q power control in both steady‐state and dynamic system conditions.
Finally, the impact on the microgrid is presented with an in‐depth analysis of the results, including the achievements, innovations, challenges and the suggestion for future improvement in the discussion section of the report
Cost-effective solution for electric micro-grid in Rottnest Island
Get PDFMicrogrids are a relatively recent technology, but the concept has been around for a long time. Since the first power system built in 1881, power systems have experienced substantial changes leading to the current networks where all the electrical energy is produced in large plants that are heavily dependent on fossil fuels, hydro and sometimes nuclear power (Ernst 2014). Micro grids have always been in existence but the technology to implement them on a large scale has limited micro grids from flourishing.
Rottnest Island is a notable example of a place currently implementing the use of a hybrid micro-grid (HMG) on a large scale. Up until recently, the island was solely dependent on diesel generators for electricity, in 2004 a 600kW wind turbine was added to supplement the electricity energy produced by generators and offset some diesel fuel consumption. Due to the high costs of shipping diesel into the island, The Rottnest Island Authority (RIA) decided to upgrade the island’s electrical network by incorporating a 600-kW photovoltaic system into the network and upgrading the existing water treatment plant as the RIA had recorded increasing levels of salt levels in the island’s underground water.
This research evaluates multiple aspects of running the upgraded hybrid solar-wind-diesel micro-grid and how the levelised cost of electrical energy production can be reduced by using Homer software to analyse the island’s electrical load profile and using the data to assess every possible system combination. The current setup of the network is quite inefficient as there is excess power being produced which is then being sent to a dump load. The results have been conclusive in terms of finding better combinations that will not only increase the reliability of the HMG but also reduce the overall LCOE. Storage capabilities in the network would be advantageous not only in reducing the LCOE but also producing a high quality of power while also increasing the overall stability of the network.
Further simulations were conducted to include a theoretical load into the existing system. This was view as a theoretical thermal load that simulates the idea of hot water storage for the island. The thermal load was designed in a way that it would consume any excess energy being generated in the system to heat up water for later usage.
The conclusion has been that while the current HMG setup is functional and environmentally friendly, the LOCE of the overall network is high and impractical. For the current design of the microgrid, a lot of energy is wasted, which is energy that can be utilised by incorporating components such as storage devices or maybe utilising the already existing desalination plant to heat and store hot water. These components could help reduce the number of diesel generators used and utilises most of the electricity generated by the renewable energy sources
Impact of high renewable penetration in a distribution network
Get PDFThe growth of renewable energy, especially PV system has been accelerated in the past decades. With this growth, several problems have been identified that can interfere with the power quality on the distribution network. These problems include; voltage rise, voltage unbalance, voltage sag/swell, flickering, and harmonic issue. IEEE 13 bus distribution network has been chosen to be the base of this research due to its flexibility and it has been modeled in DigSILENT Power Factory. The results of the study shown that the identified problems were real, and it needs to be addressed before damages can be done to the equipment. The proposed solution to the network was to double feed the network. Double feeding is a solution that proposed an extra connection to the grid in the farthest node in the distribution network. The proposed solution has been tested and promising results were found. Overall the study has been helpful to test the capability of a distribution network to handle a various degree of PV production level and how double feeding affected the power quality of the network. More research in the network is needed, especially with a real distribution network involved as a real network will behave differently compared to the simulated network
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Probabilistic estimation of hosting capacity and operating reserve including optimisation of PV installation capacity
Get PDFIn recent times the need to deploy additional sustainable generation means has become more apparent due to the ever-changing landscape of the global energy generation sector. Australia’s changing consumer needs means new technologies like renewable generation sources such as solar PV systems have increased in popularity over time, though their full capability has not yet been met. Though their intermittent generation is cause for concern in maintaining a stable and quality power supply. This thesis aims to address the issues by developing a probabilistic methodology for the day ahead estimate of the maximum hosting limits capacity and minimum operating reserve requirements of a microgrid containing high levels of PV penetration.
Before the commencement and development of the project, a wide range of methods from literature were analysed regarding microgrids and their use in this project. The comprehensive range of concepts of microgrids and their distributed generation were divulged and incorporated into the project methodology. To understand how to provide the probabilistic estimate of the maximum hosting capacity, three previously methods in literature were analysed, each providing more technically advanced approaches than the last. The same research approach was used to understand the methodology of developing a probabilistic estimate of the operating reserve. These methods range in methodology, from the Monte Carlo simulation method to advanced artificial neural networks.
To provide the day ahead estimates, an artificial neural network is developed to generate the network parameter forecasts required, providing with it, a probabilistic range of input to a network model. The maximum hosting capacity limit will ensure the amount of renewable generation expected will not exceed the performance indexes required for, voltage level, line loading limits and generator reverse power flow. The minimum operating reserve will provide an estimate of the reserve generation required if there were to be a sudden drop in the renewable energy supply. The estimates are created by modelling the IEEE 13-bus network in PowerFactory containing high levels of renewable generation. The programming functionality in this package has been utilised to automate the immense simulation, calculation and data collection processes required on a case by case basis. Statistical analysis is performed to define the probability of these estates occurring. The probabilities of these estimates will help network operators in making decisions for the control of the microgrid. Adding to these estimates were the PV generation capacity optimisations to increase the maximum hosting capacity limit.
Several test cases were created to analyse the performance of the modelling automation developed. Each of these cases created a different insight into the estimation and optimisation cases and their interaction with the performance indexes. The probabilistic estimations derived produced a normal distribution of values for each of the cases tested. Probability statistics are applied to provide the probability of such estimates occurring for the next day's operation. The optimisation successfully provided the maximised PV generation, setting a maximum hosting capacity within the performance index limits.
The methodology developed was successful in providing the probabilistic estimation required and optimising the PV installed capacity. This method offered the use of advanced technology, such as artificial neural networks, to provide more reliable predictions into the network operation
Customer-Side Voltage Regulation to Mitigate PV-induced Power Quality Problems in Radial Distribution Networks
Get PDFThe objective of this thesis is to illustrate the effectiveness of customer-side voltage regulation in unbalanced distribution networks, under increasing levels of distributed generation, with the overarching aim of reducing voltage magnitude and voltage imbalance violations. The voltage regulators will be installed between the point of common coupling and the customer point of access. This thesis focusses on a static timeseries load flow study that has been developed using Python 3.6.
Load flow simulations have been carried out at PV penetrations levels from 30 to 100 per cent, utilising three different loads models––constant power, constant impedance and an equal impedance-power ratio. An algorithm has been developed for selecting the location of the voltage regulators, which uses the performance of the network in terms of voltage magnitude and voltage imbalance. The test network is based on a real four-wire multipleearthed neutral distribution network in Perth, Western Australia. Real and reactive power readings from customer meters have been used. The voltage regulator model is constructed around an autotransformer regulator with 32 steps and an effective adjustment range of ±10%.
The proposed voltage regulation methodology in this thesis is effective in addressing the problems of voltage magnitude violations and to a lesser extent, voltage imbalance, in the presence of high PV penetration. However, the benefits this solution offers in terms of voltage violation reduction, loss reduction and autonomous operation, are not enough to overcome the current cost of these devices. The existing on-load tap changer solution modelled in this thesis for comparison, is shown to deliver better technical outcomes in terms of network performance, for less cost
DC microgrid simulation and control
Get PDFHowever, one of the primary challenges in the microgrid is controlling power electronic devices when it is coordinated with the utility grid. The control system in the microgrid has the main objectives, to ensure supply power to the critical loads, to connect and disconnect the load in case of any fault occurring in the microgrid. This thesis investigates different types of strategies used to control and manage a microgrid; also, the report considers inverter control in islanded mode.
This thesis explores the ideas for controlling a microgrid in terms of voltage control in both centralized and decentralized configurations. In more detail, simulations were carried out on two control strategies; inverter control, and frequency control. The inverter control method having the ability to bring the stable and efficient electricity to microgrid system has attracted much consideration in recent years. The droop controller had the capability to autonomously perform equal power sharing and maintain stability in islanded mode of operation.
There are many existing dc microgrid around the world. Kythnos Island microgrid is one of those existing microgrid, which can supply 12 houses within the island by using the inverter controller, as the utility grid is located far away from the microgrid. However, this island is either ac or dc loads, so some inverters and converters will be involved in the network.
The investigation used MATLAB /SIMULINK to simulate the microgrid network. Which done by implementing the controller in the both ac and dc load. The performance measures such as power sharing accuracy between the microgrid and diesel generator will be obtained. The diesel generators used as a backup in the case of any fault occur in the microgrid. The network simulations at different dc and ac loads will be simulating by using Simulink. This then used to calculate the efficiency of the whole network through the Simulink. Then how efficiency is can be used to upgrade the network as future scope.
Active and reactive power in the droop control has been commonly reported on and has been shown to work over a series of the condition of the network. The PQ inverter improves the performance of microgrid in islanded mode; however, the result demonstrates that the inverter controller performed well in the simulation of the Kythnos microgrid network. The efficiency of the LVDC indicates that inverter controller with the ac load performance higher efficiency compared to the dc loads
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Overview of IEC Recommendations for renewable energy and hybrid systems for rural electrification
Get PDFThe International Electrotechnical Commission (IEC) is a universal company having a major mission to arrange International standards. IEC TS 62257 introduced herein is one of those series. It concerns about rural electrification which is further away from the national main power line. It is very expensive to get a few single users to utilise a grid to meet cost-effective. Therefore the stand-alone electrical systems are taken into account to serve better situations. In these days, rural electrification is played one of the important strategies to maximise comfort to those people in rural area as well as rural economic expansion.
This thesis focuses on overview of IEC TS 62257. The project purpose concerns to five significant points. Firstly, to investigate and enable the choice of renewable energy based electrification systems to meet the requirements of customers in the field of decentralised rural electrification project. Secondly, to provide a technical specification for renewable energy and hybrid systems. Thirdly, to evaluate the minimum sufficient requirements, relevant to the field of application that is: renewable energy and hybrid off-grid systems corresponding to the high standard safety. Fourthly, to review the methodology in the standard IEC TS 62257 to achieve the best technical and economic conditions for acceptance, operation, maintenance and replacement of equipment and complete system life cycle. Lastly, to learn about the combination of diesel generator system and solar energy during the project.
To attain an achievement of the five purposes as above mentioned, Rottnest Island case study was taken as an example of rural or remote Electrification in order to compare it with IEC TS 62257 series in term of similarity and difference between them. Although this project is completed, Rottnest power electrification is still a lot more to discover.
Regarding to the most efficiency of the rural power project, the selection in which part of IEC TS 62257 should be taken to an appropriate consideration
- …
