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Masters Degrees (Electrical Engineering)

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Browsing Masters Degrees (Electrical Engineering) by Author "Carpanen, Rudiren Pillay."

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    Enhancing transient stability of power systems using a thyristor controlled series capacitor.
    (2005) Carpanen, Rudiren Pillay.; Rigby, Bruce S.
    The continuously growing demand for electric power requires transmitting larger amounts of power over long distances. An economically attractive solution to increase the power transfer through a long interconnection (up to a limit) without building new parallel circuits is to install series capacitor compensation on the transmission line. Large disturbances which constantly occur in power systems may disrupt the synchronous operation of the generators and lead to out-of-step conditions. Coordinated insertion and removal of the compensating capacitors in series with a transmission line is an approach that has been known for many years to be capable of enhancing the transient stability of power systems as well as providing additional damping to the power system oscillations. The relatively recent emergence of the thyristor controlled series capacitor (TCSC) has now made this method of transient stability enhancement practically feasible. This thesis compares a range of different strategies that have been proposed in the literature for control of series compensating reactance to enhance transient stability. Initially a simple swing-equation model of a single-generator power system, including an idealised controllable series compensator (CSC) is used to study the fundamental characteristics of the variable impedance control and its impact on transient stability. Subsequently, a detailed model of a small study system is developed, including a detailed representation of a TCSC, for more in-depth analysis. This detailed study system model is then used to compare three different transient stability control schemes for the TCSC, namely: generator speed-deviation based bang-bang control, discrete control based on an energy-function method, and nonlinear adaptive control. Time-domain results are presented to demonstrate the impact of the TCSC on first swing stability of the SMIB system with the above control schemes for various fault scenarios. The performance of each control scheme is also compared by evaluating the extent to which it extends the transient stability margin of the study system. For each of the three different TCSC control approaches considered, the results show that variable impedance control of the TCSC provides further improvement in the transient stability limits of the study system over and above the improvement that is obtained by having a fixed-impedance TCSC in the system. In the case of the bangbang and discrete control approaches, it is shown that a combination of a large steady state value of the TCSC compensation, together with a relative small range of variable TCSC reactance under transient conditions, offers. the best improvement in the transient stability limits for the studied system. The results also show that there is little difference in the extent to which the energy function method of TCSC control improves the transient stability limits over the improvement obtained using speed-deviation bang-bang control of the TCSC for the study system considered.
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    Optimization of Hybrid Renewable Electrical Energy Systems for a Port.
    (2022) Nkosi, Mbonisi Shephaerd.; Swanson, Andrew Graham.; Carpanen, Rudiren Pillay.; Ghayoor, Najafabadi Farzadna.
    The port terminals in South Africa currently face significant challenges linked to electricity constraints and security. South Africa is predominantly reliant on coal-generated electricity from the local utility for the provision of base-load electricity to power operations, and municipal distribution systems in many areas. A reduction in power in the latter part of 2015 has resulted in the curtailment of load shedding that is continuing to date, 2019. This risk is not mitigated, it is ongoing. Port terminals in South Africa rely on the throughput of the vessels to ensure that freight is moved speedily. The aspects of port operations that are generally considered in measuring port performance and efficiency are berth productivity measured in moves or volumes per ship working hour also known as across the shipping rate, cargo dwell times, crane moves per hour, ship turnaround time with less focus or no energy management. The port operations are dependent on the throughput of the operation. The energy consumed for port operations is thus independent and is difficult to control in any sort of energy management plan. Coupling this with the time of use tariffs and demand penalties, the need for an adaptable hybrid system can alleviate some stresses and contribute positively to an energy management plan. This study aims to determine that the distributed generation and storage performed by a variety of small, grid-connected referred to as distributed energy resources mitigate the energy cost issues in the port environment and reduction of Green House Gases (GHG) emissions. Distributed resources can help reduce the capacity problems to which an aging or overstressed grid is liable. The study is contributing to reducing dependence on major power plants supply and redirecting the source of supply to renewable technologies. This results in eliminating the need to erect new big power generation and deferral of new capacity. It also demonstrates that PV Solar and Wind Turbine Generation can reduce environmental impacts and gas greenhouse gas emissions. Compared to the coal power plants, distributed generators units are renewable or low emission generator-based sources. The Homer Grid simulation tool suggest distributed generation to be the solution for the port i.e., the hybrid supply that includes the integration of photovoltaic generation, wind power generation, battery energy storage system (BESS) into the electricity Municipal Grid. Both Matlab and HOMER Grid optimizations tools are used to outline different options for reducing electricity costs. These tools compare the costs and savings and uses a powerful optimization to find the system that maximizes savings. We used these tools to analyze the distributed generation grid potential, peak renewables penetration, ratio of renewable sources to total energy, and grid stability. The tools present different study cases with optimal results. The outcome shows a decrease in the cost of energy in the long term and can contribute towards the better energy management of the port.