This thesis describes the implementation of the Flexible AC Transmission Systems (FACTS) devices to develop a market-based approach to the problem of transmission congestion management in a Balancing Market. The causes, remedies and pricing methods of transmission congestion are briefly reviewed. Balancing Market exists in markets in which most of the trading is done via decentralized bilateral contracts. In these markets only final adjustments necessary to ensure secure system operation is carried out at a centralized Balancing Market. Each market player can participate in the Balancing Market by submitting offers and bids to increase and decrease its initially submitted active generation output. In this research a method is proposed to reduce costs associated with congestion re-dispatch in a Balancing Market by optimal placement of FACTS devices, and in particular Thyristor Controlled Phase Shifter Transformers (TCPST). The proposed technique is applicable to both Mixed Integer Linear Programming (MILP) and Mixed Integer Non-Linear Programming (MINLP). In the MILP a power system network is represented by a simplified DC power flow under a MILP structure and the Market participants' offers and bids are also represented by linear models. Results show that applications of FACTS devices can significantly reduce costs of congestion re-dispatch. The application of the method based on the MINLP creates a nonlinear and non-convex AC OPF problem that might be trapped in local sub-optima solutions. The reliability of the solution that determines the optimal placement of FACTS devices is an important issue and is carried out by investigation of alternative solvers. The behavior of the MINLP solvers is presented and finally the best solvers for this particular optimization problem are introduced. The application of DC OPF is very common in industry. The accuracy of the DC OPF results is investigated and a comparison between the DC and AC OPF is presented.

An Integrated Power System (IPS) with a DC Zonal Electrical Distribution System (DC ZEDS) is a strong candidate for the next generation submarine and surface ship. To study the implementation of an IPS with DC ZEDS, members of the Energy Sources Analysis Consortium (ESAC) are currently constructing a reduced-scale laboratory. One fundamental component of DC ZEDS is the Ships Service Converter Module (SSCM), commonly known as a buck DC-DC converter. This thesis documents the design, simulation, construction and testing of a 500V/400V, 8kW resonant soft-switched DC-DC converter. In theory, resonant converters will operate more efficiently and generate less Electromagnetic Interference (EMI) when compared to a standard hard-switched converter. In this thesis, the resonant converter is tested and compared to a hard-switched DC-DC converter that was designed for ESAC's reduced-scaled IPS. The results verify that the resonant DC-DC converter realizes significant efficiency and EMI generation improvements over the hard-switched converter at the cost of a more complex control system and power section. / US Navy (USN) author

Approved for public release; distribution is unlimited / This thesis formulates and solves a mixed-integer program to plan the recovery of an electrical power transmission grid that has been damaged by a natural disaster or terrorist attack. The damage can be extensive and recovery can take weeks or months. An efficient recovery plan that maximizes the utilization of repair resources can help ensure swift restoration of services. The network recovery-planning model is implemented in GAMS (General Algebraic Modeling System) and uses CPLEX as the solver. An electrical grid based on IEEE's 300-bus transmission network is used for testing. To simulate varying degrees of damage to the network, we choose up to 20% of the grid's lines, buses and transformers to be placed out of service. Based on the availability of repair resources, the repair-time horizon and penalties for unserved demand, the model produces a repair schedule that minimizes the cost of power shed. We demonstrate that for a network with up to 8% of its components damaged, the model can produce an optimal recovery plan within 20 minutes on a 2 GHz personal computer. For our largest test-case with 20% of network components damaged, the recovery plan is within 7% of optimal after 1 hour of solver time. / Outstanding Thesis

M.Ing. / With the increased use of nonlinear loads such as variable speed motor drives and rectifiers, the voltages and currents on the power system grid are no longer sinusoidal. These non-sinusoidal waveforms cannot be analyzed by conventional power theories and the usual recourse is to decompose the nonlinear waveform into a set of harmonics. Harmonic voltage and current components are detrimental to the power system and may cause additional losses, or premature failure of equipment, and as such they have a definite influence on the quality of supply. This thesis shows the limitations and potential pitfalls of harmonic decomposition and other power theories, and examines various methods used for identifying, quantifying and modelling nonlinear loads. The aim of the thesis is to evaluate methods for attaching a specific disturbance or non-linearity on the voltage waveform to a specific load connected at the point of common coupling. The power theories examined include the total complex power, the IEEE working group definitions of apparent power, true power factor and harmonic adjusted power factor. Some new techniques for estimating the degree to which a load is disturbing the voltage at the point of common coupling is introduced, including the calculation of correlation indices, and the the use of wavelets.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The power system frequency must be kept as close as possible to the nominal value. This is due to the inherent design of electrical equipment to operate efficiently at the nominal frequency. Frequency regulation in an interconnected power system is the duty of all members of the interconnection. However, in the Eskom-ZESA interconnected power system Eskom engineers ignore the contribution of the ZESA system to primary frequency control. This is mainly due to the prevalent assumption that the ZESA control area is small relative to the Eskom control area and its contribution to primary frequency control of the interconnected power system is negligible. This document presents a project that examines the validity of this assumption via determination of the contribution of the ZESA system to the interconnected power system’s primary frequency control. The interconnected power systems background was studied to understand the theory behind the operation of two or more interconnected power systems. System frequency disturbances deemed to be a good representation of the Eskom-ZESA interconnected power system’s performance were selected and analysed to validate the current assumption. The results show that there is a significant support from ZESA during a system frequency disturbance. This proves that the existing assumption is not valid anymore. Furthermore; the generator model that mimics the Eskom-ZESA tie-line governing behaviour was developed. Two different types of governor models were employed; firstly the IEEEG1 governor was tuned to control generator output to match the tie-line performance and then the TGOV5 governor model was used. The IEEEG1 governor model is a simplified governor representation; as a result, it is not easy to tune the parameters to match tie-line response. However, the performance is acceptable and it can be used to represent the tieline governor response. The TGOV5 governor model is very complex as discussed in section 4.2. The model includes boiler dynamics, and this improves performance such that it is possible to tune the parameters to follow the tie-line performance as close as necessary. / GR2016

Bi, Suzhi. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 113-119). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

本论文开发出了一个全新的理论和算法框架用於无线网络的分布式功率控制。我们提出两种快速分布式功率控制算法，并对此作了深入的研究。 此种算法相当普适，比如适用于目前热门的LTE和认知无线电网络。 它在解的最优性以及收敛速度等方面击败了著名的高通公司的"荷载溢出型分布式功率控制算法" (收录于重要论文[HandeRanganChiangWu08] )以及"分布式加权比例型信干噪比均衡算法" (收录于重要论文[TanChiangSrikant 11)。 / 作为一个重要而富有挑战性的研究课题，通过分布式功率控制达至无线网络效用的最大化一直受到业界的普遍关注。 这方面的研究通常把问题表述为一个最优化问题，即在某些功率约束条件下，优化整体系统的效用函数。 (其中，系统的效用函数通常是各无线收发链路的信干噪比的增函数。 )此问题已经有了不错的集中式解决方案，但成本更低廉、更易于布置、更为实用的分布式解决方案则欠奉，尤其是经严格证明可行的分布式解决方案。 这是因为分布式算法一般只适用于相对简单或者有特殊结构的优化问题。 而无线设备之间的相互干扰和各自信号功率之间的复杂关系使得分布式求解极其困难。 在算法设计上，很小的疏漏就可能导致解决方案无效或者不收敛。 例如，尽管论文[HandeRanganChiangWu08] 和[TanChiangSrikant 11] 都声称各自的分布式算法提供了问题的最优解，但我们通过大量的仿真实验以及理论研究发现并非如此。 我们发现"荷载溢出型分布式功率控制算法"时常要么无法收敛，要么收敛得极其慢。而"分布式加权比例型信干噪比均衡算法"则经常在几次迭代之後就已经发散。 / 我们开发出了全新的分析和算法框架，并将其推广到适用于一般线性功率约束的情况。(前述论文的分析框架是基于某些非常特殊的线性功率约束。)在此基础上，我们逐一找出了前述算法中的错漏之处，并设计出我们的分布式梯度投影功率控制算法，以及与之相匹配的步长规则。 我们严格证明了该步长规则的有效性和算法的收敛性、最优性，并给出了算法复杂度的分析。(相较之下， [HandeRanganChiangWu08] 在算法收敛性证明上语焉不详，在其它方面则付之阙如;而[TanChiangSrikant 11] 的算法收敛性证明存在明显错误，在其它方面同样付之阙如。 )在某些情况下，我们的算法可以进一步提速并提升运行性能。 大量的仿真实验证实我们的算法在解的最优性和运行速度两方面都较前述算法优越。在某些情况下，我们算法的收敛速度上百倍快于前述算法。 / 总而言之，本论文成功解决了重要的效用优化问题并取得比前述论文更好的结果。它开发出全新的理论和算法框架，完全解决了步长规则和收敛性、最优性这些难题。展望未来，我们相信，本论文为快速功率控制在无线和移动解决方案中的应用打下了坚实的理论基础。 我们期待该理论框架能够提供更多問題的解決方案。 / This thesis develops a new theoretical and algorithmic framework for practical distributed power control in wireless networks. It proposes and investigates fast optimal distributed power control algorithms applicable to LTE as well as cognitive radio. The proposed algorithms beat the well-known Qualcomm's load-spillage distributed power control algorithm in [HandeRan-ganChiangWu08] and the distributed weighted proportional SINR algorithm in [TanChiangSrikant11] in terms of both the optimality of the solution and the convergence speed. / Wireless network utility maximization via distributed power control is a classical and challenging issue that has attracted much research attention. The problem is often formulated as a system utility optimization problem under some transmit power constraints, where the system utility function is typically an increasing function of link signal-to-interference-plus-noise-ratio (SINR). This problem is complicated by the fact that these wireless devices may interfere with each other. In particular, the wireless devices are affected by each other's transmit power, and the transmit powers and interferences experienced by the devices are interwoven in a complex manner. / Despite that, there have been good centralized algorithms for solving the problem. "Decentralized" solutions, on the other hand, are a different story. In practice, decentralized algorithms in which the devices interact with each other in a loosely coupled manner to improve the network utility, are easier to deploy than centralized algorithms. However, the design of workable (and provably workable in the mathematical sense) solution is very challenging. Small neglects can lead to solutions that are invalid or non-convergent. For example, although both papers [HandeRanganChiangWu08] and [TanChiangSrikant11] claim their distributed algorithms to be optimal, we discover some experimental evidence suggesting that certain parts of these algorithms are not quite right. Oftentimes, the former fails to converge or converges extremely slowly, while the latter could diverge in the first few iterations. / To fix these glitches and to broaden the scope of the problem, we develop a new analytical and algorithmic framework with a more general formulation. With this framework, we can identify the sources of the defects and shortcomings of prior algorithms. We further construct an optimal distributed (sub)gradient projection algorithm with provably valid step size rules. Rigorous convergence proof and complexity analysis for our algorithm are given (note: convergence proof and complexity analysis were missing in [HandeRanganChiangWu08] and incorrect in [TanChiangSrikant11]). In some scenarios, our algorithm can be further accelerated to yield even better performance. Extensive simulation experiments confirm that our algorithms always outperform the prior algorithms, in terms of both optimality and efficiency. Specifically, simulation demonstrates at least 100 times faster convergence than the prior algorithms under certain scenarios. / In summary, this thesis solves the important SINR-based utility maximization problem and achieves significantly better results than existing work. It develops a new theoretical an dalgorithmic framework which completely addresses the difficult convergence and step-size issues. Going forward, we believe the foundation established in this work will open doors to other fast distributed wireless and mobile solutions to problems beyond the power control problem addressed here. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhang, Jialiang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 83-87). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Thesis Organization --- p.6 / Chapter 1.3 --- Notations --- p.7 / Chapter 2 --- System Model and Problem Formulation --- p.8 / Chapter 2.1 --- System Model --- p.8 / Chapter 2.2 --- Nonnegative Linear Power Constraints --- p.9 / Chapter 2.3 --- Network Utility --- p.10 / Chapter 2.4 --- Problem Formulation --- p.11 / Chapter 2.5 --- Characterization of T[subscript c] --- p.13 / Chapter 2.6 --- Multiple Constraints --- p.16 / Chapter 3 --- Nice Properties of SINR Constraints --- p.18 / Chapter 3.1 --- Convexity, Differentiability and Monotonicity --- p.19 / Chapter 3.2 --- Fast Distributed Gradient Computation --- p.20 / Chapter 3.2.1 --- Distributed SINR-Driven Single-Constrained Power Control --- p.21 / Chapter 3.2.2 --- Network Duality --- p.23 / Chapter 3.3 --- The Case of Multiple Constraints --- p.27 / Chapter 4 --- Network Utility Maximization in Log-SINR Domain --- p.32 / Chapter 4.1 --- Single Active Constraint and Ascent Directions --- p.34 / Chapter 4.2 --- Multiple Constraints and Subgradient Projection --- p.39 / Chapter 4.3 --- Unconstrained Equivalence and Complexity results of M = 1 --- p.46 / Chapter 4.4 --- Simulation Experiments --- p.52 / Chapter 4.4.1 --- Simulation Settings --- p.52 / Chapter 4.4.2 --- Negative results of algorithm 6 in [7] --- p.54 / Chapter 4.4.3 --- Negative results of Qualcomm’s load-spillage algorithm in [25] --- p.56 / Chapter 4.4.4 --- More results of our algorithms --- p.62 / Chapter 5 --- Related Work --- p.64 / Chapter 6 --- Conclusion --- p.68 / Chapter 7 --- Appendix --- p.72

This thesis presents investigations into the effect of modern wind farms on grid side short circuits using extensive real time digital simulation. Particular reference is made to adaptive autoreclosing algorithms using artificial neural networks. A section of 132kV transmission grid in Scotland, including DFIG wind farms, is modelled on a real time digital simulator. An algorithm is then developed and tested using this model to show that this autoreclosing technique is feasible in systems with high penetration of wind generation. Although based on an existing technique, an important innovation is the use of two neural networks for the separate tasks of arc presence and extinction. The thesis also describes a low-cost, real time, relay development platform.

There is a drive to transform the electricity industry in the UK from one based largely on fossil fuels to one based on low or zero carbon sources. The challenge of this transition, enabling a secure and sustainable electricity industry at an acceptable cost to consumers, has been dubbed the Energy Trilemma. Grid-connected electrical energy storage presents a potential solution to this challenge. However, the benefits of storage are split across different sectors of the electricity industry and there are a number of regulatory barriers preventing access to revenue streams. One accessible revenue stream is energy trading or price arbitrage. In current market conditions, arbitrage cannot provide sufficient revenue for electricity storage to cover its capital costs; however, some studies have suggested that with increased penetration of intermittent renewable power, electricity price volatility will increase enabling storage to become commercially viable through price arbitrage alone. This thesis examines the hypothesis that: Increased wind penetration leads to increased commercial opportunities for energy storage through price arbitrage. A linear programme is used to define the optimum operating strategy for a storage device, subject to the constraints of maximum storage capacity, charging and discharging rates, conversion efficiency and self-discharge. Initially, historic electricity prices from the British electricity market are used to investigate the value of storage with a low penetration of intermittent wind power. The results show that revenue is dependent on storage characteristics, with the performance of different technologies varying substantially. Furthermore, revenue is highly dependent on changes in market structure and fuel price variations from one year to the next. The thesis describes the development of a fundamental electricity price model based on the stacked merit order dispatch of thermal generation bidding to produce electricity in a competitive market centred around marginal generation costs. For peaking plant, an exponential uplift in price is applied to represent scarcity of supply. The implications of increasing wind power output are examined using projections of the location and capacity of future wind farms and spatially distributed hind cast wind speed data generated from a mesoscale atmospheric model. The analysis highlights that despite increased value being placed on storage in an energy system with a high penetration of wind power, opportunities for arbitrage are, in fact, reduced. This is a result of an oversupply of electricity on windy days suppressing peak electricity prices and reducing the daily price spread, which arbitrage exploits.

Submitted by Sandro Camargo (sandro.camargo@unipampa.edu.br) on 2015-05-09T18:28:47Z No. of bitstreams: 1 107110006.pdf: 2090462 bytes, checksum: 5fecbc3cc993bd7ac1637e41b7b2be41 (MD5) / Made available in DSpace on 2015-05-09T18:28:47Z (GMT). No. of bitstreams: 1 107110006.pdf: 2090462 bytes, checksum: 5fecbc3cc993bd7ac1637e41b7b2be41 (MD5) Previous issue date: 2012-10-19 / Com a total dependência pela energia elétrica em todos os setores da sociedade e a consequente regulamentação, é necessário que as concessionárias se preocupem em manter a continuidade do seu fornecimento, além de atender aos padrões que remetem à qualidade. A continuidade do fornecimento de energia elétrica é algo fundamental tanto para os consumidores quanto para a concessionária, a qual deixa de vender energia elétrica e ainda pode ser penalizada por interrupções muito longas ou em áreas críticas (hospitais ou indústrias, por exemplo). Como nem sempre é possível manter a continuidade do fornecimento devido a diversos fatores, sendo os defeitos permanentes os mais críticos, as empresas concessionárias são levadas a procurar novas metodologias e tecnologias para diminuir o tempo que o fornecimento de energia elétrica é interrompido. Nesse trabalho é descrita uma metodologia para o restabelecimento da energia em redes de distribuição de maneira automática. Essa metodologia se baseia no uso de tecnologias de comunicação e na automação dos equipamentos de manobras das redes. Com isso é possível obter os dados do estado da rede em tempo real, e é possível enviar os comandos para tais equipamentos de forma direta, sem a necessidade de intervenção humana. A metodologia aqui apresentada tem como objetivo detectar a localização de um defeito na rede através de leituras dos estados dos equipamentos, e então procurar as melhores manobras que restabeleçam o fornecimento ao máximo de consumidores sem que isso coloque todo sistema de distribuição, ou mesmo parte dele, em sobrecarga. Também é considerado que a rede pode ter sofrido alterações em equipamentos não automatizados (chaves manuais), e que as características de carga mudam no decorrer do tempo. Assim, a topologia deve ser atualizada antes de executar simulações e que os dados para tais simulações devem prever o comportamento da carga para o tempo que a contingência possa durar. Como teste da metodologia, foram executadas simulações em dados de redes reais de distribuição com diferentes topologias e diferentes cenários de defeitos. Os resultados obtidos foram satisfatórios na medida que tais soluções de restabelecimento eram viáveis em termos de carregamento da rede e foram calculadas em um curto espaço de tempo (poucos segundos). Essa agilidade traz vantagens tanto para os clientes quanto para a própria concessionária. / With the total dependency for electric power in all society sectors and the following regumen-tation, is necessary that the utilities worry in maintaining the continuity of power supply, in addition to meeting the standards that refer to quality. The continuity of power supply is fun- damental both for consumers and for the utility, which stops selling electricity and can still be penalized for too long interruptions or in critical areas (hospitals or industries, for example). As it is not allways possible to maintain the continuity of power supply due several factors, being the most critical the permanets defects, the utilities are driven to seek new methods and tecnologies to reduce the time that power supply is interrupted. In this work we describe a methodology for automatic restoration in power grids. This methodology is based on the use of communication technologies and automation equipment maneuvers networks. With this is possible to get the data status from the grid in real time, and also can send commands to these devices directly, without the need for human intervention. The methodology presented here tries to detect the location of a fault on the grid, through readings of the equipments status, and then search for the best maneuvers to restores supply to maximum consumers without putting the entire distribution system, or portion thereof, in overload . It is also considered that the grid may have changed in non-automated equipment (manual keys), and that the load characteristics change over time. Thus, the topology must be updated before running simulations and data for such simulations should predict the behavior of the load for time that can last contingency. As a test of the methodology, simulations were performed on real power grids data with different topologies and different scenarios defects. The results were satisfactory as such restoration solutions were viable in terms of network loading and were calculated in a short time (few seconds). This agility has benefits both for customers and for the own utility.