Thesis (PhD (Electrical Engineering))--Cape Peninsula University of Technology, 2018. / Electrical energy can be easily used and converted to other forms of energy for various applications. Technological advancement increases the dependency on electricity to a great extent. Various internal and external factors are responsible for the bad quality of power in power systems. The performance of the system is greatly affected by the presence of harmonics, as well as voltage and frequency variations, which leads to the malfunctioning of the device and decline of power quality and supply at load side. The reactive power compensation is carried out for better power quality. The literature survey is done to find the best and efficient scheme for reactive power compensation and mitigation of various power quality problems. The devices which are used to measure various power quality factors are discussed. Various mitigating schemes are surveyed in order to compensate reactive power and to improve the power quality at the distribution end. The integration of the most widely used renewable energy, wind energy in the distribution system creates technical issues like stability of the grid, harmonic distortion, voltage regulation, active and reactive power compensation etc. which are restricted to IEC and IEEE standards. One of the topics this thesis addresses is regulation in the reactive power generated along with voltage regulation by using an effective power electronics device known as a STATCOM. The main power quality factors like overvoltage and voltage flickers are mitigated by establishing STATCOMs in small wind farms. The wind farms are equipped with three wind turbines. These three wind turbines found in the wind farm can be operated together or one after another with an introduced delay. A glitch in even a little piece of a power grid can result in loss of efficiency, income and at times even life. In this manner, it is basic to outline a system which can distinguish the faults of the power system and take a faster response to recover it back to required reactive power. Two devices STATCOM and D-STATCOM are used for this purpose in this thesis. The D-STATCOM circuit and operating principle are also discussed in thesis. Different topologies of D-STATCOM discussed with their benefits and shortcomings. The voltage, current and hybrid technologies of D-STATCOM are also discussed.

É notável que o Sistema Elétrico de Potência (SEP) está constantemente exposto a adversidades ocasionadas por forças da natureza ou desgastes naturais de seus componentes. A localização com certa exatidão de uma falta no Sistema de Transmissão de Energia Elétrica (STEE), ocasionada por uma destas adversidades, contribui para a confiabilidade e segurança da operação do SEP. Neste contexto, este trabalho apresenta um método computacional de Localização de Faltas (LDF), desenvolvido em ambiente MATLAB®, baseado na Impedância Aparente (IA), utilizando dados de apenas um terminal, sendo o equacionamento desenvolvido em componentes simétricas. Este método tem como dados de entrada as componentes fundamentais de tensão e corrente do terminal local e a Potência de Curto Circuito (SCC) do sistema equivalente conectado ao terminal remoto. Para validar o método proposto foram realizadas diversas simulações para todos os tipos de faltas shunt, contemplando inúmeras condições destas, utilizando para isso, o programa computacional ATP-EMTP, alimentado com dados de parâmetros reais de um sistema de transmissão. Objetivando analisar a eficiência deste método, realizou-se a comparação de seus resultados com os resultados obtidos por um método estado-da-arte. A partir de análises e comparações, os resultados alcançados pertencentes ao método de LDF proposto, apresentam-se promissores para a LDF em sistemas de transmissão. / Electric Power Systems (EPS) are constantly exposed to adversities caused by forces of nature and components lifetime. The precise fault location in the Transmission System (TEPS), caused by these adversities, contributes to the reliability and safety the operation of the EPS. In this context, this work presents a computational method for fault location (FL), developed in MATLAB ® environment, based on the Apparent Impedance (AI) of the transmission line. The proposed method uses only one terminal data and is developed in symmetrical components equations. This method has as input data the fundamental components of voltage and current of the local terminal and the short circuit power (SCP) of the equivalent system connected to the remote terminal. The proposed method is validated through several simulations for all fault types, covering many fault conditions, making use of the software ATP-EMTP, fed with data from the actual parameters of a real life transmission system. Aiming to analyze the efficiency of this method, a comparison was made against the an state-of-the-art method. From analysis and comparison of the results obtained, is observed that the proposed scheme is capable to obtain precise fault location estimations and presents as promising method for the FL in transmission systems.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2013 / The demand for electrical energy has kept on increasing, thus causing power systems to be more complex and bringing the challenging problems of electrical energy generation, transmission, stability, as well as storage to be examined more thoroughly. With the advent of high-speed computation and the desire to analyze increasingly complex behaviour in power systems, simulation techniques are gaining importance and prevalence. Nevertheless, while simulations of large, interconnected complex power systems are feasible, they remain time-consuming. Moreover, the models and parameters used in simulations are uncertain, due to measurement uncertainty, the need to represent a complex behaviour with low-order models, and the inherent changing nature of the power system. This research explores the use of a model reduction technique and the applications of a Real-Time Digital Simulator (RTDS) to reduce the uncertainty in large-scale complex power system models. The main goal of the research is to develop a reduced order model and to investigate the applications of the RTDS simulator in reduction of large, interconnected power systems models. The first stage of the study is to build and simulate the full model of the power system using the DigSILENT and RTDS simulators. The second phase is to apply model reduction technique to the full model and to determine the parameters in the reduced-order model as well as how the process of reduction increases this model uncertainty. In the third phase the results of the model reduction technique are compared based on the results of the original model - IEEE standard benchmark models has been used. The RTDS was used for comparative purposes. The thesis investigations use a particular model reduction technique as Coherency based Method. Though the method ideas are applicable more generally, a concrete demonstration of its principles is instructive and necessary. Further, while this particular technique is not relevant to every system, it does apply to a broad class of systems and illustrates the salient features of the proposed methodology. The results of the thesis can be used in the development of reduced models of complex power systems, simulation in real-time during power system operation, education at universities, and research. Keywords: IEEE benchmark models, reduced models, Coherency based Method, DigSILENT, RTDS, model uncertainty, power system stability

É notável que o Sistema Elétrico de Potência (SEP) está constantemente exposto a adversidades ocasionadas por forças da natureza ou desgastes naturais de seus componentes. A localização com certa exatidão de uma falta no Sistema de Transmissão de Energia Elétrica (STEE), ocasionada por uma destas adversidades, contribui para a confiabilidade e segurança da operação do SEP. Neste contexto, este trabalho apresenta um método computacional de Localização de Faltas (LDF), desenvolvido em ambiente MATLAB®, baseado na Impedância Aparente (IA), utilizando dados de apenas um terminal, sendo o equacionamento desenvolvido em componentes simétricas. Este método tem como dados de entrada as componentes fundamentais de tensão e corrente do terminal local e a Potência de Curto Circuito (SCC) do sistema equivalente conectado ao terminal remoto. Para validar o método proposto foram realizadas diversas simulações para todos os tipos de faltas shunt, contemplando inúmeras condições destas, utilizando para isso, o programa computacional ATP-EMTP, alimentado com dados de parâmetros reais de um sistema de transmissão. Objetivando analisar a eficiência deste método, realizou-se a comparação de seus resultados com os resultados obtidos por um método estado-da-arte. A partir de análises e comparações, os resultados alcançados pertencentes ao método de LDF proposto, apresentam-se promissores para a LDF em sistemas de transmissão. / Electric Power Systems (EPS) are constantly exposed to adversities caused by forces of nature and components lifetime. The precise fault location in the Transmission System (TEPS), caused by these adversities, contributes to the reliability and safety the operation of the EPS. In this context, this work presents a computational method for fault location (FL), developed in MATLAB ® environment, based on the Apparent Impedance (AI) of the transmission line. The proposed method uses only one terminal data and is developed in symmetrical components equations. This method has as input data the fundamental components of voltage and current of the local terminal and the short circuit power (SCP) of the equivalent system connected to the remote terminal. The proposed method is validated through several simulations for all fault types, covering many fault conditions, making use of the software ATP-EMTP, fed with data from the actual parameters of a real life transmission system. Aiming to analyze the efficiency of this method, a comparison was made against the an state-of-the-art method. From analysis and comparison of the results obtained, is observed that the proposed scheme is capable to obtain precise fault location estimations and presents as promising method for the FL in transmission systems.

This dissertation is a systematic study of the 22kV Nelson Mandela Bay Municipality (NMBM) electricity power distribution network reliability evaluation and improvements to be applied. Reliability evaluation of electric power systems has traditionally been an integral part of planning and operation. Changes in the electricity utility, coupled with aging electrical apparatus, create a need for more realistic techniques for power system reliability modelling. This work presents a reliability evaluation technique that combines set literature and evaluation criteria. In analysing system reliability, this research takes into account the reasons for many outages and voltage dips and seeks to find mitigating approaches that are financially justified. The study analyses the power system in terms of the methodology developed, using power system reliability techniques, power quality evaluation, protection analyses and evaluating the network against maintenance interventions and programs, manpower availability and weather conditions contributing to the outages. In evaluating the power system various techniques are used to determine if the power network operates within the NRS standards, namely, reliability calculations, testing of protection equipment, interrogation of power quality instruments and modeling the network on Digsilent. This study will look at all the important factors influencing power system reliability, analysing the network in terms of the methodology and recommend improvements.

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Studies regarding the development of a new hydropower plant exploiting the water resources offered by the upper Tinguiririca river, located about 150 km south-east of the capital Santiago in Chile, has been done by Pacific Hydro Ltd from Australia and Lahmeyer International from Germany. These studies have resulted in proposals to construct two Hydropower Stations, �La Higuera� and �Confluencia�. Both hydropower stations will have a total installed capacity of 300 MW. When setting up a new hydropower plant, it is important to foresee how the hydropower plant would affect the existing transmission grid in different situations during operation as well as how events in the grid may affect the La Higuera and/or Confluencia hydropower stations. In this report three kind of analysis are highlighted, which are static analysis, large signal stability and rotor angle stability. To perform these analyses a simulation tool named DigSilent is used. DigSilent is used to perform these analyses in a simulated network of the studied transmission system. These two hydropower stations as shown in the results will improve the existing transmission system by enhancing the stability margins in the presence of a fault. When performing the simulation of the existing transmission system with the newly installed hydropower plant we could see that it had a poor damping after a disturbance; this might be due to the large distance between production plants and the existing loads. This phenomenon can be alleviated if a power system stabilizer (PSS) is integrated in the hydropower plant. The final conclusion is that the integration of the two hydropower plants will improve the existing transmission system in Chile.

This paper investigates the various parameters that effect voltage stability in sub-transmission power networks. The paper first looks at contributions from equipment: generators, transmission lines, transformers, capacitors, SVCs and STATCOMs. The paper also looks at the effects of loads on voltage stability. Power flow solutions, PV and VQ curves are covered. The study models an existing voltage problem i.e., a long, radial, 115 kV sub-transmission network that serves a 65 MW load. The network model is simulated with the following voltage instability countermeasures: adding a capacitor, adding an SVC, adding a STATCOM, tying to a neighboring transmission system, adding generation and bringing in a new 230 kV source. Then, using the WECC heavy-winter 2012 power flow base case and Siemens PTI software, VQ and PV curves are created for each solution. Finally, the curves are analyzed to determine the best solution.

As the load on the power system grows and new transmission facilities become increasingly difficult to build, the utilities must look to ways to make the most of the current transmission system. Adaptive relaying is one way to enhance the ability of the power system. On the Florida - Georgia interface an adaptive out-of-step relay is being installed. This relay determines if swings on the power system will remain stable by performing a better then real-time transient stability study. Because of the computing capacity required for a transient stability study, the study cannot be performed on the full power system. A reduced model must be used. In this thesis, various methods of obtaining reduced models for use in the relay will be explored. The models will be verified with a full system model using Electric Power Research Institute's (EPRI) Extended Transient-Midterm Stability Package (ETMSP). / Master of Science