Esta trabalho apresenta a análise e implementação de uma técnica inteligente, o algoritmo genético (AG), para implementação de unidades de medição fasoriais, denominadas PMUs (Phasor Measurement Units). A disponibilidade dos fasores em diversos pontos de um sistema elétrico de potência (SEP) é importante, tanto para monitoramento quanto para controle, proteção e estudo do sistema. Entretanto, a obtenção de tais fasores só têm sentido se os mesmos possuírem o mesmo referencial no tempo. Este referencial é conseguido através de sinais de satélites GPS (Global Positioning System) que sincronizam as PMUs instaladas nos pontos de interesse. Existe uma vasta quantidade de m´métodos que podem ser utilizados para que, de posse das formas de onda discretizadas de tensão e corrente, estime-se os fasores correspondentes e as frequências locais. Este projeto apresenta os AGs como ferramenta de estimação para a obtenção de uma PMU com todas as vantagens relativas a tais algoritmos. Além disso, uma versão do AG que utiliza menos recursos computacionais , o algoritmo genético compacto (AGc) também será estudado. Um estudo norteado pela norma internacional C37.118 compara o desempenho dos AGs com dois métodos tradicionais de medição fasorial, um baseado na transformada discreta de Fourier e outro baseado em um filtro phase-locked loop. Dados sintéticos e provenientes de simulações são utilizados para avaliar o desempenho dos algoritmos desenvolvidos. Para tirar vantagem da natureza paralela dos algoritmos genéticos, um estudo da implementação do AGc em FPGA (field programmable gate array) utilizando a linguagem VHDL e realizado a fim de estudar a implementação embarcada em PMUs. / This work presents the implementation and analysis of an intelligent technique, the genetic algorithm (GA), for the implementation of phasor measurement units (PMUs). The estimation of phasors in several spots in an electrical power system is important for the monitoring, control, protection and study of this system. However, these phasors must be in a common time reference in order to be usefull. This reference is achieved by using signals provided by the Global Positioning System (GPS) that synchronize the PMUs installed in the system. There are several techniques that can be used to estimate the phasors and local frequency using current and voltage wave signals. This project introduces the GAs as a phasor estimation tool applied to PMUs. Besides that, a version of the GA that demands less computational resources, the compact Genetic Algorithm is studied and implemented. A detailed study is performed using the international standard C37.118 as a guide comparing the GAs with two traditional techniques. The two traditional techniques are based on the DFT (Discrete Fourier transform) and a phaselocked loop filter (PLL). Synthetic and simulated data is used to evaluate the performance of the implemented algorithms. In order to take advantage of the parallel behavior of the genetic algorithms, a study of its implementation in FPGA (field programmable gate array) using the VHDL language is performed to make the genetic algorithms useful in real PMUs.

Taipower Company has already completed the installation of the Outage Management System (OMS) in all service districts. The attributes of all distribution equipments and customers have been included in the computerized mapping system. However, the phasing attributes of distribution transformers are not very accurate in the database because they are very difficult to be identified for the distribution systems. The phase information of transformers in the OMS database is often inconsistent with the actual service phase, which deteriorates the performance of distribution system analysis, planning, and operation of Taipower distribution systems. The objective of this thesis is to develop an innovative Phasor Measurement Unit (PMU) to support the phasing identification of distribution transformers in a very effective way. The proposed PMU is used to measure the low voltage signal at the secondary side of transformers to prevent the survey personnel from safety problem. With the measured phases information of distribution transformers stored in the embedded system, the attributes of transformer phases in OMS can be updated to improve the accuracy of database. For the underground distribution systems, it is very difficult to receive the 1PPS signal of GPS system for timing synchronous to support the proposed transformer phasing measurement because all transformers are located at the building basement. This thesis proposes a timing synchronous module by using the Temperature Compensated Crystal Oscillator, TCXO to maintain the timing accuracy with high precision. Before executing the phasing measurement, this module is calibrated using the GPS 1PPS signal with fuzzy control calibration algorithm. It is found that the proposed PMU module can maintain the timing synchronous with 6˚, during two hours time period which will support the transformer phasing measurement by providing the reference timing synchronous even without the GPS 1PPS signal.

This dissertation studies the performance of synchrophasor measurement obtained using substation Intelligent Electronic Devices (IEDs) and proposes new algorithms and test methodology to improve and verify their performance when used in power system applications. To improve the dynamic performance when exposed to sinusoidal waveform distortions, such as modulation, frequency drift, abrupt change in magnitude, etc, an adaptive approach for accurately estimating phasors while eliminating the effect of various transient disturbances on voltages and currents is proposed. The algorithm pre-analyzes the waveform spanning the window of observation to identify and localize the discontinuities which affect the accuracy of phasor computation. A quadratic polynomial signal model is used to improve the accuracy of phasor estimates during power oscillations. Extensive experimental results demonstrate the advantages. This algorithm can also be used as reference algorithm for testing the performance of the devices extracting synchronized phasor measurements. A novel approach for estimating the phasor parameters, namely frequency, magnitude and angle in real time based on a newly constructed recursive wavelet transform is developed. This algorithm is capable of estimating the phasor parameters in a quarter cycle of an input signal. It features fast response and achieves high accuracy over a wide range of frequency deviations. The signal sampling rate and data window size can be selected to meet desirable application requirements, such as fast response, high accuracy and low computational burden. In addition, an approach for eliminating a decaying DC component, which has significant impact on estimating phasors, is proposed using recursive wavelet transform. This dissertation develops test methodology and tools for evaluating the conformance to standard-define performance for synchrophasor measurements. An interleaving technique applied on output phasors can equivalently increase the reporting rate and can precisely depict the transient behavior of a synchrophasor unit under the step input. A reference phasor estimator is developed and implemented. Various types of Phasor Measurement Units (PMUs) and PMU-enabled IEDs (Intelligent Electronic Devices) and time synchronization options have been tested against the standards using the proposed algorithm. Test results demonstrate the effectiveness and advantages.

For decades, power engineers have used simulations to predict grid stability and voltage phase angles. Only recently have equipment been available to actually measure phase angle at points hundreds of miles away. A few of these systems are presently operating in the US by electric grids including the Electric Reliability Council of Texas (ERCOT) and California Independent System Operator (ISO). However, the systems are in their infancy and are far from being used to improve grid reliability. This thesis describes the only independent synchronized phasor network that exists in the US. Thanks to Schweitzer Engineering Laboratories (SEL), we are streaming in points from three locations plus the University of Texas at Austin (UT Austin) as of January 2009. This thesis will describe this network and grid analysis done this far. / text

This thesis proposes two novel algorithms to analyze whether the power system loses synchronism subsequent to credible contingencies. The two algorithms are based on the concept of Lyapunov exponents (LEs) and the Prony analysis respectively. The concept of LEs is a theoretically sound technique to study the system stability of nonlinear dynamic systems. The LEs measure the exponential rates of divergence or convergence of trajectories in the state space. Considering the higher computational burden associated with the convergence of the true LEs, a modified algorithm is proposed to study the transient stability of the post-fault power system. It is shown that the finite-time LEs calculated by the modified algorithm accurately predicts the said stability. If the power system is transient stable, the rotor angle trajectories of the post-fault system exponentially decay with time. The damping ratios of the dominant oscillatory modes present in these power swings provide the indication on the oscillatory stability. The improved Prony algorithm presented in the thesis can be used to identify the oscillatory stability of the power system subsequent to a contingency. It is shown that that these new algorithms can be used in two applications in power systems, online dynamic security assessment and online oscillations monitoring. The proposed algorithm for rotor angle security assessment first uses the LEs-based algorithm to identify the transient stability. The stable cases are then processed by the improved Prony algorithm. The proposed online oscillations monitoring algorithm uses an event-detection logic and a parallel filter bank before applying the improved Prony algorithm on the measured response to extract the dominant oscillatory modes and to determine their frequencies and damping ratios. The suitability of the two algorithms for the aforementioned applications is investigated using different case studies. It is shown that the computational burdens of the two algorithms are acceptable for the online applications. Furthermore, the oscillations monitoring algorithm, extracts only the dominant modes present in the input signal, extracts both low-frequency inter-area modes and sub-synchronous modes, and performs well under noisy conditions. These features make it more appropriate for wide-area monitoring of power system oscillations using synchronized measurements. / February 2016

State estimation is widely used as a tool to evaluate the real time power system prevailing conditions. State estimation algorithms could suffer divergence under stressed system conditions. This dissertation first investigates impacts of variations of load levels and topology errors on the convergence property of the commonly used weighted least square (WLS) state estimator. The influence of topology errors on the condition number of the gain matrix in the state estimator is also analyzed. The minimum singular value of gain matrix is proposed to measure the distance between the operating point and state estimation divergence. To study the impact of the load increment on the convergence property of WLS state estimator, two types of load increment are utilized: one is the load increment of all load buses, and the other is a single load increment. In addition, phasor measurement unit (PMU) measurements are applied in state estimation to verify if they could solve the divergence problem and improve state estimation accuracy. The dissertation investigates the impacts of variations of line power flow increment and topology errors on convergence property of the WLS state estimator. A simple 3-bus system and the IEEE 118-bus system are used as the test cases to verify the common rule. Furthermore, the simulation results show that adding PMU measurements could generally improve the robustness of state estimation. Two new approaches for improving the robustness of the state estimation with PMU measurements are proposed. One is the equality-constrained state estimation with PMU measurements, and the other is Hachtel's matrix state estimation with PMU measurements approach. The dissertation also proposed a new heuristic approach for optimal placement of phasor measurement units (PMUs) in power system for improving state estimation accuracy. In the problem of adding PMU measurements into the estimator, two methods are investigated. Method I is to mix PMU measurements with conventional measurements in the estimator, and method II is to add PMU measurements through a post-processing step. These two methods can achieve very similar state estimation results, but method II is a more time-efficient approach which does not modify the existing state estimation software.

abstract: On-line dynamic security assessment (DSA) analysis has been developed and applied in several power dispatching control centers. Existing applications of DSA systems are limited by the assumption of the present system operating conditions and computational speeds. To overcome these obstacles, this research developed a novel two-stage DSA system to provide periodic security prediction in real time. The major contribution of this research is to develop an open source on-line DSA system incorporated with Phasor Measurement Unit (PMU) data and forecast load. The pre-fault prediction of the system can provide more accurate assessment of the system and minimize the disadvantage of a low computational speed of time domain simulation. This Thesis describes the development of the novel two-stage on-line DSA scheme using phasor measurement and load forecasting data. The computational scheme of the new system determines the steady state stability and identifies endangerments in a small time frame near real time. The new on-line DSA system will periodically examine system status and predict system endangerments in the near future every 30 minutes. System real-time operating conditions will be determined by state estimation using phasor measurement data. The assessment of transient stability is carried out by running the time-domain simulation using a forecast working point as the initial condition. The forecast operating point is calculated by DC optimal power flow based on forecast load. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2017

The operation and control of the power system in an efficient way is important in order to keep the system secure, reliable and economical. With advancements in smart grid, several new algorithms have been developed for improved operation and control. These algorithms need to be extensively tested and validated in real time before applying to the real electric power grid. This work focuses on the development of a real time test bed for testing and validating power system control algorithms, hardware devices and cyber security vulnerability. The test bed developed utilizes several hardware components including relays, phasor measurement units, phasor data concentrator, programmable logic controllers and several software tools. Current work also integrates historian for power system monitoring and data archiving. Finally, two different power system test cases are simulated to demonstrate the applications of developed test bed. The developed test bed can also be used for power system education.

As the power industry enters the new century, powerful driving forces, uncertainties and new services and functions are compelling electric utilities to make dramatic changes in the way they communicate. Expanding network services such as real time monitoring are also driving the need for more increasing bandwidth in the communication network backbone. These needs will grow further as new remote real-time protection and control applications become more feasible and pervasive. This dissertation addresses two main issues for the future power system information infrastructure: communication network infrastructure and associated power system applications. Optical network no doubt will become the predominate network for the next generation power system communication. The rapid development of fiber optic network technology poses new challenges in the areas of topology design, network management and real time applications. Based on advanced fiber optic technologies, an all-fiber network was investigated and proposed. The study will cover the system architecture and data exchange protocol aspects. High bandwidth, robust optical network could provide great opportunities to the power system for better service and efficient operation. In the dissertation, different applications were investigated. One of the typical applications is the SCADA information accessing system. An Internet-based application for the substation automation system will be presented. VLSI (Very Large Scale Integration) technology is also used for one-line diagrams auto-generation. High transition rate and low latency optical network is especially suitable for power system real time control. In the dissertation, a new local area network based Load Shedding Controller (LSC) for isolated power system will be presented. By using PMU and fiber optic network, an AGE (Area Generation Error) based accurate wide area load shedding scheme will also be proposed. The objective is to shed the load in the limited area with minimum disturbance. / Ph. D.

The power grid is interconnected in many ways; so that when disturbances occur in a small region, their effects can be seen across large areas causing major blackouts. In order to isolate the fault, measurements taken at different times throughout the blackout need to be collected and analyzed. With each measurement device having its own time source, time alignment can be a quite tedious and lengthy process. The need for a new time synchronized measurement device has arrived. The Phasor Measurement Units (PMU) is not only GPS time synchronized, but it also takes measurements as voltage and current phasors. PMUs are becoming an integral part in many power system applications from load flow analysis and state estimation to analyzing blackout causes. Phasor Data Concentrators (PDC) collect and process PMU data. As such, it is important that PMU and PDC communication is seamless. PDCs are set up at multiple utilities and power authorities and also need to be able to communicate and send data to one another seamlessly to encompass analysis of large measurement systems. If these devices are not working similarly when processing and sending/receiving data, unnecessary problems may arise. Therefore it is important that there is an expectation as to how they should work. However, what is expected from these devices is not entirely clear. For this reason, standards such as IEEE C37.118.2-2011 [5] have been proposed to help make operation as uniform as possible. Unfortunately, the standards for PDCs are lacking and tend to only set up communication protocols. To help normalize PDCs, these standards need to be expanded to include all PDC operations and give little room for discrepancy as to what a PDC should do in any given situation. Tests have been performed on PDCs not only to see how they match up to current standards but on how they act outside of the standards. / Master of Science