Browsing by Subject "Power systems"
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Item Analysis of transmission system events and behavior using customer-level voltage synchrophasor data(2013-05) Allen, Alicia Jen; Santoso, SuryaThe research topics presented in this dissertation focus on validation of customer-level voltage synchrophasor data for transmission system analysis, detection and categorization of power system events as measured by phasor measurement units (PMUs), and identification of the influence of power system conditions (wind power, daily and seasonal load variation) on low-frequency oscillations. Synchrophasor data can provide information across entire power systems but obtaining the data, handling the large dataset and developing tools to extract useful information from it is a challenge. To overcome the challenge of obtaining data, an independent synchrophasor network was created by taking synchrophasor measurements at customer-level voltage. The first objective is to determine if synchrophasor data taken at customer-level voltage is an accurate representation of power system behavior. The validation process was started by installing a transmission level (69 kV) PMU. The customer-level voltage measurements were validated by comparison of long term trends and low-frequency oscillations estimates. The techniques best suited for synchrophasor data analysis were identified after a detailed study and comparison. The same techniques were also applied to detect power system events resulting in the creation of novel categories for numerous events based on shared characteristics. The numerical characteristics for each category and the ranges of each numerical characteristic for each event category are identified. The final objective is to identify trends in power system behavior related to wind power and daily and seasonal variations by utilizing signal processing and statistical techniques.Item Dynamic models for wind power plants(2011-08) Singh, Mohit, 1982-; Santoso, Surya; Grady, William M.; Driga, Mircea; Muljadi, Eduard; Longoria, Raul G.Manufacturer-specific models of wind turbines are favored for use in wind power interconnection studies. While they are detailed and accurate, their usages are limited to the terms of the non-disclosure agreement, thus stifling model sharing. The primary objective of the work proposed is to develop universal manufacturer-independent wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Each of these models includes representations of general turbine aerodynamics, the mechanical drive-train, and the electrical characteristics of the generator and converter, as well as the control systems typically used. In order to determine how realistic model performance is, the performance of the one of the models (doubly fed induction generator model) has been validated using real-world wind power plant data. This work also documents selected applications of these models.Item Time-domain modeling of distribution and transmission line protection(2007-12) Allen, Alicia Jen; Santoso, SuryaPower system protective relay and fuse models have been used to evaluate performance of new and existing designs and schemes, and to assist in designing new relays. Normally, to evaluate relay performance, relay manufacturers and utility distribution and transmission industry users perform expensive and time consuming tests. The testing of electromechanical and microprocessor based relays requires costly equipment to inject analog current and voltage waveforms into the relay. As an alternative, a model of the protective device can be tested in a timedomain power system model to predict relay behavior. Time-domain modeling is ideal for this task since it is capable of modeling transient events. Data from the power system model provides input signals for the relay model, removing the need for expensive equipment. In this thesis, new time-domain models have been developed to predict behavior of distribution protection such as fuses, reclosers, and sectionalizers. Existing dynamic testing of distribution protection models from literature are based on steady-state phasor solutions and ignore any transient effects. Simple relay components already exist in time-domain simulation software. These can be used to create a basic distance relay model. However, the existing components are insufficient for modeling distance protection accurately as their performance suffers under real world conditions such as the presence of fault resistance and load current. In this thesis, a more realistic model that closely emulates the physical operation of a distance relay is developed than is currently documented in the literature. The model described in this thesis significantly reduces the amount of underreach when fault impedance is present by incorporating the polarizing voltage used in real-world electromechanical and microprocessor based distance protection. Testing of the new relay model under a variety of fault and load conditions showed improved reach accuracy. Other benefits of time-domain protection models include the ability to extensively test a variety of scenarios and generate waveform data for power system studies.