Browsing by Author "Rovnyak, Steven M."

Now showing 1 - 5 of 5
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    Algorithms for Detecting Nearby Loss of Generation Events for Decentralized Controls
    (IEEE Xplore, 2021-04) Dahal, Niraj; Rovnyak, Steven M.; Electrical and Computer Engineering, School of Engineering and Technology
    The paper describes algorithms to screen realtime frequency data for detecting nearby loss of generation events. Results from Fourier calculation are combined with other features to effectively distinguish a nearby loss of generation from similar remote disturbances. Nearby in this context usually refers to an event occurring around 50-100 miles from the measurement location. The proposed algorithm can be trained using pattern recognition tools like decision trees to enable smart devices including appliances like residential air conditioners and dryers to autonomously detect and estimate the source of large frequency disturbances. An area of application of this strategy is to actuate controls such as location targeted under frequency load shedding (UFLS) so that loads closest to a tripped generator are the most likely to shut down.
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    ANGLE STABILITY PREDICTIONS
    (Office of the Vice Chancellor for Research, 2012-04-13) Nilchi, Maryam N.; Longbottom, Daniel W.; Vasquez, Diana C.; Rovnyak, Steven M.
    The variance of phase angle changes over the network is a good display of total stress and angle stability. The integral square generator angle (ISGA) changes had been recommended earlier to evaluate how severe the stable and unstable transient contingencies in simulation are. This project offers its addition to bus voltage angles (ISBA) which could be measured with synchronized phasor measurement units (PMUs) over a wide-ranging area. By restructuring continuous paths that go outside the boundary be-tween positive and negative 180 degrees before calculating the ISBA, the cutoff of bus angles at positive and negative 180 degrees is recovered. The project also directs the matter of obtaining the best angle stability index as the threshold between stable and unstable classes with use of simulation da-ta. This issue becomes more difficult by the fact that large databases might include a few events for which loss of synchronism happens toward the end of the simulation sequence.
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    Applying Different Wide-Area Response-Based Controls to Different Contingencies in Power Systems
    (IEEE Xplore, 2021) Iranmanesh, Shahrzad; Rovnyak, Steven M.; Electrical and Computer Engineering, School of Engineering and Technology
    Electrical disturbances in the power system can threaten stability. One-shot control is an effective method for stabilizing some events. In this paper, predetermined amounts of loads are increased or decreased around the network. Determining the amounts of loads, and the location for shedding is crucial. This paper is completed in two different sections. First, finding the effective control combinations, and second, finding an algorithm for applying different control combinations to different contingencies in real time. The particle swarm optimization (PSO) algorithm is used to find the effective control combinations. Next, decision trees (DT) are trained to assess the benefits of applying each of the three most effective control combinations found by PSO method. The DT outputs are combined into an algorithm for selecting the best control in real time. Finally, the algorithm is evaluated using a test set of contingencies. The results reveal a 46% improvement in comparison to previous studies.
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    Introducing a Concise Formulation of the Jacobian Matrix for Newton-Raphson Power Flow Solution in the Engineering Curriculum
    (IEEE Xplore, 2021-04) Conlin, Elijah; Dahal, Niraj; Rovnyak, Steven M.; Rovnyak, James L.; Electrical and Computer Engineering, School of Engineering and Technology
    The power flow computer program is fundamentally important for power system analysis and design. Many textbooks teach the Newton-Raphson method of power flow solution. The typical formulation of the Jacobian matrix in the NR method is cumbersome, inelegant, and laborious to program. Recent papers have introduced a method for calculating the Jacobian matrix that is concise, elegant, and simple to program. The concise formulation of the Jacobian matrix makes writing a power flow program more accessible to students. However, its derivation in the research literature involves advanced manipulations using higher dimensional derivatives, which are challenging for dual level students. This paper presents alternative derivations of the concise formulation that are suitable for undergraduate students, where some cases can be presented in lecture while other cases are assigned as exercises. These derivations have been successfully taught in a dual level course on computational methods for power systems for about ten years.
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    Performance of Response Based One Shot Controls Handling Missing Phasor Measurements
    (IEEE, 2020-08) Dahal, Niraj; Rovnyak, Steven M.; Electrical and Computer Engineering, School of Engineering and Technology
    With the advent of real-time PMU data acquisition technology, the possibility of solutions to several instability problems in power system has increased. However, PMUs may undergo different data quality issues like recording bad data or missing data. Some paper mentions about 5-10% of missing samples in some historical PMU's dataset. This paper assumes 0-10% of missing phasor samples by randomly deleting measurements and explores imputation methods of handling missing data in real time. The simulation is carried out in a DT-based stability prediction and one-shot control scheme of WECC's 176-bus model. Several control performances are evaluated to decide a useful method of missing data recovery for the response based one shot control scheme. A PMU data quality issue is not limited to missing samples only but also interference with noises. Later part of this paper performs simulation considering noisy phasor measurements. A 45 dB of Gaussian distributed noise is deliberately added to phasor samples and simulation is performed with different DT indices and thresholds for real time stability prediction and control actuation.