Online monitoring & mitigation of voltage instability in transmission and distribution systems using synchrophasors

dc.contributor.advisor Ajjarapu Venkataramana Ramapuram Matavalam, Amarsagar Reddy
dc.contributor.department Electrical and Computer Engineering 2019-11-04T21:56:29.000 2020-06-30T03:19:11Z 2020-06-30T03:19:11Z Thu Aug 01 00:00:00 UTC 2019 2020-05-12 2019-01-01
dc.description.abstract <p>With the increasing need for economic operation of the power grid, the system is being operated closer to their limits and there is a need to address the increasing risk of voltage instability in the power grid. In this thesis, methods that can monitor and mitigate the both short-term and long-term voltage instability by utilizing Phasor Measurement Units (PMUs), controllable loads and distributed energy resources are proposed.</p> <p>In the first part of the thesis, the fault induced delayed voltage recovery (FIDVR) phenomenon is studied. The FIDVR phenomenon is monitored by the load admittance at the substation PMU. The admittance provides the PMU at the substation with an estimate of the stalled motors and can be used to estimate the time to recovery and determine control actions for voltage recovery within a set amount of time. To test the real-time nature of the method, the FIDVR phenomenon is simulated in a real-time test-bed and is shown to be able to determine the control amount in an online manner. This methodology is extended to analyze FIDVR in distribution networks and to estimate the trajectory sensitivities in an online manner which are used in a linear formulation to result in a voltage recovery that prevent DER disconnection. Finally, In order to handle the dynamics of non-linear 3-ϕ motors, a data-driven surrogate linear dynamical model is estimated from data which is used to monitor both 1-ϕ and 3- ϕ motors for short term voltage instability.</p> <p>In the second part of the thesis, the long term voltage stability phenomenon is studied. A Sensitivity based Thevenin Index (STI) which uses PMU data and (linear) state estimator data is proposed to monitor long term voltage stability. This sensitivity base index can be modified to account for various what-if scenarios (reactive limit reached, line outage, etc.) in a computationally efficient manner. Finally, A 3ϕ long-term voltage stability indicator (VSI) using the idea of a 3ϕ Thevenin equivalent that can identify critical loads in an unbalanced multi-phase system is proposed to account for the impact of distribution networks to long term voltage instability. The estimation of the 3ϕ Thevenin equivalent is formulated as a convex optimization using PMU & μPMU measurements, making it possible to calculate VSI in a model-free online manner.</p>
dc.format.mimetype application/pdf
dc.identifier archive/
dc.identifier.articleid 8552
dc.identifier.contextkey 15681584
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath etd/17545
dc.language.iso en
dc.source.bitstream archive/|||Fri Jan 14 21:25:15 UTC 2022
dc.subject.disciplines Electrical and Electronics
dc.subject.keywords Data Driven Modeling
dc.subject.keywords Delayed Voltage Recovery
dc.subject.keywords Phasor Measurement Units
dc.subject.keywords Thevenin Equivalent
dc.subject.keywords Transmission & Distribution Interaction
dc.subject.keywords Voltage Stability
dc.title Online monitoring & mitigation of voltage instability in transmission and distribution systems using synchrophasors
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication a75a044c-d11e-44cd-af4f-dab1d83339ff Electrical Engineering dissertation Doctor of Philosophy
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