Application of wide area synchrophasor measurements for improved real-time monitoring and control of power systems

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Date
2016
Authors
Gurusinghe, Dinesh Rangana
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Abstract
This thesis investigates novel ways to utilize the potential of wide area synchrophasors for improved real-time monitoring and control of power systems. The performance of phasor measurement units (PMUs) was examined at the outset, since the accuracy and consistency of synchrophasor applications heavily rely on the input measurements. Two performance class algorithms: P-class and M-class, published in the IEEE standard C37.118.1-2011 were implemented on a commercial PMU and a simple test setup was developed to evaluate it. Tests revealed some inadequacies of the M-class algorithm and remedies were suggested. Moreover, several minor inconsistencies in error limits imposed by the existing synchrophasor standard were found and reported. Two new computationally efficient and stable algorithms for real-time estimation of transmission line parameters were developed. A third algorithm was developed to estimate parameters of series compensated lines. The proposed algorithms were validated through simulations carried out with a real-time digital simulator (RTDS), experiments conducted using a laboratory scale test setup, and using a set of field measurements. The second application is the prediction of transient stability status of a power system after a fault using synchrophasors. A novel algorithm, which utilizes the nature of rate of change of voltage vs. voltage deviation characteristics of the post-disturbance voltage magnitudes obtained from synchrophasors, was proposed. This algorithm is computationally simple and fast compared to the rotor angle based methods, capable of predicting the multi-swing transient instabilities, and pinpoints the generators that become unstable first, which is very useful for emergency controls. Offline and RTDS simulations demonstrated over 99% overall success rate under both symmetrical and asymmetrical faults, and robust performance under changes in pre-disturbance loading and network topology. Finally, a wide area response based emergency generator and load shedding scheme, which operates in conjunction with the prediction algorithm, was developed. A simple method to recognize the unstable cluster of generators using the synchronously measured voltages magnitudes is proposed and the unstable cluster is tripped if the system is predicted unstable. A frequency based load shedding scheme is applied to maintain the generation-load balance. The effectiveness of the approach was demonstrated using the RTDS based experimental test setup.
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Keywords
Synchrophasor measurements, Synchrophasor applications, Phasor measurement unit (PMU), PMU dynamic testing, PMU performance class filters, Measurement errors, Total vector error (TVE), Discrete Fourier transform, Least squares estimation, Transmission line parameters, Real-time digital simulator (RTDS), Transient stability status prediction, Post-disturbance trajectory, Emergency control, Load shedding
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