Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
5 results
Search Results
Item Synchrophasor Measurement Standard Comparison and Testing of an FF-based PMU(Institute of Electrical and Electronics Engineers Inc., 2020) Aalam, M.K.; Shubhanga, K.N.Phasor Measurement Units (PMUs) are an integral part of Wide Area Measurement Systems (WAMS). The PMU algorithms need to be tested before they are utilized for monitoring, control and protection applications. In this context, understanding the test procedures suggested by the IEEE standard for synchrophasor measurement is very essential. This paper looks into the standards, with emphasis on the differences between the 2011 version and the 2014 update. In this paper, the IEEE standard based test procedures are listed and detailed in such a way that they can be readily applied to test any PMU algorithm for compliance verification. The steady-state and dynamic tests given in the standard are performed, using the Fourier Filter (FF) algorithm and results are compared with the permissible limits. Finally the performance of the FF is verified using realistic signals obtained from a 4-machine 10-bus system during fault conditions. © 2020 IEEE.Item EMD based Detrending of Non-linear and Non-stationary Power System Signals(Institute of Electrical and Electronics Engineers Inc., 2021) Aalam, M.K.; Shubhanga, K.N.In electromechanical modal analysis of power systems using Wide Area Measurement System (WAMS) based setup, signal processing is complex as the signals are non-stationary and non-linear in nature. In order to get accurate modal parameters, as a first step, it is required to remove the non-linear trend of the signal. In the literature, many conventional methods such as filtering, averaging and peak detection techniques are employed for removing trend. In this paper, Empirical Mode Decomposition (EMD) method, an iterative algorithm is presented to detrend a signal. The EMD method and its variant are compared with another popularly used peak detection method referred to as the Zhou's detrending algorithm to find the efficacy of the EMD methods. To test the algorithms, a four machine, two-area power system with three-wind farms is modeled and simulated to generate the power system signals which bring out non-linear and non-stationary nature. Further, the modal characterization is carried out employing Prony analysis. © 2021 IEEE.Item An integrated PMU architecture for power system applications(De Gruyter Open Ltd, 2022) Aalam, M.K.; Shubhanga, K.N.Time synchronized phasors obtained using Phasor Measurement Units (PMU) spread across wide areas have revolutionized power system monitoring and control. These synchronized measurements must be accurate and fast in order to comply with the latest IEEE standards for synchrophasor measurements. The speed at which a PMU provides an output depends on the group delay associated with that PMU and the permissible group delay in-turn decides the utility of a PMU for either control or measurement application. Based on the group delay compensation techniques, in the literature, two individual types of PMUs, such as causal and non-causal PMUs have been introduced. This paper presents an approach where both causal and non-causal PMUs are combined in an integrated PMU architecture. This method not only illustrates the group delay performance of two PMUs in a single module, but also can be used for multiple functions. In this environment several PMU algorithms have been compared with respect to their group delays and their effect on the response time. Application of the integrated PMU architecture to a four-machine 10-bus power system has been demonstrated using a six-input PMU with three-phase voltage and current signals as inputs. Different causal compensation schemes are introduced due to the availability of voltage and current-based frequency and ROCOF signals. Impact of these compensation schemes on PMU accuracy is evaluated through the Total Vector Error (TVE) index. The influence of these compensation schemes on measurements like power and impedance is also investigated. Finally, outputs from the integrated PMU architecture are fed into a Power System Stabilizer (PSS) to control the small-signal stability performance of a power system during dynamic conditions. © 2021 Walter de Gruyter GmbH, Berlin/Boston.Item Power system event detection and localization—A new approach(Elsevier Ltd, 2023) Aalam, M.K.; Shubhanga, K.N.Time-synchronized estimates acquired using the Wide Area Measurement System (WAMS) have substantially helped enhance the health of the modern power grid. WAMS data when used in conjunction with appropriate tools can aid in the timely detection of power system events. With the continuous expansion of the WAMS network, identification of events and narrowing down on their location is emerging as a serious challenge for power system operators. Therefore, in this paper an event detection and localization tool is developed which analyzes data obtained from multiple Phasor Measurement Units (PMUs) installed throughout the WAMS network in order to identify the occurrence of an event. The effectiveness of this tool is demonstrated using practical signals from the ISO-NE power system and simulation based signals obtained from a 4-machine 10-bus system. Occurrence of an event is flagged by comparing the wavelet energy and standard deviation values of a PMU signal against a threshold. An event localization algorithm based on the number of PMUs involved in the event detection stage is proposed. Based on the presented algorithm, disturbances are classified as local or wide-spread events. Finally, a method to identify a loss-of-synchronism condition using phase angle difference (PAD) signals obtained across transmission lines is also proposed. © 2023 Elsevier B.V.Item Frequency estimation using signal reconstruction approach(Elsevier Ltd, 2024) Aalam, M.K.; Shubhanga, K.N.Frequency estimated throughout the wide-spread grid is used for monitoring and controlling various local as well as global power system phenomena. Such applications require precise frequency estimation, especially during challenging power system conditions when signals are non-stationary or contain harmonics. Therefore, in this paper, a signal-reconstruction-based approach has been described to estimate the frequency and rate-of-change of frequency (ROCOF) for a single-phase system. The approach is based on the idea that the frequency information in case of a reconstructed signal is preserved even during off-nominal frequency conditions. Single-phase reconstructed time-domain signals are proposed as an alternative to phase-angle signals for frequency estimation. From the reconstructed time-domain signals, the frequency is estimated using the convolution average filter (CAF) based method and a single-phase demodulation technique employing Hilbert filter (HFD). The effectiveness of this approach especially during off-nominal and inter-harmonic conditions is demonstrated using the synchrophasor standard based test signals. The proposed method is compared against state-of the art single-phase phasor measurement unit based estimates. Accuracy of the reconstruction-based approach is also verified through signals obtained from the ISO-New England power system and simulation based studies. The output frequency and ROCOF signals are also used for mode identification using the Prony method. © 2023 Elsevier B.V.