Faculty Publications
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Item Computer controlled intrusion-detector and automatic firing-unit for border security(2010) Vittal, K.P.; Ajay, P.P.; Shenoy, S.B.; Srinivas Rao, C.H.S.This paper describes a novel computer-controlled intrusion-detector and automatic firing unit, which may be used for the surveillance of borders, either of a country, or of areas requiring high security, especially in regions of extreme climatic conditions, where it is difficult to deploy personnel. This system not only detects intrusion but also provides a video-coverage of the suspicious area, for remote vigilance, via a satellite based communication system. It is also provided with automatic firing mechanisms which can be used to automatically locate and fire at the target. Thus, several kilometres of the borders, which would have otherwise required several hundred personnel, can be effortlessly monitored with this system, with only a few personnel. Since, the actual firing occurs only after an authoritative personnel has doubly confirmed the presence of an intruder, chances of firing at innocent people are completely ruled out. As thermal cameras are used for imaging, this system is immune to changes in ambient conditions, and therefore, is equally suited for operation during the night. This paper also throws light on the prototype of this system, which has been successfully developed. © 2010 IEEE.Item Adaptive Protection of Solar PV Microgrid Without ESS(Springer Science and Business Media Deutschland GmbH, 2024) Meitei, L.P.; Vittal, K.P.; Pinto, J.A.Conventional sources play a major role in today’s power scenario. However, the trend has now been shifted toward non-conventional sources, viz., Solar, wind, tidal, etc. considering the depletion rate of fossil fuels, transmission losses and environmental impacts. As a result, Microgrids are getting popular nowadays due to its high reliability, nature of operation, and low operational cost. In this paper, an adaptive protection scheme is developed in MATLAB for a solar PV Microgrid without Energy Storage Systems (ESS) which can operate in both Grid connected mode (GCM) and Islanded Mode (IM). © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2024.Item DC Fault Protection in Multi-terminal VSC-Based HVDC Transmission Systems with Current Limiting Reactors(Korean Institute of Electrical Engineers, 2019) Muniappan, M.; Vittal, K.P.Multi-terminal VSC-based HVDC transmission system is the recent interest for grid integration of large-scale offshore wind farms. Protection of multi-terminal voltage source converters (VSC)-based HVDC transmission systems against DC faults is challenging. This paper presents a single-ended protection scheme for DC faults in a three-terminal VSC-HVDC transmission system. The under-voltage criterion is used to distinguish the DC faults from the transient and normal conditions. The rate of change of DC voltage and current as well as the variation of transient energy is used to discriminate the internal faults from the external faults. The DC fault current has very high value within a few milliseconds during the transient phases such as the capacitor discharging and diode freewheeling stages. Therefore, current limiting reactors are introduced in series with the DC circuit breaker to maintain the DC fault current within the breaker capacity. The single-ended protection scheme is tested with the three-terminal VSC-HVDC transmission system with current limiting reactors for various DC fault conditions. The DC fault data is generated from PSCAD/EMTDC simulation and the protection scheme is tested in MATLAB environment. Test results show that the proposed protection scheme gives reliable protection for the DC faults in a three-terminal VSC-HVDC transmission system. © 2019, The Korean Institute of Electrical Engineers.Item Protection schemes for a battery energy storage system based microgrid(Elsevier Ltd, 2022) Joshua, A.M.; Vittal, K.P.This paper evaluates directional and adaptive overcurrent protection schemes in microgrids. A microgrid supported by a centralised Battery Energy Storage System (BESS) is chosen for the study. The stringent PQ controller of BESS will not allow it to dissipate into a fault, during its charging mode, causing the conventional directional schemes to mal-operate. A direction estimation scheme using magnitude and angle of superimposed positive sequence impedance is proposed to address this issue in BESS. Further, two fault detection techniques are proposed for BESS integrated feeders. The Main Protection Unit (MPU) detects an internal fault when there is a mismatch in the direction of relays at either end of a feeder. The second scheme uses adaptive overcurrent relay settings. Since the fault current is limited with PQ control, the pickup current is calculated dynamically with this control. Whereas a fixed pickup current is chosen, when the BESS inverter is voltage controlled. Simulations have been carried out using MATLAB/SIMULINK software. The proposed schemes work well for bidirectional power flows and in grid connected and standalone modes of microgrid operation. © 2021Item Incremental transient power-based protection scheme for a DC microgrid(Springer Science and Business Media Deutschland GmbH, 2022) Joshua, A.M.; Vittal, K.P.A key step in the realisation of DC microgrids is the development of robust protection schemes. Bidirectional power flow in ring-type configurations makes protection design too complicated. This paper presents an algorithm for selective fault location and isolation of faulty parts in the transient stage itself. At the onset of a fault, the proposed scheme computes incremental transient power (Δ P) from initial changes in voltage and current. The sign of Δ P captured by different IEDs is compared to determine the fault location. Though the scheme is designed for the unit protection of feeders, it is also capable of locating and isolating external faults accurately. A backup scheme using local measurements is provided, in case of communication failure. The schemes are simulated using extensive simulations in MATLAB/SIMULINK platform. The results confirm that the proposed protection design operates within a few milliseconds and is highly selective and stable. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item Superimposed current based differential protection scheme for AC microgrid feeders(Elsevier Ltd, 2023) Joshua, A.M.; Vittal, K.P.Legacy protection schemes face numerous challenges with the emergence of microgrids. Due to the complex controls, the fault responses in microgrids differ from conventional behaviour and vary with the operation mode. In this paper, a differential protection scheme based on fundamental frequency superimposed current phasors is proposed for microgrid feeders. The phasors are extracted using dq components instead of conventional Fourier algorithms. The performance of proposed method is tested for different fault scenarios by carrying out simulations in MATLAB/SIMULINK software. The results confirm that internal faults are detected in a few milliseconds. At the same time, the scheme remains insensitive to external faults with CT saturation and other system disturbances. The proposed scheme is unaffected by the microgrid mode of operation, direction of power flow and DG type. © 2023 Elsevier Ltd