manohar singh

IIT Delhi, Electrical Engineering, Graduate Student

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Papers by manohar singh

Protection coordination in distribution systems with and without distributed energy resources- a review

Protection and Control of Modern Power Systems, 2017

Emission of greenhouse gases and depletion of fossil fuel reserves are two key drivers, which are... more Emission of greenhouse gases and depletion of fossil fuel reserves are two key drivers, which are forcing the mankind to generate the future energy demand from the renewable energy resources. These resources are generally distributed in nature and are directly integrated at distribution levels. Increasing penetration of the distributed energy resources in distribution power networks creates additional operational and control issues. These are mostly regulatory, economical load dispatching, power quality and protection issues. Generally power distribution systems are protected with the help of dedicated over current based protection schemes. But increasing share of distributed energy resources penetration in electric utilities poses a serious threat to the existing protection coordination schemes of the distribution systems. Distributed energy resources connected distribution networks become interconnected in nature and protection coordination schemes, which are designed for unidirectional flow of fault currents become ineffective/non-functional. Therefore, new protection coordination schemes are required for providing the adequate protection coordination for distributed energy resources connected electric power networks. In the available literature, the protection coordination schemes for radial distribution systems and developments in the area of protection coordination are discussed in detail. A thorough review for all these protection coordination schemes for distribution systems with and without distributed energy resources is done in this review article. It includes the analytical and artificial intelligence based techniques application for coordination of protective relays in the distribution systems. The limitations and research gaps in the area of protection coordination schemes are also presented in this review article. The aim of this research paper is to bring all the available research in the area of relay coordination on one platform, so that it will help the emerging researcher to identify the future scope of relay coordination application for distributed energy resources connected distribution systems.

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Voltage current based time inverse relay coordination for PV feed distribution systems

2016 National Power Systems Conference (NPSC), 2016

Integration of distributed energy resources in distribution systems results in change in network ... more Integration of distributed energy resources in distribution systems results in change in network topology and fault currents levels. Particularly in case of solar based distributed energy resources, the fault feeding capability is extremely poor and a very thin margin exists between their loading and fault feeding capabilities. The conventional time inverse over current relays may not accurately and quickly discriminate between the normal loading and fault conditions. This identified protection coordination problem is addressed in this research article, by developing a voltage current based time inverse relay. The operating principle of this proposed relay is based on reduction in nodal voltage and marginal rise in fault feeding capability of PV based distributed energy resource connected with distribution system. The protection coordination problem for voltage current based time inverse relay is formulated as a non-linear optimization problem. In this optimization problem, the fitness function is defined as summation of operating time of all primary relays and non-linear constraints are constituted with five decision variables like time dial setting, over current pickup, voltage pickup and relay parameters. The proposed protection coordination is simulated for 8 bus test system and solved with the help of evolutionary based optimization algorithm. The performance of the proposed voltage current based time inverse relay is compared with conventional relay and observed that their performances are superior to the conventional time inverse over current relays in term of their operating time.

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Protection coordination in grid connected & islanded modes of micro-grid operations

2013 IEEE Innovative Smart Grid Technologies-Asia (ISGT Asia), 2013

In this paper the authors tried to design a under excitation limiter and a power system stabilize... more In this paper the authors tried to design a under excitation limiter and a power system stabilizer which can operate without any kind of interaction. The under excitation limiter (UEL) is intended to prevent reduction of generator excitation to a level where the steady state stability limit or the stator core end-region heating limit is exceeded. The power system stabilizer (PSS) uses auxiliary stabilizing signals to control the excitation system so as to improve power system dynamic performance.

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Sympathetic Trippings Blocking in Over Current Relay Coordination Algorithm during Steady State & Transient Network Topologies

International Journal of Emerging Electric Power Systems, 2016

In this paper an improved over current relay coordination protection technique is proposed. The p... more In this paper an improved over current relay coordination protection technique is proposed. The proposed technique eliminates the sympathetic/nuisance tripping in an interconnected distribution system. Nuisance trippings are eliminated by incorporating the additional selectivity constraints in conventional over current relay coordination problem. Whenever the fault is cleared only from one end of the line in bidirectional fault feed lines, transient network configuration comes into existence. Transient network configuration causes the redistribution of fault in the distribution system and leads to further nuisance tripping of relays. This problem in this paper is solved by minimising the operating time gap between primary relays located at near end and far end of a faulty line to the best minimum possible value. The differential search algorithm is applied for optimization of highly non-linear over current relay coordination problem in this paper. The result presented in this paper ...

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Protection challenges under bulk penetration of renewable energy resources in power systems: A review

CSEE Journal of Power and Energy Systems, 2017

Among different sources of alternate energy, wind and solar are two prominent and promising alter... more Among different sources of alternate energy, wind and solar are two prominent and promising alternatives to meet the future electricity needs for mankind. Generally, these sources are integrated at the distribution utilities to supply the local distribution customers. If the power generated by these sources is bulk, then they are either integrated at the distribution/transmission level or may be operated in an island mode if feasible. The integration of these renewables in the power network will change the fault level and network topologies. These fault levels are intermittent in nature and existing protection schemes may fail to operate because of their pre-set condition. Therefore, the design and selection of a proper protection scheme is very much essential for reliable control and operation of renewable integrated power systems. Depending upon the level of infeed and location of the renewable integration, the protection requirements are different. For low renewable infeed at the distribution level, the existing relay settings are immune from any small change in the network fault current from new incoming renewables. However, bulk renewable infeed requires modification in the existing protection schemes to accommodate the fault current variation from the incoming renewables. For bulk penetration of the renewable, the requirement of modified/additional protection schemes is unavoidable. Adaptive relaying and non-adaptive relaying schemes are discussed in the literature for protection of power networks, which are experiencing dynamic fault currents and frequent changing network topologies. This article presents a detailed review of protection schemes for renewable integrated power networks which includes distribution, transmission and microgrid systems. The merits and demerits of these protection schemes are also identified in this article for the added interest of the readers. The visible scope of advance protection schemes which may be suitable for providing reliable protection for dynamic fault current networks is also explored.

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Optimal coordination of directional overcurrent relays considering definite time backup relaying

IEEE Transactions on Power Delivery, 1999

A methodology is presented for the consideration of definite-time backup relays in the optimal co... more A methodology is presented for the consideration of definite-time backup relays in the optimal coordination of directional overcurrent relays using linear programming. It is shown that the influence of considering second-zone distance relays and breaker failure relays impose important requirements for the determination of the time dial settings of directional overcurrent relays. The paper introduces a revised formulation of the optimization problem. Results are presented for the application of the methodology on a power system with 2 generators, 9 buses, 2 transformers and 7 transmission lines.

Minimization of operating time gap between primary relays at near and far ends in overcurrent relay coordination

2014 North American Power Symposium (NAPS), 2014

In bidirectional fault feed distribution lines, the fault should be cleared from both the fault f... more In bidirectional fault feed distribution lines, the fault should be cleared from both the fault feeding sources ends simultaneously, so that impact of faults currents on the exiting over current relay coordination will be minimum. In existing over current relay coordination algorithms, it is observed that operating time gaps between primaries over current relays at near end and far end of faulted line are quite enough. This time gaps may redistribute the fault currents in the power networks which leads to cascading type of over current relay miscoordination in a properly coordinated power network. In this paper, the over current relay coordination problem formulation is modified in such a way to minimize the operating time gap between the primary over current relays at near and far ends with in a desired time margin such that the chance of redistribution of fault currents in the distribution network is eliminated. The proposed modified over current relay coordination algorithm is implemented in 8 bus test distribution system.

Optimal overcurrent relay coordination in distribution system

2011 International Conference on Energy, Automation and Signal, 2011

ABSTRACT Coordination of overcurrent relays in a meshed distribution system is a challenge task f... more ABSTRACT Coordination of overcurrent relays in a meshed distribution system is a challenge task for the protection engineers. Initially it was done manually. Linear and non-linear programming optimizing techniques are very frequently used for Coordination of overcurrent relays. Presently artificial intelligence is applied for optimal co-ordination of Overcurrent (OC) relays. This paper discusses application of genetic algorithm for optimal coordination of OC relays in a loops distribution system. Combination of primary and backup relay is chosen by using graph theory, to avoid misoperation of relays.

Optimum Coordination of overcurrent relays using CMA-ES algorithm

2012 IEEE International Conference on Power Electronics, Drives and Energy Systems (PEDES), 2012

Electrical Systems are seldom subjected to excessive currents caused due to short circuits and gr... more Electrical Systems are seldom subjected to excessive currents caused due to short circuits and ground faults. Therefore, it is mandatory to protect people and primary electric power equipment from damage or disaster using suitable Protective systems. When the current exceeds the threshold level, Overcurrent (OC) Relay is operated. It is important for a protection engineer to maintain coordination time interval (CTI) among relays during overcurrent relay coordination. For quick clearance of faults, various optimization algorithms are applied to relay parameters. In this paper, Genetic algorithm and particle swarm optimization technique are used to deduce the Time Multiplier Setting (TMS) values of relays implemented on a radial network. This aids in achieving suitable OC coordination of relays.

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Short Circuit Modelling and Analysis of PV Inverters in Large Solar Farms

Power Research - A Journal of CPRI

The short circuit behavior of solar farms are different from conventional generating stations. Th... more The short circuit behavior of solar farms are different from conventional generating stations. These generating resources arestatic in nature and have a rich power electronic interface with a grid, limiting these solar farms’ short circuit capabilities.The solar inverter voltage versus short circuit current characteristics is modeled to supply the fault current within inverterdesigned ratings. In this research paper, a large number of solar power investors are grouped to pool their power into thegrid. Short circuit studies are carried out for a 500 MW solar farm with string inverters rating of 3125 kW per IEC 60909.The protective relaying coordination is performed as per IEEE C37.90 and IEC 60255-1 relaying standard.

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Enhanced real time coordination of distance and user defined over current relays

International Journal of Electrical Power & Energy Systems

Faults on the transmission lines are primarily cleared by pilot wire differential protection as w... more Faults on the transmission lines are primarily cleared by pilot wire differential protection as well as from zone-1 and zone-2 of distance relays, depending upon their location on the lines. If the main distance relays fails to operate, then standard time inverse directional over current (DOCR) relays are set as backup protection in coordination with main distance relays. The desired coordination time margins between main distance relays and backup standard time inverse over current relays should be maintained at start of zone-1 and zone-2 of distance relays. Coordination of fixed zone-2 setting of distance relays with standard time inverse relays results in poor tripping time of backup DOCR. In this research article, zone-2 setting of distance relays are made adaptive, so that minimum coordination time margin is maintained for complete reach of distance relays. User defined time inverse over current relays are proposed in conjugation with flexible feature of zone-2 setting of distance for improving the operating time of backup DOCRs. The performance of the proposed algorithm is validated in real time simulation with hardware in loop testing of numerical distance and user defined DOCR. From hardware in loop simulation results, it is observed that the performance of the proposed combined distance & DOCR coordination algorithm is in close concurrence with simulated results. The sensitivity of proposed algorithm is checked for different phase as well as ground faults with different fault resistance and it is also observed that the proposed algorithm is highly robust for different fault conditions.

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The oscillations and the stability of rotating masses with magnetic fields

Astrophysics and Space Science, 1975

The oscillations and the stability of rotating gaseous masses have been extensively investigated ... more

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Optimization of Process Parameters for the Photocatalytic Degradation of 2,4Dichlorophenol in Aqueous Solutions

International Journal of Chemical Reactor Engineering - INT J CHEM REACT ENG, 2009

Page 1. INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING Volume 7 2009 Article A6 Optimizati... more

The equilibrium and the stability of the Jeans spheroids with toroidal magnetic fields

Astrophysics and Space Science, 1978

We examine the effect of a toroidal magnetic field on the equilibrium and stability of homogeneou... more We examine the effect of a toroidal magnetic field on the equilibrium and stability of homogeneous masses distorted by the tidal effects of a secondary (of massM' at a distanceR). It is shown that if the toroidal magnetic field is assumed to be axisymmetric about the direction of the line joining the centres of mass of the primary and the secondary, then the equilibrium configuration is a prolate spheroid. Also determined are the characteristic frequencies of the various modes of oscillations belonging to the second harmonics. It is found that the magnetic field shifts these frequencies to higher values than the ones which prevail in the absence of a magnetic field.

Tannins: their adverse role in ruminant nutrition

Journal of agricultural and food chemistry, 1984

Van Cantfort, J.; Graeve, JD; Gielan, JE Biochem. Biophys. ... Wade, AE; Norred, WP Fed. Proc., F... more

Feed utilisation by various breeds of sheep exposed to high environmental temperature

Tropical Animal Health and Production, 1978

Feed utilisation in sheep has been reported to be affected by environmental temperature condition... more Feed utilisation in sheep has been reported to be affected by environmental temperature conditions. The present investigation was conducted to find if there were any breed group differences in feed intake and utilisation under high ambient temperature. In a climatic chamber four trials were conducted on 20 male yearlings of Rambouillet (R), Malpura (M), Chokla (C), R x M{ and