Publications

  • Nitin Narang, J.S. Dhillon, D.P. Kothari
    International Journal of Electrical Power & Energy Systems 01/2014; 62:665–678. · 3.43 Impact Factor
  • Nitin Narang, J.S. Dhillon, D.P. Kothari
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    ABSTRACT: Paper presents predator–prey based optimization (PPO) technique to obtain optimal generation scheduling of short-term hydrothermal system. PPO is a part of the swarm intelligence family and is capable to solve large scale non-linear optimization problems. PPO based algorithm combines the idea of particle swarm optimization concept with predator effect that helps to, maintain diversity in the swarm and preventing premature convergence to local sub-optimal. In this paper first of all feasible solution is obtained through random heuristic search and then thermal and hydro power generations are searched for optimum hydrothermal scheduling problem using PPO. Variable elimination method is implemented to handle the equality constraint by eliminating variable explicitly. These eliminated variables are considered by penalty method restricts slack units with in limits. Slack thermal generating unit for each sub-interval handles power balance equality constraint and slack hydro units handle water equality constraint. The performance of the proposed approach is illustrated on, fixed-head and variable-head hydrothermal power systems. The results obtained from the proposed technique are compared with the existing technique. From the numerical results, it is experienced that the PPO based approach is able to provide a better solution.
    Applied Soft Computing. 01/2014; 21:298–308.
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    ABSTRACT: In this paper, different Distribution Static Compensators (DSTATCOMs) topologies, state of the art, their performance, design considerations, future developments, and potential applications are investigated for power quality improvement. These DSTATCOMs for three-phase three-wire systems and three-phase four-wire systems are developed and installed in the distribution system for many functions, such as reactive power compensation, harmonics elimination, load balancing, and neutral current compensation. This paper is aimed to explore a broad perspective on DSTATCOMs to researchers, engineers, and the community dealing with the power quality improvement. A classified list of some latest research publications is also provided for quick reference.
    IEEE Transactions on Industrial Informatics 01/2014; 10(2):854-870. · 8.79 Impact Factor
  • H.P. Singh, Y.S. Brar, D.P. Kothari
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    ABSTRACT: Major objective for the Thermal power generation is to minimize fuel consumption by allocating optimal power generation from each unit and to maintain emissions within the environmental license limit subject to equality and inequality constraints. The objectives considered in this paper for minimization i.e. cost and emission are of conflicting nature, therefore weighting method has been applied to convert multiobjective optimization problem to a scalar optimization. The weighting method assigns different weights to each objective function based upon their importance. The Particle Swarm Optimization (PSO) technique has been applied to find the best comprised solution. The equality constraints have been handled by exterior penalty method. Fuzzy cardinal approach has been used for the evaluation of the best solution. In order to show the effectiveness, the proposed approach has been tested on three test systems. Numerical results obtained from the proposed approach are compared with different techniques.
    Industrial Electronics and Applications (ICIEA), 2013 8th IEEE Conference on; 01/2013
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    ABSTRACT: In the deregulated electricity market, it has become very important to determine the complete information about the participants who are utilizing the transmission network. Transmission line usage computation requires information of generator to load contributions and the path used by various generators to meet loads and losses. In the present restructured electricity market, it is necessary to develop appropriate pricing techniques that can provide the useful economic information to market participants. In this paper, the three existing techniques namely Zbus method, Zbusavg method and Relative Electrical Distance (RED) method for the network cost allocation is compared. It has been successfully applied on an IEEE 24 bus-Reliability Test System (RTS) and the results obtained are compared. The results obtained are quite encouraging and useful for the deregulated electricity market related issues. The simulation is carried out using MATLAB 7.8.0 (R 2009a).
    Power, Energy and Control (ICPEC), 2013 International Conference on; 01/2013
  • Nitin Narang, J.S. Dhillon, D.P. Kothari
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    ABSTRACT: An integrated methodology that embeds global and local search technique is explored for solving multiobjective hydrothermal scheduling. Predator-prey optimization (PPO) is used as a base level search in the global search space and Powell's method as a local search technique. Predator-prey model is based on particle swarm optimization (PSO). In spite of several advantages of PSO as compared to other evolutionary methods, it has some major drawbacks such as local optimal trapping and lack of efficient capability to treat the constraints. PPO model includes predator and prey particles in population. The prey objective is to escape from the predators reaching to its lair, while predator's goal is to capture the prey that increase exploration and exploitation capability of PSO. Powell's method aims to fine tune the solution obtained from PPO and to enhance the search capability of proposed method. In addition, a penalty less constraint handling method is employed for considering equality and inequality constraints. Fuzzy methodology has also been exploited to find the best compromised solution. The proposed integrated technique is applied to three hydrothermal scheduling problems with valve-point effect of thermal generators and transmission losses. The proposed method yields high quality solution while satisfying all constraints.
    Energy 11/2012; 47(1):237–252. · 4.16 Impact Factor
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    ABSTRACT: This paper describes an algorithm for optimum modifications for failure rate and repair time for a radial electrical distribution system. The modifications are with respect to a penalty cost function minimization. The cost function has been minimized subject to the energy based and customer oriented indices, i.e. AENS, SAIFI, SAIDI and CAIDI. Coordinated aggregation based particle swarm optimization (CAPSO) has been used for optimization. The algorithm has been implemented on a sample radial distribution system. The results obtained have been compared with those obtained using PSO.
    Applied Soft Computing. 11/2012; 12(11):3325–3331.
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    ABSTRACT: In power system studies, congestion in transmission lines and utilization of Flexible Alternating Current Transmission System (FACTS) devices are closely associated and it is very important due to their role in power delivery system enhancement. It is to be noted that the generation companies can exercise their market power which depends on the line flows and the line constraints, generators' location and its share to the individual loads. This issue cannot be overlooked as it creates monopoliness which is a threat to the deregulated market policy. The objective of this paper is to show how the generation companies' market power gets enhanced due the FACTS devices. FACTS devices like Thyristor Controlled Switching Capacitor (TCSC) and Thyristor Controlled Phase Angle Regulator (TCPAR) are taken and used under steady state operation. The market power is determined using Nodal Must Run Share (NMRS) index for the standard IEEE 14bus system with and without the above FACTS devices and the results obtained are compared. All the above simulations are carried out in MATLAB 7.9R2009b environment.
    India Conference (INDICON), 2012 Annual IEEE; 01/2012
  • Nitin Narang, J. S. Dhillon, D. P. Kothari
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    ABSTRACT: In this article, a predator–prey-based optimization technique is applied to obtain the scheduling of a hydrothermal system with cascaded reservoirs, minimizing economic and gaseous pollutants and emission objectives. These objectives are mutually conflicting and are equally important. Predator–prey optimization is a stochastic optimization technique based on the particle swarm optimization concept having an additional predator effect that helps to explore the search area more efficiently due to the fear created by the predator. A heuristic search technique is applied for generating an initial feasible solution. The direct substitution method is implemented to handle the equality constraints, whereby dependent variables are determined from the equality constraint. Inequality constraints of dependent variables are taken care by incorporating an additional objective function represented by the fuzzy membership index, and other variables are set to their limits on violation. Fuzzy methodology has been exploited for solving a decision-making problem involving the multiplicity of objectives and selection criterion for the best compromised solution. The solutions obtained from the proposed technique are compared with other existing techniques, and results are found to be satisfactory. The proposed method has the capability to escape from local optimum solutions due to its predator effect, and it is easy to implement.
    Electric Power Components and Systems 01/2012; 40(15). · 0.62 Impact Factor
  • P Jayaprakash, Bhim Singh, D P Kothari
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    ABSTRACT: In this paper, a new topology of DSTATCOM using three single-phase VSCs (voltage source converters) integrated with a zig-zag transformer is employed for the power quality improvement in three-phase four-wire distribution systems. The zig-zag transformer is used for providing a path to the zero sequence fundamental as well as harmonics currents. In order to optimize the voltage rating of the VSCs, the zig-zag transformer is designed to have a tertiary winding for integrating the VSCs. This new topology of DSTATCOM (Distribution Static Compensator) provides the voltage regulation or power factor correction by reactive power compensation, harmonics compensation, load balancing and neutral current compensation in three-phase four-wire distribution system. This topology has the advantages of the use of ‘off the shelf’ VSC, reduced kVA rating, optimum voltage rating of VSCs and hence less cost. The VSCs are integrated with a zig-zag transformer to realise a single unit by designing a set of third winding in the transformer. The performance of the proposed DSTATCOM system is demonstrated under linear and nonlinear balanced and unbalanced loads by simulation using MATLAB with its Simulink and simpower systems (SPS) tool boxes
    01/2012;
  • B. Singh, P. Jayaprakash, S. Kumar, D.P. Kothari
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    ABSTRACT: In this paper, a neural-network (NN)-controlled distribution static compensator (DSTATCOM) using a dSPACE processor is implemented for power quality improvement in a three-phase four-wire distribution system. A three-leg voltage-source-converter (VSC)-based DSTATCOM with a zig-zag transformer is used for the compensation of reactive power for voltage regulation or for power factor correction along with load balancing, elimination of harmonic currents, and neutral current compensation at the point of common coupling. The Adaline (adaptive linear element)-based NN is used to implement the control scheme of the VSC. This technique gives similar performance as that of other control techniques, but it is simple to implement and has a fast response and gives nearly zero phase shift. The zig-zag transformer is used for providing a path to the zero-sequence current in a three-phase four-wire distribution system. This reduces the complexity and also the cost of the DSTATCOM system. The performance of the proposed DSTATCOM system is validated through simulations using MATLAB software with its Simulink and Power System Blockset toolboxes and hardware implementation.
    IEEE Transactions on Industry Applications 09/2011; · 1.67 Impact Factor
  • B. Singh, P. Jayaprakash, D.P. Kothari
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    ABSTRACT: In this paper, a number of methods for neutral current compensation using magnetics are proposed and these are compared with reported techniques. The proposed neutral current mitigation techniques include a Scott-transformer, T-connected transformer, star-hexagon transformer and star-polygon transformer designed for mmf (magneto motive force) balance. These transformer configurations along with the conventional transformer configurations such as a star-delta transformer and a zig-zag transformer are analysed, designed, simulated and verified by developing prototypes. The transformers provide a path to the zero sequence fundamental as well as harmonics currents. Two single phase transformers are required for the proposed Scott-connection and T-connection where as three single phase transformers are required in other methods. The neutral current compensation schemes using transformers are modeled and simulated using MATLAB with its Simpower systems (SPS) toolboxes and compared to demonstrate the effectiveness of the proposed transformers. Laboratory prototypes of the transformers are developed and their test results are presented to validate the design of transformers for neutral current compensation.
    Power Electronics, Drives and Energy Systems (PEDES) & 2010 Power India, 2010 Joint International Conference on; 01/2011
  • P. Jayaprakash, Bhim Singh, D. P. Kothari
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    ABSTRACT: The proposed distribution static compensator is used to compensate the reactive power for power factor correction or voltage regulation along with load balancing, neutral current compensation, and harmonics current elimination. A zig-zag/star transformer is used to isolate the voltage source converter, and it is operated as a three-phase four-wire distribution static compensator for power quality improvement in a three-phase four-wire system. In order to reduce the current rating of the voltage source converter, the zig-zag configuration is used in the primary windings of the transformer. The voltage source converter is connected to the secondary windings of the zig-zag/star transformer, and this allows the optimum selection of voltage rating of the voltage source converter. Moreover, this transformer connection provides isolation for the voltage source converter system. The distribution static compensator is implemented using the dSPACE DS1104 R&D controller (dSPACE Inc., Wixom, Michigan, USA) and a slave digital signal processor subsystem based on the TMS320F240 digital signal processor (dSPACE Inc., Wixom, Michigan, USA) to validate the design and the developed control algorithm.
    Electric Power Components and Systems 01/2011; 39(1):15-30. · 0.62 Impact Factor
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    ABSTRACT: Market clearing price (MCP) has been the prime operating function for a pool operator in energy trading scenario. Its main objective is to maximize the social welfare function where the society i.e. both the generating companies and the consumers are benefited and unbiased. Many researchers take stepped bid functions of both the generators and consumers as inputs for determining MCP (λ). But owing to reason of having less information and less realistic, quadratic bidding functions are preferred and a closed form solution scheme with and without loss have been developed. Gradient technique has been used for finding the mcp when losses are considered. All the above solution has been interpreted using graphical approach. The proposed approach has been tested on a 30 bus system and a 3 unit system. From the results, a conceptual understanding has been made and how various market conditions have an impact on the MCP is discussed. The results obtained are quite encouraging and useful for the present context of deregulation and restructuring of electricity market. MATLAB 7.0 has been used to carry out the simulation.
    Utility Exhibition on Power and Energy Systems: Issues & Prospects for Asia (ICUE), 2011 International Conference and; 01/2011
  • Bhim Singh, P. Jayaprakash, D.P. Kothari
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    ABSTRACT: A large number of single-phase linear and non-linear loads may be supplied from three phase ac mains with neutral conductor. They cause excessive neutral current, harmonics and reactive power burden and unbalance. A four wire DSTATCOM (distribution static compensator) is used for neutral current compensation along with reactive power compensation, harmonics elimination and load balancing. A novel control approach is proposed for the control of four wire DSTATCOM under non-ideal supply voltage conditions. A four-leg voltage–source converter (VSC) with a dc capacitor is used as a four wire DSTATCOM. The proposed control approach is based on synchronous reference frame (SRF) theory and an indirect current control technique. The switching signals for the voltage–source converter (VSC) of the DSTATCOM are derived from the estimated reference supply currents. The load balancing, harmonics elimination and the neutral current compensation are demonstrated along with unity power factor (UPF) and zero voltage regulation (ZVR) modes of operation. Simulation results based on MATLAB software with its Simulink and power system blockset (PSB) toolboxes are presented to validate the control strategy. The DSTATCOM is able to maintain the self-supported dc bus under various disturbances.Highlights► DSTATCOM ensures sinusoidal source current at non-ideal supply voltage conditions. ► DSTATCOM is tested for power factor correction and voltage regulation mode. ► Synchronous reference frame theory is used for reference source current extraction. ► It works as harmonic filter, load balancer and neutral current compensator also.
    International Journal of Electrical Power & Energy Systems 01/2011; 33(5):1109-1117. · 3.43 Impact Factor
  • T. S. Bhatti, R. C. Bansal, D.P. Kothari
    01/2011;
  • R. C. Bansal, T. S. Bhatti, D.P. Kothari
    01/2011;
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    ABSTRACT: Load flow or power flow is the solution for the normal balanced steady-state operating conditions of an electric power system. It became an essential prerequisite for power system studies as it is used to ensure that electrical power transfer from generators to consumers through the grid system is stable, reliable and economic. In this paper, the topology based load flow studies are made available in the MATLAB -Graphical User Interface (GUI) environment which will bring the load flow studies more user friendly. Using this tool, extensive graphical analysis has also been made. Standard IEEE test systems are taken as an input data and the results are plotted. This can also be extended for any analysis where load flow results are used as an input.
    Sustainable Energy and Intelligent Systems (SEISCON 2011), International Conference on; 01/2011
  • L. D. Arya, L. S. Titare, D. P. Kothari
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    ABSTRACT: This paper describes a probabilistic approach for the adequacy assessment of a distribution system having distribution generator (DG) sets, which are owned and controlled by customers. Markov modeling has been employed to obtain capacity outage table for DG sets. Available capacity of distribution substation has been assumed as continuous random variable. Discrete capacity distribution is added to continuous distribution of substation capacity and merged with hourly peak load for obtaining probability of failure and expected demand not supplied (EDNS) annually with the help of derived closed form relations. The procedure has been illustrated with a case study.
    International Journal of Electrical Power & Energy Systems - INT J ELEC POWER ENERG SYST. 01/2011; 33(5):1161-1164.
  • P. Jayaprakash, B. Singh, D.P. Kothari
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    ABSTRACT: A three-phase four-wire DSTATCOM (distribution static compensator) based on three-leg VSC (voltage source converter) isolated with a star/hexagon transformer is demonstrated for power quality enhancement in a three-phase four-wire distribution system. The DSTATCOM is controlled to compensate the reactive power, eliminate harmonic currents, balances the load and also to mitigate the neutral current. The use of star/hexagon transformer for interfacing to a three-phase four-wire power distribution system reduces required rating of the VSC for a three-phase four-wire DSTATCOM. The IGBT (insulated gate bipolar transistor) based VSC is a capacitor supported and it is controlled for the required compensation of the load currents. The dc bus voltage of the VSC is regulated during varying load conditions. The control algorithm is based on the synchronous reference frame (SRF) theory for generating the gating pulses of VSC of DSTATCOM. The performance of the three-phase four-wire DSTATCOM is validated for power quality enhancement with linear loads as well as non-linear loads through hardware implementation using dSPACE, which is based on DS1104 R&D controller and a slave DSP subsystem based on TMS320F240.
    Emerging Trends in Engineering and Technology (ICETET), 2009 2nd International Conference on; 01/2010

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