Niraj Kumar Choudhary

Protection coordination of over current relays in distribution system with DG and superconducting fault current limiter

This paper proposes the use of Superconducting fault current limiter (SFCL), in conjunction with directional over current relays (OCRs) to solve the protection coordination problem in distribution systems equipped with distributed Generator (DG). The SFCL size and optimal directional OCR settings are determined in the grid connected mode. The proposed approach is tested on the IEEE 34 node distribution system in which 26 OCRs are placed. On the occurrence of fault, level of fault current changes which in turn changes the operating time of various OCRs. Therefore, it is important to calculate and suggest method of the relay setting in order to minimize the operating time of relays and also to avoid the mal-operation. SFCL reduces the magnitude of short circuit current on the occurrence of fault and ultimately retains the coordination among various directional over current relays.

A review of power management and stability issues in microgrid

Demand of power is growing day by day but non-conventional sources which are primary sources of energy are not only limited but also the pollutants released from them cause pollution. Microgrid system is one of the best solutions of feeding electrical demand and checking pollution as most of the distributed energy resources (DER) used in the microgrid are environment friendly. Microgrid also maintains reliability of electricity in the system. Use of renewable generators like photo voltaic (PV), wind etc. provide power using conventional sources with less pollution, but their implementation in grid causes several complications like circulating current, voltage harmonics, reduction in storage life, over voltage and over current in transient etc. Apart from that other challenges like active-reactive power sharing, current sharing, power management among renewable sources and high penetration of renewable energy are required to be focused to increase the handling and working capability of microgrid. The paper proposes an extensive literature survey on these severe problems in microgrid system and enlists the different work going on to eliminate the particular type of problems.

Model Order Reduction Using Fuzzy C-Means Clustering and Particle Swarm Optimization

The hybrid method which combines the evolutionary programming technique, i.e., based on the swarm optimization algorithm and fuzzy c-means clustering method is used for reducing the model order of high-order linear time-invariant systems in the presented work. The process of clustering is used for finding the group of objects with similar nature that can be differentiated from the other dissimilar objects. The reduction of the numerator of original high-order model is done using the particle swarm optimization algorithm, and fuzzy c-means clustering technique is used for reducing the denominator of the higher-order model. The stability of the model is also verified using the pole zero stability analysis, and it was found that the obtained reduced-order model is stable. Further, the transient and steady state response of the obtained lower-order model as compared to the other existing techniques are better. The output of the obtained lower-order model is also compared with the other existing techniques in the literature in terms of ISE, ITSE, IAE, and ITAE.

Model order reduction using factor division algorithm and fuzzy c-means clustering technique

This paper proposes a novel hybrid approach that combines factor division algorithm and fuzzy c-means clustering technique for reducing the model order of high-order linear time invariant system. The process of clustering is used for finding the group of objects with similar nature that can be differentiated from the other dissimilar objects. The numerator of the higher order model is reduced using the factor division algorithm and the denominator of the higher order model is reduced using the fuzzy c-means clustering technique. The stability of the model is also verified using the pole zero stability analysis and it was found that the obtained reduced order model (ROM) is stable. Further, the steady state and transient response of the ROM is found to be better than the other existing techniques. The performance of the ROM is compared to other existing techniques in terms of integral square error, integral of time multiply squared error, integral absolute error and integral time-weighted absolute error.

Power Management in Microgrid: Analysis in Grid Connected and Islanded Mode of Operation

This paper presents an investigation about the impact of integrating renewable energy based generation sources on the existing distribution system in terms of load sharing. The study of load sharing among various distributed generators (DGs) and utility grid has been performed for two cases: (a) when equivalent source based DG is connected and (b) when real PV/Fuel cell based DG is properly integrated to the distribution system. The real photovoltaic and fuel cell based DG do not behave as stiff current/voltage source due to disturbances happening either internally in system known as parametric uncertainties or due to external disturbances like weather conditions, load change etc. Further it has been observed with extensive analysis using simulation result, that even though all DGs are of equal capacity in their generation but when the load is either increased or decreased this doesn’t essentially guarantee that all DGs will equally share the active and reactive power demand Full Text: PDF DOI: http://dx.doi.org/10.11591/ijape.v6.i3.pp163-173

Impact of distributed generation on coordination of overcurrent relays in a benchmark distribution system

The process of defining settings among various protective devices such that these devices operate in a specified order on the occurrence of any undesired fault in the system is known as protection coordination. This paper presents an analysis of coordination among various overcurrent relays (OCRs) in a benchmark system with the connection of distributed generators (DGs) at different locations. In the first case only one DG is integrated to the distribution system and the coordination characteristics has been calculated for various overcurrent relays in the system. Whereas in the second case two DG is connected at suitable locations to find out the coordination characteristics of OCRs installed in the distribution system. The objective function (OF), which is a function of time multiplier setting (TMS), is formulated for each case. The prime objective of this paper is to demonstrate a comparative study of protection coordination among various OCRs using different optimization techniques. In this paper genetic algorithm (GA), particle swarm optimization (PSO) and gravitational search algorithm (GSA) has been used for the optimization of TMS and total operating time of the relays. All the studies have been performed on IEEE-34 node benchmark distribution system which is simulated in MATLAB.

A novel approach of load sharing and busbar voltage regulation using Busbar voltage stabilizing controller in autonomous DC Microgrid

DC Microgrids have attained popularity these days due to its high reliability and easy interconnection with renewable Distributed energy resources (DERs). Inspect of all these advantages; interconnection of microgrid causes several issues like power sharing problem; voltage regulation errors; harmonics; circulating current etc which must be tackle down for seamless operation of microgrid. This paper took load sharing problem and voltage steady state error (ess) into consideration. Combination of two controllers namely P/V droop controller and Busbar voltage stabilizing controller (BVSC) is explained in autonomous DC microgrid. Using P/V droop controller; efficient load sharing among the converters with respect to their KVA rating is established. This controller however cause droop in voltage level of Busbar. To remove voltage droop due to increased power demand BVSC controller is used which is augmented with PID controller. It is justified in our analysis that proper selection of Vset point; integral (Ki); differential (Kd) and proportional (Kp) constant of BVSC eliminates the load sharing and high voltage regulation problem in DC microgrid.