Conventional Ratio and Artificial Intelligence (AI) Diagnostic methods for DGA in Electrical Transformers

AuthorsAmin Samy, Sayed A. Ward,  Mahmud N. Ali

 

Abstract

Transformers are always under the impact of electrical, mechanical, thermal and environmental stresses that degrade their insulation quality. To avoid the power failure, periodical monitoring of the conditions of transformers is necessary. Results of early detection of fault can provide large savings in operation and maintenance costs and preventing any premature breakdown/failure. In this paper the DGA (dissolved gas analysis) is studied and the different diagnosis methods are discussed. The conventional ratio methods and the artificial intelligence (AI) Diagnostic methods for DGA in electrical transformers are presented. A comparison between the two different diagnoses methods for a certain transformers already existed in the Egyptian electrical network is presented. These results are also compared to the results received from the central laboratories of the ministry of electricity in Egypt. The simulated results show that the ratio of matched results from the artificial intelligence diagnostic methods (using neural network) was higher than the ratio of matched results from the conventional ratio methods.

 

Index Terms

Dissolved gas analysis, DGA, conventional ratio methods, artificial neural network

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Conventional Ratio and Artificial Intelligence (AI) Diagnostic methods for DGA in  Electrical Transformers

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Adaptive Network Protection Strategy for Microgrid

  Authors:  Khaled M. Sedik, Amr M. Abdin,   Almoataz Y. Abdelaziz

Abstract

Microgrid (MG) can provide quality and reliable supply of energy to consumer. Operating in both modes, grid connected mode and islanded mode. The complexity of protection scheme occurs when protective devices cannot recognize the change of the fault current when the system is working in grid connected mode or in islanded mode. This paper presents an adaptive over current protection system which automatically amends the protection settings of all over current relays in response to the impact of DG. The methodology takes into account typical protection schemes, protection requirements, protections coordination and distributed generation impact on protection system the proposed adaptive network protection scheme is applied on IEEE 13 nodes radial distribution test feeder, to study the impact of distributed generation on the protection system and to prove the proposed design methodology.

Index Terms

 Adaptive over current protection, Distributed Generation impact, protection coordination

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Adaptive Network Protection Strategy for Microgrid

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A New Method for Optimal Coordination of Overcurrent Relays in Power System Networks

Abstract

Short circuit conditions can occur unexpectedly in any part of a power system at any time due to various physical problems. Such situations cause a large amount of fault current flow through some power system apparatus. The occurrence of the fault is harmful and must be isolated promptly by a set of protective devices. The duty of protective systems is the timely detection of fault and removing it from the power network. One of the most important protective elements that are used in power networks are overcurrent relays. In this article, a new algorithm is presented to solve the optimization problem of coordination of overcurrent relays by using Cuckoo Optimization Algorithm which considers the non-linear model overcurrent relays at all stages of setting. The results show that the proposed approach can be provide more effective and practical solutions to minimize the time function of the relays and achieving optimal coordination in comparison with previous studies on optimal coordination of overcurrent relays in power system networks. The proposed method is tested on IEEE 8-bus standard network. Also the results obtained have been compared with other evolutionary algorithms.

Index Terms

Cuckoo Optimization Algorithm (COA), Optimal coordination of relays, Overcurrent relay, Optimization methods

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A New Method for Optimal Coordination of Overcurrent Relays in Power System Networks

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A Comprehensive Investigation of Introducing an Innovative Hybrid Non-Dominated Sorting Differential Evolutionary Algorithm

AuthorsMohammad Bakhshipour, Farhad Namdari, Mohammad Sedaghat, Neda karimi

Abstract

This paper presents a new multi objective optimization algorithm with the aim of complete coverage, faster global convergence and higher solution quality. In this technique, the high-speed characteristic of particle swarm optimization (PSO) algorithm is combined with non-dominated sorting differential evolutionary (NSDE) method and an efficient hybrid multi objective optimization algorithm is created. This approach possesses high convergence characteristics in quite less execution times. Generating fewer populations to find the pareto front also makes the proposed algorithm use less memory. For the purpose of performance evaluation, the algorithm is verified with four benchmarking functions on its global optimal search ability and compared with two recognized algorithm to assess its diversity.

Index Terms

Hybrid multi objective optimization algorithm, Particle swarm optimization (PSO), non-dominated sorting differential evolutionary (NSDE), Benchmark Study

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A Comprehensive Investigation of Introducing an Innovative Hybrid Non-Dominated Sorting Differential Evolutionary Algorithm 

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Identification of Rotor Bar Fault in Induction Motor in Presence of PQ Disturbances Using FFT-DWT Based Integrated Neural Network

AuthorsSridhar. S , K. Uma Rao  , Sukrutha Jade

Abstract

This paper presents a methodology for the detection of broken rotor bar fault in induction motor in presence of power quality (PQ) disturbances. Stator current of phase A is sampled with a sampling frequency of 100KHz. Fast Fourier Transforms (FFT) and discrete wavelet transform (DWT) are applied to the stator current and the corresponding coefficients are extracted. These coefficients are fed as inputs to feedforward neural networks. Two stage neural network is used for obtaining better classification and quantification accuracy. The output of the neural network classifies the health of the rotor of the induction motor (healthy/ faulty), and also the nature of the supply. The entire simulation is carried out using MATLAB. The proposed network has performance efficiency of 97.3%. It is observed that though wavelet coefficients alone give good results during classification, its accuracy is just satisfactory during quantification. Further FFT and wavelet coefficients together are found to give good results during quantification.

Index terms

Artificial neural network, Discrete wavelet transforms, rotor bar fault, Induction motor, fault detection and prognosis, fast fourier transforms.

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Identification of Rotor Bar Fault in Induction Motor in Presence of PQ Disturbances Using FFT-DWT Based Integrated Neural Network

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Power System Observability of Phasor Measurement Units: A Binary Integer programming Approach

AuthorsAhmed Hamdy Ghazy Ibrahim, Said Fouad Mekhamer, Walid A. Omran

 

Abstract

In this paper, the allocation problem of Phasor measurement units (PMU) is solved using a binary integer programming (BIP) method. The proposed approach aims to minimize the total number of PMUs that can achieve full system observability. Defining N as the number of system buses, the full system observability is ensured both in normal operating conditions and in case of N-1 contingencies such as the outage of a PMU or a transmission line. Moreover, the approach is utilized to allocate the PMUs in case of limited number of PMU channels. The problem formulation considers the Zero Injection Buses (ZIBs) and uses a set of rules that can improve the redundancy of the PMUs by choosing better locations without increasing their number. The proposed approach is applied to the IEEE standard systems 14, 30 and 57 test systems. The simulations results are compared with other approaches used in the literature to validate the effective performance of the proposed approach.

Index Terms

 Binary Integer programming, observability, optimal placement, phasor measurement units, channel limitation

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Power System Observability of Phasor Measurement Units: A Binary Integer programming Approach

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A Novel Protection Methodology for Distribution Systems Equipped with Distributed Generation

AuthorsA.F. Naiem, Y. Hegazy, A. Y. Abdelaziz, A. Elsharkawy


Abstract

In this paper, a new strategy is proposed to provide a solution to the recloser-fuse coordination problem that appears after distributed generation penetration in distribution systems. The core of this strategy is based on classifying the coordination status at fault conditions to either coordination holds or coordination lost. The main benefit from this classification process is to indicate if the existing protection scheme can deal with the fault or an additional action is required. Three different actions are then proposed in this strategy to decrease the cases where coordination is lost. The first is based on searching for the best DG location, while the second is based on changing the recloser characteristics and the last one is based on preparing information about which DG when disconnected, the protection coordination can be re-attained. The proposed strategy is evaluated by being implemented to the IEEE 34-node test feeder. The obtained results show the ability of the classification process to discriminate between the cases where coordination holds and those where coordination is lost. Moreover a considerable decrease in the cases classified as coordination lost after applying the proposed solutions is achieved. All the required software is developed by the authors using MATLAB m-files as a platform.

 

Index Terms

Recloser-fuse coordination, Distributed Generation, Distribution Systems

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A Novel Protection Methodology for Distribution Systems Equipped with Distributed Generation

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Multiobjective Optimal Reconfiguration of Power Distribution Systems with Load Uncertainty Using a Genetic Algorithm Based on NSGA-II

AuthorsSina Khajeh Ahmad Attari, Mahmoud Reza Shakarami, Farhad Namdari, Mohammad Bakhshipour


Abstract

Reconfiguration, by exchanging the functional links between the elements of the system, represents one of the most important measures which can improve the operational performance of a distribution system. Various criteria are taken into account to solve the reconfiguration of distribution systems. The criteria for optimization are evaluated on active power distribution systems. The novelty of the method consists in: the criteria for optimization are evaluated on active power distribution systems; the original formulation (Pareto optimality) of the optimization problem and an original genetic algorithm (based on NSGA-II) to solve the problem in a non-prohibitive execution time. For load uncertainty the probabilistic distribution-based interval arithmetic approach is used to incorporate uncertainty in load demand that can forecast reasonably accurate operational conditions of radial system distribution (RDS) with better computational efficiency. To verify the efficiency of proposed method, it has been conducted to IEEE 33-bus radial distribution system. Results have demonstrated the accuracy of the proposed algorithm.

Index Terms

Reconfiguration, Load uncertainty, Genetic algorithms, Multi-objective optimization, Pareto optimality, Power distribution systems

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Multiobjective Optimal Reconfiguration of Power Distribution Systems with Load Uncertainty Using a Genetic Algorithm Based on NSGA-II

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A REVIEW: Control Techniques for Shunt Active Power Filter for Power Quality Improvement from Non-Linear Loads

 AuthorsSeemant Chourasiya, Seema Agarwal


Abstract

It is the era of Digital World and this is possible only by the extensive use of electronic and power electronic devices. At the present time maximum electrical loads are non linear in nature. So they are very good for the use of human being but harmful to the “Power Quality”. Power should be in the prescribed limitation (International Standards) but because of non linear loads power is not bound in limitations and distorted. So Harmonics are Present and need to be mitigating to improve the performance of the loads. Both voltage and current harmonics are distorted but current harmonics are very common and give adverse effect on economical utilities of customers so that to mitigate shunt active power filter is used. Here in this paper a technical review on Control strategies to inject compensating current and different Techniques to generate the Pulse for Shunt Active Power Filter (DC link- Inverter).

Index Terms

 Shunt active power filter, Current reference theory, PQ theory, DC voltage balancing, PI controller, Fuzzy logic controller

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A REVIEW: Control Techniques for Shunt Active Power Filter for Power Quality Improvement from Non-Linear Loads

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Impact of Security Constraints on Electricity Market Economics

Authors: Varaprasad Janamala

Abstract
In the present pace of power system deregulation, transmission system is playing a key role in electricity market settlement. The inability of transmission system to dispatch market driven schedule is known as congestion and which is not desirable for successful operation. The economic efficiency is mainly dependent on transmission system support and there is a need to understand the impact of security constraints on market clearing process. This work considered (N-1) line outage contingency as a security constraint and imposed on pool based electricity market settlement. The analysis is done on a simple three bus network and the results validating the need of transmission system expansion/upgradation to avoid market economic inefficiency.

Index Terms

Congestion, Deregulation, Pool market settlement, Redispatch

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Impact of Security Constraints on Electricity Market Economics  

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