جستجوی مقالات مرتبط با کلیدواژه « آلودگی » در نشریات گروه « برق »

High pressure insulators are exposed to different environmental and climatic conditions. The interaction of environmental conditions and insulation pollution makes the insulation of the insulators themselves a suitable substrate for conducting current and leaving its effects on power systems. Knowledge of potential distribution and electric field of high voltage equipment is an important aspect of the design, operation and performance of high pressure insulators. This can be useful for detecting defects in insulation. The purpose of this study is to show the behavior of contaminated insulators under voltage. Therefore, electric field simulation and potential distribution in the vicinity of different insulation levels were discussed. Insulators are modeled in two ways: 2D, 3D and Multiphysics Comsol software analysis, which is one of the best software used in modeling for finite elements. Finally, the results of potential distribution and electric field along the insulation in different contaminated and clean conditions, which are simulated using different conductivity values, are shown.

In this paper, the effect of surface charges and pollution on flashover voltage of polymeric insulators under DC voltage have been investigated and analyzed. For this purpose, four types of polymeric insulators with different profiles have been selected and then experimental tests of DC flashover voltage have been performed. According to the obtained results, with increasing pollution in presence of positive surface charges flashover voltage reduce, but negative charges increase it. Also in this paper, a model based on geometric parameters including specific leakage distance, shed spacing to shed depth ratio, amount of surface charges and pollution is proposed using an artificial neural network. The comparison of the obtained results from experimental tests and ANN model show that the results of ANN are consistent with experimental tests.

Polymeric insulators in overhead transmission lines are under different stresses such as: electrical, environmental and mechanical stresses. These factors cause the insulator aging and the increase of leakage current and also the decrease of flashover voltage. When layer of environmental pollutants is formed on the insulator surface and combined with atmospheric moisture, low impedance path created on the surface that prone to more leakage current and also less flashover voltage. This event makes the fault in the insulators especially in aged insulators. In this paper to investigate the effects of aging on the leakage current and flashover voltage of polymer insulators under contamination and humidity, four different types of 20 kV polymer insulators put inside the artificial aging chamber for 1,000 hours. Then every two weeks one of each type of insulators was removed from aging chamber and flashover voltages and leakage current signals were measured and the obtained results were evaluated. In addition for monitoring the insulator surface state at different stages of aging, scan electron microscopy (SEM) was conducted and the results show that aged insulators have more pores and with weaken hydrophobic properties, leading to poor performance of insulator and increase the leakage current and decrease the flashover voltage.

Distributed Hash Tables (DHTs) are used in the peer-to-peer networks for scalable and distributed localization of resources. However, malicious peers may affect the lookups by manipulating the routing information. Without any central monitoring nodes, pollution will be a real concern in these networks. In this paper, using the peer feedbacks about each other, a reputation system is formed. The proposed consensus algorithm assigns reputation scores to the peers of the system. By using consensus algorithm, the peers can aggregate on the reputation score of the desired peer and make a trust decision about it. The success rate of searches in the proposed consensus algorithm is 15% higher than the ReDS algorithm which is one of the best reputation systems based on DHTs that is designed against pollution in the peer to peer systems. In the following, the weighted consensus algorithm has been proposed. In the weighted consensus algorithm, the reputation scores suggested by other peers are weighted by their own reputation scores. In the weighted consensus algorithm, the success rate of the searches is approximately 40% increased while the memory usage is increased about 14% compared to the consensus algorithm.

Energy efficiency of power plants is less than 60% However, the efficiency of the CHP units can be up to 90 %.CHP units in addition to high efficiency, They reduce environmental pollutants by 13 to 18 percent. The purpose of this thesis is to use the simultaneous power and power generation plants to reach the optimal economic destination for Genco And to maximize economic profit And to minimize environmental releases based on the integration of CHP systems with conventional heat generating units on the power grid The Crow Search Optimization algorithm (CSA) is used to solve the economic load distribution problem (CHPED) And the problem of the economic load distribution (CHPEED) as well as the problem of economic load distribution with the participation of electricity services market in MATLAB software simulation and its results for all three modes are presented. The proposed method is used for ten power plants with different characteristics with variable load The results of the Csa approach for optimization based on comparison with the results of the Ant colony algorithm as well as other algorithms considered in other studies are valid. When the CHP units are integrated with the integrated system of 10 TG, the results of the implementation of the proposed approach are very promising.

The micro-turbines can be used to supply both thermal and electrical energy demands of islanded microgrid. Depleting fossil fuels and ever-increasing environmental concerns have attracted much attention to the renewable energy resources. Meanwhile, the stochastic nature, non-compliance with the load, inability to meet the thermal load and high cost of the wind and solar resources are disadvantages for them. In this paper, proposed microgrid includes a storage energy system, heater, micro-turbines and boiler, and is designed so that not only the mentioned problems could be solved but also the optimal size of renewable and non-renewable resources in the microgrid, for supplying electrical and thermal load, is determined. The renewable resources development strategies and optimal size for other resources is determined with using sensitivity analysis for fuel prices, pollution penalties and for government assistance in financing renewable resources. Modified Particles Swarm Optimization (MPSO) Algorithm is used to obtain global optimal solution. IEEE load as well as wind speed and solar radiation data, from the Ardabil region, have been used for our case study.

Depleting fossil fuels and ever-increasing environmental have attracted much attention to the renewable energy resources. The Micro-Grid (MG) concept is an appropriate means for increasing the adaptation of these resources with current power system architecture. In this paper a new method is used to solve the problem of unit sizing in a grid-connected MG providing electrical and thermal loads simultaneously. Our main goal is to reduce the fossil fuels dependency of the MG which includes a photovoltaic (PV)/ wind hybrid system with storage energy system including electrolyzer, hydrogen tank, CHP based fuel cell, heater and boiler. The heater is used as the provider of part of the thermal load when the generated power is more than the load and the capacity of the storage system is not adequate, and the boiler is used as backup unit for supplying thermal load. Due to high importance of the pollution problems, this subject is considered in objective function as cost term. Reliability index is used as limitative subject and interruption cost considered in the objective function. IEEE load data and real case study in Ardabil region for wind speed and solar radiation has been used. Modified Particles Swarm Optimization (MPSO) Algorithm is used to obtain global optimal solution.

Utilization of various types of fossil fuels will cause emission of greenhouse gases as well environmental pollutants. Thus, in the present investigation, in addition to the assessment of energy and environment aspects, policies for substitution of fossil fuels will be discussed. The results of present investigation revealed that elimination of subsidies and their chanalization can greatly improve environmental situation. The government of Iran can gain a lot through promotion of energy efficiency by minimal investment. Standardization of energy consumption by home appliances is among effective action for the reduction of energy use. In the long term, utilization of new renewable energy would be inevitable and therefore proper ground for research and development (R&D) must be drawn by Government.