Ferdowsi University of Mashhad

About: Ferdowsi University of Mashhad is a education organization based out in Mashhad, Iran. It is known for research contribution in the topics: Population & Catalysis. The organization has 11407 authors who have published 20810 publications receiving 263263 citations.

Comparison Between Communication Infrastructures of Centralized and Decentralized Wide Area Measurement Systems

Abstract: Restructuring in power systems has introduced new complexities and difficulties in controlling of these systems. Therefore, new control strategies should be investigated in operation of power systems. On the other hand, communication infrastructure (CI) is responsible for establishing any control strategy. The purposes of this study are twofold: firstly, to design a communication infrastructure for any given power network with determined measurements; secondly, to compare communication infrastructures for centralized and decentralized control strategies in power grids. The comparison criteria are communication network cost, delay (latency), and reliability. In this study, hybrid state estimation (HSE), as one of the most important wide area measurement systems (WAMS), is opted. Communication infrastructures are designed for two different control strategies; centralized and decentralized (multi-area) HSE. These strategies have been investigated in IEEE 118-bus test network. Some new concepts, that help us to compare any two given communication infrastructures with each other, are introduced. Finally, two designed communication infrastructures for these two strategies are compared with each other. The results show that, although communication infrastructure investments are almost the same in both cases, decentralizing, as a cause of decentralized control strategy, results in improvement of latency and reliability of CI.

Heat transfer and rheological properties of transformer oil-oxidized MWCNT nanofluid

Abstract: Power transformers play a key role in power and electrical industries and thus boosting their efficiency is necessary. In this study, the effect of oxidized multi-walled carbon nanotubes on transformer oil thermophysical properties was experimentally investigated. The maximum amount of carbon nanotubes was chosen up to 0.01 mass% to assure the maximum purity of transformer oil. Heat transfer characteristics of transformer oil and nanofluids in two cases of free and forced convection were studied. Breakdown voltage, flash point, pour point, density, electrical and thermal conductivities, viscosity and shear stress, as eight important quality parameters, were determined. According to the experimental results, the Breakdown voltage decreased through concentration increasing. Electrical conductivity is not changed considerable with increasing concentration and temperature. Thermal conductivity of nanofluids and transformer oil changed with increasing temperature and concentration. Furthermore, at all concentrations and temperatures, the viscosity of the nanofluids was lower than that of transformer oil.