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At oil transformer coils made by paper insulation, the present of water in paper lead to insulation demotion and electric faults. In the vat of transformers, at ambient temperature, the water migrates from oil in the isolation paper. The water in paper is distributed uniformly. At present times, for extracting the water from the isolate paper of coils conductors, with transformers in function, most...
We can observe in all electrical systems in the world, cc. 0.2,..., 0.35 Hz oscillations in state variables in steady state operation. The amplitude of these - so called inter-area oscillations - is growing going away from the centre of a large electrical power system. In the UCTE (European) system in the centre (near the German-French border) the amplitude of oscillations in frequency deviation time...
The safety of power networks is formulated in terms of probability, considering the failure processes as inherent stochastic events of large systems. This approach is important to design reliable power systems based on some optimal values for the system's availability and the involved costs. The vulnerability expressed visa the disturbances initiated by natural disasters, adverse weather, technical...
Reactive power must be measured and watched to verify accomplishment of Spanish grid code requirements in wind farms. However, no definition of reactive power is established in that code. Thus, two reactive power formulations are compared in this paper applied to wind farm generators in presence of transient disturbances such as voltage dips. First reactive power formulation is based on Emanuel's...
Techniques for locating a partial discharge source are of major importance in both the maintenance and repair of a transformer. This paper presents a novel approach to identify partial discharge locations in transformer winding using neural network. In this paper for simulation and detection of partial discharge, detail model of transformer is used. With modeling of partial discharge impulse source...
Knowledge of the short-circuit impedance variation is necessary for verifying the observance of the technical conditions (including the design conditions), certain nonconformities in the winding execution, checking the winding behavior in operation, verifying the system and short-circuit calculation (including the correct protection setup), the loading of the same type units, or more importantly,...
This report presents the results of investigations of active power variation influences on such parameter values of transients as voltage frequency at power supply networks and voltage phase at the same network. It was analyzed the main types of theoretical transfer functions and experimental ones for equivalent power system with thermoelectric power stations. Analyzed transfer functions correspond...
A basic component of the power quality generally and energy supply in particular is the management of maintenance actions of electric transmission and distribution networks. Starting from this fact, the paper develops a mathematical model of external interventions upon a system henceforth called Renewal Processes. These are performed in order to reestablish system performances i. e. its availability.
Papermaking industry has energy-intensive installations that consume high amounts of energy but at the same time produce steam and electrical power on site by use of regenerative fuels. Black liquor and bark result from the technological. These renewable sources usually are burnt to recover chemicals and energy. In this paper there is presented a methodology for evaluation of renewable use in the...
Traditional statistical reliability analysis relies on failure data for a population of devices. If a complete data set is available, statistical reliability analysis can provide predictions, such as mean-time-to-failure for a particular device, percentages of devices that will fail at a particular time or before a particular age, a statistical distribution of failure ages, and other statistical measures...
The paper deals with aspects related to the impact of connecting wind power plants to NPS, representing an important share in the total generated power, on the development of the new sources and transmission network. At the present moment there are installed not more than 10 MW in wind power plants but Romania faces a large number of connection request from wind power plant investors. Thus it is important...
There is a need to accurately determine expansion of transmission system to accommodate the connection of wind power in an efficient manner. The current transmission planning criteria in the UK was developed for systems with conventional generation and is not suitable for systems with high wind penetration. In this paper, a Cost-Benefit Analysis (CBA) based transmission expansion problem is described...
In this study, the aim is to detect an induction motor's winding faults by using independent component analysis (ICA). Many laboratory experiments have been done on an induction motor to check the performance of the proposed method. The phase currents of the induction motor are used in the fault detection algorithm. The algorithm is implemente d by using MATLAB. The proposed method is compared to...
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