1,721,121 research outputs found
Radial Power Flow Tolerance Analysis by Interval Constraint Propagation
No full textMany applications in modern distribution management systems (DMS) need the support of robust and reliable radial power flow analysis. In this connection, although radial power flow solution algorithms are widely proposed in the literature, their application is often complicated by the presence of uncertainties affecting the distribution network operation. The effect of these uncertainties could affect the power flow solution to a considerable extent. A comprehensive tolerance analysis is therefore required in order to incorporate the effect of data uncertainties into power flow analysis. To address this problem, in this paper the employment of interval constraint propagation (ICP) is proposed. ICP is an effective technique for refining enclosures to solutions of nonlinear systems of equations by merging interval mathematic and constraint propagation techniques. Several numerical results are presented and discussed in order to assess the effectiveness of the proposed methodology as an alternative to sampling-based technique, in radial power flow analysis
An Adaptive Smart Sensor Network for Overhead Lines Thermal Rating Prediction
No full textThe need for dynamic loading of overhead lines requires reliable assessment tools that should
be able to predict both the evolution of the hot-spot temperature and the associated maximum
allowed duration, at any load level and on the basis of the actual conductor thermal state and
environmental conditions. In order to address this problem, the paper proposes the employment of
a smart sensor network distributed along the line route. Each network’s node, starting from on-line
measurements, assesses, by an indirect method of parameter identification, the value of the main
variables which regulate the heat exchange between the conductor and its surrounding. Then,
starting from these data, each node calculates the load capability curve by solving iteratively a
built in dynamic thermal model and transmits the results to a central server by a cooperative based
communication paradigm. To assess the performances of the proposed solution, experimental
studies obtained on a laboratory overhead line are presented and discussed
Transient tolerance analysis of power cables thermal dynamic by interval mathematic
No full textThe safeguard of power equipments is assuming a major role in the deregulated electricity market, where a malfunctioning power system could
be responsible for serious damages to a large number of system operators having access to the shared energy resource.
In this context thermal monitoring of power cables represents a key issue in evaluating the risks associated with a given load management policy
especially during emergency conditions. In particular this demands for reliable assessment models that should be able to predict the transient
thermal behaviour when the load exceeds the nameplate value.
In this connection the application of both simplified and detailed power cable thermal models is often complicated by the presence of uncertainties
affecting the tolerances of the input data. The effect of these uncertainties could influence the final solution to a considerable extent.
A comprehensive tolerance analysis is therefore required in order to incorporate the effect of data uncertainties into the thermal modelling
process.
To address this problem, in the paper the employment of interval mathematic is proposed. Several numerical results are presented and discussed
in order to assess the effectiveness of the proposed methodology which offer a rough qualitative insight of the solution in a very short time,
comparable to the time required for a deterministic numerical simulation
An Interval Computation Approach for Power Components Overload Protection in the presence of Data Uncertainty
No full textThe embedding of microprocessor-based relays in power
components enables improved overload protection because of higher
computational resources, adaptiveness and flexibility. The increased computing
power that is now embedded in power component devices makes possible the
real-time simulation of built-in thermal models. However, the use of
model-based protective systems is exposed to the uncertainty affecting some
model components. The effect of these uncertainties could compromise the
overall protective function reliability. To address this problem, we use Affine
Arithmetic (AA). In particular, AA can be used to calculate the component’s
hot spot temperature by solving a thermal dynamic model where parameters are
imprecise, and the uncertainty is represented by affine forms. The proposed
solution method is implemented on a microcontroller-based unit to develop a
prototype thermal relay equipped with robust tools for uncertainty data
management. Various experimental results are presented and discussed
Study of flashover phenomena on polluted insulation theoretical models and experimentation
No full textThe appreciable number of flashover of polluted insulators, energised with DC voltage, has motivated both theoretical and experimental studies for better understanding of the flashover processes. In order to study these phenomena different mathematical models for pollution flashover have been developed. These include models for sustaining DC arcs on contaminated surfaces, criteria for DC are motion as well as arc reignition models for contaminated AC insulators. The results have permitted to improve the characteristics of the materials and the design techniques employed to realise insulation components. Nevertheless, a lot of problems due to environmental pollution phenomena are not clear sufficiently yet. Typical examples are represented by ignition and propagation phenomena due to difficulties to identity all the parameters involved in pre-discharge and discharge phases. On the other hand, settingup accurate models for the different discharge phases can not always utilise a dedicated experimental validation. In order to obtain more general models, in the paper a partial validation method of analytical discharge models was proposed. The method consider a low number of parameters controllable and reproducible in laboratory tests. In order to validate the method, experimental results are compared with analytical simulations obtained by use of dynamic arc modeling capable to take into account the configuration of an insulator profile at every instant, which plays an important role in the flashover process
Fuzzy logic based optimal power flow management in Hybrid Electric Vehicles
No full textParallel Hybrid Electric Vehicle powertrain (PHEV), combining an electric motor with an auxiliary power unit, improves vehicle performance and fuel economy, reducing the effects of private cars on air quality in cities. These advantages can be enhanced by using a dedicated control strategy to identify the optimal power flow distribution at each instant of time in the main powerdrive sources as a function of the state of the powerdrive components and the actual driving conditions. In this connection the literature analysis has evidenced as the research efforts in the field of PHEV optimal power flow management should be oriented not only to develop precise and robust control strategies that can improve the vehicle performances, but also to lower the required computational resources making the solution strategy suitable with the vehicle dynamics and allowing, moreover, a cost effective hardware implementation. To develop this complex activity, fuzzy logic (FL) was used. As demonstrated by the simulation studies developed, FL enables the optimal power flow management problem to be solved by handling its intrinsic non-linearity using rules, membership functions, and the inference process. This results in improved performance, simpler implementation, and reduced design costs compared with rigorous mathematics based approaches
- …
