Lajos Jozsa

Infrared Thermography in Energy Audit of Electrical Installations

Subject review Energy Audit of Electrical Installations is an integral part of the overall energy audit of complex technical systems, and infrared thermography is one of the non-destructive testing (NDT) methods for that type of analysis of power distribution subsystems. During the energy audit of the power subsystem by means of a thermal camera, it is necessary to carry out some additional measurements of electrical quantities which are often not performed easily. The paper provides an overview of the standards in the field of thermography and safety criteria of electrical installations based on a thermal image and measured electrical parameters. As a practical example, an analysis of an electric power distribution subsystem of large complex industrial consumers is presented.The procedure of the audit and decision making for future maintenance is described in detail. Recommendations of corrective actions in the maintenance procedure based on the absolute temperature criterion and the delta-T criterion under consideration of the measured load are given as well.

The application of fuzzy inference systems in overload elimination and correction

The paper deals with analysis of the safety and stability of a power supply network. In the modern market the need for power system to function near stability margin is increased, and also very close to the permissible limits of thermal limitations of the transmission power system. The known methods for analyses have slow convergence or inadequate accuracy. A fuzzy logic regulator makes the needed adjustments and uses fuzzy inference systems that are based on the settings embedded on knowledge and experience of experts. The basic idea is to develop a fuzzy logic system that will be based on the vulnerability indices of the systems components, and together with the overload factor, represents the input values suitable to control processes. Another goal is the creation of the controller that will allow more efficient way of power system operation by using the safety analysis to eliminate line overloads.

Use of Fuzzy Logic Systems for Assessment of Primary Faults

Abstract In electric power systems, grid elements are often subjected to very complex and demanding disturbances or dangerous operating conditions. Determining initial fault or cause of those states is a difficult task. When fault occurs, often it is an imperative to disconnect affected grid element from the grid. This paper contains an overview of possibilities for using fuzzy logic in an assessment of primary faults in the transmission grid. The tool for this task is SCADA system, which is based on information of currents, voltages, events of protection devices and status of circuit breakers in the grid. The function model described with the membership function and fuzzy logic systems will be presented in the paper. For input data, diagnostics system uses information of protection devices tripping, states of circuit breakers and measurements of currents and voltages before and after faults.