System and method for power system parameter measurement

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#For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

#FIG. 1 is a block diagram of a test set according to an embodiment of the disclosure.

#FIG. 2A is an illustration of a dissipation factor versus frequency data set according to an embodiment of the disclosure.

#It should be understood at the outset that although illustrative implementations of one or more embodiments are illustrated below, the disclosed systems and methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, but may be modified within the scope of the appended claims along with their full scope of equivalents.

#The dissipation factor (DF) and/or insulation power factor of an electrical power system component is a measure of insulator loss-rate of power. In some contexts the insulation power factor may be referred to as the dissipation factor of the insulation of an electrical power system component. The electric power lost in a power system component is primarily lost in the form of heat. It is desirable to keep insulation power factor at a low level in power system components to avoid waste and to operate at maximum efficiency. Additionally, it is important to keep insulation power factor at a low level to avoid excessive heat in the power system components which may prematurely degrade and/or destroy the power system components. In extreme cases, excessively high insulation power factor may cause thermal runaway. The dissipation factor may be determined as the loss tangent as the ratio of the resistance to the reactance of the power system component: Tan δ=dissipation factor=R/X where R represents resistance and X represents the reactance of the power system component. The related insulation power factor may be determined as the ratio of the resistance to the amplitude of the impedance of the power system component: insulation power factor=R/{SQRT(SQR(R)+SQR(X))} It can readily be appreciated that for small values of dissipation factor, the dissipation factor is approximately equivalent to the insulation power factor. Insulation power factor may change with the temperature of the power system component, typically increasing at higher temperatures. Additionally, insulation power factor may change with aging of the power system component, for example as insulation materials degrade over time, typically increasing with age. The insulation power factor may change as a result of excessive moisture, for example a moisture content in a bushing or a moisture content in insulation of a transformer winding. When a power system component is new, the insulation power factor typically does not change significantly with increased temperatures. With increased age, however, the insulation power factor often changes more with increased temperature.

#Manufacturers of electrical power distribution transformers and bushings may provide data representing the insulation power factor of their components at different operating temperatures. This data, however, typically applies to new components. After components have been in operation for a period of time, the materials begin to break down and the insulation power factor can no longer be assumed to follow the data provided by the manufacturers. The procedure is to determine, such as by testing, the insulation power factor of the component at a plurality of different operating temperatures that may be experienced in a production environment, for example to determine insulation power factor at each of 20° C., 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., and 70° C. The resultant information can then be used to predict insulation power factor during day-to-day operation at different operating temperatures. If the insulation power factor is excessive, it is recommended that the power system component be taken out of service and maintained, for example refurbishing the component or decommissioning the component. Performing this kind of controlled temperature test for electrical power system components, however, is very difficult if not impracticable.