The integration of renewable energy sources into the power grid and the extension of power transfer capabilities is one important step towards a reduction in CO2 emissions, a sustainable infrastructure and power generation. In the electric grid this is causing a shift from the centralized generation of energy by big rotating AC generators towards more complicated, distributed, often semiconductor-based grid components using DC Power in the process of power generation and often higher system voltages. The latter is underlined by the trend of ultra high voltage (UHV) power transmission This leads to the need of more adequate, adapted test principles for the examination of the capabilities of grid components. In this context the work on the next revision of the standard IEC 60060 considers the implementation of combined and composite voltages for impulse voltage tests. Until now there is no uniform procedure for the evaluation of the parameters of these novel test voltages, in particular for the case of more complex composite waveshapes. One Example would be an Impulse superimposed to a 50 Hz AC signal which record does not cover a whole period. In this paper we would like to investigate approaches in how to obtain concise and comparable results when working with combined and composite test voltages. These voltages consist out of Lightning Impulses (LI) or Switching Impulses (SI) superimposed to a conventional power supply voltage that is either an AC or a DC Voltage. For the evaluation of the parameters, it is often necessary to separate the supply voltage from the transient impulse. Especially when working with Impulses superimposed to an AC voltage the task of separating is not trivial and can affect the results. For this task there are several approaches that can be considered and, of course, deliver results of different quality. In this paper we describe and investigate our work on the development on a evaluation method of composite voltages consisting of AC and impulses using a numerical regression.

evaluation,impulse voltage,composite,combined,lightning impluse