Power quality assessment via physically based statistical simulation method

The quality of power at the consumer site is affected by: (a) temporary disturbances that may originate anywhere in the system; and (b) waveform distortion from nonlinear loads. The sources of disturbances are multiple and with varying parameters. For example, in many places of the world, the most frequent disturbances originate from lightning activity near electric installations. Lightning may result in flashover causing voltage sags to some portion of the distribution system, voltage swell to other areas, as well as interruption of power. The number of customers affected depends on the design of the system and placement of interruption devices, while the level of voltage sags or swells may depend on the grounding system, size of neutral, etc. These causes are statistically distributed both in time and in space. For meaningful assessment of their effects on power quality, a statistical method is proposed. The method is based on Monte Carlo simulation of the integrated utility system/customer system. The proposed integrated model is based on the physical design parameters of the system. This approach makes it possible to relate the design parameters of a system to the statistical power quality level of the system at the customer site. Thus the proposed model is very useful for meaningful improvements of the system to maximize power quality