Читать книгу Smart Solar PV Inverters with Advanced Grid Support Functionalities - Rajiv K. Varma - Страница 36

A significant adverse impact of solar PV systems is that their outputs are variable, and hence they are not dispatchable as conventional generators. Their power output can be frequently and substantially impacted by environmental conditions such as cloud coverage. In addition, an increasing amount of solar PV generation (e.g. rooftop) is not observable by the system operator, which creates challenges in maintaining system reliability with such large intermittent PV generation resources.

Some techniques for predicting and addressing the variability are presented below.

Techniques are continuously being developed to accurately predict the environmental conditions for both wind and PV‐based IBRs and DERs in very short intervals of time [50]. Solar PV power forecast reduces the uncertainty of the intermittency and variability of such power generation. This helps system operators to commit and decommit synchronous generators to handle situations of high and low power output from these renewable energy systems. The forecasts are also of great value in lowering the amount of operating reserves required for the system, thereby reducing the overall system operating cost.

The variability from solar power arises due to cloud passage. Short‐term cloud forecasting can be done by sky imaging which can predict approaching clouds. Forecasting in the time frame of next few hours can be based on satellite imagery of clouds. Longer‐term forecasting can be done on the basis of weather models to determine the formation of clouds [50].

Despite the gradual emergence of accurate forecasting, the power system must still respond and adapt to the changing power output from such IBRs and DERs so as not to impact system reliability and continuity of the power supply to customers.