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200 Hybrid-Renewable Energy Systems in Microgrids

switching of DSM enabled loads causes frequent unintentional tripping of sensitive
equipment, and (4) the economic pricing may attract the simultaneous switching of
large number of loads leading to transient conditions [28,29].

4 New power quality indices

New PQ indices and standards need to be introduced for analyzing and regulating the
PQ phenomenon [18]. The novel PQ indices based on wavelet packet transform for
nonstationary sinusoidal and nonsinusoidal disturbances are given in Ref. [30]. This
includes methods to quantify emissions in the frequency range from 2 to 150 kHz,
and methods to quantify number and severity of voltage steps. New PQ indices are
also needed to quantify the voltage quality during islanded operation of AC/DC mi-
crogrids, during the transitions between islanded and grid connected operation, and
during feeder reconfiguration after a fault.

5 Conclusion

The adverse consequences on PQ due to smart grids are discussed in this chapter.
Improved PQ is one of the crucial aspect of the future electricity network and this can
be greatly achieved through the implementation of smart grids. Although the areas
where the research need to be focused in improving and maintain the reliability of
the grid when implementing smart grid is focused in this chapter. The adverse effects
due to the incorporation of microgrids, Distributed Generation and DSM schemes are
discussed in this chapter. The need for new PQ indices considering the implemen-
tation of smart grids in the near future is also stated. The growing use of sensitive
power electronic equipment by the consumers and the evolution of electric vehicles
have brought the need for discussion and knowledge on the PQ of smart grids very
essential.

References

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