Archivo para enero 28th, 2016


Optimum DG Penetration for Minimum Interruption Frequency

One question that most system operators are concerned with is the optimised DG penetration level. Relationship regarding different cost models between optimum DG penetration level and interruption frequency is indicated in Figure.

Optimum micro-source penetration level is positive related with the interruption frequency without DG penetration; especially for average interruption costs, the relationship is almost linear. This relationship is important for systemplanning; as the system interruption frequency without DG penetration is generally known, the system operator is able to roughly determine of the optimum DG penetration level from reliability point of view

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System unavailability comparison of different countries EU

A reduction of system unavailability Q, as one example for system reliability indices, by the installation of micro-sources that enable (partial) island operation is demonstrated in Figure for selected European countries, compared to the case without DG.

The countries which have worse system reliability achieve higher improvements than the countries with high system reliabilities also in case without DG. For instance, in Portugal rural network the system unavailability decreases from more than 10 h/a to the value of below 1 h/a with maximum and average cost model; even with average cost model yearly unavailability is also reduced to approximate 4h/a. However, the improvement for German urban network and Holland network, which have already good system reliability without micro-sources, is not obvious, although system reliability is also improved to a certain extent in both networks. With higher interruption cost model, system reliability can be better improved. Higher interruption costs justify higher micro-source investment, thus achieving higher system reliability improvements.  Microgrid operation from reliability point of view is thus most beneficial in countries with lower power quality or in regions or for customer segments with comparably high outage costs.

Source:
Christine Schwaegerl. “DG3&DG4 Report on the technical, social, economic, and environmental benefits provided by Microgrids on power system operation”. Siemens AG. 2009


Economic Benefit Comparison of Microgrids on European Level

The figure compares the maximum economic benefits of different networks with x-axis as the multiplication of the total load of the network and the unavailability of this network in each year, which is symbolized by PQ. Benefits ineach country are almost linear related with PQ as interruption costs without DG increase with increasing total demand and unavailability, leading to higher benefits of Microgrid operation. The higher the outage costs assumed for reliability simulation the higher economic benefits can be achieved as shown for maximum, average, and minimum cost model.

Source:
Christine Schwaegerl. “DG3&DG4 Report on the technical, social, economic, and environmental benefits provided by Microgrids on power system operation”. Siemens AG. 2009