Nuevas estrategias para la contribución de los parques ... - RiuNet

Nuevas estrategias para la contribución de los parques eólicos al control de frecuencia de los sistemas eléctricos
generation, a bad performance is detected. In these cases fast frequency variations
associated to the low inertia of the system lead to an excessive load‐shedding. As a
consequence the frequency undergoes severe oscillation levels activating the discon‐
nection of intermittent generation units. In extreme cases this can lead to the col‐
lapse of the power system. In these cases it has been proven that the contribution of
wind farms to the frequency control achieves a proper automatic load‐shedding and,
consequently, a fast stabilization of the frequency with a very small quasi‐static devi‐
ation.
For the remaining scenarios, including valley situations in which inertia levels are
higher, as conventional generation are at the minimum operating level, special atten‐
tion has been paid to how the contribution of wind farms to the frequency control
affects the automatic load‐shedding schemes.
It has been proven that when small incidents take place, as can be compensated
with conventional generation effects, wind farms may reduce the amount of load
shed. On the other hand, under the appearance of relevant incidents as load‐
shedding is unavoidable the presence of wind farms in the power system may be
detrimental. While the wind generators maintain its power increment, the power
system behaves as if this increment came from conventional generation or as if the
incident causing the frequency variation had a smaller magnitude. In some scenarios
this leads to a smaller amount of load shed at first. If this is not sufficient for the fre‐
quency stabilization the load‐shedding process will continue until lower frequency
loads are shed. As a result the frequency deviation increases and the load‐shedding
process does not correspond to the incident magnitude.
In many cases the power increment induced by the frequency control of the wind
generators leads to a reduction of its rotating velocity lowering the generated power.
Additional control algorithms have been proposed with the aim of recovering the
initial velocity stable regime.
Finally, the effect of wind energy generation in electricity balancing markets has
been evaluated in the particular case of Spain and compared with other regions.
From these comparative analyses several improvement measurements have been
proposed with the aim of progressively improving the integration of wind energy in
electricity markets.
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