Wind power and electricity markets - Wind Power Integration: Connection and System Operational Aspects - page 253

as costs should be allocated to those who can control them, thus encouraging them
to invest in solutions to reduce them. Certain supply system costs are best managed
by the wind generators themselves - e.g. the need for reserves to balance wind can
be reduced by better wind forecasting. Other costs are best dealt with by the net-
work operator (e.g. losses) and others by a combination of generators and network
operators (e.g. reactive power).
Proper allocation of the costs of wind power will optimise the amount of wind
generation. Many in the wind power industry are motivated to obtain as much wind
generation connected as soon as possible. However, if this is allowed to occur
without proper allocation of the costs to the wind industry, wind generating capa-
city may saturate at a lower level of penetration than would otherwise be feasible.
Therefore, it is in the long-term interest of the wind power industry to accept and
pay the costs that it imposes on the system. Quantification of these costs is non-
trivial and is often the subject of debate.
Many reports have been published on the impact of wind on electricity systems
(ESBNG, 2004a; Gardner et al ., 2003). The studies attempt to quantify the impacts
of wind generation on the system in terms of additional reserves (Doherty and
O'Malley, 2005), impact on emissions (Denny and O'Malley, 2006) and system
inertia (Lalor et al. , 2005), starts and stops of other units, ramping, load following,
etc. The technical impacts are then converted into costs. These studies can be
controversial for a number of reasons. First, other generation technologies impose
costs on the system, yet they do not attract as much attention. For example, possible
forced outage of nuclear power stations in Britain sets a requirement for 1,320 MW
of emergency reserve, much greater than the wind sector's need for regulating
reserve. Second, the studies are very difficult to perform because they are looking
into the future, and there is limited experience of operating power systems with
substantial amounts of wind power. There is a consensus, however, that wind
power does have some adverse impact on power system operation, in particular the
associated need for balancing and ancillary services, and that this adds to the cost of
wind power. The incremental cost increases with wind penetration, and it is this
aspect that leads commentators to suggest that there is a maximum level of wind
generation that should be allowed. However, it is also clear that these costs are
different for different systems due to the nature of the network, other generating
plant and system operating practices.
There is no doubt that there are plant portfolios that are particularly suited to
wind power and there are those that are not. For example, flexible open-cycle gas
turbines may be deemed to be beneficial to wind power, while in contrast inflexible
base-loaded nuclear generation is not complementary. In all electricity systems
there are plant and load portfolios that are more beneficial to wind power than
others. The best mixes are different for different regions, climatic conditions, nat-
ural resources, industrial characteristics, etc. Large-scale wind generation with its
particular characteristic is altering the load/generation mix and if it is to thrive the
market needs to encourage investment in plant that will optimise the mix.
The reliability and security of a power system requires an instantaneous
power balance. Therefore, the variability of wind power over different time