In a competitive electricity market, sufficient freedom is provided to the market
participants to interact among themselves. Here, both the buyers and sellers try to buy and sell
electric power so as to maximize their profit. In such a situation, to meet the desired
transactions, power flow in the transmission network violates some of the physical limits of
the transmission system. This condition is called the congestion of the transmission
network. The undesirable effects of the congestion include volatility and increase of the
electricity cost, jeopardizing the system security and reliability. Hence, to maintain the
market efficiency, it is very important that the congestion be relieved in a fast, systematic
and efficient manner.
The phenomenon of congestion is observed in both regulated and
deregulated power systems. In regulated power market, since generation, transmission
and distribution are managed by a single entity, congestion management is relatively
simple. But, in a competitive power market, the situation is more complex.
Congestion can be relieved by using available resources like rescheduling
of generators and on-load tap changers. System operators usually prefer these
methods to relieve congestion. Further, congestion can also be relieved by providing
information of a particular line getting congested and financial incentives to the consumers so
as to adjust the load within the system constraints. In extreme situations, the
transactions may be physically curtailed to relieve congestion. But the system operators keep
this as the last option due to the inconvenience caused
to the system users. |
