  With the fast growth of wind power penetration, power systems need additional
flexibility to cope with wind power ramping. Several electricity markets have
established requirements for flexible ramping capacity (FRC) reserves. This
paper addresses two crucial issues that have rarely been discussed in the
literature: 1) how to characterize wind power ramping under different forecast
values and 2) how to achieve a reasonable trade-off between operational risks
and FRC costs. Regarding the first issue, this paper proposes a concept of
conditional distributions of wind power ramping, which is empirically verified
by using simulation and real-world data. For the second issue, this paper
develops an adjustable chance-constrained approach to optimally allocate FRC
reserves. Equivalent tractable forms of the original problem are devised to
improve computational efficiency. Tests carried out on a modified IEEE 118-bus
system demonstrate the effectiveness and efficiency of the proposed method.
