  To stabilize the frequency of the renewable energy sources (RESs) dominated
power system, frequency supports are required by RESs through virtual inertia
emulation or droop control in the newly published grid codes. Since the
long-term RES prediction involves significant errors, we need online configure
the frequency control parameters of RESs in a rolling manner to improve the
operation economics under the premise of stabilizing system frequency. To
address this concern, this paper proposes a frequency constrained stochastic
look-ahead power dispatch (FCS-LAPD) model to formulate the frequency control
parameters of RESs and Energy Storage Systems (ESSs) as scheduling variables,
which can optimally allocate the virtual inertia and droop coefficient of RESs
and ESSs. In this FCS-LAPD model, the uncertainties of RESs are characterized
using Gaussian Mixture Model (GMM). The required reserves are determined by
frequency control parameters, and the reserve cost coefficients are adjusted
properly to allocate the reserves according to the predicted power generation.
Due to the nonlinearity of the frequency nadir constraint, a convex hull
approximation method is proposed to linearize it with guaranteed feasibility.
The proposed FCS-LAPD is ultimately cast as an instance of quadratic
programming and can be efficiently solved. Case studies on modified IEEE 24-bus
system and a provincial power system in China are conducted to show the
effectiveness of the proposed model.
