  The potential of demand side as a frequency reserve proposes interesting
opportunity in handling imbalances due to intermittent renewable energy
sources. This paper proposes a novel approach for computing the parameters of a
stochastic battery model representing the aggregation of Thermostatically
Controlled Loads (TCLs). A hysteresis based non-disruptive control is used
using priority stack algorithm to track the reference regulation signal. The
parameters of admissible ramp-rate and the charge limits of the battery are
dynamically calculated using the information from TCLs that is the status
(on/off), availability and relative temperature distance till the switching
boundary. The approach builds on and improves on the existing research work by
providing a straight-forward mechanism for calculation of stochastic parameters
of equivalent battery model. The effectiveness of proposed approach is
demonstrated by a test case having a large number of residential TCLs tracking
a scaled down real frequency regulation signal.
