  This paper proposes a decentralised secondary voltage control strategy that
has several benefits over the existing centralised strategies. For that, a new
structure for the control is proposed in terms of an inner and outer loops for
each generator. The individual generators of a particular zone participate in
the secondary voltage control by aligning their reactive powers with respect to
the pilot point voltage reference. The decentralised nature of the proposed
control strategy enables plug and play operation: run with different numbers of
generators without any need of regulators reconfiguration, resilience in case
of generator failure. This allows one to use such control to integrate
renewable generators to existing secondary regulations alongside with the
classic generators. The proposed control strategy is implemented using a
model-free control scheme that does not require a higher order complex model of
the power grid. The deployment of a discrete-time intelligent proportional
controller simplifies the tuning of the controller gains. The proposed strategy
is validated on a four generator power system model in MATLAB/
Simulink/Simelectrical environment. Simulation results are presented to show
the effectiveness of the proposed strategy along with different case studies
such as load perturbation, transmission line perturbation, generator
disconnection and delay in pilot point voltage measurement to highlight its
robustness.
