In recent years, photovoltaic has generation become the most popular renewable energy based
generations. However, this power generation cannot supply constant electric power output and
sometimes cause the imbalance between supply and demand. To alleviate the mentioned problem, a
number of Heat Pump Water Heaters (HPWH) and Electric Vehicles (EV) are used as new control
equipment for Load Frequency Control (LFC) in order to suppress the frequency fluctuation caused by
such a large amount of renewable energy sources. However, Due to the system uncertainties such as
system parameters variation, the conventional controllers which are designed without taking system
uncertainties into account in the controller design may lose the control effect and fail to damp the
frequency deviation. This will affect the quality of supply and may deteriorate the system stability.
This paper proposes, A New load frequency control (LFC) using the coefficient diagram method
(CDM) technique in the presence of variable solar power & thermal power have been presented. The
CDM technique has been designed such that the effect of the uncertainty due to governor and turbine
parameters variation and variable solar power & load disturbance is reduced. Digital simulations for a
power system are provided to validate the effectiveness of the proposed scheme. A performance
comparison between the proposed and a conventional integral control scheme is carried out confirming
the superiority of the proposed CDM technique in smart power system