Solar Photovoltaic Generators With MPPT and Battery Storage in Microgrids

Solar Photovoltaic Generators With MPPT and Battery Storage in Microgrids

In a microgrid, the microsources and storage devices are connected
to the feeders through the microsource controllers (MCs)
and the coordination among the microsources is carried out by
the central controller (CC) [2]. The microgrid is connected to
the medium voltage level utility grid at the point of common
coupling (PCC) through the circuit breakers. When a microgrid
is connected to the grid, the operational control of voltage and
frequency is done entirely by the grid; however, amicrogrid still
supplies the critical loads at PCC, thus, acting as a PQ bus. In
islanded condition, a microgrid has to operate on its own, independent
of the grid, to control the voltage and frequency of the
microgrid and hence, acts like a PV (power-voltage) bus. The operation and management in both the modes is controlled and
coordinated with the help of microsource controllers (MCs) at
the local level and central controller (CCs) at the global level.
Similar to the traditional synchronous generator frequency
control [3], themicrogrid voltage and frequency control can also
be performed using droop control methods [4]–[8]. The present
work provides fast response characteristics for voltage and frequency
control as compared to the secondary control considered
in [8]. The analogy between inverter control and the synchronous
generator control in an islanded microgrid is studied
in detail in [9]. In the islanded mode, there is the necessity of
having a reference voltage and frequency signals in the microgrid
inverter control [10].
The operation and control of the inverter interface of renewable-
based distributed energy resources (DERs), like Solar
Photovoltaic (PV) in a microgrid, is a real challenge, especially
when it comes to maintaining both microgrid voltage and frequency
within an acceptable range. A voltage control method
based on traditional droop control for voltage sag mitigation
along with voltage ride through capability is proposed in [11].
A dynamic voltage regulation based on adaptive control is
proposed in [12], [13]. However, there are not many research
works performed on V-f or P-Q control using solar PV including
MPPT control and battery storage in microgrids. In
[14], frequency regulation with PV in microgrids is studied;
however, this work does not consider the voltage control
objective and lacks battery storage in the microgrid.
In [15], a small scale PV is considered in a grid-connected
mode to control the active and reactive power of the system.
Here, the control methods consider abc-dq0 transformation and
vice versa which is avoided in the present paper. In [16], power
modulation of solar PV generators with an electric double layer
capacitor as energy storage is considered for frequency control.
In [17], load frequency control is implemented in microgridwith
PV and storage; however, this work also lacks the consideration
of a voltage control objective. The voltage and frequency control
with solar PV and battery in microgrid with an induction
machine is investigated in [18]; however, this work does not explain
the transfer mechanism of controls to consider the battery
SOC constraint. In summary, the previous works in this topic
either lack the incorporation of an energy storage component
or the voltage control objective along with frequency control
or the incorporation of control transition in different scenarios.
The present work fulfills these gaps by considering all of these
objectives.