2 research outputs found
Control Analysis for Grid Tied Battery Energy Storage System for SOC and SOH Management
Frequency regulation is an important part of grid ancillary services in the UK power system to mitigate the impacts of variable energy resources and uncertainty of load on system frequency. The National Grid Electricity Transmission (NGET), the primary electricity transmission network operator in the UK, is introduced various frequency response services such as firm frequency response (FFR) and the new fast enhanced frequency response (EFR), which are designed to provide real-time response to deviations in the grid frequency. Flexible and fast response capabilities of battery energy storage systems (BESSs) make them an ideal choice to provide grid frequency regulation. This thesis presents control algorithms for a BESS to deliver a charge/discharge power output in response to deviations in the grid frequency with respect to the requisite service specifications, while managing the state-of-charge (SOC) of the BESS to optimize the availability of the system. Furthermore, this thesis investigates using the BESS in order to maximize triad avoidance benefit revenues while layering UK grid frequency response services. Using historical UK electricity prices, a balancing service scheduling approach is introduced to maximize energy arbitrage revenue by layering different types of grid balancing services, including EFR and FFR, throughout the day. Simulation results demonstrate that the proposed algorithm delivers both dynamic and non-dynamic FFR and also EFR to NGET required service specifications while generating arbitrage revenue as well as service availability payments in the balancing market. In this thesis, a new fast cycle counting method (CCM) considering the effect of current rate (C-rate), SOC and depth-of-discharge (DOD) on battery lifetime for grid-tied BESS is presented. The methodology provides an approximation for the number of battery charge-discharge cycles based on historical microcyling SOC data typical of BESS frequency regulation operation. The EFR and FFR algorithms are used for analysis. The obtained historical SOC data from the analysis are then considered as an input for evaluating the proposed CCM. Utilizing the Miner Rule’s degradation analysis method, lifetime analysis based on battery cycling is also provided for a lithium-titanate (LTO) and lithium-nickel-manganese-cobalt-oxide (NMC) battery. The work in this thesis is supported by experimental results from the 2MW/1MWh Willenhall Energy Storage System (WESS) to validate the models and assess the accuracy of the simulation results
Scheduling of grid tied battery energy storage system participating in frequency response services and energy arbitrage
Battery energy storage
systems
(BESS)
are
widely used to smooth
power
fluctuations
and maintain the voltage and
frequency of the power feeder at a desired level.
T
he National Grid Electricity Transmission (NGET), the primary electricity
transmission network operator in the UK, has introduced various frequency response servic
es that are
designed
to provide a
real
-
time response to deviations in the grid frequency.
In this study
,
a
control
algorithm is
developed
which generates a
charge/discharge power output with respect to deviations in
the grid frequency and the requisite
service
specifications. Using
historical
UK electricity prices, a new
balancing
service scheduling approach
has
also been
developed to
maximize
energy
arbitrage
revenue
by layering
different types of balancing services
throughout the day
. Simulation result
s show that the
proposed algorithm delivers both dynamic and non
-
dynamic firm frequency response (FFR) and also enhanced frequency
response (EFR) to
NGET
specifications while
generating arbitrage revenue
as well as service availability payment
s
in the
balancing market. A comparative study is also presented to compare the yearly arbitrage revenue
obtained
from
the work
presented in this
paper and
a
previous
reference study
.
Finall
y, exper
imental results of
a
grid
-
tied
2MW
/1MWh
BESS
have
been used
for verification purposes