Article on Integrated Wind Energy Storage that featured in Renewable Watch magazine (August 2014). The article covers Energy Storage's applications specific to Wind Power for the Indian market.

1. P E R S P E C T I V E
Integrated Wind Energy Storage
Wind power continues to
command the lion’s share
of all renewable power
installations in India. However, the
industry and the grid are constantly
challenged by its inherent variability,
which makes it more challenging to
despatch higher amounts of wind
power into the grid. As a result,
operators can be asked to back down,
causing potential revenue loss to the wind
farm developer.
Energy storage has been known to help
address some of these challenges; how-ever,
many questions persist about its
relevance in the Indian context, including
storage applications specific to the coun-try,
the maturity or credibility of energy stor-age
technology and economic feasibility.
Energy storage is like a piece of hardware
as well as a technology platform that en-ables
multiple software applications.
Does this sound similar to the smart-phone
and applications revolution that
started a few years ago? The collective
value of a smartphone’s many applica-tions
far outweighs the costs and benefits
of the hardware or individual applications,
as is the case with energy storage.
While energy storage has applications
across the power generation, transmis-sion,
distribution and consumption value
chain and may include multiple sources
(such as solar) and other industries (such
as telecom), this article focuses on energy
storage integrated with wind power.
India-specific applications
Energy storage has multiple applications
that can enable higher penetration of wind
48 ● Renewable Watch ● August 2014
power in India’s energy mix, while improv-ing
individual wind farm economics.
These are as follows...
Predictable power
The Central Electricity Regulatory Com-mission
(CERC) introduced the Renewable
Regulatory Fund (RRF) mechanism with
the objective of increasing the penetration
of wind power through effective scheduling
and forecasting. However, given the intra-day
and seasonal variations in wind speed
as well as operational issues associated
with forecasting, many wind farm develop-ers
found it difficult to comply with the
RRF’s accuracy expectations. A small
amount of energy storage could be
immensely useful in this case to offset any
minor deviations in the actual generation
from the forecast. An intelligent charge and
discharge operation of the battery can help
developers comply with the RRF, avoid
penalties for deviations from the forecast
and transform this infirm source of power
into a firm one. It also helps the grid oper-ator
to avoid charges associated with
interregional power transfer to coun-teract
wind power variation.
Curtailment loss redemption
Most wind farms in India are locat-ed
in remote areas with a relatively
weak grid. Frequent grid outages
combined with curtailment during
the peak wind season often cause gen-eration
losses and therefore revenue
losses for developers. Energy storage
can help recoup such spilled power loss-es
by storing energy generated during
this period and later discharging the
stored energy when the curtailment limi-tation
is relieved. It also avoids shutting
down turbines or idling them, thereby
preserving balance life. Depending on
the available transmission capacity and
grid situation, curtailment might still play
an important role for the grid, often as a
means of deferring transmission expan-sion;
however, the application of energy
storage insulates the wind farm develop-er
from associated losses.
Ramp control
Wind farms are known to experience sud-den
gusts that result in a surge in gener-ation
in a very short period of time. These
steep power ramps are difficult to absorb
by the grid and could lead to the wind
farms being asked to back down. Modern
wind farm control systems come with a
ramp control application that controls the
rate of increase of power in a short inter-val,
and the excess power generated dur-ing
this time can be stored in a battery for
later discharge. Ramp control also plays
an important role in scenarios of released
curtailment, where a wind farm will still
have to constrain its up-ramp depending
One platform, many applications
By Milesh Gogad, Senior Product Manager, GE Renewables
Energy storage is like a
piece of hardware and a
technology platform that
enables multiple soft-ware
applications.

2. P E R S P E C T I V E
on a ramp rate restriction. To an extent,
down-ramp, or rate of change of wind
power drop can also be controlled by util-ising
energy storage.
Potential participation in ancillary services’
market
The CERC staff paper, “Introduction of
Ancillary Services in Indian Electricity
Market”, recommends introducing three
new products on power exchanges to im-prove
and enhance the reliability and secu-rity
of the electrical power system. These
are ancillary services for frequency sup-port,
voltage control and black start – pro-viding
additional revenue streams for wind
power producers. Energy storage would
be a critical tool for participating in these
upcoming markets. Energy storage pro-vides
the necessary control required for
precise power regulation in order to meet
ancillary service requirements. Given the
benefits that such services bring to grid
operation and reliability, the incentives that
are offered should drive the economic
case for utilising energy storage.
Technology maturity and credibility
While energy storage is a proven technol-ogy,
its application when integrated with
wind power continues to evolve around
the world. GE demonstrated an integrated
wind energy storage technology at a wind
farm in the US. The company configured
three battery-enabled software applica-tions
that integrate with the wind turbine:
50 ● Renewable Watch ● August 2014
Predictable power application
z Predictable power, which smooths out
the short-term peaks and valleys in wind
power and makes it predictable over
periods of 15 to 60 minutes.
z Ramp control, which allows the turbine
to capture “wasted” wind power and
store it in the battery so that operators
can capture revenue previously left on
the table.
z Frequency regulation, which allows
wind farms to store energy in the bat-tery
and respond immediately to load
changes with precision as power
demand changes throughout the day
and grid operators must keep up with
its constant fluctuation.
Economic feasibility
The financial viability of energy storage
depends on a number of factors. These
include specific applications, prevalent
market mechanisms and monetisation
avenues, integration architecture, battery
chemistry and associated costs, and
optimal sizing.
Integrating the battery into the wind turbine
allows wind farm developers to benefit
from energy storage without the high costs
of installing farm-level battery storage. This
configuration further integrates battery
technology with its software applications.
The hardware connects to the turbine’s
existing converter, minimising the changes
required to accommodate the battery sys-tem.
Initial estimates indicate up to 20 per
cent savings from shared balance of plant
costs with turbine-level integration archi-tecture
over a farm-level one. In addition,
distributed energy storage offers the
advantage of higher reliability, since farm-level
reliability has a single point of failure
and therefore hedges the risk.
Conclusion
Energy storage can help address many
challenges inherent in wind power genera-tion,
including those that are specific to
India. It is important to consider the value
of multiple algorithms from essentially the
same hardware while evaluating the bene-fits
of energy storage against the invest-ment.
Just as the smartphone and appli-cations’
ecosystem improved access to in-formation
and enhanced user experience,
energy storage can also enable higher
penetration of wind power in the energy
mix, while making it easier to integrate this
abundant resource into the grid. ■
Ramp control application Frequency control application