Renewable energy sources are intermittent in nature hence; it is therefore a challenging task to integrate renewable energy resources into the power grid.

1. Grid Management
Re-Balancing Power Generation
Power sector in India has witnessed tremendous
growth in its energy demand, generation
capacity, transmission and distribution networks.
Renewable energy generation in India has
been steadily on rise. With 175GW target of
clean energy, it became necessary to have
a grid that was highly adaptive (in terms of
supply and demand). A good electric supply
is one of the key infrastructure requirements
to support overall development; hence, the
opportunities for building smart grids in India are
immense. The fluctuating nature of renewable
energy, be it solar or wind, is a problem for
any grid in the world. As of March 31, 2017,
renewable energy sources accounted for
17.5 percent of all power generated in India.
The country’s total installed power generation
capacity was 326,848.54 MW with renewables
accounting for 57,260.23 MW. The solar sector
is witnessing installations at a rapid pace and
had the largest gain in share with 5.5GW of
installations in FY 2016-17. Solar accounts for
12,288.83 MW of the total installed capacity
which represents 3.76 percent of the overall
power generation. The installed capacity of
solar has almost doubled from 6,762.85 MW
in the previous financial year. Solar recorded
the largest increase with its share rising from
2.24 percent at the end of FY 2015-16 to 3.76
percent as of March 31, 2017, an increase of
1.52 percent.
According to the recently released India
Solar Market Update, it is predicted
that 2017 solar installations will reach
approximately 10 GW, a 130 percent
increase year-over-year compared
to 4.3 GW installed in 2016 as India
becomes one of the top solar markets in the
world after China and the United States. The
concern comes as India pushes for an ambitious
100GW solar power installation by 2022. As
more variable power generation sources are
added into the grid, the more difficult this
balancing becomes. This is where India’s
massive power grid system needs re-
balancing to deal with the fluctuating/
erratic nature of power generated
from renewable ene-rgy flowing
into the system and keep su-
pply in sync with demand. It
is time that power sector
stakeholders in India sho-
uld start discussing the
issues around grid
management and
initiate steps to
find potential
solutions.

3. NEXTracker’s 30MW CleanMax site in Tamil Nadu
GRID MANAGEMENT: ISSUES AND
CHALLENGES
Renewable energy sources are intermittent
in nature hence; it is therefore a challenging
task to integrate renewable energy reso-
urces into the power grid. Challenges
and issues associated with the grid inte-
gration of various renewable energy so-
urces particularly solar photovoltaic can
be broadly classified into technical and
non-technical:
Technical Issues:
Power Quality
• Harmonics
• Frequency and voltage fluctuation
Power Fluctuation
• Small time power fluctuations
• Long time or seasonal power fluctuations
• Storage
• Protection issues
• Optimal placement of RES
• Islanding
Non- Technical Issues:
• Due to scarcity of technical skilled workers.
• Less availability of transmission line to
accommodate RES.
• RES technologies are excluded from
the competition which discourages the
installation of new power plant for reserve
purpose.
Grid Integration Spans a Variety of Issues,
Including:
New Renewable Energy Generation
Power system planners can secure and
sustain investment in new variable RE
generation by aligning targets and incen-
tives with grid integration considerations.
Long-term, aspirational renewable energy
targets establish a vision that can drive
innovation in the policies and system ope-
rations that support clean energy. Also
critical are “grid-aware” incentives (e.g.,
rewarding wind and solar generators that
incorporate technologies that contribute
to grid stability), which both motivate inve-
stment in renewable energy and mitigate
negative impacts of integrating these res-
ources to the grid.
As planners consider scaling up variable RE
generation, the inherent variability of wind
and solar resources complicates evaluations
of whether a system with significant variable
RE has adequate supply to meet long-term
electricity demand. A variety of approaches
exist for estimating the capacity value of
variable RE, as well as techniques that
enable utilities and power system operators
to use wind and solar to reliably meet
electricity demand.
Integrating distributed photovoltaic (PV)
solar power results in unique benefits and
challenges compared to the integration
of utility-scale wind and solar power. Sig-
nificant localized growth in PV can raise
concerns such as voltage violations
and reverse power flow in low-voltage
distribution systems. However, various
studies have shown that positive impacts
(e.g., reduced line losses and avoided
generation costs) can also result from
distributed PV. Updating interconnection
standards, procedures, and distribution
planning methodologies to better reflect the
characteristics of distributed PV can help
realize these benefits and delay or even
prevent the need for grid reinforcement.
New Transmission
Scaling up variable RE generation requires
grid expansion and upgrades so that
power systems can access high-quality
solar and wind resources which are often
remote from existing transmission networks.
A well-crafted combination of policies,
rules, and procedures (designed, for exa-
mple, through an "RE Zones" approach)
encourages investment in large-scale
transmission expansion. These measures
not only improve the utilization of variable
RE, but also potentially defer the need for
network refurbishment.
Increased System Flexibility
Accessing sources of operational flexibility
becomes increasingly important in systems
with significant grid-connected solar and
wind energy. System operating procedures
and market practices, especially the imple-
mentation of forecasting, faster scheduling,
ancillary services, and grid codes and
power purchase agreements are often
among the least-cost options for unlocking
significant flexibility without significant
investments in new physical infrastructure.
Another important institutional flexibility
option is operational coordination between
balancing authority areas, which enables
sharing of resources through reserve
sharing, coordinated scheduling, and/or
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4. consolidated operation.
Other sources of flexibility include flexible
conventional generation and transmission
networks. Additionally, demand response
and storage are emerging as tools for
increasing flexibility at very high penetra-
tions of variable RE.
Options for procuring flexibility vary based
on the regulatory context. For vertically
integrated utilities, contractual or policy
mechanisms provide the primary basis
for encouraging the uptake of flexibility
measures. In contrast, partially- or wholly-
restructured power markets motivate flex-
ibility through incentives and market
design mechanisms, such as sub-hourly
dispatch, ancillary services markets and
price-responsive demand.
Planning for a High RE Future
In any power system, planning activities
include assessing long-range demand and
evaluating options for expanding capacity
and transmission. With the introduction of
significant variable RE generation, power
systems planning increasingly focuses on
evaluating options for increasing flexibility
across the power system.
Grid integration studies help establish the
flexibility requirements and build confidence
among investors and operators that the
power system can be operated reliably
at increased variable RE levels. A grid
integration study simulates the operation of
the power system under various scenarios,
identifies potential constraints to reliability,
and evaluates the cost of actions to alleviate
those constraints. Robust grid integration
studies are based on significant stakeholder
input, along with a broad set of foundational
data.
Although grid integration studies usually
include production cost simulations to
model unit commitment and economic
dispatch, determining the system-wide
costs of integrating solar and wind power is
much more challenging. The full costs and
value of variable RE assets to the power
system depend on dynamic and complex
interactions among these generators
and a system’s loads, reserves, thermal
generators, and transmission networks.
Grid integration studies illuminate the
obstacles and opportunities that wind and
solar integration could pose to a power
system helping to dispel grid integration
myths and misperceptions that inhibit
large-scale deployment. These studies
also lay the foundation for prioritizing and
sequencing grid integration investments.
THE CHALLENGES OF TODAY'S
EVOLVING ELECTRICITY GRID
Today’s power system must deal with a
number of stressors that power system
engineers of 100 years ago would have
never conceived of. Three major trends are
pushing for a change in how the electricity
grid is managed, giving utilities and system
operators plenty of new challenges to solve
to maintain reliability.
Renewable generation is intermittent and
difficult to control- The sun doesn’t always
shine and the wind doesn’t always blow
when customers need electricity. Instead
of a centralized location like traditional
generation, solar panels and wind turbines
are being installed at distributed locations
across the grid. Although they are a low-
cost source of clean and renewable energy,
GRID MANAGEMENT

5. these resources may inject power into the
grid at times and locations that can create
difficulty for grid operators. Problems
can arise, such as random changes in
voltage on distribution feeders, issues with
fault detection and unwanted generation
capacity which all affect the reliability and
sustainability of the grid.
Energy-consuming equipment is cha-
nging with the advent of new techno-
logies- Older electrical equipment such as
incandescent lights, heaters and motors
were designed to react to changes in vol-
tage and/or frequency. In fact, Conservation
Voltage Reduction (CVR) is based on this
concept. By reducing system voltage, the
electricity demand from these devices
will be reduced as well. Newer electronic
devices do not respond to changes in
system voltage or frequency, and they
now dominate many homes; they include
computers, lights (LEDs and CFLs), TVs,
entertainment systems, etc. In addition to
not responding to changes in grid voltage or
frequency, these devices consume power in
unusual patterns (called harmonics), which
can affect the delivery of power and cause
increased losses, equipment failure and a
few worst-case scenarios, building fires.
New protection systems and techno-
logies have enabled the modern power
grid to deliver more power than has ever
been possible- For example, new wire
technology has enabled existing wires to
handle higher electrical currents for short
periods of time; this can increase losses
by more than 4 times the norm. While
convenient and beneficial for today’s grid,
these types of technologies have played a
role in increased overall system losses from
5 to 7 percent to 9 to 12 percent.
ADDRESSING THE ISSUES OF MODERN
POWER SYSTEM
The way that utilities and electricity system
operators think about managing the grid
has already begun to change. Instead of
traditionally viewing grid management
as one-directional and black and white
(generation = controllable, demand =
random and uncontrollable), grid operators
are implementing demand management
programs, which engage electricity cus-
tomers to shift their electricity usage, imp-
rove their energy efficiency, enhance
the reliability of the power system and
sometimes offer cost savings or other
incentives for participation.
The next level of grid management involves
taking this important step even further.
With the use of new technology, utilities
are now able to view the demand side
as a single, controllable resource that
can respond to the real-time needs of
the electricity grid. The right intelligent
demand management technology can
help grid operators implement this type of
control without impact to their customers’
operations.
IMPROVING GRID INTEGRATION
To improve the grid integration, one has
to improve planning and accounting for
renewables (rather, for all generation),
factoring in their burden on the rest of the
grid such as transmission congestion. A
few specifics for this are:
Power Evacuation Planning- The starting
point requirement should be that if RE plants
are being built (and they are growing in
total wind/solar farm size to not just tens of
MW but hundreds), there must be sufficient
transmission capacity. This is often an
intra-state issue for now.
Enable Inter-State RE- This effectively
increases the balancing area, and isn’t
so transmission burdensome when the
favorable sites are near the border. The
problem isn’t the regulations disallow
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6. it, just that the present rules for inter-state
transmission require 15 minute firm sche-
dules, something impractical for renewable
power. The use of power exchanges for
improved (non-realtime) balancing is also an
option (subject to transmission constraints),
but this begs the question why are these
used so little today, even when prices are
ostensibly low, only a few Rs./kWh? The
reason isn’t technological but operational.
Current financial settlement norms, while
good for the exchanges’ risk profiles, make
it tough for states to buy much power since
they have enormous liquidity problems.
Improve Measurements, Predictions, and
Analysis for RE Generation, Including
Data Sharing- This could be through the
proposed Renewable Energy Management
Center(s) (REMC), which should also co-
ordinate with state and regional load dis-
patch centers. Data sharing is especially
important for wind power, which has much
more granular variance than solar power,
especially on a kilometer scale. REMCs
need not be a large or complex institution –
these could be envisaged as virtual centers
in synergy with Load Despatch Centers.
Demand Best (reasonable) Predictions
from Generators- CERC attempted to
mandate wind generators to predict, day
ahead, their output in 15 minute blocks
with a tolerance of 30% (with some cor-
rections allowed in 3 hour blocks), be-
yond which they would need to pay UI
(unscheduled interchange) charges as per
the current Availability Based Tariff (ABT)
as a Renewable Regulatory Charge within
the Renewable Regulatory Fund. There was
opposition, and the proposal is currently
on hold, pending validation (technically,
predictions are asked for, but penalties not
enforced). Improved predictions and nimble
grid operations are better than of simply
socializing the prediction variation costs.
Make Balancing a Proper Grid Req-
uirement- While there is now a separate
entity for Regional and National Load Des-
patch (POSOCO), India needs a comple-
tely independent Regional Transmission
Operator (also called an Independent
System Operator in some parts of the world).
Such an RTO/ISO must also coordinate
with state Load Despatch Centers, bala-
ncing their financial needs with grid ope-
rations. Importantly, all despatchers must
be discouraged from a mindset of load-
shedding as a balancing mechanism. One
simple option (as a thought exercise for
now), treat load shedding as having a cost,
say, equal to the next available resource in
terms of merit-order despatch. (In reality,
load shedding’s cost may be far higher to
society overall).
Strengthen the Grid- Even before we
think about ancillary services, there need
to be basic improvements to operations,
including the use of Primary frequency
control from generators with free-governor
mode of operations, whereby deviations in
frequency automatically signal the generator
to increase/decrease output. No generator
should be allowed to ignore or bypass
control signals like some reportedly do
today. In the future, frequency tightening
can be achieved by the use of Automatic
Generation Control (AGC) based on Area
Control Errors (ACE) as signaled by an
Area balancing authority.
Begin Ancillary Services in the Grid-
These value grid support mechanisms
beyond simple kilowatt-hour generation,
such as the ability to ramp-up/ramp-down
rapidly. Today, either the grid is left unstable
or such services are provided by the sub-
optimal provider (coal plants aren’t designed
for cycling production), without appropriate
compensation.
Move Towards Robust RE Technology-
Technologically, RE could provide more than
simple kWh generation, such as reactive
power, if it were incentivized to do so. In
addition, India must plan for the ability of
such generators to handle Low Voltage and
Fault Ride Through capabilities, something
China grappled with but ultimately enforced
in recent years. The difficulty of a weak
grid is exacerbated when RE generators
cannot handle low voltages or faults; they
trip, further weakening the rest of the grid.
Deploy Smart Grids to Make Demand
More Dynamic and Grids Robust- This
extends to storage solutions (which often
finds value not in energy (kWh) arbitrage
but also in providing ancillary services).
Both of these are discussed in more detail
in a separate chapter in this volume.
The century old grid is changing and the
question becomes is this a managed tran-
sition? Renewables aren’t just inevitable;
they should be supported and scaled up.
Much more subtle than the challenge of
meeting the peak is keeping the grid in
balance. Advanced transmission infra-
structure, updated grid integration and
operation mechanisms are key to scaling-up
solar to 100 GW by 2022. Combined with
improved pricing, storage technologies and
a Smart Grid, the policy push for generation
investments in green power can be not
just sustainable, but even help meet the
broader goals of the Indian power sector,
viz., access and affordability.
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- Laique@saurenergy.com
GRID MANAGEMENT