IEEE Electrification Magazine - September 2015 - 55

1.5
Dynamic Control Signal
Resource Response

0.5
0
-0.5
-1

Normalized Output (MW)

Traditional Control Signal
Resource Response

1
0.5
0
-0.5
-1

:2
0

:0
0

0:
58

:4
0

0:
50

:2
0

0:
41

:0
0

0:
33

:4
0

0:
25

:2
0

0:
16

:2
0

:0
0

0:
58

:4
0

0:
50

:2
0

0:
41

:0
0

0:
33

:4
0

0:
25

:2
0

0:
16

0:
08

-1.5

0:
08

Normalized Output (MW)

Time (min)
(b)

Time (min)
(a)

Figure 3. The two PJM regulation control signals-traditional (RegA) and dynamic (RegD)-and the corresponding resource responses. (a) A natural gas combined cycle plant that follows the traditional signal. (b) A lithium-ion (Li-ion) battery resource that follows the dynamic signal.

pay-for-performance, PJM has seen
98 MW of grid-connected advanced
energy storage devices operating in
the regulation market, an example of
which is shown in Figure 4. In addition, 60 MW are under construction,
and 365 MW are under interconnection study. In addition, rules allowing
demand-side resources to participate
in PJM markets have enabled 6.5 MW
of PEV battery and thermal energy
storage systems to provide regulation from behind the customer's
retail meter.
Resulting market designs from the
implementation of FERC Order 755 vary
across the United States; however, the concept is consistent. It
rewards higher-quality regulation service and compensates
fast-response resources for the additional value they contribute toward system control results, which brings more efficient
balancing and more opportunities for advanced energy-storage technologies. This is important to recognize because the
more renewable energy connected to the power system, the
more challenging it is for the operators to balance. As such, it is
expected that under high-renewable penetration scenarios the
need for balancing reserves, particularly regulation, will
increase. A recent renewable integration study of the PJM grid
concluded that, if 30% of the energy in PJM came from renewables, the PJM system may need to procure up to an additional 127% of regulation reserves, depending on the mix of
renewables [2]. Additionally, the amount of regulation procured in each hour may need to become a dynamic target
based on the percentage of forecasted renewables relative to
load. However, power grid operators choose to adjust their
procurement of regulation in response to increasing renewables. Pay-for-performance regulation can manage increasingly

The regulation
dispatch signal is
used to fine-tune the
system by ramping
generation up or
down when supply
and demand are
out of balance.

complex balancing operations, reduce
cost effects for consumers, and open
opportunities for emerging technologies like energy storage.

Big Storage, Small Devices

PJM has some of the largest battery
energy storage devices in the world
operating in its footprint. However, in
the future, it may be the smallest
devices that account for the largest
amount of storage capacity. This "silver
buckshot" (vs. silver bullet) approach to
energy storage is emerging in PJM and
elsewhere, particularly through the use
of thermal storage devices such as
heaters, plug-in electric vehicles and loads such as variable
speed motors.
These technologies are compelling because they are
deployed for other purposes besides grid storage (e.g., hot
water or driving), meaning their incremental cost to control

Figure 4. One of the largest advanced storage resource operating in
PJM is the AES Energy Storage's Tait facility, a 20-MW Li-ion battery
located in Ohio. (Photo courtesy of AES.)

IEEE Electrific ation Magazine / S EP T EM BE R 2 0 1 5

Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2015