Page 57 - Energize March 2022

TECHNICAL

of usable energy capacity. If a 30-minute Strategies to future-proof ESS the capability of a PC-based architecture
duration is required, then the system’s Strategy 1: Employ a flexible is shown below. Many of these
power capacity must be limited to 5 MW architecture deployments are technically feasible
so it can continue to yield the same 2,5 There are two primary controls on a PLC, but would have been much
MWh of energy capacity. Most PJM battery architectures for an ESS Energy more complex and costly, negating the
system operators responded to the Reg Management System (EMS): PLC-based commercial case for deployment.
D signal changes by simply cutting power and PC-based.
in half and reducing system availability. A programmable logic controller Strategy 2: Design for flexibility
However, since revenue is based on (PLC) is a hardened industrial computer, One solution for dealing with technology
capacity and availability, these operational designed originally for assembly lines. and market uncertainty is to design for
changes reduced investor revenue by PLCs are “hard” systems in that they ESS flexibility with an augmentation
greater than 50%. are programmed for a specific task, plan over the ESS project lifetime. In an
Wärtsilä ES&O, by contrast, made and they accept limited inputs and augmentation plan, additional battery
software and physical site changes to outputs to accomplish the task. In the capacity is added to the project site. The
maintain a high system availability and context of an energy storage EMS, augmented battery capacity can be used
keep the rated capacity of our systems PLCs are typically designed by inverter to supplement planned battery capacity
greater than 50%. We did this by re- manufacturers and coded for a specific losses due to battery degradation, or to
evaluating all the trade-off decisions inverter and battery technology. provide incremental capacity if future
that go into ESS operation. For example, Modifications are possible, but they market conditions support a larger
because the Reg D signal change increased take significant time and effort and system.
energy throughput, we reduced ESS typically require an engineer onsite for While augmentation plans make
temperature, which decreased degradation months at a time. This makes the cost sense in concept, few installed energy
but also decreased round-trip efficiency. of PLC modification relatively high. storage systems today have been
Because the signal change modified A personal computer (PC)-based planned for augmentation. As such,
the energy neutrality condition, we controller is built on multi-purpose there is no long-term track record of
modified our state-of-charge management industrial servers and is controlled by augmented battery storage systems.
algorithm, which impacted energy software. The PC-based architecture In addition, there are different schools
throughput and system performance. facilitates complex operation and of thought about how to safely and
These changes were enabled by optimization and allows for updates to effective augment ESS projects. Wärtsilä
future-proofing with an architecture of be delivered faster and at lower cost. is one of the few market participants
flexible controls, which we will discuss Wärtsilä’s GEMS controls platform is to have installed an ESS that has been
next. While future-proofing saved Wärtsilä designed with a technology-neutral planned for augmentation, and Wärtsilä’s
customers millions of dollars in PJM, other architecture, meaning that the same position is that there is a right way and
PJM systems faced tremendous losses. controls platform can be used with any a wrong way to design for flexibility with
Investors looking at the experience of battery and inverter technology with an augmentation plan.
the PJM merchant market for Reg D will minimal configuration. The right way to design for flexibility
use caution when entering into future The company tests all software is to plan the ESS layout for inverter-
merchant markets for ESS. modifications on a virtual machine that based augmentation. This design
Faced with a limited track record of replicates the technology characteristics requires leaving sufficient space for
the ESS installation base as well as market of each piece of hardware. Updates additional battery racks and designing
uncertainty, how can an ESS investor are performed only after the software wiring and cable trays for the future state
mitigate risk? The only option is to future- has been fully debugged in a lab of the system, where some racks have
proof current ESS investments to plan for environment and are then installed moved and additional racks are added.
changes in the future. remotely via a secure VPN and require With an inverter-based augmentation,
only five minutes of downtime. batteries will be wired in parallel only
Energy storage projects can be future- The PC-based flexible architecture with other batteries of the same vintage.
proofed by: enables various degrees of flexibility that The older batteries will have a similar
• Installing a flexible controls architecture each contribute to ESS future-proofing. state of health and therefore they will
• Planning the right way for battery In PJM, the flexible architecture allowed have similar resistance and current
capacity augmentation the company to react quickly to adverse output profiles.
• Tracking ongoing operation with a changes in the market. In other cases, The new batteries may have different
flexible warranty the flexible architecture has enabled it to characteristics, benefitting from higher
easily repurpose ESS assets when market performance, lower cost and a smaller
We see flexibility as the number one changes allowed for incremental value. footprint, thus requiring a smaller initial
factor. A table of case studies demonstrating capacity than batteries from the original

energize | March 2022 | 55