Page 16 - PEN eBook May 2023

SMART ENERGY SMART ENERGY

Power Electronics and

Energy Storage in Grid Figure 2: U.S. large-scale battery storage additions (Source: U.S. Energy Information Administration, “Battery Storage in the
United States: An Update on Market Trends,” December 2020)

Modernization 120-MWh BESS in Escondido, California, and the Tesla POWER ELECTRONICS SYSTEMS
129-MWh system in Australia. Figure 2 shows the U.S.
Power electronics systems (PES) provide two critical
functions within the grid:
large-scale battery capacity addition, for the time
periods from 2003 to 2020 and 2021 to 2023. This
By Sonu Daryanani, contributing writer for Power Electronics News shows the acceleration in both standalone and ▶ Convert energy efficiently between different
co-located storage systems. types, e.g., DC to AC

As the world shifts to increased use of renewable While the price of batteries is coming down ▶ Control the flow of electrical energy
energy, a transformation is occurring in the storage significantly, as shown in Figure 3, the overall BESS
and conversion of this energy for everyday household cost includes several other components, such as As shown in Figure 4, a PES is needed from energy
use. In this article, we will highlight a presentation the power conversion system, which includes a generation, transmission to its distribution.
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delivered by Jacob Mueller, a senior member of the bidirectional inverter, an energy management system
technical staff with the energy storage technology that provides safety and data-logging controls and In the U.S., the Office of Electricity’s Transformer
and systems department at Sandia National other components like the container, electrical Resilience and Advanced Components (TRAC) program
Laboratories, on the key trends and challenges distributions and HVAC/thermal management. highlights the future roadmap in various aspects of
involved in this transformation, focusing on the role energy generation and distribution. One aspect of
of power electronics and energy storage. this covers the solid-state power substation (SSPS).
An SSPS power converter within the substation can
GRID ENERGY STORAGE be constructed as a modular collection of power

A bidirectional electrical energy storage system is electronics building blocks. Scalability is a key end
capable of absorbing the energy and storing it for goal. The SSPS roadmap, shown in Figure 5, highlights
a period of time before sending it in the form of the trend to increased power density going from SSPS
electricity. It can come in many forms, as shown in Figure 1: Energy storage techniques versus power and 1.0 to SSPS 3.0.
Figure 1. Variable renewable energies like wind and discharge time (Source: U.S. Department of Energy,
solar are driving the growth of battery storage systems. “Potential Benefits of High-Power, High-Capacity Batteries,” Increasing the working voltage is one of the best
January 2020)
A distributed approach (termed DER, for distributed routes to increasing power density. A battery-cell
energy resource) using smaller batteries at the source voltage is fixed by the cell chemistry. Hence, several
of generation can make the grid flexible and reliable. As Figure 1 shows, there is no ready solution for cells are stacked in a series combination to create
Current battery technology is mostly applicable to seasonal long-duration energy storage. modules, which can then be series-connected to
short-duration energy storage, in the range of seconds create a rack. Racks can then be parallel-connected
to hours. Pumped hydro, compressed air and thermal Lithium-ion battery energy storage systems (BESS) for capacity to create an individual system. A power
methods offer hours to daylong storage but can often are dominant within battery storage technologies. Figure 3: Price trend of BESS (Source: Bloomberg New Energy control system (PCS) controls this system and presents
be limited by natural resources and terrain. Examples of large-scale installations include the AES Finance) a voltage to the DC-link.

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