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Demonstration of Flow Batteries for the Prevention of Minimum Import
Violations
October 19, 2018
University of California, Riverside
Southern California Research Initiative for Solar Energy (SC-RISE)
www.scrise.ucr.edu
Center for Environmental Research and Technology (CERT)
www.cert.ucr.edu
Presented by:
Alfredo A. Martinez-Morales, Ph.D.
2018 UC Solar Research Symposium
U.S. Renewables Status
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In 2016, U.S. renewable electricity accounted for 18.3% of total installed
capacity and 15.6% of total electricity generation.
Source: 2016 Renewable Energy Data Book
California Solar PV Status
3
In 2016, California continued to lead with the most installed renewable electricity
capacity of any state (nearly 35 GW). California had the largest amounts of
cumulative installed solar capacity.
Source: Renewable Energy Data Book Department of Energy
Electro-chemical Storage
Status
4
According to IRENA 2016 report, during the last 20 years, global installations of
electrochemical storage deployment grew exponentially.
Source: ELECTRICITY STORAGE AND RENEWABLES: COSTS AND MARKETS TO 2030, IRENA
ZBFB is at a pre-commercial stage. Currently, installation costs are higher than
other types of battery. IRENA forecasts that by 2030, ZBFB costs are expected to
decrease to one third of current costs.
Source: ELECTRICITY STORAGE AND RENEWABLES: COSTS AND MARKETS TO 2030, IRENA
Zinc Bromine Flow Battery
(ZBFB)
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Source: Self-Sufficient, High Resilience Microgrids, Primus Power
Conventional ZBFB EnergyPod ZBFB
EnergyPod ZBFB
Victor Valley Wastewater Reclamation Authority (VVWRA) Facility 7
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Project Summary:
• Deployment, demonstration, and validation of a ZBFB at the VVWRA
Facility;
• Objective is to demonstrate the potential for minimizing (preventing) the
minimum import violations at the VVWRA facility by optimizing the utilization
of the ZBFB;
• System is composed of two on-site 800 kW biogas generators, 200 kW/
1 MWh ZBFB, SCADA system, and controller;
• System optimization is achieved by a heuristic control framework;
• Minimize the operational power buffer;
• Increase on-site renewable energy; and,
• Reduce the amount of water (in treatment) being discarded.
VVWRA Project
9
March 2016 Week 4
Minimum Import
Violation
Minimal Import
Violation
Generators
decoupled
VVWRA receives
energy from two
sources:
• on-site biogas
generators
• Southern California
Edison (SCE) grid.
• Minimum Import
Violation
• Power Import
< 80 kW
• Lasts for > 2 s
VVWRA System Layout
10
VVWRA Control
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• Energy management goals are changed from reducing peak demand by
discharging battery to maintaining net load above 80 kW by charging
battery.
• The BESS acts as the net load regulator to trigger the onsite generators to
produce more/less power.
• The frequency (less than 2 second) to operate the battery is much faster
than the previous battery control methods.
The BESS will smooth the facility load and maintain a load margin above the
minimum import threshold.
VVWRA Control Requirements
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States Conditions SCE Generator
Actions
0: Steady State SOClower < 𝑆𝑂𝐶< 𝑆𝑂𝐶𝑢𝑝𝑝𝑒𝑟
Steady No Output
Change
1: Charge Initiate SOC ≤ SOClower Increase Increase
Output
2: Charge Maintain SOC ≤ SOC𝑚𝑖𝑑 Steady No Output
Change
3: Discharge Initiate SOC ≥ SOCupper Decrease Decrease
Output
4. Discharge Maintain SOC ≥ SOCmid Steady No Output
Change
VVWRA Control States
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State 1:
Charge
Initiate
State 2:
Charge
Maintain
State 0:
Steady
StateSOC ≥ SOCupper
SOC ≤ SOClower
SOC ≥ SOC𝑚𝑖𝑑
State 3:
Discharge
Initiate
State 4:
Discharge
Maintain
SOC ≤ SOC𝑚𝑖𝑑
State 0:
Steady
State
VVWRA Simulation Results
VVWRA LabVIEW Simulator
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VVWRA LabVIEW Simulator
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Simulation Results
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Simulation Results
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Reducing the Occurrence of Minimum Import
Violations
Under certain conditions the simulation is unable to prevent the
minimum import violation. There are two main reasons :
1) The facility load drops sharply
2) The battery is engaged in a “refresh cycle”
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Minimum Import Violation:
Load Drops Sharply
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Minimum Import Violation:
ZBFB is in ‘Refresh Cycle’
Decreasing Occurrence of Minimum Import
Violation
To improve the prevention of minimum import
violations, optimization is needed to:
1. Determine what is the most appropriate
steady range
2. Determine what is the most optimal
threshold value
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Decreasing Occurrence of
Minimum Import Violation
Steady Range (130 kW ~ 150 kW), trigger 100 kW, set 110 kW
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Decreasing Occurrence of Minimum
Import Violation
Steady Range (100 kW ~ 120 kW), trigger 90 kW, set 95 kW
Steady Range (130 kW ~ 150 kW), trigger 100 kW, set 110 kW
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Conclusions
• New technologies have a lot of potential, but demonstration and validation is
needed for de-risking investment and adoption;
• Operational constraints are critical for properly managing and utilizing new
technologies;
• Performing use case studies and application-based projects will validate the
limitations and constraints of new technologies for validating the applicability
of new technologies; and,
Thank you
