IEEE Electrification - September 2021 - 12

TECHNOLOGY LEADERS
numerical metrics, which include a
variety of characteristics, such as reliability,
resilience, performance,
dynamics, controllability, observability,
efficiency, robustness, survivability,
life span, economics, environmental
impact, and interoperability (see the
" A Metric Space for Microgrid Design
Guidance " section).
The second input, (i2) predesign of
components, proposes an initial
design of the relevant components of
the microgrid, including the generators,
loads, storage systems, networks,
switches, transformers, and so on. The
third input, (i3) physics-based models,
outlines the mathematical models
that describe the dynamics of the
components and the interconnections
defined in the second input, including
subtransient, transient, and steadystate
dynamics, and the high-, mid-, or
low-fidelity models of the electromagnetic
and mechanical aspects, the economic
characteristics and so forth.
The fourth input, (i4) real data, provides
information from experiments
to assist with the analysis of the
microgrid, validates the models, and
reduces the inherent model uncertainty.
The fifth input of the CCD process,
(i5) case studies, proposes key
cases to test the microgrid, including
grid-connected and islanded cases,
different levels of renewable generation
and electricity costs, a variety of
faults in key points of the network
and the communication system, variations
of the network topology,
extreme weather cases, a transition
among system states, and cases
defined by the standards.
With this information (i1 to i5),
the CCD methodology develops the
optimization of the microgrid. The
first CCD method, known as controlinspired
paradigms (A1), proposes
new design solutions based on a
practical engineering understanding
of dynamics and control. Based on
control engineering principles, this
approach uses physics-based low-/
mid-fidelity models in frequency and
time domains and tools like Bode
and Nichols diagrams and Root locus.
With the appropriate power electronics,
sensors, and control algorithms
and looking at the dynamics of the
microgrid, it proposes solutions that
optimize aspects like controllability;
observability; stability; damping;
time delays; multi-input, multi-output
coupling; integrity; fragility; actuator-sensor
colocation; control
authority; nonlinearities; and others.
The second CCD method, known as
co-optimization (A2), uses a formal mathematical
methodology with the nonlinear
low-/mid-fidelity dynamic models
of the microgrid and multivariable-constrained
optimization theories and iterative
processes. The third CCD method,
co-simulation (A3), uses multiscale, multiphysics,
high-/mixed-fidelity dynamic
models of the microgrid in an iterative
simulation process, frequently with
methodologies that include Monte
Carlo algorithms, data-based models, or
machine learning techniques.
Each method provides some benefits
but also has some limitations. In
Mathematics
Control CCD of Microgrids
i4
Real Data
* Lab/Full-Scale
Experiments
* Analysis
* Model
Validation
A
i5
Case Studies
* Operational
Cases
* Extreme Cases
* System States
Engineering
* Design of Subsystems
* Sensors, Actuators, Networks
* Dynamics and Control Design
* Physics-Based Models, Frequency/Time Domains
* Reduced-Order, Low-/Mid-Fidelity Models
Figure 6. The CCD methods. O&M: operation and maintenance.
12
IEEE Electrification Magazine / SEPTEMBER 2021
Control -
Inspired
Paradigms
A1
1, 2
A
1, 2, 3
Co-Simulation
A
1, 3
A3
Physics-Based Models
i3
* Physics, Fast/Mid/Slow Dynamics
* Economics, O&M
* High/Mid/Low Fidelity
Computer Science
* Multiphysics Simulation
* Optimization Algorithms
* Data-Based, Machine Learning
* High-/Mid-/Low-/Mixed-Fidelity Models
A
2, 3
A2
Co-Optimization
* Formal Mathematical Methods
* Multivariable-Constrained Optimization
* Nonlinear Models
* Low-/Mid-Fidelity Models
Microgrid Objectives
* Performance, Life Span
* Resiliency, Reliability
* Economics, Renewables
Predesign of Components
* Microgrid Components
i2
* Generators, Loads, Storage, Network
i1
IEEE Electrification - September 2021

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