Microgrid Design: Building Resilient Local Energy Networks

What is a Microgrid?

A microgrid is a localized energy system that can operate in parallel with the main utility grid or independently (islanded). It typically integrates solar PV, battery storage, backup generators, and intelligent controls to serve a defined load cluster.

Operating Modes

Grid-Connected: Exchanges power with utility. Can export surplus solar, import during deficits. Frequency/voltage set by grid.
Islanded: Fully autonomous. BESS or generator sets frequency and voltage reference. Requires seamless transition capability.

Three-Level Control Architecture

Primary Control: Droop control — instant power sharing among parallel inverters (milliseconds).
Secondary Control: Restores frequency/voltage to nominal after load changes (seconds).
Tertiary Control: Economic dispatch — optimizes generation mix for lowest cost (minutes).

BESS Sizing for Microgrids

Critical loads must be served during islanding. Size BESS to cover worst-case solar deficit period. Rule of thumb: 1.5-2× daily critical load for reliable islanding with solar.

What is a Microgrid?

Operating Modes

Grid-Connected: Exchanges power with utility. Can export surplus solar, import during deficits. Frequency/voltage set by grid.
Islanded: Fully autonomous. BESS or generator sets frequency and voltage reference. Requires seamless transition capability.

Three-Level Control Architecture

Primary Control: Droop control — instant power sharing among parallel inverters (milliseconds).
Secondary Control: Restores frequency/voltage to nominal after load changes (seconds).
Tertiary Control: Economic dispatch — optimizes generation mix for lowest cost (minutes).

BESS Sizing for Microgrids

Critical loads must be served during islanding. Size BESS to cover worst-case solar deficit period. Rule of thumb: 1.5-2× daily critical load for reliable islanding with solar.