GFM
Grid-forming inverter
An inverter controlled as a voltage source that sets its own voltage and frequency, able to energise and hold up an island.
SLD
Functional block · MRIC
Microgrid restoration inrush-reserve check
Functional block · Microgrids
An independently authored application reference. The drawing shows the named function or circuit relationship; use the project legend and selected equipment documentation for its drafting form and connections.
Browse this installation focusIn plain English
What this block does
Identifies the declared source margin considered before introducing the assigned load or transformer.
A simple example
In a microgrid recovering from a blackout, an available grid-forming source can establish the assigned island reference before compatible generation and eligible load groups are introduced under the validated restoration strategy. For this reference, the drawing identifies “Available margin and connection demand” at the input and “Restoration reserve check” at the output. Transient performance needs validated studies.
What the drawings help you do
Start at the named input: Available margin and connection demand. Identify its source device or document and the state represented on the drawing. Follow the named output: Restoration reserve check. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Available margin and connection demand
- Output
- Restoration reserve check
- Application reference
- An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.
Read the source: Avista Shared Energy Economy microgrid protection and control case study
Schematic · MRIC
What it represents
Identifies the declared source margin considered before introducing the assigned load or transformer. Black-start and restoration control coordinates the establishment of an electrical reference and the gradual return of assigned resources and loads. A dead system, an available starting source and a successful load restoration are distinct states.
In a microgrid recovering from a blackout, an available grid-forming source can establish the assigned island reference before compatible generation and eligible load groups are introduced under the validated restoration strategy. For this reference, the drawing identifies “Available margin and connection demand” at the input and “Restoration reserve check” at the output. Transient performance needs validated studies.
Show the prerequisites and confirmation at each control boundary. These original explanatory blocks are not an operating procedure; energization, protection, transformer inrush and motor reacceleration require system-level validation. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation.
How to read it
- Start at the named input: Available margin and connection demand. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Restoration reserve check. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Transient performance needs validated studies.
- Show the prerequisites and confirmation at each control boundary. These original explanatory blocks are not an operating procedure; energization, protection, transformer inrush and motor reacceleration require system-level validation.
Information to show or reference
- Label the source and connection reference for available margin and connection demand.
- Identify the destination and defined state of restoration reserve check.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Transient performance needs validated studies.
A distinction that matters
Transient performance needs validated studies. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Avista Shared Energy Economy microgrid protection and control case study
Public technical context for microgrid black-start and restoration controls. Storage, protection, black start, load restoration and coordinated island operation. The application text and educational graphic are independently authored; the publisher does not certify this representation.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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Functional block
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