Microgrid PCC Switching for Islanding Risk Control

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Solution Overview

Problem

The complexity of power management, protection, and islanding detection increases when multiple points of common coupling (PCCs) are used in microgrids, making it challenging to avoid islanding while maintaining reliability.

Innovation Solution

A microgrid system that connects via only one PCC but can switch to another PCC when islanding is detected, using a control unit to manage power flow and switch positions to maintain stability without activating all available PCCs simultaneously.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple PCCs are used in microgrids, then grid reliability is improved, but control complexity increases

Engineering Contradiction:
Improvegrid reliabilityVSAvoidcontrol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the PCC functionality into a primary PCC for normal operation and a secondary PCC for backup. This segmentation allows the system to maintain simplicity by using only one active connection while having a standby option, thus improving reliability without permanently increasing control complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary configuration of multiple PCC connections but keeps them inactive except for the primary one. The secondary PCC is prepared in advance as a backup option, allowing quick switching upon detection of islanding conditions without requiring complex real-time control of multiple active connections.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If multiple PCCs are activated simultaneously, then risk of islanding is reduced, but power management complexity increases

Engineering Contradiction:
Improverisk of islandingVSAvoidpower management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Instead of activating all available PCCs simultaneously, the system activates only the necessary primary PCC for normal operation and keeps the secondary PCC in standby mode. This partial activation approach provides sufficient protection against islanding while avoiding the excessive complexity of managing multiple active power connections.

Inventive Principle:
Principle #16Partial or excessive action

3Stability of the object's composition

If all available PCCs are kept active, then grid stability is improved, but operational complexity increases

Engineering Contradiction:
Improvegrid stabilityVSAvoidoperational complexity
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent segments the PCC operations into distinct primary and secondary roles with clear functional separation. The primary PCC handles normal grid connection while the secondary PCC remains in standby, providing grid stability through role specialization rather than through complex coordination of multiple equally-active connections.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3042429B1Microgrid with redundant points of common coupling and control method for it, to reduce risk of microgrid's islanding
Publication Date: 2024.11.06 HITACHI ENERGY LTD
  • EP3042429B1 patent drawingFigure 1~4
  • EP3042429B1 patent drawingFigure 5~7

AI summary

The present disclosure relates to a microgrid 100 connecting at least one distributed electricity generator 130. The microgrid comprises a first switch 111 configured for, in a closed position, connecting the microgrid to a first network line 121 at a first point of common coupling (PCC) 141 and for, in an open position, disconnecting the microgrid from the first network line at the first PCC; a second switch 112 configured for, in a closed position, connecting the microgrid to a second network line 122 at a second PCC 142, and for, in an open position, disconnecting the microgrid from the second network line at the second PCC; and a control unit 150 configured for, when an islanding event has been detected when the second switch is in its closed position and the first switch is in its open position, acting to close the first switch, bringing it to its closed position.