BESS Grid Disconnection Using Virtual-Synchronous Generator Control

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Solution Overview

Problem

Battery energy storage systems (BESS) fail to provide a seamless transition when disconnecting or connecting to the electrical distribution system, leading to temporary blackouts due to slow switchgear response in grid failures, which can have adverse consequences for critical applications.

Innovation Solution

An electrical distribution system with a battery energy storage system and an electronic controller configured to implement a virtual-synchronous generator control mode, detecting voltage vector shifts to automatically disconnect the grid power source and switch to battery power within milliseconds, ensuring continuous supply to electrical loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional switchgear is used to disconnect the grid power source, then the system structure is simple, but the disconnection speed is too slow causing temporary blackouts

Engineering Contradiction:

Improvedisconnection speedVSAvoidsystem complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical switchgear with an electronic controller that implements virtual-synchronous generator control mode. This electronic control system detects grid failures and commands disconnection much faster than mechanical switchgear, achieving rapid transition to battery power without the speed limitations of mechanical moving parts.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters of the battery energy storage system by implementing virtual-synchronous generator control mode. This control mode enables the system to respond to grid failures with accelerated timing characteristics, transforming the response time parameter from seconds (conventional switchgear) to milliseconds (electronic control), thereby resolving the speed contradiction.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the switchgear disconnects rapidly to prevent blackouts, then the power supply continuity is improved, but the switchgear may fail to provide seamless transition in specific circumstances

Engineering Contradiction:

Improvepower supply continuityVSAvoidseamless transition

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies preliminary action by pre-configuring the battery energy storage system with virtual-synchronous generator control capabilities before grid failures occur. The system is prepared in advance to immediately assume power supply responsibilities, ensuring seamless transition without interruption. The electronic controller is pre-programmed with the control algorithm that enables instantaneous takeover when grid failure is detected.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces the virtual-synchronous generator control mode as an intermediary mechanism between the grid power source and the battery system. This control mode acts as a mediator that manages the transition smoothly, coordinating the disconnection of grid power with the simultaneous activation of battery power, thereby ensuring continuous and seamless power supply to electrical loads.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the BESS system is integrated with photovoltaic converters to increase autonomy, then the energy storage capability is improved, but the ability to provide seamless transition during disconnection is reduced

Engineering Contradiction:

Improveenergy storage capabilityVSAvoidtransition performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies universality by designing the electronic controller to implement virtual-synchronous generator control mode that can manage multiple power sources (grid power, battery power, and photovoltaic power) through a unified control algorithm. This multi-functional control approach ensures seamless transition capability is maintained regardless of which power source is active, resolving the contradiction between energy storage versatility and transition reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP4290736A1Devices and methods for disconnecting a grid power source from an electrical distribution system

Publication Date: 2023.12.13 SCHNEIDER ELECTRIC IND SAS

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AI summary

An electrical distribution system (2) is configured to supply electric power to an electric load (8) and comprises a feeder (6), a battery energy storage system (10), an electrical switchgear device (14) and an electronic controller. The switchgear device is configured to selectively connect the connection point to the feeder, wherein the electronic controller is configured to: - detect an electric fault representative of a power loss event on the grid power source, - upon detecting an electric fault, automatically open the electrical switchgear device to disconnect the grid power source from the feeder, - ensuring that the battery system supplies electric power to the electric load while operating in a virtual-synchronous generator control mode.