HVDC Transfer Bus Switching for Controlled DC Network Connection
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Solution Overview
Problem
Existing HVDC network systems face challenges in efficiently and cost-effectively connecting and disconnecting multiple DC networks while maintaining operational flexibility and safety, particularly when DC lines and converters are active and carrying non-zero voltage.
Innovation Solution
The solution involves a main bus system with transfer buses, current limiting devices, and high-speed switches to manage inrush currents and allow for controlled disconnection, using a combination of resistors, inductors, and bypass switches to limit transient currents and enable fast, reliable connections and disconnections without the need for full DC circuit breakers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HVDC breakers are used to connect and disconnect DC networks, then the reliability of fault current breaking is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent divides the switching function into multiple specialized components: disconnectors for isolation, transfer switches for connection operations, and current limiting devices for fault protection. Each component performs a specific function rather than requiring a single complex HVDC breaker to handle all operations.
Solution Approach 2:
The patent introduces a transfer bus as an intermediary component between DC networks. This transfer bus with associated switches and current limiting devices acts as a mediator that enables safe connection and disconnection operations without requiring full HVDC breaker capability at every switching point.
2Reliability
If HVDC breakers are deployed for network connection and disconnection, then the safety of operational personnel is improved, but the maintenance costs and operational complexity increase
Solution Approach 1:
The switching system is segmented into disconnectors for safe isolation and transfer switches for controlled connections. This segmentation allows operational personnel to perform simpler, more manageable operations rather than controlling complex HVDC breakers, reducing operational complexity while maintaining safety.
3Reliability
If full DC circuit breakers are used for all switching operations, then the current breaking capability is improved, but the space requirements and investment costs increase
Solution Approach 1:
The patent employs simpler, more cost-effective disconnectors and transfer switches with current limiting devices instead of expensive full DC circuit breakers for all operations. These components provide adequate functionality for connection and disconnection tasks while occupying less space and reducing investment costs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the number of high-voltage components, lowers space and maintenance costs, and allows for flexible network operations independent of the network state, while providing peak current suppression and controlled discharging, thus enhancing operational efficiency and reducing the reliance on expensive HVDC breakers.
Implementation Method 1
a current limiting device having a resistor and a parallel resistor bypass switch for bypassing said resistor
Data Source
AI summary
An arrangement for connecting and disconnecting DC networks includes a main bus for connecting a plurality of DC lines with each other. First and second DC lines are connected between first and second DC networks and the main bus via respective main switches. The DC networks contain a DC operating equipment, such as a converter, an energy storage device, a DC chopper, a DC cable, an energy source and/or a load. A transfer bus that is electrically connected to the main bus has a transfer bus disconnector for disconnecting the main bus from the transfer bus, a transfer switch, and a current limiting device with a resistor and a parallel resistor bypass switch. The first DC line is connected to the transfer bus via a first transfer disconnector and the second DC line is connected to the transfer bus via a second transfer disconnector.