HVDC Sub-Module Bypass Control for Controller Failure Protection
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Solution Overview
Problem
High voltage direct current (HVDC) systems face disconnection risks due to failures in sub-module controllers, which can lead to dangerous short circuits and capacitor damage, as existing failure diagnosis systems are inadequate in preventing such events.
Innovation Solution
A device and method for bypassing an HVDC sub-module, featuring a sub-module controller, voltage monitoring unit, and bypass switch driving unit that monitor capacitor voltage and control IGBTs and diodes to bypass energy storage, release, and switching operations, ensuring stable operation even when the sub-module controller fails, by duplicating the driving unit for bypassing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sub-module controller is used to monitor and control the sub-module, then the sub-module can be controlled according to system commands, but the system may disconnect when the controller fails
Solution Approach 1:
A bypass control unit is introduced as an intermediary component that can take over control when the sub-module controller fails. The bypass control unit monitors the controller status and activates the bypass switch when failure is detected, ensuring continuous system operation without disconnection.
Solution Approach 2:
The bypass circuit and bypass control unit are pre-configured and ready before controller failure occurs. The bypass switch is positioned and connected in advance, allowing immediate activation without waiting for repair or replacement of the failed controller.
2Reliability
If a bypass switch is added to protect the capacitor, then the capacitor can be protected from overvoltage, but the device complexity increases
Solution Approach 1:
The bypass control unit serves as an intelligent intermediary that manages the bypass switch activation. It monitors capacitor voltage through the voltage sensor and only activates the bypass switch when necessary, avoiding unnecessary complexity while providing effective protection.
Solution Approach 2:
The bypass control unit autonomously monitors capacitor voltage and activates the bypass switch when overvoltage is detected, without requiring external intervention. This self-service capability simplifies the overall system by making the protection mechanism automatic and independent.
3Reliability
If the bypass control unit monitors capacitor voltage continuously, then the capacitor can be protected from failure, but energy consumption increases
Solution Approach 1:
The voltage sensor periodically samples capacitor voltage at predetermined intervals rather than continuously monitoring. This periodic sampling approach maintains adequate protection while significantly reducing energy consumption compared to continuous monitoring.
Solution Approach 2:
The bypass control unit is configured with predetermined activation voltage thresholds. When voltage reaches these pre-set levels, the bypass switch is automatically activated without requiring continuous analysis, reducing the energy needed for voltage assessment while maintaining protection effectiveness.
Data Source
AI summary
A bypass device of an HVDC sub module according to the present invention comprises: a sub module for generating a voltage in an HVDC system; a bypass switch driving unit for driving a bypass switch located at an input terminal of the sub module; a sub module controller for monitoring a state of the sub module to transmit the monitored state to a system controller, and controlling the sub module and the bypass switch driving unit according to a command of the system controller; and a voltage monitoring unit for controlling the bypass switch driving unit by monitoring a voltage of a capacitor located in the sub module.