DC Bus Capacitor Bank Segmentation for Fault Isolation and Diagnostics
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Solution Overview
Problem
Current power supply apparatuses for electric systems face reliability issues due to parallel connection of storage capacitors, leading to potential failure of the entire capacitor bank and difficulty in fault diagnostics, especially in challenging environments like subsea installations, where maintenance is expensive and complex.
Innovation Solution
The power supply apparatus incorporates current limiters and capacitor dischargers, along with a control unit and sensor units, to manage charging and discharging of storage capacitors, allowing for fault isolation and advanced diagnostic capabilities, including threshold-based charging and capacitance testing to identify faulty capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If storage capacitors are connected in parallel to increase power supply capacity, then the power supply capability is improved, but the reliability deteriorates because a fault in one capacitor can be fed by remaining capacitors leading to complete failure
Solution Approach 1:
The patent divides the capacitor bank into independent modular units, each with its own current blocking device. This segmentation isolates faults to individual modules, preventing cascade failure while maintaining overall system power capacity through parallel operation of healthy modules.
Solution Approach 2:
Current blocking devices are introduced as intermediary components between the AC/DC converter and each capacitor, and between capacitors and the DC bus. These intermediaries prevent harmful current flow paths that would otherwise cause complete system failure when a capacitor faults.
2Device complexity
If traditional power supply apparatuses are used without individual capacitor protection, then the device complexity is reduced, but the diagnostic capability deteriorates making fault detection difficult
Solution Approach 1:
The control unit continuously monitors the state of each capacitor through sensor units and uses feedback signals to detect faults, track capacitor health, and trigger appropriate protection responses. This enables proactive maintenance and quick fault identification without significantly increasing system complexity.
Solution Approach 2:
The system performs self-diagnosis and self-protection through automated monitoring and control. When a capacitor faults, the control unit automatically detects the condition and isolates the faulty module without requiring external intervention, maintaining simple operation while providing advanced diagnostics.
3Reliability
If current limiters are added to control charging current for each capacitor, then the reliability is improved through better current management, but the device complexity increases
Solution Approach 1:
The control unit merges the functions of multiple current limiters into a single centralized control system that manages charging currents to all capacitors. This integration maintains the reliability benefits of individual current control while reducing the overall complexity compared to having independent current limiters for each capacitor.
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 configuration enhances operational reliability by isolating faulty capacitors and enabling effective diagnostic procedures, ensuring continuous power supply and reducing maintenance costs through automated fault detection and periodic checks.
Implementation Method 1
an AC/DC conversion unit (2) electrically connectable to an electric power source (10). Said conversion unit (2) is configured to receive an AC input voltage and provide in output a DC charging voltage
Implementation Method 2
a plurality of storage capacitors (C1, C2, ..., CN) operatively coupled to said conversion unit (2) to be charged in parallel by said conversion unit (2)
Implementation Method 3
a plurality of current blocking devices (D1, D2, ..., DN)... configured to allow corresponding feeding currents to flow from the storage capacitors to the electric loads and are configured to block currents having opposite directions
Data Source
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AI summary
A power supply apparatus for an electric system comprising: - an AC/DC conversion unit electrically connectable to an AC electric power source, said conversion unit being configured to receive an AC input voltage and provide in output a DC charging voltage; - a capacitor bank including a plurality of storage capacitors operatively coupled to said conversion unit to be charged in parallel by said conversion unit, each storage capacitor having a first terminal configured to receive a charging current provided by said AC/DC conversion unit; - a DC bus electrically connectable to one or more electric loads, said DC bus being configured to feed said electric loads with a DC feeding voltage; - a plurality of current blocking devices electrically connected between said capacitor bank and said DC bus.