Solid-State DC Protection via Preliminary Isolation
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Solution Overview
Problem
Conventional DC distribution system protection systems face challenges in reducing hardware requirements, minimizing fault current interruption stress, and enhancing fault location accuracy, as they often require interrupting high magnitude fault currents and rely on limited initial measurements for fault determination.
Innovation Solution
The proposed solution involves a protection system with a solid-state switching device, galvanic isolation switching device, and a controller that isolates power converters from faults by opening the solid-state switching device during low current conditions, allowing for more accurate fault location determination using measurements from a DC link capacitor's discharging current, and utilizing a central control system for aggregated fault location information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional protection systems interrupt high magnitude fault current to isolate faults, then fault isolation is achieved, but stress on power electronics increases and hardware requirements increase
Solution Approach 1:
The protection system performs preliminary actions by detecting faults and opening the solid-state switching device before the fault current reaches its peak magnitude. The system anticipates the fault current surge and acts preemptively during the low current period, thereby isolating the fault without subjecting power electronics to high stress interruption conditions
Solution Approach 2:
The solid-state switching device serves as an intermediary element that enables fault isolation without requiring conventional circuit breakers to interrupt high fault currents. This intermediary device allows the system to achieve fault isolation while avoiding the harmful stress of high magnitude current interruption on power electronic components
2Speed
If conventional protection systems use limited initial measurements for fault determination, then fast fault detection is achieved, but fault location accuracy decreases
Solution Approach 1:
The protection system maintains continuous useful action by collecting measurements throughout the entire fault isolation process rather than only during the initial detection phase. Measurements continue to be gathered as the solid-state switching device opens and the fault is isolated, ensuring that useful measurement data is collected continuously without interruption, thereby improving fault location accuracy while maintaining fast detection
Solution Approach 2:
The system performs preliminary fault detection using initial measurements for fast identification, then continues to collect additional measurements during the subsequent isolation phase. This preliminary action followed by continued measurement gathering allows the system to achieve both fast initial detection and high precision fault location through aggregated measurement data
3Loss of time
If protection systems collect measurements only during initial fault detection, then fast response is achieved, but measurement data completeness decreases
Solution Approach 1:
The protection system implements continuous useful action by maintaining measurement collection throughout the entire fault isolation sequence. Measurements are gathered during the initial detection phase and continue to be collected as the solid-state switching device opens and the fault is isolated, ensuring complete measurement data is obtained without sacrificing response time
Solution Approach 2:
The measurement collection process is made dynamic by adapting the measurement gathering to different phases of fault isolation. The system dynamically continues collecting measurements as conditions change during isolation, transforming a static single-phase measurement approach into a dynamic multi-phase measurement strategy that captures complete fault information
Data Source
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AI summary
Systems, methods, techniques and apparatuses of fault protection. One exemplary embodiment is a protection system (100) including a solid-state switching device (SSSD), a galvanic isolation switching device (GISD), and a controller (127). The solid-state switching device is coupled between a switch arrangement (111) of a power converter (110) and a direct current (DC) link capacitor (114) of the power converter. The galvanic isolation switching device (GISD) is coupled between the DC link capacitor (114) and a DC network (130). The controller (127) is structured to determine a fault is occurring within the DC network, open the solid-state switching device (SSSD) in response to determining the fault is occurring, receive a measurement (125) corresponding to an electrical characteristic of a fault current flowing through the galvanic isolation switching device (GISD) while the solid-state switching device (SSSD) is open, and determine a location of the fault based on the received measurement.