DC Power Grid Fault Detection Using Predetermined Current Profiles
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Solution Overview
Problem
Conventional AC power grid systems are costly and inefficient, while DC power grid systems face challenges in control and protection due to rapid fault detection and response requirements, leading to safety concerns and high costs, especially with the integration of distributed resources and varying load conditions.
Innovation Solution
A power grid system that utilizes slow rates of change in current to enable early fault detection and isolation, incorporating a supply network with a protection device that compares current measurements to a predetermined pattern, and a load controller with a processor to manage energy storage and communication pulses for stable operation and fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If DC power grid systems are designed to respond quickly to fault conditions, then fault detection speed is improved, but system complexity and control difficulty increase
Solution Approach 1:
The patent changes the fundamental parameter of current behavior from rapid transients to slow rates of change. By designing the DC power grid system to operate with deliberately slowed current transitions, the system achieves fast fault detection capability without requiring complex control algorithms. The slow current changes create a stable operating baseline that simplifies fault detection while maintaining rapid response capability.
Solution Approach 2:
Instead of using fast-responding protection algorithms to detect faults in a rapidly changing DC system, the patent inverts the approach by slowing down the current changes and using this stability to enable simpler, more reliable fault detection. The system detects faults by monitoring deviations from the expected slow rate of change, rather than trying to keep up with rapid transients.
2Object-affected harmful factors
If inductance is added to lower di/dt of current, then system safety is improved, but hardware cost increases
Solution Approach 1:
The patent changes the operational parameter of current rate of change (di/dt) from high to low by incorporating inductance. This parameter change achieves two things: it improves system safety by limiting fault current magnitude and rate of rise, and it enables the use of lower current-rated hardware components, thereby offsetting the inductance cost with savings in other hardware specifications.
3Reliability
If conventional overcurrent protections are used, then fault protection is provided, but fault detection time is delayed
Solution Approach 1:
The patent implements preliminary action by establishing a known, predictable current profile (slow rate of change) before faults occur. This predetermined current behavior pattern allows the protection system to quickly identify faults as deviations from the expected pattern, eliminating the delay inherent in conventional overcurrent protections that must wait for current to rise to threshold levels.
Data Source
AI summary
This application discloses a system that may comprise at least a portion of a supply network. The system may further comprise a load controller that controls current flow with a current level of I1 into a load network that provides power to one or more loads from the at least a portion of the supply network according to a preprogrammed load curve. The system may also comprise a protection system that isolates the at least a portion of the supply network from the load controller in response to detecting a current pattern that is inconsistent with the preprogrammed load curve.