Cold Load Pickup Device Using Outage Duration Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Long power outages lead to 'cold load pickup' issues where energy storage loads like electric water heaters, HVAC systems, and vehicle charging stations draw maximum power upon restoration, overwhelming the grid and causing potential new outages or equipment stress, due to the lack of targeted and efficient startup management in conventional power grid systems.
Innovation Solution
A cold load pickup device with a microprocessor-based load controller that detects power restoration, determines the duration of a power outage, and applies a startup delay based on a stored curve to gradually restart energy storage loads, reducing initial power draw and mitigating grid strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power is restored instantaneously to all loads after a long power outage, then power delivery speed is improved, but grid overload and equipment stress increase due to simultaneous cold load pickup
Solution Approach 1:
The system performs preliminary detection of power outage duration and calculates appropriate startup delays before actually restarting loads. This preliminary action allows the system to prepare a staged restart sequence that prevents grid overload while maintaining relatively fast recovery time.
Solution Approach 2:
The system dynamically adjusts the startup delay for each load based on the detected power outage duration and the specific load type. Rather than using a fixed delay for all loads, the system optimizes each load's restart timing individually, balancing quick recovery with grid stability.
2Reliability
If power is restored sub-circuit by sub-circuit to limit power surges, then grid overload is reduced, but total recovery time increases and customer impact is negatively affected
Solution Approach 1:
The system segments the restart process into individual load-level stages rather than restoring entire sub-circuits sequentially. Each load is independently monitored and restarted at its optimal time, allowing parallel restart across multiple loads while still managing power surge levels.
Solution Approach 2:
The system changes the timing parameter for each load's startup based on the detected power outage duration and load characteristics. This parameter adjustment allows the system to optimize restart timing for each specific condition, achieving both fast recovery and grid stability.
3Productivity
If energy storage loads are restarted immediately after power restoration, then load functionality is restored quickly, but maximum power draw stresses the circuit and can cause premature equipment failures
Solution Approach 1:
The system performs preliminary detection of power outage duration and calculates appropriate startup delays before actually restarting loads. This preliminary action allows the system to prepare a staged restart sequence that prevents grid overload while maintaining relatively fast recovery time.
Solution Approach 2:
The system changes the timing parameter for each load's startup based on the detected power outage duration and load characteristics. This parameter adjustment allows the system to optimize restart timing for each specific condition, achieving both fast recovery and grid stability.
Data Source
AI summary
A cold load pickup device includes a load controller comprising a microprocessor or microcontroller. The device is programmed to detect restoration of power after a power outage on a circuit powering an electric load. A power outage time for the power outage is determined, and a startup delay for the electric load is determined based on the power outage time. A startup delay mechanism, such as a power relay operated by the load controller or switching of the load on/off by the load controller, is configured to apply the startup delay after the detected restoration of power before restarting the electric load. In some embodiments, the startup delay for the electric load is determined based on the power outage time and a startup delay versus power outage time curve stored in a non-volatile memory of the load controller.