Electric Meter Service Limiting for Cold Load Pick-Up
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrical distribution networks are vulnerable to sudden increases in demand following an outage, leading to potential damage from cold load pick-up and further outages due to inrush currents when cold loads reconnect.
Innovation Solution
An electric meter with metrology, processing, and optional communications capabilities that enters a service limiter mode upon power restoration, managing power demand by controlling a service switch to prevent overload, using timers and thresholds to determine connection and disconnection from the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cold loads are reconnected to the electrical distribution network after an outage, then power supply to premises is restored, but inrush current damages power assets and devices
Solution Approach 1:
The electric meter detects power restoration after an outage and proactively enters service limiter mode before full power connection. This preliminary action limits the initial power delivery to prevent inrush current from damaging power assets, while still restoring power supply to premises gradually
Solution Approach 2:
The system changes the operational parameters of the electric meter by entering a special service limiter mode with modified thresholds and timing parameters. This mode adjusts the power delivery characteristics to limit inrush current while maintaining essential power supply, resolving the contradiction between restoration and damage prevention
2Reliability
If the electric meter enters service limiter mode upon power restoration, then cold load pick-up is managed and network stress is reduced, but power delivery to premises is limited
Solution Approach 1:
The service limiter mode operates periodically with defined entry and exit conditions. The meter monitors power delivery during outages and automatically enters service limiter mode upon restoration, applying limited power delivery for a predetermined period or until outage duration threshold is exceeded, then transitions to normal mode to restore full power
Solution Approach 2:
The electric meter dynamically adjusts its operational state based on detected outage conditions. The service limiter mode is not static but adapts based on outage duration, power delivery patterns, and predetermined thresholds, allowing the system to optimize between network protection and power delivery based on real-time conditions
3Reliability
If the service switch is controlled to disconnect premises when accumulated power exceeds threshold, then network overload is prevented, but continuous power supply is interrupted
Solution Approach 1:
The electric meter implements feedback control by continuously monitoring accumulated power delivery during service limiter mode. When the accumulated power exceeds the service limiter threshold, the meter controls the service switch to disconnect the premises. This feedback mechanism prevents network overload while managing power delivery to essential loads, balancing protection and continuity
Data Source
AI summary
Systems and methods for management of the connection of cold loads to an electrical distribution network are disclosed. One disclosed system for managing connection of cold loads to an electrical distribution network includes an electric meter configured to detect a restoration of power following an outage, and in response to detecting the restoration of power following the outage, restarting operation and entering a service limiter mode. The electric meter remains in the service limiter mode for a predetermined period of time. While in service limiter mode, the electric meter accumulates power and compares the accumulated power to a threshold value to determine whether to control a service switch to connect or disconnect one or more loads from an electrical distribution network. After another predetermined period of time, the electric meter may reconnect the one or more loads to the electrical distribution network and return to normal operations.