Dynamic Under-Frequency Load Shedding Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional load shedding systems in electrical power systems face instability due to rapid frequency changes, leading to potential frequency overshoot and system outages, especially with high penetration of volatile renewable energy sources, as they rely on fixed frequency thresholds without considering the rate of change of frequency.
Innovation Solution
A method and device that monitor both the frequency and its rate of change to generate control signals for load disconnection, using a frequency stability parameter to split existing stages into sub-stages, allowing for more gradual load shedding and adapting to power imbalances, thereby reducing the risk of frequency overshoot and improving system response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amount of load disconnected per stage exceeds the lost generation power, then the frequency can be restored faster, but the frequency may initially rise excessively and overshoot the upper limit of the safe frequency range causing generator disconnection
Solution Approach 1:
The invention segments the load disconnection process by introducing an intermediate frequency threshold between the initial frequency drop and the final restoration point. This creates multiple staged disconnection levels that prevent excessive frequency rise while maintaining restoration effectiveness
Solution Approach 2:
The invention implements dynamic frequency thresholds that adjust based on system conditions. The intermediate threshold is set adaptively to accommodate varying generation losses and load characteristics, allowing the system to respond flexibly to different imbalance scenarios
2Reliability
If the number of stages is increased to reduce load shed per stage, then frequency overshoot risk is reduced, but the response time to large events increases due to inherent latency of relay and circuit breaker operation
Solution Approach 1:
The invention applies partial action by disconnecting only the necessary portion of load at each threshold level rather than all load at once. The intermediate threshold triggers disconnection of a controlled portion of load, achieving stability without requiring excessive staging
3Device complexity
If conventional fixed frequency threshold systems are used, then the system structure is simple, but the system cannot adapt to rapid frequency changes and volatile renewable energy sources
Solution Approach 1:
The invention changes the parameter of frequency thresholds from fixed values to dynamic, adaptive thresholds. The intermediate threshold is configured based on system characteristics and can be adjusted to match varying operating conditions, enabling adaptation to renewable energy volatility
Data Source
AI summary
A method and device for load shedding in an electrical power system is provided. The electrical power system includes a device that electrically couples one or more load feeder lines to the electrical power system, where each load feeder lines provides power to consumers. The method includes: monitoring the electrical frequency of the electrical power system and monitoring a frequency stability parameter, which is dependent on a rate of change of the electrical frequency. A control signal is generated to disconnect at least one load feeder line by the device when the monitored frequency is at or below at least a predetermined disconnection frequency threshold and the monitored frequency stability parameter is at or has passed at least one predetermined frequency stability parameter threshold.