Trapped Charge Estimation for Power Line Reclosure
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Solution Overview
Problem
In electric power delivery systems, trapped charge on power lines can cause voltage transients when circuit breakers are reclosed, potentially leading to persistent faults due to exceeding designed operating conditions.
Innovation Solution
Intelligent electronic devices (IEDs) estimate the trapped charge on power lines using voltage measurements and control the circuit breaker operation to minimize these transients by determining optimal closing points-on-wave for each phase, reducing the voltage differences between disconnected and online power system voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If circuit breaker is reclosed after fault clearance, then power delivery is restored, but voltage transients occur due to trapped charge causing potential persistent faults
Solution Approach 1:
The system performs preliminary measurement of trapped charge on the power line before reclosing the circuit breaker. Based on the measured trapped charge, the optimal reclosing time is calculated in advance, allowing the system to restore power delivery while avoiding voltage transients by closing at the precise moment when trapped charge equals system voltage.
Solution Approach 2:
The system continuously monitors voltage measurements on the power line to determine trapped charge levels. This feedback information is used to dynamically adjust and determine the optimal reclosing time, ensuring that the circuit breaker closes when voltage conditions are favorable, thereby restoring power without causing harmful transients.
2Object-affected harmful factors
If trapped charge is measured and optimal reclosing time is determined, then voltage transients are minimized, but system complexity increases
Solution Approach 1:
The intelligent electronic device performs self-measurement of trapped charge using its own voltage measurement capabilities. The system determines its own optimal reclosing time based on internal calculations, eliminating the need for external measurement devices or complex coordination with other system components, thereby minimizing the increase in system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces transient voltages and minimizes the risk of faults becoming persistent, ensuring safe and reliable power system operation by accurately estimating and managing trapped charge during reclosure processes.
Implementation Method 1
trapped charge on a power line... obtaining a measurement of a voltage on the power line... determining an amount of trapped charge on the power line based on the measurement of the voltage
Data Source
AI summary
Systems and methods to estimate trapped charge for a controlled automatic reclose are described herein. For example, an intelligent electronic device (IED) may calculate an analog amount of trapped charge of each phase of a power line based on voltage measurements of the power line. The IED may close a switching device of each phase at a time corresponding to a point-on-wave associated with the analog amount of trapped charge of the respective phase.