Power Switching Control Device for Transient Voltage Suppression
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Solution Overview
Problem
Conventional power switching control devices fail to effectively suppress transient voltage or current generation due to variations in load-side voltage after interrupting current, as they assume constant load-side voltage behavior, leading to mismatched circuit-breaker gap voltage estimates and inadequate control during subsequent closing phases.
Innovation Solution
A power switching control device with a voltage measurement unit, estimation unit, and target closing-time calculation unit that measures and estimates power-supply and load-side voltages, calculates a target closing-time domain to ensure the circuit breaker can be closed within a predetermined voltage range, and delays the closing time in subsequent phases to account for voltage variations caused by preceding phase closures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional power switching control device uses a fixed target closing time calculated based on voltage estimates right after current interruption, then the control method is simple, but the circuit breaker cannot be reliably closed within the allowable voltage range in subsequent phases due to load-side voltage variations
Solution Approach 1:
The patent applies dynamics by transitioning from a static voltage estimation (fixed at current interruption moment) to a dynamic voltage estimation that evolves over time. The voltage estimation unit continuously updates the load-side voltage estimate based on the measured voltage waveform and estimated frequency, allowing the target closing time to be dynamically adjusted according to actual voltage conditions in each phase.
Solution Approach 2:
The patent applies preliminary action by performing voltage estimation and target closing time calculation in advance before the actual closing operation. The system estimates the voltage waveform characteristics and predicts the optimal closing time beforehand, allowing the closing control to be executed precisely when the voltage is within the allowable range.
2Object-affected harmful factors
If the power switching control device calculates target closing time based on voltage estimates right after current interruption, then the calculation is straightforward, but transient voltage or current cannot be sufficiently suppressed due to voltage variations in subsequent phases
Solution Approach 1:
The patent applies feedback by using the measured load-side voltage waveform to continuously update the voltage estimation. The voltage estimation unit compares the measured voltage with the estimated voltage waveform, adjusts the estimated frequency and phase based on the actual waveform characteristics, and recalculates the target closing time to ensure accurate prediction of the optimal closing moment.
Solution Approach 2:
The patent applies parameter changes by adjusting the estimated frequency and phase of the voltage waveform based on actual measurements. The system changes the voltage estimation parameters (frequency, phase, amplitude) to match the actual voltage conditions in each phase, thereby accurately determining the target closing time that suppresses transient voltage or current.
Data Source
AI summary
A power switching control device and a closing control method thereof that can suppress generation of a transient voltage or current that is possibly caused by a variation in a load-side voltage after interrupting a current are obtained. A circuit-breaker-gap-voltage estimate value at and after a present time is calculated based on a power-supply-side voltage estimate value and a load-side voltage estimate value at and after the present time, a target closing-time domain from a closing controllable time to a closing control limit time in which a circuit breaker can be closed at a timing when an absolute value of the circuit-breaker-gap-voltage estimate value falls within a preset allowable range is calculated based on this circuit-breaker-gap-voltage estimate value, and the closing controllable time is delayed by a preset delay time in a case of a subsequent closing phase of a second or later closing phase.