On-Load Tap Changer Timing for Current Zero-Crossing Switching
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Solution Overview
Problem
Existing on-load tap-changer actuation methods do not adequately account for the mechanical inertia of the drive train, leading to arcs being generated during the switching process, which can damage vacuum interrupters.
Innovation Solution
A method and device that utilize a control device and sensor to detect current profiles, predict future current zero crossings, and adjust the actuation timing of the on-load tap-changer to align with these zero crossings, thereby minimizing the temporal offset caused by the drive train mechanics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the on-load tap-changer is actuated immediately after receiving the switching command, then the switching response time is short, but arcs are generated during switching which can damage vacuum interrupters
Solution Approach 1:
The control device calculates the optimal actuation start time in advance by considering the drive train's mechanical inertia and the current zero-crossing timing. This preliminary calculation allows the system to initiate actuation at the precise moment that aligns with current zero-crossing, preventing arc generation while maintaining fast switching response.
Solution Approach 2:
The control device continuously monitors the current profile and uses this feedback to dynamically adjust the actuation timing. By detecting the actual current waveform and calculating the upcoming zero-crossing time, the system adapts the actuation start time to ensure synchronization with current zero-crossing, thereby eliminating arcs.
2Object-affected harmful factors
If the actuation timing is adjusted to align with current zero crossings, then arc burning time is reduced, but the control system complexity increases
Solution Approach 1:
The control device autonomously calculates the optimal actuation timing by itself, using the detected current profile and known drive train characteristics. The system determines the required start time considering mechanical inertia and predicts the zero-crossing alignment, eliminating the need for external timing coordination or complex external control systems.
Solution Approach 2:
The control device performs preliminary calculation of the actuation start time by adding the temporal offset (accounting for mechanical inertia) to the detected current zero-crossing time. This advance calculation simplifies the real-time control by pre-determining the optimal timing before actuation begins.
Data Source
AI summary
A method for actuating an on-load tap-changer with a drive, a sensor and a control device is provided. The control device receives a switching command to actuate the on-load tap-changer. A starting time at which the switching command to actuate the on-load tap-changer was received in the current profile is determined. A temporal offset is added to the starting time to determine a time at which the actuation starts. A time of a next current zero crossing after the time at which the actuation starts is determined. A temporal difference between the time at which the actuation starts and the time of the next current zero crossing is determined. The temporal difference to the starting time in order to determine a new starting time for the actuation therefrom is determined and the actuation of the on-load tap-changer is started at the new starting time by the drive.