Live Line Voltage Transformer Metrological Testing
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Solution Overview
Problem
Existing methods for testing the metrological properties of voltage transformers, especially those for medium and high voltages, require disconnecting the transformers from the power network, leading to costly interruptions and inability to test under real operating conditions.
Innovation Solution
An online live line method using upstream and downstream voltage sensors with GNSS time stamping to calculate phase displacement and ratio errors of voltage transformers while they are in use, allowing for real-time analysis without disconnecting the transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage transformers are disconnected from the power network for testing, then metrological properties can be tested, but electricity delivery is interrupted and testing costs increase
Solution Approach 1:
The patent enables continuous testing of voltage transformers while they remain connected and operational in the power network. The testing process does not require disconnection or interruption of electricity delivery, allowing the transformer to continue its useful function while being tested. This resolves the contradiction by maintaining continuous operation during the measurement process.
2Measurement precision
If voltage transformers are disconnected for testing, then metrological properties can be measured, but the transformer cannot be tested under real operating conditions
Solution Approach 1:
The testing system operates continuously while the transformer is in its normal operating state, enabling measurements to be taken under real operating conditions including actual voltage levels, load currents, and environmental conditions. This eliminates the need to disconnect the transformer for testing.
Solution Approach 2:
The system measures metrological properties across a range of operating parameters including different voltage levels, load conditions, and secondary burdens. By varying these parameters during normal operation, the system can assess transformer performance under diverse real-world conditions rather than just under fixed test conditions.
3Measurement precision
If traditional testing methods are used, then metrological properties can be tested, but the process is disruptive and costly
Solution Approach 1:
The system eliminates the need for disruptive shutdowns and complex disconnection procedures by performing tests while the transformer remains connected and operational. This significantly reduces testing costs and simplifies the testing process.
Solution Approach 2:
The patent introduces intermediary measurement devices including voltage sensors, current sensors, and time synchronization systems that can be connected to the transformer without requiring disconnection. These intermediaries enable non-intrusive measurement of metrological properties during normal operation.
Data Source
AI summary
A real time live line method analyses metrological properties of a high voltage voltage transformer configured to transform an upstream voltage into a downstream voltage. The method comprises obtaining a series of upstream voltage data points during a first time period using an upstream voltage sensor; and attributing an upstream time stamp provided by an upstream global navigation satellite system—GNSS—signal receiver to each one of the series of upstream voltage data points to obtain a time-stamped series of upstream voltage data points. The method further comprises: obtaining a series of downstream voltage data points during the first time period using a downstream voltage sensor; and attributing a downstream time stamp provided by a downstream global navigation satellite system—GNSS—signal receiver to each one of the series of downstream voltage data points to obtain a time-stamped series of downstream voltage data points. The method further comprises: calculating a voltage transformer phase displacement error between the time-stamped series of upstream voltage data points and the time-stamped series of downstream voltage data points; and calculating a voltage transformer ratio error by comparing a rated ratio of the voltage transformer with a measured ratio determined using the time-stamped series of upstream voltage data points and the time-stamped series of downstream voltage data points.