Network Impedance Measurement Without Reference Conductor
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Solution Overview
Problem
Measuring network impedance in medium and high-voltage electrical supply networks is challenging due to the absence of a reference conductor, which complicates the calculation of phase impedance in three-phase systems.
Innovation Solution
A device and method that utilize an excitation signal generating device, a load, a response signal measuring device, and a phase switching device to determine line impedance in multi-phase networks by switching between concatenated phase pairs, allowing for the measurement of network impedance without a reference conductor, using power electronics switches like IGBTs and TRIACs for asynchronous switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring system is implemented at medium and high voltage level, then network impedance measurement capability is improved, but device complexity increases due to missing reference conductor
Solution Approach 1:
The patent segments the measurement task by measuring line-to-line voltages between different phase pairs separately, then combining these measurements to calculate phase impedances. This avoids the need for a reference conductor by breaking down the complex measurement into simpler bilateral measurements between phase pairs.
Solution Approach 2:
The patent uses line-to-line voltage measurements as an intermediary approach. Instead of directly measuring phase-to-neutral voltages (which require a reference conductor), it measures voltages between phases and uses these as intermediaries to calculate the desired phase impedances through mathematical relationships.
2Device complexity
If asynchronous switching is used to reduce electronic power components, then device complexity is reduced, but control precision may be affected
Solution Approach 1:
The patent employs periodic switching of the excitation signal across different phase pairs in an asynchronous manner. This periodic action allows the system to cycle through different measurement configurations, gathering sufficient data to calculate all phase impedances while using fewer electronic power components than synchronous switching would require.
Data Source
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AI summary
Device and method for measuring the network impedance of an electrical supply network, in particular a supply network in which no reference conductor is present or available, by providing an excitation signal to different interconnected phases, measuring a corresponding response signal and determining the network impedance from the different excitation signals and the different response signals of the different interconnected phases.