Current Recording via Fourier Transform Time Alignment
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Solution Overview
Problem
Current differential protection systems face challenges in time synchronization due to errors in time management or loss of GPS signals, leading to inaccurate triggering of differential protection actions and difficulties in post-event analysis, as they primarily store instantaneous current values from local ends, which are not time-aligned and lack sufficient data for comprehensive analysis.
Innovation Solution
A current recording method that involves acquiring Fourier values of current data from multiple ends of a power line, time-aligning them based on transmission delays, and storing these values to facilitate continuous differential protection and enhance post-event analysis, reducing data storage and communication burdens by using Fourier transforms instead of instantaneous values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS timing products are installed for time synchronization, then time alignment accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a server as an intermediary that centralizes the time alignment function. Instead of each protection device needing GPS timing products, the server performs time alignment on current data received from multiple ends, acting as a mediator that eliminates the need for complex local timing devices at each endpoint.
Solution Approach 2:
The time alignment function is extracted from the local protection devices and relocated to a centralized server. This separates the time synchronization requirement from the individual protection devices, allowing them to operate without GPS timing products while the server handles the complex time alignment task centrally.
2Loss of information
If instantaneous current values are stored for post-event analysis, then analysis data completeness is improved, but storage requirements increase
Solution Approach 1:
The patent transforms the representation of current data from instantaneous values to Fourier spectrum parameters. By changing the parameter form from time-domain instantaneous values to frequency-domain Fourier coefficients, the system maintains essential current characteristics for analysis while significantly reducing the storage quantity required.
Solution Approach 2:
The patent extracts only the essential spectral information needed for post-event analysis rather than storing complete instantaneous current waveforms. By taking out only the critical Fourier parameters that characterize the current signal, the system achieves adequate analysis capability with reduced storage requirements.
3Quantity of substance
If Fourier transforms are used to reduce data storage, then storage requirements are reduced, but measurement precision may be affected
Solution Approach 1:
The patent applies Fourier transformation to convert current data from time-domain instantaneous values to frequency-domain spectral parameters. This parameter transformation reduces the storage burden while preserving the essential characteristics of the current signal needed for protection and analysis functions.
4Measurement precision
If time alignment is performed using transmission delay compensation, then differential protection accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary time alignment by compensating for transmission delays before conducting differential protection calculations. By pre-aligning the current data from different ends based on known transmission delays, the system simplifies the subsequent protection logic while maintaining high accuracy in differential current comparison.
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
Ensures continuous and accurate differential protection by maintaining data synchronization without GPS synchronization, facilitates efficient post-event analysis, and reduces storage and communication requirements by using Fourier values, thereby improving fault detection and analysis capabilities.
Implementation Method 1
acquiring a first current Fourier value, the first current Fourier value being a Fourier value acquired by Fourier transforming an instantaneous value of current
Data Source
AI summary
It is provided a current recording method, a current recording device and a current recording system by the embodiments of this disclosure. The current recording method comprises: acquiring a first current Fourier value, the first current Fourier value being a Fourier value acquired by Fourier transforming an instantaneous value of current at a first end of a power line; acquiring a second current Fourier value, the second current Fourier value being a Fourier value acquired by Fourier transforming an instantaneous value of current at a second end of the power line; time-alignment the first current Fourier value and the second current Fourier value, based on a first transmission delay for acquiring the first current Fourier value and a second transmission delay for acquiring the second current Fourier value; storing the aligned first current Fourier value and second current Fourier value into a storage.