Phase Selection Method for Wind Farm Power Grids
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Solution Overview
Problem
Existing methods for phase selection in power line fault detection are inadequate, particularly in wind farm connected power grids, where non-linear behaviors complicate the reliable identification of faults using single phase tripping and change of phase currents or voltages.
Innovation Solution
A method that determines transient energies and energy ratios for phase-to-ground and phase-to-phase loops based on voltage and current measurements, allowing for improved phase selection by comparing these ratios against thresholds to identify fault types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phase selection is based on change of phase currents, then the method is simple to implement, but it cannot provide full selectivity in wind farm connected power grids
Solution Approach 1:
The patent changes the parameter used for phase selection from phase current change to transient energy calculation. By computing transient energy based on voltage and current measurements and comparing energy ratios between different phases, the method achieves reliable phase selection in wind farm connected power grids while maintaining operational simplicity through automated energy calculation and threshold comparison
2Adaptability or versatility
If phase selection is based on change of phase voltages, then it might work for wind farm connected grids, but it does not work well in strong system conditions
Solution Approach 1:
The patent creates a universal phase selection method that works across different system conditions (both weak and strong sources) by using transient energy calculation. The method calculates transient energy for all phases and compares energy ratios, providing a unified approach that adapts to various system conditions without requiring separate methods for different operating scenarios
3Stability of the object's composition
If single phase tripping is used, then the overall power system stability can be maintained, but reliable fault detection and isolation becomes challenging
Solution Approach 1:
The patent replaces traditional mechanical/protective relay-based fault detection with an automated transient energy calculation method. By computing transient energy from voltage and current measurements and using energy ratio comparison, the system achieves reliable fault detection and selective tripping, enabling single phase tripping to maintain stability while improving detection reliability through sophisticated energy-based analysis
Data Source
AI summary
A method for determining a type of fault in a power line is provided. The method comprises obtaining voltage and current measurements at a measurement point of the power line. The method further comprises determining transient energies over a first time period for a number of phase-to-ground loops and phase-to-phase loops of the power line, based on the obtained voltage and current measurements. The method further comprises determining transient energy ratios for the phase-to-ground loops and phase-to-phase loops. The method further comprises comparing the transient energy ratios with thresholds corresponding to the phase-to-ground loops or phase-to-phase loops and determining a type of fault based on the comparison.