Pilot Protection for Renewable Energy Transmission Lines
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Solution Overview
Problem
Traditional relay protection methods for renewable energy power stations, such as differential and distance protection, are less sensitive and slower in responding to faults due to the distinct characteristics of short-circuit currents from renewable energy sources like wind and photovoltaic power, leading to potential maloperations as the scale of renewable energy integration increases.
Innovation Solution
A pilot protection method based on current waveform similarity is implemented, where identical relay protection devices on both sides of the transmission line measure and compare correlation coefficients of three-phase currents to determine fault types, utilizing the unique transient characteristics of short-circuit currents to enable rapid and reliable fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional differential protection and distance protection based on power frequency components are applied to transmission lines of renewable energy power stations, then the protection system can operate with conventional principles, but the sensitivity and response speed deteriorate due to the distinct characteristics of short-circuit currents from renewable energy sources
Solution Approach 1:
The patent changes the protection principle from traditional power frequency component-based methods to wavelet transform-based current waveform analysis. This parameter change enables the protection system to capture transient features of short-circuit currents from renewable energy sources, significantly improving fault detection sensitivity and response speed while maintaining protection reliability.
Solution Approach 2:
The patent replaces traditional electromagnetic protection mechanisms with a computational approach using wavelet transform and correlation coefficient calculation. This substitution allows the system to analyze current waveforms in the time-frequency domain, enabling accurate detection of faults despite the atypical current characteristics from renewable energy sources.
2Device complexity
If traditional relay protection methods are used, then the system structure remains simple and conventional, but the response speed and fault detection capability worsen when dealing with renewable energy power station transmission lines
Solution Approach 1:
The patent introduces dynamic waveform analysis using wavelet transform that adapts to the transient characteristics of renewable energy short-circuit currents. The correlation coefficient calculation dynamically compares current waveforms in real-time, enabling rapid fault detection and response while maintaining manageable system complexity through standardized implementation procedures.
3Adaptability or versatility
If traditional protection principles are applied to transmission lines with increasing renewable energy capacity, then existing protection frameworks can be maintained, but the risk of maloperation increases due to the unique short-circuit current characteristics
Solution Approach 1:
The patent develops a universal protection method based on wavelet transform and correlation coefficient analysis that can handle various types of faults and renewable energy sources (wind, photovoltaic, etc.). This multi-functional approach improves protection accuracy by adapting to different short-circuit current characteristics while maintaining a unified protection framework that reduces maloperation risks.
Data Source
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AI summary
This Invention discloses a pilot protection method for transmission line of renewable energy power station based on current waveform similarity, comprising: Mount identical relay protection devices respectively on sides M and N of a transmission line of the renewable energy power station, with each protection device independently measuring the three-phase current of its own side, and acquiring the three-phase current of the opposite side by means of a communication channel; each set of relay protection device calculates correlation coefficients according to the same-phase current sampled values within the same time window at the same time on the own side and the opposite side; and each set of relay protection device judges whether there is a fault inside the internal transmission line of the renewable energy power station based on the comparison between the set value and the calculated correlation coefficient of current of each phase and then enables corresponding protective measures according to the fault type. The method can provide transmission lines of various types of renewable energy power stations having different capacity sizes with pilot protection of a new principle which has high reliability and sensitivity and a good speed.