Distance Protection Adaptation for Remote Infeed Reactance Effects
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Solution Overview
Problem
Distance protection relays in electrical power systems face challenges in accurately determining fault locations due to the influence of reactance effects and fault resistance, particularly in systems with remote infeed and non-homogeneous configurations, leading to unreliable and insecure relay operations.
Innovation Solution
A method and device for controlling distance protection systems that adapt relay operations by computing and re-determining fault locations using impedance measurements, considering system homogeneity and employing a two-port equivalent model to compensate for reactance effects, allowing for reliable fault detection and prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If distance protection relay uses traditional impedance measurement method, then the relay operation is simple, but the fault location determination accuracy deteriorates due to reactance effects and fault resistance
Solution Approach 1:
The patent changes the measurement parameters by computing apparent impedance using voltage and current measurements, then iteratively refines the fault location estimate by updating impedance calculations. This transforms the simple but inaccurate traditional method into an adaptive process that maintains operational simplicity while improving measurement precision through parameter refinement.
Solution Approach 2:
The patent implements feedback by using the initially determined fault location to compute apparent impedance, then using this impedance information to re-determine and refine the fault location. This iterative feedback loop continuously improves measurement accuracy while building upon the initial simple measurement, resolving the contradiction between operational simplicity and measurement precision.
2Device complexity
If distance protection relay assumes network homogeneity, then the calculation is simplified, but the applicability deteriorates in systems with converter interfaced renewable power plants
Solution Approach 1:
The patent applies dynamics by making the impedance calculation adaptive rather than static. Instead of assuming fixed network homogeneity, the method dynamically computes apparent impedance based on actual voltage and current measurements at the relay location, allowing the calculation to automatically adapt to different system configurations including converter interfaced renewable power plants without increasing fundamental calculation complexity.
3Loss of time
If distance protection relay uses single impedance measurement, then the operation is fast, but the reliability deteriorates due to reactance effect deviations
Solution Approach 1:
The patent applies preliminary action by first computing an initial fault location and apparent impedance quickly from voltage and current measurements. This preliminary result is then used to guide subsequent refinement steps, allowing the system to establish a reliable baseline rapidly while having the option to improve accuracy if time permits and conditions warrant.
Solution Approach 2:
The patent implements partial action by performing iterative impedance recalculations only when necessary to improve accuracy. The method can stop after the initial fast measurement if reliability requirements are met, or continue with additional refinement iterations when higher reliability is needed, allowing flexible balancing of speed and reliability based on specific operational requirements.
Data Source
AI summary
The present disclosure relates to a method for controlling a distance protection system, as well as a respective device and system for performing the method. Measurements are received. The measurements comprise current and/or voltage measurements at a first position along a transmission line for an electrical power system. A first impedance is computed from the received measurements. A fault location is determined from the computed first impedance and a first impedance boundary. Responsive to the determined fault location, a second impedance is computed. The fault location is redetermined from the computed second impedance and the first impedance boundary. The distance protection system is controlled based on the determined fault location or the re-determined fault location.