Distance Protection Relay Adaptation for Remote Infeed Reactance
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Solution Overview
Problem
Distance protection systems in electrical power systems face challenges in accurately detecting fault locations due to variations in fault resistance and remote infeed, leading to potential maloperations and insecurity in relay operations.
Innovation Solution
The method involves receiving current and voltage measurements at a distance protection device, computing a first impedance, determining a fault location, computing a second impedance, re-determining the fault location, and controlling the distance protection system. This process includes adapting the relay operation using a two-port equivalent model and adjusting the tilt angle of the reactive reach boundary to improve dependability and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the distance protection uses conventional impedance measurement methods, then the relay operation is simple and fast, but the fault location detection accuracy deteriorates due to reactance effect from remote infeed and fault resistance
Solution Approach 1:
The patent applies preliminary action by pre-calculating the tilt angle of the reactive reach boundary based on system parameters before a fault occurs. This pre-computed angle is stored and immediately applied during fault conditions, eliminating the need for complex real-time calculations while maintaining high measurement precision in fault location detection.
Solution Approach 2:
The patent introduces an intermediary parameter - the tilt angle of the reactive reach boundary - that mediates between the simple impedance measurement and the complex reactance effects. This angle serves as a correction factor that adjusts the impedance measurement to compensate for remote infeed and fault resistance without requiring full complex modeling during fault conditions.
2Reliability
If the distance protection adapts to variations in fault resistance and remote infeed, then the dependability and security improve, but the computational complexity increases
Solution Approach 1:
The patent performs preliminary calculations of the tilt angle based on pre-fault system conditions and stores these values for immediate use during faults. This approach ensures reliable adaptation to varying fault conditions while avoiding complex real-time computations, thus maintaining high dependability without excessive computational burden.
Solution Approach 2:
The patent changes the parameter used for fault detection from the conventional fixed impedance threshold to a dynamic tilt angle that adapts to system conditions. This parameter transformation allows the relay to maintain high security and dependability across varying fault resistance and remote infeed conditions while using simplified computational formulas.
3Ease of operation
If the distance protection uses a fixed impedance threshold, then the relay operation is simple and fast, but the selectivity deteriorates under varying fault conditions
Solution Approach 1:
The patent transforms the fixed impedance threshold into a dynamic reactive reach boundary defined by the tilt angle. This dynamic boundary automatically adapts to varying fault conditions such as changes in fault resistance and remote infeed, maintaining high selectivity while keeping the relay operation simple through the use of straightforward angle-based comparisons rather than complex adaptive algorithms.
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.