Adaptive Distance Protection Ground Potential Rise Depth Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ground distance relays in high voltage electrical substations are prone to misoperation due to the neglect of ground resistance between the substation ground grid and true remote earth, leading to inaccurate calculations of apparent impedance during faults.
Innovation Solution
The adaptive distance protection system measures the ground potential rise (GPR) between the ground grid and true remote earth, using this measurement to accurately calculate the apparent impedance of transmission lines, thereby reducing the risk of misoperation and improving fault location logic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional ground distance relays neglect ground resistance between the ground grid and true remote earth, then the device complexity is reduced, but the measurement precision of apparent impedance deteriorates
Solution Approach 1:
The patent introduces an intermediary measurement system consisting of a potential transformer and ground rod that measures ground potential rise (GPR) between the ground grid and true remote earth. This intermediary measurement allows the relay to compensate for ground resistance effects by subtracting the measured GPR from the phase voltage, thereby improving apparent impedance measurement accuracy without significantly increasing overall system complexity
Solution Approach 2:
The patent changes the reference parameter for voltage measurement from ground grid potential to true remote earth potential by measuring and compensating for GPR. This parameter transformation allows the relay to calculate apparent impedance using voltages referenced to true ground, eliminating the measurement error caused by ground resistance while maintaining practical system complexity
2Ease of operation
If ground resistance is ignored in calculations, then the ease of operation is improved, but the reliability of relay operation deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the measured ground potential rise (GPR) is continuously fed back to the relay calculation logic. The relay uses this feedback information to compensate for ground resistance effects by adjusting the voltage reference, thereby improving relay operation reliability while maintaining ease of operation through automated compensation rather than complex manual calculations
3Ease of operation
If voltage measurements are referenced to the ground grid, then the ease of operation is improved, but the measurement precision deteriorates due to ground potential rise
Solution Approach 1:
The patent introduces an intermediary potential transformer connected between the ground grid and true remote earth to measure ground potential rise. This intermediary device provides the relay with accurate GPR information, enabling the system to mentally transform ground-grid-referenced voltage measurements into true ground-referenced measurements through software compensation, thereby improving voltage reference accuracy while maintaining measurement simplicity
Solution Approach 2:
The patent transforms the voltage reference parameter from ground grid potential to true remote earth potential by measuring GPR and subtracting it from phase voltage measurements. This parameter change allows the system to use simple ground-grid-connected measurements while achieving accurate true ground referencing, thus improving voltage reference accuracy without complicating the measurement setup
Data Source
AI summary
Ground Potential Rise (GPR) systems and methods with depth sensing measure the GPR between the ground grid and the remote earth. Methods and systems described herein may provide a GPR measurement to an existing distance protection. A GPR system may comprise a set of potential transformers. The set of potential transformers may be coupled to different ground rods driven into the earth at different depths, respectively. One wire of the high voltage side of the potential transformer may be coupled to the ground grid of a substation, and the second wire of the potential transformer may be coupled to an insulated wire that is coupled to a ground rod or multiple of ground rods bonded together. The low voltage side of the potential transformer is used to connect Distance Relays, Voltage Relays, DFR or Alarms.