Surge Arrester Current Analysis for Overvoltage Protection
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Solution Overview
Problem
The installation of traditional PT-based zero sequence overvoltage protection systems for temporary overvoltage (TOV) and ground fault overvoltage (GFOV) protection in electric power systems is costly and time-consuming, posing barriers to the integration of renewable energy sources and Distributed Energy Resources (DERs, especially as the demand for DERs increases and reaches threshold ratios requiring such protection.
Innovation Solution
A method and system utilizing current sensors and microprocessor-based fault detection devices to measure and analyze surge arrester currents, employing real-time FFT algorithms and zero-sequence current algorithms to determine if overvoltage protection is needed, thereby initiating protective measures such as breaking circuit breakers to prevent damage from TOV and GFOV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional PT-based zero sequence overvoltage protection systems are installed, then TOV and GFOV protection capability is improved, but installation cost and time increase
Solution Approach 1:
The invention extracts the protection function from the traditional PT-based system and implements it through surge arrester current measurement and analysis. By monitoring the current through existing surge arresters and analyzing its frequency components, the system detects TOV and GFOV conditions without requiring separate PT installations, thereby reducing complexity while maintaining protection capability
Solution Approach 2:
The surge arrester current measurement system serves multiple functions: it monitors surge arrester health, detects TOV conditions, identifies GFOV events, and triggers protection actions. This multi-functional approach eliminates the need for dedicated PT-based protection hardware, reducing both installation cost and time while providing comprehensive overvoltage protection
2Measurement precision
If PT-based 3V0 protection is used, then overvoltage detection accuracy is improved, but ease of installation deteriorates
Solution Approach 1:
The surge arrester itself serves as the measurement sensor by providing current information that indicates overvoltage conditions. The existing surge arrester structure and its current characteristics are utilized directly for detection purposes, eliminating the need for separate PT installation and reducing installation complexity while maintaining detection accuracy
Solution Approach 2:
The invention replaces the mechanical/physical PT-based measurement system with an electrical signal analysis approach. By measuring and analyzing the electrical current through the surge arrester using FFT algorithms, the system achieves overvoltage detection without the physical infrastructure requirements of traditional PT installations
Data Source
AI summary
A detection scheme for temporary overvoltages and/or ground fault overvoltages in electric power systems is described. Current passing through a surge arrestor component of the power system is monitored. An algorithm for identifying one or more frequency components of the measured current signal is performed to screen out unwanted harmonics. In some embodiments, this is a frequency domain analysis. The frequency component(s) of the current signal is then compared to a calculated pickup current or pickup voltage of the system to determine if system protection steps should be undertaken.