Patents for Relay Protection

Recent patents in relay protection cover transformer differential relays, digital protective relays, and advanced fault detection systems.

Transformer Protection Relay Patents

One notable patent, WO2019150619A1, describes a transformer protection relay device that calculates differential currents between primary and secondary windings to detect faults. The device determines the operating phase of a current differential relay and identifies the faulted phase based on phase current maxima and winding connection information, improving accuracy in transformer fault detection . This approach enhances the reliability of transformer protection by precisely identifying the accident phase.

Digital and Microprocessor-Based Relays

Digital protective relays, also called microprocessor-based relays, integrate multiple protection functions, metering, communication, and self-test capabilities. These systems sample voltage and current values from power lines, process the data using software algorithms, and can synchronize sampling across multiple relays using GPS signals. Such relays are capable of bus total overcurrent protection and system-wide fault detection . They represent a shift from traditional electromechanical relays to software-driven, highly configurable protection devices.

Advanced Relay Structures

The U.S. Patent 12,626,875 focuses on a relay with a movable magnetizer and anti-short circuit structure to improve high-voltage DC relay performance. The design addresses contact bounce and short-circuit handling while maintaining compactness and reliability. The movable magnetizer adjusts according to current flow, enhancing the relay's ability to withstand short-circuit conditions without compromising breaking ability .

Distributed and Intelligent Protection Systems

European Patent EP3018782B1 describes a distributed protection relay device that separates merging units and intelligent electronic devices (IEDs) for monitoring, control, and protection. The system collects analog and digital measurements from transformers and other equipment, transmits them via a process bus, and executes protective control commands. This architecture supports substation automation, real-time monitoring, and fault isolation .

Specialized Fault Detection Techniques

Patents also cover inrush current detection using Rogowski coils and methods for detecting loss of current transformer connections. These innovations allow relays to distinguish between normal transformer inrush currents and actual faults, preventing unnecessary tripping and improving system stability .

Summary

Patents in relay protection focus on:

• Transformer differential relays for accurate fault phase detection.
• Digital/microprocessor relays with integrated protection, metering, and communication.
• Relay structural innovations for high-voltage and DC applications.
• Distributed and intelligent protection systems for substation automation.
• Advanced fault detection methods, including inrush current and CT connection monitoring. These patents collectively enhance the accuracy, reliability, and automation of modern power system protection.