ABB Relion ® REU615 Voltage Protection and Control Device

ABB Relion ®  REU615 Voltage Protection and Control Device

Product positioning and application

RET670 is a multifunctional protection, monitoring, and control device designed specifically for power transformers, autotransformers, generator transformer groups, and parallel reactors. It supports dual winding and triple winding configurations and is suitable for single circuit breaker and multi circuit breaker scenarios. Its core advantages include:

High speed differential protection: automatic CT ratio matching and vector group compensation, supporting up to 6 constrained CT inputs, suitable for complex power grid structures.

Broadband adaptability: able to operate stably even in the event of frequency fluctuations in the power system (such as generator start stop).

Modular design: supports multiple hardware configurations and software feature packages, adapting to new installations and old system renovations.

Core protection function

Differential protection

Dual winding/triple winding differential (T2WPDIF/T3WPDIF): equipped with second and fifth harmonic braking to prevent excitation inrush current and overexcitation misoperation, with high sensitivity to internal turn to turn faults.

Low impedance grounding fault protection (REFPDIF): For winding grounding faults, it includes zero sequence current direction criteria and supports different CT transformation ratios.

High impedance differential (HZPDIF): suitable for special scenarios such as autotransformers and tertiary reactors.

Backup protection

Impedance protection: quadrilateral and M-O characteristics, supporting phase to phase/ground faults, including load intrusion algorithm, suitable for high impedance faults.

Overcurrent protection: Four stage phase overcurrent and ground overcurrent, configurable for direction or voltage control, supporting inverse time/definite time characteristics.

Voltage/frequency protection: overvoltage/undervoltage, overclocking/underfrequency protection, supporting voltage differentiation and frequency change rate detection.

Auxiliary protection

Thermal Overload Protection (TRPTTR): Dual time constant model, monitoring transformer winding temperature, supporting alarm and trip.

Circuit Breaker Failure Protection (CCRBRF): detects the rapid tripping of adjacent circuit breakers when they refuse to move.

Oil pillow/pressure release protection: Connect gas relay and pressure release signal to achieve rapid response to faults.

Monitoring and control functions

measurement and metrology

Real time monitoring of voltage, current, power, frequency and other parameters, supporting harmonic analysis and power quality monitoring.

Disturbance Recorder (DRPRDRE): records waveforms before and after faults, supports exporting in COMTRADE format.

Control and regulation

Load tap changer control (TR1ATCC/TR8ATCC): Automatic voltage regulation, supports parallel operation of single or multiple transformers, and adapts to different voltage regulation strategies.

SESRSYN synchronization check: detects the synchronization status of voltage on both sides and supports grid connection operation.

Condition monitoring

Trip circuit supervision, CT/PT disconnection detection, tap changer position monitoring, supporting equipment health status assessment.

Communication and Interface

communication protocol

Supports IEC 61850-8-1 GOOSE/SMV, IEC 60870-5-103, Modbus, DNP3, and is compatible with substation automation systems.

Redundant communication supports IEC 62439-3 to enhance system reliability.

hardware interface

Input module: current/voltage input (1A/5A, 110V/220V), RTD/mA input (such as tap changer position).

Output module: 24 relay outputs, supporting tripping and signal alarm, some models include high-speed static output.

Hardware and Installation

Hardware Architecture

There are three chassis sizes: 1/2 x 19 inches, 3/4 x 19 inches, and 1 x 19 inches, which support DIN rail or panel installation.

Modular design: power module (PSM), binary input/output module (BIM/BOM), communication module (OEM/SLM), etc.

Environmental adaptability

Working temperature: -10 ℃~+55 ℃, storage temperature: -40 ℃~+70 ℃, protection level IP40 (front board).

Compliant with industry standards such as EMC, vibration, and shock, suitable for harsh substation environments.

Working principle

Principle of Protection Function

Differential protection: Dual winding/triple winding differential protection (T2WPDIF/T3WPDIF) monitors and compares the current on each side in real-time through automatic CT ratio matching and vector group compensation. When an internal fault is detected and the differential current exceeds the set value, the protection device quickly activates. At the same time, utilizing the braking characteristics of second and fifth harmonics effectively prevents misoperation caused by excitation inrush current and overexcitation. Low impedance ground fault protection (REFPDIF) is designed for winding ground faults. By measuring the current of each winding and combining it with the zero sequence current direction criterion, it achieves high-sensitivity ground fault detection. High impedance differential protection (HZPDIF) utilizes external CT current summation, series resistance, and voltage dependent resistance, suitable for specific protection scenarios such as tee feeders or bus protection.

Backup protection: Impedance protection determines the location and type of the fault by measuring the impedance of the faulty circuit. Distance protection based on quadrilateral and M-O characteristics, for phase to phase and ground faults, achieves backup protection function according to the set impedance range and action time. Among them, the load intrusion algorithm can effectively deal with high resistance faults in overloaded lines. Overcurrent protection includes instantaneous phase overcurrent (PHPIOC) and four segment phase overcurrent (OC4PTOC), which can be configured with direction or voltage control. By monitoring the current magnitude and duration, combined with inverse time or definite time characteristics, timely action is taken in case of overcurrent faults. Voltage/frequency protection real-time monitoring system monitors voltage and frequency. When abnormal situations such as overvoltage, undervoltage, overclocking, and underflocking occur, protection operations are carried out according to the set action values and time.

Auxiliary protection: Thermal overload protection (TRPTTR) is based on a dual time constant model, which estimates the heat accumulation inside the transformer, i.e. temperature changes, by monitoring the current. When the temperature reaches the alarm value, a warning is issued. If it continues to rise to the trip value, the trip protection is activated to prevent the transformer from being damaged due to overheating. Circuit breaker failure protection (CCRBRF) detects the current and auxiliary contact status of the circuit breaker, and quickly trips adjacent circuit breakers when the circuit breaker refuses to move, ensuring that the fault can be cleared in a timely manner.

Monitoring function principle: The device monitors the operating parameters of the transformer in real time, such as voltage, current, power, frequency, etc., and converts analog quantities into digital quantities for processing and analysis through an internal measurement module. The disturbance recorder (DRPRDRE) can record the waveform of electrical changes before and after faults, store the data inside the device according to the set sampling rate and recording time, and support exporting in COMTRADE format for subsequent fault analysis. By real-time monitoring and analysis of these parameters, abnormal operating conditions of transformers can be detected in a timely manner, providing a basis for maintenance and repair.

Control function principle: On load tap changer control (TR1ATCC/TR8ATCC) automatically adjusts the tap changer position of the transformer according to changes in system voltage to maintain stable secondary voltage. When a single or multiple transformers are running in parallel, different voltage regulation strategies can be used to ensure that the system voltage is within a reasonable range. SESRSYN monitors and compares the phase, frequency, and amplitude of the voltages on both sides in real-time during grid connection operations. When the synchronization conditions are met, it sends out a signal to allow closing, ensuring the safety and stability of grid connection.