Smart Substation Voltage Transformer (VT) Digital Interface Solution

07/07/2025

Smart Substation Digital Interface Scheme
Technical Focus:​ Deep integration of the IEC 61850 protocol
This solution deeply integrates the IEC 61850 standard to build a future-oriented digital transformer system, achieving device interoperability, efficient data sharing, and intelligent system operation and maintenance.

Key Innovations

  1. Composite Sensing Technology
    • Rogowski Coil + Capacitive Voltage Divider Composite Sensing:​ Combines the Rogowski coil's wide frequency response (suitable for transient harmonics) with the high accuracy of capacitive voltage division, achieving non-saturated measurement of full-frequency signals (0.5Hz ~ 3kHz), eliminating ferroresonance risks inherent in traditional iron-core transformers.
  2. Embedded High-Precision Merging Unit (MU)
    • Supports IEC 61850-9-2LE Sampled Value (SV) transmission protocol.
    • Sampling rate: 4000Hz, meeting transient process analysis requirements.
    • GOOSE tripping delay <3ms, ensuring fast response of protection systems.
    • Real-time clock synchronization accuracy ±1μs (based on IRIG-B/PTP), guaranteeing timestamp consistency for system-wide data.
  3. Intelligent Self-Diagnosis System
    • Ferroresonance Online Early Warning:​ Monitors characteristic resonance frequencies (30-300Hz) in real-time and actively triggers damping strategies.
    • Winding Temperature Rise Warning:​ Embeds temperature sensors to dynamically analyze temperature rise curves and predict insulation aging risks.
    • Fault Location:​ Achieves bay-level precision, supporting remote operation and maintenance decisions.
  4. Industrial-Grade Electromagnetic Compatibility (EMC)
    • EMC Immunity Level: Class IV (Complies with GB/T 17626):
      • Radio Frequency Electromagnetic Field Immunity: 10V/m (80MHz~1GHz)
      • Surge/EFT Immunity: ±6kV/±4kV, suitable for complex electromagnetic environments.

Protocol Support & Core Specifications

Category

Parameter

Performance Indicator

Communication Protocol

IEC 61850-9-2LE

Supported

Sampled Value (SV)

Sampling Rate

4000Hz

GOOSE Performance

Trip Command Delay

<3ms

Time Synchronization

Real-time Clock Accuracy

±1μs (IRIG-B/PTP)

Measurement Accuracy

Phase Angle Error

​​<±0.2°

EMC Level

RF Immunity

Class IV (10V/m, 80MHz-1GHz)

Technical Value

  1. Fully Digital Architecture:
    Replaces analog signal cables with direct digital outputs (SV) from the MU, reducing system costs and operation & maintenance complexity.
  2. Enhanced Safety & Reliability:
    Self-diagnosis functions detect 90% of potential faults in advance. Class IV EMC immunity withstands strong electromagnetic interference within substations.
  3. System Compatibility:
    Deeply integrates the IEC 61850 protocol stack for seamless connection to various smart substation monitoring/protection systems (e.g., Siemens, ABB, NARI Group).
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