Digital Transformation Pathway for AIS Current Transformers Towards the New Power System Edge Intelligence Solution Compatible with Traditional Subs
I. Project Background
With the New Power System's escalating demands for dynamic monitoring accuracy, equipment compatibility, and data intelligence, traditional Air Insulated Switchgear (AIS) Current Transformers (CTs) urgently require digital transformation to achieve the following breakthroughs:
Compatibility Conflict: Need to simultaneously support both traditional analog substations and digital substations.
Accuracy Bottleneck: Insufficient PMU (Phasor Measurement Unit) synchronization accuracy restricting dynamic process analysis.
Data Deluge: Transmission of raw sampled values occupies over 90% of channel bandwidth.
II. Core Technical Solution
1. Dual-Mode Output Interface Architecture
Output Mode |
Technical Parameters |
Application Scenario |
Traditional Analog |
5A/1A, Accuracy Class 0.2S |
Protection devices, mechanical meter access |
Digital Output |
IEC 61850-9-2 LE Sampled Values (SV), 4000 Hz |
Merging Unit (MU), PMU centralized analysis |
Innovation: Employs magnetically isolated dual-winding design, avoiding digital/analog signal interference, achieving full-scale error < ±0.1%.
2. Microsecond (μs) Level Time Synchronization System
3. Edge Computing Intelligent Terminal
* Hardware Configuration:
* Dual-core ARM Cortex-M7 processor @ 480MHz
* 128KB SRAM + 4MB Flash storage
* Local Analysis Functions:
* Harmonic Distortion Ratio (THD) calculation (±0.2% accuracy when THD ≤ 1.5%)
* Three-phase imbalance analysis (Response time < 20ms)
* Load waveform feature extraction (Compression ratio 7:1)
* Data Transmission Optimization: Only uploads feature data, reducing bandwidth usage by 70%.
III. Transformation Implementation Pathway
Three-Phase Implementation Plan for Digital Transformation
Phase |
Activity |
Timeline, Effort (Quarter-Person) |
Device Layer Refit |
Traditional CT Replacement |
2025 Q1, 6qp |
Optical Fiber Network Deployment |
2025 Q2, 4qp |
|
System Layer Upgrade |
MU Data Access |
2025 Q3, 3qp |
Edge Computing Configuration |
2025 Q4, 2qp |
|
Advanced Applications |
PMU Dynamic Monitoring |
2026 Q1, 4qp |
AI Load Forecasting |
2026 Q2, 6qp |
(qp = Quarter-Person effort unit)
IV. Technical and Economic Benefits
Indicator |
Before Refit |
After Refit |
Improvement |
Data Acquisition Dimensions |
6 parameters |
27+ features |
350% Increase |
PMU Synchronization Accuracy |
10 μs |
0.8 μs |
12.5x Improvement |
Data Transmission Volume |
12 Mbps/unit |
3.6 Mbps/unit |
70% Reduction |
Fault Diagnosis Response Time |
300 ms |
45 ms |
85% Improvement |
Investment Payback Calculation:
Single Bay Refit Cost: ¥48,000
Annual Maintenance Cost Savings: ¥18,000
Avoided Capacity Expansion Savings: ¥50,000 (3-year period)
Static Payback Period: 2.7 years < Target 3 years
V. Typical Application Scenarios
Renewable Energy Plant Grid Connection Point
Captures second-level fluctuations in wind/solar power output.
Automatically triggers SVG (Static VAR Generator) upon harmonic violation.
Urban Load Center Substation
Dynamic capacity expansion based on edge computing.
Identifies impulsive loads within 0.1 seconds.
Traditional Substation Intelligent Refit
Preserves existing protection circuits.
Adds new optical fiber digital channels.
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