UHV Grid Metering Solution: 1000kV VT System Based on Ultra-High Insulation Stability

UHV Grid Metering Solution: 1000kV VT System Based on Ultra-High Insulation Stability​

In Ultra-High Voltage (UHV) grids, the high voltage level (e.g., 1000kV) imposes extremely stringent requirements on the insulation performance and measurement accuracy of metering devices. Conventional voltage transformers (VTs) are prone to insulation breakdown, excessive partial discharge, and thermal drift effects under ultra-high voltages, leading to metering failure or even equipment damage. This solution addresses the core challenge of "ultra-high voltage insulation stability," introducing an innovative Voltage Transformer (VT) solution specifically designed for 1000kV systems to ensure accurate and reliable acquisition of critical parameters.

​1. Technical Focus: Solving Ultra-High Voltage Insulation Stability​

Stable insulation at 1000kV is foundational for metering accuracy. This solution employs multiple synergistic technologies to construct an ultimate insulation barrier:

• ​Gas-Solid Composite Insulation:​​ Utilizes high-insulation-strength ​SF6 gas​ to fill a sealed chamber, isolating it from environmental influences; an outer layer of ​silicon rubber composite insulator housing​ provides dual protection against harsh weather and contamination.
• ​Intelligent Temperature Monitoring:​​ Features embedded ​Pt100 temperature sensors​ within the chamber to continuously monitor SF6 gas conditions, preventing insulation degradation or liquefaction risks caused by temperature rises.
• ​Step-Graded Voltage Equalization Structure:​​ Innovative ​4-stage series capacitive voltage division technology​ uniformly distributes ultra-high voltage layer-by-layer, eliminating local electric field distortion and significantly enhancing voltage distribution uniformity and insulation reliability.

​2. Core Configuration: Foundation for Precise Metering​

• ​Core Equipment:​​ 1000kV SF6 Gas-Insulated Voltage Transformer
• ​Voltage Division Structure:​​ 4-stage series capacitive voltage divider (efficient voltage equalization, reducing single-stage insulation stress)
• ​Insulation System:​​ Internally filled with high-purity SF6 gas + External silicon rubber composite insulator housing (Dual Protection)
• ​Condition Monitoring:​​ Embedded Pt100 temperature sensors (real-time sensing of internal environment)

​3. Core Advantages: Performance Significantly Exceeding Industry Standards​

• ​Ultra-High Accuracy:​​ Achieves an accuracy class of ​0.1, maintaining stability across ​80%-120%​​ of the rated voltage (Un), far exceeding conventional devices (typically class 0.2 or 0.5). Provides credible data for energy settlement, dispatch, and control.
• ​Exceptionally Low Loss:​​ Dielectric loss value ​​<0.05%​​ (at rated voltage), significantly reducing the device's self-consumption and operational heating, thereby extending lifespan.
• ​Superior Insulation:​​ Partial discharge level ​​≤3pC​ (Test condition: 1.2Um/√3), well below national standard requirements (typically 5-10pC), eliminating risks of insulation aging and breakdown caused by partial discharges.
• ​Wide-Range Stability:​​ Excellent divider structure design ensures linearity and accuracy within the ​80%-120% Un​ range, adapting to grid load fluctuations.

​4. Proactive Fault Safety Mechanism: 0.5-Second Emergency Cut-off​

• ​Dual Redundant Pressure Relief:​​ Features ​dual explosion-proof valves. If internal pressure abnormally surges (e.g., due to severe fault or overheating causing SF6 gasification), the valves trigger ​interlinked pressure release channels​ to prevent enclosure rupture.
• ​Millisecond-Level Protection Interlocking:​​ Pressure surge signals trigger the ​relay protection device, reliably isolating the faulted line ​within 0.5 seconds, minimizing the fault scope and ensuring the safety and stable operation of the main grid.