Voltage Transformer Solution: Transient Response Monitoring for Renewable Energy Stations

Ⅰ. Background and Pain Points​
Renewable energy stations (photovoltaic/wind power) face complex transient processes due to the large-scale application of power electronic devices, including: inverter shutdown surges, broadband resonance, and DC component interference. Conventional PTs/CTs are limited by bandwidth, response speed, and anti-saturation capability, making them unable to accurately capture transient voltage waveforms. This leads to protection misoperations, difficulty in fault location, and reduced equipment lifespan.

​Ⅱ. Transient Response Monitoring Solution for Renewable Energy Stations​
This solution is specifically designed for transient processes in renewable energy stations, with its core capability being wide-bandwidth, high-precision voltage measurement from DC to 5kHz.

• ​Technical Focus: Wide-Band Measurement Capability (DC-5kHz)​​
  Breaks through the bandwidth limitations of conventional transformers, covering key transient signals such as sub-synchronous oscillation (SSO), switching-frequency harmonics, high-frequency resonance, and slow DC offsets.
• ​Key Technologies​
  Resistive-Capacitive Divider + Rogowski Coil Integration:​​
   • Resistive-Capacitive Divider: Provides precise wide-band voltage measurement (10Hz-5kHz) with fast transient response and strong anti-interference.
   • Rogowski Coil: Measures the high-frequency current rate-of-change (di/dt). Integrated complementary signals construct a complete wide-band voltage signal, extending the effective bandwidth to 5kHz and overcoming single-sensor limitations.
   ​0.5Hz Low-Frequency Phase Compensation Circuit:​​
  For system ultra-low-frequency sub-synchronous oscillations (e.g., <1Hz), employs dedicated compensation algorithms and low-noise analog circuits to maintain phase error <0.1° at 0.5Hz, ensuring phase authenticity and amplitude accuracy of sub-synchronous components.
  Anti-DC Component Saturation Design (120% DC Offset):​​
  Employs high-Bsat nanocrystalline magnetic cores combined with active bias compensation technology. Withstands sustained DC offsets up to 120% of rated voltage without saturation, preventing measurement distortion caused by DC components from inverter faults or grid asymmetry.
• ​Dynamic Performance Specifications​
  Step Response Time: <20μs – Ensures rapid capture of instantaneous overvoltages caused by switching actions (e.g., IGBT turn-off).
  Harmonic Measurement Accuracy: Up to 51st order (2500Hz@50Hz) – THD accuracy ±0.5% – Meets requirements for precise power quality assessment and resonance analysis.
  Transient Overvoltage Recording Resolution: 10μs/point (equivalent to 100ksps sampling) – Provides high-resolution waveform recording for millisecond-level transient events (e.g., lightning strikes, ground faults).
• ​Application Scenarios​
  PV Inverter Turn-off Overvoltage Monitoring: Precisely measures voltage spikes during IGBT turn-off (dv/dt >10kV/μs), locates the source of reflected wave overvoltages, and optimizes RC snubber parameters and cable layout.
  Wind Farm Collection Line Resonance Analysis: Captures broadband resonance (e.g., 2-5kHz) caused by interactions between long cable distributed capacitance and SVGs/generator sets. Provides characteristic harmonic spectra and attenuation characteristics to guide active damping parameter tuning.
  Sub-Synchronous Oscillation (SSO/SSR) Monitoring: Accurately records phase and amplitude changes of sub-synchronous oscillation voltages within the 0.5-10Hz range, providing core data for oscillation source localization and suppression strategies.
  Protection Misoperation Analysis Due to DC Components: Provides accurate fundamental component measurements even under significant DC offset conditions, preventing protection device misjudgments caused by transformer saturation.