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.
