Wind Farm Line Reclosing Using Parallel Reactor Zero-Crossing Detection
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Solution Overview
Problem
Existing adaptive reclosing methods for wind farm transmission lines fail to reliably identify fault nature, leading to potential secondary impacts on the power system due to permanent faults and requiring costly equipment modifications.
Innovation Solution
A three-phase adaptive reclosing method using parallel reactor current to detect differential mode current zero crossings, identifying fault nature through sliding time windows and zero crossing detection without signal injection equipment, allowing for timely and accurate reclosing decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed delay reclosing is used after circuit breaker trips, then reclosing operation is simple to implement, but power electronic equipment may be severely impacted if fault still exists
Solution Approach 1:
The patent performs preliminary fault nature identification by analyzing parallel reactor current characteristics before executing reclosing operation. The system detects whether differential mode current crosses zero axis during decay process, determining fault nature (permanent or transient) in advance, then decides reclosing strategy accordingly, avoiding premature reclosing that could damage equipment
Solution Approach 2:
The patent uses feedback from parallel reactor current signals to adjust reclosing decisions. By continuously monitoring the decay characteristics and zero-crossing behavior of differential mode current, the system receives feedback about fault status and dynamically determines whether to proceed with reclosing, ensuring equipment safety while maintaining operational simplicity
2Measurement precision
If active detection with signal injection is used to identify fault nature, then fault identification accuracy is improved, but equipment structure modification and cost increase
Solution Approach 1:
The patent employs the existing parallel reactor in the wind farm transmission line to perform self-diagnosis of fault nature. The parallel reactor's own current responses during fault conditions are analyzed to identify whether the fault is permanent or transient, eliminating the need for external signal injection equipment and keeping the system structure simple while achieving accurate fault identification
Solution Approach 2:
The patent uses the parallel reactor current as an intermediary to indirectly detect fault nature. Instead of directly injecting test signals into the transmission line, the system observes the natural current behavior of the parallel reactor during fault decay, using this intermediate measurement to infer fault characteristics without modifying the transmission line or adding injection equipment
3Measurement precision
If high sampling rate is used for fault detection, then measurement precision is improved, but computational complexity and processing burden increase
Solution Approach 1:
The patent extracts only the critical feature of zero-crossing detection from the complete current waveform analysis. By focusing specifically on whether the differential mode current crosses the zero axis during decay, the system achieves accurate fault identification without processing the entire high-frequency signal spectrum, significantly reducing computational burden while maintaining detection precision
Solution Approach 2:
The patent applies partial action by performing zero-crossing detection at strategically selected time points during the current decay process rather than continuous high-rate sampling. This approach uses minimal sampling points to capture the essential decay characteristics, achieving sufficient measurement precision with reduced computational complexity compared to continuous high-rate analysis
Data Source
AI summary
A three-phase adaptive reclosing method and system for wind farm transmission lines based on parallel reactor current is provided. When a phase to phase or three-phase fault occurs in the transmission line, the circuit breakers at both ends trip. The current transformer is used to sample the three-phase current signal of the parallel reactor, calculate the differential mode current of the parallel reactor, and perform zero crossing detection to construct a fault nature identification criterion. The fault nature is determined within the maximum discrimination time limit combined with the sliding time window. For permanent faults, the reclosing device is locked; for transient faults, calculate the time when the fault disappears and determine the reclosing time, and open the reclosing device. The method and system identifies the nature of faults by detecting whether the differential current of parallel reactors crosses the zero axis, with low sampling rate requirements, and small errors.